Clinical, Biomechanical, and Physiological Translational Interpretations of Human Resting Myofascial Tone or Tension

PubMed Central

Masi, Alfonse T.; Nair, Kalyani; Evans, Tyler; Ghandour, Yousef

2010-01-01

Background Myofascial tissues generate integrated webs and networks of passive and active tensional forces that provide stabilizing support and that control movement in the body. Passive [central nervous system (CNS)–independent] resting myofascial tension is present in the body and provides a low-level stabilizing component to help maintain balanced postures. This property was recently called “human resting myofascial tone” (HRMT). The HRMT model evolved from electromyography (EMG) research in the 1950s that showed lumbar muscles usually to be EMG-silent in relaxed gravity-neutral upright postures. Methods Biomechanical, clinical, and physiological studies were reviewed to interpret the passive stiffness properties of HRMT that help to stabilize various relaxed functions such as quiet balanced standing. Biomechanical analyses and experimental studies of the lumbar multifidus were reviewed to interpret its passive stiffness properties. The lumbar multifidus was illustrated as the major core stabilizing muscle of the spine, serving an important passive biomechanical role in the body. Results Research into muscle physiology suggests that passive resting tension (CNS-independent) is generated in sarcomeres by the molecular elasticity of low-level cycling cross-bridges between the actomyosin filaments. In turn, tension is complexly transmitted to intimately enveloping fascial matrix fibrils and other molecular elements in connective tissue, which, collectively, constitute the myofascial unit. Postural myofascial tonus varies with age and sex. Also, individuals in the population are proposed to vary in a polymorphism of postural HRMT. A few people are expected to have outlier degrees of innate postural hypotonicity or hypertonicity. Such biomechanical variations likely predispose to greater risk of related musculoskeletal disorders, a situation that deserves greater attention in clinical practice and research. Axial myofascial hypertonicity was hypothesized to predispose to ankylosing spondylitis. This often-progressive deforming condition of vertebrae and sacroiliac joints is characterized by stiffness features and particular localization of bony lesions at entheseal sites. Such unique features imply concentrations and transmissions of excessive force, leading to tissue micro-injury and maladaptive repair reactions. Conclusions The HRMT model is now expanded and translated for clinical relevance to therapists. Its passive role in helping to maintain balanced postures is supported by biomechanical principles of myofascial elasticity, tension, stress, stiffness, and tensegrity. Further research is needed to determine the molecular basis of HRMT in sarcomeres, the transmission of tension by the enveloping fascial elements, and the means by which the myofascia helps to maintain efficient passive postural balance in the body. Significant deficiencies or excesses of postural HRMT may predispose to symptomatic or pathologic musculoskeletal disorders whose mechanisms are currently unexplained. PMID:21589685

Destabilization of Human Balance Control by Static and Dynamic Head Tilts

NASA Technical Reports Server (NTRS)

Paloski, William H.; Wood, Scott J.; Feiveson, Alan H.; Black, F. Owen; Hwang, Emma Y.; Reschke, Millard F.

2004-01-01

To better understand the effects of varying head movement frequencies on human balance control, 12 healthy adult humans were studied during static and dynamic (0.14,0.33,0.6 Hz) head tilts of +/-30deg in the pitch and roll planes. Postural sway was measured during upright stance with eyes closed and altered somatosensory inputs provided by a computerized dynamic posturography (CDP) system. Subjects were able to maintain upright stance with static head tilts, although postural sway was increased during neck extension. Postural stability was decreased during dynamic head tilts, and the degree of destabilization varied directly with increasing frequency of head tilt. In the absence of vision and accurate foot support surface inputs, postural stability may be compromised during dynamic head tilts due to a decreased ability of the vestibular system to discern the orientation of gravity.

Coordination exercise and postural stability in elderly people: Effect of Tai Chi Chuan.

PubMed

Wong, A M; Lin, Y C; Chou, S W; Tang, F T; Wong, P Y

2001-05-01

To evaluate the effects of coordination exercise on postural stability in older individuals by Chinese shadow boxing, Tai Chi Chuan (TCC). Cross-sectional study. Research project in a hospital-based biomechanical laboratory. The TCC group (n = 25) had been practicing TCC regularly for 2 to 35 years. The control group (n = 14) included healthy and active older subjects. Static postural stability test: progressively harder sequential tests with 6 combinations of vision (eyes open, eyes closed, sway-referenced) and support (fixed, sway-referenced); and dynamic balance test: 3 tests of weight shifting (left to right, forward-backward, multidirectional) at 3 speeds. Static and dynamic balance of Sensory Organization Testing (SOT) of the Smart Balance Master System. In static postural control, the results showed no differences between the TCC or control group in the more simple conditions, but in the more complicated SOT (eyes closed with sway surface, sway vision with sway surface), the TCC group had significantly better results than the control group. The TCC group also had significantly better results in the rhythmic forward-backward weight-shifting test. Duration of practice did not seem to affect the stability of elder people. The elderly people who regularly practiced TCC showed better postural stability in the more challenged conditions than those who do not (eg, the condition with simultaneous disturbance of vision and proprioception). TCC as a coordination exercise may reduce the risk of a fall through maintaining the ability of posture control.

Therapeutic effects of an anti-gravity locomotor training (AlterG) on postural balance and cerebellum structure in children with Cerebral Palsy.

PubMed

Rasooli, A H; Birgani, P M; Azizi, Sh; Shahrokhi, A; Mirbagheri, M M

2017-07-01

We evaluated the therapeutic effects of anti-gravity locomotor treadmill (AlterG) training on postural stability in children with Cerebral Palsy (CP) and spasticity, particularly in the lower extremity. AlterG can facilitate walking by reducing the weight of CP children by up to 80%; it can also help subjects maintain an appropriate posture during the locomotor AlterG training. Thus, we hypothesized that AlterG training, for a sufficient period of time, has a potential to produce cerebellum neuroplasticity, and consequently result in an effective permanent postural stability. AlterG training was given for 45 minutes, three times a week for two months. Postural balance was evaluated using posturography. The parameters of the Romberg based posturography were extracted to quantify the Center of Balance (CoP). The neuroplasticity of Cerebellum was evaluated using a Diffusion Tensor Imaging (DTI). The evaluations were done pre- and post-training. The Fractional Anisotropy (FA) feature was used for quantifying structural changes in the cerebellum. The results showed that AlterG training resulted in an increase in average FA value of the cerebellum white matter following the training. The results of the posturography evaluations showed a consistent improvement in postural stability. These results were consistent in all subjects. Our findings indicated that the improvement in the posture was accompanied with the enhancement of the cerebellum white matter structure. The clinical implication is that AlterG training can be considered a therapeutic tool for an effective and permanent improvement of postural stability in CP children.

State-dependent sensorimotor processing: gaze and posture stability during simulated flight in birds.

PubMed

McArthur, Kimberly L; Dickman, J David

2011-04-01

Vestibular responses play an important role in maintaining gaze and posture stability during rotational motion. Previous studies suggest that these responses are state dependent, their expression varying with the environmental and locomotor conditions of the animal. In this study, we simulated an ethologically relevant state in the laboratory to study state-dependent vestibular responses in birds. We used frontal airflow to simulate gliding flight and measured pigeons' eye, head, and tail responses to rotational motion in darkness, under both head-fixed and head-free conditions. We show that both eye and head response gains are significantly higher during flight, thus enhancing gaze and head-in-space stability. We also characterize state-specific tail responses to pitch and roll rotation that would help to maintain body-in-space orientation during flight. These results demonstrate that vestibular sensorimotor processing is not fixed but depends instead on the animal's behavioral state.

State-dependent sensorimotor processing: gaze and posture stability during simulated flight in birds

PubMed Central

McArthur, Kimberly L.

2011-01-01

Vestibular responses play an important role in maintaining gaze and posture stability during rotational motion. Previous studies suggest that these responses are state dependent, their expression varying with the environmental and locomotor conditions of the animal. In this study, we simulated an ethologically relevant state in the laboratory to study state-dependent vestibular responses in birds. We used frontal airflow to simulate gliding flight and measured pigeons′ eye, head, and tail responses to rotational motion in darkness, under both head-fixed and head-free conditions. We show that both eye and head response gains are significantly higher during flight, thus enhancing gaze and head-in-space stability. We also characterize state-specific tail responses to pitch and roll rotation that would help to maintain body-in-space orientation during flight. These results demonstrate that vestibular sensorimotor processing is not fixed but depends instead on the animal's behavioral state. PMID:21307332

Postural stability changes in the elderly with cataract simulation and refractive blur.

PubMed

Anand, Vijay; Buckley, John G; Scally, Andy; Elliott, David B

2003-11-01

To determine the influence of cataractous and refractive blur on postural stability and limb-load asymmetry (LLA) and to establish how postural stability changes with the spatial frequency and contrast of the visual stimulus. Thirteen elderly subjects (mean age, 70.76 +/- 4.14 [SD] years) with no history of falls and normal vision were recruited. Postural stability was determined as the root mean square [RMS] of the center of pressure (COP) signal in the anterior-posterior (A-P) and medial-lateral directions and LLA was determined as the ratio of the average body weight placed on the more-loaded limb to the less-loaded limb, recorded during a 30-second period. Data were collected under normal standing conditions and with somatosensory system input disrupted. Measurements were repeated with four visual targets with high (8 cyc/deg) or low (2 cyc/deg) spatial frequency and high (Weber contrast, approximately 95%) or low (Weber contrast, approximately 25%) contrast. Postural stability was measured under conditions of binocular refractive blur of 0, 1, 2, 4, and 8 D and with cataract simulation. The data were analyzed in a population-averaged linear model. The cataract simulation caused significant increases in postural instability equivalent to that caused by 8-D blur conditions, and its effect was greater when the input from the somatosensory system was disrupted. High spatial frequency targets increased postural instability. Refractive blur, cataract simulation, or eye closure had no effect on LLA. Findings indicate that cataractous and refractive blur increase postural instability, and show why the elderly, many of whom have poor vision along with musculoskeletal and central nervous system degeneration, are at greater risk of falling. Findings also highlight that changes in contrast sensitivity rather than resolution changes are responsible for increasing postural instability. Providing low spatial frequency information in certain environments may be useful in maintaining postural stability. Correcting visual impairment caused by uncorrected refractive error and cataracts could be a useful intervention strategy to help prevent falls and fall-related injuries in the elderly.

Influences of arm proprioception and degrees of freedom on postural control with light touch feedback.

PubMed

Rabin, Ely; DiZio, Paul; Ventura, Joel; Lackner, James R

2008-02-01

Lightly touching a stable surface with one fingertip strongly stabilizes standing posture. The three main features of this phenomenon are fingertip contact forces maintained at levels too low to provide mechanical support, attenuation of postural sway relative to conditions without fingertip touch, and center of pressure (CP) lags changes in fingertip shear forces by approximately 250 ms. In the experiments presented here, we tested whether accurate arm proprioception and also whether the precision fingertip contact afforded by the arm's many degrees of freedom are necessary for postural stabilization by finger contact. In our first experiment, we perturbed arm proprioception and control with biceps brachii vibration (120-Hz, 2-mm amplitude). This degraded postural control, resulting in greater postural sway amplitudes. In a second study, we immobilized the touching arm with a splint. This prevented precision fingertip contact but had no effect on postural sway amplitude. In both experiments, the correlation and latency of fingertip contact forces to postural sway were unaffected. We conclude that postural control is executed based on information about arm orientation as well as tactile feedback from light touch, although precision fingertip contact is not essential. The consistent correlation and timing of CP movement and fingertip forces across conditions in which postural sway amplitude and fingertip contact are differentially disrupted suggests posture and the fingertip are controlled in parallel with feedback from the fingertip in this task.

Adaptability of anticipatory postural adjustments associated with voluntary movement

PubMed Central

Yiou, Eric; Caderby, Teddy; Hussein, Tarek

2012-01-01

The control of balance is crucial for efficiently performing most of our daily motor tasks, such as those involving goal-directed arm movements or whole body displacement. The purpose of this article is twofold. Firstly, it is to recall how balance can be maintained despite the different sources of postural perturbation arising during voluntary movement. The importance of the so-called “anticipatory postural adjustments” (APA), taken as a “line of defence” against the destabilizing effect induced by a predicted perturbation, is emphasized. Secondly, it is to report the results of recent studies that questioned the adaptability of APA to various constraints imposed on the postural system. The postural constraints envisaged here are classified into biomechanical (postural stability, superimposition of motor tasks), (neuro) physiological (fatigue), temporal (time pressure) and psychological (fear of falling, emotion). Overall, the results of these studies point out the capacity of the central nervous system (CNS) to adapt the spatio-temporal features of APA to each of these constraints. However, it seems that, depending on the constraint, the “priority” of the CNS was focused on postural stability maintenance, on body protection and/or on maintenance of focal movement performance. PMID:22720267

Postural orientation and equilibrium: what do we need to know about neural control of balance to prevent falls?

PubMed

Horak, Fay B

2006-09-01

Postural control is no longer considered simply a summation of static reflexes but, rather, a complex skill based on the interaction of dynamic sensorimotor processes. The two main functional goals of postural behaviour are postural orientation and postural equilibrium. Postural orientation involves the active alignment of the trunk and head with respect to gravity, support surfaces, the visual surround and internal references. Sensory information from somatosensory, vestibular and visual systems is integrated, and the relative weights placed on each of these inputs are dependent on the goals of the movement task and the environmental context. Postural equilibrium involves the coordination of movement strategies to stabilise the centre of body mass during both self-initiated and externally triggered disturbances of stability. The specific response strategy selected depends not only on the characteristics of the external postural displacement but also on the individual's expectations, goals and prior experience. Anticipatory postural adjustments, prior to voluntary limb movement, serve to maintain postural stability by compensating for destabilising forces associated with moving a limb. The amount of cognitive processing required for postural control depends both on the complexity of the postural task and on the capability of the subject's postural control system. The control of posture involves many different underlying physiological systems that can be affected by pathology or sub-clinical constraints. Damage to any of the underlying systems will result in different, context-specific instabilities. The effective rehabilitation of balance to improve mobility and to prevent falls requires a better understanding of the multiple mechanisms underlying postural control.

Dynamic stability control in forward falls: postural corrections after muscle fatigue in young and older adults.

PubMed

Mademli, Lida; Arampatzis, Adamantios; Karamanidis, Kiros

2008-06-01

Many studies report that muscle strength loss may alter the human system's capacity to generate rapid force for balance corrections after perturbations, leading to deficient recovery behaviours. Yet little is known regarding the effect of modifications in the neuromuscular system induced by fatigue on dynamic stability control during postural perturbations. This study investigates the effect of muscle strength decline induced by fatiguing contractions on the dynamic stability control of young and older adults during forward falls. Eleven young and eleven older male adults had to regain balance after sudden falls before and after submaximal fatiguing knee extension-flexion contractions. Young subjects had a higher margin of stability than older ones before and after the fatiguing task. This reflects their enhanced ability in using mechanisms for maintaining dynamic stability (i.e. a greater base of support). The margin of stability, the boundary of the base of support and the position of the extrapolated centre of mass, remained unaffected by the reduction in muscle strength induced by the fatiguing contractions, indicating an appropriate adjustment of the motor commands to compensate the deficit in muscle strength. Both young and older adults were able to counteract the decreased horizontal ground reaction forces after the fatiguing task by flexing their knee to a greater extent, leading to similar decreases in the horizontal velocity of centre of mass as in the pre fatigue condition. The results demonstrate the ability of the central nervous system to rapidly modify the execution of postural corrections including mechanisms for maintaining dynamic stability.

Obesity Impact on the Attentional Cost for Controlling Posture

PubMed Central

Mignardot, Jean-Baptiste; Olivier, Isabelle; Promayon, Emmanuel; Nougier, Vincent

2010-01-01

Background This study investigated the effects of obesity on attentional resources allocated to postural control in seating and unipedal standing. Methods Ten non obese adults (BMI = 22.4±1.3, age = 42.4±15.1) and 10 obese adult patients (BMI = 35.2±2.8, age = 46.2±19.6) maintained postural stability on a force platform in two postural tasks (seated and unipedal). The two postural tasks were performed (1) alone and (2) in a dual-task paradigm in combination with an auditory reaction time task (RT). Performing the RT task together with the postural one was supposed to require some attentional resources that allowed estimating the attentional cost of postural control. 4 trials were performed in each condition for a total of 16 trials. Findings (1) Whereas seated non obese and obese patients exhibited similar centre of foot pressure oscillations (CoP), in the unipedal stance only obese patients strongly increased their CoP sway in comparison to controls. (2) Whatever the postural task, the additional RT task did not affect postural stability. (3) Seated, RT did not differ between the two groups. (4) RT strongly increased between the two postural conditions in the obese patients only, suggesting that body schema and the use of internal models was altered with obesity. Interpretation Obese patients needed more attentional resources to control postural stability during unipedal stance than non obese participants. This was not the case in a more simple posture such as seating. To reduce the risk of fall as indicated by the critical values of CoP displacement, obese patients must dedicate a strong large part of their attentional resources to postural control, to the detriment of non-postural events. Obese patients were not able to easily perform multitasking as healthy adults do, reflecting weakened psycho-motor abilities. PMID:21187914

Improvement of anticipatory postural adjustments for balance control: effect of a single training session.

PubMed

Kanekar, Neeta; Aruin, Alexander S

2015-04-01

Humans use anticipatory and compensatory postural strategies to maintain and restore balance when perturbed. Inefficient generation and utilization of anticipatory postural adjustments (APAs) is one of the reasons for postural instability. The aim of the study was to investigate the role of training in improvement of APAs and its effect on subsequent control of posture. Thirteen healthy young adults were exposed to predictable external perturbations before and after a single training session consisting of catches of a medicine ball thrown at the shoulder level. 3-D body kinematics, EMG activity of thirteen trunk and lower limb muscles, and ground reaction forces were recorded before and immediately after a single training session. Muscle onsets, EMG integrals, center of pressure (COP), and center of mass (COM) displacements were analyzed during the anticipatory and compensatory phases of postural control. The effect of a single training session was seen as significantly early muscle onsets and larger anticipatory COP displacements. As a result, significantly smaller peak COM displacements were observed after the perturbation indicating greater postural stability. The outcome of this study provides a background for examining the role of training in improvement of APAs and its effect on postural stability in individuals in need. Copyright © 2014 Elsevier Ltd. All rights reserved.

Attentional Focus Effects as a Function of Task Difficulty

ERIC Educational Resources Information Center

Wulf, Gabriele; Tollner, Thomas; Shea, Charles H.

2007-01-01

The purpose of the present study was to examine whether the advantages of adopting an external focus would be seen primarily for relatively challenging (postural stability) tasks but not less demanding tasks. To examine this, the authors used balance tasks that imposed increased challenges to maintaining stability. The present results support the…

The effect of exhausting aerobic exercise on the timing of anticipatory postural adjustments.

PubMed

Strang, A J; Choi, H J; Berg, W P

2008-03-01

The aim of the study was to investigate the influence of exhausting aerobic exercise on the timing of anticipatory postural adjustments (APAs). The APAs of 12 participants were recorded at baseline, after a .VO2max running test, and again following a 45-min rest period. APAs were induced using a rapid bilateral arm-raising maneuver, and were analyzed in the rectus abdominis, hamstring group, gluteal group, and lumbar and thoracic paraspinal muscles using electromyography. Postural stability was assessed by monitoring anterior/posterior displacement of the center of pressure using a force plate. We hypothesized that APA onset would be ear lier following exhausting aerobic exercise as compared to the baseline measures, but that this effect would be transient (i.e., APA onset following the rest period would not differ from that at baseline). Exhausting aerobic exercise resulted in a significantly earlier APA in one of the 5 muscles evaluated, the thoracic paraspinal group, and this effect persisted 45-min postexercise. Exhausting aerobic exercise did not affect postural stability during the rapid arm-raising maneuver. The findings lend tentative support for the notion that earlier APAs constitute a functional adaptation by the motor system to maintain postural stability in the presence of fatigue.

Embodied prosthetic arm stabilizes body posture, while unembodied one perturbs it.

PubMed

Imaizumi, Shu; Asai, Tomohisa; Koyama, Shinichi

2016-10-01

Senses of ownership (this arm belongs to me) and agency (I am controlling this arm) originate from sensorimotor system. External objects can be integrated into the sensorimotor system following long-term use, and recognized as one's own body. We examined how an (un)embodied prosthetic arm modulates whole-body control, and assessed the components of prosthetic embodiment. Nine unilateral upper-limb amputees participated. Four frequently used their prosthetic arm, while the others rarely did. Their postural sway was measured during quiet standing with or without their prosthesis. The frequent users showed greater sway when they removed the prosthesis, while the rare users showed greater sway when they fitted the prosthesis. Frequent users reported greater everyday feelings of postural stabilization by prosthesis and a larger sense of agency over the prosthesis. We suggest that a prosthetic arm maintains or perturbs postural control, depending on the prosthetic embodiment, which involves sense of agency rather than ownership. Copyright © 2016 Elsevier Inc. All rights reserved.

A test of fixed and moving reference point control in posture.

PubMed

Lee, I-Chieh; Pacheco, Matheus M; Newell, Karl M

2017-01-01

This study investigated two contrasting assumptions of the regulation of posture: namely, fixed and moving reference point control. These assumptions were tested in terms of time-dependent structure and data distribution properties when stability is manipulated. Fifteen male participants performed a tightrope simulated balance task that is, maintaining a tandem stance while holding a pole. Pole length (and mass) and the standing support surface (fixed surface/balance board) were manipulated so as to mechanically change the balance stability. The mean and standard deviation (SD) of COP length were reduced with pole length increment but only in the balance board surface condition. Also, the SampEn was lower with greater pole length for the balance board but not the fixed surface. More than one peak was present in the distribution of COP in the majority of trials. Collectively, the findings provide evidence for a moving reference point in the maintenance of postural stability for quiet standing. Copyright © 2016 Elsevier B.V. All rights reserved.

Dominant side in single-leg stance stability during floor oscillations at various frequencies

PubMed Central

2014-01-01

Background We investigated lateral dominance in the postural stability of single-leg stance with anteroposterior floor oscillations at various frequencies. Methods Thirty adults maintained a single-leg stance on a force platform for 20 seconds per trial. Trials were performed with no oscillation (static condition) and with anteroposterior floor oscillations (2.5-cm amplitude) at six frequencies: 0.25, 0.5, 0.75, 1.0, 1.25 and 1.5 Hz (dynamic condition). A set of three trials was performed on each leg in each oscillation frequency in random order. The mean speed of the center of pressure in the anteroposterior direction (CoPap) was calculated as an index of postural stability, and frequency analysis of CoPap sway was performed. Footedness for carrying out mobilizing activities was assessed with a questionnaire. Results CoPap speed exponentially increased as oscillation frequency increased in both legs. The frequency analysis of CoPap showed a peak <0.3 Hz at no oscillation. The frequency components at 0.25-Hz oscillation included common components with no oscillation and those at 1.5-Hz oscillation showed the maximum amplitude among all conditions. Postural stability showed no significant difference between left- and right-leg stance at no oscillation and oscillations ≤1.25 Hz, but at 1.5-Hz oscillation was significantly higher in the right-leg stance than in the left-leg stance. For the lateral dominance of postural stability at individual levels, the lateral difference in postural stability at no oscillation was positively correlated with that at 0.25-Hz oscillation (r = 0.51) and negatively correlated with that at 1.5-Hz oscillation (r = -0.53). For 70% of subjects, the dominant side of postural stability was different at no oscillation and 1.5-Hz oscillation. In the subjects with left- or right-side dominance at no oscillation, 94% or 38% changed their dominant side at 1.5-Hz oscillation, with a significant difference between these percentages. In the 1.5-Hz oscillation, 73% of subjects had concordance between the dominant side of postural stability and that of mobilizing footedness. Conclusion In static conditions, there was no lateral dominance of stability during single-leg stance. At 1.5-Hz oscillation, the highest frequency, right-side dominance of postural stability was recognized. Functional role in supporting leg may be divided between left and right legs according to the change of balance condition from static to dynamic. PMID:25127541

Haptic stabilization of posture: changes in arm proprioception and cutaneous feedback for different arm orientations

NASA Technical Reports Server (NTRS)

Rabin, E.; Bortolami, S. B.; DiZio, P.; Lackner, J. R.

1999-01-01

Postural sway during quiet stance is attenuated by actively maintained contact of the index finger with a stationary surface, even if the level of applied force (<1 N) cannot provide mechanical stabilization. In this situation, changes in force level at the fingertip lead changes in center of foot pressure by approximately 250 ms. These and related findings indicate that stimulation of the fingertip combined with proprioceptive information about the hand and arm can serve as an active sensor of body position relative to the point of contact. A geometric analysis of the relationship between hand and torso displacement during body sway led to the prediction that arm and hand proprioceptive and finger somatosensory information about body sway would be maximized with finger contact in the plane of body sway. Therefore, the most postural stabilization should be possible with such contact. To test this analysis, subjects touched a laterally versus anteriorly placed surface while in each of two stances: the heel-to-toe tandem Romberg stance that reduces medial-lateral stability and the heel-to-heel, toes-outward, knees-bent, "duck stance" that reduces fore-aft stability. Postural sway was always least with finger contact in the unstable plane: for the tandem stance, lateral fingertip contact was significantly more effective than frontal contact, and, for the duck stance, frontal contact was more effective than lateral fingertip contact. Force changes at the fingertip led changes in center of pressure of the feet by approximately 250 ms for both fingertip contact locations for both test stances. These results support the geometric analysis, which showed that 1) arm joint angles change by the largest amount when fingertip contact is maintained in the plane of greatest sway, and 2) the somatosensory cues at the fingertip provide both direction and amplitude information about sway when the finger is contacting a surface in the unstable plane.

Haptic stabilization of posture: changes in arm proprioception and cutaneous feedback for different arm orientations.

PubMed

Rabin, E; Bortolami, S B; DiZio, P; Lackner, J R

1999-12-01

Postural sway during quiet stance is attenuated by actively maintained contact of the index finger with a stationary surface, even if the level of applied force (<1 N) cannot provide mechanical stabilization. In this situation, changes in force level at the fingertip lead changes in center of foot pressure by approximately 250 ms. These and related findings indicate that stimulation of the fingertip combined with proprioceptive information about the hand and arm can serve as an active sensor of body position relative to the point of contact. A geometric analysis of the relationship between hand and torso displacement during body sway led to the prediction that arm and hand proprioceptive and finger somatosensory information about body sway would be maximized with finger contact in the plane of body sway. Therefore, the most postural stabilization should be possible with such contact. To test this analysis, subjects touched a laterally versus anteriorly placed surface while in each of two stances: the heel-to-toe tandem Romberg stance that reduces medial-lateral stability and the heel-to-heel, toes-outward, knees-bent, "duck stance" that reduces fore-aft stability. Postural sway was always least with finger contact in the unstable plane: for the tandem stance, lateral fingertip contact was significantly more effective than frontal contact, and, for the duck stance, frontal contact was more effective than lateral fingertip contact. Force changes at the fingertip led changes in center of pressure of the feet by approximately 250 ms for both fingertip contact locations for both test stances. These results support the geometric analysis, which showed that 1) arm joint angles change by the largest amount when fingertip contact is maintained in the plane of greatest sway, and 2) the somatosensory cues at the fingertip provide both direction and amplitude information about sway when the finger is contacting a surface in the unstable plane.

Classification of posture maintenance data with fuzzy clustering algorithms

NASA Technical Reports Server (NTRS)

Bezdek, James C.

1992-01-01

Sensory inputs from the visual, vestibular, and proprioreceptive systems are integrated by the central nervous system to maintain postural equilibrium. Sustained exposure to microgravity causes neurosensory adaptation during spaceflight, which results in decreased postural stability until readaptation occurs upon return to the terrestrial environment. Data which simulate sensory inputs under various sensory organization test (SOT) conditions were collected in conjunction with Johnson Space Center postural control studies using a tilt-translation device (TTD). The University of West Florida applied the fuzzy c-meams (FCM) clustering algorithms to this data with a view towards identifying various states and stages of subjects experiencing such changes. Feature analysis, time step analysis, pooling data, response of the subjects, and the algorithms used are discussed.

Effect of stump flexion contracture with and without prosthetic alignment intervention towards postural stability among transtibial prosthesis users

NASA Astrophysics Data System (ADS)

Ghazali, M. F.; Razak, N. A. Abd; Abu Osman, N. A.; Gholizadeh, H.

2017-06-01

Knee flexion contracture on a stump side is a phenomenon in which the stump cannot move in normal range of motion (ROM) or cannot be fully extended. This study has been carried out by using Biodex Stability System (BSS) in order to investigate the effect of stump flexion contracture towards the postural stability among the transtibial prosthesis users with the intervention of alignment accommodation. The BSS provides the reading of anterior-posterior stability index (APSI), medial-lateral stability index (MLSI), and overall stability index (OSI). Higher reading of the index indicates lesser stability. Each of the subjects had been tested in three different sessions that were Visit 1 (before contracture improvement), Visit 2 (after contracture improvement without alignment readjustment), and Visit 3 (after contracture improvement with alignment readjustment). The APSI reading was significantly higher during Visit 2 compared to Visit 1 and Visit 3. The OSI during Visit 2 was also found significantly higher compared to Visit 3. In Visit 2, the degree of contracture was significantly improved with 44.1% less than Visit 1. The stability index in anterior-posterior aspect (APSI) was proven to be lower as the prosthetic alignment was adjusted according to the ROM of knee. This finding explained that the alignment set up based on the adaptation with the stump’s ROM can contribute positively in maintaining postural stability.

Static and dynamic posture control in postlingual cochlear implanted patients: effects of dual-tasking, visual and auditory inputs suppression

PubMed Central

Bernard-Demanze, Laurence; Léonard, Jacques; Dumitrescu, Michel; Meller, Renaud; Magnan, Jacques; Lacour, Michel

2014-01-01

Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body's position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI) surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of postlingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static (stable platform) and dynamic (platform in translation) conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO) and eyes closed (EC) conditions, with the CI activated (ON) or not (OFF). Results showed that the postural performance of the CI patients strongly differed from the controls, mainly in the EC condition. The CI patients showed significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk: they behaved dynamically without vision like an inverted pendulum while the controls showed a whole body rigidification strategy. Hearing (prosthesis on) as well as dual-tasking did not really improve the dynamic postural performance of the CI patients. We conclude that CI patients become strongly visual dependent mainly in challenging postural conditions, a result they have to be awarded of particularly when getting older. PMID:24474907

Static and dynamic posture control in postlingual cochlear implanted patients: effects of dual-tasking, visual and auditory inputs suppression.

PubMed

Bernard-Demanze, Laurence; Léonard, Jacques; Dumitrescu, Michel; Meller, Renaud; Magnan, Jacques; Lacour, Michel

2013-01-01

Posture control is based on central integration of multisensory inputs, and on internal representation of body orientation in space. This multisensory feedback regulates posture control and continuously updates the internal model of body's position which in turn forwards motor commands adapted to the environmental context and constraints. The peripheral localization of the vestibular system, close to the cochlea, makes vestibular damage possible following cochlear implant (CI) surgery. Impaired vestibular function in CI patients, if any, may have a strong impact on posture stability. The simple postural task of quiet standing is generally paired with cognitive activity in most day life conditions, leading therefore to competition for attentional resources in dual-tasking, and increased risk of fall particularly in patients with impaired vestibular function. This study was aimed at evaluating the effects of postlingual cochlear implantation on posture control in adult deaf patients. Possible impairment of vestibular function was assessed by comparing the postural performance of patients to that of age-matched healthy subjects during a simple postural task performed in static (stable platform) and dynamic (platform in translation) conditions, and during dual-tasking with a visual or auditory memory task. Postural tests were done in eyes open (EO) and eyes closed (EC) conditions, with the CI activated (ON) or not (OFF). Results showed that the postural performance of the CI patients strongly differed from the controls, mainly in the EC condition. The CI patients showed significantly reduced limits of stability and increased postural instability in static conditions. In dynamic conditions, they spent considerably more energy to maintain equilibrium, and their head was stabilized neither in space nor on trunk: they behaved dynamically without vision like an inverted pendulum while the controls showed a whole body rigidification strategy. Hearing (prosthesis on) as well as dual-tasking did not really improve the dynamic postural performance of the CI patients. We conclude that CI patients become strongly visual dependent mainly in challenging postural conditions, a result they have to be awarded of particularly when getting older.

Mechanisms of postural control in alcoholic men and women: biomechanical analysis of musculoskeletal coordination during quiet standing.

PubMed

Sullivan, Edith V; Rose, Jessica; Pfefferbaum, Adolf

2010-03-01

Excessive sway during quiet standing is a common sequela of chronic alcoholism even with prolonged sobriety. Whether alcoholic men and women who have remained abstinent from alcohol for weeks to months differ from each other in the degree of residual postural instability and biomechanical control mechanisms has not been directly tested. We used a force platform to characterize center-of-pressure biomechanical features of postural sway, with and without stabilizing conditions from touch, vision, and stance, in 34 alcoholic men, 15 alcoholic women, 22 control men, and 29 control women. Groups were matched in age (49.4 years), general intelligence, socioeconomic status, and handedness. Each alcoholic group was sober for an average of 75 days. Analysis of postural sway when using all 3 stabilizing conditions versus none revealed diagnosis and sex differences in ability to balance. Alcoholics had significantly longer sway paths, especially in the anterior-posterior direction, than controls when maintaining erect posture without balance aids. With stabilizing conditions the sway paths of all groups shortened significantly, especially those of alcoholic men, who demonstrated a 3.1-fold improvement in sway path difference between the easiest and most challenging conditions; the remaining 3 groups, each showed a approximately 2.4-fold improvement. Application of a mechanical model to partition sway paths into open-loop and closed-loop postural control systems revealed that the sway paths of the alcoholic men but not alcoholic women were characterized by greater short-term (open-loop) diffusion coefficients without aids, often associated with muscle stiffening response. With stabilizing factors, all 4 groups showed similar long-term (closed loop) postural control. Correlations between cognitive abilities and closed-loop sway indices were more robust in alcoholic men than alcoholic women. Reduction in sway and closed-loop activity during quiet standing with stabilizing factors shows some differential expression in men and women with histories of alcohol dependence. Nonetheless, enduring deficits in postural instability of both alcoholic men and alcoholic women suggest persisting liability for falling.

Contribution of supraspinal systems to generation of automatic postural responses

PubMed Central

Deliagina, Tatiana G.; Beloozerova, Irina N.; Orlovsky, Grigori N.; Zelenin, Pavel V.

2014-01-01

Different species maintain a particular body orientation in space due to activity of the closed-loop postural control system. In this review we discuss the role of neurons of descending pathways in operation of this system as revealed in animal models of differing complexity: lower vertebrate (lamprey) and higher vertebrates (rabbit and cat). In the lamprey and quadruped mammals, the role of spinal and supraspinal mechanisms in the control of posture is different. In the lamprey, the system contains one closed-loop mechanism consisting of supraspino-spinal networks. Reticulospinal (RS) neurons play a key role in generation of postural corrections. Due to vestibular input, any deviation from the stabilized body orientation leads to activation of a specific population of RS neurons. Each of the neurons activates a specific motor synergy. Collectively, these neurons evoke the motor output necessary for the postural correction. In contrast to lampreys, postural corrections in quadrupeds are primarily based not on the vestibular input but on the somatosensory input from limb mechanoreceptors. The system contains two closed-loop mechanisms – spinal and spino-supraspinal networks, which supplement each other. Spinal networks receive somatosensory input from the limb signaling postural perturbations, and generate spinal postural limb reflexes. These reflexes are relatively weak, but in intact animals they are enhanced due to both tonic supraspinal drive and phasic supraspinal commands. Recent studies of these supraspinal influences are considered in this review. A hypothesis suggesting common principles of operation of the postural systems stabilizing body orientation in a particular plane in the lamprey and quadrupeds, that is interaction of antagonistic postural reflexes, is discussed. PMID:25324741

The association between later cortical potentials and later phases of postural reactions evoked by perturbations to upright stance.

PubMed

Quant, Sylvia; Maki, Brian E; McIlroy, William E

2005-06-24

Previous studies have suggested that early cortical potentials (e.g. N1) that are evoked by perturbations to upright stance are associated with sensory processing of the initial perturbation and that later potentials may represent cognitive processing of this perturbation. However, it has also been suggested that later cortical potentials could reflect sensory and motor processing of later phases of the postural reaction. The current study set out to provide additional insight into the association between perturbation-evoked cortical potentials and postural reactions evoked by whole-body perturbations. By altering the deceleration onset of the perturbation, which altered the timing of later postural responses, we determined whether changes in later postural responses were associated with changes in later potentials. Based on previous work, we hypothesized that later potentials would not be associated with changes in later postural responses. During stance, seven healthy young adults were instructed to maintain their balance following two types of perturbations: (1) acceleration phase immediately followed by a deceleration phase (TASK 1), and (2) acceleration phase followed by a delayed deceleration phase (TASK 2). In spite of profound task differences in later postural responses, results revealed no significant differences in later potentials. This work provides additional support for the idea that latter elements of perturbation-evoked cortical responses are likely independent of evoked motor reactions required to maintain stability.

The addition of body armor diminishes dynamic postural stability in military soldiers.

PubMed

Sell, Timothy C; Pederson, Jonathan J; Abt, John P; Nagai, Takashi; Deluzio, Jennifer; Wirt, Michael D; McCord, Larry J; Lephart, Scott M

2013-01-01

Poor postural stability has been identified as a risk factor for lower extremity musculoskeletal injury. The additional weight of body armor carried by Soldiers alters static postural stability and may predispose Soldiers to lower extremity musculoskeletal injuries. However, static postural stability tasks poorly replicate the dynamic military environment, which places considerable stress on the postural control system during tactical training and combat. Therefore, the purpose of this study was to examine the effects of body armor on dynamic postural stability during single-leg jump landings. Thirty-six 101st Airborne Division (Air Assault) Soldiers performed single-leg jump landings in the anterior direction with and without wearing body armor. The dynamic postural stability index and the individual stability indices (medial-lateral stability index, anterior-posterior stability index, and vertical stability index) were calculated for each condition. Paired sample t-tests were performed to determine differences between conditions. Significant differences existed for the medial-lateral stability index, anterior-posterior stability index, vertical stability index, and dynamic postural stability index (p < 0.05). The addition of body armor resulted in diminished dynamic postural stability, which may result in increased lower extremity injuries. Training programs should address the altered dynamic postural stability while wearing body armor in attempts to promote adaptations that will result in safer performance during dynamic tasks.

Improving posture-motor dual-task with a supraposture-focus strategy in young and elderly adults

PubMed Central

Yu, Shu-Han

2017-01-01

In a postural-suprapostural task, appropriate prioritization is necessary to achieve task goals and maintain postural stability. A “posture-first” principle is typically favored by elderly people in order to secure stance stability, but this comes at the cost of reduced suprapostural performance. Using a postural-suprapostural task with a motor suprapostural goal, this study investigated differences between young and older adults in dual-task cost across varying task prioritization paradigms. Eighteen healthy young (mean age: 24.8 ± 5.2 years) and 18 older (mean age: 68.8 ± 3.7 years) adults executed a designated force-matching task from a stabilometer board using either a stabilometer stance (posture-focus strategy) or force-matching (supraposture-focus strategy) as the primary task. The dual-task effect (DTE: % change in dual-task condition; positive value: dual-task benefit, negative value: dual-task cost) of force-matching error and reaction time (RT), posture error, and approximate entropy (ApEn) of stabilometer movement were measured. When using the supraposture-focus strategy, young adults exhibited larger DTE values in each behavioral parameter than when using the posture-focus strategy. The older adults using the supraposture-focus strategy also attained larger DTE values for posture error, stabilometer movement ApEn, and force-matching error than when using the posture-focus strategy. These results suggest that the supraposture-focus strategy exerted an increased dual-task benefit for posture-motor dual-tasking in both healthy young and elderly adults. The present findings imply that the older adults should make use of the supraposture-focus strategy for fall prevention during dual-task execution. PMID:28151943

Improving posture-motor dual-task with a supraposture-focus strategy in young and elderly adults.

PubMed

Yu, Shu-Han; Huang, Cheng-Ya

2017-01-01

In a postural-suprapostural task, appropriate prioritization is necessary to achieve task goals and maintain postural stability. A "posture-first" principle is typically favored by elderly people in order to secure stance stability, but this comes at the cost of reduced suprapostural performance. Using a postural-suprapostural task with a motor suprapostural goal, this study investigated differences between young and older adults in dual-task cost across varying task prioritization paradigms. Eighteen healthy young (mean age: 24.8 ± 5.2 years) and 18 older (mean age: 68.8 ± 3.7 years) adults executed a designated force-matching task from a stabilometer board using either a stabilometer stance (posture-focus strategy) or force-matching (supraposture-focus strategy) as the primary task. The dual-task effect (DTE: % change in dual-task condition; positive value: dual-task benefit, negative value: dual-task cost) of force-matching error and reaction time (RT), posture error, and approximate entropy (ApEn) of stabilometer movement were measured. When using the supraposture-focus strategy, young adults exhibited larger DTE values in each behavioral parameter than when using the posture-focus strategy. The older adults using the supraposture-focus strategy also attained larger DTE values for posture error, stabilometer movement ApEn, and force-matching error than when using the posture-focus strategy. These results suggest that the supraposture-focus strategy exerted an increased dual-task benefit for posture-motor dual-tasking in both healthy young and elderly adults. The present findings imply that the older adults should make use of the supraposture-focus strategy for fall prevention during dual-task execution.

Effects of 30-, 60-, and 90-Day Bed Rest on Postural Control in Men and Women

NASA Technical Reports Server (NTRS)

Esteves, Julie; Taylor, Laura C.; Vanya, Robert D.; Dean, S. Lance; Wood, Scott J.

2011-01-01

INTRODUCTION Head-down-tilt bed rest (HDT) has been used as a safe gr ound-based analog to mimic and develop countermeasures for the physiological effects of spaceflight, including decrements in postural stability. The purpose of this investigation was to characterize the effects of 30-, 60-, and 90-day bed rest on postural control in men and women. METHODS Twenty-nine subjects (18M,11F) underwent 13 days of ambula tory acclimatization and were placed in 6? HDT for 30 (n=12), 60 (n=8), or 90 (n=9) days, followed by 14 days of ambulatory recovery. Computerized dynamic posturography (CDP) was used to assess changes in sensory and motor components of postural control, and recovery after HDT. Sensory Organization Tests (SOTs) objectively evaluate one?s ability to effectively use or suppress visual, vestibular, and proprioceptive information for postural control. Stability during the SOTs was assessed using peak-to-peak sway and convergence toward stability limits to derive an equilibrium score. Motor Control Tests (MCTs) evaluate one?s ability to recover from unexpected support surface perturbations, with performance determined by center-of-pressure path length. Whole-body kinematic data were collected to determine body-sway strategy used to maintain stability during each condition. Baselines were determined pre-HDT. Recovery was tracked post-HDT on days 0, 1, 2, and 4. RESULTS Immediately after HDT, subjects showed decreased performance on most SOTs, primarily on sway-referenced support conditions, typically returning to baseline levels within 4 days. MCT performance was not significantly affected. There were no significant gender or duration differences in performance. Kinematic data revealed a tendency to use ankle strategy to maintain an upright stance during most SOT conditions. Interestingly, six subjects (2M,4F) experienced orthostatic intolerance and were unable to complete day 0 testing. CONCLUSION HDT mimics some un loading mechanisms of spaceflight and elicits orthostatic issues present post-spaceflight (contributing to instability); however, it does not sufficiently address the vestibular dysfunction which occurs post-spaceflight.

The effects of balance and postural stability exercises on spa based rehabilitation programme in patients with ankylosing spondylitis.

PubMed

Gunay, Selim M; Keser, Ilke; Bicer, Zemzem T

2018-01-01

Ankylosing spondylitis (AS) can cause severe functional disorders that lead to loss of balance. The aim of this study was to investigate the effects of balance and postural stability exercises on spa based rehabilitation programme in AS subjects. Twenty-one participants were randomized to the study (n= 11) and control groups (n= 10). Patients balance and stability were assessed with the Berg Balance Scale (BBS), Timed Up and Go (TUG) Test, Single Leg Stance Test (SLST) and Functional Reach Test (FRT). AS spesicied measures were used for assessing to other parameters. The treatment plan for both groups consisted of conventional transcutaneous electrical nerve stimulation (TENS), spa and land-based exercises 5 days per week for 3 weeks. The study group performed exercises based on postural stability and balance with routine physiotherapy practice in thermal water and in exercise room. The TUG, SLST and FUT scores were significantly increased in the study group. In both groups, the BASMI, BASFI, BASDAI and ASQoL scores decreased significantly by the end of the treatment period (p< 0.05). In AS rehabilitation, performing balance and stability exercises in addition to spa based routine approaches can increase the duration of maintaining balance and can improve the benefits of physiotherapy.

Unipedal postural stability in nonathletes with core instability after intensive abdominal drawing-in maneuver.

PubMed

Lee, Nam G; You, Joshua Sung H; Kim, Tae H; Choi, Bong S

2015-02-01

The exact neuromechanical nature and relative contribution of the abdominal drawing-in maneuver (ADIM) to postural instability warrants further investigation in uninjured and injured populations. To determine the effects of the ADIM on static core and unipedal postural stability in nonathletes with core instability. Controlled laboratory study. University research laboratory. A total of 19 nonathletes (4 women: age = 22.3 ± 1.3 years, height = 164.0 ± 1.7 cm, mass = 56.0 ± 4.6 kg; 15 men: age = 24.6 ± 2.8 years, height = 172.6 ± 4.7 cm, mass = 66.8 ± 7.6 kg) with core instability. Participants received ADIM training with visual feedback 20 minutes each day for 7 days each week over a 2-week period. Core instability was determined using a prone formal test and measured by a pressure biofeedback unit. Unipedal postural stability was determined by measuring the center-of-pressure sway and associated changes in the abdominal muscle-thickness ratios. Electromyographic activity was measured concurrently in the external oblique, erector spinae, gluteus medius, vastus medialis oblique, tibialis anterior, and medial gastrocnemius muscles. All participants initially were unable to complete the formal test. However, after the 2-week ADIM training period, all participants were able to reduce the pressure biofeedback unit by a range of 4 to 10 mm Hg from an initial 70 mm Hg and maintain it at 60 to 66 mm Hg with minimal activation of the external oblique (t(18) = 3.691, P = .002) and erector spinae (t(18) = 2.823, P = .01) muscles. Monitoring of the pressure biofeedback unit and other muscle activations confirmed that the correct muscle contraction defining the ADIM was accomplished. This core stabilization was well maintained in the unipedal-stance position, as evidenced by a decrease in the center-of-pressure sway measures (t(18) range, 3.953-5.775, P < .001), an increased muscle-thickness ratio for the transverse abdominis (t(18) = -2.327, P = .03), and a reduction in external oblique muscle activity (t(18) = 3.172, P = .005). We provide the first evidence to highlight the positive effects of ADIM training on core and postural stability in nonathletes with core instability.

Intensive Abdominal Drawing-In Maneuver After Unipedal Postural Stability in Nonathletes With Core Instability

PubMed Central

Lee, Nam G.; You, Joshua (Sung) H.; Kim, Tae H.; Choi, Bong S.

2015-01-01

Context: The exact neuromechanical nature and relative contribution of the abdominal drawing-in maneuver (ADIM) to postural instability warrants further investigation in uninjured and injured populations. Objective: To determine the effects of the ADIM on static core and unipedal postural stability in nonathletes with core instability. Design: Controlled laboratory study. Setting: University research laboratory. Patients or Other Participants: A total of 19 nonathletes (4 women: age = 22.3 ± 1.3 years, height = 164.0 ± 1.7 cm, mass = 56.0 ± 4.6 kg; 15 men: age = 24.6 ± 2.8 years, height = 172.6 ± 4.7 cm, mass = 66.8 ± 7.6 kg) with core instability. Intervention(s): Participants received ADIM training with visual feedback 20 minutes each day for 7 days each week over a 2-week period. Main Outcome Measures(s): Core instability was determined using a prone formal test and measured by a pressure biofeedback unit. Unipedal postural stability was determined by measuring the center-of-pressure sway and associated changes in the abdominal muscle-thickness ratios. Electromyographic activity was measured concurrently in the external oblique, erector spinae, gluteus medius, vastus medialis oblique, tibialis anterior, and medial gastrocnemius muscles. Results: All participants initially were unable to complete the formal test. However, after the 2-week ADIM training period, all participants were able to reduce the pressure biofeedback unit by a range of 4 to 10 mm Hg from an initial 70 mm Hg and maintain it at 60 to 66 mm Hg with minimal activation of the external oblique (t18 = 3.691, P = .002) and erector spinae (t18 = 2.823, P = .01) muscles. Monitoring of the pressure biofeedback unit and other muscle activations confirmed that the correct muscle contraction defining the ADIM was accomplished. This core stabilization was well maintained in the unipedal-stance position, as evidenced by a decrease in the center-of-pressure sway measures (t18 range, 3.953–5.775, P < .001), an increased muscle-thickness ratio for the transverse abdominis (t18 = −2.327, P = .03), and a reduction in external oblique muscle activity (t18 = 3.172, P = .005). Conclusions: We provide the first evidence to highlight the positive effects of ADIM training on core and postural stability in nonathletes with core instability. PMID:25531145

The effect of resistance level and stability demands on recruitment patterns and internal loading of spine in dynamic flexion and extension using a simple trunk model.

PubMed

Zeinali-Davarani, Shahrokh; Shirazi-Adl, Aboulfazl; Dariush, Behzad; Hemami, Hooshang; Parnianpour, Mohamad

2011-07-01

The effects of external resistance on the recruitment of trunk muscles in sagittal movements and the coactivation mechanism to maintain spinal stability were investigated using a simple computational model of iso-resistive spine sagittal movements. Neural excitation of muscles was attained based on inverse dynamics approach along with a stability-based optimisation. The trunk flexion and extension movements between 60° flexion and the upright posture against various resistance levels were simulated. Incorporation of the stability constraint in the optimisation algorithm required higher antagonistic activities for all resistance levels mostly close to the upright position. Extension movements showed higher coactivation with higher resistance, whereas flexion movements demonstrated lower coactivation indicating a greater stability demand in backward extension movements against higher resistance at the neighbourhood of the upright posture. Optimal extension profiles based on minimum jerk, work and power had distinct kinematics profiles which led to recruitment patterns with different timing and amplitude of activation.

Postural Stability in Healthy Child and Youth Athletes: The Effect of Age, Sex, and Concussion-Related Factors on Performance.

PubMed

Paniccia, Melissa; Wilson, Katherine E; Hunt, Anne; Keightley, Michelle; Zabjek, Karl; Taha, Tim; Gagnon, Isabelle; Reed, Nick

Postural stability plays a key role in sport performance, especially after concussion. Specific to healthy child and youth athletes, little is known about the influence development and sex may have on postural stability while considering other subjective clinical measures used in baseline/preinjury concussion assessment. This study aims to describe age- and sex-based trends in postural stability in uninjured child and youth athletes at baseline while accounting for concussion-related factors. (1) Postural stability performance will improve with age, (2) females will display better postural stability compared to males, and (3) concussion-like symptoms will affect postural stability performance in healthy children and youth. Cross-sectional study. Level 3. This study comprised 889 healthy/uninjured child and youth athletes (54% female, 46% male) between the ages of 9 and 18 years old. Participants completed preseason baseline testing, which included demographic information (age, sex, concussion history), self-report of concussion-like symptoms (Post-Concussion Symptom Inventory [PCSI]-Child and PCSI-Youth), and measures of postural stability (BioSway; Biodex Medical Systems). Two versions of the PCSI were used (PCSI-C, 9- to 12-year-olds; PCSI-Y, 13- to 18-year-olds). Postural stability was assessed via sway index under 4 sway conditions of increasing difficulty by removing visual and proprioceptive cues. In children aged 9 to 12 years old, there were significant age- ( P < 0.05) and sex-based effects ( P < 0.05) on postural stability. Performance improved with age, and girls performed better than boys. For youth ages 13 to 18 years old, postural stability also improved with age ( P < 0.05). In both child and youth subgroups, postural stability worsened with increasing concussion-like symptoms ( P < 0.05). There are developmental and baseline symptom trends regarding postural stability performance. These findings provide a preliminary foundation for postconcussion comparisons and highlight the need for a multimodal approach in assessing and understanding physical measures such as postural stability.

Haptic cues for orientation and postural control in sighted and blind individuals

NASA Technical Reports Server (NTRS)

Jeka, J. J.; Easton, R. D.; Bentzen, B. L.; Lackner, J. R.

1996-01-01

Haptic cues from fingertip contact with a stable surface attenuate body sway in subjects even when the contact forces are too small to provide physical support of the body. We investigated how haptic cues derived from contact of a cane with a stationary surface at low force levels aids postural control in sighted and congenitally blind individuals. Five sighted (eyes closed) and five congenitally blind subjects maintained a tandem Romberg stance in five conditions: (1) no cane; (2,3) touch contact (< 2 N of applied force) while holding the cane in a vertical or slanted orientation; and (4,5) force contact (as much force as desired) in the vertical and slanted orientations. Touch contact of a cane at force levels below those necessary to provide significant physical stabilization was as effective as force contact in reducing postural sway in all subjects, compared to the no-cane condition. A slanted cane was far more effective in reducing postural sway than was a perpendicular cane. Cane use also decreased head displacement of sighted subjects far more than that of blind subjects. These results suggest that head movement control is linked to postural control through gaze stabilization reflexes in sighted subjects; such reflexes are absent in congenitally blind individuals and may account for their higher levels of head displacement.

Postural orientation and equilibrium processes associated with increased postural sway in autism spectrum disorder (ASD).

PubMed

Wang, Zheng; Hallac, Rami R; Conroy, Kaitlin C; White, Stormi P; Kane, Alex A; Collinsworth, Amy L; Sweeney, John A; Mosconi, Matthew W

2016-01-01

Increased postural sway has been repeatedly documented in children with autism spectrum disorder (ASD). Characterizing the control processes underlying this deficit, including postural orientation and equilibrium, may provide key insights into neurophysiological mechanisms associated with ASD. Postural orientation refers to children's ability to actively align their trunk and head with respect to their base of support, while postural equilibrium is an active process whereby children coordinate ankle dorsi-/plantar-flexion and hip abduction/adduction movements to stabilize their upper body. Dynamic engagement of each of these control processes is important for maintaining postural stability, though neither postural orientation nor equilibrium has been studied in ASD. Twenty-two children with ASD and 21 age and performance IQ-matched typically developing (TD) controls completed three standing tests. During static stance, participants were instructed to stand as still as possible. During dynamic stances, participants swayed at a comfortable speed and magnitude in either anterior-posterior (AP) or mediolateral (ML) directions. The center of pressure (COP) standard deviation and trajectory length were examined to determine if children with ASD showed increased postural sway. Postural orientation was assessed using a novel virtual time-to-contact (VTC) approach that characterized spatiotemporal dimensions of children's postural sway (i.e., body alignment) relative to their postural limitation boundary, defined as the maximum extent to which each child could sway in each direction. Postural equilibrium was quantified by evaluating the amount of shared or mutual information of COP time series measured along the AP and ML directions. Consistent with prior studies, children with ASD showed increased postural sway during both static and dynamic stances relative to TD children. In regard to postural orientation processes, children with ASD demonstrated reduced spatial perception of their postural limitation boundary towards target directions and reduced time to correct this error during dynamic postural sways but not during static stance. Regarding postural equilibrium, they showed a compromised ability to decouple ankle dorsi-/plantar-flexion and hip abduction/adduction processes during dynamic stances. These results suggest that deficits in both postural orientation and equilibrium processes contribute to reduced postural stability in ASD. Specifically, increased postural sway in ASD appears to reflect patients' impaired perception of their body movement relative to their own postural limitation boundary as well as a reduced ability to decouple distinct ankle and hip movements to align their body during standing. Our findings that deficits in postural orientation and equilibrium are more pronounced during dynamic compared to static stances suggests that the increased demands of everyday activities in which children must dynamically shift their COP involve more severe postural control deficits in ASD relative to static stance conditions that often are studied. Systematic assessment of dynamic postural control processes in ASD may provide important insights into new treatment targets and neurodevelopmental mechanisms.

The effect of vision on postural strategies in Prader-Willi patients.

PubMed

Cimolin, Veronica; Galli, Manuela; Vismara, Luca; Grugni, Graziano; Priano, Lorenzo; Capodaglio, Paolo

2011-01-01

The aim of this study was to quantify the role of visual contribution in patients with Prader-Willi syndrome (PWS) on balance maintenance using a force platform. We enrolled 14 individuals with PWS free from conditions associated with impaired balance, 44 obese (OG) and 20 healthy controls (CG). Postural sway was measured for 60s while standing on a force platform (Kistler, CH; acquisition frequency: 500 Hz) integrated with a video system. Patients maintained an upright standing position with Open Eyes (OE) and then with Closed Eyes (CE). The ratio between the value of the parameter under OE and CE conditions was measured. Under OE condition PWS and OG were characterized by higher postural instability than CG, with the PWS group showing poorer balance capacity than OG. The Romberg ratio showed that while OG and CG had lower balance without vision, PWS maintained the same performance changing from OE to CE. The integration of different sensory inputs appears similar in OG and CG with higher postural stability under OE than CE. Balance in PWS is not influenced by the elimination of visual input. Copyright © 2011 Elsevier Ltd. All rights reserved.

Stiffness and Damping in Postural Control Increase with Age

PubMed Central

Cenciarini, Massimo; Loughlin, Patrick J.; Sparto, Patrick J.; Redfern, Mark S.

2011-01-01

Upright balance is believed to be maintained through active and passive mechanisms, both of which have been shown to be impacted by aging. A compensatory balance response often observed in older adults is increased co-contraction, which is generally assumed to enhance stability by increasing joint stiffness. We investigated the effect of aging on standing balance by fitting body sway data to a previously-developed postural control model that includes active and passive stiffness and damping parameters. Ten young (24 ± 3 y) and seven older (75 ± 5 y) adults were exposed during eyes-closed stance to perturbations consisting of lateral pseudorandom floor tilts. A least-squares fit of the measured body sway data to the postural control model found significantly larger active stiffness and damping model parameters in the older adults. These differences remained significant even after normalizing to account for different body sizes between the young and older adult groups. An age effect was also found for the normalized passive stiffness, but not for the normalized passive damping parameter. This concurrent increase in active stiffness and damping was shown to be more stabilizing than an increase in stiffness alone, as assessed by oscillations in the postural control model impulse response. PMID:19770083

Trunk muscle activity increases with unstable squat movements.

PubMed

Anderson, Kenneth; Behm, David G

2005-02-01

The objective of this study was to determine differences in electromyographic (EMG) activity of the soleus (SOL), vastus lateralis (VL), biceps femoris (BF), abdominal stabilizers (AS), upper lumbar erector spinae (ULES), and lumbo-sacral erector spinae (LSES) muscles while performing squats of varied stability and resistance. Stability was altered by doing the squat movement on a Smith machine, a free squat, and while standing on two balance discs. Fourteen male subjects performed the movements. Activities of the SOL, AS, ULES, and LSES were highest during the unstable squat and lowest with the Smith machine protocol (p < 0.05). Increased EMG activity of these muscles may be attributed to their postural and stabilization role. Furthermore, EMG activity was higher during concentric contractions compared to eccentric contractions. Performing squats on unstable surfaces may permit a training adaptation of the trunk muscles responsible for supporting the spinal column (i.e., erector spinae) as well as the muscles most responsible for maintaining posture (i.e., SOL).

Normative Data for the NeuroCom Sensory Organization Test in US Military Special Operations Forces

PubMed Central

Pletcher, Erin R.; Williams, Valerie J.; Abt, John P.; Morgan, Paul M.; Parr, Jeffrey J.; Wohleber, Meleesa F.; Lovalekar, Mita; Sell, Timothy C.

2017-01-01

Context: Postural stability is the ability to control the center of mass in relation to a person's base of support and can be affected by both musculoskeletal injury and traumatic brain injury. The NeuroCom Sensory Organization Test (SOT) can be used to objectively quantify impairments to postural stability. The ability of postural stability to predict injury and be used as an acute injury-evaluation tool makes it essential to the screening and rehabilitation process. To our knowledge, no published normative data for the SOT from a healthy, highly active population are available for use as a reference for clinical decision making. Objective: To present a normative database of SOT scores from a US Military Special Operations population that can be used for future comparison. Design: Cross-sectional study. Setting: Human performance research laboratory. Patients or Other Participants: A total of 542 active military operators from Naval Special Warfare Combatant-Craft Crewmen (n = 149), Naval Special Warfare Command, Sea, Air, and Land (n = 101), US Army Special Operations Command (n = 171), and Air Force Special Operations Command (n = 121). Main Outcome Measure(s): Participants performed each of the 6 SOT conditions 3 times. Scores for each condition, total equilibrium composite score, and ratio scores for the somatosensory, visual, and vestibular systems were recorded. Results: Differences were present across all groups for SOT conditions 1 (P < .001), 2 (P = .001), 4 (P > .001), 5 (P > .001), and 6 (P = .001) and total equilibrium composite (P = .000), visual (P > .001), vestibular (P = .002), and preference (P > .001) NeuroCom scores. Conclusions: Statistical differences were evident in the distribution of postural stability across US Special Operations Forces personnel. This normative database for postural stability, as assessed by the NeuroCom SOT, can provide context when clinicians assess a Special Operations Forces population or any other groups that maintain a high level of conditioning and training. PMID:28140624

Normative Data for the NeuroCom Sensory Organization Test in US Military Special Operations Forces.

PubMed

Pletcher, Erin R; Williams, Valerie J; Abt, John P; Morgan, Paul M; Parr, Jeffrey J; Wohleber, Meleesa F; Lovalekar, Mita; Sell, Timothy C

2017-02-01

Postural stability is the ability to control the center of mass in relation to a person's base of support and can be affected by both musculoskeletal injury and traumatic brain injury. The NeuroCom Sensory Organization Test (SOT) can be used to objectively quantify impairments to postural stability. The ability of postural stability to predict injury and be used as an acute injury-evaluation tool makes it essential to the screening and rehabilitation process. To our knowledge, no published normative data for the SOT from a healthy, highly active population are available for use as a reference for clinical decision making. To present a normative database of SOT scores from a US Military Special Operations population that can be used for future comparison. Cross-sectional study. Human performance research laboratory. A total of 542 active military operators from Naval Special Warfare Combatant-Craft Crewmen (n = 149), Naval Special Warfare Command, Sea, Air, and Land (n = 101), US Army Special Operations Command (n = 171), and Air Force Special Operations Command (n = 121). Participants performed each of the 6 SOT conditions 3 times. Scores for each condition, total equilibrium composite score, and ratio scores for the somatosensory, visual, and vestibular systems were recorded. Differences were present across all groups for SOT conditions 1 (P < .001), 2 (P = .001), 4 (P > .001), 5 (P > .001), and 6 (P = .001) and total equilibrium composite (P = .000), visual (P > .001), vestibular (P = .002), and preference (P > .001) NeuroCom scores. Statistical differences were evident in the distribution of postural stability across US Special Operations Forces personnel. This normative database for postural stability, as assessed by the NeuroCom SOT, can provide context when clinicians assess a Special Operations Forces population or any other groups that maintain a high level of conditioning and training.

Characterization of postural control deficit in whiplash patients by means of linear and nonlinear analyses - A pilot study.

PubMed

Madeleine, Pascal; Nielsen, Mogens; Arendt-Nielsen, Lars

2011-04-01

The ability to maintain balance is diminished in patients suffering from a whiplash injury. The aim of this study was to characterize the variability of postural control in patients with chronic whiplash injury. For this purpose, we analyzed static postural recordings from 11 whiplash patients and sex- and age-matched asymptomatic healthy volunteers. Static postural recordings were performed randomly with eyes open, eyes closed, and eyes open and speaking (dual task). Spatial-temporal changes of the center of pressure displacement were analyzed to assess the amplitude and structure of postural variability by computing, respectively, the standard deviation/coefficient of variation and sample entropy/fractal dimension of the time series. The amplitude of variability of the center of pressure was larger among whiplash patients compared with controls (P<0.001) while fractal dimension was lower (P<0.001). The sample entropy increased during both eyes closed and a simple dual task compared with eyes open (P<0.05). The analysis of postural control dynamics revealed increased amplitude of postural variability and decreased signal dimensionality related to the deficit in postural stability found in whiplash patients. Linear and nonlinear analyses can thus be helpful for the quantification of postural control in normal and pathological conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

Trunk muscle exercises as a means of improving postural stability in people with Parkinson's disease: a protocol for a randomised controlled trial.

PubMed

Hubble, Ryan P; Naughton, Geraldine A; Silburn, Peter A; Cole, Michael H

2014-12-31

Exercise has been shown to improve clinical measures of strength, balance and mobility, and in some cases, has improved symptoms of tremor and rigidity in people with Parkinson's disease (PD). However, to date, no research has examined whether improvements in trunk control can remedy deficits in dynamic postural stability in this population. The proposed randomised controlled trial aims to establish whether a 12-week exercise programme aimed at improving dynamic postural stability in people with PD; (1) is more effective than education; (2) is more effective when training frequency is increased; and (3) provides greater long-term benefits than education. Forty-five community-dwelling individuals diagnosed with idiopathic PD with a falls history will be recruited. Participants will complete baseline assessments including tests of cognition, vision, disease severity, fear of falling, mobility and quality of life. Additionally, participants will complete a series of standing balance tasks to evaluate static postural stability, while dynamic postural control will be measured during walking using head and trunk-mounted three-dimensional accelerometers. Following baseline testing, participants will be randomly-assigned to one of three intervention groups, who will receive either exercise once per week, exercise 3 days/week, or education. Participants will repeat the same battery of tests conducted at baseline after the 12-week intervention and again following a further 12-week sustainability period. This study has the potential to show that low-intensity and progressive trunk exercises can provide a non-invasive and effective means for maintaining or improving postural stability for people with PD. Importantly, if the programme is noted to be effective, it could be easily performed by patients within their home environment or under the guidance of available allied health professionals. The protocol for this study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12613001175763). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Influence of Electrotactile Tongue Feedback on Controlling Upright Stance during Rotational and/or Translational Sway-referencing with Galvanic Vestibular Stimulation

NASA Technical Reports Server (NTRS)

Wood, Scott J.; Tyler, Mitchell E.; Bach-y-Rita, Paul; MacDougall, Hamish G.; Moore, Steven T.; Stallings, Valerie L.; Paloski, William H.; Black, F. Owen

2007-01-01

Integration of multi-sensory inputs to detect tilts relative to gravity is critical for sensorimotor control of upright orientation. Displaying body orientation using electrotactile feedback to the tongue has been developed by Bach-y-Rita and colleagues as a sensory aid to maintain upright stance with impaired vestibular feedback. MacDougall et al. (2006) recently demonstrated that unpredictably varying Galvanic vestibular stimulation (GVS) significantly increased anterior-posterior (AP) sway during rotational sway referencing with eyes closed. The purpose of this study was to assess the influence of electrotactile feedback on postural control performance with pseudorandom binaural bipolar GVS. Postural equilibrium was measured with a computerized hydraulic platform in 10 healthy adults (6M, 4F, 24-65 y). Tactile feedback (TF) of pitch and roll body orientation was derived from a two-axis linear accelerometer mounted on a torso belt and displayed on a 144-point electrotactile array held against the anterior dorsal tongue (BrainPort, Wicab, Inc., Middleton, WI). Subjects were trained to use TF by voluntarily swaying to draw figures on their tongue, both with and without GVS. Subjects were required to keep the intraoral display in their mouths on all trials, including those that did not provide TF. Subjects performed 24 randomized trials (20 s duration with eyes closed) including four support surface conditions (fixed, rotational sway-referenced, translating the support surface proportional to AP sway, and combined rotational-translational sway-referencing), each repeated twice with and without GVS, and with combined GVS and TF. Postural performance was assessed using deviations from upright (peak-to-peak and RMS sway) and convergence toward stability limits (time and distance to base of support boundaries). Postural stability was impaired with GVS in all platform conditions, with larger decrements in performance during trials with rotation sway-referencing. Electrotactile feedback improved performance with GVS toward non-GVS levels, again with the greatest improvement during trials with rotation sway-referencing. These results demonstrate the effectiveness of tongue electrotactile feedback in providing sensory substitution to maintain postural stability with distorted vestibular input.

Use of motor abundance in old adults in the regulation of a narrow-based stance.

PubMed

Hsu, Wei-Li; Lin, Kwan-Hwa; Yang, Rong-Sen; Cheng, Chih-Hsiu

2014-02-01

The ability to maintain stable balance while standing decreases with age. The body must coordinate multiple joints using "freeze" or "free" strategy, or a combination of both to ensure balance stability. The purpose of this study was to examine age-related changes in the use of motor abundance during upright stance on a narrow base without visual input. Uncontrolled manifold (UCM) analysis was used to decompose the movement variability of joints into goal-equivalent variability (GEV) and non-goal-equivalent variability (NGEV). The ratio between GEV and NGEV (UCM(ratio)) quantifies the joint coordination related to postural stability, and a high UCM(ratio) value indicates flexible control of joints. To perform balance tests, participants in this study (healthy young and old adults, 20 each) were asked to stand on a flat platform and on narrow wooden blocks with their eyes open and then eyes closed. In upright balance tests, both old and young adults maintained postural stability. GEV was greater than NGEV across all participants and conditions. However, GEV was higher in the young adults than in the old adults, whereas NGEV was higher in the old adults than in the young adults. Therefore, the old adults exhibited a lower UCM(ratio) than the young adults. The old adults were unable to exploit motor abundance and used a less flexible multi-joint coordination pattern to achieve stable balance. The UCM(ratio) value reflects the quality of postural control and can be used for assessing joint coordination in balance disorders.

Asymmetric interjoint feedback contributes to postural control of redundant multi-link systems

NASA Astrophysics Data System (ADS)

Bunderson, Nathan E.; Ting, Lena H.; Burkholder, Thomas J.

2007-09-01

Maintaining the postural configuration of a limb such as an arm or leg is a fundamental neural control task that involves the coordination of multiple linked body segments. Biological systems are known to use a complex network of inter- and intra-joint feedback mechanisms arising from muscles, spinal reflexes and higher neuronal structures to stabilize the limbs. While previous work has shown that a small amount of asymmetric heterogenic feedback contributes to the behavior of these systems, a satisfactory functional explanation for this non-conservative feedback structure has not been put forth. We hypothesized that an asymmetric multi-joint control strategy would confer both an energetic and stability advantage in maintaining endpoint position of a kinematically redundant system. We tested this hypothesis by using optimal control models incorporating symmetric versus asymmetric feedback with the goal of maintaining the endpoint location of a kinematically redundant, planar limb. Asymmetric feedback improved endpoint control performance of the limb by 16%, reduced energetic cost by 21% and increased interjoint coordination by 40% compared to the symmetric feedback system. The overall effect of the asymmetry was that proximal joint motion resulted in greater torque generation at distal joints than vice versa. The asymmetric organization is consistent with heterogenic stretch reflex gains measured experimentally. We conclude that asymmetric feedback has a functionally relevant role in coordinating redundant degrees of freedom to maintain the position of the hand or foot.

Asymmetric interjoint feedback contributes to postural control of redundant multi-link systems

PubMed Central

Bunderson, Nathan E.; Ting, Lena H.; Burkholder, Thomas J.

2008-01-01

Maintaining the postural configuration of a limb such as an arm or leg is a fundamental neural control task that involves the coordination of multiple linked body segments. Biological systems are known to use a complex network of inter- and intra-joint feedback mechanisms arising from muscles, spinal reflexes, and higher neuronal structures to stabilize the limbs. While previous work has shown that a small amount of asymmetric heterogenic feedback contributes to the behavior of these systems, a satisfactory functional explanation for this nonconservative feedback structure has not been put forth. We hypothesized that an asymmetric multi-joint control strategy would confer both an energetic and stability advantage in maintaining endpoint position of a kinematically redundant system. We tested this hypothesis by using optimal control models incorporating symmetric versus asymmetric feedback with the goal of maintaining the endpoint location of a kinematically redundant, planar limb. Asymmetric feedback improved endpoint control performance of the limb by 16%, reduced energetic cost by 21% and increased interjoint coordination by 40% compared to the symmetric feedback system. The overall effect of the asymmetry was that proximal joint motion resulted in greater torque generation at distal joints than vice versa. The asymmetric organization is consistent with heterogenic stretch reflex gains measured experimentally. We conclude that asymmetric feedback has a functionally relevant role in coordinating redundant degrees of freedom to maintain the position of the hand or foot. PMID:17873426

Postural Stability in Older Adults With Alzheimer Disease.

PubMed

Mesbah, Normala; Perry, Meredith; Hill, Keith D; Kaur, Mandeep; Hale, Leigh

2017-03-01

The prevalence of adults with Alzheimer disease (AD) aged >65 years is increasing and estimated to quadruple by 2051. The aim of this study was to investigate postural stability in people with mild to moderate AD and factors contributing to postural instability compared with healthy peers (controls). A computerized systematic search of databases and a hand search of reference lists for articles published from 1984 onward (English-language articles only) were conducted on June 2, 2015, using the main key words "postural stability" and "Alzheimer's disease." Sixty-seven studies were assessed for eligibility (a confirmed diagnosis of AD, comparison of measured postural stability between participants with AD and controls, measured factors potentially contributing to postural instability). Data were extracted, and Downs and Black criteria were applied to evaluate study quality. Eighteen articles were analyzed using qualitative synthesis and reported based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Strength of evidence was guided by the Grading of Recommendations Assessment, Development and Evaluation. Strong evidence was found that: (1) older adults with mild to moderate AD have reduced static and functional postural stability compared with healthy peers (controls) and (2) attentional demand during dual-task activity and loss of visual input were key factors contributing to postural instability. Deta-analysis was not possible due to heterogeneity of the data. Postural stability is impaired in older adults with mild to moderate AD. Decreasing visual input and concentrating on multiple tasks decrease postural stability. To reduce falls risk, more research discerning appropriate strategies for the early identification of impairment of postural stability is needed. Standardization of population description and consensus on outcome measures and the variables used to measure postural -instability and its contributing factors are necessary to ensure meaningful synthesis of data. © 2017 American Physical Therapy Association

Postural steadiness and ankle force variability in peripheral neuropathy

PubMed Central

Paxton, Roger J.; Feldman-Kothe, Caitlin; Trabert, Megan K.; Hitchcock, Leah N.; Reiser, Raoul F.; Tracy, Brian L.

2015-01-01

Introduction The purpose was to determine the effect of peripheral neuropathy (PN) on motor output variability for ankle muscles of older adults, and the relation between ankle motor variability and postural stability in PN patients. Methods Older adults with (O-PN) and without PN (O), and young adults (Y) underwent assessment of standing postural stability and ankle muscle force steadiness. Results O-PN displayed impaired ankle muscle force control and postural stability compared with O and Y groups. For O-PN, the amplitude of plantarflexor force fluctuations was moderately correlated with postural stability under no-vision conditions (r = 0.54, P = 0.01). Discussion The correlation of variations in ankle force with postural stability in PN suggests a contribution of ankle muscle dyscontrol to the postural instability that impacts physical function for older adults with PN. PMID:26284897

Postural stability and ankle sprain history in athletes compared to uninjured controls.

PubMed

Huurnink, Arnold; Fransz, Duncan P; Kingma, Idsart; Verhagen, Evert A L M; van Dieën, Jaap H

2014-02-01

Diminished postural stability is a risk factor for ankle sprain occurrence and ankle sprains result in impaired postural stability. To date, ankle sprain history has not been taken into account as a determinant of postural stability, while it could possibly specify subgroups of interest. Postural stability was compared between 18 field hockey athletes who had recovered from an ankle sprain (mean (SD); 3.6 (1.5) months post-injury), and 16 uninjured controls. Force plate and kinematics parameters were calculated during single-leg standing: mean center of pressure speed, mean absolute horizontal ground reaction force, mean absolute ankle angular velocity, and mean absolute hip angular velocity. Additionally, cluster analysis was applied to the 'injured' participants, and the cluster with diminished postural stability was compared to the other participants with respect to ankle sprain history. MANCOVA showed no significant difference between groups in postural stability (P = 0.68). A self-reported history of an (partial) ankle ligament rupture was typically present in the cluster with diminished postural stability. Subsequently, a 'preceding rupture' was added as a factor in the MANCOVA, which showed a significant association between diminished postural stability and a 'preceding rupture' (P = 0.01), for all four individual parameters (P: 0.001-0.029; Cohen's d: 0.96-2.23). Diminished postural stability is not apparent in all previously injured athletes. However, our analysis suggests that an (mild) ankle sprain with a preceding severe ankle sprain is associated with impaired balance ability. Therefore, sensorimotor training may be emphasized in this particular group and caution is warranted in return to play decisions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Low-Back Biomechanics and Static Stability During Isometric Pushing

PubMed Central

Granata, Kevin P.; Bennett, Bradford C.

2006-01-01

Pushing and pulling tasks are increasingly prevalent in industrial workplaces. Few studies have investigated low-back biomechanical risk factors associated with pushing, and we are aware of none that has quantified spinal stability during pushing exertions. Data recorded from 11 healthy participants performing isometric pushing exertions demonstrated that trunk posture, vector force direction of the applied load, and trunk moment were influenced (p < .01) by exertion level, elevation of the handle for the pushing task, and foot position. A biomechanical model was used to analyze the posture and hand force data gathered from the pushing exertions. Model results indicate that pushing exertions provide significantly (p < .01) less stability than lifting when antagonistic cocontraction is ignored. However, stability can be augmented by recruitment of muscle cocontraction. Results suggest that cocontraction may be recruited to compensate for the fact that equilibrium mechanics provide little intrinsic trunk stiffness and stability during pushing exertions. If one maintains stability by means of cocontraction, additional spinal load is thereby created, increasing the risk of overload injury. Thus it is important to consider muscle cocontraction when evaluating the biomechanics of pushing exertions. Potential applications of this research include improved assessment of biomechanical risk factors for the design of industrial pushing tasks. PMID:16435695

Postural steadiness during quiet stance does not associate with ability to recover balance in older women.

PubMed

Mackey, Dawn C; Robinovitch, Stephen N

2005-10-01

Fall risk depends on ability to maintain balance during daily activities, and on ability to recover balance following a perturbation such as a slip or trip. We examined whether similar neuromuscular variables govern these two domains of postural stability. We conducted experiments with 25 older women (mean age=78 yrs, SD=7 yrs). We acquired measures of postural steadiness during quiet stance (mean amplitude, velocity, and frequency of centre-of-pressure movement when standing with eyes open or closed, on a rigid or compliant surface). We also measured ability to recover balance using the ankle strategy after release from a forward leaning position (based on the maximum release angle where recovery was possible, and corresponding values of reaction time, rate of ankle torque generation, and peak ankle torque). We found that balance recovery variables were not strongly or consistently correlated with postural steadiness variables. The maximum release angle associated with only three of the sixteen postural steadiness variables (mean frequency in rigid, eyes open condition (r=0.36, P=.041), and mean amplitude (r=0.41, P=.038) and velocity (r=0.49, P=.015) in compliant, eyes closed condition). Reaction time and peak torque did not correlate with any steadiness variables, and rate of torque generation correlated moderately with the mean amplitude and velocity of the centre-of-pressure in the compliant, eyes closed condition (r=0.48-0.60). Our results indicate that postural steadiness during quiet stance is not predictive of ability to recover balance with the ankle strategy. Accordingly, balance assessment and fall prevention programs should individually target these two components of postural stability.

Comparison of dynamic postural stability scores between athletes with and without chronic ankle instability during lateral jump landing.

PubMed

Shiravi, Zeinab; Shadmehr, Azadeh; Moghadam, Saeed Talebian; Moghadam, Behrouz Attarbashi

2017-01-01

Many ankle injuries occur while participating in sports that require jumping and landing such as basketball, volleyball and soccer. Most recent studies have investigated dynamic postural stability of patients with chronic ankle instability after landing from a forward jump. The present study aimed to investigate the dynamic postural stability of the athletes who suffer from chronic ankle sprain while landing from a lateral jump. Twelve athletes with self-reported unilateral chronic ankle instability (4 females and 8 males) and 12 matched controls (3 females and 9 males) voluntarily participated in the study. Dynamic postural stability index and its directional indices were measured while performing lateral jump landing test. No differences were found between athletes with and without chronic ankle instability during our landing protocol by means of the dynamic postural stability index and its directional indices. Findings showed that in each group, medial/lateral stability index is significantly higher than anterior/posterior and vertical stability indexes. Findings showed that dynamic postural stability was not significantly different between the two groups. Future studies should examine chronic ankle instability patients with more severe disabilities and expose them to more challenging dynamic balance conditions to further explore postural stability. IIIa.

Postural stability in patients with knee osteoarthritis: comparison with controls and evaluation of relationships between postural stability scores and International Classification of Functioning, Disability and Health components.

PubMed

Hsieh, Ru-Lan; Lee, Wen-Chung; Lo, Min-Tzu; Liao, Wei-Cheng

2013-02-01

To assess the differences in postural stability between patients with knee osteoarthritis and controls without knee osteoarthritis, and to evaluate possible relations between postural stability scores and International Classification of Functioning, Disability and Health (ICF) components. An age-matched, case-controlled trial with a cross-sectional design. A teaching hospital. Patients with knee osteoarthritis (n=73) and age-matched controls (n=60). Data on patients' postural stability and additional health-related variables were collected using various instruments. These included the Hospital Anxiety and Depression Scale, the Multidimensional Fatigue Inventory, the World Health Organization Quality of Life Brief Version, the physical function test (chair-rising time), the Chinese version of the Western Ontario and McMaster Universities Osteoarthritis Index, the Chinese version of the Knee Injury and Osteoarthritis Outcome Score, and the Biodex Stability System. A comparison of postural stability in patients with knee osteoarthritis versus that of controls was performed. The relation between postural stability scores for patients with knee osteoarthritis and ICF components was evaluated. Pearson correlation tests were used to determine the variables that correlated with postural stability among these patients. Patients with knee osteoarthritis displayed lower overall postural stability than controls (scores of 0.7 vs. 0.5, P=.006) and scored lower on the environmental domain of the World Health Organization Quality of Life Brief Version (62.2 vs 66.8, P=.014). For patients with knee osteoarthritis, postural stability was weakly associated with the ICF components of body functions and structures, including pain (r=.33-.34, P=.004), physical fatigue (r=.28, P=.016), and reduced motivation (r=.30, P=.011). Weak to moderate associations between postural stability and the ICF components of activities and participation were found; the relevant ICF variables included reduced activity (r=.38, P=.001), physical domain and function (r=.34-.48, P=.001 to P<.004), activities of daily living (r=.51, P<.001), and sports and recreation (r=.35, P=.003). A moderate association between postural stability and the ICF components of personal and environmental factors was observed, including age (r=.52, P<.001) and quality of life (r=0.4, P=.001). Patients with knee osteoarthritis displayed lower postural stability and achieved lower scores in the environmental domain of quality-of-life measures than did controls. The postural stability of patients with knee osteoarthritis was weakly to moderately associated with the following ICF components: body functions and structures, activities and participation, and personal and environmental factors. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Computerized dynamic posturography: the influence of platform stability on postural control.

PubMed

Palm, Hans-Georg; Lang, Patricia; Strobel, Johannes; Riesner, Hans-Joachim; Friemert, Benedikt

2014-01-01

Postural stability can be quantified using posturography systems, which allow different foot platform stability settings to be selected. It is unclear, however, how platform stability and postural control are mathematically correlated. Twenty subjects performed tests on the Biodex Stability System at all 13 stability levels. Overall stability index, medial-lateral stability index, and anterior-posterior stability index scores were calculated, and data were analyzed using analysis of variance and linear regression analysis. A decrease in platform stability from the static level to the second least stable level was associated with a linear decrease in postural control. The overall stability index scores were 1.5 ± 0.8 degrees (static), 2.2 ± 0.9 degrees (level 8), and 3.6 ± 1.7 degrees (level 2). The slope of the regression lines was 0.17 for the men and 0.10 for the women. A linear correlation was demonstrated between platform stability and postural control. The influence of stability levels seems to be almost twice as high in men as in women.

Intermittent control with ankle, hip, and mixed strategies during quiet standing: a theoretical proposal based on a double inverted pendulum model.

PubMed

Suzuki, Yasuyuki; Nomura, Taishin; Casadio, Maura; Morasso, Pietro

2012-10-07

Human upright posture, as a mechanical system, is characterized by an instability of saddle type, involving both stable and unstable dynamic modes. The brain stabilizes such system by generating active joint torques, according to a time-delayed neural feedback control. What is still unsolved is a clear understanding of the control strategies and the control mechanisms that are used by the central nervous system in order to stabilize the unstable posture in a robust way while maintaining flexibility. Most studies in this direction have been limited to the single inverted pendulum model, which is useful for formalizing fundamental mechanical aspects but insufficient for addressing more general issues concerning neural control strategies. Here we consider a double inverted pendulum model in the sagittal plane with small passive viscoelasticity at the ankle and hip joints. Despite difficulties in stabilizing the double pendulum model in the presence of the large feedback delay, we show that robust and flexible stabilization of the upright posture can be established by an intermittent control mechanism that achieves the goal of stabilizing the body posture according to a "divide and conquer strategy", which switches among different controllers in different parts of the state space of the double inverted pendulum. Remarkably, it is shown that a global, robust stability is achieved even if the individual controllers are unstable and the information exploited for switching from one controller to another is severely delayed, as it happens in biological reality. Moreover, the intermittent controller can automatically resolve coordination among multiple active torques associated with the muscle synergy, leading to the emergence of distinct temporally coordinated active torque patterns, referred to as the intermittent ankle, hip, and mixed strategies during quiet standing, depending on the passive elasticity at the hip joint. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of intermittent feedback control on robustness of human-like postural control system

NASA Astrophysics Data System (ADS)

Tanabe, Hiroko; Fujii, Keisuke; Suzuki, Yasuyuki; Kouzaki, Motoki

2016-03-01

Humans have to acquire postural robustness to maintain stability against internal and external perturbations. Human standing has been recently modelled using an intermittent feedback control. However, the causality inside of the closed-loop postural control system associated with the neural control strategy is still unknown. Here, we examined the effect of intermittent feedback control on postural robustness and of changes in active/passive components on joint coordinative structure. We implemented computer simulation of a quadruple inverted pendulum that is mechanically close to human tiptoe standing. We simulated three pairs of joint viscoelasticity and three choices of neural control strategies for each joint: intermittent, continuous, or passive control. We examined postural robustness for each parameter set by analysing the region of active feedback gain. We found intermittent control at the hip joint was necessary for model stabilisation and model parameters affected the robustness of the pendulum. Joint sways of the pendulum model were partially smaller than or similar to those of experimental data. In conclusion, intermittent feedback control was necessary for the stabilisation of the quadruple inverted pendulum. Also, postural robustness of human-like multi-link standing would be achieved by both passive joint viscoelasticity and neural joint control strategies.

Effect of intermittent feedback control on robustness of human-like postural control system.

PubMed

Tanabe, Hiroko; Fujii, Keisuke; Suzuki, Yasuyuki; Kouzaki, Motoki

2016-03-02

Humans have to acquire postural robustness to maintain stability against internal and external perturbations. Human standing has been recently modelled using an intermittent feedback control. However, the causality inside of the closed-loop postural control system associated with the neural control strategy is still unknown. Here, we examined the effect of intermittent feedback control on postural robustness and of changes in active/passive components on joint coordinative structure. We implemented computer simulation of a quadruple inverted pendulum that is mechanically close to human tiptoe standing. We simulated three pairs of joint viscoelasticity and three choices of neural control strategies for each joint: intermittent, continuous, or passive control. We examined postural robustness for each parameter set by analysing the region of active feedback gain. We found intermittent control at the hip joint was necessary for model stabilisation and model parameters affected the robustness of the pendulum. Joint sways of the pendulum model were partially smaller than or similar to those of experimental data. In conclusion, intermittent feedback control was necessary for the stabilisation of the quadruple inverted pendulum. Also, postural robustness of human-like multi-link standing would be achieved by both passive joint viscoelasticity and neural joint control strategies.

Effect of intermittent feedback control on robustness of human-like postural control system

PubMed Central

Tanabe, Hiroko; Fujii, Keisuke; Suzuki, Yasuyuki; Kouzaki, Motoki

2016-01-01

Humans have to acquire postural robustness to maintain stability against internal and external perturbations. Human standing has been recently modelled using an intermittent feedback control. However, the causality inside of the closed-loop postural control system associated with the neural control strategy is still unknown. Here, we examined the effect of intermittent feedback control on postural robustness and of changes in active/passive components on joint coordinative structure. We implemented computer simulation of a quadruple inverted pendulum that is mechanically close to human tiptoe standing. We simulated three pairs of joint viscoelasticity and three choices of neural control strategies for each joint: intermittent, continuous, or passive control. We examined postural robustness for each parameter set by analysing the region of active feedback gain. We found intermittent control at the hip joint was necessary for model stabilisation and model parameters affected the robustness of the pendulum. Joint sways of the pendulum model were partially smaller than or similar to those of experimental data. In conclusion, intermittent feedback control was necessary for the stabilisation of the quadruple inverted pendulum. Also, postural robustness of human-like multi-link standing would be achieved by both passive joint viscoelasticity and neural joint control strategies. PMID:26931281

Recovery of Posture Stability at Different Foot Placements in Patients Who Underwent Minimally Invasive Total Hip Arthroplasty: A One-Year Follow-Up Study.

PubMed

Chang, Chun-Ju; Lin, Na-Ling; Lee, Mel S; Chern, Jen-Suh

2015-01-01

To understand the progression of recovery in postural stability and physical functioning after patients received the minimally invasive total hip arthroplasty (MTHA), we monitor the pain level, functional capacity, and postural stability before and after operation within one year. In total of 23 subjects in our study, we found out that MTHA was effective in relieving pain in first 2 weeks and restoring the hip joint integrity, but the postural stability was influenced especially in tandem stand in both anterior-posterior and medial-lateral directions. The recovery of postural stability and functional capacity in one year duration fluctuated and no consistent improvement tendency was found. We suggested clinicians designing postsurgery rehabilitation program for consistent and progressive long-term recovery of postural stability and fall prevention to optimize surgical results and prevent undesired postoperative consequences.

Postflight Quiet Stance Stability of Astronauts Following Recovery From a Simulated Fall

NASA Technical Reports Server (NTRS)

Reschke, M. F.; Kofman, I. S.; Fisher, E. A.; Cerisano, J. M.; Lawrence, E. L.; Peters, B. T.; Harm, D. L.; Kulecz, W.; Mulavara, A. P.; Fiedler, M. J.;

Does Kinesiology tape counter exercise-related impairments of balance in the elderly?

PubMed

Hosp, Simona; Csapo, Robert; Heinrich, Dieter; Hasler, Michael; Nachbauer, Werner

2018-05-01

Maintaining balance is an essential requirement for the performance of daily tasks and sporting activities, particularly in older adults to prevent falls and associated injuries. Kinesiology tape has gained great popularity in sports and is frequently used as a tool for performance enhancement. However, there is little research investigating its influence on balance. The purpose of this study was to evaluate the effect of Kinesiology tape on dynamic balance, postural stability and knee proprioception after physical activity in healthy, older adults. Twelve physically active, healthy men aged 63-77 years performed the test on two separate days, with and without Kinesiology tape at the knee joint (prospective intervention with cross-over design). Dynamic balance during an obstacle-crossing task, postural stability in a single-leg stance test, and knee joint position sense as a measure of proprioception were examined before and after 30 min of downhill walking on a treadmill. The influences of taping condition and physical activity on all parameters were statistically tested using factorial ANOVAs. Factorial ANOVA revealed significant time × taping condition interaction effects on all performance parameters (p < 0.05), indicating that the exercise-related changes in dynamic balance, postural stability and knee proprioception differed between the two taping conditions. The deterioration of performance was always greater when no tape was used. This study demonstrated that physical exercise significantly deteriorated dynamic balance, postural stability and knee proprioception in older men. These effects can be attenuated through the usage of Kinesiology tape. By preventing exercise-related impairments of balance, Kinesiology tape might help reduce the risk of sports-associated falls and associated injuries. Copyright © 2018 Elsevier B.V. All rights reserved.

Clinical application of the Panjabi neutral zone hypothesis: the Stabilimax NZ posterior lumbar dynamic stabilization system.

PubMed

Yue, James J; Timm, Jens P; Panjabi, Manohar M; Jaramillo-de la Torre, Jorge

2007-01-15

The neutral zone (NZ) is a region of intervertebral motion around the neutral posture where little resistance is offered by the passive spinal column. The NZ appears to be a clinically important measure of spinal stability function. Its size may increase with injury to the spinal column, which in turn may result in spinal instability or low-back pain. Dynamic stabilization systems are designed to support and stabilize the spine while maintaining range of motion (ROM). The Stabilimax NZ device has been designed to reduce the NZ after spinal injury to treat pain while preserving ROM.

Whiplash-associated disorders affect postural reactions to antero-posterior support surface translations during sitting.

PubMed

Côté, Julie N; Patenaude, Isabelle; St-Onge, Nancy; Fung, Joyce

2009-06-01

Previous studies have shown that individuals with WAD display decreased postural stability during standing and walking tasks. However, their ability to maintain seated upright posture has never been investigated. The objective of this study was to characterize kinematic and electromyographic postural stabilization patterns in individuals with chronic WAD and to compare these patterns with those in an able-bodied control group. Ten individuals with WAD and an age- and gender-matched group of healthy individuals were exposed to sudden forward and backward support surface translations while they were seated. Neck and trunk muscle activity and angular displacements as well as centers of mass (COMs) linear displacements at four levels of the head and trunk were computed. The displacement onset of the combined head, arms and trunk COM was significantly delayed in persons with WAD. However, their peak trunk angles were smaller and were reached sooner. In the WAD group, the activation onset of the lumbar erector spinae was less affected by perturbation direction and the sternocleidomastoid muscle, a neck flexor, showed a trend towards being activated later, compared to the healthy group. These results suggest that individuals with WAD may alter stretch reflex threshold and/or elicit a learned response for pain avoidance that may be direction-specific. Such findings highlight the importance of assessing both spatial and temporal characteristics across different levels of the spinal musculoskeletal system to evaluate multidirectional postural responses in WAD individuals.

Balance ability and postural stability among patients with painful shoulder disorders and healthy controls

PubMed Central

2013-01-01

Background In therapeutic settings, patients with shoulder pain often exhibit deficient coordinative abilities in their trunk and lower extremities. The aim of the study was to investigate 1) if there is a connection between shoulder pain and deficits in balance ability and postural stability, 2) if pain intensity is related to balance ability and postural stability, and 3) if there is a connection between body mass index (BMI) and balance ability and postural stability. Methods In this case–control study, patients (n = 40) with pathological shoulder pain (> 4 months) were matched with a healthy controls (n = 40) and were compared with regard to their balance ability and postural stability. Outcome parameters were postural stability, balance ability and symmetry index which were measured using the S3-Check system. In addition, the influence of shoulder pain intensity and BMI on the outcome parameters was analysed. Results Patients with shoulder pain showed significantly worse results in measurements of postural stability right/left (p < 0.01) and front/back (p < 0.01) as well as balance ability right/left (p = 0.01) and front/back (p < 0.01) compared to healthy controls. There were no significant group differences with regard to symmetry index. However, there was a significant (p < 0.01) symmetry shift towards the affected side within the shoulder pain group. There was no correlation between pain intensity and measurements of balance ability or postural stability. Likewise, no correlation between BMI and deficiencies in balance ability and postural stability was established. Conclusions Patients with pathological shoulder pain (> 4 months) have deficiencies in balance ability and postural stability; however the underlying mechanisms for this remain unclear. Neither pain intensity nor BMI influenced the outcome parameters. Patients with shoulder pain shift their weight to the affected side. Further research is needed to determine if balance training can improve rehabilitation results in patients with shoulder pathologies. PMID:24088342

The effect of leg preference on postural stability in healthy athletes.

PubMed

Huurnink, Arnold; Fransz, Duncan P; Kingma, Idsart; Hupperets, Maarten D W; van Dieën, Jaap H

2014-01-03

In research regarding postural stability, leg preference is often tested and controlled for. However, leg preference may vary between tasks. As athletes are a group of interest for postural stability testing, we evaluated the effect of five leg preference tasks categorization (step up, hop, ball kick, balance, pick up) on single-leg postural stability of 16 field hockey athletes. The 'center of pressure speed' was calculated as the primary outcome variable of single-leg postural stability. Secondary variables were 'mean length of the GRF vector in the horizontal plane', 'mean length of the ankle angular velocity vector', and 'mean length of the hip angular velocity vector', as well as the separate outcomes per degree of freedom. Results showed that leg preference was inconsistent between leg preference tasks. Moreover, the primary and secondary variables yielded no significant difference between the preferred and non-preferred legs, regardless of the applied leg preference task categorization (p>0.05). The present findings do not support the usability of leg preference tasks in controlling for bias of postural stability. In conclusion, none of the applied leg preference tasks revealed a significant effect on postural stability in healthy field hockey athletes. © 2013 Published by Elsevier Ltd.

Three-dimensional evaluation of postural stability in Parkinson's disease with mobile technology.

PubMed

Ozinga, Sarah J; Koop, Mandy Miller; Linder, Susan M; Machado, Andre G; Dey, Tanujit; Alberts, Jay L

2017-01-01

Postural instability is a hallmark of Parkinson's disease. Objective metrics to characterize postural stability are necessary for the development of treatment algorithms to aid in the clinical setting. The aim of this project was to validate a mobile device platform and resultant three-dimensional balance metric that characterizes postural stability. A mobile Application was developed, in which biomechanical data from inertial sensors within a mobile device were processed to characterize movement of center of mass in the medial-lateral, anterior-posterior and trunk rotation directions. Twenty-seven individuals with Parkinson's disease and 27 age-matched controls completed various balance tasks. A postural stability metric quantifying the amplitude (peak-to-peak) of sway acceleration in each movement direction was compared between groups. The peak-to-peak value in each direction for each individual with Parkinson's disease across all trials was expressed as a normalized value of the control data to identify individuals with severe postural instability, termed Cleveland Clinic-Postural Stability Index. In all conditions, the balance metric for peak-to-peak was significantly greater in Parkinson's disease compared to controls (p < 0.01 for all tests). The balance metric, in conjunction with mobile device sensors, provides a rapid and systematic metric for quantifying postural stability in Parkinson's disease.

Postural strategies in Prader-Willi and Down syndrome patients.

PubMed

Cimolin, Veronica; Galli, Manuela; Grugni, Graziano; Vismara, Luca; Precilios, Helmer; Albertini, Giorgio; Rigoldi, Chiara; Capodaglio, Paolo

2011-01-01

Patients affected by Down (DS) and Prader-Willi syndrome (PWS) are characterised by some common clinical and functional features including gait disorders and reduced postural control. The aim of our study was to quantitatively compare postural control in adult PWS and DS. We studied 12 PWS and 19 DS adult patients matched for age, height, weight and body mass index. They were instructed to maintain an upright standing position on a force platform for 30s with open eyes (OE) and we calculated the range of center of pressure (CoP) displacement in the A/P direction (RANGE(AP)) and in the M/L direction (RANGE(ML)) and the total CoP trajectory length during quiet stance (Sway Path, SP). The range of oscillations in PWS and DS in both AP and ML direction were higher than in controls. PWS and DS were statistically different for RANGE(AP), with PWS showing higher mean values. Our results confirm a reduced capacity of both PWS and DS in maintaining postural stability. This appears to be in some respect different in PWS and DS, with PWS showing poorer control in AP. DS and, particularly, PWS should be encouraged to undergo specific balance training and strengthening of the ankle muscles as part of a comprehensive rehabilitation program to enhance daily functioning and quality of life. Copyright © 2010 Elsevier Ltd. All rights reserved.

Effects of Changing Body Weight Distribution on Mediolateral Stability Control during Gait Initiation

PubMed Central

Caderby, Teddy; Yiou, Eric; Peyrot, Nicolas; de Viviés, Xavier; Bonazzi, Bruno; Dalleau, Georges

2017-01-01

During gait initiation, anticipatory postural adjustments (APA) precede the execution of the first step. It is generally acknowledged that these APA contribute to forward progression but also serve to stabilize the whole body in the mediolateral direction during step execution. Although previous studies have shown that changes in the distribution of body weight between both legs influence motor performance during gait initiation, it is not known whether and how such changes affect a person’s postural stability during this task. The aim of this study was to investigate the effects of changing initial body weight distribution between legs on mediolateral postural stability during gait initiation. Changes in body weight distribution were induced under experimental conditions by modifying the frontal plane distribution of an external load located at the participants’ waists. Fifteen healthy adults performed a gait initiation series at a similar speed under three conditions: with the overload evenly distributed over both legs; with the overload strictly distributed over the swing-limb side; and with the overload strictly distributed over the stance-leg side. Our results showed that the mediolateral location of center-of-mass (CoM) during the initial upright posture differed between the experimental conditions, indicating modifications in the initial distribution of body weight between the legs according to the load distribution. While the parameters related to the forward progression remained unchanged, the alterations in body weight distribution elicited adaptive changes in the amplitude of APA in the mediolateral direction (i.e., maximal mediolateral shift of the center of pressure (CoP)), without variation in their duration. Specifically, it was observed that the amplitude of APA was modulated in such a way that mediolateral dynamic stability at swing foot-contact, quantified by the margin of stability (i.e., the distance between the base of support boundary and the extrapolated CoM position), did not vary between the conditions. These findings suggest that APA seem to be scaled as a function of the initial body weight distribution between both legs so as to maintain optimal conditions of stability during gait initiation. PMID:28396629

Preliminary results of dancing exercise on postural stability in adolescent females.

PubMed

Cheng, Hsu-Sheng; Law, Cheung-Lun; Pan, Hui-Fang; Hsiao, Yueh-Ping; Hu, Jeng-Ho; Chuang, Fu-Kai; Huang, Mao-Hsiung

2011-12-01

Twenty-six female student dancers of Chung-hua school of Art (mean age 17.5 ± 0.5 years) and twenty-five healthy active female collegiate students (mean age 18.1 ± 1.0 years) participated in this study to investigate the effects of dancing exercise on postural stability of adolescent female through a comparison study of two cohorts. The groups were matched in height and weight. Participants were excluded for left-side dominance, sustained lower extremity injury, any known vestibular system dysfunction, uncorrected visual problems, and other neurological conditions. Static and dynamic standing balances were measured by means of Biodex Stability System in six conditions include bilateral, dominant, and nondominant single leg stances with eye-open and eye-closed conditions. To investigate the difference between static and dynamic stabilities, two protocols were performed: the first protocol consisted of four positions including static position, Level 8, Level 4, and Level 1, respectively. They were instructed to maintain a level platform as stably as possible for a period of 30 seconds for each test and given a 30-second rest between tests. The second protocol was descending stability level that was gradually changed from Level 12 to Level 1 for 60 seconds. Balance indices included overall stability index, anterior-posterior stability index (APSI), and medial-lateral stability index. The results of first protocol showed that there were significant differences in overall stability index score between study and control groups at Level 8 with dominant single leg standing in the eye-open condition and the APSI score at Level 8 and at Level 4 with dominant single-leg standing in the eye-closed condition. There was no significant difference in the second protocol. The possible explanation is loss of familiarization adaptation because of level change consequently in both the groups, not step-by-step as in the first protocol study. Furthermore, a positive correlation was found between the dancing experience and the APSI at Level 8 and Level 4 with dominant single-leg standing in the eye-closed condition. In conclusion the findings implied that dancing exercise results in better postural stability and less visual dependence on postural control in adolescent females. Copyright © 2011. Published by Elsevier B.V.

Determining postural stability

NASA Technical Reports Server (NTRS)

Forth, Katharine E. (Inventor); Paloski, William H. (Inventor); Lieberman, Erez (Inventor)

2011-01-01

A method for determining postural stability of a person can include acquiring a plurality of pressure data points over a period of time from at least one pressure sensor. The method can also include the step of identifying a postural state for each pressure data point to generate a plurality of postural states. The method can include the step of determining a postural state of the person at a point in time based on at least the plurality of postural states.

Investigating the anticipatory postural adjustment phase of gait initiation in different directions in chronic ankle instability patients.

PubMed

Ebrahimabadi, Zahra; Naimi, Sedigheh Sadat; Rahimi, Abbas; Sadeghi, Heydar; Hosseini, Seyed Majid; Baghban, Alireza Akbarzadeh; Arslan, Syed Asadullah

2018-01-01

The main objective of the present study was to analyze how supra spinal motor control mechanisms are altered in different directions during anticipatory postural phase of gait initiation in chronic ankle instability patients. It seems that supra spinal pathways modulate anticipatory postural adjustment phase of gait initiation. Yet, there is a dearth of research on the effect of chronic ankle instability on the anticipatory postural adjustment phase of gait initiation in different directions. A total of 20 chronic ankle instability participants and 20 healthy individuals initiated gait on a force plate in forward, 30° lateral, and 30° medial directions. According to the results of the present study, the peak lateral center of pressure shift decreased in forward direction compared to that in other directions in both groups. Also, it was found that the peak lateral center of pressure shift and the vertical center of mass velocity decreased significantly in chronic ankle instability patients, as compared with those of the healthy individuals. According to the results of the present study, it seems that chronic ankle instability patients modulate the anticipatory postural adjustment phase of gait initiation, compared with healthy control group, in order to maintain postural stability. These changes were observed in different directions, too. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of textured foot orthotics on static and dynamic postural stability in middle-aged females.

PubMed

Wilson, Marjorie L; Rome, Keith; Hodgson, David; Ball, Peter

2008-01-01

Foot orthotics (FO) may be prescribed for a range of lower limb and foot conditions. Prior studies report use of FO in enhancing postural stability in healthy younger adults, and do not control for footwear type. Currently, interest in the effects of FO on postural stability in older adults has increased. Limited reports exist of the effects on postural stability of FO made of combinations of materials, thicknesses and surface textures. In this study 40 healthy females (51.1+/-5.8 years) recruited into a within subject test-retest randomised clinical trial were provided with identical footwear and randomised into four FO conditions (control, grid, dimple and plain, n=10 for each condition). Participants wore the footwear for 4 weeks, a minimum of 6h/day. A Kistler force plate was used to determine postural stability variables (anterior-posterior displacements and medial-lateral displacements) for each participant in a static position, with eyes open and eyes closed. Base of support was evaluated using the GAITRite system. Each outcome measure was measured at baseline and 4 weeks. Postural stability variables demonstrated no significant differences between the four FO conditions. No significant differences were observed with base of support between the four conditions. We have demonstrated no detrimental effects on postural stability in older females after 4 weeks. This is regardless of orthotic texture and is independent of footwear. Biomechanical or sensory effects of FO on postural stability are still to be determined. These may be dependent on the geometry and texture of the orthotic.

Independent walking as a major skill for the development of anticipatory postural control: evidence from adjustments to predictable perturbations.

PubMed

Cignetti, Fabien; Zedka, Milan; Vaugoyeau, Marianne; Assaiante, Christine

2013-01-01

Although there is suggestive evidence that a link exists between independent walking and the ability to establish anticipatory strategy to stabilize posture, the extent to which this skill facilitates the development of anticipatory postural control remains largely unknown. Here, we examined the role of independent walking on the infants' ability to anticipate predictable external perturbations. Non-walking infants, walking infants and adults were sitting on a platform that produced continuous rotation in the frontal plane. Surface electromyography (EMG) of neck and lower back muscles and the positions of markers located on the platform, the upper body and the head were recorded. Results from cross-correlation analysis between rectified and filtered EMGs and platform movement indicated that although muscle activation already occurred before platform movement in non-walking infants, only walking infants demonstrated an adult-like ability for anticipation. Moreover, results from further cross-correlation analysis between segmental angular displacement and platform movement together with measures of balance control at the end-points of rotation of the platform evidenced two sorts of behaviour. The adults behaved as a non-rigid non-inverted pendulum, rather stabilizing head in space, while both the walking and non-walking infants followed the platform, behaving as a rigid inverted pendulum. These results suggest that the acquisition of independent walking plays a role in the development of anticipatory postural control, likely improving the internal model for the sensorimotor control of posture. However, despite such improvement, integrating the dynamics of an external object, here the platform, within the model to maintain balance still remains challenging in infants.

Modelling Human Performance in Maritime Interdiction Operations

DTIC Science & Technology

2010-10-01

tire relatively quickly compared to the legs. However, the arms and legs may be fatigued from the HSC insertion phase where muscular work will be...MI personnel include: • HSC Coxswain • Insertion/On-Target/Exfiltration phases – coping with Repeated Shock (RS), ( eccentric muscle contractions...and maintaining postural stability (isometric muscle contractions). • Boarding Team • Insertion – coping with RS ( eccentric muscle contractions), and

Postural stability and vehicle kinematics during an evasive lane change manoeuvre: a driver training study.

PubMed

Petersen, Andrew; Barrett, Rod

2009-05-01

The purpose of this study was to investigate the effect of a 2-day driver-training course that emphasised postural stability maintenance during critical driving situations on postural stability and vehicle kinematics during an evasive lane change manoeuvre. Following training, the trainee group experienced enhanced postural stability during specific phases of the task. In terms of vehicle kinematics, the main adaptation to training was that trained drivers reduced the extent to which they experienced vehicle decelerations during rapid turning compared to controls. Such a strategy may confer a safety benefit due to the increased risks associated with simultaneous braking while turning during an evasive manoeuvre. The newly learned strategy was consistent with the strategy used by a group of highly skilled drivers (driving instructors). Taken together, the results of the study suggest postural stability may be a useful variable to consider in relation to the skill-based component of hierarchical driver training programmes. The findings of this study provide some preliminary evidence to suggest that postural stability may be an important consideration when instructing individuals on how to safely negotiate obstacles during driving.

Emergence of postural patterns as a function of vision and translation frequency

NASA Technical Reports Server (NTRS)

Buchanan, J. J.; Horak, F. B.; Peterson, B. W. (Principal Investigator)

1999-01-01

Emergence of postural patterns as a function of vision and translation frequency. We examined the frequency characteristics of human postural coordination and the role of visual information in this coordination. Eight healthy adults maintained balance in stance during sinusoidal support surface translations (12 cm peak to peak) in the anterior-posterior direction at six different frequencies. Changes in kinematic and dynamic measures revealed that both sensory and biomechanical constraints limit postural coordination patterns as a function of translation frequency. At slow frequencies (0.1 and 0.25 Hz), subjects ride the platform (with the eyes open or closed). For fast frequencies (1.0 and 1.25 Hz) with the eyes open, subjects fix their head and upper trunk in space. With the eyes closed, large-amplitude, slow-sway motion of the head and trunk occurred for fast frequencies above 0.5 Hz. Visual information stabilized posture by reducing the variability of the head's position in space and the position of the center of mass (CoM) within the support surface defined by the feet for all but the slowest translation frequencies. When subjects rode the platform, there was little oscillatory joint motion, with muscle activity limited mostly to the ankles. To support the head fixed in space and slow-sway postural patterns, subjects produced stable interjoint hip and ankle joint coordination patterns. This increase in joint motion of the lower body dissipated the energy input by fast translation frequencies and facilitated the control of upper body motion. CoM amplitude decreased with increasing translation frequency, whereas the center of pressure amplitude increased with increasing translation frequency. Our results suggest that visual information was important to maintaining a fixed position of the head and trunk in space, whereas proprioceptive information was sufficient to produce stable coordinative patterns between the support surface and legs. The CNS organizes postural patterns in this balance task as a function of available sensory information, biomechanical constraints, and translation frequency.

A Simple Postflight Measure of Postural Atania in Astronauts

NASA Technical Reports Server (NTRS)

Reschke, M. F.; Harm, D. I.; Kofman, I. S.; Wood, S. J.; Bloomberg, J. J.

2011-01-01

Astronauts returning from space flight universally present with postural ataxia. Throughout the Space Shuttle Program, measurement of ataxia has concentrated on sway in the anterior-posterior (AP) plane. The current investigation, as a part of a larger functional study, concentrated on characterizing postural instability using dynamic stabilographic sway patterns in both the AP and medial-lateral (ML) planes. To accomplish this goal, six astronauts from short-duration (Shuttle) and three from long-duration (ISS) flights were required to recover from a simulated fall. Subjects with eyes open, wearing running shoes lay prone on the floor for 2 minutes and then quickly stood up, maintained a quiet stance for 3 minutes, arms relaxed along the side of the body, and feet comfortably placed on the force plate. Crewmembers were tested twice before flight, on landing day (Shuttle only), and 1, 6, and 30 days after flight. Anterior-posterior and ML center-of-pressure (COP) coordinates were calculated from the ground reaction forces collected at 500 Hz. The 3-minute quiet stance trial was broken into three 1-minute segments for stabilogram diffusion analysis. A mean sway speed (rate of change of COP displacement) was also calculated as an additional postural stability parameter. While there was considerable variation, most of crewmembers tested exhibited increased stochastic activity evidenced by larger short-term COP diffusion coefficients postflight in both the AP and ML planes, suggesting significant changes in postural control mechanisms, particularly control of lower limb muscle function. As expected, postural instability of ISS astronauts on the first day postflight was similar to that of Shuttle crewmembers on landing day. Recoveries of stochastic activity and mean sway speed to baseline levels were typically observed by the 30th day postflight for both long-duration and short-duration crewmembers. Dynamic postural stability characteristics obtained in this low-impact study complement the data measured with computerized dynamic posturography.

Postural Stability in Cigarette Smokers and During Abstinence from Alcohol

PubMed Central

Schmidt, Thomas Paul; Pennington, David Louis; Durazzo, Timothy Craig; Meyerhoff, Dieter Johannes

2014-01-01

Background Static postural instability is common in alcohol dependent individuals (ALC). Chronic alcohol consumption has deleterious effects on the neural and perceptual systems subserving postural stability. However, little is known about the effects of chronic cigarette smoking on postural stability and its changes during abstinence from alcohol. Methods A modified Fregly ataxia battery was administered to a total of 115 smoking (sALC) and non-smoking ALC (nsALC) and to 74 smoking (sCON) and non-smoking light/non-drinking controls (nsCON). Subgroups of abstinent ALC were assessed at 3 time points (approximately 1 week, 5 weeks, 34 weeks of abstinence from alcohol); a subset of nsCON was re-tested at 40 weeks. We tested if cigarette smoking affects postural stability in CON and in ALC during extended abstinence from alcohol, and we used linear mixed effects modeling to measure change across time points within ALC. Results Chronic smoking was associated with reduced performance on the Sharpened Romberg eyes-closed task in abstinent ALC at all three time points and in CON. The test performance of nsALC increased significantly between 1 and 32 weeks of abstinence, whereas the corresponding increases for sALC between 1 and 35 weeks was non-significant. With long-term abstinence from alcohol, nsALC recovered into the range of nsCON and sALC recovered into the range of sCON. Static postural stability decreased with age and correlated with smoking variables but not with drinking measures. Conclusions Chronic smoking was associated with reduced static postural stability with eyes closed and with lower increases of postural stability during abstinence from alcohol. Smoking cessation in alcohol dependence treatment may facilitate recovery from static postural instability during abstinence. PMID:24721012

Postural stability in cigarette smokers and during abstinence from alcohol.

PubMed

Schmidt, Thomas P; Pennington, David L; Durazzo, Timothy C; Meyerhoff, Dieter J

2014-06-01

Static postural instability is common in alcohol-dependent individuals (ALC). Chronic alcohol consumption has deleterious effects on the neural and perceptual systems subserving postural stability. However, little is known about the effects of chronic cigarette smoking on postural stability and its changes during abstinence from alcohol. A modified Fregly ataxia battery was administered to a total of 115 smoking (sALC) and nonsmoking ALC (nsALC) and to 71 smoking (sCON) and nonsmoking light/nondrinking controls (nsCON). Subgroups of abstinent ALC were assessed at 3 time points (TPs; approximately 1, 5, 34 weeks of abstinence from alcohol); a subset of nsCON was retested at 40 weeks. We tested whether cigarette smoking affects postural stability in CON and in ALC during extended abstinence from alcohol, and we used linear mixed effects modeling to measure change across TPs within ALC. Chronic smoking was associated with reduced performance on the Sharpened Romberg eyes-closed task in abstinent ALC at all 3 TPs and in CON. The test performance of nsALC increased significantly between 1 and 32 weeks of abstinence, whereas the corresponding increases for sALC between 1 and 35 weeks were nonsignificant. With long-term abstinence from alcohol, nsALC recovered into the range of nsCON and sALC recovered into the range of sCON. Static postural stability decreased with age and correlated with smoking variables but not with drinking measures. Chronic smoking was associated with reduced static postural stability with eyes closed and with lower increases of postural stability during abstinence from alcohol. Smoking cessation in alcohol dependence treatment may facilitate recovery from static postural instability during abstinence. Copyright © 2014 by the Research Society on Alcoholism.

Head Stability and Head-Trunk Coordination in Horseback Riders: The Contribution of Visual Information According to Expertise

PubMed Central

Olivier, Agnès; Faugloire, Elise; Lejeune, Laure; Biau, Sophie; Isableu, Brice

2017-01-01

Maintaining equilibrium while riding a horse is a challenging task that involves complex sensorimotor processes. We evaluated the relative contribution of visual information (static or dynamic) to horseback riders' postural stability (measured from the variability of segment position in space) and the coordination modes they adopted to regulate balance according to their level of expertise. Riders' perceptual typologies and their possible relation to postural stability were also assessed. Our main assumption was that the contribution of visual information to postural control would be reduced among expert riders in favor of vestibular and somesthetic reliance. Twelve Professional riders and 13 Club riders rode an equestrian simulator at a gallop under four visual conditions: (1) with the projection of a simulated scene reproducing what a rider sees in the real context of a ride in an outdoor arena, (2) under stroboscopic illumination, preventing access to dynamic visual cues, (3) in normal lighting but without the projected scene (i.e., without the visual consequences of displacement) and (4) with no visual cues. The variability of the position of the head, upper trunk and lower trunk was measured along the anteroposterior (AP), mediolateral (ML), and vertical (V) axes. We computed discrete relative phase to assess the coordination between pairs of segments in the anteroposterior axis. Visual field dependence-independence was evaluated using the Rod and Frame Test (RFT). The results showed that the Professional riders exhibited greater overall postural stability than the Club riders, revealed mainly in the AP axis. In particular, head variability was lower in the Professional riders than in the Club riders in visually altered conditions, suggesting a greater ability to use vestibular and somesthetic information according to task constraints with expertise. In accordance with this result, RFT perceptual scores revealed that the Professional riders were less dependent on the visual field than were the Club riders. Finally, the Professional riders exhibited specific coordination modes that, unlike the Club riders, departed from pure in-phase and anti-phase patterns and depended on visual conditions. The present findings provide evidence of major differences in the sensorimotor processes contributing to postural control with expertise in horseback riding. PMID:28194100

Stereotypy and Motor Control: Differences in the Postural Stability Dynamics of Persons with Stereotyped and Dyskinetic Movement Disorders.

ERIC Educational Resources Information Center

Bodfish, James W.; Parker, Dawn E.; Lewis, Mark H.; Sprague, Robert L.; Newell, Karl M.

2001-01-01

This study examined whether dynamic measures of postural stability differentiated stereotyped movement disorder from dyskinetic movement disorder in a severely mentally retarded population. Participants (N=20) with either stereotypy or dyskinesia movement disorders and a control group were given a goal-oriented postural stability task. Both groups…

The Role of Postural Support in Young Adults' Control of Stationary Kicking

ERIC Educational Resources Information Center

Sidaway, Ben; Bouchard, Matthew; Chasse, Julie; Dunn, Jonathan; Govoni, Andrea; McPherson, Breanne; Roy, Katherine; Anderson, David I.

2017-01-01

Purpose: The requirement for postural stability during the performance of motor skills has been clearly demonstrated in infants, but the necessity for such a postural substrate is not well documented in adults. The present study investigated the role of postural stability during a ballistic ball-kicking task in adults by providing varying degrees…

Light and heavy touch reduces postural sway and modifies axial tone in Parkinson’s disease

PubMed Central

Franzén, Erika; Paquette, Caroline; Gurfinkel, Victor; Horak, Fay

2014-01-01

Background Light touch with a stable object reduces postural sway by increasing axial postural tone in healthy subjects. However, it is unknown whether subjects with Parkinson’s disease (PD), who have more postural sway and higher axial postural tone than healthy subjects, can benefit from haptic touch. Objective To investigate the effect of light and heavy touch on postural stability and hip tone in subjects with PD. Methods Fourteen subjects with mid-stage PD, and 14 healthy control subjects were evaluated during quiet standing with eyes closed with their arms: 1) crossed, 2) lightly touching a fixed rigid bar in front of them and 3) firmly gripping the bar. Postural sway was measured with a forceplate and axial hip tone was quantified using a unique device that measures the resistance of the hips to yaw rotation while maintaining active stance. Results Subjects with PD significantly decreased their postural sway with light or heavy touch (p<0.001 vs. arms crossed), similarly as control subjects. Without touch, hip tone was larger in PD subjects. With touch, however, tone values were similar in both groups. This change in hip tone with touch was highly correlated with the initial amount of tone (PD: r=− 0.72 to −0.95 and controls: r=−0.74 to−0.85). Conclusions We showed, for the first time, that subjects with PD benefit from touch similarly to control subjects and that despite higher axial postural tone, PD subjects are able to modulate their tone with touch. Future studies should investigate the complex relationship between touch and postural tone. PMID:22415944

Postural Stability Assessment of University Marching Musicians Using Force Platform Measures.

PubMed

Magnotti, Trevor D; McElhiney, Danielle; Russell, Jeffrey A

2016-09-01

Lower extremity injury is prevalent in marching musicians, and poor postural stability is a possible risk factor for this. The external load of an instrument may predispose these performers to injury by decreasing postural stability. The purpose of this study was to determine the relationship between instrument load and static and dynamic postural stability in this population. Fourteen university marching musicians were recruited and completed a balance assessment protocol on a force platform with and without their instrument. Mean center of pressure (CoP) displacement was then calculated for each exercise in the anterior/posterior and medial/lateral planes. Mean anterior/posterior CoP displacement significantly increased in the instrument condition for the static surface, eyes closed, 2 feet condition (p≤0.005; d=0.89). No significant differences were found in the medial/lateral plane between non-instrument and instrument conditions. Significant differences were not found between test stance conditions independent of group. Comparisons between the non-instrument-loaded and instrument-loaded conditions revealed possible significance of instrument load on postural stability in the anterior/posterior plane. Mean differences indicated that an unstable surface created a greater destabilizing effect on postural stability than instrument load.

Postural Stability is Altered by Blood Shift

NASA Astrophysics Data System (ADS)

Marais, M.; Denise, P.; Guincetre, J. Y.; Normand, H.

2008-06-01

Non-vestibular influences as shift in blood volume changed perception of body posture. Then, factors affecting blood shift may alter postural control. The purpose of our study was to investigate the effects of leg venous contention on postural stability. Twelve subjects were studied on a balance plate for 5 minutes with the eyes closed, in 3 conditions: with no leg venous contention or grade 1 and 3 support stockings. Standard deviation of x and y position was calculated before and after the closure of the eyes. Strong venous contention altered postural stability, after the eyes were closed, during the first 10 s of standing. As support stockings prevent blood shift induced by upright posture, this result is in line with the hypothesis that blood shifts influence the perception of body orientation and postural control among others factors as vision, vestibular inputs... This strong venous contention could induce an increase of fall.

Ergonomics Contribution in Maintainability

NASA Astrophysics Data System (ADS)

Teymourian, Kiumars; Seneviratne, Dammika; Galar, Diego

2017-09-01

The objective of this paper is to describe an ergonomics contribution in maintainability. The economical designs, inputs and training helps to increase the maintainability indicators for industrial devices. This analysis can be helpful, among other cases, to compare systems, to achieve a better design regarding maintainability requirements, to improve this maintainability under specific industrial environment and to foresee maintainability problems due to eventual changes in a device operation conditions. With this purpose, this work first introduces the notion of ergonomics and human factors, maintainability and the implementation of assessment of human postures, including some important postures to perform maintenance activities. A simulation approach is used to identify the critical posture of the maintenance personnel and implements the defined postures with minimal loads on the personnel who use the equipment in a practical scenario. The simulation inputs are given to the designers to improve the workplace/equipment in order to high level of maintainability. Finally, the work concludes summarizing the more significant aspects and suggesting future research.

Understanding balance differences in individuals with multiple sclerosis with mild disability: An investigation of differences in sensory feedback on postural and dynamic balance control

NASA Astrophysics Data System (ADS)

Denomme, Luke T.

Multiple sclerosis (MS) is an autoimmune disease that affects the central nervous system (CNS) and causes a broad range of neurological symptoms. One of the most common symptoms experienced by individuals with MS is poor balance control during standing and walking. The main mechanism underlying impaired balance control in MS appears to result from slowed somatosensory conduction and impaired central integration. The current thesis assessed postural and dynamic control of balance of 'individuals with MS with mild disability' (IwMS). IwMS were compared to 'healthy age-matched individuals' (HAMI) and community-dwelling 'older adults' (OA). The purpose of this thesis was to quantify differences in postural and dynamic control of balance in IwMS to the two populations who display balance control differences across the lifespan and represent two extreme ends of the balance control continuum due to natural aging. IwMS (n = 12, x¯age: 44 +/- 9.4 years), HAMI (n = 12, x¯age: 45 +/- 9.9 years) and community-dwelling OA (n = 12, x¯ age: 68.1 +/- 4.5 years) postural and dynamic balance control were evaluated during a Romberg task as well as a dynamic steering task. The Romberg task required participants to stand with their feet together and hands by their sides for 45 seconds with either their eyes open or closed. The dynamic steering task required participants to walk and change direction along the M-L plane towards a visual goal. Results from these two tasks reveal that IwMS display differences in postural control when compared to HAMI when vision was removed as well as differences in dynamic stability margin during steering situations. During the postural control task IwMS displayed faster A-P and M-L COP velocities when vision was removed and their COP position was closer to their self-selected maximum stability limits compared to HAMI. Assessment of dynamic stability during the steering task revealed that IwMS displayed reduced walking speed and cadence during the straight walking portion of the task in addition to a smaller DSM range (i.e., COM remained close to lateral BOS) during the entire steering task. These results suggest that IwMS adopt postural and dynamic control strategies (i.e., increased COP velocity, smaller self-selected maximal sway comfort zones and reduced walking speed) in order to maintain stability and complete the tasks. Results further revealed that IwMS display similar levels of postural and dynamic stability to OA despite differences in the type of sensory impairment possessed by each group. The findings also provide insights into the comparison of IwMS to two populations who represent the two extreme ends of the balance control continuum: HAMI and OA. Our data indicates that the level of postural and dynamic balance control in IwMS appears to express similar characteristics and may be located closer to the OA population on this continuum. Future research should evaluate the level of somatosensory impairment (i.e., monofilament testing and tuning fork tendon tap testing) between IwMS and OA in order to better differentiate levels of postural and dynamic balance control between groups and to gain a better understanding of where each group may be specifically located on the age-related balance control continuum.

Can we reduce the effort of maintaining a neutral sitting posture? A pilot study.

PubMed

O'Sullivan, Kieran; McCarthy, Raymond; White, Alison; O'Sullivan, Leonard; Dankaerts, Wim

2012-12-01

Neutral sitting postures encouraging lumbar lordosis have been recommended in the management of sitting-related low back pain (LBP). However, prolonged lordotic sitting postures can be associated with increased fatigue and discomfort. This pilot study investigated whether changing the type of chair used in sitting can reduce the effort of maintaining a neutral sitting posture. The muscle activation of six trunk muscles was recorded using surface electromyography in 12 painfree participants. Participants were facilitated into a neutral sitting posture for 1 min on both a standard backless office chair and a dynamic, forward-inclined chair (Back App). Lumbar multifidus activity was significantly lower on the Back App chair (p=0.013). None of the other five trunk muscles measured demonstrated a significant difference in activity between the chairs. There was no significant difference (p=0.108) in the perceived effort of maintaining the neutral sitting posture on the two chairs. This study suggests that the lumbar multifidus activation required to maintain a neutral sitting posture can be reduced by considering the type of chair used. The mechanism through which the Back App chair reduces lumbar multifidus activation is unclear, but the greatest difference between chairs is the degree of hip flexion. The ability to maintain a neutral lumbar posture with less lumbar multifidus activation is potentially advantageous during prolonged sitting. Further investigations of the effects of chair design on longer duration sitting, and among LBP subjects, are warranted. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of dual tasks and dual-task training on postural stability: a systematic review and meta-analysis

PubMed Central

Ghai, Shashank; Ghai, Ishan; Effenberg, Alfred O

2017-01-01

The use of dual-task training paradigm to enhance postural stability in patients with balance impairments is an emerging area of interest. The differential effects of dual tasks and dual-task training on postural stability still remain unclear. A systematic review and meta-analysis were conducted to analyze the effects of dual task and training application on static and dynamic postural stability among various population groups. Systematic identification of published literature was performed adhering to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, from inception until June 2016, on the online databases Scopus, PEDro, MEDLINE, EMBASE, and SportDiscus. Experimental studies analyzing the effects of dual task and dual-task training on postural stability were extracted, critically appraised using PEDro scale, and then summarized according to modified PEDro level of evidence. Of 1,284 records, 42 studies involving 1,480 participants met the review’s inclusion criteria. Of the studies evaluating the effects of dual-task training on postural stability, 87.5% of the studies reported significant enhancements, whereas 30% of the studies evaluating acute effects of dual tasks on posture reported significant enhancements, 50% reported significant decrements, and 20% reported no effects. Meta-analysis of the pooled studies revealed moderate but significant enhancements of dual-task training in elderly participants (95% CI: 1.16–2.10) and in patients suffering from chronic stroke (−0.22 to 0.86). The adverse effects of complexity of dual tasks on postural stability were also revealed among patients with multiple sclerosis (−0.74 to 0.05). The review also discusses the significance of verbalization in a dual-task setting for increasing cognitive–motor interference. Clinical implications are discussed with respect to practical applications in rehabilitation settings. PMID:28356727

Effects of dual tasks and dual-task training on postural stability: a systematic review and meta-analysis.

PubMed

Ghai, Shashank; Ghai, Ishan; Effenberg, Alfred O

2017-01-01

The use of dual-task training paradigm to enhance postural stability in patients with balance impairments is an emerging area of interest. The differential effects of dual tasks and dual-task training on postural stability still remain unclear. A systematic review and meta-analysis were conducted to analyze the effects of dual task and training application on static and dynamic postural stability among various population groups. Systematic identification of published literature was performed adhering to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, from inception until June 2016, on the online databases Scopus, PEDro, MEDLINE, EMBASE, and SportDiscus. Experimental studies analyzing the effects of dual task and dual-task training on postural stability were extracted, critically appraised using PEDro scale, and then summarized according to modified PEDro level of evidence. Of 1,284 records, 42 studies involving 1,480 participants met the review's inclusion criteria. Of the studies evaluating the effects of dual-task training on postural stability, 87.5% of the studies reported significant enhancements, whereas 30% of the studies evaluating acute effects of dual tasks on posture reported significant enhancements, 50% reported significant decrements, and 20% reported no effects. Meta-analysis of the pooled studies revealed moderate but significant enhancements of dual-task training in elderly participants (95% CI: 1.16-2.10) and in patients suffering from chronic stroke (-0.22 to 0.86). The adverse effects of complexity of dual tasks on postural stability were also revealed among patients with multiple sclerosis (-0.74 to 0.05). The review also discusses the significance of verbalization in a dual-task setting for increasing cognitive-motor interference. Clinical implications are discussed with respect to practical applications in rehabilitation settings.

Skeletal Muscle Pump Drives Control of Cardiovascular and Postural Systems

NASA Astrophysics Data System (ADS)

Verma, Ajay K.; Garg, Amanmeet; Xu, Da; Bruner, Michelle; Fazel-Rezai, Reza; Blaber, Andrew P.; Tavakolian, Kouhyar

2017-03-01

The causal interaction between cardio-postural-musculoskeletal systems is critical in maintaining postural stability under orthostatic challenge. The absence or reduction of such interactions could lead to fainting and falls often experienced by elderly individuals. The causal relationship between systolic blood pressure (SBP), calf electromyography (EMG), and resultant center of pressure (COPr) can quantify the behavior of cardio-postural control loop. Convergent cross mapping (CCM) is a non-linear approach to establish causality, thus, expected to decipher nonlinear causal cardio-postural-musculoskeletal interactions. Data were acquired simultaneously from young participants (25 ± 2 years, n = 18) during a 10-minute sit-to-stand test. In the young population, skeletal muscle pump was found to drive blood pressure control (EMG → SBP) as well as control the postural sway (EMG → COPr) through the significantly higher causal drive in the direction towards SBP and COPr. Furthermore, the effect of aging on muscle pump activation associated with blood pressure regulation was explored. Simultaneous EMG and SBP were acquired from elderly group (69 ± 4 years, n = 14). A significant (p = 0.002) decline in EMG → SBP causality was observed in the elderly group, compared to the young group. The results highlight the potential of causality to detect alteration in blood pressure regulation with age, thus, a potential clinical utility towards detection of fall proneness.

Postural stability effects of random vibration at the feet of construction workers in simulated elevation.

PubMed

Simeonov, P; Hsiao, H; Powers, J; Ammons, D; Kau, T; Amendola, A

2011-07-01

The risk of falls from height on a construction site increases under conditions which degrade workers' postural control. At elevation, workers depend heavily on sensory information from their feet to maintain balance. The study tested two hypotheses: "sensory enhancement"--sub-sensory (undetectable) random mechanical vibrations at the plantar surface of the feet can improve worker's balance at elevation; and "sensory suppression"--supra-sensory (detectable) random mechanical vibrations can have a degrading effect on balance in the same experimental settings. Six young (age 20-35) and six aging (age 45-60) construction workers were tested while standing in standard and semi-tandem postures on instrumented gel insoles. The insoles applied sub- or supra-sensory levels of random mechanical vibrations to the feet. The tests were conducted in a surround-screen virtual reality system, which simulated a narrow plank at elevation on a construction site. Upper body kinematics was assessed with a motion-measurement system. Postural stability effects were evaluated by conventional and statistical mechanics sway measures, as well as trunk angular displacement parameters. Analysis of variance did not confirm the "sensory enhancement" hypothesis, but provided evidence for the "sensory suppression" hypothesis. The supra-sensory vibration had a destabilizing effect, which was considerably stronger in the semi-tandem posture and affected most of the sway variables. Sensory suppression associated with elevated vibration levels on a construction site may increase the danger of losing balance. Construction workers at elevation, e.g., on a beam or narrow plank might be at increased risk of fall if they can detect vibrations under their feet. To reduce the possibility of losing balance, mechanical vibration to supporting structures used as walking/working surfaces should be minimized when performing construction tasks at elevation. Published by Elsevier Ltd.

A RCT comparing lumbosacral orthosis to routine physical therapy on postural stability in patients with chronic low back pain.

PubMed

Azadinia, Fatemeh; Ebrahimi-Takamjani, Ismail; Kamyab, Mojtaba; Parnianpour, Mohamad; Asgari, Morteza

2017-01-01

Background: Poor balance performance and impaired postural control have been frequently reported in patients with low back pain. However, postural control is rarely monitored during the course of treatment even though poor postural control may contribute to chronicity and recurrence of symptoms. Therefore, the present study aimed at investigating the effect of a nonextensible lumbosacral orthosis (LSO) versus routine physical therapy on postural stability of patients with nonspecific chronic low back pain. Methods: This was a randomized controlled trial conducted between November 2015 and May 2016 at the outpatient physical therapy clinic of the School of Rehabilitation Sciences. Patients with nonspecific chronic low back pain aged 20 to 55 years were randomly allocated to the intervention and control groups. Both groups received 8 sessions of physical therapy twice weekly for 4 weeks. The intervention group received nonextensible LSO in addition to routine physical therapy. Pain intensity, functional disability, fear of movement/ (re)injury, and postural stability in 3 levels of postural difficulty were measured before and after 4 weeks of intervention. A 2×2×3 mixed model of analysis of variance (ANOVA) was used to determine the main and interactive effects of the 3 factors including group, time, and postural difficulty conditions for each variable of postural stability. Results: The LSO and control groups displayed significant improvement in postural stability at the most difficult postural task conditions (P-value for 95% area ellipse was 0.003; and for phase plane, the mean total velocity and standard deviation of velocity was <0.001). Both groups exhibited a decrease in pain intensity, Oswestry Disability Index, and Tampa Scale of Kinesiophobia after 4 weeks of intervention. A significant difference between groups was found only for functional disability, with greater improvement in the orthosis group (t = 3.60, P<0.001). Conclusion: Both routine physical therapy and LSO significantly improved clinical and postural stability outcomes immediately after 4 weeks of intervention. The orthosis group did not display superior outcomes, except for functional disability.

A RCT comparing lumbosacral orthosis to routine physical therapy on postural stability in patients with chronic low back pain

PubMed Central

Azadinia, Fatemeh; Ebrahimi-Takamjani, Ismail; Kamyab, Mojtaba; Parnianpour, Mohamad; Asgari, Morteza

2017-01-01

Background: Poor balance performance and impaired postural control have been frequently reported in patients with low back pain. However, postural control is rarely monitored during the course of treatment even though poor postural control may contribute to chronicity and recurrence of symptoms. Therefore, the present study aimed at investigating the effect of a nonextensible lumbosacral orthosis (LSO) versus routine physical therapy on postural stability of patients with nonspecific chronic low back pain. Methods: This was a randomized controlled trial conducted between November 2015 and May 2016 at the outpatient physical therapy clinic of the School of Rehabilitation Sciences. Patients with nonspecific chronic low back pain aged 20 to 55 years were randomly allocated to the intervention and control groups. Both groups received 8 sessions of physical therapy twice weekly for 4 weeks. The intervention group received nonextensible LSO in addition to routine physical therapy. Pain intensity, functional disability, fear of movement/ (re)injury, and postural stability in 3 levels of postural difficulty were measured before and after 4 weeks of intervention. A 2×2×3 mixed model of analysis of variance (ANOVA) was used to determine the main and interactive effects of the 3 factors including group, time, and postural difficulty conditions for each variable of postural stability. Results: The LSO and control groups displayed significant improvement in postural stability at the most difficult postural task conditions (P-value for 95% area ellipse was 0.003; and for phase plane, the mean total velocity and standard deviation of velocity was <0.001). Both groups exhibited a decrease in pain intensity, Oswestry Disability Index, and Tampa Scale of Kinesiophobia after 4 weeks of intervention. A significant difference between groups was found only for functional disability, with greater improvement in the orthosis group (t = 3.60, P<0.001). Conclusion: Both routine physical therapy and LSO significantly improved clinical and postural stability outcomes immediately after 4 weeks of intervention. The orthosis group did not display superior outcomes, except for functional disability. PMID:29445655

Vestibular rehabilitation therapy: review of indications, mechanisms, and key exercises.

PubMed

Han, Byung In; Song, Hyun Seok; Kim, Ji Soo

2011-12-01

Vestibular rehabilitation therapy (VRT) is an exercise-based treatment program designed to promote vestibular adaptation and substitution. The goals of VRT are 1) to enhance gaze stability, 2) to enhance postural stability, 3) to improve vertigo, and 4) to improve activities of daily living. VRT facilitates vestibular recovery mechanisms: vestibular adaptation, substitution by the other eye-movement systems, substitution by vision, somatosensory cues, other postural strategies, and habituation. The key exercises for VRT are head-eye movements with various body postures and activities, and maintaining balance with a reduced support base with various orientations of the head and trunk, while performing various upper-extremity tasks, repeating the movements provoking vertigo, and exposing patients gradually to various sensory and motor environments. VRT is indicated for any stable but poorly compensated vestibular lesion, regardless of the patient's age, the cause, and symptom duration and intensity. Vestibular suppressants, visual and somatosensory deprivation, immobilization, old age, concurrent central lesions, and long recovery from symptoms, but there is no difference in the final outcome. As long as exercises are performed several times every day, even brief periods of exercise are sufficient to facilitate vestibular recovery. Here the authors review the mechanisms and the key exercises for each of the VRT goals.

Vestibular Rehabilitation Therapy: Review of Indications, Mechanisms, and Key Exercises

PubMed Central

Song, Hyun Seok; Kim, Ji Soo

2011-01-01

Vestibular rehabilitation therapy (VRT) is an exercise-based treatment program designed to promote vestibular adaptation and substitution. The goals of VRT are 1) to enhance gaze stability, 2) to enhance postural stability, 3) to improve vertigo, and 4) to improve activities of daily living. VRT facilitates vestibular recovery mechanisms: vestibular adaptation, substitution by the other eye-movement systems, substitution by vision, somatosensory cues, other postural strategies, and habituation. The key exercises for VRT are head-eye movements with various body postures and activities, and maintaining balance with a reduced support base with various orientations of the head and trunk, while performing various upper-extremity tasks, repeating the movements provoking vertigo, and exposing patients gradually to various sensory and motor environments. VRT is indicated for any stable but poorly compensated vestibular lesion, regardless of the patient's age, the cause, and symptom duration and intensity. Vestibular suppressants, visual and somatosensory deprivation, immobilization, old age, concurrent central lesions, and long recovery from symptoms, but there is no difference in the final outcome. As long as exercises are performed several times every day, even brief periods of exercise are sufficient to facilitate vestibular recovery. Here the authors review the mechanisms and the key exercises for each of the VRT goals. PMID:22259614

The effect of methylphenidate on postural stability under single and dual task conditions in children with attention deficit hyperactivity disorder - a double blind randomized control trial.

PubMed

Jacobi-Polishook, Talia; Shorer, Zamir; Melzer, Itshak

2009-05-15

To investigate the effects of Methylphenidate (MPH) on postural stability in attention deficit hyperactivity disorder (ADHD) children in single and dual task conditions. A randomized controlled double-blind study analyzing postural stability in 24 ADHD children before and after MPH vs. placebo treatments, in three task conditions: (1) Single task, standing still; (2) dual task, standing still performing a memory-attention demanding task; (3) standing still listening to music. MPH resulted in a significant improvement in postural stability during the dual task condition and while listening to music, with no equivalent improvement in placebo controls. MPH improves postural stability in ADHD, especially when an additional task is performed. This is probably due to enhanced attention abilities, thus contributing to improved balance control during performance of tasks that require attention. MPH remains to be studied as a potential drug treatment to improve balance control and physical functioning in other clinical populations.

Dynamic postural stability for double-leg drop landing.

PubMed

Niu, Wenxin; Zhang, Ming; Fan, Yubo; Zhao, Qinping

2013-01-01

Dynamic postural stability has been widely studied for single-leg landing, but seldom considered for double-leg landing. This study aimed to evaluate the dynamic postural stability and the influence mechanism of muscle activities during double-leg drop landing. Eight recreationally active males and eight recreationally active females participated in this study and dropped individually from three heights (0.32 m, 0.52 m, and 0.72 m). Ground reaction force was recorded to calculate the time to stabilisation. Electromyographic activities were recorded for selected lower-extremity muscles. A multivariate analysis of variance was carried out and no significant influence was found in time to stabilisation between genders or limb laterals (P > 0.05). With increasing drop height, time to stabilisation decreased significantly in two horizontal directions and the lower-extremity muscle activities were enhanced. Vertical time to stabilisation was not significantly influenced by drop height. Dynamic postural stability improved by neuromuscular change more than that required due to the increase of drop height. Double-leg landing on level ground is a stable movement, and the body would often be injured before dynamic postural stability is impaired. It is understandable to protect tissues from mechanical injuries by the sacrifice of certain dynamic postural stability in the design of protective devices or athlete training.

Immediate Beneficial Effects of Mental Rotation Using Foot Stimuli on Upright Postural Stability in Healthy Participants

PubMed Central

Kawasaki, Tsubasa

2013-01-01

The present study was designed to investigate whether an intervention during which participants were involved in mental rotation (MR) of a foot stimulus would have immediate beneficial effects on postural stability (Experiment 1) and to confirm whether it was the involvement of MR of the foot, rather than simply viewing foot stimuli, that could improve postural stability (Experiment 2). Two different groups of participants (n = 16 in each group) performed MR intervention of foot stimuli in each of the two experiments. Pre- and postmeasurements of postural stability during unipedal and bipedal standing were made using a force plate for the intervention. Consistently, postural sway values for unipedal standing, but not for bipedal standing, were decreased immediately after the MR intervention using the foot stimuli. Such beneficial effects were not observed after the MR intervention using car stimuli (Experiment 1) or when participants observed the same foot stimuli during a simple reaction task (Experiment 2). These findings suggest that the MR intervention using the foot stimuli could contribute to improving postural stability, at least when it was measured immediately after the intervention, under a challenging standing condition (i.e., unipedal standing). PMID:24459588

Control of movement initiation underlies the development of balance

PubMed Central

Ehrlich, David E.; Schoppik, David

2017-01-01

Summary Balance arises from the interplay of external forces acting on the body and internally generated movements. Many animal bodies are inherently unstable, necessitating corrective locomotion to maintain stability. Understanding how developing animals come to balance remains a challenge. Here we study the interplay between environment, sensation, and action as balance develops in larval zebrafish. We first model the physical forces that challenge underwater balance and experimentally confirm that larvae are subject to constant destabilization. Larvae propel in swim bouts that, we find, tend to stabilize the body. We confirm the relationship between locomotion and balance by changing larval body composition, exacerbating instability and eliciting more frequent swimming. Intriguingly, developing zebrafish come to control the initiation of locomotion, swimming preferentially when unstable, thus restoring preferred postures. To test the sufficiency of locomotor-driven stabilization and the developing control of movement timing, we incorporate both into a generative model of swimming. Simulated larvae recapitulate observed postures and movement timing across early development, but only when locomotor-driven stabilization and control of movement initiation are both utilized. We conclude the ability to move when unstable is the key developmental improvement to balance in larval zebrafish. Our work informs how emerging sensorimotor ability comes to impact how and why animals move when they do. PMID:28111151

Spatial Cues Provided by Sound Improve Postural Stabilization: Evidence of a Spatial Auditory Map?

PubMed Central

Gandemer, Lennie; Parseihian, Gaetan; Kronland-Martinet, Richard; Bourdin, Christophe

2017-01-01

It has long been suggested that sound plays a role in the postural control process. Few studies however have explored sound and posture interactions. The present paper focuses on the specific impact of audition on posture, seeking to determine the attributes of sound that may be useful for postural purposes. We investigated the postural sway of young, healthy blindfolded subjects in two experiments involving different static auditory environments. In the first experiment, we compared effect on sway in a simple environment built from three static sound sources in two different rooms: a normal vs. an anechoic room. In the second experiment, the same auditory environment was enriched in various ways, including the ambisonics synthesis of a immersive environment, and subjects stood on two different surfaces: a foam vs. a normal surface. The results of both experiments suggest that the spatial cues provided by sound can be used to improve postural stability. The richer the auditory environment, the better this stabilization. We interpret these results by invoking the “spatial hearing map” theory: listeners build their own mental representation of their surrounding environment, which provides them with spatial landmarks that help them to better stabilize. PMID:28694770

A model-based approach to stabilizing crutch supported paraplegic standing by artificial hip joint stiffness.

PubMed

van der Spek, Jaap H; Veltink, Peter H; Hermens, Hermie J; Koopman, Bart F J M; Boom, Herman B K

2003-12-01

The prerequisites for stable crutch supported standing were analyzed in this paper. For this purpose, a biomechanical model of crutch supported paraplegic stance was developed assuming the patient was standing with extended knees. When using crutches during stance, the crutches will put a position constraint on the shoulder, thus reducing the number of degrees of freedom. Additional hip-joint stiffness was applied to stabilize the hip joint and, therefore, to stabilize stance. The required hip-joint stiffness for changing crutch placement and hip-joint offset angle was studied under static and dynamic conditions. Modeling results indicate that, by using additional hip-joint stiffness, stable crutch supported paraplegic standing can be achieved, both under static as well as dynamic situations. The static equilibrium postures and the stability under perturbations were calculated to be dependent on crutch placement and stiffness applied. However, postures in which the hip joint was in extension (C postures) appeared to the most stable postures. Applying at least 60 N x m/rad hip-joint stiffness gave stable equilibrium postures in all cases. Choosing appropriate hip-joint offset angles, the static equilibrium postures changed to more erect postures, without causing instability or excessive arm forces to occur.

Recovery of postural equilibrium control following spaceflight

NASA Technical Reports Server (NTRS)

Paloski, W. H.; Reschke, M. F.; Black, F. O.; Doxey, D. D.; Harm, D. L.

1992-01-01

Decreased postural stability is observed in most astronauts immediately following spaceflight. Because ataxia may present postflight operational hazards, it is important to determine the incidence of postural instability immediately following landing and the dynamics of recovery of normal postural equilibrium control. It is postulated that postflight postural instability results from in-flight adaptive changes in central nervous system (CNS) processing of sensory information from the visual, vestibular, and proprioceptive systems. The purpose of the present investigation was to determine the magnitude and time course of postflight recovery of postural equilibrium control and, hence, readaptation of CNS processing of sensory information. Thirteen crew members from six spaceflight missions were studied pre- and postflight using a modified commercial posturography system. Postural equilibrium control was found to be seriously disrupted immediately following spaceflight in all subjects. Readaptation to the terrestrial environment began immediately upon landing, proceeded rapidly for the first 10-12 hours, and then proceeded much more slowly for the subsequent 2-4 days until preflight stability levels were reachieved. It is concluded that the overall postflight recovery of postural stability follows a predictable time course.

An 8-week thoracic spine stabilization exercise program improves postural back pain, spine alignment, postural sway, and core endurance in university students:a randomized controlled study.

PubMed

Toprak Çelenay, Şeyda; Özer Kaya, Derya

2017-04-18

To investigate the effects of an 8-week thoracic stabilization exercise program on back pain, spinal alignment, postural sway, and core endurance in university students. University students were randomly allocated into exercise (n: 28) and control (n: 25) groups. The exercise program was carried out 3 days a week for 8 weeks. Postural pain, spinal alignment, postural sway, and core endurance were assessed via visual analogue scale, Spinal Mouse, Biodex Balance System, and McGill's trunk muscle endurance tests at the baseline and after 8 weeks of training. Differences were observed for postural pain, thoracic and lumbar curvature, dynamic stability index (eyes closed), and core endurance scores in the exercise group between baseline and week 8 (P < 0.05) and all the parameters were significantly different when compared to those of the control group (P < 0.05). The program decreased postural pain, spinal curvatures, and postural sway, and increased core endurance in university students. The program can be effective in postural pain and misalignment of spine problems related to core weakness and balance disorders.

Postural stability in the elderly during sensory perturbations and dual tasking: the influence of refractive blur.

PubMed

Anand, Vijay; Buckley, John G; Scally, Andy; Elliott, David B

2003-07-01

To determine the influence of refractive blur on postural stability during somatosensory and vestibular system perturbation and dual tasking. Fifteen healthy, elderly subjects (mean age, 71 +/- 5 years), who had no history of falls and had normal vision, were recruited. Postural stability during standing was assessed using a force platform, and was determined as the root mean square (RMS) of the center of pressure (COP) signal in the anterior-posterior (A-P) and medial-lateral directions collected over a 30-second period. Data were collected under normal standing conditions and with somatosensory and vestibular system perturbations. Measurements were repeated with an additional physical and/or cognitive task. Postural stability was measured under conditions of binocular refractive blur of 0, 1, 2, 4, and 8 D and with eyes closed. The data were analyzed with a population-averaged linear model. The greatest increases in postural instability were due to disruptions of the somatosensory and vestibular systems. Increasing refractive blur caused increasing postural instability, and its effect was greater when the input from the other sensory systems was disrupted. Performing an additional cognitive and physical task increased A-P RMS COP further. All these detrimental effects on postural stability were cumulative. The findings highlight the multifactorial nature of postural stability and indicate why the elderly, many of whom have poor vision and musculoskeletal and central nervous system degeneration, are at greater risk of falling. The findings also highlight that standing instability in both normal and perturbed conditions was significantly increased with refractive blur. Correcting visual impairment caused by uncorrected refractive error could be a useful intervention strategy to help prevent falls and fall-related injuries in the elderly.

Design and Validation of a Low-Cost Portable Device to Quantify Postural Stability.

PubMed

Zhu, Yong

2017-03-18

Measurement of the displacement of the center-of-pressure (COP) is an important tool used in biomechanics to assess postural stability and human balance. The goal of this research was to design and validate a low-cost portable device that can offer a quick indication of the state of postural stability and human balance related conditions. Approximate entropy (ApEn) values reflecting the amount of irregularity hiding in COP oscillations were used to calculate the index. The prototype adopted a portable design using the measurements of the load cells located at the four corners of a low-cost force platform. The test subject was asked to stand on the device in a quiet, normal, upright stance for 30 s with eyes open and subsequently for 30 s with eyes closed. Based on the COP displacement signals, the ApEn values were calculated. The results indicated that the prototype device was capable of capturing the increase in regularity of postural control in the visual-deprivation conditions. It was also able to decipher the subtle postural control differences along anterior-posterior and medial-lateral directions. The data analysis demonstrated that the prototype would enable the quantification of postural stability and thus provide a low-cost portable device to assess many conditions related to postural stability and human balance such as aging and pathologies.

Predictors of Postural Stability in Children with ADHD

ERIC Educational Resources Information Center

Ghanizadeh, Ahmad

2011-01-01

Objective: As children with ADHD who have more inattention problems are more frequently with fine motor problems, it is not clear whether postural balance problems are associated with different subtypes of ADHD. This study investigates the predictors of postural stability in children with ADHD considering the covariant factors of age, gender, and…

Postural Stabilization Strategies to Motor Contagion Induced by Action Observation Are Impaired in Parkinson’s Disease

PubMed Central

Pelosin, Elisa; Bisio, Ambra; Pozzo, Thierry; Lagravinese, Giovanna; Crisafulli, Oscar; Marchese, Roberta; Abbruzzese, Giovanni; Avanzino, Laura

2018-01-01

Postural reactions can be influenced by concomitant tasks or different contexts and are modulated by a higher order motor control. Recent studies investigated postural changes determined by motor contagion induced by action observation (chameleon effect) showing that observing a model in postural disequilibrium induces an increase in healthy subjects’ body sway. Parkinson’s disease (PD) is associated with postural instability and impairments in cognitively controlled balance tasks. However, no studies investigated if viewing postural imbalance might influence postural stability in PD and if patients are able to inhibit a visual postural perturbation. In this study, an action observation paradigm for assessing postural reaction to motor contagion in PD subjects and healthy older adults was used. Postural stability changes were measured during the observation of a static stimulus (control condition) and during a point-light display of a gymnast balancing on a rope (biological stimulus). Our results showed that, during the observation of the biological stimulus, sway area and antero-posterior and medio-lateral displacements of center of pressure significantly increased only in PD participants, whereas correct stabilization reactions were present in elderly subjects. These results demonstrate that PD leads to a decreased capacity to control automatic imitative tendencies induced by motor contagion. This behavior could be the consequence either of an inability to inhibit automatic imitative tendencies or of the cognitive load requested by the task. Whatever the case, the issue about the ability to inhibit automatic imitative tendencies could be crucial for PD patients since it might increase falls risk and injuries. PMID:29545771

Tests of Dorsolateral Frontal Function Correlate with Objective Tests of Postural Stability in Early to Moderate Stage Parkinson’s Disease

PubMed Central

Nocera, Joe R.; Price, Catherine; Fernandez, Hubert H.; Amano, Shinichi; Vallabhajosula, Srikant; Okun, Michael S.; Hwynn, Nelson; Hass, Chris J.

2010-01-01

A substantial number of individuals with Parkinson’s disease who display impaired postural stability experience accelerated cognitive decline and an increased prevalence of dementia. To date, studies suggest that this relationship, believed to be due to involvement of nondopaminergic circuitry, occurs later in the disease process. Research has yet to adequately investigate this cognitive-posturomotor relationship especially when examining earlier disease states. To gain greater understanding of the relationship between postural stability and cognitive function/dysfunction we evaluated a more stringent, objective measure of postural stability (center of pressure displacement), and also more specific measures of cognition in twenty-two patients with early to moderate stage Parkinson’s disease. The magnitude of the center of pressure displacement in this cohort was negatively correlated with performance on tests known to activate dorsolateral frontal regions. Additionally, the postural stability item of the UPDRS exhibited poor correlation with the more objective measure of center of pressure displacement and all specific measures of cognition. These results may serve as rationale for a more thorough evaluation of postural stability and cognition especially in individuals with mild Parkinson’s disease. Greater understanding of the relationship between motor and cognitive processes in Parkinson’s disease will be critical for understanding the disease process and its potential therapeutic possibilities. PMID:20829093

Role of vestibular information in initiation of rapid postural responses

NASA Technical Reports Server (NTRS)

Runge, C. F.; Shupert, C. L.; Horak, F. B.; Zajac, F. E.; Peterson, B. W. (Principal Investigator)

1998-01-01

Patients with bilateral vestibular loss have difficulty maintaining balance without stepping when standing in tandem, on compliant surfaces, across narrow beams, or on one foot, especially with eyes closed. Normal individuals (with no sensory impairment) maintain balance in these tasks by employing quick, active hip rotation (a "hip strategy"). The absence of a hip strategy in vestibular patients responding to translations of a short support surface has previously been taken as evidence that the use of hip strategy requires an intact vestibular system. However, many tasks requiring hip strategy alter one or a combination of important system characteristics, such as initial state of the body (tandem stance), dynamics (compliant surfaces), or biomechanical limits of stability (narrow beams). Therefore, the balance deficit in these tasks may result from a failure to account for these support surface alterations when planning and executing sensorimotor responses. In this study, we tested the hypothesis that vestibular information is critical to trigger a hip strategy even on an unaltered support surface, which imposes no changes on the system characteristics. We recorded the postural responses of vestibular patients and control subjects with eyes closed to rearward support surface translations of varying velocity, in erect stance on a firm, flat surface. Subjects were instructed to maintain balance without stepping, if possible. Faster translation velocities (25 cm/s or more) produced a consistent pattern of early hip torque (first 400 ms) in control subjects (i.e., a hip strategy). Most of the patients with bilateral vestibular loss responded to the same translation velocities with similar torques. Contrary to our hypothesis, we conclude that vestibular function is not necessary to trigger a hip strategy. We postulate, therefore, that the balance deficit previously observed in vestibular patients during postural tasks that elicit a hip strategy may have been due to the sensorimotor consequences of the system alterations imposed by the postural tasks used in those studies. Preliminary results from two younger patients who lost vestibular function as infants indicate that age, duration of vestibular loss, and/or the timing of the loss may also be factors that can influence the use of hip strategy as a rapid postural response.

The involvement of musculoskeletal system and its influence on postural stability in children and young adults with cystic fibrosis.

PubMed

Kenis-Coskun, Ozge; Karadag-Saygi, Evrim; Bahar-Ozdemir, Yeliz; Gokdemir, Yasemin; Karadag, Bulent; Kayhan, Onder

2017-11-21

Cystic fibrosis (CF) affects the musculoskeletal system via a multifactorial pathway that includes vitamin D deficiency and involvement of respiratory muscles such as intercostals due to recurrent upper and lower respiratory tract infections. Eventual result is the deterioration of musculoskeletal health and posture in CF patients. Postural stability is directly affected by posture and can be compromised in every musculoskeletal problem. The aim of this study is to evaluate musculoskeletal system and postural stability in patients with CF. Patients with CF over six years of age and age and sex-matched control groups were included in the study. Cobb angle and thoracic kyphosis angles were measured on the spine radiographs. Both patients and control group were examined with pediatric gait, arms, legs and spine scale (pGALS). They also were evaluated with a NeuroCom Balance Master for their postural stability. Fifty-one patients with CF and 94 healthy controls participated in the study. In results of the pGALS examination, CF group had significantly more pathological findings than the control group in lower extremity appearance and movement (p = 0.006 and p = 0.01) and spine appearance and movement (p = 0.001 and p = 0.022) domains. The tandem walking speed was significantly higher in controls with a mean of 24.45 ± 7.79 while it was 20.47 ± 6.95 in the CF group (p = 0.03). Various limits of stability parameters also showed significant differences. Medium correlations were found between musculoskeletal examination and postural stability parameters. In patients with CF, a systematic but simple musculoskeletal examination can detect pathologies, which are more frequent than the normal population. These pathologies show a medium correlation with the involvement of postural stability.

INFLUENCE OF INJURY ON DYNAMIC POSTURAL CONTROL IN RUNNERS.

PubMed

Meardon, Stacey; Klusendorf, Anna; Kernozek, Thomas

2016-06-01

Injury has been linked with altered postural control in active populations. The association between running injury and dynamic postural control has not been examined. The purpose of this study was to examine dynamic postural control in injured and uninjured runners using the Star Excursion Balance Test (SEBT), Time to Stabilization (TTS) of ground reaction forces following a single-leg landing, and postural stability indices reflecting the fluctuations in GRFs during single-leg landing and stabilization tasks (forward and lateral hop). It was hypothesized that dynamic postural control differences would exist between runners with a history of injury that interrupted training for ≥7 days (INJ) when compared to runners without injury (CON). Case-control study. Twenty-two INJ (14 F, 8 M; 23.7 ± 2.1 y; 22.3 ± 2.8 kg/m2; 29.5 ± 16.3 mi/wk) currently running > 50% pre-injury mileage without pain were compared with twenty-two matched CON (14F, 8M; 22.7 ± 1.2 y; 22.7 ± 2.7 kg/m2; 31.2 ± 19.6 mi/wk). INJ group was stratified by site of injury into two groups (Hip/Thigh/Knee and Lower Leg/Ankle/Foot) for secondary analysis. Leg length-normalized anterior, posterolateral, and posteromedial reach distances on the SEBT, medial/lateral and anterior/posterior ground reaction force TTS, directional postural stability indices, and a composite dynamic postural stability index (DPSI), were assessed using mixed model ANOVA (α=0.05) and effect sizes (d). No group X direction interaction or group differences were observed for the SEBT (p=0.51, 0.71) or TTS (p=0.83, 0.72) measures. A group X direction interaction was found for postural stability indices during the forward landing task (p<0.01). Both Hip/Thigh/Knee and Lower leg/Ankle/Foot INJ groups demonstrated a greater vertical postural stability index (VPSI) (p=0.01 for both, d=0.80, 0.95) and DPSI (p=0.01, 0.02, d=0.75, 0.93) when compared to CON suggesting impaired balance control. A group X direction interaction was also found for postural stability indices during the lateral landing task (p=0.03). Only the Hip/Thigh/Knee INJ runners displayed a greater VPSI (p=0.01, d=0.91) and DPSI (p=0.017, d=0.89) when compared to CON. When compared to CON, INJ runners demonstrated impaired dynamic control of vertical forces when performing the single leg landing and stabilization tasks. Clinicians should consider addressing dynamic control of vertical loads through functional tasks during the rehabilitation of running injury. Level 3.

Effects of orthopedic insoles on static balance of older adults wearing thick socks.

PubMed

Ma, Christina Zong-Hao; Wong, Duo Wai-Chi; Wan, Anson Hong-Ping; Lee, Winson Chiu-Chun

2018-06-01

The wearing of socks and insoles may affect the ability of the foot to detect tactile input influencing postural balance. The aim of this study was to investigate whether (1) thick socks adversely affected the elderly postural balance and (2) orthopedic insoles could improve the elderly postural balance while wearing thick socks. Repeated-measures study design. In total, 14 healthy older adults were recruited. A monofilament test was conducted to evaluate foot plantar sensation with and without thick socks. Subjects then performed the Romberg tests under three conditions: (1) barefoot, (2) with socks only, and (3) with both socks and insoles. Postural balance was assessed by measuring the center of pressure movement during standing in each experimental condition. Thick socks significantly decreased the monofilament score ( p < 0.001), suggesting reduction in ability to detect external forces. All center of pressure parameters increased significantly while wearing thick socks ( p < 0.017), implying reduction of postural stability. They then decreased significantly with the additional use of insoles ( p < 0.017). Previous studies have documented the changes in plantar pressure distribution with the use of orthopedic insoles. This study further suggests that such changes in contact mechanics could produce some balance-improving effects, which appears not to have been reported earlier. Clinical relevance Wearing thick socks reduces plantar pressure sensitivity and increases postural sway which may increase risk of falls. Orthopedic insoles and footwear with similar design could potentially be a cost-effective method in maintaining postural balance when wearing thick socks.

Role of different sensory inputs for maintenance of body posture in sitting rat and rabbit.

PubMed

Deliagina, T; Beloozerova, I N; Popova, L B; Sirota, M G; Swadlow, H A; Grant, G; Orlovsky, G N

2000-10-01

In this paper, we describe the postural activity in sitting rats and rabbits. An animal was positioned on the platform that could be tilted in the frontal plane for up to +/-20-30 degrees, and postural corrections were video recorded. We found that in both rat and rabbit, the postural reactions led to stabilization of the dorsal-side-up trunk orientation. The result of this was that the trunk tilt constituted only approximately 50% (rat) and 25% (rabbit) of the platform tilt. In addition, in the rabbit the head orientation was also stabilized. Trunk stabilization persisted in the animals subjected to the bilateral labyrinthectomy and blindfolding, suggesting that the somatosensory input is primarily responsible for trunk stabilization. Trunk stabilization was due to extension of the limbs on the side moving down, and flexion of the opposite limbs. EMG recordings showed that the limb extension was caused by the active contraction of extensor muscles. We argue that signals from the Golgi tendon organs of the extensor muscles may considerably contribute to elicitation of postural corrective responses to the lateral tilt.

Can vibratory feedback be used to improve postural stability in persons with transtibial limb loss?

PubMed

Rusaw, David; Hagberg, Kerstin; Nolan, Lee; Ramstrand, Nerrolyn

2012-01-01

The use of vibration as a feedback modality to convey motion of the body has been shown to improve measures of postural stability in some groups of patients. Because individuals using transtibial prostheses lack sensation distal to the amputation, vibratory feedback could possibly be used to improve their postural stability. The current investigation provided transtibial prosthesis users (n = 24, mean age 48 yr) with vibratory feedback proportional to the signal received from force transducers located under the prosthetic foot. Postural stability was evaluated by measuring center of pressure (CoP) movement, limits of stability, and rhythmic weight shift while participants stood on a force platform capable of rotations in the pitch plane (toes up/toes down). The results showed that the vibratory feedback increased the mediolateral displacement amplitude of CoP in standing balance and reduced the response time to rapid voluntary movements of the center of gravity. The results suggest that the use of vibratory feedback in an experimental setting leads to improvements in fast open-loop mechanisms of postural control in transtibial prosthesis users.

Dynamic Imbalance Analysis and Stability Control of Galloping Gait for a Passive Quadruped Robot.

PubMed

Wang, Chunlei; Zhang, Ting; Wei, Xiaohui; Long, Yongjun; Wang, Shigang

2015-01-01

Some imbalance and balance postures of a passive quadruped robot with a simplified mathematical model are studied. Through analyzing the influence of the touchdown angle of the rear leg on the posture of the trunk during the flight phase, the stability criterion is concluded: the closer are the two moments which are the zero time of the pitching angle and the peak time of the center of mass, the better is the stability of the trunk posture during the flight phase. Additionally, the validity of the stability criterion is verified for the cat, greyhound, lion, racehorse, basset hound, and giraffe. Furthermore, the stability criterion is also applicable when the center of the mass of body is shifted. Based on the stability criterion, the necessary and sufficient condition of the galloping stability for the quadruped robot is proposed to attain a controlled thrust. The control strategy is designed by an optimization dichotomy algorithm for seeking the zero point of the balance condition. Through the control results, it is demonstrated that the imbalance posture of the trunk could be stabilized by adjusting the stiffness of four legs.

Protecting Interests and Preventing War: An Analysis of PACAF Force Posture Alternatives

DTIC Science & Technology

2015-05-01

The overall goal was to maintain US leadership in the region and to ensure stability and economic prosperity. Nye claimed, “Our national interests...Kadena Air Base, Okinawa, was perfectly situated to influence events in Taiwan and the East China Sea, but its runways and other key facilities were...Army and Marine forces was extremely risky. America faced major power-projection problems in a key economic region, while China began a period of

Running over rough terrain reveals limb control for intrinsic stability.

PubMed

Daley, Monica A; Biewener, Andrew A

2006-10-17

Legged animals routinely negotiate rough, unpredictable terrain with agility and stability that outmatches any human-built machine. Yet, we know surprisingly little about how animals accomplish this. Current knowledge is largely limited to studies of steady movement. These studies have revealed fundamental mechanisms used by terrestrial animals for steady locomotion. However, it is unclear whether these models provide an appropriate framework for the neuromuscular and mechanical strategies used to achieve dynamic stability over rough terrain. Perturbation experiments shed light on this issue, revealing the interplay between mechanics and neuromuscular control. We measured limb mechanics of helmeted guinea fowl (Numida meleagris) running over an unexpected drop in terrain, comparing their response to predictions of the mass-spring running model. Adjustment of limb contact angle explains 80% of the variation in stance-phase limb loading following the perturbation. Surprisingly, although limb stiffness varies dramatically, it does not influence the response. This result agrees with a mass-spring model, although it differs from previous findings on humans running over surfaces of varying compliance. However, guinea fowl sometimes deviate from mass-spring dynamics through posture-dependent work performance of the limb, leading to substantial energy absorption following the perturbation. This posture-dependent actuation allows the animal to absorb energy and maintain desired velocity on a sudden substrate drop. Thus, posture-dependent work performance of the limb provides inherent velocity control over rough terrain. These findings highlight how simple mechanical models extend to unsteady conditions, providing fundamental insights into neuromuscular control of movement and the design of dynamically stable legged robots and prosthetic devices.

Outcomes of total hip arthroplasty: a study of patients one year postsurgery.

PubMed

Trudelle-Jackson, Elaine; Emerson, Roger; Smith, Sue

2002-06-01

Ex post facto research using prospective analysis of differences between the involved hip and uninvolved hip. To assess outcomes of total hip arthroplasty (THA) by comparing range of motion (ROM), muscle strength, and postural stability in the surgical hip to those of the uninvolved hip 1 year postsurgery. An additional objective was to assess degree of relationship among ROM, strength, and postural stability impairments to a measure of self-assessed function. Most patients who have THA receive physical therapy that consists mainly of self-care instructions and an exercise protocol that emphasizes mobility during the acute phase of recovery. But, outcomes of THA 1 year postsurgery indicate that current physical therapy programs used during the acute phase of recovery do not effectively restore physical and functional performance. Subjects consisted of 11 women and 4 men (mean age +/- standard deviation = 62 +/- 8 years) with unilateral THA performed 1 year prior to data collection. Assessment variables consisted of self-assessment of function and measures of postural stability, muscle strength, and hip ROM. The 12-Item Hip Questionnaire was used for self-assessment of function. Three separate repeated measures MANOVA were used to compare the involved side to the uninvolved side in measures of postural stability, strength, and ROM. The Spearman's rho was used to assess degree of association between the subjects' score of self-assessed function and impairments in strength and postural stability. Measures of postural stability were significantly lower (P < or = 0.01) on the side of the replaced hip. Differences in strength values between the involved and uninvolved sides were not statistically significant. Correlations between scores of self-assessed function and hip abductor and knee extensor strength were statistically significant (r = 0.56, P < or = 0.03). Self-assessed function was not significantly correlated to postural stability impairments. The brief postsurgical rehabilitation program received by patients with THA may not be sufficient. A second phase of rehabilitation implemented 4 months or more after surgery that emphasizes weight bearing and postural stability may be advisable.

Postural Control in Bilateral Vestibular Failure: Its Relation to Visual, Proprioceptive, Vestibular, and Cognitive Input.

PubMed

Sprenger, Andreas; Wojak, Jann F; Jandl, Nico M; Helmchen, Christoph

2017-01-01

Patients with bilateral vestibular failure (BVF) suffer from postural and gait unsteadiness with an increased risk of falls. The aim of this study was to elucidate the differential role of otolith, semicircular canal (SSC), visual, proprioceptive, and cognitive influences on the postural stability of BVF patients. Center-of-pressure displacements were recorded by posturography under six conditions: target visibility; tonic head positions in the pitch plane; horizontal head shaking; sensory deprivation; dual task; and tandem stance. Between-group analysis revealed larger postural sway in BVF patients on eye closure; but with the eyes open, BVF did not differ from healthy controls (HCs). Head tilts and horizontal head shaking increased sway but did not differ between groups. In the dual task condition, BVF patients maintained posture indistinguishable from controls. On foam and tandem stance, postural sway was larger in BVF, even with the eyes open. The best predictor for the severity of bilateral vestibulopathy was standing on foam with eyes closed. Postural control of our BVF was indistinguishable from HCs once visual and proprioceptive feedback is provided. This distinguishes them from patients with vestibulo-cerebellar disorders or functional dizziness. It confirms previous reports and explains that postural unsteadiness of BVF patients can be missed easily if not examined by conditions of visual and/or proprioceptive deprivation. In fact, the best predictor for vestibular hypofunction (VOR gain) was examining patients standing on foam with the eyes closed. Postural sway in that condition increased with the severity of vestibular impairment but not with disease duration. In the absence of visual control, impaired otolith input destabilizes BVF with head retroflexion. Stimulating deficient SSC does not distinguish patients from controls possibly reflecting a shift of intersensory weighing toward proprioceptive-guided postural control. Accordingly, proprioceptive deprivation heavily destabilizes BVF, even when visual control is provided.

Postural Control in Bilateral Vestibular Failure: Its Relation to Visual, Proprioceptive, Vestibular, and Cognitive Input

PubMed Central

Sprenger, Andreas; Wojak, Jann F.; Jandl, Nico M.; Helmchen, Christoph

2017-01-01

Patients with bilateral vestibular failure (BVF) suffer from postural and gait unsteadiness with an increased risk of falls. The aim of this study was to elucidate the differential role of otolith, semicircular canal (SSC), visual, proprioceptive, and cognitive influences on the postural stability of BVF patients. Center-of-pressure displacements were recorded by posturography under six conditions: target visibility; tonic head positions in the pitch plane; horizontal head shaking; sensory deprivation; dual task; and tandem stance. Between-group analysis revealed larger postural sway in BVF patients on eye closure; but with the eyes open, BVF did not differ from healthy controls (HCs). Head tilts and horizontal head shaking increased sway but did not differ between groups. In the dual task condition, BVF patients maintained posture indistinguishable from controls. On foam and tandem stance, postural sway was larger in BVF, even with the eyes open. The best predictor for the severity of bilateral vestibulopathy was standing on foam with eyes closed. Postural control of our BVF was indistinguishable from HCs once visual and proprioceptive feedback is provided. This distinguishes them from patients with vestibulo-cerebellar disorders or functional dizziness. It confirms previous reports and explains that postural unsteadiness of BVF patients can be missed easily if not examined by conditions of visual and/or proprioceptive deprivation. In fact, the best predictor for vestibular hypofunction (VOR gain) was examining patients standing on foam with the eyes closed. Postural sway in that condition increased with the severity of vestibular impairment but not with disease duration. In the absence of visual control, impaired otolith input destabilizes BVF with head retroflexion. Stimulating deficient SSC does not distinguish patients from controls possibly reflecting a shift of intersensory weighing toward proprioceptive-guided postural control. Accordingly, proprioceptive deprivation heavily destabilizes BVF, even when visual control is provided. PMID:28919878

Biomechanical Measures During Landing and Postural Stability Predict Second Anterior Cruciate Ligament Injury After Anterior Cruciate Ligament Reconstruction and Return to Sport

PubMed Central

Paterno, Mark V.; Schmitt, Laura C.; Ford, Kevin R.; Rauh, Mitchell J.; Myer, Gregory D.; Huang, Bin; Hewett, Timothy E.

2016-01-01

Background Athletes who return to sport participation after anterior cruciate ligament reconstruction (ACLR) have a higher risk of a second anterior cruciate ligament injury (either reinjury or contralateral injury) compared with non–anterior cruciate ligament–injured athletes. Hypotheses Prospective measures of neuromuscular control and postural stability after ACLR will predict relative increased risk for a second anterior cruciate ligament injury. Study Design Cohort study (prognosis); Level of evidence, 2. Methods Fifty-six athletes underwent a prospective biomechanical screening after ACLR using 3-dimensional motion analysis during a drop vertical jump maneuver and postural stability assessment before return to pivoting and cutting sports. After the initial test session, each subject was followed for 12 months for occurrence of a second anterior cruciate ligament injury. Lower extremity joint kinematics, kinetics, and postural stability were assessed and analyzed. Analysis of variance and logistic regression were used to identify predictors of a second anterior cruciate ligament injury. Results Thirteen athletes suffered a subsequent second anterior cruciate ligament injury. Transverse plane hip kinetics and frontal plane knee kinematics during landing, sagittal plane knee moments at landing, and deficits in postural stability predicted a second injury in this population (C statistic = 0.94) with excellent sensitivity (0.92) and specificity (0.88). Specific predictive parameters included an increase in total frontal plane (valgus) movement, greater asymmetry in internal knee extensor moment at initial contact, and a deficit in single-leg postural stability of the involved limb, as measured by the Biodex stability system. Hip rotation moment independently predicted second anterior cruciate ligament injury (C = 0.81) with high sensitivity (0.77) and specificity (0.81). Conclusion Altered neuromuscular control of the hip and knee during a dynamic landing task and postural stability deficits after ACLR are predictors of a second anterior cruciate ligament injury after an athlete is released to return to sport. PMID:20702858

Effects of neck exercise on high-school students' neck-shoulder posture.

PubMed

Lee, Myoung-Hyo; Park, Su-Jin; Kim, Jin-Sang

2013-05-01

[Purpose] This study examined the effects of deep flexor muscle-strengthening exercise on the neck-shoulder posture, and the strength and endurance of the deep flexor muscles of high-school students. [Subjects] The subjects were 30 seventeen-year-old female high-school students who complained about bad posture and chronic neck-shoulder pain. They were randomly divided into an experimental group of 15 subjects, who performed a deep flexor muscle-strengthening exercise and a control group of 15 subjects, who performed a basic stretching exercise. [Methods] The experimental group of 15 subjects performed a deep flexor muscle-strengthening exercise consisting of low-load training of the cranio-cervical flexor muscle, and the control group of 15 subjects performed a basic stretching exercise consisting of seven motions. [Results] The experimental group showed statistically significant changes in head tilt angle, neck flexion angle, forward shoulder angle, and the result of the cranio-cervical flexion test after the training. In contrast, the control group showed no statistically significant changes in these measures following the training. When the results of the groups were compared, statistically significant differences were found for all items between the experimental group and the control group. [Conclusion] Strengthening cranio-cervical flexor muscles is important for the adjustment of neck posture, and maintaining their stability is required to improve neck-shoulder posture.

Voluntarily controlled but not merely observed visual feedback affects postural sway

PubMed Central

Asai, Tomohisa; Hiromitsu, Kentaro; Imamizu, Hiroshi

2018-01-01

Online stabilization of human standing posture utilizes multisensory afferences (e.g., vision). Whereas visual feedback of spontaneous postural sway can stabilize postural control especially when observers concentrate on their body and intend to minimize postural sway, the effect of intentional control of visual feedback on postural sway itself remains unclear. This study assessed quiet standing posture in healthy adults voluntarily controlling or merely observing visual feedback. The visual feedback (moving square) had either low or high gain and was either horizontally flipped or not. Participants in the voluntary-control group were instructed to minimize their postural sway while voluntarily controlling visual feedback, whereas those in the observation group were instructed to minimize their postural sway while merely observing visual feedback. As a result, magnified and flipped visual feedback increased postural sway only in the voluntary-control group. Furthermore, regardless of the instructions and feedback manipulations, the experienced sense of control over visual feedback positively correlated with the magnitude of postural sway. We suggest that voluntarily controlled, but not merely observed, visual feedback is incorporated into the feedback control system for posture and begins to affect postural sway. PMID:29682421

Treatment and retention of relapsed anterior open-bite with low tongue posture and tongue-tie: A 10-year follow-up

PubMed Central

Seo, Yu-Jin; Kim, Su-Jung; Munkhshur, Janchivdorj; Chung, Kyu-Rhim; Ngan, Peter

2014-01-01

The purpose of the current report is to present 6-year long-term stability and 10-year follow-up data for an adult patient who was treated with a tongue elevator for relapsed anterior open-bite. The 19-year-old male patient presented with the chief complaint of difficulty in chewing his food. Collectively, clinical and radiographic examinations revealed an anterior open-bite, low tongue posture, and tongue-tie. The patient opted for orthodontic treatment alone, without any surgical procedure. A lingual frenectomy was recommended to avoid the risk of relapse, but the patient declined because he was not experiencing tongue discomfort. Initial treatment of the anterior open-bite with molar intrusion and tongue exercises was successful, but relapse occurred during the retention period. A tongue elevator was used for retreatment, because the approach was minimally invasive and suited the patient's requirements regarding discomfort, cost, and time. The appliance changed the tongue posture and generated an altered tongue force, which ultimately resulted in intrusive dentoalveolar effects, and a subsequent counterclockwise rotation of the mandible. The results showed long-term stability and were maintained for six years through continual use of the tongue elevator. The results of this case indicated that a tongue elevator could be used not only as an alternative treatment for open-bite, but also as an active retainer. PMID:25133135

Postural stability of sitting women.

PubMed

Nag, Pranab K; Vyas, Heer; Nag, Anjali; Pal, Swati

2013-01-01

The study examined the utility of stabilometric dimensions and explored whether the changes in sitting postures were manifested in functional measures of postural control. Eleven women participated in the study, which used 11 chair sitting postures: arms on laps or arms right angled; armrest at a height of 17, 20 and 23 cm; with or without backrest; slouch or straight back; legs right angled at knees or crossed legs. The backrest and armrest shifted 16.3% of body weight from a seat pan. The characteristics of stabilometric dimensions evaluated the influence of seat components and sitting behaviour on postural balance. The study attempted to evaluate stability and its application in human-seat interface design.

Does a crouched leg posture enhance running stability and robustness?

PubMed

Blum, Yvonne; Birn-Jeffery, Aleksandra; Daley, Monica A; Seyfarth, Andre

2011-07-21

Humans and birds both walk and run bipedally on compliant legs. However, differences in leg architecture may result in species-specific leg control strategies as indicated by the observed gait patterns. In this work, control strategies for stable running are derived based on a conceptual model and compared with experimental data on running humans and pheasants (Phasianus colchicus). From a model perspective, running with compliant legs can be represented by the planar spring mass model and stabilized by applying swing leg control. Here, linear adaptations of the three leg parameters, leg angle, leg length and leg stiffness during late swing phase are assumed. Experimentally observed kinematic control parameters (leg rotation and leg length change) of human and avian running are compared, and interpreted within the context of this model, with specific focus on stability and robustness characteristics. The results suggest differences in stability characteristics and applied control strategies of human and avian running, which may relate to differences in leg posture (straight leg posture in humans, and crouched leg posture in birds). It has been suggested that crouched leg postures may improve stability. However, as the system of control strategies is overdetermined, our model findings suggest that a crouched leg posture does not necessarily enhance running stability. The model also predicts different leg stiffness adaptation rates for human and avian running, and suggests that a crouched avian leg posture, which is capable of both leg shortening and lengthening, allows for stable running without adjusting leg stiffness. In contrast, in straight-legged human running, the preparation of the ground contact seems to be more critical, requiring leg stiffness adjustment to remain stable. Finally, analysis of a simple robustness measure, the normalized maximum drop, suggests that the crouched leg posture may provide greater robustness to changes in terrain height. Copyright © 2011 Elsevier Ltd. All rights reserved.

INFLUENCE OF INJURY ON DYNAMIC POSTURAL CONTROL IN RUNNERS

PubMed Central

Klusendorf, Anna; Kernozek, Thomas

2016-01-01

ABSTRACT Background Injury has been linked with altered postural control in active populations. The association between running injury and dynamic postural control has not been examined. Hypothesis/Purpose The purpose of this study was to examine dynamic postural control in injured and uninjured runners using the Star Excursion Balance Test (SEBT), Time to Stabilization (TTS) of ground reaction forces following a single-leg landing, and postural stability indices reflecting the fluctuations in GRFs during single-leg landing and stabilization tasks (forward and lateral hop). It was hypothesized that dynamic postural control differences would exist between runners with a history of injury that interrupted training for ≥7 days (INJ) when compared to runners without injury (CON). Design Case-control study Methods Twenty-two INJ (14 F, 8 M; 23.7 ± 2.1 y; 22.3 ± 2.8 kg/m2; 29.5 ± 16.3 mi/wk) currently running > 50% pre-injury mileage without pain were compared with twenty-two matched CON (14F, 8M; 22.7 ± 1.2 y; 22.7 ± 2.7 kg/m2; 31.2 ± 19.6 mi/wk). INJ group was stratified by site of injury into two groups (Hip/Thigh/Knee and Lower Leg/Ankle/Foot) for secondary analysis. Leg length-normalized anterior, posterolateral, and posteromedial reach distances on the SEBT, medial/lateral and anterior/posterior ground reaction force TTS, directional postural stability indices, and a composite dynamic postural stability index (DPSI), were assessed using mixed model ANOVA (α=0.05) and effect sizes (d). Results No group X direction interaction or group differences were observed for the SEBT (p=0.51, 0.71) or TTS (p=0.83, 0.72) measures. A group X direction interaction was found for postural stability indices during the forward landing task (p<0.01). Both Hip/Thigh/Knee and Lower leg/Ankle/Foot INJ groups demonstrated a greater vertical postural stability index (VPSI) (p=0.01 for both, d=0.80, 0.95) and DPSI (p=0.01, 0.02, d=0.75, 0.93) when compared to CON suggesting impaired balance control. A group X direction interaction was also found for postural stability indices during the lateral landing task (p=0.03). Only the Hip/Thigh/Knee INJ runners displayed a greater VPSI (p=0.01, d=0.91) and DPSI (p=0.017, d=0.89) when compared to CON. Conclusions When compared to CON, INJ runners demonstrated impaired dynamic control of vertical forces when performing the single leg landing and stabilization tasks. Clinicians should consider addressing dynamic control of vertical loads through functional tasks during the rehabilitation of running injury. Level of Evidence Level 3 PMID:27274423

Dynamic Imbalance Analysis and Stability Control of Galloping Gait for a Passive Quadruped Robot

PubMed Central

Wang, Chunlei; Zhang, Ting; Wei, Xiaohui; Long, Yongjun; Wang, Shigang

2015-01-01

Some imbalance and balance postures of a passive quadruped robot with a simplified mathematical model are studied. Through analyzing the influence of the touchdown angle of the rear leg on the posture of the trunk during the flight phase, the stability criterion is concluded: the closer are the two moments which are the zero time of the pitching angle and the peak time of the center of mass, the better is the stability of the trunk posture during the flight phase. Additionally, the validity of the stability criterion is verified for the cat, greyhound, lion, racehorse, basset hound, and giraffe. Furthermore, the stability criterion is also applicable when the center of the mass of body is shifted. Based on the stability criterion, the necessary and sufficient condition of the galloping stability for the quadruped robot is proposed to attain a controlled thrust. The control strategy is designed by an optimization dichotomy algorithm for seeking the zero point of the balance condition. Through the control results, it is demonstrated that the imbalance posture of the trunk could be stabilized by adjusting the stiffness of four legs. PMID:27110095

Disruption of postural readaptation by inertial stimuli following space flight

NASA Technical Reports Server (NTRS)

Black, F. O.; Paloski, W. H.; Reschke, M. F.; Igarashi, M.; Guedry, F.; Anderson, D. J.

1999-01-01

Postural instability (relative to pre-flight) has been observed in all shuttle astronauts studied upon return from orbital missions. Postural stability was more closely examined in four shuttle astronaut subjects before and after an 8 day orbital mission. Results of the pre- and post-flight postural stability studies were compared with a larger (n = 34) study of astronauts returning from shuttle missions of similar duration. Results from both studies indicated that inadequate vestibular feedback was the most significant sensory deficit contributing to the postural instability observed post flight. For two of the four IML-1 astronauts, post-flight postural instability and rate of recovery toward their earth-normal performance matched the performance of the larger sample. However, post-flight postural control in one returning astronaut was substantially below mean performance. This individual, who was within normal limits with respect to postural control before the mission, indicated that recovery to pre-flight postural stability was also interrupted by a post-flight pitch plane rotation test. A similar, though less extreme departure from the mean recovery trajectory was present in another astronaut following the same post-flight rotation test. The pitch plane rotation stimuli included otolith stimuli in the form of both transient tangential and constant centripetal linear acceleration components. We inferred from these findings that adaptation on orbit and re-adaptation on earth involved a change in sensorimotor integration of vestibular signals most likely from the otolith organs.

Y balance test has no correlation with the Stability Index of the Biodex Balance System.

PubMed

Almeida, Gabriel Peixoto Leão; Monteiro, Isabel Oliveira; Marizeiro, Débora Fortes; Maia, Laísa Braga; de Paula Lima, Pedro Olavo

2017-02-01

A cross-sectional study design. The Stability Index of the Biodex Balance System (SI-BBS) and Y Balance Test (YBT) has been used in studies assessing postural stability but no studies have verified the association of the YBT with the SI-BBS. To analyze the association of the Y Balance Test (YBT) with the Stability Index of the Biodex Balance System (SI-BBS) to evaluate postural stability. Forty participants who engaged in recreational physical activities, 12 of whom had a history of injury to the lower limbs. Was used the SI-BBS and the anterior, posterolateral, posteromedial, and composite measures of the YBT. The order of execution of the tests and of the lower limbs evaluated was randomized and blind tested by two evaluators. Pearson's correlation coefficient was used to check the strength of the relationship between the distances achieved on the YBT and the SI-BBS. The YBT showed excellent reliability in the anterior, posteromedial, and posterolateral directions. However, the YBT showed no statistically significant correlation with any variables in the SI-BBS, indicating poor validity between YBT and SI-BBS assessments of postural stability in people with and without history of lower limb injuries. The results of this study showed the YBT is not correlated with the SI-BBS as an assessment of postural stability. This finding has implications for researchers and clinicians using YBT results as the only measure of postural stability. Copyright © 2016 Elsevier Ltd. All rights reserved.

Postural Control During Cascade Ball Juggling: Effects of Expertise and Base of Support.

PubMed

Rodrigues, Sérgio T; Polastri, Paula F; Gotardi, Gisele C; Aguiar, Stefane A; Mesaros, Marcelo R; Pestana, Mayara B; Barbieri, Fabio A

2016-08-01

Cascade ball juggling is a complex perceptual motor skill which requires efficient postural stabilization. The aim of this study was to investigate effects of experience (expert and intermediate groups) and foot distance (wide and narrow stances) on body sway of jugglers during three ball cascade juggling. A total of 10 expert jugglers and 11 intermediate jugglers participated in this study. Participants stood barefoot on the force plate (some participants wore a gaze tracking system), with feet maintained in wide and narrow conditions and performed three 40-seconds trials of the three-ball juggling task. Dependent variables were sway mean velocity, amplitude, mean frequency, number of ball cycles, fixation number, mean duration and its variability, and area of gaze displacement. Two-way analyses of variance with factors for group and condition were conducted. Experts' body sway was characterized by lower velocity and smaller amplitude as compared to intermediate group. Interestingly, the more challenging (narrow) basis of support caused significant attenuation in body sway only for the intermediate group. These data suggest that expertise in cascade juggling was associated with refined postural control. © The Author(s) 2016.

Investigation of the Differential Contributions of Superficial and Deep Muscles on Cervical Spinal Loads with Changing Head Postures

PubMed Central

Cheng, Chih-Hsiu; Chien, Andy; Hsu, Wei-Li; Chen, Carl Pai-Chu; Cheng, Hsin-Yi Kathy

2016-01-01

Cervical spinal loads are predominately influenced by activities of cervical muscles. However, the coordination between deep and superficial muscles and their influence on the spinal loads is not well understood. This study aims to document the changes of cervical spinal loads and the differential contributions of superficial and deep muscles with varying head postures. Electromyography (EMG) of cervical muscles from seventeen healthy adults were measured during maximal isometric exertions for lateral flexion (at 10°, 20° and terminal position) as well as flexion/extension (at 10°, 20°, 30°, and terminal position) neck postures. An EMG-assisted optimization approach was used to estimate the muscle forces and subsequent spinal loads. The results showed that compressive and anterior-posterior shear loads increased significantly with neck flexion. In particular, deep muscle forces increased significantly with increasing flexion. It was also determined that in all different static head postures, the deep muscle forces were greater than those of the superficial muscle forces, however, such pattern was reversed during peak efforts where greater superficial muscle forces were identified with increasing angle of inclination. In summary, the identification of significantly increased spinal loads associated with increased deep muscle activation during flexion postures, implies higher risks in predisposing the neck to occupationally related disorders. The results also explicitly supported that deep muscles play a greater role in maintaining stable head postures where superficial muscles are responsible for peak exertions and reinforcing the spinal stability at terminal head postures. This study provided quantitative data of normal cervical spinal loads and revealed motor control strategies in coordinating the superficial and deep muscles during physical tasks. PMID:26938773

Investigation of the Differential Contributions of Superficial and Deep Muscles on Cervical Spinal Loads with Changing Head Postures.

PubMed

Cheng, Chih-Hsiu; Chien, Andy; Hsu, Wei-Li; Chen, Carl Pai-Chu; Cheng, Hsin-Yi Kathy

2016-01-01

Cervical spinal loads are predominately influenced by activities of cervical muscles. However, the coordination between deep and superficial muscles and their influence on the spinal loads is not well understood. This study aims to document the changes of cervical spinal loads and the differential contributions of superficial and deep muscles with varying head postures. Electromyography (EMG) of cervical muscles from seventeen healthy adults were measured during maximal isometric exertions for lateral flexion (at 10°, 20° and terminal position) as well as flexion/extension (at 10°, 20°, 30°, and terminal position) neck postures. An EMG-assisted optimization approach was used to estimate the muscle forces and subsequent spinal loads. The results showed that compressive and anterior-posterior shear loads increased significantly with neck flexion. In particular, deep muscle forces increased significantly with increasing flexion. It was also determined that in all different static head postures, the deep muscle forces were greater than those of the superficial muscle forces, however, such pattern was reversed during peak efforts where greater superficial muscle forces were identified with increasing angle of inclination. In summary, the identification of significantly increased spinal loads associated with increased deep muscle activation during flexion postures, implies higher risks in predisposing the neck to occupationally related disorders. The results also explicitly supported that deep muscles play a greater role in maintaining stable head postures where superficial muscles are responsible for peak exertions and reinforcing the spinal stability at terminal head postures. This study provided quantitative data of normal cervical spinal loads and revealed motor control strategies in coordinating the superficial and deep muscles during physical tasks.

Managing a Female Patient with Left Low Back Pain and Sacroiliac Joint Pain with Therapeutic Exercise: A Case Report

PubMed Central

2011-01-01

ABSTRACT Purpose: The purpose of this case study is to describe the management of a female patient with chronic left low back pain and sacroiliac joint pain (LBP/SIJP) using unique unilateral exercises developed by the Postural Restoration Institute (PRI) to address pelvic asymmetry and left hip capsule restriction, which is consistent with a Right Handed and Left Anterior Interior Chain pattern of postural asymmetry. Client Description: The client was 65-year-old woman with a 10-month history of constant left LBP/SIJP and leg pain. Intervention: The patient was seen six times to correct pelvic position/posture and left hip posterior capsule restriction via (1) muscle activation (left hamstrings, adductor magnus, and anterior gluteus medius) and (2) left hip adduction to lengthen the left posterior capsule/ischiofemoral ligament. Stabilization exercises included bilateral hamstrings, gluteus maximus, adductors, and abdominals to maintain pelvic position/posture. Measures and Outcome: Left Ober's test (initially positive) was negative at discharge. Pain as measured on the Numeric Pain Rating Scale (initially 1/10 at best and 8/10 at worst) was 0/10–0/10 at discharge. Oswestry Disability Index score (initially 20%) was 0% at discharge. The patient no longer had numbness in her left leg, and sexual intercourse had become pain free. Implications: Interventions to restore and maintain the optimal position of pelvis and hip (femoral head in the acetabulum) may be beneficial for treating patients with chronic LBP/SIJP. The patient's pain was eliminated 13 days after she first performed three exercises to reposition the pelvis and restore left posterior hip capsule extensibility and internal rotation. PMID:22379254

Balance Training Reduces Brain Activity during Motor Simulation of a Challenging Balance Task in Older Adults: An fMRI Study

PubMed Central

Ruffieux, Jan; Mouthon, Audrey; Keller, Martin; Mouthon, Michaël; Annoni, Jean-Marie; Taube, Wolfgang

2018-01-01

Aging is associated with a shift from an automatic to a more cortical postural control strategy, which goes along with deteriorations in postural stability. Although balance training has been shown to effectively counteract these behavioral deteriorations, little is known about the effect of balance training on brain activity during postural tasks in older adults. We, therefore, assessed postural stability and brain activity using fMRI during motor imagery alone (MI) and in combination with action observation (AO; i.e., AO+MI) of a challenging balance task in older adults before and after 5 weeks of balance training. Results showed a nonsignificant trend toward improvements in postural stability after balance training, accompanied by reductions in brain activity during AO+MI of the balance task in areas relevant for postural control, which have been shown to be over-activated in older adults during (simulation of) motor performance, including motor, premotor, and multisensory vestibular areas. This suggests that balance training may reverse the age-related cortical over-activations and lead to changes in the control of upright posture toward the one observed in young adults. PMID:29472847

Balance Training Reduces Brain Activity during Motor Simulation of a Challenging Balance Task in Older Adults: An fMRI Study.

PubMed

Ruffieux, Jan; Mouthon, Audrey; Keller, Martin; Mouthon, Michaël; Annoni, Jean-Marie; Taube, Wolfgang

2018-01-01

Aging is associated with a shift from an automatic to a more cortical postural control strategy, which goes along with deteriorations in postural stability. Although balance training has been shown to effectively counteract these behavioral deteriorations, little is known about the effect of balance training on brain activity during postural tasks in older adults. We, therefore, assessed postural stability and brain activity using fMRI during motor imagery alone (MI) and in combination with action observation (AO; i.e., AO+MI) of a challenging balance task in older adults before and after 5 weeks of balance training. Results showed a nonsignificant trend toward improvements in postural stability after balance training, accompanied by reductions in brain activity during AO+MI of the balance task in areas relevant for postural control, which have been shown to be over-activated in older adults during (simulation of) motor performance, including motor, premotor, and multisensory vestibular areas. This suggests that balance training may reverse the age-related cortical over-activations and lead to changes in the control of upright posture toward the one observed in young adults.

Postural Stability Margins as a Function of Support Surface Slopes.

PubMed

Dutt-Mazumder, Aviroop; Slobounov, Seymon M; Challis, John Henry; Newell, Karl Maxim

2016-01-01

This investigation examined the effects of slope of the surface of support (35°, 30°, 20°, 10° Facing(Toe) Down, 0° Flat and 10°, 20°, 25° Facing (Toe) Up) and postural orientation on the margins of postural stability in quiet standing of young adults. The findings showed that the center of pressure-CoP (displacement, area and length) had least motion at the baseline (0° Flat) platform condition that progressively increased as a function of platform angle in both facing up and down directions. The virtual time to collision (VTC) dynamics revealed that the spatio-temporal margins to the functional stability boundary were progressively smaller and the VTC time series also more regular (SampEn-Sample Entropy) as slope angle increased. Surface slope induces a restricted stability region with lower dimension VTC dynamics that is more constrained when postural orientation is facing down the slope. These findings provide further evidence that VTC acts as a control variable in standing posture that is influenced by the emergent dynamics of the individual-environment-task interaction.

Military personnel with self-reported ankle injuries do not demonstrate deficits in dynamic postural stability or landing kinematics.

PubMed

Bansbach, Heather M; Lovalekar, Mita T; Abt, John P; Rafferty, Deirdre; Yount, Darcie; Sell, Timothy C

2017-08-01

The odds of sustaining non-contact musculoskeletal injuries are higher in Special Operations Forces operators than in infantry soldiers. The ankle is one of the most commonly injured joints, and once injured can put individuals at risk for reinjury. The purpose of this study was to determine if any differences in postural stability and landing kinematics exist between operators with a self-reported ankle injury in the past one year and uninjured controls. A total of 55 Special Operations Forces operators were included in this analysis. Comparisons were made between operators with a self-reported ankle injury within one-year of their test date (n=11) and healthy matched controls (n=44). Comparisons were also made between injured and uninjured limbs within the injured group. Dynamic postural stability and landing kinematics at the ankle, knee, and hip were assessed during a single-leg jump-landing task. Comparisons were made between groups with independent t-tests and within the injured group between limbs using paired t-tests. There were no significant differences in dynamic postural stability index or landing kinematics between the injured and uninjured groups. Anterior-posterior stability index was significantly higher on the uninjured limb compared to the injured limb within the injured group (P=0.02). Single ankle injuries sustained by operators may not lead to deficits in dynamic postural stability. Dynamic postural stability index and landing kinematics within one year after injury were either not affected by the injuries reported, or injured operators were trained back to baseline measures through rehabilitation and daily activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Does robotic gait training improve balance in Parkinson's disease? A randomized controlled trial.

PubMed

Picelli, Alessandro; Melotti, Camilla; Origano, Francesca; Waldner, Andreas; Gimigliano, Raffaele; Smania, Nicola

2012-09-01

Treadmill training (with or without robotic assistance) has been reported to improve balance skills in patients with Parkinson's disease (PD). However, its effectiveness on postural instability has been evaluated mainly in patients with mild to moderate PD (Hoehn & Yahr stage ≤3). Patients with more severe disease may benefit from robot-assisted gait training performed by the Gait-Trainer GT1, as a harness supports them with their feet placed on motor-driven footplates. The aim of this study was to determine whether robot-assisted gait training could have a positive influence on postural stability in patients with PD at Hoehn & Yahr stage 3-4. Thirty-four patients with PD at Hoehn & Yahr stage 3-4 were randomly assigned into two groups. All patients received twelve, 40-min treatment sessions, three days/week, for four consecutive weeks. The Robotic Training group (n = 17) underwent robot-assisted gait training, while the Physical Therapy group (n = 17) underwent a training program not specifically aimed at improving postural stability. Patients were evaluated before, immediately after and 1-month post-treatment. Primary outcomes were: Berg Balance scale; Nutt's rating. A significant improvement was found after treatment on the Berg Balance Scale and the Nutt's rating in favor of the Robotic Training group (Berg: 43.44 ± 2.73; Nutt: 1.38 ± 0.50) compared to the Physical Therapy group (Berg: 37.27 ± 5.68; Nutt: 2.07 ± 0.59). All improvements were maintained at the 1-month follow-up evaluation. Robot-assisted gait training may improve postural instability in patients with PD at Hoehn & Yahr stage 3-4. Copyright © 2012 Elsevier Ltd. All rights reserved.

Classification of posture maintenance data with fuzzy clustering algorithms

NASA Technical Reports Server (NTRS)

Bezdek, James C.

1991-01-01

Sensory inputs from the visual, vestibular, and proprioreceptive systems are integrated by the central nervous system to maintain postural equilibrium. Sustained exposure to microgravity causes neurosensory adaptation during spaceflight, which results in decreased postural stability until readaptation occurs upon return to the terrestrial environment. Data which simulate sensory inputs under various conditions were collected in conjunction with JSC postural control studies using a Tilt-Translation Device (TTD). The University of West Florida proposed applying the Fuzzy C-Means Clustering (FCM) Algorithms to this data with a view towards identifying various states and stages. Data supplied by NASA/JSC were submitted to the FCM algorithms in an attempt to identify and characterize cluster substructure in a mixed ensemble of pre- and post-adaptational TTD data. Following several unsuccessful trials with FCM using a full 11 dimensional data set, a set of two channels (features) were found to enable FCM to separate pre- from post-adaptational TTD data. The main conclusions are that: (1) FCM seems able to separate pre- from post-TTD subject no. 2 on the one trial that was used, but only in certain subintervals of time; and (2) Channels 2 (right rear transducer force) and 8 (hip sway bar) contain better discrimination information than other supersets and combinations of the data that were tried so far.

Standing postural instability in patients with schizophrenia: Relationships with psychiatric symptoms, anxiety, and the use of neuroleptic medications.

PubMed

Matsuura, Yukako; Fujino, Haruo; Hashimoto, Ryota; Yasuda, Yuka; Yamamori, Hidenaga; Ohi, Kazutaka; Takeda, Masatoshi; Imura, Osamu

2015-03-01

The purpose of this study was to assess postural instability in patients with schizophrenia using a pressure-sensitive platform and to examine the effects of anxiety, psychiatric symptoms, and the use of neuroleptic medications on postural sway. Participants were 23 patients with schizophrenia and 23 healthy controls. We found that the patients showed greater overall postural instability than the controls. Furthermore, they demonstrated greater instability when the test was performed with the eyes closed than with the eyes open. However, removal of visual input had less impact on the indices of postural instability in the patients than in the controls, suggesting that schizophrenia is associated with difficulties in integrating visual information and proprioceptive signals. Furthermore, in contrast to the controls, anxiety exacerbated postural instability in the patients. There were significant associations between postural stability and psychiatric symptoms in the patients without extrapyramidal symptoms, whereas medication dose did not significantly correlate with postural stability. Copyright © 2015 Elsevier B.V. All rights reserved.

U.S. Overseas Military Posture: Relative Costs and Strategic Benefits

DTIC Science & Technology

2013-01-01

C O R P O R A T I O N RESE ARCH BR IEF U.S. Overseas Military Posture Relative Costs and Strategic Benefits The United States is at an inflection...posture translates into benefits ; the risks that different poten- tial postures pose and the cost of maintaining these postures; how these benefits ...changes. Strategic Benefits of Overseas Posture Overseas presence contributes to contingency responsiveness, deterrence of adversaries and assurance of

Stabilisation times after transitions to standing from different working postures.

PubMed

DiDomenico, Angela; McGorry, Raymond W; Banks, Jacob J

2016-10-01

Transitioning to standing after maintaining working postures may result in imbalance and could elicit a fall. The objective of this study was to quantify the magnitude of imbalance using a stabilisation time metric. Forty-five male participants completed three replications of conditions created by one of four working postures (bent at waist, squat, forward kneel, reclined kneel) and three durations within posture. Participants transitioned to quiet standing at a self-selected pace. Stabilisation time, based on changes in centre of pressure velocity, was used to indicate the initiation of steady state while standing. Stabilisation time was significantly affected by static postures but not duration within posture. The largest stabilisation times resulted from transitions initiated from a bent at waist posture. The smallest were associated with the kneeling postures, which were not significantly different from each other. Findings may lead to recommendations for redesign of tasks, particularly in high-risk environments such as construction. Statement of Relevance: Task performance on the jobsite often requires individuals to maintain non-erect postures. This study suggests that working posture affects stabilisation during transition to a standing position. Bending at the waist and squatting resulted in longer stabilisation times, whereas both kneeling postures evaluated resulted in greater imbalance but for a shorter duration.

Influence of both cutaneous input from the foot soles and visual information on the control of postural stability in dyslexic children.

PubMed

Goulème, Nathalie; Villeneuve, Philippe; Gérard, Christophe-Loïc; Bucci, Maria Pia

2017-07-01

Dyslexic children show impaired in postural stability. The aim of our study was to test the influence of foot soles and visual information on the postural control of dyslexic children, compared to non-dyslexic children. Postural stability was evaluated with TechnoConcept ® platform in twenty-four dyslexic children (mean age: 9.3±0.29years) and in twenty-four non-dyslexic children, gender- and age-matched, in two postural conditions (with and without foam: a 4-mm foam was put under their feet or not) and in two visual conditions (eyes open and eyes closed). We measured the surface area, the length and the mean velocity of the center of pressure (CoP). Moreover, we calculated the Romberg Quotient (RQ). Our results showed that the surface area, length and mean velocity of the CoP were significantly greater in the dyslexic children compared to the non-dyslexic children, particularly with foam and eyes closed. Furthermore, the RQ was significantly smaller in the dyslexic children and significantly greater without foam than with foam. All these findings suggest that dyslexic children are not able to compensate with other available inputs when sensorial inputs are less informative (with foam, or eyes closed), which results in poor postural stability. We suggest that the impairment of the cerebellar integration of all the sensorial inputs is responsible for the postural deficits observed in dyslexic children. Copyright © 2017 Elsevier B.V. All rights reserved.

Individuals with chronic ankle instability exhibit dynamic postural stability deficits and altered unilateral landing biomechanics: A systematic review.

PubMed

Simpson, Jeffrey D; Stewart, Ethan M; Macias, David M; Chander, Harish; Knight, Adam C

2018-06-13

To evaluate the literature regarding unilateral landing biomechanics and dynamic postural stability in individuals with and without chronic ankle instability (CAI). Four online databases (PubMed, ScienceDirect, Scopus, and SportDiscus) were searched from the earliest records to 31 January 2018, as well as reference sections of related journal articles, to complete the systematic search. Studies investigating the influence of CAI on unilateral landing biomechanics and dynamic postural stability were systematically reviewed and evaluated. Twenty articles met the criteria and were included in the systematic review. Individuals with CAI were found to have deficits in dynamic postural stability on the affected limb with medium to large effect sizes and altered lower extremity kinematics, most notably in the ankle and knee, with medium to large effect sizes. Additionally, greater loading rates and peak ground reaction forces, in addition to reductions in ankle muscle activity were also found in individuals with CAI during unilateral jump-landing tasks. Individuals with CAI demonstrate dynamic postural stability deficits, lower extremity kinematic alterations, and reduced neuromuscular control during unilateral jump-landings. These are likely factors that contribute recurrent lateral ankle sprain injuries during dynamic activity in individuals with CAI. Copyright © 2018 Elsevier Ltd. All rights reserved.

Postural stability changes during large vertical diplopia induced by prism wear in normal subjects.

PubMed

Matsuo, Toshihiko; Yamasaki, Hanako; Yasuhara, Hirotaka; Hasebe, Kayoko

2013-01-01

To test the effect of double vision on postural stability, we measured postural stability by electric stabilometry before prism-wearing and immediately, 15, 30, and 60min after continuous prism-wearing with 6 prism diopters in total (a 3-prism-diopter prism placed with the base up in front of one eye and with the base down in front of the other eye) in 20 normal adult individuals with their eyes open or closed. Changes in stabilometric parameters in the time course of 60min were analyzed statistically by repeated-measure analysis of variance. When subjectsｾ eyes were closed, the total linear length (cm) and the unit-time length (cm/sec) of the sway path were significantly shortened during the 60-minute prism-wearing (p＜0.05). No significant change was noted in any stabilometric parameters obtained with the eyes open during the time course. In conclusion, postural stability did not change with the eyes open in the condition of large vertical diplopia, induced by prism-wearing for 60min, while the stability became better when measured with the eyes closed. A postural control mechanism other than that derived from visual input might be reinforced under abnormal visual input such as non-fusionable diplopia.

Comparison of the Wii Balance Board and the BESS tool measuring postural stability in collegiate athletes.

PubMed

Guzman, Jill; Aktan, Nadine

2016-02-01

Concussions are a major health concern for athletes given the potential for these injuries in a wide range of sport activities. The leading concern for clinicians is that athletes are at risk for devastating consequences if they are not evaluated properly and cleared too early to return to play or competition. The evaluation of postural stability has been identified as an important aspect to the comprehensive management of such injuries. Clinicians are in need of a portable tool they can use in various settings to aid in decision making and health care delivery for concussed athletes. The Nintendo Wii Balance Board (Nintendo of America Inc., Redmond, Washington) is a portable, cost-effective tool that has the potential to aid in the evaluation of postural stability in concussed individuals. The purpose of this study was to evaluate the Wii Balance Board as an objective, user-friendly, cost effective, valid alternative tool for the measurement of postural stability in college athletes. This study questioned whether the Wii Balance Board, when compared to the Balance Error Scoring System (BESS), is an objective tool that can be used as an acceptable measurement of postural stability in college athletes. Copyright © 2015 Elsevier Inc. All rights reserved.

Rationale, principles and experimental evaluation of the concept of soft stabilization.

PubMed

Mulholland, Robert C; Sengupta, Dilip K

2002-10-01

The apparent clinical success of spinal stabilization methods that restrict rather than abolish movement in relieving mechanical back pain indicates that the concept of the aetiology of back pain should be reviewed. Further understanding of how degeneration affects disc biomechanics, and an understanding of how current soft stabilization systems alters them, may allow us to define more precisely what are the essential requirements of an ideal soft stabilization system. It appears that abnormal patterns of loading rather than abnormal movement are the reason that disc degeneration causes back pain in some patients. Abnormal load transmission is the principal cause of pain in osteoarthritic joints, and both osteotomy and, indeed, joint replacement succeed because they alter the load transmission across the joint. This concept is supported by the fact that abnormal patterns of stress distribution measured across the disc correlate with painful discs on discography. Clinically, it is often noted that back pain is primarily related to position or posture, rather than movement of the lumbar spine. Clinical success after solid fusion is unpredictable because it does not necessarily prevent painful loading across the disc, and also it may interfere with maintenance of sagittal balance in varying postures. The Graf ligament restricted flexion, and was modestly successful. It unfortunately increased the load over the posterior annulus. The Dynesys system reduces movement both in flexion and extension, and appears to be more successful. However, often it also unloads the disc to a degree that is unpredictable. The authors believe that this unloading of the disc is an important feature of a flexible stabilization system. A new a design of a flexible stabilization system has recently been described in an in vitro study, which unloads the disc by introduction of a load-sharing fulcrum near the axis of movement together with an elastic posterior ligament. This design produces maximal unloading of the disc, whilst allowing a restricted range of movement, which serves the important purpose of allowing the patient to maintain sagittal balance in varying postures.

Prediction of postural risk of fall initiation based on a two-variable description of body dynamics: position and velocity of center of mass.

PubMed

Honarvar, Mohammad Hadi; Nakashima, Motomu

2013-10-01

This research addresses the question: what is the risk of fall initiation at a certain human posture? There are postures from which no one is able to keep their balance and a fall will surely initiate (risk=1), and others from which everyone may regain their stability (risk=0). In other postures, only a portion of people can control their stability. One may interpret risk to chance of a fall to be initiated, and based on the portion of fallers assign a risk value to a given human posture (postural risk). Human posture can be mapped to a point in a 2-dimensional space: the x-v plane, the axes of which are horizontal components of the position and velocity of the center of mass of the body. For every pair of (x, v), the outcome of the balance recovery problem defines whether a person with a given strength level is able to regain their stability when released from a posture corresponding to that point. Using strength distribution data, we estimated the portion of the population who will initiate a fall if starting at a certain posture. A fast calculation approach is also introduced to replace the time-consuming method of solving the recovery problem many times. Postural risk of fall initiation for situations expressed by (x, v) pairs for the entire x-v plane is calculated and shown in a color-map. Copyright © 2013 Elsevier B.V. All rights reserved.

Adaptive changes in anticipatory postural adjustments with novel and familiar postural supports.

PubMed

Hall, Leanne M; Brauer, Sandra; Horak, Fay; Hodges, Paul W

2010-02-01

Anticipatory postural adjustments (APAs) serve to stabilize posture prior to initiation of voluntary movement. This study examined the effects of changes in postural support on APAs using novel and familiar support paradigms. We also investigated whether postural strategies were refined with practice and how the CNS responded when multiple supports were available. Twelve healthy subjects stood on dual force platforms and performed 20 randomized left and right rapid leg-lift tasks in response to a visual cue under four conditions: unsupported, bilateral handgrip, bite plate, and a combined handgrip and bite plate condition. Vertical ground reaction forces, electromyography of limb, trunk and jaw muscles, and forces exerted on the support apparatus were recorded. Shift in center-of-pressure amplitude and duration were reduced with increased support. Muscles were recruited in advance of the focal movement when able to contribute to stability, and activity was modulated based on the amount of support available. The CNS adapted anticipatory postural strategies immediately with changes in condition regardless of familiarity with the support; however, adaptation was only complete at the first repetition in conditions that involved familiar support strategies. Tasks that involved a novel bite strategy continued to adapt with practice. In the multiple support condition, both hand and bite strategies were immediately incorporated; however, the contribution of each was not identical to conditions where supports were provided individually. This study emphasizes the flexibility of the CNS to organize postural strategies to meet the demands of postural stability in both familiar and novel situations.

Contribution of Head Position, Standing Surface, and Vision to Postural Control in Community-Dwelling Older Adults.

PubMed

Pociask, Fredrick D; DiZazzo-Miller, Rosanne; Goldberg, Allon; Adamo, Diane E

2016-01-01

Postural control requires the integration of sensorimotor information to maintain balance and to properly position and orient the body in response to external stimuli. Age-related declines in peripheral and central sensory and motor function contribute to postural instability and falls. This study investigated the contribution of head position, standing surface, and vision on postural sway in 26 community-dwelling older adults. Participants were asked to maintain a stable posture under conditions that varied standing surface, head position, and the availability of visual information. Significant main and interaction effects were found for all three factors. Findings from this study suggest that postural sway responses require the integration of available sources of sensory information. These results have important implications for fall risks in older adults and suggest that when standing with the head extended and eyes closed, older adults may place themselves at risk for postural disequilibrium and loss of balance. Copyright © 2016 by the American Occupational Therapy Association, Inc.

Sport-specific balance.

PubMed

Zemková, Erika

2014-05-01

This review includes the latest findings based on experimental studies addressing sport-specific balance, an area of research that has grown dramatically in recent years. The main objectives of this work were to investigate the postural sway response to different forms of exercise under laboratory and sport-specific conditions, to examine how this effect can vary with expertise, and to provide examples of the association of impaired balance with sport performance and/or increasing risk of injury. In doing so, sports where body balance is one of the limiting factors of performance were analyzed. While there are no significant differences in postural stability between athletes of different specializations and physically active individuals during standing in a standard upright position (e.g., bipedal stance), they have a better ability to maintain balance in specific conditions (e.g., while standing on a narrow area of support). Differences in magnitude of balance impairment after specific exercises (rebound jumps, repeated rotations, etc.) and mainly in speed of its readjustment to baseline are also observed. Besides some evidence on an association of greater postural sway with the increasing risk of injuries, there are many myths related to the negative influence of impaired balance on sport performance. Though this may be true for shooting or archery, findings have shown that in many other sports, highly skilled athletes are able to perform successfully in spite of increased postural sway. These findings may contribute to better understanding of the postural control system under various performance requirements. It may provide useful knowledge for designing training programs for specific sports.

Comparison of postural stability between injured and uninjured ballet dancers.

PubMed

Lin, Cheng-Feng; Lee, I-Jung; Liao, Jung-Hsien; Wu, Hong-Wen; Su, Fong-Chin

2011-06-01

Ballet movements require a limited base of support; thus, ballet dancers require a high level of postural control. However, postural stability in ballet dancers is still unclear and needs to be understood. To evaluate ballet dancers' postural stability in performing single-leg standing, the en pointe task, and the first and fifth positions and to determine differences in task performance among healthy nondancers, healthy dancers, and dancers with ankle sprains. Controlled laboratory study. Injured dancers, uninjured dancers, and nondancers were recruited for this study (N = 33 age-matched participants; n= 11 per group). The tasks tested were single-leg standing with eyes open and closed, first position, fifth position, and en pointe. Center of pressure parameters were calculated from the ground-reaction force collected with 1 force plate. Analysis of variance was used to assess the differences of center of pressure parameters among 3 groups in single-leg standing; independent t test was used to examine the differences of center of pressure parameters between injured and uninjured dancers. During single-leg standing, injured dancers had significantly greater maximum displacement in the medial-lateral direction and total trajectory of center of pressure, compared with the uninjured dancers and nondancers. During the first and fifth positions, the injured dancers demonstrated significantly greater standard deviation of center of pressure position in the medial-lateral and anterior-posterior directions, compared with the uninjured dancers. During en pointe, the injured dancers had significantly greater maximum displacement in the medial-lateral direction and the anterior-posterior direction, compared with the uninjured dancers. The injured and uninjured dancers demonstrated differences in postural stability in the medial-lateral direction during single-leg standing and the ballet postures. Although the injured dancers received ballet training, their postural stability may still be inferior to that of the nondancers. This study is a first step in understanding that injured ballet dancers do not have the same postural stability as uninjured dancers and that it is even inferior to that of nondancers, which is important to understand for further study on rehabilitation. The future development of effective balance training programs for ballet dancers with ankle injuries should emphasize improvements in medial-lateral directional balance.

The effect of a haptic biofeedback system on postural control in patients with stroke: An experimental pilot study.

PubMed

Yasuda, Kazuhiro; Kaibuki, Naomi; Harashima, Hiroaki; Iwata, Hiroyasu

2017-06-01

Impaired balance in patients with hemiparesis caused by stroke is frequently related to deficits in the central integration of afferent inputs, and traditional rehabilitation reinforces excessive visual reliance by focusing on visual compensation. The present study investigated whether a balance task involving a haptic biofeedback (BF) system, which provided supplementary vibrotactile sensory cues associated with center-of-foot-pressure displacement, improved postural control in patients with stroke. Seventeen stroke patients were assigned to two groups: the Vibrotactile BF and Control groups. During the balance task (i.e., standing on a foam mat), participants in the Vibrotactile BF group tried to stabilize their postural sway while wearing the BF system around the pelvic girdle. In the Control group, participants performed an identical postural task without the BF system. Pre- and post-test measurements of postural control using a force plate revealed that the stability of bipedal posture in the Vibrotactile BF group was markedly improved compared with that in the Control group. A balance task involving a vibrotactile BF system improved postural stability in patients with stroke immediately. This confirms the potential of a haptic-based BF system for balance training, both in routine clinical practice and in everyday life.

Fall risks assessment among community dwelling elderly using wearable wireless sensors

NASA Astrophysics Data System (ADS)

Lockhart, Thurmon E.; Soangra, Rahul; Frames, Chris

2014-06-01

Postural stability characteristics are considered to be important in maintaining functional independence free of falls and healthy life style especially for the growing elderly population. This study focuses on developing tools of clinical value in fall prevention: 1) Implementation of sensors that are minimally obtrusive and reliably record movement data. 2) Unobtrusively gather data from wearable sensors from four community centers 3) developed and implemented linear and non-linear signal analysis algorithms to extract clinically relevant information using wearable technology. In all a total of 100 community dwelling elderly individuals (66 non-fallers and 34 fallers) participated in the experiment. All participants were asked to stand-still in eyes open (EO) and eyes closed (EC) condition on forceplate with one wireless inertial sensor affixed at sternum level. Participants' history of falls had been recorded for last 2 years, with emphasis on frequency and characteristics of falls. Any participant with at least one fall in the prior year were classified as faller and the others as non-faller. The results indicated several key factors/features of postural characteristics relevant to balance control and stability during quite stance and, showed good predictive capability of fall risks among older adults. Wearable technology allowed us to gather data where it matters the most to answer fall related questions, i.e. the community setting environments. This study opens new prospects of clinical testing using postural variables with a wearable sensor that may be relevant for assessing fall risks at home and patient environment in near future.

Postural Stability of Special Warfare Combatant-Craft Crewmen With Tactical Gear.

PubMed

Morgan, Paul M; Williams, Valerie J; Sell, Timothy C

The US Naval Special Warfare's Special Warfare Combatant-Craft Crewmen (SWCC) operate on small, high-speed boats while wearing tactical gear (TG). The TG increases mission safety and success but may affect postural stability, potentially increasing risk for musculoskeletal injury. Therefore, the purpose of this study was to examine the effects of TG on postural stability during the Sensory Organization Test (SOT). Eight SWCC performed the SOT on NeuroCom's Balance Manager with TG and with no tactical gear (NTG). The status of gear was performed in randomized order. The SOT consisted of six different conditions that challenge sensory systems responsible for postural stability. Each condition was performed for three trials, resulting in a total of 18 trials. Overall performance, each individual condition, and sensory system analysis (somatosensory, visual, vestibular, preference) were scored. Data were not normally distributed therefore Wilcoxon signed-rank tests were used to compare each variable (ρ = .05). No significant differences were found between NTG and TG tests. No statistically significant differences were detected under the two TG conditions. This may be due to low statistical power, or potentially insensitivity of the assessment. Also, the amount and distribution of weight worn during the TG conditions, and the SWCC's unstable occupational platform, may have contributed to the findings. The data from this sample will be used in future research to better understand how TG affects SWCC. The data show that the addition of TG used in our study did not affect postural stability of SWCC during the SOT. Although no statistically significant differences were observed, there are clinical reasons for continued study of the effect of increased load on postural stability, using more challenging conditions, greater surface perturbations, dynamic tasks, and heavier loads. 2016.

Enhanced balance associated with coordination training with stochastic resonance stimulation in subjects with functional ankle instability: an experimental trial.

PubMed

Ross, Scott E; Arnold, Brent L; Blackburn, J Troy; Brown, Cathleen N; Guskiewicz, Kevin M

2007-12-17

Ankle sprains are common injuries that often lead to functional ankle instability (FAI), which is a pathology defined by sensations of instability at the ankle and recurrent ankle sprain injury. Poor postural stability has been associated with FAI, and sports medicine clinicians rehabilitate balance deficits to prevent ankle sprains. Subsensory electrical noise known as stochastic resonance (SR) stimulation has been used in conjunction with coordination training to improve dynamic postural instabilities associated with FAI. However, unlike static postural deficits, dynamic impairments have not been indicative of ankle sprain injury. Therefore, the purpose of this study was to examine the effects of coordination training with or without SR stimulation on static postural stability. Improving postural instabilities associated with FAI has implications for increasing ankle joint stability and decreasing recurrent ankle sprains. This study was conducted in a research laboratory. Thirty subjects with FAI were randomly assigned to either a: 1) conventional coordination training group (CCT); 2) SR stimulation coordination training group (SCT); or 3) control group. Training groups performed coordination exercises for six weeks. The SCT group received SR stimulation during training, while the CCT group only performed coordination training. Single leg postural stability was measured after the completion of balance training. Static postural stability was quantified on a force plate using anterior/posterior (A/P) and medial/lateral (M/L) center-of-pressure velocity (COPvel), M/L COP standard deviation (COPsd), M/L COP maximum excursion (COPmax), and COP area (COParea). Treatment effects comparing posttest to pretest COP measures were highest for the SCT group. At posttest, the SCT group had reduced A/P COPvel (2.3 +/- 0.4 cm/s vs. 2.7 +/- 0.6 cm/s), M/L COPvel (2.6 +/- 0.5 cm/s vs. 2.9 +/- 0.5 cm/s), M/L COPsd (0.63 +/- 0.12 cm vs. 0.73 +/- 0.11 cm), M/L COPmax (1.76 +/- 0.25 cm vs. 1.98 +/- 0.25 cm), and COParea (0.13 +/- 0.03 cm2 vs. 0.16 +/- 0.04 cm2) than the pooled means of the CCT and control groups (P < 0.05). Reduced values in COP measures indicated postural stability improvements. Thus, six weeks of coordination training with SR stimulation enhanced postural stability. Future research should examine the use of SR stimulation for decreasing recurrent ankle sprain injury in physically active individuals with FAI.

Enhanced balance associated with coordination training with stochastic resonance stimulation in subjects with functional ankle instability: an experimental trial

PubMed Central

Ross, Scott E; Arnold, Brent L; Blackburn, J Troy; Brown, Cathleen N; Guskiewicz, Kevin M

2007-01-01

Background Ankle sprains are common injuries that often lead to functional ankle instability (FAI), which is a pathology defined by sensations of instability at the ankle and recurrent ankle sprain injury. Poor postural stability has been associated with FAI, and sports medicine clinicians rehabilitate balance deficits to prevent ankle sprains. Subsensory electrical noise known as stochastic resonance (SR) stimulation has been used in conjunction with coordination training to improve dynamic postural instabilities associated with FAI. However, unlike static postural deficits, dynamic impairments have not been indicative of ankle sprain injury. Therefore, the purpose of this study was to examine the effects of coordination training with or without SR stimulation on static postural stability. Improving postural instabilities associated with FAI has implications for increasing ankle joint stability and decreasing recurrent ankle sprains. Methods This study was conducted in a research laboratory. Thirty subjects with FAI were randomly assigned to either a: 1) conventional coordination training group (CCT); 2) SR stimulation coordination training group (SCT); or 3) control group. Training groups performed coordination exercises for six weeks. The SCT group received SR stimulation during training, while the CCT group only performed coordination training. Single leg postural stability was measured after the completion of balance training. Static postural stability was quantified on a force plate using anterior/posterior (A/P) and medial/lateral (M/L) center-of-pressure velocity (COPvel), M/L COP standard deviation (COPsd), M/L COP maximum excursion (COPmax), and COP area (COParea). Results Treatment effects comparing posttest to pretest COP measures were highest for the SCT group. At posttest, the SCT group had reduced A/P COPvel (2.3 ± 0.4 cm/s vs. 2.7 ± 0.6 cm/s), M/L COPvel (2.6 ± 0.5 cm/s vs. 2.9 ± 0.5 cm/s), M/L COPsd (0.63 ± 0.12 cm vs. 0.73 ± 0.11 cm), M/L COPmax (1.76 ± 0.25 cm vs. 1.98 ± 0.25 cm), and COParea (0.13 ± 0.03 cm2 vs. 0.16 ± 0.04 cm2) than the pooled means of the CCT and control groups (P < 0.05). Conclusion Reduced values in COP measures indicated postural stability improvements. Thus, six weeks of coordination training with SR stimulation enhanced postural stability. Future research should examine the use of SR stimulation for decreasing recurrent ankle sprain injury in physically active individuals with FAI. PMID:18086314

Postural stability is altered by the stimulation of pain but not warm receptors in humans.

PubMed

Blouin, Jean-Sébastien; Corbeil, Philippe; Teasdale, Normand

2003-10-17

It is now recognized that large diameter myelinated afferents provide the primary source of lower limb proprioceptive information for maintaining an upright standing position. Small diameter afferents transmitting noxious stimuli, however, can also influence motor behaviors. Despite the possible influence of pain on motor behaviors, the effects of pain on the postural control system have not been well documented. Two cutaneous heat stimulations (experiment 1: non-noxious 40 degrees C; experiment 2: noxious 45 degrees C) were applied bilaterally on the calves of the subject with two thermal grills to stimulate A delta and C warm receptors and nociceptors in order to examine their effects on postural stability. The non-noxious stimulation induced a gentle sensation of warmth and the noxious stimulation induced a perception of heat pain (visual analogue scores of 0 and 46 mm, respectively). For both experiments, ten healthy young adults were tested with and without heat stimulations of the lower limbs while standing upright on a force platform with eyes open, eyes closed and eyes closed with tendon co-vibration of tibialis anterior and triceps surae muscles. The center of pressure displacements were analyzed to examine how both stimulations affected the regulation of quiet standing and if the effects were exacerbated when vision was removed or ankle proprioception perturbed. The stimulation of the warm receptors (40 degrees C) did not induce any postural deterioration. With pain (45 degrees C), subjects showed a significant increase in standard deviation, range and mean velocity of postural oscillations as well as standard deviation of the center of pressure velocity. The effects of heat pain were exacerbated when subjects had both their eyes closed and ankle tendons vibrated (increased standard deviation of the center of pressure velocity and mean velocity of the center of pressure). A non-noxious stimulation (40 degrees C) of the small diameter afferents is not a sufficiently intense sensory stimulation to alter the control of posture. A painful stimulation (45 degrees C) of the skin thermoreceptors, however, yielded a deterioration of the postural control system. The observed deteriorating effects of the combined stimulation of nociceptors and Ia afferents (when ankle tendons were vibrated) could result from the convergence of these afferents at the spinal level. This could certainly lead to the hypothesis that individuals suffering from lower limb pain present alterations of the postural control mechanisms; especially populations already at risk of falling (for example, frail elderly) or populations suffering from concomitant lower limb pain and sensory deficits (for example, diabetic polyneuropathy).

Validity of the Nintendo Wii® balance board for the assessment of standing balance in Parkinson's disease.

PubMed

Holmes, Jeffrey D; Jenkins, Mary E; Johnson, Andrew M; Hunt, Michael A; Clark, Ross A

2013-04-01

Impaired postural stability places individuals with Parkinson's at an increased risk for falls. Given the high incidence of fall-related injuries within this population, ongoing assessment of postural stability is important. To evaluate the validity of the Nintendo Wii(®) balance board as a measurement tool for the assessment of postural stability in individuals with Parkinson's. Twenty individuals with Parkinson's participated. Subjects completed testing on two balance tasks with eyes open and closed on a Wii(®) balance board and biomechanical force platform. Bland-Altman plots and a two-way, random-effects, single measure intraclass correlation coefficient model were used to assess concurrent validity of centre-of-pressure data. Concurrent validity was demonstrated to be excellent across balance tasks (intraclass correlation coefficients = 0.96, 0.98, 0.92, 0.94). This study suggests that the Wii(®) balance board is a valid tool for the quantification of postural stability among individuals with Parkinson's.

Comparison of jump-landing protocols with Biodex Balance System as measures of dynamic postural stability in athletes.

PubMed

Krkeljas, Zarko

2017-07-21

The objective of the study was to determine whether a relationship exists between the two common methods for assessing postural stability in athletes: the time-to-stabilisation (TTS) via force-plate and the Biodex Balance System (BBS). The conditions under which these measurements assess dynamic postural control may not provide sufficient feedback to practitioners. Fourty-four amateur soccer players with no history of musculoskeletal disorders volunteered for the study. Pearson correlation was used to compare the anterior-posterior (AP), medio-lateral (ML), and the overall stability indexes measured by BBS, with the corresponding parameters of TTS assessed via force plate. There was no significant correlation between any parameters of dynamic stability measured by force-plate and the stability indexes. However, there was a significant correlation between the resulting vectors and the AP component of TTS for each jump protocol. Furthermore, forward drop landing exhibited shortest TTS in AP direction, while lateral drop landing resulted in longer ML TTS relative to both forward jumps (p < 0.001). These results demonstrate that the TTS and BBS stability indexes should be used as distinct measures of dynamic postural stability. TTS protocols may be modified to target a specific training conditions or athletic population.

Assessment of postural stability using inertial measurement unit on inclined surfaces in healthy adults - biomed 2013.

PubMed

Frames, Chris; Soangra, Rahul; Lockhart, Thurmon E

2013-01-01

Fatal and nonfatal falls in the construction domain remain a significant issue in today’s workforce. The roofing industry in particular, annually ranks amongst the highest in all industries. Exposure to an inclined surface, such as an inclined roof surface, has been reported to have adverse effects on postural stability. The purpose of this preliminary study was to investigate the intra-individual differences in stability parameters on both inclined and level surfaces. Postural Stability (PS) and Limit of Stability (LOS) were assessed in seven healthy subjects (aged 25-35 years) on inclined and level surfaces using embedded force plates and an Inertial Measurement Unit (IMU). Four 90-second trials were collected on the inclined surface in distinctive positions: (1) Toes raised 20o above heel; (2) Heels raised 20o above toes (3); Transverse direction with dominant foot inverted at a lower height; (4) Transverse direction with non-dominant foot inverted at a lower height. Limit of Stability was evaluated by the two measurement devices in all four directions and margin of safety was quantified for each individual on both surfaces. The results reveal significant differences in postural stability between the flat surface condition and the inclined surface condition when subject was positioned perpendicular to the surface slope with one foot descended below the other; specifically, a significant increase was identified when visual support was interrupted. The findings lend support to the literature and will assist in future research regarding early detection of postural imbalance and preventative measures to reduce fall risks in professions where workers are consistently exposed to inclined surfaces.

Assessment of Postural Stability using Inertial Measurement Unit on Inclined Surfaces in Healthy Adults

PubMed Central

Frames, Chris; Soangra, Rahul; Lockhart, Thurmon E.

2013-01-01

Fatal and nonfatal falls in the construction domain remain a significant issue in today’s workforce. The roofing industry in particular, annually ranks amongst the highest in all industries. Exposure to an inclined surface, such as an inclined roof surface, has been reported to have adverse effects on postural stability. The purpose of this preliminary study was to investigate the intra-individual differences in stability parameters on both inclined and level surfaces. Postural Stability (PS) and Limit of Stability (LOS) were assessed in seven healthy subjects (aged 25-35 years) on inclined and level surfaces using embedded force plates and an Inertial Measurement Unit (IMU). Four 90-second trials were collected on the inclined surface in distinctive positions: (1) Toes raised 20° above heel; (2) Heels raised 20° above toes (3); Transverse direction with dominant foot inverted at a lower height; (4) Transverse direction with non-dominant foot inverted at a lower height. Limit of Stability was evaluated by the two measurement devices in all four directions and margin of safety was quantified for each individual on both surfaces. The results reveal significant differences in postural stability between the flat surface condition and the inclined surface condition when subject was positioned perpendicular to the surface slope with one foot descended below the other; specifically, a significant increase was identified when visual support was interrupted. The findings lend support to the literature and will assist in future research regarding early detection of postural imbalance and preventative measures to reduce fall risks in professions where workers are consistently exposed to inclined surfaces. PMID:23686205

Footwear for the neuropathic patient: offloading and stability.

PubMed

van Deursen, Robert

2008-01-01

Diabetic neuropathy is related to plantar ulceration through a variety of factors of which increased plantar pressures and loss of protective sensation are the most important. Loss of sensation in the lower limbs is also related to postural instability and an increased risk of falling. Ankle and foot proprioception play an important role in postural control and this sensory function is also affected by neuropathy. It is conceivable that footwear, orthotics, casts and braces used for treatment or prevention of plantar ulceration through offloading of the injured or at-risk foot area can exacerbate the postural instability and risk of falling. This has, however, received very limited attention in the literature. There are studies that have demonstrated that footwear adjustments can influence balance and stability in healthy, elderly subjects. The adjustments made to footwear for the diabetic foot are generally more dramatic and, therefore, are expected to have a greater influence on postural stability. Furthermore, casts and braces tend to deviate even more from normal footwear. This may seriously interfere with normal gait and posture and, therefore, stability. So far the evidence suggests that patients wearing such devices demonstrate markedly reduced activity levels. This reduced activity could add to the effect of offloading. This could also be interpreted to indicate problems with stability. This presentation will review the different types of offloading interventions frequently used for ulcer treatment and prevention and will consider the mechanical effect of these interventions on stability.

Experimental muscle pain challenges the postural stability during quiet stance and unexpected posture perturbation.

PubMed

Hirata, Rogério Pessoto; Ervilha, Ulysses Fernandes; Arendt-Nielsen, Lars; Graven-Nielsen, Thomas

2011-08-01

Musculoskeletal pain impairs postural control and stability. Nine subjects stood as quietly as possible on a moveable force platform before, during, and after experimental pain in the right leg muscles. A moveable force platform was used to measure the center of pressure and provided unexpected perturbations. Lower limb muscle activity, joint angles, and foot pressure distributions were measured. Hypertonic saline was used to induce pain in the vastus lateralis, vastus medialis, or biceps femoris muscle of the right leg. Compared to baseline and control sessions, pain in the knee extensor muscles during quiet standing evoked: 1) larger sway area, greater medial-lateral center of pressure displacement and higher speed (P < .05); 2) increased sway displacement in the anterior-posterior direction (P < .05); and 3) increased electromyography (EMG) activity for left tibialis anterior and left erector spinae muscles (P < .05). Pain provoked longer time to return to an equilibrium posture after forward EMG activity for, and pain in vastus medialis muscle decreased the time for the maximum hip flexion during this perturbation (P < .05). These results show that muscle pain impairs postural stability during quiet standing and after unexpected perturbation, which suggest that people suffering from leg muscle pain are more vulnerable to falls. This article presents the acute responses to leg muscle pain on the postural control. This measure could potentially help clinicians who seek to assess how pain responses may contribute to patient's postural control and stability during quiet standing and after recovering from unexpected perturbations. Copyright © 2011 American Pain Society. Published by Elsevier Inc. All rights reserved.

The visual control of stability in children and adults: postural readjustments in a ground optical flow.

PubMed

Baumberger, Bernard; Isableu, Brice; Flückiger, Michelangelo

2004-11-01

The aim of this research was to analyse the development of postural reactions to approaching (AOF) and receding (ROF) ground rectilinear optical flows. Optical flows were shaped by a pattern of circular spots of light projected on the ground surface by a texture flow generator. The geometrical structure of the projected scenes corresponded to the spatial organisation of visual flows encountered in open outdoor settings. Postural readjustments of 56 children, ranging from 7 to 11 years old, and 12 adults were recorded by the changes of the centre of foot pressure (CoP) on a force platform during 44-s exposures to the moving texture. Before and after the optical flows exposure, a 24-s motionless texture served as a reference condition. Effect of ground rectilinear optical flows on postural control development was assessed by analysing sway latencies (SL), stability performances and postural orientation. The main results that emerge from this experiment show that postural responses are directionally specific to optical flow pattern and that they vary as a function of the motion onset and offset. Results showed that greater developmental changes in postural control occurred in an AOF (both at the onset and offset of the optical flow) than in an ROF. Onset of an approaching flow induced postural instability, canonical shifts in postural orientation and long latencies in children which were stronger than in the receding flow. This pattern of responses evolved with age towards an improvement in stability performances and shorter SL. The backward decreasing shift of the CoP in children evolved in adults towards forward postural tilt, i.show $132#e. in the opposite direction of the texture's motion. Offset of an AOF motion induced very short SL in children (which became longer in adult subjects), strong postural instability, but weaker shift of orientation compared to the receding one. Postural stability improved and orientation shift evolved to forward inclinations with age. SL remained almost constant across age at both onset and offset of the receding flow. Critical developmental periods seem to occur by the age of 8 and 10 years, as suggested by the transient 'neglect' of the children to optical flows. Linear vection was felt by 90% of the 7 year olds and decreased with age to reach 55% in adult subjects. The mature sensorimotor coordination subserving the postural organisation shown in adult subjects is an example aiming at reducing the postural effects induced by optical flows. The data are discussed in relation to the perceptual importance of mobile visual references on a ground support.

Effects of reduced plantar cutaneous sensation on static postural control in individuals with and without chronic ankle instability.

PubMed

Song, Kyeongtak; Kang, Tae Kyu; Wikstrom, Erik A; Jun, Hyung-Pil; Lee, Sae Yong

2017-10-01

The purpose of this study was to determine how reduced plantar cutaneous sensation influences static postural control in individuals with and without CAI. A case-control study design. Twenty-six individuals with self-reported CAI and 26 matched healthy controls participated in this study. The plantar aspect of the participants' foot was then submersed in ice water (0°C) for 10min to reduce plantar sensation. Before and after the cooling procedure, plantar cutaneous sensation thresholds and single leg balance with eyes open and closed were assessed. Significantly, higher scores were observed in both groups after ice water submersion (p<0.001) indicating a significant reduction in the plantar cutaneous sensitivity after the cooling procedure. In single limb balance with eyes open, there were significant intervention main effects for the TTB ML mean (p<0.001), TTB AP mean (p=0.035) and TTB ML SD (p=0.021); indicating postural control improvement in both groups post-cooling. In single limb balance with eyes closed, Group×Intervention interactions were observed for the TTB AP mean (p=0.003) and TTB AP SD (p=0.017); indicating postural control deficits in CAI group post-cooling, but no changes in the control group. The main finding of this study was that reduced plantar cutaneous sensation induced by an ice submersion procedure caused eyes closed postural control impairments in those with CAI but not healthy controls. The present investigation demonstrated that the ability to dynamically reweight among sensory inputs to maintain postural stability appears to be diminished in CAI patients compared to healthy controls. Copyright © 2016. Published by Elsevier Ltd.

Locomotor sensory organization test: a novel paradigm for the assessment of sensory contributions in gait.

PubMed

Chien, Jung Hung; Eikema, Diderik-Jan Anthony; Mukherjee, Mukul; Stergiou, Nicholas

2014-12-01

Feedback based balance control requires the integration of visual, proprioceptive and vestibular input to detect the body's movement within the environment. When the accuracy of sensory signals is compromised, the system reorganizes the relative contributions through a process of sensory recalibration, for upright postural stability to be maintained. Whereas this process has been studied extensively in standing using the Sensory Organization Test (SOT), less is known about these processes in more dynamic tasks such as locomotion. In the present study, ten healthy young adults performed the six conditions of the traditional SOT to quantify standing postural control when exposed to sensory conflict. The same subjects performed these six conditions using a novel experimental paradigm, the Locomotor SOT (LSOT), to study dynamic postural control during walking under similar types of sensory conflict. To quantify postural control during walking, the net Center of Pressure sway variability was used. This corresponds to the Performance Index of the center of pressure trajectory, which is used to quantify postural control during standing. Our results indicate that dynamic balance control during locomotion in healthy individuals is affected by the systematic manipulation of multisensory inputs. The sway variability patterns observed during locomotion reflect similar balance performance with standing posture, indicating that similar feedback processes may be involved. However, the contribution of visual input is significantly increased during locomotion, compared to standing in similar sensory conflict conditions. The increased visual gain in the LSOT conditions reflects the importance of visual input for the control of locomotion. Since balance perturbations tend to occur in dynamic tasks and in response to environmental constraints not present during the SOT, the LSOT may provide additional information for clinical evaluation on healthy and deficient sensory processing.

Dynamic Postural-Stability Deficits After Cryotherapy to the Ankle Joint.

PubMed

Fullam, Karl; Caulfield, Brian; Coughlan, Garrett F; McGroarty, Mark; Delahunt, Eamonn

2015-09-01

Decreased postural stability is a primary risk factor for lower limb musculoskeletal injuries. During athletic competitions, cryotherapy may be applied during short breaks in play or during half-time; however, its effects on postural stability remain unclear. To investigate the acute effects of a 15-minute ankle-joint cryotherapy application on dynamic postural stability. Controlled laboratory study. University biomechanics laboratory. A total of 29 elite-level collegiate male field-sport athletes (age = 20.8 ± 1.12 years, height = 1.80 ± 0.06 m, mass = 81.89 ± 8.59 kg) participated. Participants were tested on the anterior (ANT), posterolateral (PL), and posteromedial (PM) reach directions of the Star Excursion Balance Test before and after a 15-minute ankle-joint cryotherapy application. Normalized reach distances; sagittal-plane kinematics of the hip, knee, and ankle joints; and associated mean velocity of the center-of-pressure path during performance of the ANT, PL, and PM reach directions of the Star Excursion Balance Test. We observed a decrease in reach-distance scores for the ANT, PL, and PM reach directions from precryotherapy to postcryotherapy (P < .05). No differences were observed in hip-, knee-, or ankle-joint sagittal-plane kinematics (P > .05). We noted a decrease in mean velocity of the center-of-pressure path from precryotherapy to postcryotherapy (P < .05) in all reach directions. Dynamic postural stability was adversely affected immediately after cryotherapy to the ankle joint.

9 CFR 3.80 - Primary enclosures.

Code of Federal Regulations, 2010 CFR

2010-01-01

... injuring themselves; and (xi) Provide sufficient space for the nonhuman primates to make normal postural... maintained so as to provide sufficient space to allow each nonhuman primate to make normal postural... postural adjustments and movements within the primary enclosure. Different species of prosimians vary in...

Back posture education in elementary schoolchildren: a 2-year follow-up study.

PubMed

Geldhof, Elisabeth; Cardon, Greet; De Bourdeaudhuij, Ilse; De Clercq, Dirk

2007-06-01

Within the scope of primary prevention regarding back functioning in children, research on the stability of intervention effects is indispensable. Along this line, the transition from childhood to adolescence is an important phase to evaluate the potential stability of intervention effects because of the typically mechanical and psychological demands related to adolescence. The main aim of the current study was to investigate the effects of a back education program at 2-year follow-up, in youngsters aged 13-14 years, on back posture knowledge, fear-avoidance beliefs and self-reported pain. An additional purpose was to evaluate which aspects of postural behavior were integrated in youngsters' lifestyles. At 2-year follow-up, the study sample included 94 secondary schoolchildren in the intervention group (mean age 13.3 +/- 0.8 years) and 101 controls (mean age 13.2 +/- 0.7 years). The back posture program that had been implemented for two school years consisted of back education and the stimulation of postural dynamism in the class through support and environmental changes. A questionnaire was completed comparable to the pretest, posttest and follow-up evaluations. The current study demonstrated at 2-year follow-up stability of the improved general (F = 1.590, ns) and specific (F = 0.049, ns) back posture knowledge in children who had received early back posture education. Back posture education did not result in increased fear-avoidance beliefs (F = 1.163, ns) or mounting back and/or neck pain reports (F = 0.001, ns). Based on self-reports for postural behavior, youngsters who had received the back posture program in the elementary school curriculum integrated crucial sitting and lifting principles conform to biomechanical favorable postural behavior. The steady intervention effects 2-year post-intervention demonstrated that intensive back posture education through the elementary school curriculum is effective till adolescence. Future research on the impact of early school-based back posture promotion in relation to the integration of back posture principles according to a biomechanical favorable lifestyle and back pain prevalence later in life is essential.

Back posture education in elementary schoolchildren: a 2-year follow-up study

PubMed Central

Geldhof, Elisabeth; De Bourdeaudhuij, Ilse; De Clercq, Dirk

2006-01-01

Within the scope of primary prevention regarding back functioning in children, research on the stability of intervention effects is indispensable. Along this line, the transition from childhood to adolescence is an important phase to evaluate the potential stability of intervention effects because of the typically mechanical and psychological demands related to adolescence. The main aim of the current study was to investigate the effects of a back education program at 2-year follow-up, in youngsters aged 13–14 years, on back posture knowledge, fear-avoidance beliefs and self-reported pain. An additional purpose was to evaluate which aspects of postural behavior were integrated in youngsters’ lifestyles. At 2-year follow-up, the study sample included 94 secondary schoolchildren in the intervention group (mean age 13.3 ± 0.8 years) and 101 controls (mean age 13.2 ± 0.7 years). The back posture program that had been implemented for two school years consisted of back education and the stimulation of postural dynamism in the class through support and environmental changes. A questionnaire was completed comparable to the pretest, posttest and follow-up evaluations. The current study demonstrated at 2-year follow-up stability of the improved general (F = 1.590, ns) and specific (F = 0.049, ns) back posture knowledge in children who had received early back posture education. Back posture education did not result in increased fear-avoidance beliefs (F = 1.163, ns) or mounting back and/or neck pain reports (F = 0.001, ns). Based on self-reports for postural behavior, youngsters who had received the back posture program in the elementary school curriculum integrated crucial sitting and lifting principles conform to biomechanical favorable postural behavior. The steady intervention effects 2-year post-intervention demonstrated that intensive back posture education through the elementary school curriculum is effective till adolescence. Future research on the impact of early school-based back posture promotion in relation to the integration of back posture principles according to a biomechanical favorable lifestyle and back pain prevalence later in life is essential. PMID:17013655

[The improvement of the abilities to maintain motor coordination and equilibrium in the students presenting with the functional disorders of the musculoskeletal system by introducing the elements of therapeutic physical training into the structure of academic schedule of physical education].

PubMed

Kapilevich, L V; Davlet'yarova, K V; Ovchinnikova, N A

The problem of deterioration of the health status in the university students at present remains as topical as it was before being a major cause of impaired working capacity, disability and/or poor social adaptation of the large number of graduates. It has been proposed to introduce a class of therapeutic physical training (TPT) into the schedule of physical education for the students. The objective of the present study was to evaluate the effectiveness of the formation of the skills needed to maintain motor coordination and equilibrium in the students presenting with the functional disorders of the musculoskeletal system (MSS) including scoliosis by the introduction of the elements of therapeutic physical training into their academic schedules. The main study group was comprised of 32 students (men) at the age of 18-19 years presenting with the disorders of the musculoskeletal system (type III scoliosis, osteochondropathy, and osteochondrosis). The students of this group received a curriculum aimed at improving their motor skills with the emphasis laid on the selected elements of therapeutic physical training. The control group was composed of 17 students without disorders of the musculoskeletal system who attended the physical education classes following the traditional program. The coordination abilities and balance skills were evaluated based on the analysis with the use of the Stabilan-1 stabilographic apparatus. In addition, the stability test and the Romberg test with open and closed eyes were performed. The results of the study give evidence that the introduction of the elements of therapeutic physical training into the structure of academic schedule of physical education for the students suffering from diseases of the musculoskeletal system has beneficial effect on the parameters of stability and the general ability to maintain the posture and balance. Specifically, in the beginning of the academic year, the students of the main study group presenting with the locomotor problems (the scatter of the manifest disorders in the frontal and sagittal planes, the mean amplitude and velocity of fluctuations of the center of pressure, the area of the projection of the center of pressure displacements as well as the quality of the equilibrium function that characterizes the ability to maintain the posture) were significantly different from the respective characteristics in the control group (p<0,05). After the course of therapeutic physical training given during the academic year, the scatter of the manifestations in the frontal and sagittal planes as well as the role of the visual control in the maintenance of balance decreased significantly. The present study has demonstrated that the introduction of the elements of therapeutic physical training into the structure of academic schedule of physical education for the students presenting with the functional disorders of the locomotor apparatus exerts the positive influence on the parameters characterizing stability and the ability to maintain the posture as well as equilibrium at large. Such beneficial effect is apparent in the form of reduction of the amplitude and velocity of fluctuations of the centre of pressure, the decrease in the area of projection of its displacements, and the improvement of the quality of the equilibrium function that characterizes the ability to maintain the posture. Moreover, the ratio of spreading in the frontal and sagittal planes decreases, and the role of the visual control in the maintenance of equilibrium becomes diminished. The results of the study give grounds for recommending the introduction of the elements of therapeutic physical training into the learning process of students presenting with diseases of the musculoskeletal system.

The influence of unilateral saccular impairment on functional balance performance and self-report dizziness.

PubMed

McCaslin, Devin L; Jacobson, Gary P; Grantham, Sarah L; Piker, Erin G; Verghese, Susha

2011-09-01

Postural stability in humans is largely maintained by vestibular, visual, and somatosensory inputs to the central nervous system. Recent clinical advances in the assessment of otolith function (e.g., cervical and ocular vestibular evoked myogenic potentials [cVEMPs and oVEMPs], subjective visual vertical [SVV] during eccentric rotation) have enabled investigators to identify patients with unilateral otolith impairments. This research has suggested that patients with unilateral otolith impairments perform worse than normal healthy controls on measures of postural stability. It is not yet known if patients with unilateral impairments of the saccule and/or inferior vestibular nerve (i.e., unilaterally abnormal cVEMP) perform differently on measures of postural stability than patients with unilateral impairments of the horizontal SCC (semicircular canal) and/or superior vestibular nerve (i.e., unilateral caloric weakness). Further, it is not known what relationship exists, if any, between otolith system impairment and self-report dizziness handicap. The purpose of this investigation was to determine the extent to which saccular impairments (defined by a unilaterally absent cVEMP) and impairments of the horizontal semicircular canal (as measured by the results of caloric testing) affect vestibulospinal function as measured through the Sensory Organization Test (SOT) of the computerized dynamic posturography (CDP). A secondary objective of this investigation was to measure the effects, if any, that saccular impairment has on a modality-specific measure of health-related quality of life. A retrospective cohort study. Subjects were assigned to one of four groups based on results from balance function testing: Group 1 (abnormal cVEMP response only), Group 2 (abnormal caloric response only), Group 3 (abnormal cVEMP and abnormal caloric response), and Group 4 (normal control group). Subjects were 92 adult patients: 62 were seen for balance function testing due to complaints of dizziness, vertigo, or unsteadiness, and 30 served as controls. All subjects underwent videonystagmography or electronystagmography (VNG/ENG), vestibular evoked myogenic potentials (VEMPs), self-report measures of self-perceived dizziness disability/handicap (Dizziness Handicap Inventory), and tests of postural control (Neurocom Equitest). Subjects were categorized into one of four groups based on balance function test results. All variables were subjected to a multifactor analysis of variance (ANOVA). The Dizziness Handicap Inventory (DHI) total scores and equilibrium scores served as the dependent variables. Results showed that patients with abnormal unilateral saccular or inferior vestibular nerve function (i.e., abnormal cVEMP) demonstrated significantly impaired postural control when compared to normal participants. However, this group demonstrated significantly better postural stability when compared to the group with abnormal caloric responses alone and the group with abnormal caloric responses and abnormal cVEMP results. Patients with an abnormal cVEMP did not differ significantly on the DHI compared to the other two impaired groups. We interpret these findings as evidence that a significantly asymmetrical cVEMP in isolation negatively impacts performance on measures of postural control compared to normal subjects but not compared to patients with significant caloric weaknesses. However, patients with a unilaterally abnormal cVEMP do not differ from patients with significant caloric weaknesses in regard to self-perceived dizziness handicap. American Academy of Audiology.

Locomotor Sensory Organization Test: How Sensory Conflict Affects the Temporal Structure of Sway Variability During Gait.

PubMed

Chien, Jung Hung; Mukherjee, Mukul; Siu, Ka-Chun; Stergiou, Nicholas

2016-05-01

When maintaining postural stability temporally under increased sensory conflict, a more rigid response is used where the available degrees of freedom are essentially frozen. The current study investigated if such a strategy is also utilized during more dynamic situations of postural control as is the case with walking. This study attempted to answer this question by using the Locomotor Sensory Organization Test (LSOT). This apparatus incorporates SOT inspired perturbations of the visual and the somatosensory system. Ten healthy young adults performed the six conditions of the traditional SOT and the corresponding six conditions on the LSOT. The temporal structure of sway variability was evaluated from all conditions. The results showed that in the anterior posterior direction somatosensory input is crucial for postural control for both walking and standing; visual input also had an effect but was not as prominent as the somatosensory input. In the medial lateral direction and with respect to walking, visual input has a much larger effect than somatosensory input. This is possibly due to the added contributions by peripheral vision during walking; in standing such contributions may not be as significant for postural control. In sum, as sensory conflict increases more rigid and regular sway patterns are found during standing confirming the previous results presented in the literature, however the opposite was the case with walking where more exploratory and adaptive movement patterns are present.

Continuous cognitive task promotes greater postural stability than an internal or external focus of attention.

PubMed

Polskaia, Nadia; Richer, Natalie; Dionne, Eliane; Lajoie, Yves

2015-02-01

Research has demonstrated clear advantages of using an external focus of attention in postural control tasks, presumably since it allows a more automatic control of posture to emerge. However, the influence of cognitive tasks on postural stability has produced discordant results. This study aimed to compare the effects of an internal focus of attention, an external focus of attention and a continuous cognitive task on postural control. Twenty healthy participants (21.4±2.6 years) were recruited for this study. They were asked to stand quietly on a force platform with their feet together in three different attentional focus conditions: an internal focus condition (minimizing movements of the hips), an external focus condition (minimizing movements of markers placed on the hips) and a cognitive task condition (silently counting the total number of times a single digit was verbalized in a 3-digit sequence comprised of 30 numbers). Results demonstrated improved stability while performing the cognitive task as opposed to the internal and external focus conditions, as evidenced by a reduction in sway area, sway variability in the anterior-posterior (AP) and medial-lateral (ML) directions, and mean velocity (ML only). Results suggest that the use of a continuous cognitive task permits attention to be withdrawn from the postural task, thereby facilitating a more automatic control of posture. Copyright © 2014 Elsevier B.V. All rights reserved.

Stabilization of posture by precision touch of the index finger with rigid and flexible filaments

NASA Technical Reports Server (NTRS)

Lackner, J. R.; Rabin, E.; DiZio, P.

2001-01-01

Light touch of the index finger with a stationary surface at non-mechanically supportive force levels (<100 g) greatly attenuates the body sway of standing subjects. In three experiments, we evaluated the properties of finger contact and of the contacted object necessary to produce postural stabilization in subjects standing heel-to-toe with eyes closed, as well as how accurately hand position can be controlled. Experiment 1 involved finger contact with flexible filaments of different bending strengths, a flat surface, and an imagined spatial position. Contact with the flat surface was most effective in attenuating sway; the flexible filaments were much less effective but still significantly better than imagined contact. Experiment 2 compared the effectiveness of finger contact with a flexible filament, a rigid filament of the same diameter, a flat surface, and an imagined spatial position. The rigid filament and flat surface conditions were equally effective in attenuating body sway and were greatly superior to contact with the flexible filament, which was superior to imagined contact. Experiment 3 included five conditions: arms by sides; finger "contact" with an imagined spatial position; finger contact with a flat surface; finger contact with a flexible filament attempting to maintain it bent; and contact with the flexible filament attempting not to bend it. The arms by sides and finger "contact" with an imagined position conditions did not differ significantly; all three conditions involving actual finger contact showed significantly less center of pressure and hand sway, but contact with the flat surface was most effective in attenuating both postural and hand displacement. In all three experiments, the level of force applied in fingertip contact conditions was far below that necessary to provide mechanical stabilization. Our findings indicate that: (1) stimulation of a small number of receptors in the fingertip is adequate to allow stabilization of sway, (2) fingertip force levels as low as 5-10 g provide some stabilization, (3) contact with a stationary spatial referent is most effective, and (4) independent control of arm and torso occurs when finger contact is allowed.

Control of mediolateral stability during rapid step initiation with preferred and non-preferred leg: is it symmetrical?

PubMed

Yiou, E; Do, M C

2010-05-01

During voluntary stepping initiation, postural stability along the mediolateral direction is controlled via "anticipatory postural adjustment" (APA). This study tested the hypothesis that, in young healthy subjects, the biomechanical features of mediolateral APA depend on the leg that initiates stepping. Subjects (N=10) initiated a rapid single step with the preferred (P condition) and the non-preferred leg (NP condition) on a force-plate. Results showed that mediolateral APA duration (P=0.020) and amplitude were higher (as attested by the increase in maximal center-of-gravity velocity (P=0.003) and displacement (P<0.001) during APA), and that mediolateral stability was better (as attested by the attenuation in center-of-gravity velocity at time of swing-foot contact (P=0.007)) in P than in NP. These results support the view that stepping initiation in healthy subjects involves postural asymmetry. This statement may have relevant implications in clinical evaluation where postural asymmetry is generally considered as reflecting postural impairment. Copyright 2010 Elsevier B.V. All rights reserved.

Stability analysis via the concept of Lyapunov exponents: a case study in optimal controlled biped standing

NASA Astrophysics Data System (ADS)

Sun, Yuming; Wu, Christine Qiong

2012-12-01

Balancing control is important for biped standing. In spite of large efforts, it is very difficult to design balancing control strategies satisfying three requirements simultaneously: maintaining postural stability, improving energy efficiency and satisfying the constraints between the biped feet and the ground. In this article, a proportional-derivative (PD) controller is proposed for a standing biped, which is simplified as a two-link inverted pendulum with one additional rigid foot-link. The genetic algorithm (GA) is used to search for the control gain meeting all three requirements. The stability analysis of such a deterministic biped control system is carried out using the concept of Lyapunov exponents (LEs), based on which, the system stability, where the disturbance comes from the initial states, and the structural stability, where the disturbance comes from the PD gains, are examined quantitively in terms of stability region. This article contributes to the biped balancing control, more significantly, the method shown in the studied case of biped provides a general framework of systematic stability analysis for certain deterministic nonlinear dynamical systems.

Salivary α-amylase reflects change in attentional demands during postural control: comparison with probe reaction time.

PubMed

Akizuki, Kazunori; Ohashi, Yukari

2014-12-01

The influence of attention on postural control and the relationship between attention and falling has been reported in previous studies. Although a dual-task procedure is commonly used to measure attentional demand, such procedures are affected by allocation policy, which is a mental strategy to divide attention between simultaneous tasks. Therefore, we examined the effectiveness of salivary α-amylase, which is a physiological method for measuring attentional demand during postural control. Sixteen healthy participants performed a postural-control task using the Balance System, which is a device that can be calibrated to a specific stability level ("Level 1 = least stable" to "Level 8 = most stable"). Levels 1, 2, and 3 were used for this study. Dependent variables measured were overall stability index, which represents the variance of platform displacement in degrees from a horizontal plane; probe reaction time, which was measured using a sound stimulator and recorder; and salivary α-amylase, which was measured using a portable salivary amylase analyzer. As stability level of the test task decreased, both stability index and probe reaction time significantly increased. In addition, we identified a positive moderate correlation between probe reaction time and salivary α-amylase. Our results suggest that salivary α-amylase and probe reaction time reflect the change in attentional demands during a postural-control task and that salivary α-amylase may be an effective tool for evaluating attentional demands during postural control because it is noninvasive and simple to perform.

Dopaminergic modulation of multi-muscle synergies in postural tasks performed by patients with Parkinson’s disease

PubMed Central

Falaki, Ali; Huang, Xuemei; Lewis, Mechelle M.; Latash, Mark L.

2017-01-01

Background Postural instability is one of most disabling motor symptoms in Parkinson’s disease. Indices of multi-muscle synergies are new measurements of postural stability. Objectives We explored the effects of dopamine-replacement drugs on multi-muscle synergies stabilizing center of pressure coordinate and their adjustments prior to a self-triggered perturbation in patients with Parkinson’s disease. We hypothesized that both synergy indices and synergy adjustments would be improved on dopaminergic drugs. Methods Patients at Hoehn-Yahr stages II and III performed whole-body tasks both off- and on-drugs while standing. Muscle modes were identified as factors in the muscle activation space. Synergy indices stabilizing center of pressure in the anterior-posterior direction were quantified in the muscle mode space during a load-release task. Results Dopamine-replacement drugs led to more consistent organization of muscles in stable groups (muscle modes). On-drugs patients showed larger indices of synergies and anticipatory synergy adjustments. In contrast, no medication effects were seen on anticipatory postural adjustments or other performance indices. Conclusions Dopamine-replacement drugs lead to significant changes in characteristics of multi-muscle synergies in Parkinson’s disease. Studies of synergies may provide a biomarker sensitive to problems with postural stability and agility and to efficacy of dopamine-replacement therapy. PMID:28110044

[Effects of Surgically Treated Pelvic Ring and Acetabular Fractures on Postural Control].

PubMed

Lang, P; Schnegelberger, A; Riesner, H-J; Stuby, F; Friemert, B; Palm, H-G

2016-04-01

The aim of surgical treatment of pelvic ring and acetabular fractures is to allow rapid mobilisation of patients in order to restore stance and gait stability (postural control), as this significantly correlates with a positive outcome. The regulation of postural stability is mainly controlled by transmission of proprioceptive stimuli. In addition, the pelvis serves as a connection between the legs and the spine and thus is also of great importance for mechanical stabilisation. It remains unclear whether surgical treatment of pelvic ring and acetabular fractures affects the regulation of postural control. Therefore, the aim of this study was to examine the impact of surgically treated pelvic ring and acetabular fractures on postural stability by means of computerised dynamic posturography (CDP) after a mean of 35 months and to compare the results with a healthy control group. A retrospective case control study of 38 patients with surgically treated pelvic ring and acetabular fractures and 38 healthy volunteers was carried out using CDP. The average time of follow-up was 35 (12-78) months. The most important outcome parameter in this investigation was the overall stability index (OSI). Hip joint mobility, the health-related quality of life (SF-12) and pain were supplementary outcome parameters. It was found that surgically treated pelvic ring and acetabular fractures had no influence on postural stability. The OSI was 2.1 ° in the patient group and 1.9 ° in the control group. There was no significant difference between the groups in hip joint mobility. A total of 52 % of patients showed no or only mild pain. Mean health-related quality of life was the same as in the total population. Surgically treated pelvic ring and acetabular fractures do not lead to deterioration in postural control in the mid term. This is of high prognostic importance for rapid mobilisation of the patients. Therefore no increase in the risk of falling is expected after successfully treatment of fractures. Georg Thieme Verlag KG Stuttgart · New York.

Assessment of postural control in patients with Parkinson's disease: sway ratio analysis.

PubMed

Błaszczyk, Janusz W; Orawiec, Renata

2011-04-01

Analysis of the postural stability impairments in neurodegenerative diseases is a very demanding task. Age-related declines in posturographic indices are usually superimposed on effects associated with the pathology and its treatment. We present the results of a novel postural sway ratio (SR) analysis in patients with Parkinson's disease (PD) and age-matched healthy subjects. The sway ratios have been assessed based upon center of foot-pressure (CP) signals recorded in 55 parkinsonians (Hoehn and Yahr: 1-3) and 55 age-matched healthy volunteers while standing quiet with eyes open (EO) and then with eyes closed (EC). Complementing classical sway measure abnormalities, the SR exhibited a high discriminative power for all controlled factors: pathology, vision, and direction of sway. Both the anteroposterior (AP) and mediolateral (ML) sway ratios were significantly increased in PD patients when compared to the control group. An additional SR increase was observed in the response to eyes closure. The sway ratio changes documented here can be attributed to a progressive decline of a postural stability control due to pathology. In fact, a significant correlation between the mediolateral SR under EO conditions and Motor Exam (section III) score of the UPDRS was found. The mediolateral sway ratios computed for EO and EC conditions significantly correlated with the CP path length (r = .87) and the mean anteroposterior CP position within the base of support (r = .38). Both indices reflect postural stability decline and fall tendency # in parkinsonians. The tremor-type PD patients (N=34) showed more pronounced relationships between the mediolateral SR and selected items from the UPDRS scale, including: falls (Kendall Tau=.47, p < .05), rigidity (.45, p < .05), postural stability (retropulsion) (.52), and the Motor Exam score (.73). The anteroposterior SR correlated only with tremor (Kendal Tau = .77, p < .05). It seems that in force plate posturography the SR can be recommended as a single reliable measure that allows for a better quantitative assessment of postural stability impairments. Copyright © 2010 Elsevier B.V. All rights reserved.

The effect of boundary shape and minima selection on single limb stance postural stability.

PubMed

Cobb, Stephen C; Joshi, Mukta N; Bazett-Jones, David M; Earl-Boehm, Jennifer E

2012-11-01

The effect of time-to-boundary minima selection and stability limit definition was investigated during eyes open and eyes closed condition single-limb stance postural stability. Anteroposterior and mediolateral time-to-boundary were computed using the mean and standard deviation (SD) of all time-to-boundary minima during a trial, and the mean and SD of only the 10 absolute time-to-boundary minima. Time-to-boundary with rectangular, trapezoidal, and multisegmented polygon defined stability limits were also calculated. Spearman's rank correlation coefficient test results revealed significant medium-large correlations between anteroposterior and mediolateral time-to-boundary scores calculated using both the mean and SD of the 10 absolute time-to-boundary minima and of all the time-to-boundary minima. Friedman test results revealed significant mediolateral time-to-boundary differences between boundary shape definitions. Follow-up Wilcoxon signed rank test results revealed significant differences between the rectangular boundary shape and both the trapezoidal and multisegmented polygon shapes during the eyes open and eyes closed conditions when both the mean and the SD of the time-to-boundary minima were used to represent postural stability. Significant differences were also revealed between the trapezoidal and multisegmented polygon definitions during the eyes open condition when the SD of the time-to-boundary minima was used to represent postural stability. Based on these findings, the overall results (i.e., stable versus unstable participants or groups) of studies computing postural stability using different minima selection can be compared. With respect to boundary shape, the trapezoid or multisegmented polygon shapes may be more appropriate than the rectangular shape as they more closely represent the anatomical shape of the stance foot.

Postural stability and quality of life after guided and self-training among older adults residing in an institutional setting.

PubMed

Tuunainen, Eeva; Rasku, Jyrki; Jäntti, Pirkko; Moisio-Vilenius, Päivi; Mäkinen, Erja; Toppila, Esko; Pyykkö, Ilmari

2013-01-01

To evaluate whether rehabilitation of muscle force or balance improves postural stability and quality of life (QoL), and whether self-administered training is comparable with guided training among older adults residing in an institutional setting. A randomized, prospective intervention study was undertaken among 55 elderly patients. Three intervention groups were evaluated: a muscle force training group; a balance and muscle force training group; and a self-administered training group. Each group underwent 1-hour-long training sessions, twice a week, for 3 months. Postural stability was measured at onset, after 3 months, and after 6 months. Time-domain-dependent body sway variables were calculated. The fall rate was evaluated for 3 years. General health related quality of life (HRQoL) was measured with a 15D instrument. Postural stability was used as a primary outcome, with QoL and falls used as secondary outcomes. Muscle force trainees were able to undertake training, progressing towards more strenuous exercises. In posturography, the number of spiky oscillations was reduced after training, and stationary fields of torque moments of the ankle increased, providing better postural stability in all groups; in particular, the zero crossing rate of weight signal and the number of low variability episodes in the stabilogram were improved after training. While no difference was found between different training groups in posturography outcomes, a reduction of fall rate was significant in only the guided training groups. A significant part of the variability of the QoL could be explained by the posturography outcome (46%). However, the outcome of training was associated with a reduced QoL. Even moderate or severely demented residents could do exercises in five-person groups under the supervision of a physiotherapist. An improvement in postural stability was observed in all training groups, indicating that even self-administered training could be beneficial. Posturography outcome indicated that training alters the postural strategy by reducing the oscillatory fluctuations of body sway signal. However, only guided training tended to reduce falls. Short training intervention programs may decrease QoL by changing the elderly's daily routine and making it more active and exhausting.

The effect of visual-vestibulosomatosensory conflict induced by virtual reality on postural stability in humans.

PubMed

Nishiike, Suetaka; Okazaki, Suzuyo; Watanabe, Hiroshi; Akizuki, Hironori; Imai, Takao; Uno, Atsuhiko; Kitahara, Tadashi; Horii, Arata; Takeda, Noriaki; Inohara, Hidenori

2013-01-01

In this study, we examined the effects of sensory inputs of visual-vestibulosomatosensory conflict induced by virtual reality (VR) on subjective dizziness, posture stability and visual dependency on postural control in humans. Eleven healthy young volunteers were immersed in two different VR conditions. In the control condition, subjects walked voluntarily with the background images of interactive computer graphics proportionally synchronized to their walking pace. In the visual-vestibulosomatosensory conflict condition, subjects kept still, but the background images that subjects experienced in the control condition were presented. The scores of both Graybiel's and Hamilton's criteria, postural instability and Romberg ratio were measured before and after the two conditions. After immersion in the conflict condition, both subjective dizziness and objective postural instability were significantly increased, and Romberg ratio, an index of the visual dependency on postural control, was slightly decreased. These findings suggest that sensory inputs of visual-vestibulosomatosensory conflict induced by VR induced motion sickness, resulting in subjective dizziness and postural instability. They also suggest that adaptation to the conflict condition decreases the contribution of visual inputs to postural control with re-weighing of vestibulosomatosensory inputs. VR may be used as a rehabilitation tool for dizzy patients by its ability to induce sensory re-weighing of postural control.

Analysis of the postural stability in individuals with or without signs and symptoms of temporomandibular disorder.

PubMed

Ries, Lilian Gerdi Kittel; Bérzin, Fausto

2008-01-01

The objective of this study was to evaluate the stability and the distribution of weight of individuals with TMD (Temporomandibular Disorder) when placed in an orthostatic position. Forty female volunteers, participating in this study, were distributed into a control and a TMD group. Clinical examinations of the craniomandibular system and of the neck were performed. Postural stability was evaluated using a stabilographic platform. Through this system, the sway index (SI), the maximum medial-lateral distance (MMLD), the maximum anterior-posterior distance (MAPD) and the medial-lateral symmetry (MLS) could be determined. Tests were performed in the mandibular rest position and during isometric and isotonic contraction. The variables were analyzed through repeated measures ANOVA. The level of significance was p < 0.05. The results of this study indicate that individuals with TMD present more pain in the cervical region (p < 0.05). The group with TMD showed a significant reduction in SI (p < 0.05), MMLD (p < 0.05) and MLS (p < 0.01). Individuals with TMD presented greater postural asymmetry, and cervical pain demonstrated a potential link with an increase in postural stability.

Impact of soft and hard insole density on postural stability in older adults.

PubMed

Losa Iglesias, Marta Elena; Becerro de Bengoa Vallejo, Ricardo; Palacios Peña, Domingo

2012-01-01

A significant predictor of falls in the elderly population is attributed to postural instability. Thus, it is important to identify and implement practical clinical interventions to enhance postural stability in older adults. Shoe insoles have been identified as a mechanism to enhance postural control, and our study aimed to evaluate the impact of 2 shoe insoles on static standing balance in healthy, older adults compared with standing posture while barefoot. We hypothesized that both hard and soft shoe insoles would decrease postural sway compared with the barefoot condition. Indeed, excursion distances and sway areas were reduced, and sway velocity was decreased when wearing insoles. The hard insole was also effective when visual feedback was removed, suggesting that the more rigid an insole, the greater potential reduction in fall risk. Thus, shoe insoles may be a cost-effective, clinical intervention that is easy to implement to reduce the risk of falling in the elderly population. Copyright © 2012 Mosby, Inc. All rights reserved.

Effect of Postural Control Demands on Early Visual Evoked Potentials during a Subjective Visual Vertical Perception Task in Adolescents with Idiopathic Scoliosis.

PubMed

Chang, Yi-Tzu; Meng, Ling-Fu; Chang, Chun-Ju; Lai, Po-Liang; Lung, Chi-Wen; Chern, Jen-Suh

2017-01-01

Subjective visual vertical (SVV) judgment and standing stability were separately investigated among patients with adolescent idiopathic scoliosis (AIS). Although, one study has investigated the central mechanism of stability control in the AIS population, the relationships between SVV, decreased standing stability, and AIS have never been investigated. Through event-related potentials (ERPs), the present study examined the effect of postural control demands (PDs) on AIS central mechanisms related to SVV judgment and standing stability to elucidate the time-serial stability control process. Thirteen AIS subjects (AIS group) and 13 age-matched adolescents (control group) aged 12-18 years were recruited. Each subject had to complete an SVV task (i.e., the modified rod-and-frame [mRAF] test) as a stimulus, with online electroencephalogram recording being performed in the following three standing postures: feet shoulder-width apart standing, feet together standing, and tandem standing. The behavioral performance in terms of postural stability (center of pressure excursion), SVV (accuracy and reaction time), and mRAF-locked ERPs (mean amplitude and peak latency of the P1, N1, and P2 components) was then compared between the AIS and control groups. In the behavioral domain, the results revealed that only the AIS group demonstrated a significantly accelerated SVV reaction time as the PDs increased. In the cerebral domain, significantly larger P2 mean amplitudes were observed during both feet shoulder-width-apart standing and feet together standing postures compared with during tandem standing. No group differences were noted in the cerebral domain. The results indicated that (1) during the dual-task paradigm, a differential behavioral strategy of accelerated SVV reaction time was observed in the AIS group only when the PDs increased and (2) the decrease in P2 mean amplitudes with the increase in the PD levels might be direct evidence of the competition for central processing attentional resources under the dual-task postural control paradigm.

Effect of Postural Control Demands on Early Visual Evoked Potentials during a Subjective Visual Vertical Perception Task in Adolescents with Idiopathic Scoliosis

PubMed Central

Chang, Yi-Tzu; Meng, Ling-Fu; Chang, Chun-Ju; Lai, Po-Liang; Lung, Chi-Wen; Chern, Jen-Suh

2017-01-01

Subjective visual vertical (SVV) judgment and standing stability were separately investigated among patients with adolescent idiopathic scoliosis (AIS). Although, one study has investigated the central mechanism of stability control in the AIS population, the relationships between SVV, decreased standing stability, and AIS have never been investigated. Through event-related potentials (ERPs), the present study examined the effect of postural control demands (PDs) on AIS central mechanisms related to SVV judgment and standing stability to elucidate the time-serial stability control process. Thirteen AIS subjects (AIS group) and 13 age-matched adolescents (control group) aged 12–18 years were recruited. Each subject had to complete an SVV task (i.e., the modified rod-and-frame [mRAF] test) as a stimulus, with online electroencephalogram recording being performed in the following three standing postures: feet shoulder-width apart standing, feet together standing, and tandem standing. The behavioral performance in terms of postural stability (center of pressure excursion), SVV (accuracy and reaction time), and mRAF-locked ERPs (mean amplitude and peak latency of the P1, N1, and P2 components) was then compared between the AIS and control groups. In the behavioral domain, the results revealed that only the AIS group demonstrated a significantly accelerated SVV reaction time as the PDs increased. In the cerebral domain, significantly larger P2 mean amplitudes were observed during both feet shoulder-width-apart standing and feet together standing postures compared with during tandem standing. No group differences were noted in the cerebral domain. The results indicated that (1) during the dual-task paradigm, a differential behavioral strategy of accelerated SVV reaction time was observed in the AIS group only when the PDs increased and (2) the decrease in P2 mean amplitudes with the increase in the PD levels might be direct evidence of the competition for central processing attentional resources under the dual-task postural control paradigm. PMID:28713252

A Methodology for Investigating Adaptive Postural Control

NASA Technical Reports Server (NTRS)

McDonald, P. V.; Riccio, G. E.

1999-01-01

Our research on postural control and human-environment interactions provides an appropriate scientific foundation for understanding the skill of mass handling by astronauts in weightless conditions (e.g., extravehicular activity or EVA). We conducted an investigation of such skills in NASA's principal mass-handling simulator, the Precision Air-Bearing Floor, at the Johnson Space Center. We have studied skilled movement-body within a multidisciplinary context that draws on concepts and methods from biological and behavioral sciences (e.g., psychology, kinesiology and neurophysiology) as well as bioengineering. Our multidisciplinary research has led to the development of measures, for manual interactions between individuals and the substantial environment, that plausibly are observable by human sensory systems. We consider these methods to be the most important general contribution of our EVA investigation. We describe our perspective as control theoretic because it draws more on fundamental concepts about control systems in engineering than it does on working constructs from the subdisciplines of biomechanics and motor control in the bio-behavioral sciences. At the same time, we have attempted to identify the theoretical underpinnings of control-systems engineering that are most relevant to control by human beings. We believe that these underpinnings are implicit in the assumptions that cut across diverse methods in control-systems engineering, especially the various methods associated with "nonlinear control", "fuzzy control," and "adaptive control" in engineering. Our methods are based on these theoretical foundations rather than on the mathematical formalisms that are associated with particular methods in control-systems engineering. The most important aspects of the human-environment interaction in our investigation of mass handling are the functional consequences that body configuration and stability have for the pick up of information or the achievement of overt goals. It follows that an essential characteristic of postural behavior is the effective maintenance of the orientation and stability of the sensory and motor "platforms" (e.g., head or shoulders) over variations in the human, the environment and the task. This general skill suggests that individuals should be sensitive to the functional consequences of body configuration and stability. In other words, individuals should perceive the relation between configuration, stability, and performance so that they can adaptively control their interaction with the surroundings. Human-environment interactions constitute robust systems in that individuals can maintain the stability of such interactions over uncertainty about and variations in the dynamics of the interaction. Robust interactions allow individuals to adopt orientations and configurations that are not optimal with respect to purely energetic criteria. Individuals can tolerate variation in postural states, and such variation can serve an important function in adaptive systems. Postural variability generates stimulation which is "textured" by the dynamics of the human-environment system. The texture or structure in stimulation provides information about variation in dynamics, and such information can be sufficient to guide adaption in control strategies. Our method were designed to measure informative patterns of movement variability.

Effect of sitting pause times on postural stability after supine-to-standing transfer in dimly lit environments.

PubMed

Johnson, Eric G; Meltzer, Jonathan D

2012-01-01

Falls are common and often take place in the home. Risk of fall increases if the environment is dimly lit. Longer sitting pause times, before standing, might improve postural stability after standing from a supine position. The purpose of this investigation was to measure the effects of sitting pause times on postural sway velocity immediately following a supine-to-standing transfer in a dimly lit room in older and younger adult women. Five women aged 65 to 70 years and 5 aged 23 to 30 years participated in the study. On each of 2 consecutive days, study participants lay on a mat table with their eyes closed for 45 minutes before performing a supine-to-standing transfer in a dimly lit room. Sitting pause times of 2 seconds and 30 seconds preceded the transfers. Mean postural sway velocity for the whole sample and for younger and older groups was less after a 30-second pause time than that after a 2-second pause time (sample, P = .001; young, P = .019; old, P = .021). No significant difference in mean postural sway velocity was observed between the 2 groups (P > .05). Total mean postural sway velocity was less when study participants performed a sitting pause of 30 seconds before standing in a dimly lit room. These results suggest that longer sitting pause times may provide improved adaptability to dimly lit environments contributing to improved postural stability.

Vibratory noise to the fingertip enhances balance improvement associated with light touch.

PubMed

Magalhães, Fernando Henrique; Kohn, André Fabio

2011-03-01

Light touch of a fingertip on an external stable surface greatly improves the postural stability of standing subjects. The hypothesis of the present work was that a vibrating surface could increase the effectiveness of fingertip signaling to the central nervous system (e.g., by a stochastic resonance mechanism) and hence improve postural stability beyond that achieved by light touch. Subjects stood quietly over a force plate while touching with their right index fingertip a surface that could be either quiescent or randomly vibrated at two low-level noise intensities. The vibratory noise of the contact surface caused a significant decrease in postural sway, as assessed by center of pressure measures in both time and frequency domains. Complementary experiments were designed to test whether postural control improvements were associated with a stochastic resonance mechanism or whether attentional mechanisms could be contributing. A full curve relating body sway parameters and different levels of vibratory noise resulted in a U-like function, suggesting that the improvement in sway relied on a stochastic resonance mechanism. Additionally, no decrease in postural sway was observed when the vibrating contact surface was attached to the subject's body, suggesting that no attentional mechanisms were involved. These results indicate that sensory cues obtained from the fingertip need not necessarily be associated with static contact surfaces to cause improvement in postural stability. A low-level noisy vibration applied to the contact surface could lead to a better performance of the postural control system.

Influence of fear of falling on anticipatory postural control of medio-lateral stability during rapid leg flexion.

PubMed

Yiou, E; Deroche, T; Do, M C; Woodman, T

2011-04-01

During leg flexion from erect posture, postural stability is organized in advance during "anticipatory postural adjustments" (APA). During these APA, inertial forces are generated that propel the centre of gravity (CoG) laterally towards stance leg side. This study examined how fear of falling (FoF) may influence this anticipatory postural control of medio-lateral (ML) stability. Ten young healthy participants performed a series of leg flexions at maximal velocity from low and high surface heights (6 and 66 cm above ground, respectively). In this latter condition with increased FoF, stance foot was placed at the lateral edge of the support surface to induce maximal postural threat. Results showed that the amplitude of ML inertial forces generated during APA decreased with FoF; this decrease was compensated by an increase in APA duration so that the CoG position at time of swing foot-off was located further towards stance leg side. With these changes in ML APA, the CoG was propelled in the same final (unipodal) position above stance foot as in condition with low FoF. These results contrast with those obtained in the literature during quiet standing which showed that FoF did not have any influence on the ML component of postural control. It is proposed that ML APA are modified with increased FoF, in such a way that the risk of a sideway fall induced by the large CoG motion is attenuated.

Postural changes following sensory reinterpretation as an analog to spaceflight

NASA Technical Reports Server (NTRS)

Paloski, William H.; Harm, D. L.; Reschke, M. F.; Doxey, D. D.; Skinner, N. C.; Michaud, L. J.; Parker, D. E.

1990-01-01

Postural control changes noted in astronauts immediately following spaceflight are thought to be caused by inflight adaptative changes in Central Nervous System (CNS) processing of sensory information from the visual, vestibular, and proprioceptive systems. In order to elicit these adaptative changes in ground based studies, a Tilt Translation Device (TTD) which causes the CNS of exposed subjects to reinterpret tilt generated sensory inputs from the otolith organs as linear translation of the subject was developed. This device was designed to simulate partially the stimulus rearrangement experienced by astronauts during microgravity. Postural stability is assessed in ten subjects before and after 30 minutes of exposure to TTD. The resulting data suggests that exposure to TTD causes decreases in postural stability and shifts in postflight studies of astronauts. It is concluded that the TTD may be an effective weightlessness simulator, and that the postural changes following TTD exposure may provide a useful dependent measure for evaluation of this apparatus.

Pilot Study: Measuring the Effects of Center of Gravity Shift on Postural Stability

NASA Technical Reports Server (NTRS)

Times-Marshall, Chelsea; Reschke, Millard

2009-01-01

It has been shown that astronauts returning from space often experience postural instability due to the stimulus rearrangement of the visual, vestibular, and proprioceptive systems. However, postural control may also be influenced by the head-ward shift in their center of gravity (CG) that occurs as a result of the expansion of their spinal column by as much as two inches during long duration space flight, as well as the CG shift that occurs from the Life Support Pack on the extra-vehicular activity (EVA) suit. This study investigated the effect on postural stability after (1) an immediate shift in the CG towards the head, (2) a 30 minute adaptation to the shifted CG, and (3) immediate shift of the CG back to normal, accomplished by donning and removing a modified backpack. We hypothesized that at each immediate shift in CG, postural performance will be compromised.

Postural correction reduces hip pain in adult with acetabular dysplasia: A case report.

PubMed

Lewis, Cara L; Khuu, Anne; Marinko, Lee N

2015-06-01

Developmental dysplasia of the hip is often diagnosed in infancy, but less severe cases of acetabular dysplasia are being detected in young active adults. The purpose of this case report is to present a non-surgical intervention for a 31-year-old female with mild acetabular dysplasia and an anterior acetabular labral tear. The patient presented with right anterior hip and groin pain, and she stood with the trunk swayed posterior to the pelvis (swayback posture). The hip pain was reproduced with the anterior impingement test. During gait, the patient maintained the swayback posture and reported 6/10 hip pain. Following correction of the patient's posture, the patient's pain rating was reduced to a 2/10 while walking. The patient was instructed to maintain the improved posture. At the 1 year follow-up, she demonstrated significantly improved posture in standing and walking. She had returned to recreational running and was generally pain-free. The patient demonstrated improvement on self-reported questionnaires for pain, function, and activity. These findings suggest that alteration of posture can have an immediate and lasting effect on hip pain in persons with structural abnormality and labral pathology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Postural correction reduces hip pain in adult with acetabular dysplasia: a case report

PubMed Central

Lewis, Cara L.; Khuu, Anne; Marinko, Lee

2015-01-01

Developmental dysplasia of the hip is often diagnosed in infancy, but less severe cases of acetabular dysplasia are being detected in young active adults. The purpose of this case report is to present a non-surgical intervention for a 31-year-old female with mild acetabular dysplasia and an anterior acetabular labral tear. The patient presented with right anterior hip and groin pain, and she stood with the trunk swayed posterior to the pelvis (swayback posture). The hip pain was reproduced with the anterior impingement test. During gait, the patient maintained the swayback posture and reported 6/10 hip pain. Following correction of the patient’s posture, the patient’s pain rating was reduced to a 2/10 while walking. The patient was instructed to maintain the improved posture. At the 1 year follow-up, she demonstrated significantly improved posture in standing and walking. She had returned to recreational running and was generally pain-free. The patient demonstrated improvement on self-reported questionnaires for pain, function and activity. These findings suggest that alteration of posture can have an immediate and lasting effect on hip pain in persons with structural abnormality and labral pathology. PMID:25731688

An analysis of the activity and muscle fatigue of the muscles around the neck under the three most frequent postures while using a smartphone.

PubMed

Choi, Jung-Hyun; Jung, Min-Ho; Yoo, Kyung-Tae

2016-05-01

[Purpose] The purpose of this study was to identify changes in the activity and fatigue of the splenius capitis and upper trapezius muscles, which are agonists to the muscles supporting the head, under the three postures most frequently adopted while using a smartphone. [Subjects and Methods] The subjects were 15 college students in their 20s. They formed a single group and had to adopt three different postures (maximum bending, middle bending, and neutral). While the 15 subjects maintained the postures, muscle activity and fatigue were measured using surface electromyography. [Results] Comparison of the muscle fatigue caused by each posture showed statistically significant differences for the right splenius capitis, left splenius capitis, and left upper trapezius muscles. In addition, maintaining the maximum bending posture while using a smartphone resulted in higher levels of fatigue in the right splenius capitis, left splenius capitis, and left upper trapezius muscles compared with those for the middle bending posture. [Conclusion] Therefore, this study suggests that individuals should bend their neck slightly when using a smartphone, rather than bending it too much, or keep their neck straight to reduce fatigue of the cervical erector muscles.

Interactions between posture and locomotion: motor patterns in humans walking with bent posture versus erect posture.

PubMed

Grasso, R; Zago, M; Lacquaniti, F

2000-01-01

Human erect locomotion is unique among living primates. Evolution selected specific biomechanical features that make human locomotion mechanically efficient. These features are matched by the motor patterns generated in the CNS. What happens when humans walk with bent postures? Are normal motor patterns of erect locomotion maintained or completely reorganized? Five healthy volunteers walked straight and forward at different speeds in three different postures (regular, knee-flexed, and knee- and trunk-flexed) while their motion, ground reaction forces, and electromyographic (EMG) activity were recorded. The three postures imply large differences in the position of the center of body mass relative to the body segments. The elevation angles of the trunk, pelvis, and lower limb segments relative to the vertical in the sagittal plane, the ground reaction forces and the rectified EMGs were analyzed over the gait cycle. The waveforms of the elevation angles along the gait cycle remained essentially unchanged irrespective of the adopted postures. The first two harmonics of these kinematic waveforms explain >95% of their variance. The phase shift but not the amplitude ratio between the first harmonic of the elevation angle waveforms of adjacent pairs was affected systematically by changes in posture. Thigh, shank, and foot angles covaried close to a plane in all conditions, but the plane orientation was systematically different in bent versus erect locomotion. This was explained by the changes in the temporal coupling among the three segments. For walking speeds >1 m s(-1), the plane orientation of bent locomotion indicates a much lower mechanical efficiency relative to erect locomotion. Ground reaction forces differed prominently in bent versus erect posture displaying characteristics intermediate between those typical of walking and those of running. Mean EMG activity was greater in bent postures for all recorded muscles independent of the functional role. The waveforms of the muscle activities and muscle synergies also were affected by the adopted posture. We conclude that maintaining bent postures does not interfere either with the generation of segmental kinematic waveforms or with the planar constraint of intersegmental covariation. These characteristics are maintained at the expense of adjustments in kinetic parameters, muscle synergies and the temporal coupling among the oscillating body segments. We argue that an integrated control of gait and posture is made possible because these two motor functions share some common principles of spatial organization.

Recovery of short-term memory and psychomotor speed but not postural stability with long-term sobriety in alcoholic women.

PubMed

Rosenbloom, Margaret J; Pfefferbaum, Adolf; Sullivan, Edith V

2004-07-01

The authors assessed effects of extended abstinence on cognitive and motor function deficits previously observed in a group of alcoholic women (n = 43) initially tested after 15 weeks of sobriety. Alcoholic women were retested 1 and 4 years later, and control women were retested 3 years later. At Year 1, 14 of 23 returners had maintained sobriety, but they did not perform significantly better than relapsers; the group as a whole continued to show deficits relative to age norms. By Year 4, 13 of 14 returners had maintained sobriety for more than 30 months; as a group, these women had returned to normal levels on tests of memory and psychomotor speed but remained impaired in standing balance.

Sex Differences in Landing Biomechanics and Postural Stability During Adolescence: A Systematic Review with Meta-Analyses.

PubMed

Holden, Sinéad; Boreham, Colin; Delahunt, Eamonn

2016-02-01

The adolescent 'growth spurt' results in rapid growth of the skeletal system. It has been theorised that absence of a concomitant increase in muscular adaptations in female athletes may predispose them to an increased risk of anterior cruciate ligament injuries. To determine if sex differences exist in landing biomechanics and postural stability of adolescent athletes; with a further objective of determining if such differences are propagated during adolescence. The following databases were searched: MEDLINE, EMBASE, CINAHL, PEDro, PubMed, SPORTDiscus and Web of Science. Research papers were identified by including search terms for neuromuscular control, lower limb and pubertal development. Studies were required to be written in English; report on biomechanical analyses; include landing or postural control tasks; be cross-sectional or longitudinal; and include healthy adolescent/pubertal subjects. A modified version of the Strengthening the Reporting of Observational studies in Epidemiology checklist was used to rate methodological quality. Meta-analyses were performed when more than one study reported on an outcome measure. Sixteen articles were included. The overall methodological quality of evaluated studies was low (mean score = 5.75/10 points). Adolescent females exhibited increased knee valgus with increasing maturity. There was no consensus on sex differences in postural stability. With increasing maturation, females are characterized by increased knee valgus during landing tasks. To date, no research has longitudinally investigated postural stability development during adolescence in females, despite the importance of postural control training in injury prevention programmes. Therefore, further research on this topic is warranted.

The Effect of Sensory Noise Created by Compliant and Sway-Referenced Support Surfaces on Postural Stability

NASA Technical Reports Server (NTRS)

Forth, Katharine E.; Taylor, Laura C.; Paloski, William H.

2006-01-01

The purpose of the present experiment was to compare in normal human subjects the differential effects on postural stability of introducing somatosensory noise via compliant and/or sway-referenced support surfaces during quiet standing. The use of foam surfaces (two thicknesses: thin (0.95cm) and thick (7.62cm)) and sway-referenced support allowed comparison between two different types of destabilizing factors that increased ankle/foot somatosensory noise. Under some conditions neck extensions were used to increase sensory noise by deviating the vestibular system from its optimal orientation for balance control. The impact of these conditions on postural control was assessed through objective measures of instability. Thick foam and sway-referenced support conditions generated comparable instability in subjects, as measured by equilibrium score and minimum time-to-contact. However, simultaneous application of the conditions resulted in greater instability, suggesting a higher level of generated sensory noise and thus, different receptor types affected during each manipulation. Indeed, sway-referenced support generated greater anterior-posterior center-of-mass (COM) sway, while thick foam generated greater medio-lateral COM sway and velocity. Neck extension had minimal effect on postural stability until combined with simultaneous thick foam and sway-referenced support. Thin foam never generated enough sensory noise to affect postural stability even with noise added by sway-reference support or neck extension. These results provide an interesting window into the central integration of redundant sensory information and indicate the postural impact of sensory inputs is not solely based on their existence, but also their level of noise.

[Assessment of influence of breath holding and hyperventilation on human postural stability with spectral analysis of stabilographic signal].

PubMed

Malakhov, M V; Makarenkova, E A; Mel'nikov, A A; Vikulov, A D

2014-01-01

The influence of breath holding and voluntary hyperventilation on the classic stabilometric parameters and the frequency characteristic of stabilographic signal were studied. We measured the stabilometric parameters on the force platform ("Ritm", Russia) on the healthy volunteers (n = 107) during quiet breath, voluntary hyperventilation (20 seconds) and maximal inspiratory breath holding (20 seconds). Respiratory frequency, respiratory amplitude and ventilation were estimated with strain gauge. We found that antero-posterior and medio-lateral sway amplitude and velocity as well as sway surface at breath-holding and at quiet breathing were the same, so breath holding didn't influence the postural stability. However the spectral parameters shifted to the high frequency range due to alteration of the respiratory muscles contractions during breath-holding versus quiet breath. Voluntary hyperventilation caused significant increase of all stabilographic indices that implied an impairment of postural stability, which was due to the increase of respiration frequency and amplitude. We also found that the spectral indices moved toward the high-frequency range with more pronounced degree of this shift versus breath holding. Besides, amplitudes of spectral peaks also increased. Perhaps such change of spectral indices was due to distortion of proprioceptive information because of increased excitability of nerve fibers during hyperventilation. Maximal inspiration breath holding causes strain of the postural control mechanisms that is reflected as elevation of postural sway frequency with no postural stability changes. Hyperventilation leads to the most prominent strain of balance function and decrease of steadiness that is manifested as increase of center of pressure oscillations amplitude and frequency.

Anticipatory Postural Control of Stability during Gait Initiation Over Obstacles of Different Height and Distance Made Under Reaction-Time and Self-Initiated Instructions.

PubMed

Yiou, Eric; Artico, Romain; Teyssedre, Claudine A; Labaune, Ombeline; Fourcade, Paul

2016-01-01

Despite the abundant literature on obstacle crossing in humans, the question of how the central nervous system (CNS) controls postural stability during gait initiation with the goal to clear an obstacle remains unclear. Stabilizing features of gait initiation include anticipatory postural adjustments (APAs) and lateral swing foot placement. To answer the above question, 14 participants initiated gait as fast as possible in three conditions of obstacle height, three conditions of obstacle distance and one obstacle-free (control) condition. Each of these conditions was performed with two levels of temporal pressure: reaction-time (high-pressure) and self-initiated (low-pressure) movements. A mechanical model of the body falling laterally under the influence of gravity and submitted to an elastic restoring force is proposed to assess the effect of initial (foot-off) center-of-mass position and velocity (or "initial center-of-mass set") on the stability at foot-contact. Results showed that the anticipatory peak of mediolateral (ML) center-of-pressure shift, the initial ML center-of-mass velocity and the duration of the swing phase, of gait initiation increased with obstacle height, but not with obstacle distance. These results suggest that ML APAs are scaled with swing duration in order to maintain an equivalent stability across experimental conditions. This statement is strengthened by the results obtained with the mechanical model, which showed how stability would be degraded if there was no adaptation of the initial center-of-mass set to swing duration. The anteroposterior (AP) component of APAs varied also according to obstacle height and distance, but in an opposite way to the ML component. Indeed, results showed that the anticipatory peak of backward center-of-pressure shift and the initial forward center-of-mass set decreased with obstacle height, probably in order to limit the risk to trip over the obstacle, while the forward center-of-mass velocity at foot-off increased with obstacle distance, allowing a further step to be taken. These effects of obstacle height and distance were globally similar under low and high-temporal pressure. Collectively, these findings imply that the CNS is able to predict the potential instability elicited by the obstacle clearance and that it scales the spatiotemporal parameters of APAs accordingly.

Anticipatory Postural Control of Stability during Gait Initiation Over Obstacles of Different Height and Distance Made Under Reaction-Time and Self-Initiated Instructions

PubMed Central

Yiou, Eric; Artico, Romain; Teyssedre, Claudine A.; Labaune, Ombeline; Fourcade, Paul

2016-01-01

Despite the abundant literature on obstacle crossing in humans, the question of how the central nervous system (CNS) controls postural stability during gait initiation with the goal to clear an obstacle remains unclear. Stabilizing features of gait initiation include anticipatory postural adjustments (APAs) and lateral swing foot placement. To answer the above question, 14 participants initiated gait as fast as possible in three conditions of obstacle height, three conditions of obstacle distance and one obstacle-free (control) condition. Each of these conditions was performed with two levels of temporal pressure: reaction-time (high-pressure) and self-initiated (low-pressure) movements. A mechanical model of the body falling laterally under the influence of gravity and submitted to an elastic restoring force is proposed to assess the effect of initial (foot-off) center-of-mass position and velocity (or “initial center-of-mass set”) on the stability at foot-contact. Results showed that the anticipatory peak of mediolateral (ML) center-of-pressure shift, the initial ML center-of-mass velocity and the duration of the swing phase, of gait initiation increased with obstacle height, but not with obstacle distance. These results suggest that ML APAs are scaled with swing duration in order to maintain an equivalent stability across experimental conditions. This statement is strengthened by the results obtained with the mechanical model, which showed how stability would be degraded if there was no adaptation of the initial center-of-mass set to swing duration. The anteroposterior (AP) component of APAs varied also according to obstacle height and distance, but in an opposite way to the ML component. Indeed, results showed that the anticipatory peak of backward center-of-pressure shift and the initial forward center-of-mass set decreased with obstacle height, probably in order to limit the risk to trip over the obstacle, while the forward center-of-mass velocity at foot-off increased with obstacle distance, allowing a further step to be taken. These effects of obstacle height and distance were globally similar under low and high-temporal pressure. Collectively, these findings imply that the CNS is able to predict the potential instability elicited by the obstacle clearance and that it scales the spatiotemporal parameters of APAs accordingly. PMID:27656138

(De)stabilization of Required and Spontaneous Postural Dynamics with Learning

ERIC Educational Resources Information Center

Faugloire, Elise; Bardy, Benoit G.; Stoffregen, Thomas A.

2009-01-01

The present research examined how learning a new ankle-hip coordination influenced the preexisting postural repertoire. Standing participants learned a new ankle-hip coordination mode (relative phase of 90[degrees]). Before and after practice, postural patterns were evaluated in two different tasks. In the required task, specific ankle-hip…

Smartphone virtual reality to increase clinical balance assessment responsiveness.

PubMed

Rausch, Matthew; Simon, Janet E; Starkey, Chad; Grooms, Dustin R

2018-05-22

To determine if a low cost smartphone based, clinically applicable virtual reality (VR) modification to the standard Balance Error Scoring System (BESS) can challenge postural stability beyond the traditional BESS. Cross-sectional study. University research laboratory. 28 adults (mean age 23.36 ± 2.38 years, mean height 1.74 m ± 0.13, mean weight 77.95 kg ± 16.63). BESS postural control errors and center of pressure (CoP) velocity were recorded during the BESS test and a VR modified BESS (VR-BESS). The VR-BESS used a headset and phone to display a rollercoaster ride to induce a visual and vestibular challenge to postural stability. The VR-BESS significantly increased total errors (20.93 vs. 11.42, p < 0.05) and CoP velocity summed across all stances and surfaces (52.96 cm/s vs. 37.73 cm/s, p < 0.05) beyond the traditional BESS. The VR-BESS provides a standardized, and effective way to increase postural stability challenge in the clinical setting. The VR-BESS can use any smartphone technology to induce postural stability deficits that may otherwise normalize with traditional testing. Thus, providing a unique relatively inexpensive and simple to operate clinical assessment tool and∖or training stimulus. Copyright © 2018 Elsevier Ltd. All rights reserved.

The influence of peripheral neuropathy, gender, and obesity on the postural stability of patients with type 2 diabetes mellitus.

PubMed

Herrera-Rangel, Aline; Aranda-Moreno, Catalina; Mantilla-Ochoa, Teresa; Zainos-Saucedo, Lylia; Jáuregui-Renaud, Kathrine

2014-01-01

To assess the influence of peripheral neuropathy, gender, and obesity on the postural stability of patients with type 2 diabetes mellitus. 151 patients with no history of otology, neurology, or orthopaedic or balance disorders accepted to participate in the study. After a clinical interview and neuropathy assessment, postural stability was evaluated by static posturography (eyes open/closed on hard/soft surface) and the "Up & Go" test. During static posturography, on hard surface, the length of sway was related to peripheral neuropathy, gender, age, and obesity; on soft surface, the length of sway was related to peripheral neuropathy, gender, and age, the influence of neuropathy was larger in males than in females, and closing the eyes increased further the difference between genders. The mean time to perform the "Up & Go" test was 11.6 ± 2.2 sec, with influence of peripheral neuropathy, gender, and age. In order to preserve the control of static upright posture during conditions with deficient sensory input, male patients with type 2 diabetes mellitus with no history of balance disorders may be more vulnerable than females, and obesity may decrease the static postural control in both males and females.

Postural Ataxia in Cerebellar Downbeat Nystagmus: Its Relation to Visual, Proprioceptive and Vestibular Signals and Cerebellar Atrophy.

PubMed

Helmchen, Christoph; Kirchhoff, Jan-Birger; Göttlich, Martin; Sprenger, Andreas

2017-01-01

The cerebellum integrates proprioceptive, vestibular and visual signals for postural control. Cerebellar patients with downbeat nystagmus (DBN) complain of unsteadiness of stance and gait as well as blurred vision and oscillopsia. The aim of this study was to elucidate the differential role of visual input, gaze eccentricity, vestibular and proprioceptive input on the postural stability in a large cohort of cerebellar patients with DBN, in comparison to healthy age-matched control subjects. Oculomotor (nystagmus, smooth pursuit eye movements) and postural (postural sway speed) parameters were recorded and related to each other and volumetric changes of the cerebellum (voxel-based morphometry, SPM). Twenty-seven patients showed larger postural instability in all experimental conditions. Postural sway increased with nystagmus in the eyes closed condition but not with the eyes open. Romberg's ratio remained stable and was not different from healthy controls. Postural sway did not change with gaze position or graviceptive input. It increased with attenuated proprioceptive input and on tandem stance in both groups but Romberg's ratio also did not differ. Cerebellar atrophy (vermal lobule VI, VIII) correlated with the severity of impaired smooth pursuit eye movements of DBN patients. Postural ataxia of cerebellar patients with DBN cannot be explained by impaired visual feedback. Despite oscillopsia visual feedback control on cerebellar postural control seems to be preserved as postural sway was strongest on visual deprivation. The increase in postural ataxia is neither related to modulations of single components characterizing nystagmus nor to deprivation of single sensory (visual, proprioceptive) inputs usually stabilizing stance. Re-weighting of multisensory signals and/or inappropriate cerebellar motor commands might account for this postural ataxia.

Postural Ataxia in Cerebellar Downbeat Nystagmus: Its Relation to Visual, Proprioceptive and Vestibular Signals and Cerebellar Atrophy

PubMed Central

Helmchen, Christoph; Kirchhoff, Jan-Birger; Göttlich, Martin; Sprenger, Andreas

2017-01-01

Background The cerebellum integrates proprioceptive, vestibular and visual signals for postural control. Cerebellar patients with downbeat nystagmus (DBN) complain of unsteadiness of stance and gait as well as blurred vision and oscillopsia. Objectives The aim of this study was to elucidate the differential role of visual input, gaze eccentricity, vestibular and proprioceptive input on the postural stability in a large cohort of cerebellar patients with DBN, in comparison to healthy age-matched control subjects. Methods Oculomotor (nystagmus, smooth pursuit eye movements) and postural (postural sway speed) parameters were recorded and related to each other and volumetric changes of the cerebellum (voxel-based morphometry, SPM). Results Twenty-seven patients showed larger postural instability in all experimental conditions. Postural sway increased with nystagmus in the eyes closed condition but not with the eyes open. Romberg’s ratio remained stable and was not different from healthy controls. Postural sway did not change with gaze position or graviceptive input. It increased with attenuated proprioceptive input and on tandem stance in both groups but Romberg’s ratio also did not differ. Cerebellar atrophy (vermal lobule VI, VIII) correlated with the severity of impaired smooth pursuit eye movements of DBN patients. Conclusions Postural ataxia of cerebellar patients with DBN cannot be explained by impaired visual feedback. Despite oscillopsia visual feedback control on cerebellar postural control seems to be preserved as postural sway was strongest on visual deprivation. The increase in postural ataxia is neither related to modulations of single components characterizing nystagmus nor to deprivation of single sensory (visual, proprioceptive) inputs usually stabilizing stance. Re-weighting of multisensory signals and/or inappropriate cerebellar motor commands might account for this postural ataxia. PMID:28056109

Spatial and temporal analysis of postural control in dyslexic children.

PubMed

Gouleme, Nathalie; Gerard, Christophe Loic; Bui-Quoc, Emmanuel; Bucci, Maria Pia

2015-07-01

The aim of this study is to examine postural control of dyslexic children using both spatial and temporal analysis. Thirty dyslexic (mean age 9.7±0.3years) and thirty non-dyslexic age-matched children participated in the study. Postural stability was evaluated using Multitest Equilibre from Framiral®. Posture was recorded in the following conditions: eyes open fixating a target (EO) and eyes closed (EC) on stable (-S-) and unstable (-U-) platforms. The findings of this study showed poor postural stability in dyslexic children with respect to the non-dyslexic children group, as demonstrated by both spatial and temporal analysis. In both groups of children postural control depends on the condition, and improves when the eyes are open on a stable platform. Dyslexic children have spectral power indices that are higher than in non-dyslexic children and they showed a shorter cancelling time. Poor postural control in dyslexic children could be due to a deficit in using sensory information most likely caused by impairment in cerebellar activity. The reliability of brain activation patterns, namely in using sensory input and cerebellar activity may explain the deficit in postural control in dyslexic children. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Back posture education in elementary schoolchildren: stability of two-year intervention effects.

PubMed

Geldhof, E; Cardon, G; De Bourdeaudhuij, I; De Clercq, D

2007-09-01

The study's first objective was to evaluate class teachers' efforts to promote good body mechanics after a structured back education program was finished and to evaluate whether their support during follow-up resulted in better intervention effects at 1-year follow-up. Secondary, the stability of intervention effects on children's back posture knowledge, fear-avoidance beliefs and back pain reports following a 2-school-year multi-factorial back education program was evaluated at 1-year follow-up. An additional focus was put on what young children learned about good body mechanics in the obligatory school curriculum compared to intensive back posture promotion. The quasi-experimental study included at baseline 398 elementary schoolchildren aged 8-11 years. The back education program consisted of 13 h back education and the stimulation of postural dynamism in the class through support and environmental changes lasting 2 school-years. Controls received the obligatory curriculum, not including back education. Evaluation consisted of a questionnaire, which was filled out by 121 intervention children and 124 controls at baseline, post-test and follow-up. Teachers were interviewed at the end of the follow-up school-year. Teachers continued with initiatives to increase postural dynamism in the class when they had been instructed about that matter. However, teachers' efforts to continue the promotion of good body mechanics showed no additional effect on children's knowledge. Improved back posture knowledge demonstrated stability at 1-year follow-up. Whereas the obligatory curriculum provided children with fundamental postural knowledge, the back posture program added important aspects. Fear-avoidance beliefs and self-reported pain were not increased at 1-year follow-up. The stable intervention effects point out that intensive implementation of a structured multifactorial back education program in the elementary school curriculum is effective.

Postural control and risk of falling in bipodalic and monopodalic stabilometric tests of healthy subjects before, after visuo-proprioceptive vestibulo-postural rehabilitation and at 3 months thereafter: role of the proprioceptive system.

PubMed

De Carli, P; Patrizi, M; Pepe, L; Cavaniglia, G; Riva, D; D'Ottavi, L R

2010-08-01

Nine healthy volunteers (6 males, 3 females), mean age 34.5 years (SD = 11.52), underwent a vestibulo-postural rehabilitation cycle with a visuo-proprioceptive-type stimulus. All subjects in the study group were evaluated by means of stabilometric bipodalic and monopodalic tests both before and immediately after treatment, and again 3 month thereafter. The Delos Postural Proprioceptive System®, DPPS (Delos, srl, Turin, Italy), was used in performing these stabilometric tests and in the rehabilitation exercises. The first aim of the study was to evaluate to what extent the functional level of the proprioceptive system was reliable, in healthy subjects, in the control of postural stability; the second was to demonstrate the possibility to increase this level by means of a novel visuo-proprioceptive feedback training; the last was to establish whether or not the increase achieved was permanent. The bipodalic test did not reveal any deficit in posture either before or after rehabilitation. The monopodalic test prior to treatment, with eyes closed, revealed, in 2/3 of the study group, evidence of the risk of falling, expressed as the precautional strategy (8.57 ± 6.18% SD). An increase in the proprioceptive activity, obtained in the subjects examined immediately after the visuo-proprioceptive vestibulo-postural rehabilitation, led, in the monopodalic test, with eyes closed, to a significant reduction in the risk of falling (with the precautional strategy equal to 1.09 ± 2.63% SD, p = 0.004). The monopodalic test, with eyes closed, 3 months after rehabilitation, demonstrated results not unlike those pre-treament with values, therefore, not more significant than those emerging from the pre-treatment test. Thus, from the above-mentioned data, it can be observed that, also in healthy subjects, there may be different levels of postural proprioceptive control related to a high risk of falling. These levels can be maintained constant for a certain period of time, until a significant reduction in the risk of falling is achieved, only if continuously stimulated by appropriate sensorial information.

Exercise countermeasures for bed-rest deconditioning

NASA Technical Reports Server (NTRS)

Greenleaf, John (Editor)

1993-01-01

The purpose for this 30-day bed rest study was to investigate the effects of short-term, high intensity isotonic and isokinetic exercise training on maintenance of working capacity (peak oxygen uptake), muscular strength and endurance, and on orthostatic tolerance, posture and gait. Other data were collected on muscle atrophy, bone mineralization and density, endocrine analyses concerning vasoactivity and fluid-electrolyte balance, muscle intermediary metabolism, and on performance and mood of the subjects. It was concluded that: The subjects maintained a relatively stable mood, high morale, and high esprit de corps throughout the study. Performance improved in nearly all tests in almost all the subjects. Isotonic training, as opposed to isokinetic exercise training, was associated more with decreasing levels of psychological tension, concentration, and motivation; and improvement in the quality of sleep. Working capacity (peak oxygen uptake) was maintained during bed rest with isotonic exercise training; it was not maintained with isokinetic or no exercise training. In general, there was no significant decrease in strength or endurance of arm or leg muscles during bed rest, in spite of some reduction in muscle size (atrophy) of some leg muscles. There was no effect of isotonic exercise training on orthostasis, since tilt-table tolerance was reduced similarly in all three groups following bed rest. Bed rest resulted in significant decreases of postural stability and self-selected step length, stride length, and walking velocity, which were not influenced by either exercise training regimen. Most pre-bed rest responses were restored by the fourth day of recovery.

Eye Movements Affect Postural Control in Young and Older Females

PubMed Central

Thomas, Neil M.; Bampouras, Theodoros M.; Donovan, Tim; Dewhurst, Susan

2016-01-01

Visual information is used for postural stabilization in humans. However, little is known about how eye movements prevalent in everyday life interact with the postural control system in older individuals. Therefore, the present study assessed the effects of stationary gaze fixations, smooth pursuits, and saccadic eye movements, with combinations of absent, fixed and oscillating large-field visual backgrounds to generate different forms of retinal flow, on postural control in healthy young and older females. Participants were presented with computer generated visual stimuli, whilst postural sway and gaze fixations were simultaneously assessed with a force platform and eye tracking equipment, respectively. The results showed that fixed backgrounds and stationary gaze fixations attenuated postural sway. In contrast, oscillating backgrounds and smooth pursuits increased postural sway. There were no differences regarding saccades. There were also no differences in postural sway or gaze errors between age groups in any visual condition. The stabilizing effect of the fixed visual stimuli show how retinal flow and extraocular factors guide postural adjustments. The destabilizing effect of oscillating visual backgrounds and smooth pursuits may be related to more challenging conditions for determining body shifts from retinal flow, and more complex extraocular signals, respectively. Because the older participants matched the young group's performance in all conditions, decreases of posture and gaze control during stance may not be a direct consequence of healthy aging. Further research examining extraocular and retinal mechanisms of balance control and the effects of eye movements, during locomotion, is needed to better inform fall prevention interventions. PMID:27695412

Eye Movements Affect Postural Control in Young and Older Females.

PubMed

Thomas, Neil M; Bampouras, Theodoros M; Donovan, Tim; Dewhurst, Susan

2016-01-01

Visual information is used for postural stabilization in humans. However, little is known about how eye movements prevalent in everyday life interact with the postural control system in older individuals. Therefore, the present study assessed the effects of stationary gaze fixations, smooth pursuits, and saccadic eye movements, with combinations of absent, fixed and oscillating large-field visual backgrounds to generate different forms of retinal flow, on postural control in healthy young and older females. Participants were presented with computer generated visual stimuli, whilst postural sway and gaze fixations were simultaneously assessed with a force platform and eye tracking equipment, respectively. The results showed that fixed backgrounds and stationary gaze fixations attenuated postural sway. In contrast, oscillating backgrounds and smooth pursuits increased postural sway. There were no differences regarding saccades. There were also no differences in postural sway or gaze errors between age groups in any visual condition. The stabilizing effect of the fixed visual stimuli show how retinal flow and extraocular factors guide postural adjustments. The destabilizing effect of oscillating visual backgrounds and smooth pursuits may be related to more challenging conditions for determining body shifts from retinal flow, and more complex extraocular signals, respectively. Because the older participants matched the young group's performance in all conditions, decreases of posture and gaze control during stance may not be a direct consequence of healthy aging. Further research examining extraocular and retinal mechanisms of balance control and the effects of eye movements, during locomotion, is needed to better inform fall prevention interventions.

Effects of ballates, step aerobics, and walking on balance in women aged 50-75 years.

PubMed

Clary, Sarah; Barnes, Cathleen; Bemben, Debra; Knehans, Allen; Bemben, Michael

2006-01-01

This study examined the effectiveness of Ballates training (strengthening of the central core musculature by the inception of balance techniques) compared to more traditional exercise programs, such as step aerobics and walking, on balance in women aged 50- 75 years. Participants were randomly assigned to one of three supervised training groups (1 hour/day, 3 days/week, 13 weeks), Ballates (n = 12), step aerobics (n = 17), or walking (n =15). Balance was measured by four different methods (modified Clinical Test for the Sensory Interaction on Balance - mCTSIB; Unilateral Stance with Eyes Open - US-EO or Eyes Closed - US-EC; Tandem Walk - TW; Step Quick Turn - SQT) using the NeuroCom Balance Master. A 2-way (Group and Trial) repeated measures ANOVA and post-hoc Bonferroni Pair-wise Comparisons were used to evaluate changes in the dependent variables used to describe stability and balance (sway velocity, turn sway, speed, and turn time). Measures of static postural stability and dynamic balance were similar for the three groups prior to training. Following the different exercise interventions, sway velocity on firm and foam surfaces (mCTSIB) with eyes closed (p < 0.05) increased for the Ballates group while the other two exercise groups either maintained or decreased their sway velocity following the training, therefore suggesting that these two groups either maintained or improved their balance. There were significant improvements in speed during the TW test (p < 0.01), and turn time (p < 0.01) and sway (p < 0.05) during the SQT test for each of the three groups. In general, all three training programs improved dynamic balance, however, step aerobics and walking programs resulted in be better improvements in postural stability or static balance when compared to the Ballates program. Key PointsExercise training can improve balanceNeed to consider both static and dynamic aspects of balance individuallyImproved balance can reduce the risk of fall.

Dynamic Postural-Stability Deficits After Cryotherapy to the Ankle Joint

PubMed Central

Fullam, Karl; Caulfield, Brian; Coughlan, Garrett F.; McGroarty, Mark; Delahunt, Eamonn

2015-01-01

Context  Decreased postural stability is a primary risk factor for lower limb musculoskeletal injuries. During athletic competitions, cryotherapy may be applied during short breaks in play or during half-time; however, its effects on postural stability remain unclear. Objective  To investigate the acute effects of a 15-minute ankle-joint cryotherapy application on dynamic postural stability. Design  Controlled laboratory study. Setting  University biomechanics laboratory. Patients or Other Participants  A total of 29 elite-level collegiate male field-sport athletes (age = 20.8 ± 1.12 years, height = 1.80 ± 0.06 m, mass = 81.89 ± 8.59 kg) participated. Intervention(s)  Participants were tested on the anterior (ANT), posterolateral (PL), and posteromedial (PM) reach directions of the Star Excursion Balance Test before and after a 15-minute ankle-joint cryotherapy application. Main Outcome Measure(s)  Normalized reach distances; sagittal-plane kinematics of the hip, knee, and ankle joints; and associated mean velocity of the center-of-pressure path during performance of the ANT, PL, and PM reach directions of the Star Excursion Balance Test. Results  We observed a decrease in reach-distance scores for the ANT, PL, and PM reach directions from precryotherapy to postcryotherapy (P < .05). No differences were observed in hip-, knee-, or ankle-joint sagittal-plane kinematics (P > .05). We noted a decrease in mean velocity of the center-of-pressure path from precryotherapy to postcryotherapy (P < .05) in all reach directions. Conclusions  Dynamic postural stability was adversely affected immediately after cryotherapy to the ankle joint. PMID:26285088

Smooth-pursuit eye movements without head movement disrupt the static body balance.

PubMed

Kim, Sang-Yeob; Moon, Byeong-Yeon; Cho, Hyun Gug

2016-04-01

[Purpose] To investigate the changes of body balance in static posture in smooth-pursuit eye movements (SPEMs) without head movement. [Subjects and Methods] Forty subjects (24 males, 16 females) aged 23.24 ± 2.58 years participated. SPEMs were activated in three directions (horizontal, vertical, and diagonal movements); the target speed was set at three conditions (10°/s, 20°/s, and 30°/s); and the binocular visual field was limited to 50°. To compare the body balance changes, the general stability (ST) and the fall risk index (FI) were measured with TETRAX. The subjects wore a head-neck collar and stood on a balance plate for 32 s during each measurement in three directions. SPEMs were induced to each subject with nine target speeds and directions. All measured values were compared with those in stationary fixation. [Results] The ST and FI increased significantly in all SPEMs directions, with an increased target speed than that in stationary fixation. In the same condition of the target speed, the FI had the highest value relative to diagonal SPEMs. [Conclusion] SPEMs without head movement disrupt the stability of body balance in a static posture, and diagonal SPEMs may have a more negative effect in maintaining body balance than horizontal or vertical SPEMs.

Effects of Inspired CO2 and Breathing Resistance on Neurocognitive and Postural Stability in U.S. Navy Divers

DTIC Science & Technology

2015-08-01

Wii Balance Board . Amplitude and sample entropy...of the subtests. Balance testing Alterations in postural stability (i.e., balance ) were assessed using a Nintendo Wii Balance Board (Nintendo...29. P. Scaglioni-Solano, L. F. Aragón-Vargas, "Validity and Reliability of the Nintendo Wii Balance Board to Assess Standing Balance and

Vibration-enhanced posture stabilization achieved by tactile supplementation: may blind individuals get extra benefits?

PubMed

Magalhães, Fernando Henrique; Kohn, André Fabio

2011-08-01

Diminished balance ability poses a serious health risk due to the increased likelihood of falling, and impaired postural stability is significantly associated with blindness and poor vision. Noise stimulation (by improving the detection of sub-threshold somatosensory information) and tactile supplementation (i.e., additional haptic information provided by an external contact surface) have been shown to improve the performance of the postural control system. Moreover, vibratory noise added to the source of tactile supplementation (e.g., applied to a surface that the fingertip touches) has been shown to enhance balance stability more effectively than tactile supplementation alone. In view of the above findings, in addition to the well established consensus that blind subjects show superior abilities in the use of tactile information, we hypothesized that blind subjects may take extra benefits from the vibratory noise added to the tactile supplementation and hence show greater improvements in postural stability than those observed for sighted subjects. If confirmed, this hypothesis may lay the foundation for the development of noise-based assistive devices (e.g., canes, walking sticks) for improving somatosensation and hence prevent falls in blind individuals. Copyright © 2011 Elsevier Ltd. All rights reserved.

Reconstructed phase spaces of intrinsic mode functions. Application to postural stability analysis.

PubMed

Snoussi, Hichem; Amoud, Hassan; Doussot, Michel; Hewson, David; Duchêne, Jacques

2006-01-01

In this contribution, we propose an efficient nonlinear analysis method characterizing postural steadiness. The analyzed signal is the displacement of the centre of pressure (COP) collected from a force plate used for measuring postural sway. The proposed method consists of analyzing the nonlinear dynamics of the intrinsic mode functions (IMF) of the COP signal. The nonlinear properties are assessed through the reconstructed phase spaces of the different IMFs. This study shows some specific geometries of the attractors of some intrinsic modes. Moreover, the volume spanned by the geometric attractors in the reconstructed phase space represents an efficient indicator of the postural stability of the subject. Experiments results corroborate the effectiveness of the method to blindly discriminate young subjects, elderly subjects and subjects presenting a risk of falling.

Individual differences in the ability to identify, select and use appropriate frames of reference for perceptuo-motor control.

PubMed

Isableu, B; Ohlmann, T; Cremieux, J; Vuillerme, N; Amblard, B; Gresty, M A

2010-09-01

The causes of the interindividual differences (IDs) in how we perceive and control spatial orientation are poorly understood. Here, we propose that IDs partly reflect preferred modes of spatial referencing and that these preferences or "styles" are maintained from the level of spatial perception to that of motor control. Two groups of experimental subjects, one with high visual field dependency (FD) and one with marked visual field independency (FI) were identified by the Rod and Frame Test, which identifies relative dependency on a visual frame of reference (VFoR). FD and FI subjects were tasked with standing still in conditions of increasing postural difficulty while visual cues of self-orientation (a visual frame tilted in roll) and self-motion (in stroboscopic illumination) were varied and in darkness to assess visual dependency. Postural stability, overall body orientation and modes of segmental stabilization relative to either external (space) or egocentric (adjacent segments) frames of reference in the roll plane were analysed. We hypothesized that a moderate challenge to balance should enhance subjects' reliance on VFoR, particularly in FD subjects, whereas a substantial challenge should constrain subjects to use a somatic-vestibular based FoR to prevent falling in which case IDs would vanish. The results showed that with increasing difficulty, FD subjects became more unstable and more disoriented shown by larger effects of the tilted visual frame on posture. Furthermore, their preference to coalign body/VFoR coordinate systems lead to greater fixation of the head-trunk articulation and stabilization of the hip in space, whereas the head and trunk remained more stabilized in space with the hip fixed on the leg in FI subjects. These results show that FD subjects have difficulties at identifying and/or adopting a more appropriate FoR based on proprioceptive and vestibular cues to regulate the coalignment of posturo/exocentric FoRs. The FI subjects' resistance in the face of altered VFoR and balance challenge resides in their greater ability to coordinate movement by coaligning body axes with more appropriate FoRs (provided by proprioceptive and vestibular co-variance). Copyright (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Components of Standing Postural Control Evaluated in Pediatric Balance Measures: A Scoping Review.

PubMed

Sibley, Kathryn M; Beauchamp, Marla K; Van Ooteghem, Karen; Paterson, Marie; Wittmeier, Kristy D

2017-10-01

To identify measures of standing balance validated in pediatric populations, and to determine the components of postural control captured in each tool. Electronic searches of MEDLINE, Embase, and CINAHL databases using key word combinations of postural balance/equilibrium, psychometrics/reproducibility of results/predictive value of tests, and child/pediatrics; gray literature; and hand searches. Inclusion criteria were measures with a stated objective to assess balance, with pediatric (≤18y) populations, with at least 1 psychometric evaluation, with at least 1 standing task, with a standardized protocol and evaluation criteria, and published in English. Two reviewers independently identified studies for inclusion. There were 21 measures included. Two reviewers extracted descriptive characteristics, and 2 investigators independently coded components of balance in each measure using a systems perspective for postural control, an established framework for balance in pediatric populations. Components of balance evaluated in measures were underlying motor systems (100% of measures), anticipatory postural control (72%), static stability (62%), sensory integration (52%), dynamic stability (48%), functional stability limits (24%), cognitive influences (24%), verticality (9%), and reactive postural control (0%). Assessing children's balance with valid and comprehensive measures is important for ensuring development of safe mobility and independence with functional tasks. Balance measures validated in pediatric populations to date do not comprehensively assess standing postural control and omit some key components for safe mobility and independence. Existing balance measures, that have been validated in adult populations and address some of the existing gaps in pediatric measures, warrant consideration for validation in children. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Postural stability and quality of life after guided and self-training among older adults residing in an institutional setting

PubMed Central

Tuunainen, Eeva; Rasku, Jyrki; Jäntti, Pirkko; Moisio-Vilenius, Päivi; Mäkinen, Erja; Toppila, Esko; Pyykkö, Ilmari

2013-01-01

Purpose To evaluate whether rehabilitation of muscle force or balance improves postural stability and quality of life (QoL), and whether self-administered training is comparable with guided training among older adults residing in an institutional setting. Patients and methods A randomized, prospective intervention study was undertaken among 55 elderly patients. Three intervention groups were evaluated: a muscle force training group; a balance and muscle force training group; and a self-administered training group. Each group underwent 1-hour-long training sessions, twice a week, for 3 months. Postural stability was measured at onset, after 3 months, and after 6 months. Time-domain-dependent body sway variables were calculated. The fall rate was evaluated for 3 years. General health related quality of life (HRQoL) was measured with a 15D instrument. Postural stability was used as a primary outcome, with QoL and falls used as secondary outcomes. Results Muscle force trainees were able to undertake training, progressing towards more strenuous exercises. In posturography, the number of spiky oscillations was reduced after training, and stationary fields of torque moments of the ankle increased, providing better postural stability in all groups; in particular, the zero crossing rate of weight signal and the number of low variability episodes in the stabilogram were improved after training. While no difference was found between different training groups in posturography outcomes, a reduction of fall rate was significant in only the guided training groups. A significant part of the variability of the QoL could be explained by the posturography outcome (46%). However, the outcome of training was associated with a reduced QoL. Conclusion Even moderate or severely demented residents could do exercises in five-person groups under the supervision of a physiotherapist. An improvement in postural stability was observed in all training groups, indicating that even self-administered training could be beneficial. Posturography outcome indicated that training alters the postural strategy by reducing the oscillatory fluctuations of body sway signal. However, only guided training tended to reduce falls. Short training intervention programs may decrease QoL by changing the elderly’s daily routine and making it more active and exhausting. PMID:24072969

Anatomy and histochemistry of spread-wing posture in birds. 3. Immunohistochemistry of flight muscles and the "shoulder lock" in albatrosses.

PubMed

Meyers, Ron A; Stakebake, Eric F

2005-01-01

As a postural behavior, gliding and soaring flight in birds requires less energy than flapping flight. Slow tonic and slow twitch muscle fibers are specialized for sustained contraction with high fatigue resistance and are typically found in muscles associated with posture. Albatrosses are the elite of avian gliders; as such, we wanted to learn how their musculoskeletal system enables them to maintain spread-wing posture for prolonged gliding bouts. We used dissection and immunohistochemistry to evaluate muscle function for gliding flight in Laysan and Black-footed albatrosses. Albatrosses possess a locking mechanism at the shoulder composed of a tendinous sheet that extends from origin to insertion throughout the length of the deep layer of the pectoralis muscle. This fascial "strut" passively maintains horizontal wing orientation during gliding and soaring flight. A number of muscles, which likely facilitate gliding posture, are composed exclusively of slow fibers. These include Mm. coracobrachialis cranialis, extensor metacarpi radialis dorsalis, and deep pectoralis. In addition, a number of other muscles, including triceps scapularis, triceps humeralis, supracoracoideus, and extensor metacarpi radialis ventralis, were found to have populations of slow fibers. We believe that this extensive suite of uniformly slow muscles is associated with sustained gliding and is unique to birds that glide and soar for extended periods. These findings suggest that albatrosses utilize a combination of slow muscle fibers and a rigid limiting tendon for maintaining a prolonged, gliding posture.

PREHAB vs. REHAB - presurgical treatment in vestibular schwannoma surgery enhances recovery of postural control better than postoperative rehabilitation: Retrospective case series.

PubMed

Tjernström, Fredrik; Fransson, Per-Anders; Kahlon, Babar; Karlberg, Mikael; Lindberg, Sven; Siesjö, Peter; Magnusson, Måns

2018-01-01

To evaluate post-surgical postural stability when treating patients with remaining vestibular function with intratympanic gentamicin (PREHAB) prior to schwannoma surgery. 44 consecutive patients with some form remaining vestibular function scheduled for vestibular schwannoma surgery. 20 were medically deafferented with intratympanic gentamicin before surgery and 24 were not. Both groups were of the same age, had the same tumor size, same type of surgery, and same perioperative sensory rehabilitation (training exercises), and no surgical complications. Postural stability measured as energy expenditure while standing on a force platform during vibratory stimulation of the calf muscles, performed prior to surgery (or gentamicin treatment) and 6 months after surgery. Patients pretreated with gentamicin had significantly better postural stability at the time for follow-up (p < 0.05) and displayed a better adaptive capacity when faced with a postural challenge (p < 0.01). They were also able to use vision more efficiently to control their stability (p < 0.05). By separating the sensory loss (through intratympanic gentamicin, that ablates the remaining vestibular function) from the intracranial surgical trauma, the postural control system benefited from a better short-term (adaptation) and long-term (habituation) recovery, when experiencing a postural challenge or resolving a sensory conflict. The benefits could be attributed to; active and continuous motor learning as the vestibular function slowly attenuates; no concomitant central nervous dysfunction due to effects from neurosurgery, thus allowing time for a separate unimpeded recovery process with more limited challenges and objectives; and the initiation and certain progression of sensory reweighting processes allowed prior to surgery. In contrast, worse compensation could be due to; immobilization from nausea after surgery, harmful amount of stress and cognitive dysfunction from the combination of surgical and sensory trauma and an abrupt vestibular deafferentation and its consequences on sensory reweighting.

Revisiting the body-schema concept in the context of whole-body postural-focal dynamics.

PubMed

Morasso, Pietro; Casadio, Maura; Mohan, Vishwanathan; Rea, Francesco; Zenzeri, Jacopo

2015-01-01

The body-schema concept is revisited in the context of embodied cognition, further developing the theory formulated by Marc Jeannerod that the motor system is part of a simulation network related to action, whose function is not only to shape the motor system for preparing an action (either overt or covert) but also to provide the self with information on the feasibility and the meaning of potential actions. The proposed computational formulation is based on a dynamical system approach, which is linked to an extension of the equilibrium-point hypothesis, called Passive Motor Paradigm: this dynamical system generates goal-oriented, spatio-temporal, sensorimotor patterns, integrating a direct and inverse internal model in a multi-referential framework. The purpose of such computational model is to operate at the same time as a general synergy formation machinery for planning whole-body actions in humanoid robots and/or for predicting coordinated sensory-motor patterns in human movements. In order to illustrate the computational approach, the integration of simultaneous, even partially conflicting tasks will be analyzed in some detail with regard to postural-focal dynamics, which can be defined as the fusion of a focal task, namely reaching a target with the whole-body, and a postural task, namely maintaining overall stability.

Revisiting the Body-Schema Concept in the Context of Whole-Body Postural-Focal Dynamics

PubMed Central

Morasso, Pietro; Casadio, Maura; Mohan, Vishwanathan; Rea, Francesco; Zenzeri, Jacopo

2015-01-01

The body-schema concept is revisited in the context of embodied cognition, further developing the theory formulated by Marc Jeannerod that the motor system is part of a simulation network related to action, whose function is not only to shape the motor system for preparing an action (either overt or covert) but also to provide the self with information on the feasibility and the meaning of potential actions. The proposed computational formulation is based on a dynamical system approach, which is linked to an extension of the equilibrium-point hypothesis, called Passive Motor Paradigm: this dynamical system generates goal-oriented, spatio-temporal, sensorimotor patterns, integrating a direct and inverse internal model in a multi-referential framework. The purpose of such computational model is to operate at the same time as a general synergy formation machinery for planning whole-body actions in humanoid robots and/or for predicting coordinated sensory–motor patterns in human movements. In order to illustrate the computational approach, the integration of simultaneous, even partially conflicting tasks will be analyzed in some detail with regard to postural-focal dynamics, which can be defined as the fusion of a focal task, namely reaching a target with the whole-body, and a postural task, namely maintaining overall stability. PMID:25741274

From an urologist view: are we safe with endoscopic surgery? Overview of ergonomic problems encountered by the urologist during video endoscopic surgery.

PubMed

Sataa, Sallami; Benzarti, Aida; Ben Jemaa, Abdelmajid

2012-12-01

The importance of minimally invasive surgery in urology has constantly increased in the last 20 years. Endoscopic resection of prostate and bladder tumors is actually a gold standard with many advantages for patients. To analyze the problems related to the ergonomic conditions faced by urologist during video endoscopic surgery by review of the recent literature. All evidence-based experimental ergonomic studies conducted in the fields of urology endoscopic surgery and applied ergonomics for other professions working with a display were identified by PubMed searches. Data from ergonomic studies were evaluated in terms of efficiency as well as comfort and safety aspects. Constraint postures for urologists are described and ergonomic requirements for optimal positions are discussed. The ergonomics of urological endoscopic surgery place urologists at risk for potential injury. The amount of neck flexion or extension, the amount of shoulder girdle adduction or abduction used, and stability of the upper extremities during surgery; which are maintained in a prolonged static posture; are the main risk factors. All these constraints may lead to muscle and joint fatigue, pain, and eventual musculoskeletal injury. Moreover, these issues may impact surgical accuracy. Urologist posture, operating period, training are important ergonomic factor during video surgery to prevent musculoskeletal disorders.

Comparative study of computerized dynamic posturography and the SwayStar system in healthy subjects.

PubMed

Faraldo-García, Ana; Santos-Pérez, Sofía; Crujeiras, Rosa; Labella-Caballero, Torcuato; Soto-Varela, Andrés

2012-03-01

For healthy subjects, posturography and SwayStar™ results are basically comparable, when they are obtained under the same sensory stimulation conditions. However, the management of the information and the mathematical analyses in the two systems are not comparable. Postural control represents man's ability to maintain the center of pressures inside the limits of stability. Posturography is a set of techniques that objectively studies and quantifies the postural control. The present study analyzed the different parameters of the dynamic computerized posturography and SwayStar systems related to balance, to determine whether the results of the two systems in the same healthy subject are equivalent. Seventy healthy individuals, with a mean age of 44.9 years, were homogeneously divided into seven age groups. Postural studies with a Neurocom(®) Smart Balance Master posturography platform (sensorial organization test), with the SwayStar(®) system (14 tests), and another sensorial organization test were recorded simultaneously with the two posturographs. The Pearson correlation test was used for the statistical study (p < 0.05). Comparison of the independent records showed correlation only in the Romberg position with eyes closed on a normal surface and in the Romberg position with open eyes on moving/foam surface. We found correlation for all conditions when simultaneously recorded.

Stability Design and Response to Waves by Batoids.

PubMed

Fish, Frank E; Hoffman, Jessica L

2015-10-01

Unsteady flows in the marine environment can affect the stability and locomotor costs of animals. For fish swimming at shallow depths, waves represent a form of unsteady flow. Waves consist of cyclic oscillations, during which the water moves in circular or elliptical orbits. Large gravity waves have the potential to displace fish both cyclically and in the direction of wave celerity for animals floating in the water column or holding station on the bottom. Displacement of a fish can exceed its stability control capability when the size of the wave orbit is equivalent to the size of the fish. Previous research into compensatory behaviors of fishes to waves has focused on pelagic osteichthyan fishes with laterally compressed bodies. However, dorsoventrally compressed batoid rays must also contend with waves. Examination of rays subjected to waves showed differing strategies for stability between pelagic and demersal species. Pelagic cownose rays (Rhinoptera bonasus) would glide through or be transported by waves, maintaining a positive dihedral of the wing-like pectoral fins. Demersal Atlantic stingrays (Dasyatis sabina) and freshwater rays (Potamotrygon motoro) maintained contact with the bottom and performed compensatory fin motions and body postures. The ability to limit displacement due to wave action by the demersal rays was also a function of the bottom texture. The ability of rays to maintain stability due to wave action suggests mechanisms to compensate for the velocity flux of the water impinging on the large projected area of the enlarged pectoral fins of rays. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

An analysis of the activity and muscle fatigue of the muscles around the neck under the three most frequent postures while using a smartphone

PubMed Central

Choi, Jung-Hyun; Jung, Min-Ho; Yoo, Kyung-Tae

2016-01-01

[Purpose] The purpose of this study was to identify changes in the activity and fatigue of the splenius capitis and upper trapezius muscles, which are agonists to the muscles supporting the head, under the three postures most frequently adopted while using a smartphone. [Subjects and Methods] The subjects were 15 college students in their 20s. They formed a single group and had to adopt three different postures (maximum bending, middle bending, and neutral). While the 15 subjects maintained the postures, muscle activity and fatigue were measured using surface electromyography. [Results] Comparison of the muscle fatigue caused by each posture showed statistically significant differences for the right splenius capitis, left splenius capitis, and left upper trapezius muscles. In addition, maintaining the maximum bending posture while using a smartphone resulted in higher levels of fatigue in the right splenius capitis, left splenius capitis, and left upper trapezius muscles compared with those for the middle bending posture. [Conclusion] Therefore, this study suggests that individuals should bend their neck slightly when using a smartphone, rather than bending it too much, or keep their neck straight to reduce fatigue of the cervical erector muscles. PMID:27313393

Effect of Seat Surface Inclination on Postural Stability and forward Reaching Efficiency in Children with Spastic Cerebral Palsy

ERIC Educational Resources Information Center

Cherng, Rong-Ju; Lin, Hui-Chen; Ju, Yun-Huei; Ho, Chin-Shan

2009-01-01

The purpose of this study was to examine the effect of seat surface inclination on postural stability and forward reaching efficiency in 10 children with spastic cerebral palsy (CP) and 16 typically developing (TD) children. The children performed a static sitting and a forward reaching task while sitting on a height- and inclination-adjustable…

Impaired limb reaction to displacement of center of gravity in rats with unilateral striatal ischemic injury.

PubMed

Nobile, Cameron W; Palmateer, Julie M; Kane, Jackie; Hurn, Patricia D; Schallert, Timothy; Adkins, DeAnna L

2014-10-01

Clinical stroke often results in impaired balance and increased vulnerability to severe injuries due to falling. To evaluate potential preclinical treatments that might target these deficits, it will be important to include tests capable of assessing these impairments chronically in animal models. Previously, we developed a postural instability test (PIT) that revealed chronic, unilateral impairments in postural stability in rat models of hemi-Parkinson's disease (PD) and of unilateral cervical spinal cord injury. Here, we investigated whether this test was also capable of revealing long-term stroke-induced impairments in postural support in rats. Additionally, we examined the ability of more common tests of sensorimotor function to detect chronic impairments. We found that the PIT detected chronic deficits in postural stability/balance enduring for up to 6 weeks post-stroke, outlasting impairments detected in other tests of forelimb sensorimotor function, including asymmetries in upright postural support (cylinder test) and vibrissae-evoked forelimb placing.

PubMed Central

CARLI, P.; PATRIZI, M.; PEPE, L.; CAVANIGLIA, G.; RIVA, D.; D’OTTAVI, L.R.

2010-01-01

SUMMARY Nine healthy volunteers (6 males, 3 females), mean age 34.5 years (SD = 11.52), underwent a vestibulo-postural rehabilitation cycle with a visuo-proprioceptive-type stimulus. All subjects in the study group were evaluated by means of stabilometric bipodalic and monopodalic tests both before and immediately after treatment, and again 3 month thereafter. The Delos Postural Proprioceptive System®, DPPS (Delos, srl, Turin, Italy), was used in performing these stabilometric tests and in the rehabilitation exercises. The first aim of the study was to evaluate to what extent the functional level of the proprioceptive system was reliable, in healthy subjects, in the control of postural stability; the second was to demonstrate the possibility to increase this level by means of a novel visuo-proprioceptive feedback training; the last was to establish whether or not the increase achieved was permanent. The bipodalic test did not reveal any deficit in posture either before or after rehabilitation. The monopodalic test prior to treatment, with eyes closed, revealed, in 2/3 of the study group, evidence of the risk of falling, expressed as the precautional strategy (8.57 ± 6.18% SD). An increase in the proprioceptive activity, obtained in the subjects examined immediately after the visuo-proprioceptive vestibulo-postural rehabilitation, led, in the monopodalic test, with eyes closed, to a significant reduction in the risk of falling (with the precautional strategy equal to 1.09 ± 2.63% SD, p = 0.004). The monopodalic test, with eyes closed, 3 months after rehabilitation, demonstrated results not unlike those pre-treament with values, therefore, not more significant than those emerging from the pre-treatment test. Thus, from the above-mentioned data, it can be observed that, also in healthy subjects, there may be different levels of postural proprioceptive control related to a high risk of falling. These levels can be maintained constant for a certain period of time, until a significant reduction in the risk of falling is achieved, only if continuously stimulated by appropriate sensorial information. PMID:21253283

Postural Hypo-Reactivity in Autism Is Contingent on Development and Visual Environment: A Fully Immersive Virtual Reality Study

ERIC Educational Resources Information Center

Greffou, Selma; Bertone, Armando; Hahler, Eva-Maria; Hanssens, Jean-Marie; Mottron, Laurent; Faubert, Jocelyn

2012-01-01

Although atypical motor behaviors have been associated with autism, investigations regarding their possible origins are scarce. This study assessed the visual and vestibular components involved in atypical postural reactivity in autism. Postural reactivity and stability were measured for younger (12-15 years) and older (16-33 years) autistic…

Effects of Dyslexia on Postural Control in Adults

ERIC Educational Resources Information Center

Patel, M.; Magnusson, M.; Lush, D.; Gomez, S.; Fransson, P. A.

2010-01-01

Dyslexia has been shown to affect postural control. The aim of the present study was to investigate the difference in postural stability measured as torque variance in an adult dyslexic group (n=14, determined using the Adult Dyslexia Checklist (ADCL) and nonsense word repetition test) and an adult non-dyslexic group (n=39) on a firm surface and…

Regularity of center-of-pressure trajectories depends on the amount of attention invested in postural control

PubMed Central

Donker, Stella F.; Roerdink, Melvyn; Greven, An J.

2007-01-01

The influence of attention on the dynamical structure of postural sway was examined in 30 healthy young adults by manipulating the focus of attention. In line with the proposed direct relation between the amount of attention invested in postural control and regularity of center-of-pressure (COP) time series, we hypothesized that: (1) increasing cognitive involvement in postural control (i.e., creating an internal focus by increasing task difficulty through visual deprivation) increases COP regularity, and (2) withdrawing attention from postural control (i.e., creating an external focus by performing a cognitive dual task) decreases COP regularity. We quantified COP dynamics in terms of sample entropy (regularity), standard deviation (variability), sway-path length of the normalized posturogram (curviness), largest Lyapunov exponent (local stability), correlation dimension (dimensionality) and scaling exponent (scaling behavior). Consistent with hypothesis 1, standing with eyes closed significantly increased COP regularity. Furthermore, variability increased and local stability decreased, implying ineffective postural control. Conversely, and in line with hypothesis 2, performing a cognitive dual task while standing with eyes closed led to greater irregularity and smaller variability, suggesting an increase in the “efficiency, or “automaticity” of postural control”. In conclusion, these findings not only indicate that regularity of COP trajectories is positively related to the amount of attention invested in postural control, but also substantiate that in certain situations an increased internal focus may in fact be detrimental to postural control. PMID:17401553

Postural Analysis in Time and Frequency Domains in Patients with Ehlers-Danlos Syndrome

ERIC Educational Resources Information Center

Galli, Manuela; Rigoldi, Chiara; Celletti, Claudia; Mainardi, Luca; Tenore, Nunzio; Albertini, Giorgio; Camerota, Filippo

2011-01-01

The goal of this work is to analyze postural control in Ehlers-Danlos syndrome (EDS) participants in time and frequency domain. This study considered a pathological group composed by 22 EDS participants performing a postural test consisting in maintaining standing position over a force platform for 30 s in two conditions: open eyes (OE) and closed…

Impairments of postural stability, core endurance, fall index and functional mobility skills in patients with patello femoral pain syndrome.

PubMed

Yilmaz Yelvar, Gul Deniz; Çirak, Yasemin; Dalkilinç, Murat; Demir, Yasemin Parlak; Baltaci, Gul; Kömürcü, Mahmut; Yelvar, Gul Deniz Yilmaz

2016-06-30

Postural control allows performance of daily and sports activities. The previous studies show that postural sway inceases in orthopaedic injuries such as osteoarthritis and total knee arthroplasty. To compare postural sway, risk of falling and function between individuals with and without patellofemoral pain syndrome (PFS). This study included 22 subjects with patellofemoral pain syndrome, age-matched pain-free 22 females serving as a control group. Visual anolog scale and Kujala were used to evaluate the pain. Posturographic assesment was performed by Tetrax posturographic device. Biering Modified Sorenson test for extensor endurance and sit-up test for flexor endurance were used for the evaluation of trunk endurance. Timed get-up and go test was used for lower extremity function. The Student's t Test was used to compare variables between the groups. The Pearson correlation coefficients were calculated to examine correlation between the quantitative variables. Postural sway included eyes open without pillow, eyes open on pillow, eyes closed on pillow, risk of falling, function and postural stabilization included flexor endurance, extansor endurance are impared in patient with patellofemoral pain syndrome when compare to controls. In subjects with PFPS increased postural sway significantly associated with body mass index (r= 0.52), pain duration (r= 0.43), postural control (extansor endurance) (r= -0.50) and risk of falling (r= 0.62) on pillow with open eyes. In addition we found function significantly related with postural control (extansor endurance and flexor endurance) (r= -0.59 and r= -0.59) and risk of falling (r= 0.77)CONCLUSIONS: Decreased neuromuscular control of the trunk core and increased postural sway and falling risk were found in patients with PFPS. Patients may be evaluated for deficits in postural control and falling risk before treatment.

Velocity dependence of vestibular information for postural control on tilting surfaces

PubMed Central

Kluzik, JoAnn; Hlavacka, Frantisek

2016-01-01

Vestibular information is known to be important for postural stability on tilting surfaces, but the relative importance of vestibular information across a wide range of surface tilt velocities is less clear. We compared how tilt velocity influences postural orientation and stability in nine subjects with bilateral vestibular loss and nine age-matched, control subjects. Subjects stood on a force platform that tilted 6 deg, toes-up at eight velocities (0.25 to 32 deg/s), with and without vision. Results showed that visual information effectively compensated for lack of vestibular information at all tilt velocities. However, with eyes closed, subjects with vestibular loss were most unstable within a critical tilt velocity range of 2 to 8 deg/s. Subjects with vestibular deficiency lost their balance in more than 90% of trials during the 4 deg/s condition, but never fell during slower tilts (0.25–1 deg/s) and fell only very rarely during faster tilts (16–32 deg/s). At the critical velocity range in which falls occurred, the body center of mass stayed aligned with respect to the surface, onset of ankle dorsiflexion was delayed, and there was delayed or absent gastrocnemius inhibition, suggesting that subjects were attempting to actively align their upper bodies with respect to the moving surface instead of to gravity. Vestibular information may be critical for stability at velocities of 2 to 8 deg/s because postural sway above 2 deg/s may be too fast to elicit stabilizing responses through the graviceptive somatosensory system, and postural sway below 8 deg/s may be too slow for somatosensory-triggered responses or passive stabilization from trunk inertia. PMID:27486101

Effect of midsole thickness of dance shoes on dynamic postural stability.

PubMed

Wyon, Matthew A; Cloak, Ross; Lucas, Josephine; Clarke, Frances

2013-12-01

Landing from jumps is one of the main causes of injury within dance. A number of studies have reported a negative effect of shoe midsole thickness on lower limb kinematics during running due to the reduction in afferent sensory outputs from the foot's epithelium. The purpose of this study was to examine the influence of varying midsole thicknesses in dance shoes on dynamic postural stability during a single-leg landing. Twenty-eight female undergraduate dance participants volunteered for the study. They carried out three trials under four conditions: barefoot and in ballet flats (2 mm midsole thickness), jazz shoes (7 mm), and dance sneakers (30 mm). The task consisted of a single-leg forward jump over a hurdle at 50% of their maximal vertical jump height, landing on a force platform, and balancing for 3 seconds. The stability indices for vertical stability (VSI), anterior-posterior stability (APSI), medial-lateral stability (MLSI), and dynamic postural stability (DPSI) were calculated using Wikstrom's revised method. Significant differences were reported between the midsole thicknesses for both DPSI and VSI (p<0.01). No statistical differences were noted for the indices SPSI or MLSI. The present data agree with the running studies in that increased midsole thickness has a negative influence on landing stability.

Vestibular ablation and a semicircular canal prosthesis affect postural stability during head turns

PubMed Central

Thompson, Lara A.; Haburcakova, Csilla; Lewis, Richard F.

2016-01-01

In our study, we examined postural stability during head turns for two rhesus monkeys: one, single animal study contrasted normal and mild bilateral vestibular ablation and a second animal study contrasted severe bilateral vestibular ablation with and without prosthetic stimulation. The monkeys freely stood, unrestrained on a balance platform and made voluntary head turns between visual targets. To quantify each animals’ posture, motions of the head and trunk, as well as torque about the body’s center-of-mass, were measured. In the mildly ablated animal, we observed less foretrunk sway in comparison to the normal state. When the canal prosthesis provided electric stimulation to the severely ablated animal, it showed a decrease in trunk sway during head turns. Because the rhesus monkey with severe bilateral vestibular loss exhibited a decrease in trunk sway when receiving vestibular prosthetic stimulation, we propose that the prosthetic electrical stimulation partially restored head velocity information. Our results provide an indication that a semicircular canal prosthesis may be an effective way to improve postural stability in patients with severe peripheral vestibular dysfunction. PMID:27405997

Space flight and neurovestibular adaptation

NASA Technical Reports Server (NTRS)

Reschke, M. F.; Bloomberg, J. J.; Harm, D. L.; Paloski, W. H.

1994-01-01

Space flight represents a form of sensory stimulus rearrangement requiring modification of established terrestrial response patterns through central reinterpretation. Evidence of sensory reinterpretation is manifested as postflight modifications of eye/head coordination, locomotor patterns, postural control strategies, and illusory perceptions of self or surround motion in conjunction with head movements. Under normal preflight conditions, the head is stabilized during locomotion, but immediately postflight reduced head stability, coupled with inappropriate eye/head coordination, results in modifications of gait. Postflight postural control exhibits increased dependence on vision which compensates for inappropriate interpretation of otolith and proprioceptive inputs. Eye movements compensatory for perceived self motion, rather than actual head movements have been observed postflight. Overall, the in-flight adaptive modification of head stabilization strategies, changes in head/eye coordination, illusionary motion, and postural control are maladaptive for a return to the terrestrial environment.

Motion sickness elicited by passive rotation in squirrel monkeys

NASA Technical Reports Server (NTRS)

Daunton, Nancy G.; Fox, Robert A.

1991-01-01

Current theory and recent evidence suggest that motion sickness occurs under conditions of sensory input in which the normal motor programs for producing eye, head, and body movements are not functionally effective, i.e. under conditions in which there are difficulties in maintaining posture and controlling eye movements. Conditions involving conflicting or inconsistent visual-vestibular (VV) stimulation should thus result in greater sickness rates since the existing motor programs do not produce effective control of eye-head-body movements under such conditions. It is felt that the relationship of postural control to motion sickness is an important one and one often overlooked. The results are reported which showed that when postural requirements were minimized by fully restraining squirrel monkeys during hypogravity parabolic flight, no animals became motion sick, but over 80 percent of the same 11 animals became sick if they were unrestrained and maintained control of their posture.

Active ocular vergence improves postural control in elderly as close viewing distance with or without a single cognitive task.

PubMed

Matheron, Eric; Yang, Qing; Delpit-Baraut, Vincent; Dailly, Olivier; Kapoula, Zoï

2016-01-01

Performance of the vestibular, visual, and somatosensory systems decreases with age, reducing the capacity of postural control, and increasing the risk of falling. The purpose of this study is to measure the effects of vision, active vergence eye movements, viewing distance/vergence angle and a simple cognitive task on postural control during an upright stance, in completely autonomous elderly individuals. Participated in the study, 23 elderly subjects (73.4 ± 6.8 years) who were enrolled in a center dedicated to the prevention of falling. Their body oscillations were measured with the DynaPort(®) device, with three accelerometers, placed at the lumbosacral level, near the center of mass. The conditions were the following: eyes open fixating on LED at 20 cm or 150 cm (vergence angle 17.0° and 2.3° respectively) with or without additional cognitive tasks (counting down from one hundred), performing active vergence by alternating the fixation between the far and the near LED (convergence and divergence), eyes closed after having fixated the far LED. The results showed that the postural stability significantly decreased when fixating on the LED at a far distance (weak convergence angle) with or without cognitive tasks; active convergence-divergence between the LEDs improved the postural stability while eye closure decreased it. The privilege of proximity (with increased convergence at near), previously established with foot posturography, is shown here to be valid for accelerometry with the center of mass in elderly. Another major result is the beneficial contribution of active vergence eye movements to better postural stability. The results bring new perspectives for the role of eye movement training to preserve postural control and autonomy in elderly. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Using the systems framework for postural control to analyze the components of balance evaluated in standardized balance measures: a scoping review.

PubMed

Sibley, Kathryn M; Beauchamp, Marla K; Van Ooteghem, Karen; Straus, Sharon E; Jaglal, Susan B

2015-01-01

To identify components of postural control included in standardized balance measures for adult populations. Electronic searches of MEDLINE, EMBASE, and CINAHL databases using keyword combinations of postural balance/equilibrium, psychometrics/reproducibility of results/predictive value of tests/validation studies, instrument construction/instrument validation, geriatric assessment/disability evaluation, gray literature, and hand searches. Inclusion criteria were measures with a stated objective to assess balance, adult populations (18y and older), at least 1 psychometric evaluation, 1 standing task, a standardized protocol and evaluation criteria, and published in English. Two reviewers independently identified studies for inclusion. Sixty-six measures were included. A research assistant extracted descriptive characteristics and 2 reviewers independently coded components of balance in each measure using the Systems Framework for Postural Control, a widely recognized model of balance. Components of balance evaluated in these measures were underlying motor systems (100% of measures), anticipatory postural control (71%), dynamic stability (67%), static stability (64%), sensory integration (48%), functional stability limits (27%), reactive postural control (23%), cognitive influences (17%), and verticality (8%). Thirty-four measures evaluated 3 or fewer components of balance, and 1 measure-the Balance Evaluation Systems Test-evaluated all components of balance. Several standardized balance measures provide only partial information on postural control and omit important components of balance related to avoiding falls. As such, the choice of measure(s) may limit the overall interpretation of an individual's balance ability. Continued work is necessary to increase the implementation of comprehensive balance assessment in research and practice. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Can an anti-gravity treadmill improve stability of children with cerebral palsy?

PubMed

Birgani, P M; Ashtiyani, M; Rasooli, A; Shahrokhnia, M; Shahrokhi, A; Mirbagheri, M M

2016-08-01

We aimed to study the effects of an anti-gravity treadmill (AlterG) training on balance and postural stability in children with cerebral palsy (CP). AlterG training was performed 3 days/week for 8 weeks, with up to 45 minutes of training per session. The subject was evaluated before and after the 8-week training. The effects of training on the balance and postural stability was evaluated based on the Romberg test that was performed by using a posturography device. The parameters quantifying Center-of-Pressure (CoP) were calculated using different analytical approaches including power spectral density and principal components analyses. All of the key parameters including the Stabilogram, the Fast Fourier Transform (FFT) Energy, the Eigenvectors, and the Eigenvalues of CoP were modified between 14%-84%. The results indicated that the balance features were improved substantially after training. The clinical implication is that the AlterG has the potential to effectively improve postural stability in children with cerebral palsy.

Canoe game-based virtual reality training to improve trunk postural stability, balance, and upper limb motor function in subacute stroke patients: a randomized controlled pilot study.

PubMed

Lee, Myung-Mo; Shin, Doo-Chul; Song, Chang-Ho

2016-07-01

[Purpose] This study was aimed at investigating the preliminary therapeutic efficacy and usefulness of canoe game-based virtual reality training for stroke patients. [Subjects and Methods] Ten stroke patients were randomly assigned to an experimental group (EG; n=5) or a control group (CG; n=5). Patients in both groups participated in a conventional rehabilitation program, but those in the EG additionally participated in a 30-min canoe game-based virtual reality training program 3 days a week for 4 weeks. Therapeutic efficacy was assessed based on trunk postural stability, balance, and upper limb motor function. In addition, the usefulness of canoe game-based virtual reality training was assessed in the EG and therapist group (TG; n=20), which consisted of physical and occupational therapists, by using the System Usability Scale (SUS). [Results] Improvements in trunk postural stability, balance, and upper limb motor function were observed in the EG and CG, but were greater in the EG. The mean SUS scores in the EG and TG were 71 ± 5.2 and 74.2 ± 4.8, respectively. [Conclusion] Canoe game-based virtual reality training is an acceptable and effective intervention for improving trunk postural stability, balance, and upper limb motor function in stroke patients.

Feet deformities are correlated with impaired balance and postural stability in seniors over 75

PubMed Central

Puszczalowska-Lizis, Ewa; Bujas, Przemyslaw; Omorczyk, Jaroslaw; Jandzis, Slawomir

2017-01-01

Objective Understanding the factors and mechanisms that determine balance in seniors appears vital in terms of their self-reliance and overall safety. The study aimed to determine the relationship between the features of feet structure and the indicators of postural stability in the elderly. Methods The study group comprised 80 seniors (41F, 39M; aged 75–85 years). CQ-ST podoscope and the CQ-Stab 2P two-platform posturograph were used as primary research tools. The data were analyzed based on Spearman’s rank correlation and forward stepwise regression. Results Analysis of forward stepwise regression identified the left foot length in females and Clarke’s angle of the left foot in men as significant and independent predictors of postural up to 30% of the variance of dependent variables. Conclusions Longer feet provide older women with better stability, whereas in men, the lowering of the longitudinal arch results in postural deterioration. In the elderly, the left lower limb shows greater activity in the stabilizing processes in the standing position than the right one. In gerontological rehabilitation special attention should be paid to the individually tailored, gender-specific treatment, with a view to enhancing overall safety and quality of seniors’ lives. PMID:28877185

Gaze and viewing angle influence visual stabilization of upright posture

PubMed Central

Ustinova, KI; Perkins, J

2011-01-01

Focusing gaze on a target helps stabilize upright posture. We investigated how this visual stabilization can be affected by observing a target presented under different gaze and viewing angles. In a series of 10-second trials, participants (N = 20, 29.3 ± 9 years of age) stood on a force plate and fixed their gaze on a figure presented on a screen at a distance of 1 m. The figure changed position (gaze angle: eye level (0°), 25° up or down), vertical body orientation (viewing angle: at eye level but rotated 25° as if leaning toward or away from the participant), or both (gaze and viewing angle: 25° up or down with the rotation equivalent of a natural visual perspective). Amplitude of participants’ sagittal displacement, surface area, and angular position of the center of gravity (COG) were compared. Results showed decreased COG velocity and amplitude for up and down gaze angles. Changes in viewing angles resulted in altered body alignment and increased amplitude of COG displacement. No significant changes in postural stability were observed when both gaze and viewing angles were altered. Results suggest that both the gaze angle and viewing perspective may be essential variables of the visuomotor system modulating postural responses. PMID:22398978

Validity of the Instrumented Push and Release Test to Quantify Postural Responses in Persons With Multiple Sclerosis.

PubMed

El-Gohary, Mahmoud; Peterson, Daniel; Gera, Geetanjali; Horak, Fay B; Huisinga, Jessie M

2017-07-01

To test the validity of wearable inertial sensors to provide objective measures of postural stepping responses to the push and release clinical test in people with multiple sclerosis. Cross-sectional study. University medical center balance disorder laboratory. Total sample N=73; persons with multiple sclerosis (PwMS) n=52; healthy controls n=21. Stepping latency, time and number of steps required to reach stability, and initial step length were calculated using 3 inertial measurement units placed on participants' lumbar spine and feet. Correlations between inertial sensor measures and measures obtained from the laboratory-based systems were moderate to strong and statistically significant for all variables: time to release (r=.992), latency (r=.655), time to stability (r=.847), time of first heel strike (r=.665), number of steps (r=.825), and first step length (r=.592). Compared with healthy controls, PwMS demonstrated a longer time to stability and required a larger number of steps to reach stability. The instrumented push and release test is a valid measure of postural responses in PwMS and could be used as a clinical outcome measures for patient care decisions or for clinical trials aimed at improving postural control in PwMS. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Cognitive tasks promote automatization of postural control in young and older adults.

PubMed

Potvin-Desrochers, Alexandra; Richer, Natalie; Lajoie, Yves

2017-09-01

Researchers looking at the effects of performing a concurrent cognitive task on postural control in young and older adults using traditional center-of-pressure measures and complexity measures found discordant results. Results of experiments showing improvements of stability have suggested the use of strategies such as automatization of postural control or stiffening strategy. This experiment aimed to confirm in healthy young and older adults that performing a cognitive task while standing leads to improvements that are due to automaticity of sway by using sample entropy. Twenty-one young adults and twenty-five older adults were asked to stand on a force platform while performing a cognitive task. There were four cognitive tasks: simple reaction time, go/no-go reaction time, equation and occurrence of a digit in a number sequence. Results demonstrated decreased sway area and variability as well as increased sample entropy for both groups when performing a cognitive task. Results suggest that performing a concurrent cognitive task promotes the adoption of an automatic postural control in young and older adults as evidenced by an increased postural stability and postural sway complexity. Copyright © 2017 Elsevier B.V. All rights reserved.

The effects of shoulder stabilization exercises and pectoralis minor stretching on balance and maximal shoulder muscle strength of healthy young adults with round shoulder posture.

PubMed

Kim, Mi-Kyoung; Lee, Jung Chul; Yoo, Kyung-Tae

2018-03-01

[Purpose] The purpose of this study was to analyze the effects of pectoralis minor stretching and shoulder strengthening with an elastic band on balance and maximal shoulder muscle strength in young adults with rounded shoulder posture. [Subjects and Methods] Nineteen subjects with rounded shoulder posture were randomly divided into 2 groups: a shoulder stabilization exercise group and a stretching exercise group. The groups performed each exercise for 40 minutes, 3 times a week, for 4 weeks. Static balance (eyes open and closed), dynamic balance (the limits of stability in 4 directions) and shoulder muscle strength in 5 directions were measure before and after the exercises. [Results] The stretching exercise demonstrated a significant difference between the pre- and post-exercise in the static balance with eyes closed and extension and horizontal abduction strength while the stabilization exercise demonstrated significant difference in the left and right directions between the pre- and post-exercise of the dynamic balance and flexion strength. The stabilization exercise demonstrated significant differences shown in the flexion between the pre- and post-test. [Conclusion] The shoulder stabilization and stretching exercises improved the static balance, dynamic balance, and muscle strength.

Postural Consequences of Cervical Sagittal Imbalance: A Novel Laboratory Model.

PubMed

Patwardhan, Avinash G; Havey, Robert M; Khayatzadeh, Saeed; Muriuki, Muturi G; Voronov, Leonard I; Carandang, Gerard; Nguyen, Ngoc-Lam; Ghanayem, Alexander J; Schuit, Dale; Patel, Alpesh A; Smith, Zachary A; Sears, William

2015-06-01

A biomechanical study using human spine specimens. To study postural compensations in lordosis angles that are necessary to maintain horizontal gaze in the presence of forward head posture and increasing T1 sagittal tilt. Forward head posture relative to the shoulders, assessed radiographically using the horizontal offset distance between the C2 and C7 vertebral bodies (C2-C7 [sagittal vertical alignment] SVA), is a measure of global cervical imbalance. This may result from kyphotic alignment of cervical segments, muscle imbalance, as well as malalignment of thoracolumbar spine. Ten cadaveric cervical spines (occiput-T1) were tested. The T1 vertebra was anchored to a tilting and translating base. The occiput was free to move vertically but its angular orientation was constrained to ensure horizontal gaze regardless of sagittal imbalance. A 5-kg mass was attached to the occiput to mimic head weight. Forward head posture magnitude and T1 tilt were varied and motions of individual vertebrae were measured to calculate C2-C7 SVA and lordosis across C0-C2 and C2-C7. Increasing C2-C7 SVA caused flexion of lower cervical (C2-C7) segments and hyperextension of suboccipital (C0-C1-C2) segments to maintain horizontal gaze. Increasing kyphotic T1 tilt primarily increased lordosis across the C2-C7 segments. Regression models were developed to predict the compensatory C0-C2 and C2-C7 angulation needed to maintain horizontal gaze given values of C2-C7 SVA and T1 tilt. This study established predictive relationships between radiographical measures of forward head posture, T1 tilt, and postural compensations in the cervical lordosis angles needed to maintain horizontal gaze. The laboratory model predicted that normalization of C2-C7 SVA will reduce suboccipital (C0-C2) hyperextension, whereas T1 tilt reduction will reduce the hyperextension in the C2-C7 segments. The predictive relationships may help in planning corrective strategy in patients experiencing neck pain, which may be attributed to sagittal malalignment. N/A.

Influence of visual inputs on quasi-static standing postural steadiness in individuals with spinal cord injury.

PubMed

Lemay, Jean-François; Gagnon, Dany; Duclos, Cyril; Grangeon, Murielle; Gauthier, Cindy; Nadeau, Sylvie

2013-06-01

Postural steadiness while standing is impaired in individuals with spinal cord injury (SCI) and could be potentially associated with increased reliance on visual inputs. The purpose of this study was to compare individuals with SCI and able-bodied participants on their use of visual inputs to maintain standing postural steadiness. Another aim was to quantify the association between visual contribution to achieve postural steadiness and a clinical balance scale. Individuals with SCI (n = 15) and able-bodied controls (n = 14) performed quasi-static stance, with eyes open or closed, on force plates for two 45 s trials. Measurements of the centre of pressure (COP) included the mean value of the root mean square (RMS), mean COP velocity (MV) and COP sway area (SA). Individuals with SCI were also evaluated with the Mini-Balance Evaluation Systems Test (Mini BESTest), a clinical outcome measure of postural steadiness. Individuals with SCI were significantly less stable than able-bodied controls in both conditions. The Romberg ratios (eyes open/eyes closed) for COP MV and SA were significantly higher for individuals with SCI, indicating a higher contribution of visual inputs for postural steadiness in that population. Romberg ratios for RMS and SA were significantly associated with the Mini-BESTest. This study highlights the contribution of visual inputs in individuals with SCI when maintaining quasi-static standing posture. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of postural control and maturation of sensory systems in children of different ages a cross-sectional study.

PubMed

Sá, Cristina Dos Santos Cardoso de; Boffino, Catarina Costa; Ramos, Renato Teodoro; Tanaka, Clarice

To evaluate the stability, postural adjustments and contributions of sensory information for postural control in children. 40 boys and 40 girls were equally divided into groups of 5, 7, 9 and 12 years (G5, G7, G9 and G12). All children were submitted to dynamic posturography using a modified sensory organization test, using four sensory conditions: combining stable or sway referencing platform with eyes opened, or closed. The area and displacements of the center of pressure were used to determine stability, while the adjustments were used to measure the speed of the center of pressure displacements. These measurements were compared between groups and test conditions. Stability tends to increase with age and to decrease with sensory manipulation with significant differences between G5 and G7 in different measures. G7 differed from G12 under the conditions of stable and sway platform with eyes open. G9 did not differ from G12. Similar behavior was observed for adjustments, especially in anterior-posterior directions. Postural stability and adjustments were associated with age and were influenced by sensory manipulation. The ability to perform anterior-posterior adjustments was more evident and sensory maturation occurred firstly on the visual system, then proprioceptive system, and finally, the vestibular system, reaching functional maturity at nine years of age. Seven-year-olds seem to go through a period of differentiated singularity in postural control. Copyright © 2017 Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. Publicado por Elsevier Editora Ltda. All rights reserved.

Postural Instability Caused by Extended Bed Rest Is Alleviated by Brief Daily Exposure to Low Magnitude Mechanical Signals

PubMed Central

Muir, Jesse; Judex, Stefan; Qin, Yi-Xian; Rubin, Clinton

2011-01-01

Loss of postural stability, as exacerbated by chronic bed rest, aging, neuromuscular injury or disease, results in a marked increase in the risk of falls, potentiating severe injury and even death. To investigate the capacity of low magnitude mechanical signals (LMMS) to retain postural stability under conditions conducive to its decline, twenty-nine healthy adult subjects underwent 90 days of 6-degree head down tilt bed-rest. Treated subjects underwent a daily 10 minute regimen of 30 Hz LMMS at either a 0.3g-force (n=12) or 0.5g force (n=5). Control subjects (n=13) received no LMMS treatment. Postural stability, quantified by dispersions of the plantar-based center of pressure, deteriorated significantly from baseline in control subjects, with displacement and velocity at 60d increasing 98.7% and 193% respectively, while the LMMS group increased only 26.7% and 6.4%, reflecting a 73% and 97% relative retention in stability as compared to control. Increasing LMMS magnitude from 0.3 to 0.5g had no significant influence on outcomes. LMMS failed to spare loss of muscle extension strength, but helped to retain flexion strength (e.g., 46.2% improved retention of baseline concentric flexion strength vs. untreated controls; p=0.01). These data suggest the potential of extremely small mechanical signals as a non-invasive means of preserving postural control under the challenge of chronic bed rest, and may ultimately represent non-pharmacologic means of reducing the risk of debilitating falls in elderly and infirm. PMID:21273076

A new methodology based on functional principal component analysis to study postural stability post-stroke.

PubMed

Sánchez-Sánchez, M Luz; Belda-Lois, Juan-Manuel; Mena-Del Horno, Silvia; Viosca-Herrero, Enrique; Igual-Camacho, Celedonia; Gisbert-Morant, Beatriz

2018-05-05

A major goal in stroke rehabilitation is the establishment of more effective physical therapy techniques to recover postural stability. Functional Principal Component Analysis provides greater insight into recovery trends. However, when missing values exist, obtaining functional data presents some difficulties. The purpose of this study was to reveal an alternative technique for obtaining the Functional Principal Components without requiring the conversion to functional data beforehand and to investigate this methodology to determine the effect of specific physical therapy techniques in balance recovery trends in elderly subjects with hemiplegia post-stroke. A randomized controlled pilot trial was developed. Thirty inpatients post-stroke were included. Control and target groups were treated with the same conventional physical therapy protocol based on functional criteria, but specific techniques were added to the target group depending on the subjects' functional level. Postural stability during standing was quantified by posturography. The assessments were performed once a month from the moment the participants were able to stand up to six months post-stroke. The target group showed a significant improvement in postural control recovery trend six months after stroke that was not present in the control group. Some of the assessed parameters revealed significant differences between treatment groups (P < 0.05). The proposed methodology allows Functional Principal Component Analysis to be performed when data is scarce. Moreover, it allowed the dynamics of recovery of two different treatment groups to be determined, showing that the techniques added in the target group increased postural stability compared to the base protocol. Copyright © 2018 Elsevier Ltd. All rights reserved.

Assessing postural stability via the correlation patterns of vertical ground reaction force components.

PubMed

Hong, Chih-Yuan; Guo, Lan-Yuen; Song, Rong; Nagurka, Mark L; Sung, Jia-Li; Yen, Chen-Wen

2016-08-02

Many methods have been proposed to assess the stability of human postural balance by using a force plate. While most of these approaches characterize postural stability by extracting features from the trajectory of the center of pressure (COP), this work develops stability measures derived from components of the ground reaction force (GRF). In comparison with previous GRF-based approaches that extract stability features from the GRF resultant force, this study proposes three feature sets derived from the correlation patterns among the vertical GRF (VGRF) components. The first and second feature sets quantitatively assess the strength and changing speed of the correlation patterns, respectively. The third feature set is used to quantify the stabilizing effect of the GRF coordination patterns on the COP. In addition to experimentally demonstrating the reliability of the proposed features, the efficacy of the proposed features has also been tested by using them to classify two age groups (18-24 and 65-73 years) in quiet standing. The experimental results show that the proposed features are considerably more sensitive to aging than one of the most effective conventional COP features and two recently proposed COM features. By extracting information from the correlation patterns of the VGRF components, this study proposes three sets of features to assess human postural stability during quiet standing. As demonstrated by the experimental results, the proposed features are not only robust to inter-trial variability but also more accurate than the tested COP and COM features in classifying the older and younger age groups. An additional advantage of the proposed approach is that it reduces the force sensing requirement from 3D to 1D, substantially reducing the cost of the force plate measurement system.

Postural stability is compromised by fatiguing overhead work.

PubMed

Nussbaum, Maury A

2003-01-01

In a laboratory setting, 16 participants performed a repetitive overhead tapping task for 3 hours or until self-terminated due to substantial shoulder discomfort. Several measures of postural sway and stability were obtained using a force plate, both during quiet standing and during performance of the tapping task. Sway area and peak sway velocity showed consistent increases with time, whereas changes in average velocity and peak whole-body center-of-mass acceleration were either small or nonsignificant. Although relatively insensitive to several task variables, changes in sway areas and peak velocities were substantially larger in trials terminated by the participants. It is argued that fatigue plays a more important role than simple task duration in causing the observed increases in sway, and hence decreases in postural stability. Potential whole-body consequences of localized musculoskeletal stresses appear supported by the results, and implications for safety, risks of falls, and work scheduling are discussed.

Optimal coordination and control of posture and movements.

PubMed

Johansson, Rolf; Fransson, Per-Anders; Magnusson, Måns

2009-01-01

This paper presents a theoretical model of stability and coordination of posture and locomotion, together with algorithms for continuous-time quadratic optimization of motion control. Explicit solutions to the Hamilton-Jacobi equation for optimal control of rigid-body motion are obtained by solving an algebraic matrix equation. The stability is investigated with Lyapunov function theory and it is shown that global asymptotic stability holds. It is also shown how optimal control and adaptive control may act in concert in the case of unknown or uncertain system parameters. The solution describes motion strategies of minimum effort and variance. The proposed optimal control is formulated to be suitable as a posture and movement model for experimental validation and verification. The combination of adaptive and optimal control makes this algorithm a candidate for coordination and control of functional neuromuscular stimulation as well as of prostheses. Validation examples with experimental data are provided.

Space flight and changes in spatial orientation

NASA Technical Reports Server (NTRS)

Reschke, Millard F.; Bloomberg, Jacob J.; Harm, Deborah L.; Paloski, William H.

1992-01-01

From a sensory point of view, space flight represents a form of stimulus rearrangement requiring modification of established terrestrial response patterns through central reinterpretation. Evidence of sensory reinterpretation is manifested as postflight modifications of eye/head coordination, locomotor patterns, postural control strategies, and illusory perceptions of self or surround motion in conjunction with head movements. Under normal preflight conditions, the head is stabilized during locomotion, but immediately postflight reduced head stability, coupled with inappropriate eye/head coordination, results in modifications of gait. Postflight postural control exhibits increased dependence on vision which compensates for inappropriate interpretation of otolith and proprioceptive inputs. Eye movements compensatory for perceived self motion, rather than actual head movements have been observed postflight. Overall, the in-flight adaptive modification of head stabilization strategies, changes in head/eye coordination, illusionary motion, and postural control are maladaptive for a return to the terrestrial environment. Appropriate countermeasures for long-duration flights will rely on preflight adaptation and in-flight training.

Development of low postural tone compensatory patterns in children - theoretical basis.

PubMed

Gogola, Anna; Saulicz, Edward; Kuszewski, Michał; Matyja, Małgorzata; Myśliwiec, Andrzej

2014-01-01

Neurological literature indicates the existence of children with low postural tone without association with central nervous system damage. This fact induces to think about mechanisms, which allow these children to maintain upright posture. There is a suspicion that compensatory mechanism included in this process, enables to achieve upright posture, but at expense of body posture quality. Observations of children's developmental stages caused determination of some postural tone area, which comprise both children with normotonia and with low postural tone without characteristics of central nervous system (CNS) damage. Set of specific qualities allows determination of two types of low postural tone: spastoidal and atetoidal type. Spastoidal type is characterized by deep trunk muscles (local) low postural tone compensated by excessive tension of superficial muscles (global). Atetoidal type includes children with low postural tone in both deep and superficial muscles. At inefficient active subsystem, verticalization proceeds at excessive use of passive subsystem qualities, that is meniscus, ligament, bone shape, and muscles passive features. From neurodevelopmental point of view compensatory mechanisms can be used in children with low postural tone in order to achieve upright posture, but at expense of body posture quality.

Postural control and ventilatory drive during voluntary hyperventilation and carbon dioxide rebreathing.

PubMed

David, Pascal; Laval, David; Terrien, Jérémy; Petitjean, Michel

2012-01-01

The present study sought to establish links between hyperventilation and postural stability. Eight university students were asked to stand upright under two hyperventilation conditions applied randomly: (1) a metabolic hyperventilation induced by 5 min of hypercapnic-hyperoxic rebreathing (CO(2)-R); and, (2) a voluntary hyperventilation (VH) of 3 min imposed by a metronome set at 25 cycles per min. Recordings were obtained with eyes open, with the subjects standing on a force plate over 20-s periods. Ventilatory response, displacements in the centre of pressure in both the frontal and sagittal planes and fluctuations in the three planes of the ground reaction force were monitored in the time and frequency domains. Postural changes related to respiratory variations were quantified by coherence analysis. Myoelectric activities of the calf muscles were recorded using surface electromyography. Force plate measurements revealed a reduction in postural stability during both CO(2)-R and VH conditions, mainly in the sagittal plane. Coherence analysis provided evidence of a ventilatory origin in the vertical ground reaction force fluctuations during VH. Electromyographic analyses showed different leg muscles strategies, assuming the existence of links between the control of respiration and the control of posture. Our results suggest that the greater disturbing effects caused by voluntary hyperventilation on body balance are more compensated when respiration is under automatic control. These findings may have implications for understanding the organisation of postural and respiratory activities and suggest that stability of the body may be compromised in situations in which respiratory demand increases and requires voluntary control.

Postural stability and the influence of concurrent muscle activation--Beneficial effects of jaw and fist clenching.

PubMed

Ringhof, Steffen; Leibold, Timo; Hellmann, Daniel; Stein, Thorsten

2015-10-01

Recent studies reported on the potential benefits of submaximum clenching of the jaw on human postural control in upright unperturbed stance. However, it remained unclear whether these effects might also be observed among active controls. The purpose of the present study, therefore, was to comparatively examine the influence of concurrent muscle activation in terms of submaximum clenching of the jaw and submaximum clenching of the fists on postural stability. Posturographic analyses were conducted with 17 healthy young adults on firm and foam surfaces while either clenching the jaw (JAW) or clenching the fists (FIST), whereas habitual standing served as the control condition (CON). Both submaximum tasks were performed at 25% maximum voluntary contraction, assessed, and visualized in real time by means of electromyography. Statistical analyses revealed that center of pressure (COP) displacements were significantly reduced during JAW and FIST, but with no differences between both concurrent clenching activities. Further, a significant increase in COP displacements was observed for the foam as compared to the firm condition. The results showed that concurrent muscle activation significantly improved postural stability compared with habitual standing, and thus emphasize the beneficial effects of jaw and fist clenching for static postural control. It is suggested that concurrent activities contribute to the facilitation of human motor excitability, finally increasing the neural drive to the distal muscles. Future studies should evaluate whether elderly or patients with compromised postural control might benefit from these physiological responses, e.g., in the form of a reduced risk of falling. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of different foot progression angles and platform settings on postural stability and fall risk in healthy and medial knee osteoarthritic adults.

PubMed

Khan, Saad Jawaid; Khan, Soobia Saad; Usman, Juliana; Mokhtar, Abdul Halim; Abu Osman, Noor Azuan

2018-02-01

This study aims to investigate the effects of varying toe angles at different platform settings on Overall Stability Index of postural stability and fall risk using Biodex Balance System in healthy participants and medial knee osteoarthritis patients. Biodex Balance System was employed to measure postural stability and fall risk at different foot progression angles (ranging from -20° to 40°, with 10° increments) on 20 healthy (control group) and 20 knee osteoarthritis patients (osteoarthritis group) randomly (age: 59.50 ± 7.33 years and 61.50 ± 8.63 years; body mass: 69.95 ± 9.86 kg and 70.45 ± 8.80 kg). Platform settings used were (1) static, (2) postural stability dynamic level 8 (PS8), (3) fall risk levels 12 to 8 (FR12) and (4) fall risk levels 8 to 2 (FR8). Data from the tests were analysed using three-way mixed repeated measures analysis of variance. The participant group, platform settings and toe angles all had a significant main effect on balance ( p ≤ 0.02). Platform settings had a significant interaction effect with participant group F(3, 144) = 6.97, p < 0.01 and toe angles F(21, 798) = 2.83, p < 0.01. Non-significant interactions were found for group × toe angles, F(7, 266) = 0.89, p = 0.50, and for group × toe angles × settings, F(21, 798) = 1.07, p = 0.36. The medial knee osteoarthritis group has a poorer postural stability and increased fall risk as compared to the healthy group. Changing platform settings has a more pronounced effect on balance in knee osteoarthritis group than in healthy participants. Changing toe angles produced similar effects in both the participant groups, with decreased stability and increased fall risk at extreme toe-in and toe-out angles.

Effects of Pilates exercises on sensory interaction, postural control and fatigue in patients with multiple sclerosis.

PubMed

Soysal Tomruk, Melda; Uz, Muhammed Zahid; Kara, Bilge; İdiman, Egemen

2016-05-01

Decreased postural control, sensory integration deficits and fatigue are important problems that cause functional impairments in patients with multiple sclerosis (pwMS). To examine the effect of modified clinical Pilates exercises on sensory interaction and balance, postural control and fatigue in pwMS. Eleven patients with multiple sclerosis and 12 healthy matched controls were recruited in this study. Limits of stability and postural stability tests were used to evaluate postural control by Biodex Balance System and sensory interaction assessed. Fatigue was assessed by Modified Fatigue Impact Scale. Pilates exercises were applied two times a week for 10 weeks and measurements were repeated to pwMS after exercise training. Postural control and fatigue (except psychosocial parameter) of pwMS were significantly worser than healthy controls (p<0.05). Significant improvements occurred in sensory interaction (eyes open, foam surface) and total, physical and cognitive scores of fatigue after 10-week modified clinical Pilates training (p<0.05). No significant changes were detected in postural control after the pilates exercises (p>0.05). Ten-week Pilates training is effective to improve sensory interaction and to decrease fatigue. Pilates exercises can be applied safely in ambulatory pwMS for enhance sensory interaction and balance and combat fatigue. More investigations are needed. Copyright © 2016 Elsevier B.V. All rights reserved.

Specificity of learning: why infants fall over a veritable cliff.

PubMed

Adolph, K E

2000-07-01

Nine-month-old infants were tested at the precipice of safe and risky gaps in the surface of support. Their reaching and avoidance responses were compared in two postures, an experienced sitting posture and a less familiar crawling posture. The babies avoided reaching over risky gaps in the sitting posture but fell into risky gaps while attempting to reach in the crawling posture. This dissociation between developmental changes in posture suggests that (a) each postural milestone represents a different, modularly organized control system and (b) infants' adaptive avoidance responses are based on information about their postural stability relative to the gap size. Moreover, the results belie previous accounts suggesting that avoidance of a disparity in depth of the ground surface depends on general knowledge such as fear of heights, associations between depth information and falling, or knowledge that the body cannot be supported in empty space.

Effects of deep breathing on internal oblique and multifidus muscle activity in three sitting postures

PubMed Central

Ko, Min-Joo; Jung, Eun-Joo; Kim, Moon-Hwan; Oh, Jae-Seop

2018-01-01

[Purpose] This study was to investigate differences in the level of activity of the external oblique (EO), internal oblique (IO), and multifidus (MF) muscles with deep breathing in three sitting postures. [Subjects and Methods] Sixteen healthy women were recruited. The muscle activity (EO, IO, MF) of all subjects was measured in three sitting postures (slumped, thoracic upright, and lumbo-pelvic upright sitting postures) using surface electromyography. The activity of the same muscles was then remeasured in the three sitting postures during deep breathing. [Results] Deep breathing significantly increased activity in the EO, IO, and MF compared with normal breathing. Comparing postures, the activity of the MF and IO muscles was highest in the lumbo-pelvic upright sitting posture. [Conclusion] An lumbo-pelvic upright sitting posture with deep breathing could increase IO and MF muscle activity, thus improving lumbo-pelvic region stability. PMID:29706695

Neural Correlates of Task Cost for Stance Control with an Additional Motor Task: Phase-Locked Electroencephalogram Responses

PubMed Central

Hwang, Ing-Shiou; Huang, Cheng-Ya

2016-01-01

With appropriate reallocation of central resources, the ability to maintain an erect posture is not necessarily degraded by a concurrent motor task. This study investigated the neural control of a particular postural-suprapostural procedure involving brain mechanisms to solve crosstalk between posture and motor subtasks. Participants completed a single posture task and a dual-task while concurrently conducting force-matching and maintaining a tilted stabilometer stance at a target angle. Stabilometer movements and event-related potentials (ERPs) were recorded. The added force-matching task increased the irregularity of postural response rather than the size of postural response prior to force-matching. In addition, the added force-matching task during stabilometer stance led to marked topographic ERP modulation, with greater P2 positivity in the frontal and sensorimotor-parietal areas of the N1-P2 transitional phase and in the sensorimotor-parietal area of the late P2 phase. The time-frequency distribution of the ERP primary principal component revealed that the dual-task condition manifested more pronounced delta (1–4 Hz) and beta (13–35 Hz) synchronizations but suppressed theta activity (4–8 Hz) before force-matching. The dual-task condition also manifested coherent fronto-parietal delta activity in the P2 period. In addition to a decrease in postural regularity, this study reveals spatio-temporal and temporal-spectral reorganizations of ERPs in the fronto-sensorimotor-parietal network due to the added suprapostural motor task. For a particular set of postural-suprapostural task, the behavior and neural data suggest a facilitatory role of autonomous postural response and central resource expansion with increasing interregional interactions for task-shift and planning the motor-suprapostural task. PMID:27010634

Pain relief is associated with decreasing postural sway in patients with non-specific low back pain.

PubMed

Ruhe, Alexander; Fejer, René; Walker, Bruce

2012-03-21

Increased postural sway is well documented in patients suffering from non-specific low back pain, whereby a linear relationship between higher pain intensities and increasing postural sway has been described. No investigation has been conducted to evaluate whether this relationship is maintained if pain levels change in adults with non-specific low back pain. Thirty-eight patients with non-specific low back pain and a matching number of healthy controls were enrolled. Postural sway was measured by three identical static bipedal standing tasks of 90 sec duration with eyes closed in narrow stance on a firm surface. The perceived pain intensity was assessed by a numeric rating scale (NRS-11). The patients received three manual interventions (e.g. manipulation, mobilization or soft tissue techniques) at 3-4 day intervals, postural sway measures were obtained at each occasion. A clinically relevant decrease of four NRS scores in associated with manual interventions correlated with a significant decrease in postural sway. In contrast, if no clinically relevant change in intensity occurred (≤ 1 level), postural sway remained similar compared to baseline. The postural sway measures obtained at follow-up sessions 2 and 3 associated with specific NRS level showed no significant differences compared to reference values for the same pain score. Alterations in self-reported pain intensities are closely related to changes in postural sway. The previously reported linear relationship between the two variables is maintained as pain levels change. Pain interference appears responsible for the altered sway in pain sufferers. This underlines the clinical use of sway measures as an objective monitoring tool during treatment or rehabilitation.

Sit Up Straight! It's Good Physics

ERIC Educational Resources Information Center

Colicchia, Giuseppe

2005-01-01

A simplified model has been developed that shows forces and torques involved in maintaining static posture in the cervical spine. The model provides a biomechanical basis to estimate loadings on the cervical discs under various postures. Thus it makes a biological context for teaching statics.

Posture, head stability, and orientation recovery during vestibular regeneration in pigeons.

PubMed

Dickman, J David; Lim, Insook

2004-09-01

Compensatory behavior such as oculomotor, gaze, and postural responses that occur during movement largely depend upon a functioning vestibular system. In the present study, the initial loss and subsequent recovery of postural and head stability in pigeons undergoing vestibular regeneration were examined. Adult pigeons were trained to manipulate a straight run chamber to peck an illuminated key for fluid reward. Six behavioral measures assessing performance, posture, and head stability were quantified. These included run latency, steps (walking), path negotiation (lane changes), gaze saccades, head bobs, and head shakes. Once normative values were obtained for four birds, complete lesion of all receptor cells and denervation of the epithelia in the vestibular endorgans were produced using a single intralabyrinthine application of streptomycin sulfate. Each bird was then tested at specific times during regeneration and the same behavioral measures examined. At 7 days post-streptomycin treatment (PST), all birds exhibited severe postural and head instability, with tremors, head shakes, staggering, and circling predominating. No normal trial runs, walking, gaze saccades, or head bobs were present. Many of these dysfunctions persisted through 3-4 weeks PST. Gradually, tremor and head shakes diminished and were replaced with an increasing number of normal head bobs during steps and gaze saccades. Beginning at 4 weeks PST, but largely inaccurate, was the observed initiation of directed steps, less staggering, and some successful path negotiation. As regeneration progressed, spatial orientation and navigation ability increased and, by 49 days PST, most trials were successful. By 70 days PST, all birds had recovered to pretreatment levels. Thus, it was observed that ataxia must subside, coincident with normalized head and postural stability prior to the recovery of spatial orientation and path navigation recovery. Parallels in recovery were drawn to hair cell regeneration and afferent responsiveness, as inferred from present results and those in other investigations.

Leg extensor muscle strength, postural stability, and fear of falling after a 2-month home exercise program in women with severe knee joint osteoarthritis.

PubMed

Rätsepsoo, Monika; Gapeyeva, Helena; Sokk, Jelena; Ereline, Jaan; Haviko, Tiit; Pääsuke, Mati

2013-01-01

BACKGROUND AND OBJECTIVE. The aim of this study was to compare the leg extensor muscle strength, the postural stability, and the fear of falling in the women with severe knee joint osteoarthritis (OA) before and after a 2-month home exercise program (HEP). MATERIAL AND METHODS. In total, 17 women aged 46-72 years with late-stage knee joint OA scheduled for total knee arthroplasty participated in this study before and after the 2-month HEP with strengthening, stretching, balance, and step exercises. The isometric peak torque (PT) of the leg extensors and postural stability characteristics when standing on a firm or a foam surface for 30 seconds were recorded. The fear of falling and the pain intensity (VAS) were estimated. RESULTS. A significant increase in the PT and the PT-to-body weight (PT-to-BW) ratio of the involved leg as well as the bilateral PT and the PT-to-BW ratio was found after the 2-month HEP compared with the data before the HEP (P<0.05). The PT and the PT-to-BW ratio of the involved leg were significantly lower compared with the uninvolved leg before the HEP (P<0.05). The center of the pressure sway length (foam surface) decreased significantly after the HEP (P<0.05). Significant correlations were found between the PT of the involved leg and the bilateral PT and the fear of falling and between the PT of the involved leg and the postural sway (foam surface) before the HEP. CONCLUSIONS. After the 2-month HEP, the leg extensor muscle strength increased and the postural sway length on a foam surface decreased. The results indicate that the increased leg extensor muscle strength improves postural stability and diminishes the fear of falling in women with late-stage knee joint OA.

Continuous Cognitive Task Promotes Greater Postural Stability than an Internal or External Focus of Attention in Older Adults.

PubMed

Richer, Natalie; Polskaia, Nadia; Lajoie, Yves

2017-01-01

Background/Study Context: Recent evidence suggests that removing attention from postural control using either an external focus or a cognitive task will improve stability in healthy young adults. Due to increases in attentional requirements of upright stance in older adults, it is unclear if similar benefits would be observed in this population. The aim of the present study was to examine the effect of attentional focus and of a continuous cognitive task on postural control in older adults. Sixteen healthy older adults (71.9 ± 4.32 years) were asked to stand quietly on a force platform with feet together in three different conditions: internal focus (minimizing movement of the hips), external focus (minimizing movement of markers placed on the hips), and cognitive task (silently counting the occurrence of a single digit in a 3-digit number sequence). A one-way analysis of variance with repeated measures on condition was performed for each postural control measure. Hypotheses were partially supported because the cognitive task led to greater stability than both focus conditions, as evidenced by a smaller sway area (p < .01, η p 2 = .41), reduced sway variability (anterior-posterior: p = .001, η p 2 = .37; medial-lateral: p < .0001, η p 2 = .49), and higher mean power frequency in the anterior-posterior direction (p = .01, η p 2 = .78). However, no difference was observed between internal and external focus conditions. A continuous, attention-demanding cognitive task significantly improved stability in older adults compared with an internal or external focus of attention. This suggests that older adults were able to effectively allocate their attention away from postural control, allowing a more automatic type of control to operate. Future studies should investigate a variety of cognitive tasks to determine the degree of postural improvement that can be observed in older adults.

Fingertip touch improves postural stability in patients with peripheral neuropathy.

PubMed

Dickstein, R; Shupert, C L; Horak, F B

2001-12-01

The purpose of this work was to determine whether fingertip touch on a stable surface could improve postural stability during stance in subjects with somatosensory loss in the feet from diabetic peripheral neuropathy. The contribution of fingertip touch to postural stability was determined by comparing postural sway in three touch conditions (light, heavy and none) in eight patients and eight healthy control subjects who stood on two surfaces (firm or foam) with eyes open or closed. In the light touch condition, fingertip touch provided only somatosensory information because subjects exerted less than 1 N of force with their fingertip to a force plate, mounted on a vertical support. In the heavy touch condition, mechanical support was available because subjects transmitted as much force to the force plate as they wished. In the no touch condition, subjects held the right forefinger above the force plate. Antero-posterior (AP) and medio-lateral (ML) root mean square (RMS) of center of pressure (CoP) sway and trunk velocity were larger in subjects with somatosensory loss than in control subjects, especially when standing on the foam surface. The effects of light and heavy touch were similar in the somatosensory loss and control groups. Fingertip somatosensory input through light touch attenuated both AP and ML trunk velocity as much as heavy touch. Light touch also reduced CoP sway compared to no touch, although the decrease in CoP sway was less effective than with heavy touch, particularly on the foam surface. The forces that were applied to the touch plate during light touch preceded movements of the CoP, lending support to the suggestion of a feedforward mechanism in which fingertip inputs trigger the activation of postural muscles for controlling body sway. These results have clinical implications for understanding how patients with peripheral neuropathy may benefit from a cane for postural stability in stance.

Running stability is enhanced by a proximo-distal gradient in joint neuromechanical control.

PubMed

Daley, M A; Felix, G; Biewener, A A

2007-02-01

We currently know little about how animals achieve dynamic stability when running over uneven and unpredictable terrain, often characteristic of their natural environment. Here we investigate how limb and joint mechanics of an avian biped, the helmeted guinea fowl Numida meleagris, respond to an unexpected drop in terrain during running. In particular, we address how joint mechanics are coordinated to achieve whole limb dynamics. Based on muscle-tendon architecture and previous studies of steady and incline locomotion, we hypothesize a proximo-distal gradient in joint neuromechanical control. In this motor control strategy, (1) proximal muscles at the hip and knee joints are controlled primarily in a feedforward manner and exhibit load-insensitive mechanical performance, and (2) distal muscles at the ankle and tarsometatarso-phalangeal (TMP) joints are highly load-sensitive, due to intrinsic mechanical effects and rapid, higher gain proprioceptive feedback. Limb kinematics and kinetics during the unexpected perturbation reveal that limb retraction, controlled largely by the hip, remains similar to level running throughout the perturbed step, despite altered limb loading. Individual joints produce or absorb energy during both level and perturbed running steps, such that the net limb work depends on the balance of energy among the joints. The hip maintains the same mechanical role regardless of limb loading, whereas the ankle and TMP switch between spring-like or damping function depending on limb posture at ground contact. Initial knee angle sets limb posture and alters the balance of work among the joints, although the knee contributes little work itself. This distribution of joint function results in posture-dependent changes in work performance of the limb, which allow guinea fowl to rapidly produce or absorb energy in response to the perturbation. The results support the hypothesis that a proximo-distal gradient exists in limb neuromuscular performance and motor control. This control strategy allows limb cycling to remain constant, whereas limb posture, loading and energy performance are interdependent. We propose that this control strategy provides simple, rapid mechanisms for managing energy and controlling velocity when running over rough terrain.

Running stability is enhanced by a proximo-distal gradient in joint neuromechanical control

PubMed Central

Daley, M. A.; Felix, G.; Biewener, A. A.

2008-01-01

Summary We currently know little about how animals achieve dynamic stability when running over uneven and unpredictable terrain, often characteristic of their natural environment. Here we investigate how limb and joint mechanics of an avian biped, the helmeted guinea fowl Numida meleagris, respond to an unexpected drop in terrain during running. In particular, we address how joint mechanics are coordinated to achieve whole limb dynamics. Based on muscle–tendon architecture and previous studies of steady and incline locomotion, we hypothesize a proximo-distal gradient in joint neuromechanical control. In this motor control strategy, (1) proximal muscles at the hip and knee joints are controlled primarily in a feedforward manner and exhibit load-insensitive mechanical performance, and (2) distal muscles at the ankle and tarsometatarso-phalangeal (TMP) joints are highly load-sensitive, due to intrinsic mechanical effects and rapid, higher gain proprioceptive feedback. Limb kinematics and kinetics during the unexpected perturbation reveal that limb retraction, controlled largely by the hip, remains similar to level running throughout the perturbed step, despite altered limb loading. Individual joints produce or absorb energy during both level and perturbed running steps, such that the net limb work depends on the balance of energy among the joints. The hip maintains the same mechanical role regardless of limb loading, whereas the ankle and TMP switch between spring-like or damping function depending on limb posture at ground contact. Initial knee angle sets limb posture and alters the balance of work among the joints, although the knee contributes little work itself. This distribution of joint function results in posture-dependent changes in work performance of the limb, which allow guinea fowl to rapidly produce or absorb energy in response to the perturbation. The results support the hypothesis that a proximo-distal gradient exists in limb neuromuscular performance and motor control. This control strategy allows limb cycling to remain constant, whereas limb posture, loading and energy performance are interdependent. We propose that this control strategy provides simple, rapid mechanisms for managing energy and controlling velocity when running over rough terrain. PMID:17234607

Spinal lordosis optimizes the requirements for a stable erect posture.

PubMed

Wagner, Heiko; Liebetrau, Anne; Schinowski, David; Wulf, Thomas; de Lussanet, Marc H E

2012-04-16

Lordosis is the bending of the lumbar spine that gives the vertebral column of humans its characteristic ventrally convex curvature. Infants develop lordosis around the time when they acquire bipedal locomotion. Even macaques develop a lordosis when they are trained to walk bipedally. The aim of this study was to investigate why humans and some animals develop a lumbar lordosis while learning to walk bipedally. We developed a musculoskeletal model of the lumbar spine, that includes an asymmetric, dorsally shifted location of the spinal column in the body, realistic moment arms, and physiological cross-sectional areas (PCSA) of the muscles as well as realistic force-length and force-velocity relationships. The model was used to analyze the stability of an upright body posture. According to our results, lordosis reduces the local joint torques necessary for an equilibrium of the vertebral column during an erect posture. At the same time lordosis increases the demands on the global muscles to provide stability. We conclude that the development of a spinal lordosis is a compromise between the stability requirements of an erect posture and the necessity of torque equilibria at each spinal segment.

Spinal lordosis optimizes the requirements for a stable erect posture

PubMed Central

2012-01-01

Background Lordosis is the bending of the lumbar spine that gives the vertebral column of humans its characteristic ventrally convex curvature. Infants develop lordosis around the time when they acquire bipedal locomotion. Even macaques develop a lordosis when they are trained to walk bipedally. The aim of this study was to investigate why humans and some animals develop a lumbar lordosis while learning to walk bipedally. Results We developed a musculoskeletal model of the lumbar spine, that includes an asymmetric, dorsally shifted location of the spinal column in the body, realistic moment arms, and physiological cross-sectional areas (PCSA) of the muscles as well as realistic force-length and force-velocity relationships. The model was used to analyze the stability of an upright body posture. According to our results, lordosis reduces the local joint torques necessary for an equilibrium of the vertebral column during an erect posture. At the same time lordosis increases the demands on the global muscles to provide stability. Conclusions We conclude that the development of a spinal lordosis is a compromise between the stability requirements of an erect posture and the necessity of torque equilibria at each spinal segment. PMID:22507595

More falls in cerebellar ataxia when standing on a slow up-moving tilt of the support surface

PubMed Central

PAQUETTE, Caroline; FRANZÉN, Erika; HORAK, Fay B

2016-01-01

We investigated how subjects with cerebellar ataxia (CA) adapt their postural stability and alignment to a slow and small tilt of the support surface allowing for online postural corrections. Eight subjects with CA and eight age- and gender-matched healthy control subjects participated in the study. Subjects stood eyes closed for 1 minute after which the support surface was tilted 5° toes-up at a ramp velocity of 1°/s. The toes-up position was held for 2.5 minutes after which the surface rotated back down to level with identical tilt characteristics. As reflected by the large number of falls, subjects with CA had marked difficulty adapting their posture to the up-moving incline in contrast to control subjects. Subjects with CA who lost their balance had faster trunk velocity and excessive backward trunk reorientation beginning within the first second after onset of the tilting surface. In contrast, the down-moving tilt to level did not result in instability in CA subjects. These results suggest that instability and falls associated with CA derives from an inability to maintain trunk orientation to vertical while standing on a slow-moving or unstable surface. This study underscores the importance of the cerebellum in the online sensory control of the upper body orientation during small amplitude and slow velocity movements of the support surface. PMID:26202671

More Falls in Cerebellar Ataxia When Standing on a Slow Up-Moving Tilt of the Support Surface.

PubMed

Paquette, Caroline; Franzén, Erika; Horak, Fay B

2016-06-01

We investigated how subjects with cerebellar ataxia (CA) adapt their postural stability and alignment to a slow and small tilt of the support surface allowing for online postural corrections. Eight subjects with CA and eight age- and gender-matched healthy control subjects participated in the study. Subjects stood eyes closed for 1 min after which the support surface was tilted 5° toes-up at a ramp velocity of 1°/s. The toes-up position was held for 2.5 min after which the surface rotated back down to level with identical tilt characteristics. As reflected by the large number of falls, subjects with CA had marked difficulty adapting their posture to the up-moving incline in contrast to control subjects. Subjects with CA who lost their balance had faster trunk velocity and excessive backward trunk reorientation beginning within the first second after onset of the tilting surface. In contrast, the down-moving tilt to level did not result in instability in CA subjects. These results suggest that instability and falls associated with CA derive from an inability to maintain trunk orientation to vertical while standing on a slow-moving or unstable surface. This study underscores the importance of the cerebellum in the online sensory control of the upper body orientation during small amplitude and slow velocity movements of the support surface.

Light touch leads to increased stability in quiet and perturbed balance: Equivalent effects between post-stroke and healthy older individuals.

PubMed

Martinelli, Alessandra Rezende; Coelho, Daniel Boari; Teixeira, Luis Augusto

2018-04-01

Cerebral damage provoked by stroke may lead to deficits of quiet balance control and of the recovery of body equilibrium following an unanticipated postural perturbation. In this investigation we aimed to evaluate the effect of light touch (LT) of an earth-fixed surface on balance stability in individuals with post-stroke hemiparesis, taking performance of age-matched healthy participants as reference. Evaluations were made in conditions of full and no visual information. Analysis of quiet balance showed that LT induced higher balance stability, with reduced amplitude and velocity of postural sway. Evaluation of the effect of LT on automatic postural responses was made in the task of recovering body equilibrium following a mechanical perturbation of balance leading to fast forward body sway. Results showed that LT led to reduced amplitude of center of mass displacement following the perturbation, in addition to reduced amplitude and velocity of center of pressure under the feet, and lower activation of the lower legs muscles. Those effects of LT were observed in both the post-stroke and control groups, and did not interact with vision availability. Our results indicated then that individuals who suffered a cerebral stroke can stabilize perturbed and non-perturbed postural responses by lightly touching a stable surface to a similar extent of healthy older individuals. Copyright © 2018 Elsevier B.V. All rights reserved.

Seat surface inclination may affect postural stability during Boccia ball throwing in children with cerebral palsy.

PubMed

Tsai, Yung-Shen; Yu, Yi-Chen; Huang, Po-Chang; Cheng, Hsin-Yi Kathy

2014-12-01

The aim of the study was to examine how seat surface inclination affects Boccia ball throwing movement and postural stability among children with cerebral palsy (CP). Twelve children with bilateral spastic CP (3 with gross motor function classification system Level I, 5 with Level II, and 4 with Level III) participated in this study. All participants underwent pediatric reach tests and ball throwing performance analyses while seated on 15° anterior- or posterior-inclined, and horizontal surfaces. An electromagnetic motion analysis system was synchronized with a force plate to assess throwing motion and postural stability. The results of the pediatric reach test (p = 0.026), the amplitude of elbow movement (p = 0.036), peak vertical ground reaction force (PVGRF) (p < 0.001), and movement range of the center of pressure (COP) (p < 0.020) were significantly affected by seat inclination during throwing. Post hoc comparisons showed that anterior inclination allowed greater amplitude of elbow movement and PVGRF, and less COP movement range compared with the other inclines. Posterior inclination yielded less reaching distance and PVGRF, and greater COP movement range compared with the other inclines. The anterior-inclined seat yielded superior postural stability for throwing Boccia balls among children with bilateral spastic CP, whereas the posterior-inclined seat caused difficulty. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dynamic postural stability during advancing pregnancy.

PubMed

McCrory, J L; Chambers, A J; Daftary, A; Redfern, M S

2010-08-26

Pregnant women are at an increased risk of experiencing a fall. Numerous anatomical, physiological, and hormonal alterations occur during pregnancy, but the influence of these factors on dynamic postural stability has not been explored. The purpose of this study was to examine dynamic postural stability in pregnant women during their second and third trimesters as well as in a group of non-pregnant control women. Eighty-one women (41 pregnant, 40 controls) participated stood on a force plate that translated anteroposteriorly at small, medium, and large magnitudes. Reaction time and center of pressure (COP) movement during the translations were analyzed. Trimester, perturbation direction, and perturbation magnitude were the independent variables in a mixed-model analysis of variance on each of the following dependent variables: reaction time, initial sway, total sway, and sway velocity. Reaction time to the perturbation was not significantly different between the groups. Initial sway, total sway, and sway velocity were significantly less during the third trimester than during the second trimester and when compared to the non-pregnant controls (P<0.05). No differences were found in any of the measures between the pregnant women in their second trimesters and the control group. Alterations in sway responses to perturbations are seen in the third trimester in healthy women with uncomplicated pregnancies. Further study is needed to examine the biomechanical and physiological reasons behind this altered dynamic postural stability. 2010 Elsevier Ltd. All rights reserved.

[Development of Patient Transfer Techniques based on Postural-stability Principles for the Care Helpers in Nursing Homes and Evaluation of Effectiveness].

PubMed

Ma, Ryewon; Jung, Dukyoo

2016-02-01

This study was done to develop a postural-stability patient transfer technique for care helpers in nursing homes and to evaluate its effectiveness. Four types of patient transfer techniques (Lifting towards the head board of the bed, turning to the lateral position, sitting upright on the bed, transferring from wheel chair to bed) were practiced in accordance with the following three methods; Care helpers habitually used transfer methods (Method 1), patient transfer methods according to care helper standard textbooks (Method 2), and a method developed by the author ensuring postural-stability (Method 3). The care helpers' muscle activity and four joint angles were measured. The collected data were analyzed using the program SPSS Statistic 21.0. To differentiate the muscle activity and joint angle, the Friedman test was executed and the post-hoc analysis was conducted using the Wilcoxon Signed Rank test. Muscle activity was significantly lower during Method 3 compared to Methods 1 and 2. In addition, the joint angle was significantly lower for the knee and shoulder joint angle while performing Method 3 compared to Methods 1 and 2. Findings indicate that using postural-stability patient transfer techniques can contribute to the prevention of musculoskeletal disease which care helpers suffer from due to physically demanding patient care in nursing homes.

Time-interval for integration of stabilizing haptic and visual information in subjects balancing under static and dynamic conditions

PubMed Central

Honeine, Jean-Louis; Schieppati, Marco

2014-01-01

Maintaining equilibrium is basically a sensorimotor integration task. The central nervous system (CNS) continually and selectively weights and rapidly integrates sensory inputs from multiple sources, and coordinates multiple outputs. The weighting process is based on the availability and accuracy of afferent signals at a given instant, on the time-period required to process each input, and possibly on the plasticity of the relevant pathways. The likelihood that sensory inflow changes while balancing under static or dynamic conditions is high, because subjects can pass from a dark to a well-lit environment or from a tactile-guided stabilization to loss of haptic inflow. This review article presents recent data on the temporal events accompanying sensory transition, on which basic information is fragmentary. The processing time from sensory shift to reaching a new steady state includes the time to (a) subtract or integrate sensory inputs; (b) move from allocentric to egocentric reference or vice versa; and (c) adjust the calibration of motor activity in time and amplitude to the new sensory set. We present examples of processes of integration of posture-stabilizing information, and of the respective sensorimotor time-intervals while allowing or occluding vision or adding or subtracting tactile information. These intervals are short, in the order of 1–2 s for different postural conditions, modalities and deliberate or passive shift. They are just longer for haptic than visual shift, just shorter on withdrawal than on addition of stabilizing input, and on deliberate than unexpected mode. The delays are the shortest (for haptic shift) in blind subjects. Since automatic balance stabilization may be vulnerable to sensory-integration delays and to interference from concurrent cognitive tasks in patients with sensorimotor problems, insight into the processing time for balance control represents a critical step in the design of new balance- and locomotion training devices. PMID:25339872

The effect of a single massage based on the tensegrity principle on postural stability in young women.

PubMed

Cieślik, Błażej; Podsiadły, Ireneusz; Kuczyński, Michał; Ostrowska, Bożena

2017-11-06

The aim of this study was to investigate the effects of normalized muscle tension via tensegrity-based massage on postural stability in a sample of female young adults. Nineteen females aged 21.8 ± 1.9 years were recruited presenting abnormal tension at muscles adhering to any of the following structural sites: superior iliac spine, lateral sacropelvic surface, linea aspera at 1/2 of femur length, and superior nuchal line of the occiput. Balance and postural control were assessed during bipedal stance using a force platform in multiple conditions: hard surface or soft foam surface with the head in either a neutral posture or tilted backward. Baseline and 3-min and 15-min post-treatment measures were collected while barefoot and eyes closed. Main outcomes measures included center of pressure variability, range, radius, and velocity in the anteroposterior (AP) mediolateral (ML) dimensions. In the solid surface with neutral head posture condition only AP COP measures decreased significantly (p< 0.05). In the soft surface condition, significant differences were observed in the AP and ML dimensions among most measures (p< 0.05). A single application of tensegrity-based massage positively influenced postural control in young adult females, particularly in the AP direction.

Effect of higher muscle coactivation on standing postural response to perturbation in older adults.

PubMed

Nagai, Koutatsu; Okita, Yusuke; Ogaya, Shinya; Tsuboyama, Tadao

2017-04-01

Although several studies have reported that muscle coactivation during postural control increases with age, the effect of higher muscle coactivation on standing postural response to perturbation is unknown. To investigate whether higher muscle coactivation affects standing postural response to perturbation in older adults. Thirty-four community-dwelling older participants were randomly assigned either to the coactivation group (CG), where muscle coactivation was increased intentionally, or to the non-coactivation group (NCG). The participants were instructed to stand on a force plate that moved forward or backward. Electromyography data were collected from the lower leg muscles. We requested the participants in the CG to increase the activity of their tibialis anterior, and to maintain this posture during the tasks. We moved the force plate with a constant amplitude and velocity, and measured kinematic data with a camera during the tasks. During forward transfer, the knee extension and hip flexion decreased in the CG after perturbation compared to NCG, and the trunk extension angle increased. The center of pressure (COP) displacement decreased around the peak of the movement in the CG compared to NCG. During backward transfer, ankle dorsal and knee flexion changed after perturbation in the CG compared to NCG. Our study found that higher muscle coactivation inhibits lower limb and COP movement as well as increases trunk tilt and the risk for falls during forward perturbations. Postural control with higher coactivation appears to be inefficient for maintaining balance during the backward sway of posture.

Childhood Exposure to Manganese and Postural Instability in Children living near a Ferromanganese Refinery in Southeastern Ohio

PubMed Central

Rugless, Fedoria; Bhattacharya, Amit; Succop, Paul; Dietrich, Kim N.; Cox, Cyndy; Alden, Jody; Kuhnell, Pierce; Barnas, Mary; Wright, Robert; Parsons, Patrick J.; Praamsma, Meredith L.; Palmer, Christopher D.; Beidler, Caroline; Wittberg, Richard; Haynes, Erin N.

2014-01-01

Airborne manganese (Mn) exposure can result in neurotoxicity and postural instability in occupationally exposed workers, yet few studies have explored the association ambient exposure to Mn in children and postural stability. The goal of this study was to determine the association between Mn and lead (Pb) exposure, as measured by blood Pb, blood and hair Mn and time weighted distance (TWD) from a ferromanganese refinery, and postural stability in children. A subset of children ages 7–9 years enrolled in the Marietta Community Actively Researching Exposure Study (CARES) were invited to participate. Postural balance was conducted on 55 children residing in Marietta, Ohio and the surrounding area. Samples of blood were collected and analyzed for Mn and Pb, and samples of hair were analyzed for Mn. Neuromotor performance was assessed using postural balance testing with a computer force platform system. Pearson correlations were calculated to identify key covariates. Associations between postural balance testing conditions and Mn and Pb exposure were estimated with linear regression analyses adjusting for gender, age, parent IQ, parent age. Mean blood Mn was 10 μg/L (SEM=0.36), mean blood Pb was 0.85 μg/dL (SEM=0.05), and mean hair Mn was 0.76 μg/g (SEM=0.16). Mean residential distance from the refinery was 11.5 km (SEM=0.46). All three measures of Mn exposure were significantly associated with poor postural balance. In addition, low-level blood Pb was also negatively associated with balance outcomes. We conclude that Mn exposure and low-level blood Pb are significantly associated with poor postural balance. PMID:24370548

Anatomy and histochemistry of spread-wing posture in birds. I. Wing drying posture in the double-crested cormorant, Phalacrocorax auritus.

PubMed

Meyers, Ron A

1997-07-01

Spread-wing postures of birds often have been studied with respect to the function of behavior, but ignored with regard to the mechanism by which the birds accomplish posture. The double-crested cormorant, Phalacrocorax auritus, was used as a model for this study of spread-wing posture. Those muscles capable of positioning and maintaining the wing in extension and protraction were assayed histochemically for the presence of slow (postural) muscle fibers. Within the forelimb of Phalacrocorax, Mm. coracobrachialis cranialis, pectoralis thoracicus (cranial portion), deltoideus minor, triceps scapularis, and extensor metacarpi radialis pars dorsalis and ventralis were found to contain populations of slow-twitch or slow-tonic muscle fibers. These slow fibers in the above muscles are considered to function during spread-wing posture in this species. J Morphol 233:67-76, 1997. © 1997 Wiley-Liss, Inc. Copyright © 1997 Wiley-Liss, Inc.

Step-Down Test Assessment of Postural Stability in Patients With Chronic Ankle Instability.

PubMed

Bolt, Doris; Giger, René; Wirth, Stefan; Swanenburg, Jaap

2018-01-23

The underlying mechanism in 27% of ankle sprains is a fall while navigating stairs. Therefore, the step-down test (SDT) may be useful to investigate dynamic postural stability deficits in individuals with chronic ankle instability (CAI). To investigate the test-retest reliability and validity of the forward and lateral SDT protocol between individuals with CAI and uninjured controls. Test-retest study. University hospital. A total of 46  individuals, 23 with CAI and 23 uninjured controls. Time to stabilization of the forward and lateral SDT. The absolute reliability (SEM = 0.04-0.12 s; SDD = 0.11-0.33 s) of the SDT protocol was acceptable, whereas the relative reliability (ICC 3 , k = 0.12-0.63) and discriminant validity (P = .42-.99; AUC = 0.50-0.57) were not. The SDT appears to not be challenging enough to detect dynamic postural stability differences between individuals with and without CAI. However, the SDT may be capable of measuring change over time based on its good absolute reliability.

Effects of weight management program on postural stability and neuromuscular function among obese children: study protocol for a randomized controlled trial.

PubMed

Sun, Fenghua; Wang, Li-Juan; Wang, Lin

2015-04-10

Childhood obesity is one of the most critical public health problems in the world. It is associated with low neuromuscular function and postural deformities. Whether weight loss can improve postural stability and neuromuscular control, benefit daily activities, or prevent injury is unknown. Therefore, this study attempts to investigate the effect of a 6 month weight management program on postural stability and neuromuscular control among obese children. We will conduct a prospective, single-blind, randomized controlled trial with 120 prepubescent obese children. Participants will be randomly assigned to a weight management group or a control group. The weight management group will participate in a dietary and exercise program. The control group will receive health education. After the intervention, participants will be followed for 6 months with no active intervention. The primary and secondary outcomes will be assessed at the baseline, and after 6 months and 12 months. Primary outcome measures will include body weight, body height, body mass index, waist circumference, hip circumference, and body fat percentage. Secondary outcome measures will include three-dimensional functional biomechanics in different tasks, proprioception tests of the knee and ankle, neuromuscular response of the leg muscles, and muscle strength tests of the knee and ankle. Furthermore, adverse events will be recorded and analyzed. An intention-to-treat analysis will be performed if any participants withdraw from the trial. The important features of this trial include the randomization procedures and large sample size. This study attempts to estimate the effect of weight loss intervention on outcomes, including daily life function, postural stability, and neuromuscular control in prepubescent obese children. Therefore, our results can be useful for obese children, medical staff, and healthcare decision makers. Chinese Clinical Trial Registry ChiCTR-IOB-15005874.

Effect of long-duration spaceflight on postural control during self-generated perturbations

NASA Technical Reports Server (NTRS)

Layne, C. S.; Mulavara, A. P.; McDonald, P. V.; Pruett, C. J.; Kozlovskaya, I. B.; Bloomberg, J. J.

2001-01-01

This report is the first systematic evaluation of the effects of prolonged weightlessness on the bipedal postural control processes during self-generated perturbations produced by voluntary upper limb movements. Spaceflight impacts humans in a variety of ways, one of which is compromised postflight postural control. We examined the neuromuscular activation characteristics and center of pressure (COP) motion associated with arm movement of eight subjects who experienced long-duration spaceflight (3--6 mo) aboard the Mir space station. Surface electromyography, arm acceleration, and COP motion were collected while astronauts performed rapid unilateral shoulder flexions before and after spaceflight. Subjects generally displayed compromised postural control after flight, as evidenced by modified COP peak-to-peak anterior-posterior and mediolateral excursion, and pathlength relative to preflight values. These changes were associated with disrupted neuromuscular activation characteristics, particularly after the completion of arm acceleration (i.e., when subjects were attempting to maintain upright posture in response to self-generated perturbations). These findings suggest that, although the subjects were able to assemble coordination modes that enabled them to generate rapid arm movements, the subtle control necessary to maintain bipedal equilibrium evident in their preflight performance is compromised after long-duration spaceflight.

Effect of Long-Duration Spaceflight on Postural Control During Self-Generated Perturbations

NASA Technical Reports Server (NTRS)

Layne, Charles S.; Mulavera, Ajitkumar P.; McDonald, P. Vernon; Pruett, Casey J.; Kozlovskaya, Innessa B.; Bloomberg, Jacob J.

2001-01-01

This report is the first systematic evaluation of the effects of prolonged weightlessness on the bipedal postural control processes during self-generated perturbations produced by voluntary upper limb movements. Spaceflight impacts humans in a variety of ways, one of which is compromised postflight postural control. We examined the neuromuscular activation characteristics and center of pressure motion (COP) associated with arm movement of eight subjects who experienced long duration spaceflight (3-6 months) aboard the Mir space station. Surface electromyography (EMG), arm acceleration, and COP motion were collected while astronauts performed rapid unilateral shoulder flexions prior to and after spaceflight. Subjects displayed compromised postural control after flight as evidenced by modified peak-to-peak COP anterior-posterior and medio-lateral motion and COP pathlength relative to preflight values. These changes were associated with disrupted neuromuscular activation characteristics, particularly after the completion of arm acceleration (i.e. when subjects were attempting to maintain their upright posture). These findings suggest that although the subjects were able to assemble coordination modes that enabled them to generate rapid arm movements, the subtle control necessary to maintain bipedal equilibrium evident in their preflight performance is compromised after long duration spaceflight.

Dynamic stability requirements during gait and standing exergames on the wii fit® system in the elderly

PubMed Central

2012-01-01

Background In rehabilitation, training intensity is usually adapted to optimize the trained system to attain better performance (overload principle). However, in balance rehabilitation, the level of intensity required during training exercises to optimize improvement in balance has rarely been studied, probably due to the difficulty in quantifying the stability level during these exercises. The goal of the present study was to test whether the stabilizing/destabilizing forces model could be used to analyze how stability is challenged during several exergames, that are more and more used in balance rehabilitation, and a dynamic functional task, such as gait. Methods Seven healthy older adults were evaluated with three-dimensional motion analysis during gait at natural and fast speed, and during three balance exergames (50/50 Challenge, Ski Slalom and Soccer). Mean and extreme values for stabilizing force, destabilizing force and the ratio of the two forces (stability index) were computed from kinematic and kinetic data to determine the mean and least level of dynamic, postural and overall balance stability, respectively. Results Mean postural stability was lower (lower mean destabilizing force) during the 50/50 Challenge game than during all the other tasks, but peak postural instability moments were less challenging during this game than during any of the other tasks, as shown by the minimum destabilizing force values. Dynamic stability was progressively more challenged (higher mean and maximum stabilizing force) from the 50/50 Challenge to the Soccer and Slalom games, to the natural gait speed task and to the fast gait speed task, increasing the overall stability difficulty (mean and minimum stability index) in the same manner. Conclusions The stabilizing/destabilizing forces model can be used to rate the level of balance requirements during different tasks such as gait or exergames. The results of our study showed that postural stability did not differ much between the evaluated tasks (except for the 50/50 Challenge), compared to dynamic stability, which was significantly less challenged during the games than during the functional tasks. Games with greater centre of mass displacements and changes in the base of support are likely to stimulate balance control enough to see improvements in balance during dynamic functional tasks, and could be tested in pathological populations with the approach used here. PMID:22607025

Lower Limb Kinematics and Dynamic Postural Stability in Anterior Cruciate Ligament-Reconstructed Female Athletes

PubMed Central

Delahunt, Eamonn; Chawke, Mark; Kelleher, Judy; Murphy, Katie; Prendiville, Anna; Sweeny, Lauren; Patterson, Matt

2013-01-01

Context: Deficits in lower limb kinematics and postural stability are predisposing factors to the development of knee ligamentous injury. The extent to which these deficits are present after anterior cruciate ligament (ACL) reconstruction is still largely unknown. The primary hypothesis of the present study was that female athletes who have undergone ACL reconstruction and who have returned to sport participation would exhibit deficits in dynamic postural stability as well as deficiencies in hip- and knee-joint kinematics when compared with an age-, activity-, and sex-matched uninjured control group. Objective: To investigate dynamic postural stability as quantified by the Star Excursion Balance Test (SEBT) and simultaneous hip- and knee-joint kinematic profiles in female athletes who have undergone ACL reconstruction. Design: Descriptive laboratory study. Setting: University motion-analysis laboratory. Patients or Other Participants: Fourteen female athletes who had previously undergone ACL reconstruction (ACL-R) and 17 age- and sex-matched uninjured controls. Intervention(s): Each participant performed 3 trials of the anterior, posterior-medial, and posterior-lateral directional components of the SEBT. Main Outcome Measure(s): Reach distances for each directional component were quantified and expressed as a percentage of leg length. Simultaneous hip- and knee-joint kinematic profiles were recorded using a motion-analysis system. Results: The ACL-R group had decreased reach distances on the posterior-medial (P < .01) and posterior-lateral (P < .01) directional components of the SEBT. During performance of the directional components of the SEBT, ACL-R participants demonstrated altered hip-joint frontal-, sagittal-, and transverse-plane kinematic profiles (P < .05), as well as altered knee-joint sagittal-plane kinematic profiles (P < .05). Conclusions: Deficits in dynamic postural stability and concomitant altered hip- and knee-joint kinematics are present after ACL reconstruction and return to competitive activity. The extent to which these deficits influence potential future injury is worthy of investigation. PMID:23672381

Correlation between Mechanical Properties of the Ankle Muscles and Postural Sway during the Menstrual Cycle.

PubMed

Yim, JongEun; Petrofsky, Jerrold; Lee, Haneul

2018-03-01

Ankle and foot injuries are common among athletes and physically active individuals. The most common residual disability, ankle sprain, is characterized by instability along with postural sway. If the supporting structures around a joint become lax, posture stability and balance are also affected. Previous studies have examined muscle stiffness and elasticity and postural sway separately; however, the relationship between these factors is yet unknown. It is well known that the levels of sex hormones, especially estrogen, change in women over the phase of the menstrual cycle. Therefore, this study examined the relationship between the mechanical properties of tissue and balance activity using a non-invasive digital palpation device to determine if they undergo any changes over the menstrual cycle in young women. Sixteen young women with regular menstrual cycles completed the study. Tone, stiffness, and elasticity of the ankle muscles (lateral gastrocnemius, peroneus longus, and tibialis anterior) were measured using a non-invasive digital palpation device. Postural sway was recorded while the participants performed balance tasks during ovulation and menstruation. Significantly greater posture sway characteristics and ankle muscle elasticity were found during ovulation than during menstruation; lower tone and stiffness of the ankle muscles were observed at ovulation (p < 0.05). Additionally, weak-to-strong relationships between ankle muscle mechanical properties and postural sway characteristics were found (p < 0.05). These results suggest the effect of estrogen on human connective tissues. We therefore postulate that estrogen increases joint and muscle laxity and affects posture stability according to the phase of the menstrual cycle.

Assisting people with multiple disabilities actively correct abnormal standing posture with a Nintendo Wii balance board through controlling environmental stimulation.

PubMed

Shih, Ching-Hsiang; Shih, Ching-Tien; Chu, Chiung-Ling

2010-01-01

The latest researches adopted software technology turning the Nintendo Wii Balance Board into a high performance change of standing posture (CSP) detector, and assessed whether two persons with multiple disabilities would be able to control environmental stimulation using body swing (changing standing posture). This study extends Wii Balance Board functionality for standing posture correction (i.e., actively adjust abnormal standing posture) to assessed whether two persons with multiple disabilities would be able to actively correct their standing posture by controlling their favorite stimulation on/off using a Wii Balance Board with a newly developed standing posture correcting program (SPCP). The study was performed according to an ABAB design, in which A represented baseline and B represented intervention phases. Data showed that both participants significantly increased time duration of maintaining correct standing posture (TDMCSP) to activate the control system to produce environmental stimulation during the intervention phases. Practical and developmental implications of the findings were discussed.

[Posture and aging. Current fundamental studies and management concepts].

PubMed

Mourey, F; Camus, A; Pfitzenmeyer, P

2000-02-19

FUNDAMENTAL IMPORTANCE OF POSTURE: In the elderly subject, preservation of posture is fundamental to maintaining functional independence. In recent years, there has been much progress in our understanding of the mechanisms underlying strategies used to control equilibrium in the upright position. Physiological aging, associated with diverse disease states, dangerously alters the postural function, particularly anticipated adjustments which allow an adaptation of posture to movement. CLINICAL ASSESSMENT OF POSTURE: Several tests have been developed to assess posture in the elderly subject, particularly the time it takes to start walking. We selected certain tests which can be used in everyday practice to predict falls: the stance test, the improved Romberg test, the "timed get up and go test", measurement of walking cadence, assessment of balance reactions, sitting-standing and standing-sitting movements and capacity to get up off the floor. PATIENT CARE: Elderly patients with equilibrium disorders can benefit from specific personalized rehabilitation protocols. Different techniques have been developed for multiple afferential stimulation, reprogramming postural strategies, and correcting for deficient motor automatisms.

Techniques and Methods for Testing the Postural Function in Healthy and Pathological Subjects

PubMed Central

Paillard, Thierry; Noé, Frédéric

2015-01-01

The different techniques and methods employed as well as the different quantitative and qualitative variables measured in order to objectify postural control are often chosen without taking into account the population studied, the objective of the postural test, and the environmental conditions. For these reasons, the aim of this review was to present and justify the different testing techniques and methods with their different quantitative and qualitative variables to make it possible to precisely evaluate each sensory, central, and motor component of the postural function according to the experiment protocol under consideration. The main practical and technological methods and techniques used in evaluating postural control were explained and justified according to the experimental protocol defined. The main postural conditions (postural stance, visual condition, balance condition, and test duration) were also analyzed. Moreover, the mechanistic exploration of the postural function often requires implementing disturbing postural conditions by using motor disturbance (mechanical disturbance), sensory stimulation (sensory manipulation), and/or cognitive disturbance (cognitive task associated with maintaining postural balance) protocols. Each type of disturbance was tackled in order to facilitate understanding of subtle postural control mechanisms and the means to explore them. PMID:26640800

Techniques and Methods for Testing the Postural Function in Healthy and Pathological Subjects.

PubMed

Paillard, Thierry; Noé, Frédéric

2015-01-01

The different techniques and methods employed as well as the different quantitative and qualitative variables measured in order to objectify postural control are often chosen without taking into account the population studied, the objective of the postural test, and the environmental conditions. For these reasons, the aim of this review was to present and justify the different testing techniques and methods with their different quantitative and qualitative variables to make it possible to precisely evaluate each sensory, central, and motor component of the postural function according to the experiment protocol under consideration. The main practical and technological methods and techniques used in evaluating postural control were explained and justified according to the experimental protocol defined. The main postural conditions (postural stance, visual condition, balance condition, and test duration) were also analyzed. Moreover, the mechanistic exploration of the postural function often requires implementing disturbing postural conditions by using motor disturbance (mechanical disturbance), sensory stimulation (sensory manipulation), and/or cognitive disturbance (cognitive task associated with maintaining postural balance) protocols. Each type of disturbance was tackled in order to facilitate understanding of subtle postural control mechanisms and the means to explore them.

Balance rehabilitation: promoting the role of virtual reality in patients with diabetic peripheral neuropathy.

PubMed

Grewal, Gurtej S; Sayeed, Rashad; Schwenk, Michael; Bharara, Manish; Menzies, Robert; Talal, Talal K; Armstrong, David G; Najafi, Bijan

2013-01-01

Individuals with diabetic peripheral neuropathy frequently experience concomitant impaired proprioception and postural instability. Conventional exercise training has been demonstrated to be effective in improving balance but does not incorporate visual feedback targeting joint perception, which is an integral mechanism that helps compensate for impaired proprioception in diabetic peripheral neuropathy. This prospective cohort study recruited 29 participants (mean ± SD: age, 57 ± 10 years; body mass index [calculated as weight in kilograms divided by height in meters squared], 26.9 ± 3.1). Participants satisfying the inclusion criteria performed predefined ankle exercises through reaching tasks, with visual feedback from the ankle joint projected on a screen. Ankle motion in the mediolateral and anteroposterior directions was captured using wearable sensors attached to the participant's shank. Improvements in postural stability were quantified by measuring center of mass sway area and the reciprocal compensatory index before and after training using validated body-worn sensor technology. Findings revealed a significant reduction in center of mass sway after training (mean, 22%; P = .02). A higher postural stability deficit (high body sway) at baseline was associated with higher training gains in postural balance (reduction in center of mass sway) (r = -0.52, P < .05). In addition, significant improvement was observed in postural coordination between the ankle and hip joints (mean, 10.4%; P = .04). The present research implemented a novel balance rehabilitation strategy based on virtual reality technology. The method included wearable sensors and an interactive user interface for real-time visual feedback based on ankle joint motion, similar to a video gaming environment, for compensating impaired joint proprioception. These findings support that visual feedback generated from the ankle joint coupled with motor learning may be effective in improving postural stability in patients with diabetic peripheral neuropathy.

Measuring Postural Stability: Strategies For Signal Acquisition And Processing

NASA Astrophysics Data System (ADS)

Riedel, Susan A.; Harris, Gerald F.

1987-01-01

A balance platform was used to collect postural stability data from 60 children, approximately half of whom have been diagnosed with cerebral palsy. The data was examined with respect to its frequency content, resulting in an improved strategy for frequency estimation. With a reliable assessment of the frequency domain characteristics, the signal stationarity could then be examined. Significant differences in signal stationarity were observed when the epoch length was changed, as well as between the normal and cerebral palsy populations.

Benefit of bi-ocular visual stimulation for postural control in children with strabismus.

PubMed

Gaertner, Chrystal; Creux, Charlotte; Espinasse-Berrod, Marie-Andrée; Orssaud, Christophe; Dufier, Jean-Louis; Kapoula, Zoï

2013-01-01

Vision is important for postural control as is shown by the Romberg quotient (RQ): with eyes closed, postural instability increases relative to eyes open (RQ = 2). Yet while fixating at far distance, postural stability is similar with eyes open and eyes closed (RQ = 1). Postural stability can be better with both eyes viewing than one eye, but such effect is not consistent among healthy subjects. The first goal of the study is to test the RQ as a function of distance for children with convergent versus divergent strabismus. The second goal is to test whether vision from two eyes relative to vision from one eye provides better postural stability. Thirteen children with divergent strabismus and eleven with convergent strabismus participated in this study. Posturtography was done with the Techno concept device. Experiment 1, four conditions: fixation at 40 cm and at 200 cm both with eyes open and eyes covered (evaluation of RQ). Experiment 2, six conditions: fixation at 40 cm and at 200 cm, with both eyes viewing or under monocular vision (dominant and non-dominant eye). For convergent strabismus, the groups mean value of RQ was 1.3 at near and 0.94 at far distance; for divergent, it was 1.06 at near and 1.68 at far. For all children, the surface of body sway was significantly smaller under both eyes viewing than monocular viewing (either eye). Increased RQ value at near for convergent and at far for divergent strabismus is attributed to the influence of the default strabismus angle and to better use of ocular motor signals. Vision with the two eyes improves postural control for both viewing distances and for both types of strabismus. Such benefit can be due to complementary mechanisms: larger visual field, better quality of fixation and vergence angle due to the use of visual inputs from both eyes.

Tail function during arboreal quadrupedalism in squirrel monkeys (Saimiri boliviensis) and tamarins (Saguinus oedipus).

PubMed

Young, Jesse W; Russo, Gabrielle A; Fellmann, Connie D; Thatikunta, Meena A; Chadwell, Brad A

2015-10-01

The need to maintain stability on narrow branches is often presented as a major selective force shaping primate morphology, with adaptations to facilitate grasping receiving particular attention. The functional importance of a long and mobile tail for maintaining arboreal stability has been comparatively understudied. Tails can facilitate arboreal balance by acting as either static counterbalances or dynamic inertial appendages able to modulate whole-body angular momentum. We investigate associations between tail use and inferred grasping ability in two closely related cebid platyrrhines-cotton-top tamarins (Saguinus oedipus) and black-capped squirrel monkeys (Saimiri boliviensis). Using high-speed videography of captive monkeys moving on 3.2 cm diameter poles, we specifically test the hypothesis that squirrel monkeys (characterized by grasping extremities with long digits) will be less dependent on the tail for balance than tamarins (characterized by claw-like nails, short digits, and a reduced hallux). Tamarins have relatively longer tails than squirrel monkeys, move their tails through greater angular amplitudes, at higher angular velocities, and with greater angular accelerations, suggesting dynamic use of tail to regulate whole-body angular momentum. By contrast, squirrel monkeys generally hold their tails in a comparatively stationary posture and at more depressed angles, suggesting a static counterbalancing mechanism. This study, the first empirical test of functional tradeoffs between grasping ability and tail use in arboreal primates, suggests a critical role for the tail in maintaining stability during arboreal quadrupedalism. Our findings have the potential to inform our functional understanding of tail loss during primate evolution. © 2015 Wiley Periodicals, Inc.

Losing touch: age-related changes in plantar skin sensitivity, lower limb cutaneous reflex strength, and postural stability in older adults

PubMed Central

Peters, Ryan M.; McKeown, Monica D.; Carpenter, Mark G.

2016-01-01

Age-related changes in the density, morphology, and physiology of plantar cutaneous receptors negatively impact the quality and quantity of balance-relevant information arising from the foot soles. Plantar perceptual sensitivity declines with age and may predict postural instability; however, alteration in lower limb cutaneous reflex strength may also explain greater instability in older adults and has yet to be investigated. We replicated the age-related decline in sensitivity by assessing monofilament and vibrotactile (30 and 250 Hz) detection thresholds near the first metatarsal head bilaterally in healthy young and older adults. We additionally applied continuous 30- and 250-Hz vibration to drive mechanically evoked reflex responses in the tibialis anterior muscle, measured via surface electromyography. To investigate potential relationships between plantar sensitivity, cutaneous reflex strength, and postural stability, we performed posturography in subjects during quiet standing without vision. Anteroposterior and mediolateral postural stability decreased with age, and increases in postural sway amplitude and frequency were significantly correlated with increases in plantar detection thresholds. With 30-Hz vibration, cutaneous reflexes were observed in 95% of young adults but in only 53% of older adults, and reflex gain, coherence, and cumulant density at 30 Hz were lower in older adults. Reflexes were not observed with 250-Hz vibration, suggesting this high-frequency cutaneous input is filtered out by motoneurons innervating tibialis anterior. Our findings have important implications for assessing the risk of balance impairment in older adults. PMID:27489366

Examining the effects of postural constraints on estimating reach.

PubMed

Gabbard, Carl; Cordova, Alberto; Lee, Sunghan

2007-07-01

The tendency to overestimate has consistently been reported in studies of reachability estimation. According to one of the more prominent explanations, the postural stability hypothesis, the perceived reaching limit depends on the individual's perceived postural constraints. To test that proposition, the authors compared estimates of reachability of 38 adults (a) in the seated posture (P1) and (b) in the more demanding posture of standing on one foot and leaning forward (P2). Although there was no difference between conditions for total error, results for the distribution and direction of error indicated that participants overestimated in the P1 condition and underestimated in the P2 condition. It therefore appears that perceived postural constraints could be a factor in judgments of reachability. When participants in the present study perceived greater postural demands, they may have elected to program a more conservative strategy that resulted in underestimation.

Anticipatory control of impending postural perturbation in elite springboard divers.

PubMed

Popa, T; Bonifazi, M; della Volpe, R; Rossi, A; Mazzocchio, R

2008-12-01

Among athletes, elite springboard divers (ED) should develop an optimal anticipatory control of postural stability, as a result of specific training. Postural strategies of ED and healthy subjects (HS) while expecting an impending perturbation were compared. The mean center of pressure (COP) position was analyzed during control quiet stance (cQS) and during anticipatory quiet stance (aQS(1-4)), i.e., in expectation of four backward translations of the support surface. During cQS, COP position in ED was not significantly different as compared to HS. During aQS(1-4,) a significant increase in the mean COP position was observed in both groups with ED adopting a more forward inclined vertical alignment than HS. In ED specific training may have resulted in a reference frame offset in a more anterior direction while expecting an impending perturbation. We suggest that leaning more forward may represent a more reliable way of coping with predictable perturbations of postural stability.

Analysis of Human Body Bipedal Stability for Neuromotor Disabilities

NASA Astrophysics Data System (ADS)

Baritz, Mihaela; Cristea, Luciana; Rogozea, Liliana; Cotoros, Diana; Repanovici, Angela

2009-04-01

The analysis of different biomechanical aspects of balance and equilibrium is presented in the first part of the paper. We analyzed the posture, balance and stability of human body for a normal person and for a person with loco-motor or neuro-motor disabilities (in the second part). In the third part of the paper we presented the methodology and the experimental setup used to record the human body behavior in postural stability for persons with neuro-motors disabilities. The results and the conclusions are presented in the final part of the paper and also in the future work meant to establish the computer analysis for rehabilitation neuromotor disabilities.

Postural Control Impairments in Individuals With Autism Spectrum Disorder: A Critical Review of Current Literature

PubMed Central

Memari, Amir Hossein; Ghanouni, Parisa; Shayestehfar, Monir; Ghaheri, Banafsheh

2014-01-01

Context: Motor impairments in individuals with autism spectrum disorder (ASD) have been frequently reported. In this review, we narrow our focus on postural control impairments to summarize current literature for patterns, underlying mechanisms, and determinants of posture in this population. Evidence Acquisition: A literature search was conducted through Medline, ISI web of Knowledge, Scopus and Google Scholar to include studies between 1992 and February 2013. Results: Individuals with ASD have problems in maintaining postural control in infancy that well persists into later years. However, the patterns and underlying mechanisms are still unclear. Conclusions: Examining postural control as an endophenotype or early diagnostic marker of autism is a conceptual premise which should be considered in future investigations. At the end of the review, methodological recommendations on the assessment of postural control have also been provided. PMID:25520765

Evaluation of Postural Control in Patients with Glaucoma Using a Virtual Reality Environment.

PubMed

Diniz-Filho, Alberto; Boer, Erwin R; Gracitelli, Carolina P B; Abe, Ricardo Y; van Driel, Nienke; Yang, Zhiyong; Medeiros, Felipe A

2015-06-01

To evaluate postural control using a dynamic virtual reality environment and the relationship between postural metrics and history of falls in patients with glaucoma. Cross-sectional study. The study involved 42 patients with glaucoma with repeatable visual field defects on standard automated perimetry (SAP) and 38 control healthy subjects. Patients underwent evaluation of postural stability by a force platform during presentation of static and dynamic visual stimuli on stereoscopic head-mounted goggles. The dynamic visual stimuli presented rotational and translational ecologically valid peripheral background perturbations. Postural stability was also tested in a completely dark field to assess somatosensory and vestibular contributions to postural control. History of falls was evaluated by a standard questionnaire. Torque moments around the center of foot pressure on the force platform were measured, and the standard deviations of the torque moments (STD) were calculated as a measurement of postural stability and reported in Newton meters (Nm). The association with history of falls was investigated using Poisson regression models. Age, gender, body mass index, severity of visual field defect, best-corrected visual acuity, and STD on dark field condition were included as confounding factors. Patients with glaucoma had larger overall STD than controls during both translational (5.12 ± 2.39 Nm vs. 3.85 ± 1.82 Nm, respectively; P = 0.005) and rotational stimuli (5.60 ± 3.82 Nm vs. 3.93 ± 2.07 Nm, respectively; P = 0.022). Postural metrics obtained during dynamic visual stimuli performed better in explaining history of falls compared with those obtained in static and dark field condition. In the multivariable model, STD values in the mediolateral direction during translational stimulus were significantly associated with a history of falls in patients with glaucoma (incidence rate ratio, 1.85; 95% confidence interval, 1.30-2.63; P = 0.001). The study presented and validated a novel paradigm for evaluation of balance control in patients with glaucoma on the basis of the assessment of postural reactivity to dynamic visual stimuli using a virtual reality environment. The newly developed metrics were associated with a history of falls and may help to provide a better understanding of balance control in patients with glaucoma. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Evaluation of Postural Control in Glaucoma Patients Using a Virtual 1 Reality Environment

PubMed Central

Diniz-Filho, Alberto; Boer, Erwin R.; Gracitelli, Carolina P. B.; Abe, Ricardo Y.; van Driel, Nienke; Yang, Zhiyong; Medeiros, Felipe A.

2015-01-01

Purpose To evaluate postural control using a dynamic virtual reality environment and the relationship between postural metrics and history of falls in glaucoma patients. Design Cross-sectional study. Participants The study involved 42 glaucoma patients with repeatable visual field defects on standard automated perimetry (SAP) and 38 control healthy subjects. Methods Patients underwent evaluation of postural stability by a force platform during presentation of static and dynamic visual stimuli on stereoscopic head-mounted goggles. The dynamic visual stimuli presented rotational and translational ecologically valid peripheral background perturbations. Postural stability was also tested in a completely dark field to assess somatosensory and vestibular contributions to postural control. History of falls was evaluated by a standard questionnaire. Main Outcome Measures Torque moments around the center of foot pressure on the force platform were measured and the standard deviations (STD) of these torque moments were calculated as a measurement of postural stability and reported in Newton meter (Nm). The association with history of falls was investigated using Poisson regression models. Age, gender, body mass index, severity of visual field defect, best-corrected visual acuity, and STD on dark field condition were included as confounding factors. Results Glaucoma patients had larger overall STD than controls during both translational (5.12 ± 2.39 Nm vs. 3.85 ± 1.82 Nm, respectively; P = 0.005) as well as rotational stimuli (5.60 ± 3.82 Nm vs. 3.93 ± 2.07 Nm, respectively; P = 0.022). Postural metrics obtained during dynamic visual stimuli performed better in explaining history of falls compared to those obtained in static and dark field condition. In the multivariable model, STD values in the mediolateral direction during translational stimulus were significantly associated with history of falls in glaucoma patients (incidence-rate ratio = 1.85; 95% CI: 1.30 – 2.63; P = 0.001). Conclusions The study presented and validated a novel paradigm for evaluation of balance control in glaucoma patients based on the assessment of postural reactivity to dynamic visual stimuli using a virtual reality environment. The newly developed metrics were associated with history of falls and may help to provide a better understanding of balance control in glaucoma patients. PMID:25892017

Effect of Posture on Hip Angles and Moments during Gait

PubMed Central

Lewis, Cara L.; Sahrmann, Shirley A.

2014-01-01

Anterior hip pain is common in young, active adults. Clinically, we have noted that patients with anterior hip pain often walk in a swayback posture, and that their pain is reduced when the posture is corrected. The purpose of this study was to investigate a potential mechanism for the reduction in pain by testing the effect of posture on movement patterns and internal moments during gait in healthy subjects. Fifteen subjects were instructed to walk while maintaining three postures: 1) natural, 2) swayback, and 3) forward flexed. Kinematic and force data were collected using a motion capture system and a force plate. Walking in the swayback posture resulted in a higher peak hip extension angle, hip flexor moment and hip flexion angular impulse compared to natural posture. In contrast, walking in a forward flexed posture resulted in a decreased hip extension angle and decreased hip flexion angular impulse. Based on these results, walking in a swayback posture may result in increased forces required of the anterior hip structures, potentially contributing to anterior hip pain. This study provides a potential biomechanical mechanism for clinical observations that posture correction in patients with hip pain is beneficial. PMID:25262565

Effect of posture on hip angles and moments during gait.

PubMed

Lewis, Cara L; Sahrmann, Shirley A

2015-02-01

Anterior hip pain is common in young, active adults. Clinically, we have noted that patients with anterior hip pain often walk in a swayback posture, and that their pain is reduced when the posture is corrected. The purpose of this study was to investigate a potential mechanism for the reduction in pain by testing the effect of posture on movement patterns and internal moments during gait in healthy subjects. Fifteen subjects were instructed to walk while maintaining three postures: 1) natural, 2) swayback, and 3) forward flexed. Kinematic and force data were collected using a motion capture system and a force plate. Walking in the swayback posture resulted in a higher peak hip extension angle, hip flexor moment and hip flexion angular impulse compared to natural posture. In contrast, walking in a forward flexed posture resulted in a decreased hip extension angle and decreased hip flexion angular impulse. Based on these results, walking in a swayback posture may result in increased forces required of the anterior hip structures, potentially contributing to anterior hip pain. This study provides a potential biomechanical mechanism for clinical observations that posture correction in patients with hip pain is beneficial. Copyright © 2014 Elsevier Ltd. All rights reserved.

Changes in sitting posture induce multiplanar changes in chest wall shape and motion with breathing.

PubMed

Lee, Linda-Joy; Chang, Angela T; Coppieters, Michel W; Hodges, Paul W

2010-03-31

This study examined the effect of sitting posture on regional chest wall shape in three dimensions, chest wall motion (measured with electromagnetic motion analysis system), and relative contributions of the ribcage and abdomen to tidal volume (%RC/V(t)) (measured with inductance plethysmography) in 7 healthy volunteers. In seven seated postures, increased dead space breathing automatically increased V(t) (to 1.5 V(t)) to match volume between conditions and study the effects of posture independent of volume changes. %RC/V(t) (p<0.05), chest wall shape (p<0.05) and motion during breathing differed between postures. Compared to a reference posture, movement at the 9th rib lateral diameter increased in the thoracolumbar extension posture (p<0.008). In slumped posture movement at the AP diameters at T1 and axilla increased (p<0.00001). Rotation postures decreased movement in the lateral diameter at the axilla (p<0.0007). The data show that single plane changes in sitting posture alter three-dimensional ribcage configuration and chest wall kinematics during breathing, while maintaining constant respiratory function. Copyright 2010 Elsevier B.V. All rights reserved.

Improvement of posture stability by vibratory stimulation following anterior cruciate ligament reconstruction.

PubMed

Brunetti, O; Filippi, G M; Lorenzini, M; Liti, A; Panichi, R; Roscini, M; Pettorossi, V E; Cerulli, G

2006-11-01

Surgical reconstruction of the anterior cruciate ligament (ACL) may reduce, but it does not always eliminate, knee and body instability because of a persisting proprioceptive deficit. In order to enhance body stability, a new protocol of treatment has been proposed consisting of mechanical vibration (100 Hz frequency and < 20 microm amplitude) of the quadriceps muscle in the leg that has undergone ACL reconstruction. In our trials, stimulation was performed when the quadriceps muscle was kept isometrically contracted. Treatment was started one month after surgery. Vibration was applied for short periods over three consecutive days. Nine months after treatment, postural stability was re-evaluated with the subjects standing on one leg with open and with closed eyes. The postural stability of the subjects having undergone vibration treatment, standing on the operated leg was significantly improved one day after treatment when evaluated as mean of speed and elliptic area of the center of pressure. The improvement persisted and increased during the following weeks. Peak torques of the operated leg extensor muscles also increased and reached values close to that of the leg, which had not been operated. Conversely, the balance of the untreated subjects standing on the operated leg did not improve and the restoration of the extensor muscle peak torque was poor. It is concluded that short lasting proprioceptive activation by vibration may lead to a faster and more complete equilibrium recovery probably by permanently changing the network controlling knee posture.

The Effect of Spinal Tap Test on Different Sensory Modalities of Postural Stability in Idiopathic Normal Pressure Hydrocephalus.

PubMed

Abram, Katrin; Bohne, Silvia; Bublak, Peter; Karvouniari, Panagiota; Klingner, Carsten M; Witte, Otto W; Guntinas-Lichius, Orlando; Axer, Hubertus

2016-01-01

Postural instability in patients with normal pressure hydrocephalus (NPH) is a most crucial symptom leading to falls with secondary complications. The aim of the current study was to evaluate the therapeutic effect of spinal tap on postural stability in these patients. Seventeen patients with clinical symptoms of NPH were examined using gait scale, computerized dynamic posturography (CDP), and neuropsychological assessment. Examinations were done before and after spinal tap test. The gait score showed a significant improvement 24 h after spinal tap test in all subtests and in the sum score (p < 0.003), while neuropsychological assessment did not reveal significant differences 72 h after spinal tap test. CDP showed significant improvements after spinal tap test in the Sensory Organization Tests 2 (p = 0.017), 4 (p = 0.001), and 5 (p = 0.009) and the composite score (p = 0.01). Patients showed best performance in somatosensory and worst performance in vestibular dominated tests. Vestibular dominated tests did not improve significantly after spinal tap test, while somatosensory and visual dominated tests did. Postural stability in NPH is predominantly affected by deficient vestibular functions, which did not improve after spinal tap test. Conditions which improved best were mainly independent from visual control and are based on proprioceptive functions.

Effects of circumferential ankle pressure on ankle proprioception, stiffness, and postural stability: a preliminary investigation.

PubMed

You, Sung H; Granata, Kevin P; Bunker, Linda K

2004-08-01

Cross-sectional repeated-measures design. Determine the effects of circumferential ankle pressure (CAP) intervention on proprioceptive acuity, ankle stiffness, and postural stability. The application of CAP using braces, taping, and adaptive shoes or military boots is widely used to address chronic ankle instability (CAI). An underlying assumption is that the CAP intervention might improve ankle stability through increased proprioceptive acuity and stiffness in the ankle. METHOD AND MEASURES: A convenience sample of 10 subjects was recruited from the local university community and categorized according to proprioceptive acuity (high, low) and ankle stability (normal, CAI). Proprioceptive acuity was measured when blindfolded subjects were asked to accurately reproduce a self-selected target ankle position before and after the application of CAP. Proprioceptive acuity was determined in 5 different ankle joint position sense tests: neutral, inversion, eversion, plantar flexion, and dorsiflexion. Joint position angles were recorded electromechanically using a potentiometer. Passive ankle stiffness was computed from the ratio of applied static moment versus angular displacement. Active ankle stiffness was determined from biomechanical analyses of ankle motion following a mediolateral perturbation. Postural stability was quantified from the center of pressure displacement in the mediolateral and the anteroposterior directions in unipedal stance. All measurements were recorded with and without CAP applied by a pediatric blood pressure cuff. Data were analyzed using a separate mixed-model analysis of variance (ANOVA) for each dependent variable. Post hoc comparison using Tukey's honestly significant difference (HSD) test was performed if significant interactions were obtained. Significance level was set at P<.05 for all analyses. Significant group (high versus low proprioceptive acuity) x CAP interactions were identified for postural stability. Passive ankle stiffness was not increased by an application of CAP. Active ankle stiffness was significantly different between the high and low proprioceptive acuity groups and was not affected by an application of CAP. Significant group (normal versus CAI) x CAP interactions were observed for mediolateral center-of-pressure displacement with a main effect of group on neutral joint position sense. Application of CAP increased proprioceptive acuity and demonstrated trends toward increased active stiffness in the ankle, hence improved postural stability. The effects tend to be limited to individuals with low proprioceptive acuity.

Effect of 6 days of support withdrawal on characteristics of balance function

NASA Astrophysics Data System (ADS)

Sayenko, D.; Artamonov, A. A.; Ivanov, O. G.; Kozlovskaya, I. B.

2005-08-01

The role of different sensorimotor and sensory factors on postural disorders at different stages of the exposure to microgravity still remains unknown. The results obtained after the Dry Immersion (DI) exposure, showed that after 6 days of DI the subjects' ability to resist to posture perturbations was highly reduced, the EMG response of corrective muscles was increased, and the structure of corrective responses was modified, so that the equilibrium was maintained by the elimination of excessive degrees of freedom. Thus, the results of the study have revealed profound changes in postural synergies suggesting a significant contribution of the support afferentation to posture control.

The internal representation of head orientation differs for conscious perception and balance control

PubMed Central

Dalton, Brian H.; Rasman, Brandon G.; Inglis, J. Timothy

2017-01-01

Key points We tested perceived head‐on‐feet orientation and the direction of vestibular‐evoked balance responses in passively and actively held head‐turned postures.The direction of vestibular‐evoked balance responses was not aligned with perceived head‐on‐feet orientation while maintaining prolonged passively held head‐turned postures. Furthermore, static visual cues of head‐on‐feet orientation did not update the estimate of head posture for the balance controller.A prolonged actively held head‐turned posture did not elicit a rotation in the direction of the vestibular‐evoked balance response despite a significant rotation in perceived angular head posture.It is proposed that conscious perception of head posture and the transformation of vestibular signals for standing balance relying on this head posture are not dependent on the same internal representation. Rather, the balance system may operate under its own sensorimotor principles, which are partly independent from perception. Abstract Vestibular signals used for balance control must be integrated with other sensorimotor cues to allow transformation of descending signals according to an internal representation of body configuration. We explored two alternative models of sensorimotor integration that propose (1) a single internal representation of head‐on‐feet orientation is responsible for perceived postural orientation and standing balance or (2) conscious perception and balance control are driven by separate internal representations. During three experiments, participants stood quietly while passively or actively maintaining a prolonged head‐turned posture (>10 min). Throughout the trials, participants intermittently reported their perceived head angular position, and subsequently electrical vestibular stimuli were delivered to elicit whole‐body balance responses. Visual recalibration of head‐on‐feet posture was used to determine whether static visual cues are used to update the internal representation of body configuration for perceived orientation and standing balance. All three experiments involved situations in which the vestibular‐evoked balance response was not orthogonal to perceived head‐on‐feet orientation, regardless of the visual information provided. For prolonged head‐turned postures, balance responses consistent with actual head‐on‐feet posture occurred only during the active condition. Our results indicate that conscious perception of head‐on‐feet posture and vestibular control of balance do not rely on the same internal representation, but instead treat sensorimotor cues in parallel and may arrive at different conclusions regarding head‐on‐feet posture. The balance system appears to bypass static visual cues of postural orientation and mainly use other sensorimotor signals of head‐on‐feet position to transform vestibular signals of head motion, a mechanism appropriate for most daily activities. PMID:28035656

The effects of arm crank ergometry, cycle ergometry and treadmill walking on postural sway in healthy older females.

PubMed

Hill, M W; Oxford, S W; Duncan, M J; Price, M J

2015-01-01

Older adults are increasingly being encouraged to exercise but this may lead to muscle fatigue, which can adversely affect postural stability. Few studies have investigated the effects of upper body exercise on postural sway in groups at risk of falling, such as the elderly. The purpose of this study was to compare the effects arm crank ergometry (ACE), cycle ergometry (CE) and treadmill walking (TM) on postural sway in healthy older females. In addition, this study sought to determine the time necessary to recover postural control after exercise. A total of nine healthy older females participated in this study. Participants stood on a force platform to assess postural sway which was measured by displacement of the centre of pressure before and after six separate exercise trials. Each participant completed three incremental exercise tests to 85% of individual's theoretical maximal heart rate (HRMAX) for ACE, CE and TM. Subsequent tests involved 20-min of ACE, CE and TM exercise at a relative workload corresponding to 50% of each individual's predetermined heart rate reserve (HRE). Post fatigue effects and postural control recovery were measured at different times after exercise (1, 3, 5, 10, 15 and 30-min). None of the participants exhibited impaired postural stability after ACE. In contrast, CE and TM elicited significant post exercise balance impairments, which lasted for ∼ 10 min post exercise. We provide evidence of an exercise mode which does not elicit post exercise balance impairments. Older adults should exercise caution immediately following exercise engaging the lower limbs to avoid fall risk. Copyright © 2014 Elsevier B.V. All rights reserved.

Short-term effects of 890-nanometer radiation on pain, physical activity, and postural stability in patients with knee osteoarthritis: a double-blind, randomized, placebo-controlled study.

PubMed

Hsieh, Ru-Lan; Lo, Min-Tzu; Liao, Wei-Cheng; Lee, Wen-Chung

2012-05-01

To investigate the effects of short-term light therapy with 890-nm radiation on pain, physical activity, and postural stability in patients with knee osteoarthritis (OA). A double-blind, randomized, placebo-controlled study. Rehabilitation clinic. Women (n=62) and men (n=10) with a mean age of 61.2 years (range, 40-88y). All patients fulfilled the combined clinical and radiographic criteria for knee OA as established by the American College of Rheumatology, and all had obtained a Kellgren-Lawrence score of 2 or more. Participants received 6 sessions, lasting 40 minutes each, of active or placebo radiation treatment over the knee joints for 2 weeks (wavelength, 890nm; radiant power output, 6.24W; power density, 34.7mW/cm(2) for 40 minutes; total energy, 41.6J/cm(2) per knee per session). Participants were assessed weekly over 4 weeks using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for pain, stiffness, and physical function. Physical activity (timed stair climbing, 10-m fast-speed walking, and chair-rising time) and postural stability (using the postural stability evaluation system) were also assessed. The pain score on WOMAC was the primary outcome variable. Data were analyzed by repeated-measures analysis of covariance. Compared with baseline, no significant improvement was observed between groups for pain (P=.546), stiffness (P=.573), or physical function (P=.904). No significant improvement was noted for physical activity including the 10-m fast-speed walking time (P=.284), stair-climbing time (P=.202), stair-descending time (P=.468), chair-rising time (P=.499), or postural stability (P=.986) at the 4 follow-up assessments. Follow-up assessments were conducted after 1 week of treatment (thus, after 3 treatments); after 2 weeks of treatment (thus, after 6 treatments); and 1 and 2 weeks, respectively, after treatment was terminated. Although we found a significant time effect for the 10-m fast-speed walking time (P<.001) in the 2 groups, and a significant group effect in the improvement of stair-climbing time in the treatment group (P=.032), the group × time interaction effects were not significant. Short-term 890-nm radiation therapy for patients with knee OA provided no beneficial effect in improving pain, physical activity, and postural stability. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Brain-state classification and a dual-state decoder dramatically improve the control of cursor movement through a brain-machine interface

NASA Astrophysics Data System (ADS)

Sachs, Nicholas A.; Ruiz-Torres, Ricardo; Perreault, Eric J.; Miller, Lee E.

2016-02-01

Objective. It is quite remarkable that brain machine interfaces (BMIs) can be used to control complex movements with fewer than 100 neurons. Success may be due in part to the limited range of dynamical conditions under which most BMIs are tested. Achieving high-quality control that spans these conditions with a single linear mapping will be more challenging. Even for simple reaching movements, existing BMIs must reduce the stochastic noise of neurons by averaging the control signals over time, instead of over the many neurons that normally control movement. This forces a compromise between a decoder with dynamics allowing rapid movement and one that allows postures to be maintained with little jitter. Our current work presents a method for addressing this compromise, which may also generalize to more highly varied dynamical situations, including movements with more greatly varying speed. Approach. We have developed a system that uses two independent Wiener filters as individual components in a single decoder, one optimized for movement, and the other for postural control. We computed an LDA classifier using the same neural inputs. The decoder combined the outputs of the two filters in proportion to the likelihood assigned by the classifier to each state. Main results. We have performed online experiments with two monkeys using this neural-classifier, dual-state decoder, comparing it to a standard, single-state decoder as well as to a dual-state decoder that switched states automatically based on the cursor’s proximity to a target. The performance of both monkeys using the classifier decoder was markedly better than that of the single-state decoder and comparable to the proximity decoder. Significance. We have demonstrated a novel strategy for dealing with the need to make rapid movements while also maintaining precise cursor control when approaching and stabilizing within targets. Further gains can undoubtedly be realized by optimizing the performance of the individual movement and posture decoders.

Brain-state classification and a dual-state decoder dramatically improve the control of cursor movement through a brain-machine interface.

PubMed

Sachs, Nicholas A; Ruiz-Torres, Ricardo; Perreault, Eric J; Miller, Lee E

2016-02-01

It is quite remarkable that brain machine interfaces (BMIs) can be used to control complex movements with fewer than 100 neurons. Success may be due in part to the limited range of dynamical conditions under which most BMIs are tested. Achieving high-quality control that spans these conditions with a single linear mapping will be more challenging. Even for simple reaching movements, existing BMIs must reduce the stochastic noise of neurons by averaging the control signals over time, instead of over the many neurons that normally control movement. This forces a compromise between a decoder with dynamics allowing rapid movement and one that allows postures to be maintained with little jitter. Our current work presents a method for addressing this compromise, which may also generalize to more highly varied dynamical situations, including movements with more greatly varying speed. We have developed a system that uses two independent Wiener filters as individual components in a single decoder, one optimized for movement, and the other for postural control. We computed an LDA classifier using the same neural inputs. The decoder combined the outputs of the two filters in proportion to the likelihood assigned by the classifier to each state. We have performed online experiments with two monkeys using this neural-classifier, dual-state decoder, comparing it to a standard, single-state decoder as well as to a dual-state decoder that switched states automatically based on the cursor's proximity to a target. The performance of both monkeys using the classifier decoder was markedly better than that of the single-state decoder and comparable to the proximity decoder. We have demonstrated a novel strategy for dealing with the need to make rapid movements while also maintaining precise cursor control when approaching and stabilizing within targets. Further gains can undoubtedly be realized by optimizing the performance of the individual movement and posture decoders.

Hemodynamic response to exercise and head-up tilt of patients implanted with a rotary blood pump: a computational modeling study.

PubMed

Lim, Einly; Salamonsen, Robert Francis; Mansouri, Mahdi; Gaddum, Nicholas; Mason, David Glen; Timms, Daniel L; Stevens, Michael Charles; Fraser, John; Akmeliawati, Rini; Lovell, Nigel Hamilton

2015-02-01

The present study investigates the response of implantable rotary blood pump (IRBP)-assisted patients to exercise and head-up tilt (HUT), as well as the effect of alterations in the model parameter values on this response, using validated numerical models. Furthermore, we comparatively evaluate the performance of a number of previously proposed physiologically responsive controllers, including constant speed, constant flow pulsatility index (PI), constant average pressure difference between the aorta and the left atrium, constant average differential pump pressure, constant ratio between mean pump flow and pump flow pulsatility (ratioP I or linear Starling-like control), as well as constant left atrial pressure ( P l a ¯ ) control, with regard to their ability to increase cardiac output during exercise while maintaining circulatory stability upon HUT. Although native cardiac output increases automatically during exercise, increasing pump speed was able to further improve total cardiac output and reduce elevated filling pressures. At the same time, reduced venous return associated with upright posture was not shown to induce left ventricular (LV) suction. Although P l a ¯ control outperformed other control modes in its ability to increase cardiac output during exercise, it caused a fall in the mean arterial pressure upon HUT, which may cause postural hypotension or patient discomfort. To the contrary, maintaining constant average pressure difference between the aorta and the left atrium demonstrated superior performance in both exercise and HUT scenarios. Due to their strong dependence on the pump operating point, PI and ratioPI control performed poorly during exercise and HUT. Our simulation results also highlighted the importance of the baroreflex mechanism in determining the response of the IRBP-assisted patients to exercise and postural changes, where desensitized reflex response attenuated the percentage increase in cardiac output during exercise and substantially reduced the arterial pressure upon HUT. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Managing children's postural risk when using mobile technology at home: Challenges and strategies.

PubMed

Ciccarelli, Marina; Chen, Janice D; Vaz, Sharmila; Cordier, Reinie; Falkmer, Torbjörn

2015-11-01

Maintaining the musculoskeletal health of children using mobile information and communication technologies (ICT) at home presents a challenge. The physical environment influences postures during ICT use and can contribute to musculoskeletal complaints. Few studies have assessed postures of children using ICT in home environments. The present study investigated the Rapid Upper Limb Assessment (RULA) scores determined by 16 novice and 16 experienced raters. Each rater viewed 11 videotaped scenarios of a child using two types of mobile ICT at home. The Grand Scores and Action Levels determined by study participants were compared to those of an ergonomist experienced in postural assessment. All postures assessed were rated with an Action Level of 2 or above; representing a postural risk that required further investigation and/or intervention. The sensitivity of RULA to assess some of the unconventional postures adopted by children in the home is questioned. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Postural control and perceptive configuration: influence of expertise in gymnastics.

PubMed

Gautier, Geoffroy; Thouvarecq, Régis; Vuillerme, Nicolas

2008-07-01

The purpose of the present experiment was to investigate how postural adaptations to the perceptive configuration are modified by specific gymnastics experience. Two groups, one expert in gymnastics and the other non-expert, had to maintain the erected posture while optical flow was imposed as follows: 20s motionless, 30s approaching motion, and 20s motionless. The centre of pressure and head displacements were analysed. The postural adaptations were characterised by the variability of movements for the flow conditions and by the postural latencies for the flow transitions. The results showed that the gymnasts tended to minimise their body movements and were more stationary (head) but not more stable (COP) than the non-gymnasts. These results suggest that gymnastics experience develops a specific postural adaptability relative to the perceptive configuration. We conclude that a specific postural experience could be considered as an intrinsic constraint, which leads to modification in the patterns of functional adaptation in the perceptive motor space.

Tai Chi practitioners have better postural control and selective attention in stepping down with and without a concurrent auditory response task.

PubMed

Lu, Xi; Siu, Ka-Chun; Fu, Siu N; Hui-Chan, Christina W Y; Tsang, William W N

2013-08-01

To compare the performance of older experienced Tai Chi practitioners and healthy controls in dual-task versus single-task paradigms, namely stepping down with and without performing an auditory response task, a cross-sectional study was conducted in the Center for East-meets-West in Rehabilitation Sciences at The Hong Kong Polytechnic University, Hong Kong. Twenty-eight Tai Chi practitioners (73.6 ± 4.2 years) and 30 healthy control subjects (72.4 ± 6.1 years) were recruited. Participants were asked to step down from a 19-cm-high platform and maintain a single-leg stance for 10 s with and without a concurrent cognitive task. The cognitive task was an auditory Stroop test in which the participants were required to respond to different tones of voices regardless of their word meanings. Postural stability after stepping down under single- and dual-task paradigms, in terms of excursion of the subject's center of pressure (COP) and cognitive performance, was measured for comparison between the two groups. Our findings demonstrated significant between-group differences in more outcome measures during dual-task than single-task performance. Thus, the auditory Stroop test showed that Tai Chi practitioners achieved not only significantly less error rate in single-task, but also significantly faster reaction time in dual-task, when compared with healthy controls similar in age and other relevant demographics. Similarly, the stepping-down task showed that Tai Chi practitioners not only displayed significantly less COP sway area in single-task, but also significantly less COP sway path than healthy controls in dual-task. These results showed that Tai Chi practitioners achieved better postural stability after stepping down as well as better performance in auditory response task than healthy controls. The improved performance that was magnified by dual motor-cognitive task performance may point to the benefits of Tai Chi being a mind-and-body exercise.

Using data from the Microsoft Kinect 2 to determine postural stability in healthy subjects: A feasibility trial

PubMed Central

Smeragliuolo, Anna H.; Long, John Davis; Bumanlag, Silverio Joseph; He, Victor; Lampe, Anna

2017-01-01

The objective of this study was to determine whether kinematic data collected by the Microsoft Kinect 2 (MK2) could be used to quantify postural stability in healthy subjects. Twelve subjects were recruited for the project, and were instructed to perform a sequence of simple postural stability tasks. The movement sequence was performed as subjects were seated on top of a force platform, and the MK2 was positioned in front of them. This sequence of tasks was performed by each subject under three different postural conditions: “both feet on the ground” (1), “One foot off the ground” (2), and “both feet off the ground” (3). We compared force platform and MK2 data to quantify the degree to which the MK2 was returning reliable data across subjects. We then applied a novel machine-learning paradigm to the MK2 data in order to determine the extent to which data from the MK2 could be used to reliably classify different postural conditions. Our initial comparison of force plate and MK2 data showed a strong agreement between the two devices, with strong Pearson correlations between the trunk centroids “Spine_Mid” (0.85 ± 0.06), “Neck” (0.86 ± 0.07) and “Head” (0.87 ± 0.07), and the center of pressure centroid inferred by the force platform. Mean accuracy for the machine learning classifier from MK2 was 97.0%, with a specific classification accuracy breakdown of 90.9%, 100%, and 100% for conditions 1 through 3, respectively. Mean accuracy for the machine learning classifier derived from the force platform data was lower at 84.4%. We conclude that data from the MK2 has sufficient information content to allow us to classify sequences of tasks being performed under different levels of postural stability. Future studies will focus on validating this protocol on large populations of individuals with actual balance impairments in order to create a toolkit that is clinically validated and available to the medical community. PMID:28196139

Using data from the Microsoft Kinect 2 to determine postural stability in healthy subjects: A feasibility trial.

PubMed

Dehbandi, Behdad; Barachant, Alexandre; Smeragliuolo, Anna H; Long, John Davis; Bumanlag, Silverio Joseph; He, Victor; Lampe, Anna; Putrino, David

2017-01-01

The objective of this study was to determine whether kinematic data collected by the Microsoft Kinect 2 (MK2) could be used to quantify postural stability in healthy subjects. Twelve subjects were recruited for the project, and were instructed to perform a sequence of simple postural stability tasks. The movement sequence was performed as subjects were seated on top of a force platform, and the MK2 was positioned in front of them. This sequence of tasks was performed by each subject under three different postural conditions: "both feet on the ground" (1), "One foot off the ground" (2), and "both feet off the ground" (3). We compared force platform and MK2 data to quantify the degree to which the MK2 was returning reliable data across subjects. We then applied a novel machine-learning paradigm to the MK2 data in order to determine the extent to which data from the MK2 could be used to reliably classify different postural conditions. Our initial comparison of force plate and MK2 data showed a strong agreement between the two devices, with strong Pearson correlations between the trunk centroids "Spine_Mid" (0.85 ± 0.06), "Neck" (0.86 ± 0.07) and "Head" (0.87 ± 0.07), and the center of pressure centroid inferred by the force platform. Mean accuracy for the machine learning classifier from MK2 was 97.0%, with a specific classification accuracy breakdown of 90.9%, 100%, and 100% for conditions 1 through 3, respectively. Mean accuracy for the machine learning classifier derived from the force platform data was lower at 84.4%. We conclude that data from the MK2 has sufficient information content to allow us to classify sequences of tasks being performed under different levels of postural stability. Future studies will focus on validating this protocol on large populations of individuals with actual balance impairments in order to create a toolkit that is clinically validated and available to the medical community.

Effects of stretching and fatigue on peak torque, muscle imbalance, and stability.

PubMed

Costa, Pablo B; Ruas, Cassio V; Smith, Cory M

2018-01-01

The present study examined the acute effects of hamstrings stretching and fatigue on knee extension and flexion peak torque (PT), hamstrings to quadriceps (H:Q) ratio, and postural stability. Seventeen women (mean±SD age=21.8±2.1 years; body mass=63.0±10.5 kg; height=164.7±6.2 cm) and eighteen men (25.8±4.6 years; 83.6±13.2 kg; 175.3±6.0 cm) took part in three laboratory visits. The first visit was a familiarization session, and the subsequent two visits were randomly assigned as a control or stretching condition. For the testing visits, subjects performed a postural stability assessment, stretched (or sat quietly during the control condition), performed a 50-repetition unilateral isokinetic fatigue protocol, and repeated the postural stability assessment. There were no significant differences between control and stretching conditions for initial quadriceps and hamstrings PT, initial H:Q ratio, quadriceps and hamstrings PT fatigue indexes, H:Q ratio Fatigue Index, rating of perceived exertion (RPE), or postural stability (P>0.05). When analyzing 5 intervals of 10 repetitions, significant declines in quadriceps PT were found in all intervals for both conditions (P<0.05). However, a decline in hamstrings PT was only found until the fourth interval (i.e., repetitions 31 to 40) for the stretching condition (P<0.05). Stretching the hamstrings immediately prior to long-duration activities may eventually cause adverse effects in force-generating capacity of this muscle group to occur earlier when fatiguing tasks are involved. Nevertheless, no changes were found for the H:Q ratios after stretching when compared to no-stretching.

Effects of interactive metronome training on postural stability and upper extremity function in Parkinson's disease: a case study.

PubMed

Kim, Arim; Lee, Hye-Sun; Song, Chiang-Soon

2017-01-01

[Purpose] The purpose of this study was to examine the effects of interactive metronome training on the postural stability and upper extremity function of an individual with Parkinson's disease. [Subject and Methods] The participant of this case study was a 75-year-old female with Parkinson's disease diagnosed 7 years prior. This study was a single-subject research with an A-B-A design. She received IM training during the treatment phase (B phase) for 40 minutes per session. She was assessed pretest and posttest using the Berg balance scale and Wolf motor function test, and at baseline and the treatment phase using the measured box-and-block test and a Tetrax system. [Results] After training, the patient's static and dynamic balance, functional activity, and performance time of the upper extremity improved. Interactive metronome therapy improved the manual dexterity of both hands. Interactive metronome therapy also improved the limit of stability of the Parkinson's disease. [Conclusion] Though a case study, the results of this study suggest that IM therapy is effective at restoring the postural stability and upper extremity function of patients with Parkinson's disease.

Effects of interactive metronome training on postural stability and upper extremity function in Parkinson’s disease: a case study

PubMed Central

Kim, Arim; Lee, Hye-Sun; Song, Chiang-Soon

2017-01-01

[Purpose] The purpose of this study was to examine the effects of interactive metronome training on the postural stability and upper extremity function of an individual with Parkinson’s disease. [Subject and Methods] The participant of this case study was a 75-year-old female with Parkinson’s disease diagnosed 7 years prior. This study was a single-subject research with an A-B-A design. She received IM training during the treatment phase (B phase) for 40 minutes per session. She was assessed pretest and posttest using the Berg balance scale and Wolf motor function test, and at baseline and the treatment phase using the measured box-and-block test and a Tetrax system. [Results] After training, the patient’s static and dynamic balance, functional activity, and performance time of the upper extremity improved. Interactive metronome therapy improved the manual dexterity of both hands. Interactive metronome therapy also improved the limit of stability of the Parkinson’s disease. [Conclusion] Though a case study, the results of this study suggest that IM therapy is effective at restoring the postural stability and upper extremity function of patients with Parkinson’s disease. PMID:28210066

Cognition and balance control: does processing of explicit contextual cues of impending perturbations modulate automatic postural responses?

PubMed

Coelho, Daniel Boari; Teixeira, Luis Augusto

2017-08-01

Processing of predictive contextual cues of an impending perturbation is thought to induce adaptive postural responses. Cueing in previous research has been provided through repeated perturbations with a constant foreperiod. This experimental strategy confounds explicit predictive cueing with adaptation and non-specific properties of temporal cueing. Two experiments were performed to assess those factors separately. To perturb upright balance, the base of support was suddenly displaced backwards in three amplitudes: 5, 10 and 15 cm. In Experiment 1, we tested the effect of cueing the amplitude of the impending postural perturbation by means of visual signals, and the effect of adaptation to repeated exposures by comparing block versus random sequences of perturbation. In Experiment 2, we evaluated separately the effects of cueing the characteristics of an impending balance perturbation and cueing the timing of perturbation onset. Results from Experiment 1 showed that the block sequence of perturbations led to increased stability of automatic postural responses, and modulation of magnitude and onset latency of muscular responses. Results from Experiment 2 showed that only the condition cueing timing of platform translation onset led to increased balance stability and modulation of onset latency of muscular responses. Conversely, cueing platform displacement amplitude failed to induce any effects on automatic postural responses in both experiments. Our findings support the interpretation of improved postural responses via optimized sensorimotor processes, at the same time that cast doubt on the notion that cognitive processing of explicit contextual cues advancing the magnitude of an impending perturbation can preset adaptive postural responses.

Study I: effects of 0.06% and 0.10% blood alcohol concentration on human postural control.

PubMed

Modig, F; Patel, M; Magnusson, M; Fransson, P A

2012-03-01

Alcohol intoxication causes many accidental falls presented at emergency departments, with the injury severity often related to level of blood alcohol concentration (BAC). One way to evaluate the decline in postural control and the fall risk is to assess standing stability when challenged. The study objective was to comprehensively investigate alcohol-related impairments on postural control and adaptive motor learning at specific BAC levels. Effects of alcohol intoxication at 0.06% and 0.10% BAC were examined with posturography when unperturbed or perturbed by calf vibration. Twenty-five participants (mean age 25.1 years) were investigated standing with either eyes open or closed. Our results revealed several significant findings: (1) stability declined much faster from alcohol intoxication between 0.06% and 0.10% BAC (60-140%) compared with between 0.0% and 0.06% BAC (30%); (2) sustained exposure to repeated balance perturbations augmented the alcohol-related destabilization; (3) there were stronger effects of alcohol intoxication on stability in lateral direction than in anteroposterior direction; and (4) there was a gradual degradation of postural control particularly in lateral direction when the balance perturbations were repeated at 0.06% and 0.10% BAC, indicating adaptation deficits when intoxicated. To summarize, alcohol has profound deteriorating effects on human postural control, which are dose dependent, time dependent and direction specific. The maximal effects of alcohol intoxication on physiological performance might not be evident initially, but may be revealed first when under sustained sensory-motor challenges. Copyright © 2011 Elsevier B.V. All rights reserved.

Effectuation of adaptive stability and postural alignment strategies are decreased by alcohol intoxication.

PubMed

Hafström, A; Modig, F; Magnusson, M; Fransson, P A

2014-06-01

Human stability control is a complex process comprising contributions from several partly independent mechanisms such as coordination, feedback and feed-forward control, and adaptation. Acute alcohol intoxication impairs these functions and is recognized as a major contributor to fall traumas. The study aimed to investigate how alcohol intoxication at .06% and .10% blood alcohol concentration (BAC) affected the movement spans and control of posture alignment. The angular positions of the head, shoulder, hip and knees relative to the ankles were measured with a 3D motion analysis system in 25 healthy adults during standing with eyes open or closed and with or without vibratory balance perturbations. Alcohol intoxication significantly increased the movement spans of the head, shoulders, hip and knees in anteroposterior and lateral directions during quiet stance (p < or = .047 and p < or = .003) and balance perturbations (p<.001, both directions). Alcohol intoxication also decreased the ability to reduce the movement spans through adaptation in both anteroposterior (p < or = .011) and lateral (p < or = .004) directions. When sober and submitted to balance perturbations, the subjects aligned the head, shoulders, hip and knees more forward relative to the ankle joint (p < .001), hence adopting a more resilient posture increasing the safety margin for backward falls. Alcohol intoxication significantly delayed this forward realignment (p < or = .022). Alcohol intoxication did not cause any significant posture realignment in the lateral direction. Thus, initiation of adaptive posture realignments to alcohol or other disruptions might be context dependent and associated with reaching a certain level of stability threats. Copyright © 2014 Elsevier B.V. All rights reserved.

Postural perturbations: new insights for treatment of balance disorders

NASA Technical Reports Server (NTRS)

Horak, F. B.; Henry, S. M.; Shumway-Cook, A.; Peterson, B. W. (Principal Investigator)

1997-01-01

This article reviews the neural control of posture as understood through studies of automatic responses to mechanical perturbations. Recent studies of responses to postural perturbations have provided a new view of how postural stability is controlled, and this view has profound implications for physical therapy practice. We discuss the implications for rehabilitation of balance disorders and demonstrate how an understanding of the specific systems underlying postural control can help to focus and enrich our therapeutic approaches. By understanding the basic systems underlying control of balance, such as strategy selection, rapid latencies, coordinated temporal spatial patterns, force control, and context-specific adaptations, therapists can focus their treatment on each patient's specific impairments. Research on postural responses to surface translations has shown that balance is not based on a fixed set of equilibrium reflexes but on a flexible, functional motor skill that can adapt with training and experience. More research is needed to determine the extent to which quantification of automatic postural responses has practical implications for predicting falls in patients with constraints in their postural control system.

Resolving Sensory Conflict: the Effect of Muscle Vibration on Postural Stability

NASA Technical Reports Server (NTRS)

Layne, Charles S.

1991-01-01

The otolith-tilt reinterpretation hypothesis (OTTR) proposes that the central nervous system adapts to weightlessness by reinterpreting all otolith input as linear motion. While interpreting otolith input exclusively as linear motion is functionally useful in space, it is maladaptive upon return to Earth. Astronauts have reported experiencing illusory sensations during head movement which contributes to postural instability. The effect is assessed of muscle vibration in combination with a variety of sensory conflicts on postural equilibrium. The equilibrium of six healthy subjects was tested using the EquiTest sensory test protocol, with and without the confounding influence of triceps surea vibration. The data were analyzed with repeated measures with vibration, vision status, and platform status as independent variables. All main effects and an interaction between the presence of vision and platform sway referencing were found to be significant. Overall, a 4.5 pct. decrease in postural stability was observed with vibration. The trend of the difference scores between conditions with and without vibration suggests that vibration is most destabilizing when the triceps surea is able to change length during postural sway (i.e., conditions with a fixed support surface). The impact of sway referencing vision was virtually identical to that of eye closure, providing compelling evidence that sway referencing 'nulls out' useful cues about subject sway.

Postural Control in Young People with Visual Impairments and Various Risks of Falls

ERIC Educational Resources Information Center

Sadowska, Dorota; Stemplewski, Rafal; Szeklicki, Robert

2017-01-01

Introduction: Early diagnosis of postural control deficiencies facilitates implementation of an individual rehabilitation plan to prevent falls. The aim of the study was to assess the risk of falling in individuals with visual impairments, and to compare performance-based and theoretical limits of stability in subjects with various risks of…

Stochastic analysis of motor-control stability, polymer based force sensing, and optical stimulation as a preventive measure for falls

NASA Astrophysics Data System (ADS)

Landrock, Clinton K.

Falls are the leading cause of all external injuries. Outcomes of falls include the leading cause of traumatic brain injury and bone fractures, and high direct medical costs in the billions of dollars. This work focused on developing three areas of enabling component technology to be used in postural control monitoring tools targeting the mitigation of falls. The first was an analysis tool based on stochastic fractal analysis to reliably measure levels of motor control. The second focus was on thin film wearable pressure sensors capable of relaying data for the first tool. The third was new thin film advanced optics for improving phototherapy devices targeting postural control disorders. Two populations, athletes and elderly, were studied against control groups. The results of these studies clearly show that monitoring postural stability in at-risk groups can be achieved reliably, and an integrated wearable system can be envisioned for both monitoring and treatment purposes. Keywords: electro-active polymer, ionic polymer-metal composite, postural control, motor control, fall prevention, sports medicine, fractal analysis, physiological signals, wearable sensors, phototherapy, photobiomodulation, nano-optics.

THE RELATIONSHIP BETWEEN VARIOUS MODES OF SINGLE LEG POSTURAL CONTROL ASSESSMENT

PubMed Central

Schmitz, Randy

2012-01-01

Purpose/Background: While various techniques have been developed to assess the postural control system, little is known about the relationship between single leg static and functional balance. The purpose of the current study was to determine the relationship between the performance measures of several single leg postural stability tests. Methods: Forty six recreationally active college students (17 males, 29 females, 21±3 yrs, 173±10 cm) performed six single leg tests in a counterbalanced order: 1) Firm Surface-Eyes Open, 2) Firm Surface-Eyes Closed, 3) Multiaxial Surface-Eyes Open, 4) Multiaxial Surface-Eyes Closed, 5) Star Excursion Balance Test (posterior medial reach), 6) Single leg Hop-Stabilization Test. Bivariate correlations were conducted between the six outcome variables. Results: Mild to moderate correlations existed between the static tests. No significant correlations existed involving either of the functional tests. Conclusions: The results indicate that while performance of static balance tasks are mildly to moderately related, they appear to be unrelated to functional reaching or hopping movements, supporting the utilization of a battery of tests to determine overall postural control performance. Level of Evidence: 3b PMID:22666640

Neuropathological aspects of conservative treatment of scoliosis. A theoretical view point.

PubMed

Czupryna, Krzysztof; Nowotny-Czupryna, Olga; Nowotny, Janusz

2012-01-01

An upright body posture cannot be maintained passively for reasons including a high location of the centre of gravity (COG) and a small support area. Proper alignment of body parts is maintained automatically, tending towards a pattern encoded in the CNS. A particularly important role in posture regulation is played by the short muscles of the back, which respond to being stretched with a contraction. During the early phase of scoliosis, the CNS automatically corrects abnormalities, but over time habituation occurs and the CNS treats them as something normal. Any attempt to restore proper body alignment is treated as an error and CNS automatically restores this abnormal pattern. With a prolonged deviation in body part alignment, CNS treats it as a defect and runs compensatory mechanisms to restore the balance of the body as a whole. Balance is ensured by postural compensation, but this does not restore proper body part alignment. In the treatment of scoliosis, it is important both to slow down progression and to prevent the development of abnormal postural habits, which are part of a vicious circle even without progression. Secondary prevention is therefore needed in all patients. Passive observation limits the possibilities for prevention and contradicts the principle of early implementation of rehabilitation. Depending on the size of the angle of curvature, recommended treatments of scoliosis comprise observation, corset bracing, and surgery. Physiotherapy is often treated as an unconventional and ineffective treatment. Often, the biggest problem is transferring the resulting correction to automatic maintenance of a correct posture in the vertical position. The aim of this paper was to discuss the conservative treatment of scoliosis with regard to difficulties maintaining the correct alignment of the body parts in the vertical position that accompany scoliosis.

The effects of a high-intensity free-weight back-squat exercise protocol on postural stability in resistance-trained males.

PubMed

Thiele, R M; Conchola, E C; Palmer, T B; DeFreitas, J M; Thompson, B J

2015-01-01

The purpose of this study was to investigate the effects of a high-intensity free-weight back-squat exercise on postural stability characteristics in resistance-trained males. Eighteen college-aged (mean ± SD: age = 22.9 ± 2.9 years; height = 175.8 ± 6.4 cm; mass = 86.3 ± 9.3 kg), resistance-trained males performed postural stability testing before and after completing five sets of eight repetitions of back-squat exercises at 80% of one-repetition maximum. A commercial balance testing device was used to assess sway index at pre- and at 0, 5, 10, 15 and 20 min post-exercise. Each balance assessment consisted of four, 20-s static stance conditions: eyes-open firm surface, eyes-closed firm surface, eyes-open soft surface and eyes-closed soft surface. Sway index was greater (P = 0.001-0.020) at Post 0 than at all other time points. No differences (P > 0.05) were observed between any other time phases. Sway index was greater (P < 0.001) for eyes-closed soft surface than all other conditions. These findings revealed sway index for all conditions significantly increased following completion of the back-squat; however, sway index recovered within 5 min of exercise. Higher sway index values as a result of neuromuscular fatigue induced by a back-squat exercise may have performance and injury risk consequences to subsequent activities that rely on postural stability. However, these findings suggest balance impairments may recover in ~5 min following high-intensity lower body resistance exercise.

Specificity of Postural Sway to the Demands of a Precision Task at Sea

ERIC Educational Resources Information Center

Chen, Fu-Chen; Stoffregen, Thomas A.

2012-01-01

Mariners actively adjust their body orientation in response to ship motion. On a ship at sea, we evaluated relations between standing postural activity and the performance of a precision aiming task. Standing participants (experienced mariners) maintained the beam from a handheld laser on a target. Targets were large or small, thereby varying the…

The postural stability of children with foetal alcohol spectrum disorders during one-leg stance: A feasibility study

PubMed Central

2018-01-01

Background Postural control may be impaired in children with foetal alcohol spectrum disorders (FASD). The study assessed the protocol feasibility in terms of (1) recruiting children with FASD in a rural, small town; (2) using the measurement instruments in a real-life setting; (3) the one-leg standing (OLS) task and (4) presenting preliminary results on postural stability of children with and without FASD. Methods Nine-year-old children diagnosed with and without FASD were invited to participate. Twenty-eight children performed OLS. Feasibility outcomes included recruitment, measurement instrument use and task instruction. Postural stability outcomes included standing duration, centre of pressure (COP) and body segment acceleration. Results Participants recruitment was feasible in terms of the (1) ability to sample a reasonable participant number in a rural town setting and the capacity to increase the sample size if more schools are included in the sampling frame and (2) use of assent and consent forms that were appropriate for this population. The measurement instruments were user-friendly, cost-effective and time-efficient. Instructions for the task require amendment to address foot placement of the non-weight–bearing leg. There was a significant difference between cases and controls on mean COP velocity (p = 0.001) and the pelvis segment acceleration in the mediolateral direction (p = 0.01) and the anteroposterior direction (p = 0.027). The control children took longer to achieve postural control. The girls demonstrated a significant difference for the COP anteroposterior displacement (p = 0.008) and velocity (p = 0.049). Conclusions The recruitment of children with and without FASD in a rural, small town and the administration of measurement instruments in a real-life, school-based setting was feasible. However, the verbal instructions for the task require revision. The male control group took longer to achieve postural control because the task was performed differently between the two groups. However, the case girls were slower to achieve postural control than control girls though performing the task similarly. PMID:29707515

Mechanical evidence that flamingos can support their body on one leg with little active muscular force.

PubMed

Chang, Young-Hui; Ting, Lena H

2017-05-01

Flamingos (Phoenicopteridae) often stand and sleep on one leg for long periods, but it is unknown how much active muscle contractile force they use for the mechanical demands of standing on one leg: body weight support and maintaining balance. First, we demonstrated that flamingo cadavers could passively support body weight on one leg without any muscle activity while adopting a stable, unchanging, joint posture resembling that seen in live flamingos. By contrast, the cadaveric flamingo could not be stably held in a two-legged pose, suggesting a greater necessity for active muscle force to stabilize two-legged versus one-legged postures. Our results suggest that flamingos engage a passively engaged gravitational stay apparatus (proximally located) for weight support during one-legged standing. Second, we discovered that live flamingos standing on one leg have markedly reduced body sway during quiescent versus alert behaviours, with the point of force application directly under the distal joint, reducing the need for muscular joint torque. Taken together, our results highlight the possibility that flamingos stand for long durations on one leg without exacting high muscular forces and, thus, with little energetic expenditure. © 2017 The Author(s).

Trunk, head, and step characteristics during normal and narrow-based walking under deteriorated sensory conditions.

PubMed

Deshpande, Nandini; Zhang, Fang

2014-01-01

The ability to maintain stability in the frontal plane (medialateral direction) while walking is commonly included as a component of motor performance assessment. Postural control in the frontal plane may deteriorate faster and earlier with increasing age, compared to that in the sagittal plane (anteroposterior direction). Fifteen young (20-30 years old) and 15 older (>65 years old) healthy participants were recruited to investigate age-related differences in postural control during the normal and narrow-based walking when performed under suboptimal vestibular and lower limb somatosensory conditions achieved by galvanic stimulation and compliant surfaces, respectively. Gait speed decreased in the narrow-based walking condition, with larger decrease in the elderly (by 6%). In the elderly head roll increased with perturbed vestibular information in impaired somatosensory condition (by 40.70%). In both age groups trunk roll increased under impaired somatosensation in the narrow-based walking condition (by 43.62%) but not in normal walking condition. Older participants adopted a more cautious strategy characterized by lower walking speed when walking on a narrow base and exhibited deteriorated integrative ability of the CNS for head control. Accurate lower limb somatosensation may play a critical role in narrow-based walking.

A research on the postural stability of a person wearing the lower limb exoskeletal robot by the HAT model.

PubMed

Chang, Minsu; Kim, Yeongmin; Lee, Yoseph; Jeon, Doyoung

2017-07-01

This paper proposes a method of detecting the postural stability of a person wearing the lower limb exoskeletal robot with the HAT(Head-Arm-Trunk) model. Previous studies have shown that the human posture is stable when the CoM(Center of Mass) of the human body is placed on the BoS(Base of Support). In the case of the lower limb exoskeletal robot, the motion data, which are used for the CoM estimation, are acquired by sensors in the robot. The upper body, however, does not have sensors in each segment so that it may cause the error of the CoM estimation. In this paper, the HAT(Head-Arm-Trunk) model which combines head, arms, and torso into a single segment is considered because the motion of head and arms are unknown due to the lack of sensors. To verify the feasibility of HAT model, the reflecting markers are attached to each segment of the whole human body and the exact motion data are acquired by the VICON to compare the COM of the full body model and HAT model. The difference between the CoM with full body and that with HAT model is within 20mm for the various motions of head and arms. Based on the HAT model, the XCoM(Extrapolated Center of Mass) which includes the velocity of the CoM is used for prediction of the postural stability. The experiment of making unstable posture shows that the XCoM of the whole body based on the HAT model is feasible to detect the instance of postural instability earlier than the CoM by 20-250 msec. This result may be used for the lower limb exoskeletal robot to prepare for any action to prevent the falling down.

The Effect of a Short-Term and Long-Term Whole-Body Vibration in Healthy Men upon the Postural Stability

PubMed Central

Piecha, Magdalena; Juras, Grzegorz; Król, Piotr; Sobota, Grzegorz; Polak, Anna; Bacik, Bogdan

2014-01-01

The study aimed to establish the short-term and long-term effects of whole-body vibration on postural stability. The sample consisted of 28 male subjects randomly allocated to four comparative groups, three of which exercised on a vibration platform with parameters set individually for the groups. The stabilographic signal was recorded before the test commenced, after a single session of whole-body vibration, immediately after the last set of exercises of the 4-week whole-body vibration training, and one week after the training ended. The subjects were exposed to vibrations 3 times a week for 4 weeks. Long-term vibration training significantly shortened the rambling and trembling paths in the frontal plane. The path lengths were significantly reduced in the frontal plane one week after the training end date. Most changes in the values of the center of pressure (COP) path lengths in the sagittal and frontal plane were statistically insignificant. We concluded that long-term vibration training improves the postural stability of young healthy individuals in the frontal plane. PMID:24520362

The effect of Pilates based exercise on mobility, postural stability, and balance in order to decrease fall risk in older adults.

PubMed

Pata, Rachel W; Lord, Katrina; Lamb, Jamie

2014-07-01

Falls are a common problem in older adults. Impaired balance, mobility and postural stability are risk factors for falling. Limited research has been performed on Pilates exercise and the ability to decrease fall risk. In this quasi-experimental study, 35 adults (61-87 years old) participated in an 8-week Pilates based exercise program. Blind examiners conducted the Timed Up and Go (TUG), Forward Reach Test, and Turn 180 Test before and after the intervention. Number of falls, perception of Pilates, and fear of falling was also recorded. Thirty-two (91.4%) participants completed post-test measures. Significant improvements were seen in the TUG (p <0.001) and Turn 180 Test (p = 0.002). Improvements were also demonstrated in the Forward Reach Test (p = 0.049). A positive perception of the Pilates program and decreased fear of falling was shown. Results suggest a Pilates based exercise program may be effective in improving balance, mobility and postural stability to decrease fall risk. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of a cognitive dual task on variability and local dynamic stability in sustained repetitive arm movements using principal component analysis: a pilot study.

PubMed

Longo, Alessia; Federolf, Peter; Haid, Thomas; Meulenbroek, Ruud

2018-06-01

In many daily jobs, repetitive arm movements are performed for extended periods of time under continuous cognitive demands. Even highly monotonous tasks exhibit an inherent motor variability and subtle fluctuations in movement stability. Variability and stability are different aspects of system dynamics, whose magnitude may be further affected by a cognitive load. Thus, the aim of the study was to explore and compare the effects of a cognitive dual task on the variability and local dynamic stability in a repetitive bimanual task. Thirteen healthy volunteers performed the repetitive motor task with and without a concurrent cognitive task of counting aloud backwards in multiples of three. Upper-body 3D kinematics were collected and postural reconfigurations-the variability related to the volunteer's postural change-were determined through a principal component analysis-based procedure. Subsequently, the most salient component was selected for the analysis of (1) cycle-to-cycle spatial and temporal variability, and (2) local dynamic stability as reflected by the largest Lyapunov exponent. Finally, end-point variability was evaluated as a control measure. The dual cognitive task proved to increase the temporal variability and reduce the local dynamic stability, marginally decrease endpoint variability, and substantially lower the incidence of postural reconfigurations. Particularly, the latter effect is considered to be relevant for the prevention of work-related musculoskeletal disorders since reduced variability in sustained repetitive tasks might increase the risk of overuse injuries.

The internal representation of head orientation differs for conscious perception and balance control.

PubMed

Dalton, Brian H; Rasman, Brandon G; Inglis, J Timothy; Blouin, Jean-Sébastien

2017-04-15

We tested perceived head-on-feet orientation and the direction of vestibular-evoked balance responses in passively and actively held head-turned postures. The direction of vestibular-evoked balance responses was not aligned with perceived head-on-feet orientation while maintaining prolonged passively held head-turned postures. Furthermore, static visual cues of head-on-feet orientation did not update the estimate of head posture for the balance controller. A prolonged actively held head-turned posture did not elicit a rotation in the direction of the vestibular-evoked balance response despite a significant rotation in perceived angular head posture. It is proposed that conscious perception of head posture and the transformation of vestibular signals for standing balance relying on this head posture are not dependent on the same internal representation. Rather, the balance system may operate under its own sensorimotor principles, which are partly independent from perception. Vestibular signals used for balance control must be integrated with other sensorimotor cues to allow transformation of descending signals according to an internal representation of body configuration. We explored two alternative models of sensorimotor integration that propose (1) a single internal representation of head-on-feet orientation is responsible for perceived postural orientation and standing balance or (2) conscious perception and balance control are driven by separate internal representations. During three experiments, participants stood quietly while passively or actively maintaining a prolonged head-turned posture (>10 min). Throughout the trials, participants intermittently reported their perceived head angular position, and subsequently electrical vestibular stimuli were delivered to elicit whole-body balance responses. Visual recalibration of head-on-feet posture was used to determine whether static visual cues are used to update the internal representation of body configuration for perceived orientation and standing balance. All three experiments involved situations in which the vestibular-evoked balance response was not orthogonal to perceived head-on-feet orientation, regardless of the visual information provided. For prolonged head-turned postures, balance responses consistent with actual head-on-feet posture occurred only during the active condition. Our results indicate that conscious perception of head-on-feet posture and vestibular control of balance do not rely on the same internal representation, but instead treat sensorimotor cues in parallel and may arrive at different conclusions regarding head-on-feet posture. The balance system appears to bypass static visual cues of postural orientation and mainly use other sensorimotor signals of head-on-feet position to transform vestibular signals of head motion, a mechanism appropriate for most daily activities. © 2016 The Authors. The Journal of Physiology © 2016 The Physiological Society.

Undisturbed upright stance control in the elderly: Part 1. Age-related changes in undisturbed upright stance control.

PubMed

Berger, L; Chuzel, M; Buisson, G; Rougier, P

2005-09-01

The authors investigated age-related changes in postural control in 33 healthy young adults (18-31 years), 29 seniors (62-75 years), and 22 elderly people (75-96 years). A force platform recorded the results. The horizontal motions of the center of gravity (CGh) and their difference in the plane of support CP - CGv were deduced from the complex center of pressure (CP) trajectories. With fractional Brownian modeling, one can establish that the aging process seems to induce a transition phase in which seniors take more time to initiate the corrective process in the mediolateral (ML) axis than do younger people. The elderly develop a new strategy characterized by the mobilization of higher neuromuscular energy to maintain equilibrium. In the ML axis, the larger displacements could be caused mainly by a hip strategy that could facilitate step initiation. In the anteroposterior (AP) axis, seniors and elderly individuals maintain a relative ability to stabilize their CG into the base of support compared with younger people.

Comparison of standing postural control and gait parameters in people with and without chronic low back pain: a cross-sectional case-control study.

PubMed

MacRae, Catharine Siân; Critchley, Duncan; Lewis, Jeremy S; Shortland, Adam

2018-01-01

Differences in postural control and gait have been identified between people with and without chronic low back pain (CLBP); however, many previous studies present data from small samples, or have used methodologies with questionable reliability. This study, employing robust methodology, hypothesised that there would be a difference in postural control, and spatiotemporal parameters of gait in people with CLBP compared with asymptomatic individuals. This cross-sectional case-control study age-matched and gender-matched 16 CLBP and 16 asymptomatic participants. Participants were assessed barefoot (1) standing, over three 40 s trials, under four posture challenging conditions (2) during gait. Primary outcome was postural stability (assessed by root mean squared error of centre of pressure (CoP) displacement (CoP RMSEAP ) and mean CoP velocity (CoP VELAP ), both in the anteroposterior direction); gait outcomes were hip range of movement and peak moments, walking speed, cadence and stride length, assessed using force plates and a motion analysis system. There were no differences between groups in CoP RMSEAP (P=0.26), or CoP VELAP (P=0.60) for any standing condition. During gait, no differences were observed between groups for spatiotemporal parameters, maximum, minimum and total ranges of hip movement, or peak hip flexor or extensor moments in the sagittal plane. In contrast to previous research, this study suggests that people with mild to moderate CLBP present with similar standing postural control, and parameters of gait to asymptomatic individuals. Treatments directed at influencing postural stability (eg, standing on a wobble board) or specific parameters of gait may be an unnecessary addition to a treatment programme.

Anticipatory postural adjustments and anticipatory synergy adjustments: Preparing to a postural perturbation with predictable and unpredictable direction

PubMed Central

Piscitelli, Daniele; Falaki, Ali; Solnik, Stanislaw; Latash, Mark L.

2016-01-01

We explored two aspects of feed-forward postural control, anticipatory postural adjustments (APAs) and anticipatory synergy adjustments (ASAs) seen prior to self-triggered unloading with known and unknown direction of the perturbation. In particular, we tested two main hypotheses predicting contrasting changes in APAs and ASAs. The first hypothesis predicted no major changes in ASAs. The second hypothesis predicted delayed APAs with predominance of co-contraction patterns when perturbation direction was unknown. Healthy subjects stood on the force plate and help a bar with two loads acting in the forward and backward directions. They pressed a trigger that released one of the loads causing a postural perturbation. In different series, the direction of the perturbation was either known (the same load released in all trials) or unknown (the subjects did not know which of the two loads would be released). Surface electromyograms were recorded and used to quantify APAs, synergies stabilizing center of pressure coordinate (within the uncontrolled manifold hypothesis), and ASA. APAs and ASAs were seen in all conditions. APAs were delayed and predominance of co-contraction patterns was seen under the conditions with unpredictable direction of perturbation. In contrast, no significant changes in synergies and ASAs were seen. Overall, these results show that feed-forward control of vertical posture has two distinct components, reflected in APAs and ASAs, which show qualitatively different adjustments with changes in predictability of the direction of perturbation. These results are interpreted within the recently proposed hierarchical scheme of the synergic control of motor tasks. The observations underscore the complexity of the feed-forward postural control, which involves separate changes in salient performance variables (such as coordinate of the center of pressure) and in their stability properties. PMID:27866261

Anticipatory postural adjustments and anticipatory synergy adjustments: preparing to a postural perturbation with predictable and unpredictable direction.

PubMed

Piscitelli, Daniele; Falaki, Ali; Solnik, Stanislaw; Latash, Mark L

2017-03-01

We explored two aspects of feed-forward postural control, anticipatory postural adjustments (APAs) and anticipatory synergy adjustments (ASAs) seen prior to self-triggered unloading with known and unknown direction of the perturbation. In particular, we tested two main hypotheses predicting contrasting changes in APAs and ASAs. The first hypothesis predicted no major changes in ASAs. The second hypothesis predicted delayed APAs with predominance of co-contraction patterns when perturbation direction was unknown. Healthy subjects stood on the force plate and held a bar with two loads acting in the forward and backward directions. They pressed a trigger that released one of the loads causing a postural perturbation. In different series, the direction of the perturbation was either known (the same load released in all trials) or unknown (the subjects did not know which of the two loads would be released). Surface electromyograms were recorded and used to quantify APAs, synergies stabilizing center of pressure coordinate (within the uncontrolled manifold hypothesis), and ASA. APAs and ASAs were seen in all conditions. APAs were delayed, and predominance of co-contraction patterns was seen under the conditions with unpredictable direction of perturbation. In contrast, no significant changes in synergies and ASAs were seen. Overall, these results show that feed-forward control of vertical posture has two distinct components, reflected in APAs and ASAs, which show qualitatively different adjustments with changes in predictability of the direction of perturbation. These results are interpreted within the recently proposed hierarchical scheme of the synergic control of motor tasks. The observations underscore the complexity of the feed-forward postural control, which involves separate changes in salient performance variables (such as coordinate of the center of pressure) and in their stability properties.

Older adults prioritize postural stability in the anterior-posterior direction to regain balance following volitional lateral step.

PubMed

Porter, Shaun; Nantel, Julie

2015-02-01

Postural control in the medial-lateral (ML) direction is of particular interest regarding the assessment of changes in postural control, as it is highly related to the risk of falling. To determine the postural strategies used to regain balance following a voluntary lateral step and compare these strategies between young and older adults. Sixteen older adults (60-90 years) and 14 young adults (20-40 years) were asked to stand quietly for 30s, walk in place and then take a lateral step and stand quietly (30s). Balance Post was divided into 10s intervals. Center of pressure displacement (CoP) and velocity (VCoP) in the anterio-posterior (AP) and ML directions were analyzed. In both groups, CoP and VCoP in AP and ML increased in Post1 compared to Pre (P<0.001). Dissimilar to young adults, VCoP-Post2, Post3 ML were larger than Pre (P=0.01) in older adults. Age correlated with all VCoP (Pre and Post) in both ML (P<0.05) and AP directions (P<0.01). Dissimilar to young adults, older adults use different postural strategies in ML and AP directions and prioritized postural stability in the AP direction to recover balance after completing a lateral step. In the ML direction, older adults took up to 30s to regain balance. Considering that age was related to larger CoP displacement and velocity, the AP strategy to recover postural balance following a lateral step could become less efficient as older adults age and therefore increasing the risk of falls. Copyright © 2015 Elsevier B.V. All rights reserved.

Balance control during gait initiation: State-of-the-art and research perspectives.

PubMed

Yiou, Eric; Caderby, Teddy; Delafontaine, Arnaud; Fourcade, Paul; Honeine, Jean-Louis

2017-11-18

It is well known that balance control is affected by aging, neurological and orthopedic conditions. Poor balance control during gait and postural maintenance are associated with disability, falls and increased mortality. Gait initiation - the transient period between the quiet standing posture and steady state walking - is a functional task that is classically used in the literature to investigate how the central nervous system (CNS) controls balance during a whole-body movement involving change in the base of support dimensions and center of mass progression. Understanding how the CNS in able-bodied subjects exerts this control during such a challenging task is a pre-requisite to identifying motor disorders in populations with specific impairments of the postural system. It may also provide clinicians with objective measures to assess the efficiency of rehabilitation programs and better target interventions according to individual impairments. The present review thus proposes a state-of-the-art analysis on: (1) the balance control mechanisms in play during gait initiation in able bodied subjects and in the case of some frail populations; and (2) the biomechanical parameters used in the literature to quantify dynamic stability during gait initiation. Balance control mechanisms reviewed in this article included anticipatory postural adjustments, stance leg stiffness, foot placement, lateral ankle strategy, swing foot strike pattern and vertical center of mass braking. Based on this review, the following viewpoints were put forward: (1) dynamic stability during gait initiation may share a principle of homeostatic regulation similar to most physiological variables, where separate mechanisms need to be coordinated to ensure stabilization of vital variables, and consequently; and (2) rehabilitation interventions which focus on separate or isolated components of posture, balance, or gait may limit the effectiveness of current clinical practices.

Balance control during gait initiation: State-of-the-art and research perspectives

PubMed Central

Yiou, Eric; Caderby, Teddy; Delafontaine, Arnaud; Fourcade, Paul; Honeine, Jean-Louis

2017-01-01

It is well known that balance control is affected by aging, neurological and orthopedic conditions. Poor balance control during gait and postural maintenance are associated with disability, falls and increased mortality. Gait initiation - the transient period between the quiet standing posture and steady state walking - is a functional task that is classically used in the literature to investigate how the central nervous system (CNS) controls balance during a whole-body movement involving change in the base of support dimensions and center of mass progression. Understanding how the CNS in able-bodied subjects exerts this control during such a challenging task is a pre-requisite to identifying motor disorders in populations with specific impairments of the postural system. It may also provide clinicians with objective measures to assess the efficiency of rehabilitation programs and better target interventions according to individual impairments. The present review thus proposes a state-of-the-art analysis on: (1) the balance control mechanisms in play during gait initiation in able bodied subjects and in the case of some frail populations; and (2) the biomechanical parameters used in the literature to quantify dynamic stability during gait initiation. Balance control mechanisms reviewed in this article included anticipatory postural adjustments, stance leg stiffness, foot placement, lateral ankle strategy, swing foot strike pattern and vertical center of mass braking. Based on this review, the following viewpoints were put forward: (1) dynamic stability during gait initiation may share a principle of homeostatic regulation similar to most physiological variables, where separate mechanisms need to be coordinated to ensure stabilization of vital variables, and consequently; and (2) rehabilitation interventions which focus on separate or isolated components of posture, balance, or gait may limit the effectiveness of current clinical practices. PMID:29184756

The effects of narrow and elevated path walking on aperture crossing.

PubMed

Hackney, Amy L; Cinelli, Michael E; Denomme, Luke T; Frank, James S

2015-06-01

The study investigated the impact that action capabilities have on identifying possibilities for action, particularly how postural threat influences the passability of apertures. To do this, the ability to maintain balance was challenged by manipulating the level of postural threat while walking. First, participants walked along a 7m path and passed through two vertical obstacles spaced 1.1-1.5×the shoulder width apart during normal walking. Next, postural threat was manipulated by having participants complete the task either walking on a narrow, ground level path or on an elevated/narrow path. Despite a decrease in walking speed as well as an increase in trunk sway in both the narrow and elevated/narrow walking conditions, the passability of apertures was only affected when the consequence of instability was greatest. In the elevated/narrow walking condition, individuals maintained a larger critical point (rotated their shoulders for larger aperture widths) compared to normal walking. However, this effect was not observed for the narrow path walking suggesting that the level of postural threat was not enough to impose similar changes to the critical point. Therefore, it appears that manipulating action capabilities by increasing postural threat does indeed influence aperture crossing behavior, however the consequence associated with instability must be high before both gait characteristics and the critical point are affected. Copyright © 2015 Elsevier B.V. All rights reserved.

Kinect-Based Virtual Game for the Elderly that Detects Incorrect Body Postures in Real Time

PubMed Central

Saenz-de-Urturi, Zelai; Garcia-Zapirain Soto, Begonya

2016-01-01

Poor posture can result in loss of physical function, which is necessary to preserving independence in later life. Its decline is often the determining factor for loss of independence in the elderly. To avoid this, a system to correct poor posture in the elderly, designed for Kinect-based indoor applications, is proposed in this paper. Due to the importance of maintaining a healthy life style in senior citizens, the system has been integrated into a game which focuses on their physical stimulation. The game encourages users to perform physical activities while the posture correction system helps them to adopt proper posture. The system captures limb node data received from the Kinect sensor in order to detect posture variations in real time. The DTW algorithm compares the original posture with the current one to detect any deviation from the original correct position. The system was tested and achieved a successful detection percentage of 95.20%. Experimental tests performed in a nursing home with different users show the effectiveness of the proposed solution. PMID:27196903

Ergonomic study on wrist posture when using laparoscopic tools in four different techniques regarding minimally invasive surgery.

PubMed

Bartnicka, Joanna; Zietkiewicz, Agnieszka A; Kowalski, Grzegorz J

2018-03-19

With reference to four different minimally invasive surgery (MIS) cholecystectomy the aims were: to recognize the factors influencing dominant wrist postures manifested by the surgeon; to detect risk factors involved in maintaining deviated wrist postures; to compare the wrist postures of surgeons while using laparoscopic tools. Video films were recorded during live surgeries. The films were synchronized with wrist joint angles obtained from wireless electrogoniometers placed on the surgeon's hand. The analysis was conducted for five different laparoscopic tools used during all surgical techniques. The most common wrist posture was extension. In the case of one laparoscopic tool, the mean values defining extended wrist posture were distinct in all four surgical techniques. For one type of surgical technique, considered to be the most beneficial for patients, more extreme postures were noticed regarding all laparoscopic tools. We recognized a new factor, apart from the tool's handle design, that influences extreme and deviated wrist postures. It involves three areas of task specification including the type of action, type of motion patterns and motion dynamism. The outcomes proved that the surgical technique which is most beneficial for the patient imposes the greatest strain on the surgeon's wrist.

Does increased postural threat lead to more conscious control of posture?

PubMed

Huffman, J L; Horslen, B C; Carpenter, M G; Adkin, A L

2009-11-01

Although it is well established that postural threat modifies postural control, little is known regarding the underlying mechanism(s) responsible for these changes. It is possible that changes in postural control under conditions of elevated postural threat result from a shift to a more conscious control of posture. The purpose of this study was to determine the influence of elevated postural threat on conscious control of posture and to determine the relationship between conscious control and postural control measures. Forty-eight healthy young adults stood on a force plate at two different surface heights: ground level (LOW) and 3.2-m above ground level (HIGH). Centre of pressure measures calculated in the anterior-posterior (AP) direction were mean position (AP-MP), root mean square (AP-RMS) and mean power frequency (AP-MPF). A modified state-specific version of the Movement Specific Reinvestment Scale was used to measure conscious motor processing (CMP) and movement self-consciousness (MSC). Balance confidence, fear of falling, perceived stability, and perceived and actual anxiety indicators were also collected. A significant effect of postural threat was found for movement reinvestment as participants reported more conscious control and a greater concern about their posture at the HIGH height. Significant correlations between CMP and MSC with AP-MP were observed as participants who consciously controlled and were more concerned for their posture leaned further away from the platform edge. It is possible that changes in movement reinvestment can influence specific aspects of posture (leaning) but other aspects may be immune to these changes (amplitude and frequency).

Stimulus Control, Transfer and Maintenance of Upright Walking Posture with a Severely Retarded Adult.

ERIC Educational Resources Information Center

Horner, Robert H.

Upright walking posture was successfully trained, maintained, and transferred to a new setting in a 28-year-old profoundly retarded adult. An apparatus in the S's cap and vest provided reinforcement (radio) when the S's head was up. The first four phases of the study demonstrated stimulus control in the training setting, while the next nine phases…

Postural equilibrium following exposure to weightless space flight

NASA Technical Reports Server (NTRS)

Homick, J. L.; Reschke, M. F.

1977-01-01

Postural equilibrium performance by Skylab crewmen following exposure to weightlessness of 28, 59, and 84 days respectively was evaluated using a modified version of a quantitative ataxia test developed by Graybiel and Fregly (1966). Performance for this test was measured under two sets of conditions. In the first, the crewman was required to maintain postural equilibrium on narrow metal rails (or floor) with his eyes open. In the second condition, he attempted to balance with his eyes closed. A comparison of the preflight and postflight data indicated moderate postflight decrements in postural equilibrium in three of the crewmen during the eyes open test condition. In the eyes-closed condition, a considerable decrease in ability to maintain balance on the rails was observed postflight for all crewmen tested. The magnitude of the change was most pronounced during the first postflight test day. Improvement was slow; however, on the basis of data obtained, recovery of preflight baseline levels of performance was evidently complete at the end of approximately two weeks for all crewmen. The findings are explained in terms of functional alterations in the kinesthetic, touch, vestibular and neuromuscular sensory mechanisms induced by the prolonged absence of a normal 1-G gravitational environment.

Improvement of the Chairs in Classrooms for Better Sitting Posture of Children

NASA Astrophysics Data System (ADS)

Ishihara, Keiko; Dake, Kazuo; Ishihara, Shigekazu

2010-10-01

We sought to improve the sitting postures of children studying in the classrooms of a primary school. We made the seat of a standard chair lower and attached a cushion designed by one of the authors. The cushion is cut at a 25° downward angle toward the legs to allow the users to support their weight with their feet and alleviate pressure on the underside of the thighs. We also lowered the desktop to below the height of children's elbows. Eighty-three children were given the new chairs and desks, and they were observed over 7 months. Around 10% of them voluntarily maintained good sitting postures; others straightened their postures when the teachers reminded them to do so.

The Effect of Balance Training on Postural Control in Patients with Parkinson's Disease Using a Virtual Rehabilitation System.

PubMed

Albiol-Pérez, Sergio; Gil-Gómez, José-Antonio; Muñoz-Tomás, María-Teresa; Gil-Gómez, Hermenegildo; Vial-Escolano, Raquel; Lozano-Quilis, José-Antonio

2017-03-23

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor clinical alterations among others. Postural problems have serious consequences for patients, not only limiting their daily life but also increasing some risks, like the risk of fall. Inadequate postural control and postural instability is a major problem in PD patients. A Virtual Motor Rehabilitation System (VMR) has been tested in patients with PD in the intervention period. Our purpose was to analyze the evolution of the spatial postural control during the intervention period, to see if there are any changes caused precisely by this intervention. Ten people with PD carried out 15 virtual rehabilitation sessions. We tested a groundbreaking system based on Virtual Motor Rehabilitation in two periods of time (baseline evaluation and final evaluation). In the training sessions, the participants performed a customizable treatment using a low-cost system, the Active Balance Rehabilitation system (ABAR). We stored the pressure performed by the participants every five hundredths of a second, and we analyzed the patients' pressure when they maintained their body on the left, on the right, and in the center in sitting position. Our system was able to measure postural control in every patient in each of the virtual rehabilitation sessions. There are no significant differences in the performance of postural control in any of the positions evaluated throughout the sessions. Moreover, the results show a trend to an improvement in all positions. This improvement is especially remarkable in the left/right positions, which are the most important positions in order to avoid problems such as the risk of fall. With regard to the suitability of the ABAR system, we have found outstanding results in enjoyment, success, clarity, and helpfulness. Although PD is a progressive neurodegenerative disorder, the results demonstrate that patients with PD maintain or even improve their postural control in all positions. We think that the main factor influencing these results is that patients use more of their available cognitive processing to improve their postural control. The ABAR system allows us to make this assumption because the system requires the continuous attention of patients, promoting cognitive processing.

Effect of Sitting Pause Times on Balance After Supine to Standing Transfer in Dim Light.

PubMed

Johnson, Eric G; Albalwi, Abdulaziz A; Al-Dabbak, Fuad M; Daher, Noha S

2017-06-01

The risk of falling for older adults increases in dimly lit environments. Longer sitting pause times, before getting out of bed and standing during the night, may improve postural stability. The purpose of this study was to measure the effect of sitting pause times on postural sway velocity immediately after a supine to standing transfer in a dimly lit room in older adult women. Eighteen healthy women aged 65 to 75 years who were able to independently perform supine to standing transfers participated in the study. On each of 2 consecutive days, participants assumed the supine position on a mat table and closed their eyes for 45 minutes. Then, participants were instructed to open their eyes and transfer from supine to sitting, with either 2- or 30-second pause in the sitting position followed by standing. The sitting pause time order was randomized. A significant difference was observed in postural sway velocity between the 2- and 30-second sitting pause times. The results revealed that there was less postural sway velocity after 30-second than 2-second sitting pause time (0.61 ± 0.19 vs 1.22 ± 0.68, P < .001). Falls related to bathroom usage at night are the most common reported falls among older adults. In the present study, the investigators studied the effect of sitting pause times on postural sway velocity after changing position from supine to standing in a dimly lit environment. The findings showed that the mean postural sway velocity was significantly less after 30-second sitting pause time compared with 2-second sitting pause time. Postural sway velocity decreased when participants performed a sitting pause of 30 seconds before standing in a dimly lit environment. These results suggest that longer sitting pause times may improve adaptability to dimly lit environments, contributing to improved postural stability and reduced risk of fall in older adult women when getting out of bed at night.

A balance and proprioception intervention programme to enhance combat performance in military personnel.

PubMed

Funk, Shany; Jacob, T; Ben-Dov, D; Yanovich, E; Tirosh, O; Steinberg, N

2018-02-01

Optimal functioning of the lower extremities under repeated movements on unstable surfaces is essential for military effectiveness. Intervention training to promote proprioceptive ability should be considered in order to limit the risk for musculoskeletal injuries. The aim of this study was to assess the effect of a proprioceptive intervention programme on static and dynamic postural balance among Israel Defense Forces combat soldiers. Twenty-seven male soldiers, aged 18-20 years, from a physical fitness instructor's course, were randomly divided into two groups matched by age and army unit. The intervention group (INT) underwent 4 weeks of proprioceptive exercises for 10 min daily; the control group underwent 4 weeks of upper body stretching exercises for 10 min daily. All participants were tested pre and postintervention for both static and dynamic postural balance. Significant interaction (condition*pre-post-test*group) was found for static postural balance, indicating that for the INT group, in condition 3 (on an unstable surface-BOSU), the post-test result was significantly better compared with the pretest result (p<0.05). Following intervention, the INT group showed significant correlations between static postural stability in condition 2 (eyes closed) and the dynamic postural stability (length of time walked on the beam following fatigue) ( r ranged from 0.647 to 0.822; p<0.05). The proprioceptive intervention programme for combat soldiers improved static postural balance on unstable surfaces, and improved the correlation between static postural balance in the eyes closed condition and dynamic postural balance following fatigue. Further longitudinal studies are needed to verify the relationship between proprioception programmes, additional weight bearing and the reduction of subsequent injuries in combat soldiers. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Anticipatory postural adjustments and focal performance during bilateral forward-reach task under different stance conditions.

PubMed

Yiou, Eric; Mezaour, Malha; Le Bozec, Serge

2009-04-01

This study investigated how young healthy subjects control their equilibrium in situations of instability specifically elicited by a reduced capacity of force production in the postural muscle system. Ten subjects displaced a bar forward with both hands at maximal velocity toward a target while standing on the dominant leg (UNID), on the nondominant leg (UNIND), or on both legs. In each stance condition, anticipatory postural adjustments (APAs) were elicited. Along the anteroposterior axis, APAs were two-times longer in UNID and UNIND than in bipedal stance, while the anticipatory inertia forces remained equivalent. The focal performance was maintained without any additive postural perturbation. A small effect of leg dominance could be detected on APAs along the mediolateral axis (i.e., anticipatory inertia forces were higher in UNIND than in UNID). These results stress the adaptability of the central nervous system to the instability specifically elicited by reduced postural muscle system efficiency.

Effect of mat pilates exercise on postural alignment and body composition of middle-aged women.

PubMed

Lee, Hyo Taek; Oh, Hyun Ok; Han, Hui Seung; Jin, Kwang Youn; Roh, Hyo Lyun

2016-06-01

[Purpose] This study attempted to examine whether Pilates is an effective exercise for improving the postural alignment and health of middle-aged women. [Subjects and Methods] The participants in this study were 36 middle-aged women (20 in the experimental group, 16 in the control group). The experimental group participated in Pilates exercise sessions three times a week for 12 weeks. Body alignment and composition measurements before and after applying the Pilates exercise program were performed with a body composition analyzer and a three-dimensional scanner. [Results] Postural alignment in the sagittal and horizontal planes was enhanced in the Pilates exercise group. Trunk alignment showed correlations with body fat and muscle mass. [Conclusion] The Pilates exercises are performed symmetrically and strengthen the deep muscles. Moreover, the results showed that muscle mass was correlated with trunk postural alignment and that the proper amount of muscle is critical in maintaining trunk postural alignment.

M.I.T./Canadian vestibular experiments on the Spacelab-1 mission. V - Postural responses following exposure to weightlessness

NASA Technical Reports Server (NTRS)

Kenyon, R. V.; Young, L. R.

1986-01-01

The four science crewmembers of Spacelab-1 were tested for postural control before and after a 10 day mission in weightlessness. Previous reports have shown changes in astronaut postural behavior following a return to earth's 1-g field. This study was designed to identify changes in EMG latency and amplitudes that might explain the instabilities observed post-flight. Erect posture was tested having the subject stand on a pneumatically driven posture platform which pitched rapidly and unexpectedly about the ankles causing dorsi- and plantarflexion. Electromyographic (EMG) activity from the tibialis anterior and the gastrocnemius-soleus muscles was measured during eyes open and eyes closed trials. The early (pre 500 ms) EMG response characteristics (latency, amplitude) in response to a disturbance in the posture of the subject were apparently unchanged by the 10 days of weightlessness. However, the late (post 500 ms) response showed higher amplitudes than was found pre-flight. General postural control was quantitatively measured pre- and post-flight by a 'sharpened Romberg Rails test'. This test showed decrements in standing stability with eyes closed for several days post-flight.

Exemplification of Movement Patterns and Their Influence on Body Posture in Younger School-Age Children on the Basis of an Authorial Program “I Take Care of My Spine”

PubMed Central

Brzek, Anna; Plinta, Ryszard

2016-01-01

Abstract Exemplification of movement patterns is most noticeable in the youngest pupils group. Generally, children do not know which patterns are correct and which ones are risk factors. After correcting and stabilizing some improper patterns, a child can perform their daily activities without constant cognizance of their appropriateness. The concept of this research is included in a paradigm for the quality research conducted as action-research, which assumed a quality and efficiency improvement of health education in Polish schools. The main aim of this study was to encourage pupils, their parents and teachers to perform pro-health behaviors oriented toward maintaining an appropriate body posture. First, the study aimed to assess the postures of children involved in the authorial program “I take care of my spine” in comparison with a group of children without diagnosed postural defects and not involved in the curriculum. The examinations covered a group of 144 children (group A) ages 7 to 9 years (mean 7.60 ± 0.64 years) with appropriate body postures recognized in the screening test, which was conducted at a school where the curriculum “I take care of my spine” was launched. The control group included 222 healthy children at a similar age who attended schools where the curriculum was not implemented. The examinations were performed 2 times, as follows: the first time occurred before the program “I take care of my spine” was launched (initial examination), and the second time after 9 to 10 months of full participation in the program's activities and after 1 year of observation of children from group B (final examination). A significant improvement of posturometric parameters in the main group and worsening of the parameters in the control group were noted. The results in examined groups of children and diversification of the results were linked to implementing the prevention program in the main group. In the group of children involved in the postural prevention program, the weight of school bags was significantly reduced. This objective was particularly important for students because the manner of movement pattern exemplification will influence children's lives in the future, and in a wider perspective, it will play a crucial role in assessing their quality of life as adults. PMID:27015165

Exemplification of Movement Patterns and Their Influence on Body Posture in Younger School-Age Children on the Basis of an Authorial Program "I Take Care of My Spine".

PubMed

Brzek, Anna; Plinta, Ryszard

2016-03-01

Exemplification of movement patterns is most noticeable in the youngest pupils group. Generally, children do not know which patterns are correct and which ones are risk factors. After correcting and stabilizing some improper patterns, a child can perform their daily activities without constant cognizance of their appropriateness. The concept of this research is included in a paradigm for the quality research conducted as action-research, which assumed a quality and efficiency improvement of health education in Polish schools.The main aim of this study was to encourage pupils, their parents and teachers to perform pro-health behaviors oriented toward maintaining an appropriate body posture. First, the study aimed to assess the postures of children involved in the authorial program "I take care of my spine" in comparison with a group of children without diagnosed postural defects and not involved in the curriculum.The examinations covered a group of 144 children (group A) ages 7 to 9 years (mean 7.60 ± 0.64 years) with appropriate body postures recognized in the screening test, which was conducted at a school where the curriculum "I take care of my spine" was launched. The control group included 222 healthy children at a similar age who attended schools where the curriculum was not implemented. The examinations were performed 2 times, as follows: the first time occurred before the program "I take care of my spine" was launched (initial examination), and the second time after 9 to 10 months of full participation in the program's activities and after 1 year of observation of children from group B (final examination).A significant improvement of posturometric parameters in the main group and worsening of the parameters in the control group were noted. The results in examined groups of children and diversification of the results were linked to implementing the prevention program in the main group. In the group of children involved in the postural prevention program, the weight of school bags was significantly reduced.This objective was particularly important for students because the manner of movement pattern exemplification will influence children's lives in the future, and in a wider perspective, it will play a crucial role in assessing their quality of life as adults.

Time to Stabilization of Anterior Cruciate Ligament–Reconstructed Versus Healthy Knees in National Collegiate Athletic Association Division I Female Athletes

PubMed Central

Webster, Kathryn A.; Gribble, Phillip A.

2010-01-01

Abstract Context: Jump landing is a common activity in collegiate activities, such as women's basketball, volleyball, and soccer, and is a common mechanism for anterior cruciate ligament (ACL) injury. It is important to better understand how athletes returning to competition after ACL reconstruction are able to maintain dynamic postural control during a jump landing. Objective: To use time to stabilization (TTS) to measure differences in dynamic postural control during jump landing in ACL-reconstructed (ACLR) knees compared with healthy knees among National Collegiate Athletic Association Division I female athletes. Design: Case-control study. Setting: University athletic training research laboratory. Patients or Other Participants: Twenty-four Division I female basketball, volleyball, and soccer players volunteered and were assigned to the healthy control group (n  =  12) or the ACLR knee group (n  =  12). Participants with ACLR knees were matched to participants with healthy knees by sport and by similar age, height, and mass. Intervention(s): At 1 session, participants performed a single-leg landing task for both limbs. They were instructed to stabilize as quickly as possible in a single-limb stance and remain as motionless as possible for 10 seconds. Main Outcome Measure(s): The anterior-posterior TTS and medial-lateral TTS ground reaction force data were used to calculate resultant vector of the TTS (RVTTS) during a jump landing. A 1-way analysis of variance was used to determine group differences on RVTTS. The means and SDs from the participants' 10 trials in each leg were used for the analyses. Results: The ACLR group (2.01 ± 0.15 seconds, 95% confidence interval [CI]  =  1.91, 2.10) took longer to stabilize than the control group (1.90 ± 0.07 seconds, 95% CI  =  1.86, 1.95) (F1,22  =  4.28, P  =  .05). This result was associated with a large effect size and a 95% CI that did not cross zero (Cohen d  =  1.0, 95% CI  =  0.91, 1.09). Conclusions: Although they were Division I female athletes at an average of 2.5 years after ACL reconstruction, participants with ACLR knees demonstrated dynamic postural-control deficits as evidenced by their difficulty in controlling ground reaction forces. This increased TTS measurement might contribute to the established literature reflecting differences in single-limb dynamic control. Clinicians might need to focus rehabilitation efforts on stabilization after jump landing. Further research is needed to determine if TTS is a contributing factor in future injury. PMID:21062181

Virtual reality applications in improving postural control and minimizing falls.

PubMed

Virk, Sumandeep; McConville, Kristiina M Valter

2006-01-01

Maintaining balance under all conditions is an absolute requirement for humans. Orientation in space and balance maintenance requires inputs from the vestibular, the visual, the proprioceptive and the somatosensory systems. All the cues coming from these systems are integrated by the central nervous system (CNS) to employ different strategies for orientation and balance. How the CNS integrates all the inputs and makes cognitive decisions about balance strategies has been an area of interest for biomedical engineers for a long time. More interesting is the fact that in the absence of one or more cues, or when the input from one of the sensors is skewed, the CNS "adapts" to the new environment and gives less weight to the conflicting inputs [1]. The focus of this paper is a review of different strategies and models put forward by researchers to explain the integration of these sensory cues. Also, the paper compares the different approaches used by young and old adults in maintaining balance. Since with age the musculoskeletal, visual and vestibular system deteriorates, the older subjects have to compensate for these impaired sensory cues for postural stability. The paper also discusses the applications of virtual reality in rehabilitation programs not only for balance in the elderly but also in occupational falls. Virtual reality has profound applications in the field of balance rehabilitation and training because of its relatively low cost. Studies will be conducted to evaluate the effectiveness of virtual reality training in modifying the head and eye movement strategies, and determine the role of these responses in the maintenance of balance.

The effects of whole body vibration combined biofeedback postural control training on the balance ability and gait ability in stroke patients.

PubMed

Uhm, Yo-Han; Yang, Dae-Jung

2017-11-01

[Purpose] The purpose of this study was to examine the effect of biofeedback postural control training using whole body vibration in acute stroke patients on balance and gait ability. [Subjects and Methods] Thirty stroke patients participated in this study and were divided into a group of 10, a group for biofeedback postural control training combined with a whole body vibration, one for biofeedback postural control training combined with an aero-step, and one for biofeedback postural control training. Biorescue was used to measure the limits of stability, balance ability, and Lukotronic was used to measure step length, gait ability. [Results] In the comparison of balance ability and gait ability between the groups for before and after intervention, Group I showed a significant difference in balance ability and gait ability compared to Groups II and III. [Conclusion] This study showed that biofeedback postural control training using whole body vibration is effective for improving balance ability and gait ability in stroke patients.

Delayed Compensatory Postural Adjustments After Lateral Perturbations Contribute to the Reduced Ability of Older Adults to Control Body Balance.

PubMed

Claudino, Renato; Dos Santos, Marcio José; Mazo, Giovana Zarpellon

2017-10-01

The goal of this study was to investigate the timing of compensatory postural adjustments in older adults during body perturbations in the mediolateral direction, circumstances that increase their risk of falls. The latencies of leg and trunk muscle activation to body perturbations at the shoulder level and variables of center of pressure excursion, which characterize postural stability, were analyzed in 40 older adults (nonfallers and fallers evenly split) and in 20 young participants. The older adults exhibited longer latencies of muscular activation in eight out of 15 postural muscles as compared with young participants; for three muscles, the latencies were longer for the older fallers than nonfallers. Simultaneously, the time for the center of pressure displacement reached its peak after the perturbation was significant longer in both groups of older adults. The observed delays in compensatory postural adjustments may affect the older adults' ability to prompt control body balance after postural disturbances and predispose them to falls.

Both anticipatory and compensatory postural adjustments are adapted while catching a ball in unstable standing posture.

PubMed

Scariot, Vanessa; Rios, Jaqueline L; Claudino, Renato; Dos Santos, Eloá C; Angulski, Hanna B B; Dos Santos, Marcio J

2016-01-01

The main objective of this study was to analyze the role of balance exercises on anticipatory (APA) and compensatory (CPA) postural adjustments in different conditions of postural stability. Sixteen subjects were required to catch a ball while standing on rigid floor, trampoline and foam cushion surfaces. Electromyographic activities (EMG) of postural muscles were analyzed during time windows typical for APAs and CPAs. Overall there were a reciprocal activation of the muscles around the ankle and co-activations between ventral and dorsal muscles of the thigh and trunk during the catching a ball task. Compared to the rigid floor, the tibialis anterior activation was greater during the trampoline condition (CPA: p = 0.006) and the soleus muscle inhibition was higher during foam cushion condition (APA: p = 0.001; CPA: p = 0.007). Thigh and trunk muscle activities were similar across the conditions. These results advance the knowledge in postural control during body perturbations standing on unstable surfaces. Published by Elsevier Ltd.

Evaluation of the lambda model for human postural control during ankle strategy.

PubMed

Micheau, Philippe; Kron, Aymeric; Bourassa, Paul

2003-09-01

An accurate modeling of human stance might be helpful in assessing postural deficit. The objective of this article is to validate a mathematical postural control model for quiet standing posture. The postural dynamics is modeled in the sagittal plane as an inverted pendulum with torque applied at the ankle joint. The torque control system is represented by the physiological lambda model. Two neurophysiological command variables of the central nervous system, designated lambda and micro, establish the dynamic threshold muscle at which motoneuron recruitment begins. Kinematic data and electromyographic signals were collected on four young males in order to measure small voluntary sway and quiet standing posture. Validation of the mathematical model was achieved through comparison of the experimental and simulated results. The mathematical model allows computation of the unmeasurable neurophysiological commands lambda and micro that control the equilibrium position and stability. Furthermore, with the model it is possible to conclude that low-amplitude body sway during quiet stance is commanded by the central nervous system.

Postural control in restless legs syndrome with medication intervention using pramipexole.

PubMed

Ahlgrén-Rimpiläinen, Aulikki; Lauerma, Hannu; Kähkönen, Seppo; Aalto, Heikki; Tuisku, Katinka; Holi, Matti; Pyykkö, Ilmari; Rimpiläinen, Ilpo

2014-02-01

Central dopamine regulation is involved in postural control and in the pathophysiology of restless legs syndrome (RLS) and Parkinson's disease (PD). Postural control abnormalities have been detected in PD, but there are no earlier studies with regard to RLS and postural control. Computerized force platform posturography was applied to measure the shift and the velocity (CPFV) of center point of forces (CPF) with eyes open (EO) and eyes closed (EC) in controls (n = 12) and prior and after a single day intervention with pramipexole in RLS subjects (n = 12). CPFV (EO) was significantly lower in the RLS group (p < 0.05) than in controls. After pramipexole intake, the difference disappeared and the subjective symptom severity diminished. Pramipexole did not significantly influence CPFV (EC) or CPF shift direction. Subjects with RLS used extensively visual mechanisms to control vestibule-spinal reflexes to improve or compensate the postural stability. Further research is needed to clarify altered feedback in the central nervous system and involvement of dopamine and vision in the postural control in RLS.

Between-day reliability of time-to-contact measures used to assess postural stability.

PubMed

Wheat, Jonathan S; Haddad, Jeffrey M; Scaife, Robert

2012-02-01

Traditional measures of postural stability consider movement of the center of pressure (COP) or the center of mass (COM) without regard to the boundary of support (BOS). A potentially more appropriate measure is postural time-to-contact (TtC) which defines the spatio-temporal proximity of the COM or COP to the BOS. Given the increasing popularity of TtC measures, it is important to determine their reliability. Therefore, the purpose of this study was to determine the effects of the number of trials and trial duration on the reliability of postural TtC measures. COP data were collected (100 Hz) in 16 young healthy participants during 10 trials (60-s duration) of quiet standing with eyes open on two occasions - seven days apart. Postural TtC of each trial was calculated using two different methods. The intersession reliability of the TtC measures was assessed by calculating between session intraclass correlation coefficients (ICC(2,1)) using different combinations of the number of trials (1-10) and trial duration (10, 20, 30, 40, 50 and 60s). Both TtC methods were very reliable. Additionally, both measures of TtC were more reliable than the standard deviation of the anterior-posterior COP and slightly more reliable than path length. This difference was most pronounced when fewer and shorter trials were used. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of cognitive and motor tasks on postural stability in Parkinson's disease: a posturographic study.

PubMed

Marchese, Roberta; Bove, Marco; Abbruzzese, Giovanni

2003-06-01

To analyse the effect of concomitant cognitive or motor task performance on balance control in Parkinson's disease (PD), we performed a posturographic study in 24 PD patients and in 20 sex- and age-matched control subjects. Postural sway was measured with eyes open (EO) and eyes closed (EC) during quiet stance and during performance of calculation or motor sequence of thumb opposition to the other fingers. No difference of centre of foot pressure (COP) parameters was observed during quiet standing (either EO or EC) between patients and controls, but visual deprivation induced in both groups a worsening of postural stability. COP area was significantly increased in PD patients during dual task performance, whereas no difference of COP path and x-y axes was observed. The effects induced by the performance of cognitive or motor task were significantly more evident in PD patients with clinical evidence of postural instability (presence of prior falls in the history). This study demonstrates that dual task interference on postural control can be observed in PD patients during performance of cognitive as well as motor tasks. The balance deterioration during dual task performance was significantly enhanced in patients with history of prior falls. These findings have some implications for the strategies to be used in reducing the risk of fall in PD. Copyright 2003 Movement Disorder Society

A Wireless Accelerometer-Based Body Posture Stability Detection System and Its Application for Meditation Practitioners

PubMed Central

Chang, Kang-Ming; Chen, Sih-Huei; Lee, Hsin-Yi; Ching, Congo Tak-Shing; Huang, Chun-Lung

2012-01-01

The practice of meditation has become an interesting research issue in recent decades. Meditation is known to be beneficial for health improvement and illness reduction and many studies on meditation have been made, from both the physiological and psychological points of view. It is a fundamental requirement of meditation practice to be able to sit without body motion. In this study, a novel body motion monitoring and estimation system has been developed. A wireless tri-axis accelerometer is used to measure body motion. Both a mean and maximum motion index is derived from the square summation of three axes. Two experiments were conducted in this study. The first experiment was to investigate the motion index baseline among three leg-crossing postures. The second experiment was to observe posture dynamics for thirty minute’s meditation. Twenty-six subjects participated in the experiments. In one experiment, thirteen subjects were recruited from an experienced meditation group (meditation experience > 3 years); and the other thirteen subjects were beginners (meditation experience < 1 years). There was a significant posture stability difference between both groups in terms of either mean or maximum parameters (p < 0.05), according to the results of the experiment. Results from another experiment showed that the motion index is different for various postures, such as full-lotus < half-lotus < non-lotus. PMID:23250281

The change of sleeping and lying posture of Japanese black cows after moving into new environment.

PubMed

Fukasawa, Michiru; Komatsu, Tokushi; Higashiyama, Yumi

2018-04-25

The environmental change is one of the stressful events in livestock production. Change in environment disturbed cow behavior and cows needed several days to reach stable behavioral pattern, especially sleeping posture (SP) and lying posture (LP) have been used as an indicator for relax and well-acclimated to its environment. The aim of this study examines how long does Japanese black cow required for stabilization of SP and LP after moving into new environment. Seven pregnant Japanese black cows were used. Cows were moved into new tie-stall shed and measured sleeping and lying posture 17 times during 35 experimental days. Both SP and LP were detected by accelerometer fixed on middle occipital and hip-cross, respectively. Daily total time, frequency, and average bout of both SP and LP were calculated. Daily SP time was the shortest on day 1, and increased to the highest on day3. It decreased until day 9, after that stabilized about 65 min /day till the end of experiment. The longest average SP bout was shown on day 1, and it decreased to stabilize till day 7. Daily LP time was changed as same manner as daily SP time. The average SP bout showed the longest on day 1, and it decreased to stable level till day 7. On the other hand, the average LP bout showed the shortest on day1, and it was increased to stable level till on day 7. These results showed that pregnant Japanese black cows needed 1 week to stabilize their SP. However, there were different change pattern between the average SP and LP bout, even though the change pattern of daily SP and LP time were similar.

No beneficial effects of vitamin D supplementation on muscle function or quality of life in primary hyperparathyroidism: results from a randomized controlled trial.

PubMed

Rolighed, Lars; Rejnmark, Lars; Sikjaer, Tanja; Heickendorff, Lene; Vestergaard, Peter; Mosekilde, Leif; Christiansen, Peer

2015-05-01

Impairments of muscle function and strength in patients with primary hyperparathyroidism (PHPT) are rarely addressed, although decreased muscle function may contribute to increased fracture risk. We aimed to assess the changes in muscle strength, muscle function, postural stability, quality of life (QoL), and well-being during treatment with vitamin D or placebo before and after parathyroidectomy (PTX) in PHPT patients. A randomized placebo-controlled trial. We included 46 PHPT patients, mean age 58 (range 29-77) years and 35 (76%) were women. Daily treatment with 70 μg (2800 IU) cholecalciferol or placebo for 52 weeks. Treatment was administered 26 weeks before PTX and continued for 26 weeks after PTX. Changes in QoL and measures of muscle strength and function. Preoperatively, 25-hydroxyvitamin D (25OHD) increased significantly (50-94 nmol/l) compared with placebo (57-52 nmol/l). We did not measure any beneficial effects of supplementation with vitamin D compared with placebo regarding well-being, QoL, postural stability, muscle strength, or function. In all patients, we measured marked improvements in QoL, well-being (P<0.01), muscle strength in the knee flexion and extension (P<0.001), and muscle function tests (P<0.01) after surgical cure. Postural stability improved during standing with eyes closed (P<0.05), but decreased with eyes open (P<0.05). Patients with PHPT and 25OHD levels around 50 nmol/l did not benefit from vitamin D supplementation concerning muscle strength, muscle function, postural stability, well-being, or QoL. Independent of preoperative 25OHD levels, PTX improved these parameters. © 2015 European Society of Endocrinology.

Pharmacodynamic and pharmacokinetic effects of MK-0343, a GABA(A) alpha2,3 subtype selective agonist, compared to lorazepam and placebo in healthy male volunteers.

PubMed

de Haas, S L; de Visser, S J; van der Post, J P; Schoemaker, R C; van Dyck, K; Murphy, M G; de Smet, M; Vessey, L K; Ramakrishnan, R; Xue, L; Cohen, A F; van Gerven, J M A

2008-01-01

The use of non-selective gamma-aminobutyric acid (GABA) enhancers, such as benzodiazepines in the treatment of anxiety disorders is still widespread but hampered by unfavourable side effects. some of these may be associated with binding properties to certain subtypes of the GABA(A) receptor that are unnecessary for therapeutic effects. MK-0343 was designed to be a less sedating anxiolytic, based on reduced efficacy at the alpha1 subtype and significant efficacy at alpha2 and alpha3 subtypes of the GABA(A) receptor. This paper is a double-blind, four-way cross-over (n = 12) study to investigate the effects of MK-0343 (0.25 and 0.75 mg) in comparison to placebo and an anxiolytic dose (2 mg) of the non-selective agonist lorazepam. Effects were measured by eye movements, body sway, Visual Analogue scales (VAS) and memory tests. Lorazepam impaired saccadic peak velocity (SPV), VAs alertness scores, postural stability and memory and increased saccadic latency and inaccuracy. MK-0343 0.75 mg was equipotent with lorazepam as indicated by SPV (-42.4 deg/s), saccadic latency (0.02 s) and VAS alertness scores (1.50 ln mm), while effects on memory and postural stability were smaller. MK-0343 0.25 mg only affected postural stability to a similar extent as MK-0343 0.75 mg. The effect profile of MK-0343 0.75 mg is different from the full agonist lorazepam, which could reflect the selective actions of this compound. Although less effect on VAS alertness was expected, diminished effects on memory and postural stability were present. Clinical studies in anxiety patients should show whether this dose of MK-0343 is therapeutically effective with a different side-effect profile.

Do children perceive postural constraints when estimating reach or action planning?

PubMed

Gabbard, Carl; Cordova, Alberto; Lee, Sunghan

2009-03-01

Estimation of whether an object is reachable from a specific body position constitutes an important aspect in effective motor planning. Researchers who estimate reachability by way of motor imagery with adults consistently report the tendency to overestimate, with some evidence of a postural effect (postural stability hypothesis). This idea suggests that perceived reaching limits depend on an individual's perceived postural constraints. Based on previous work with adults, the authors expected a significant postural effect with the Reach 2 condition, as evidenced by reduced overestimation. Furthermore, the authors hypothesized that the postural effect would be greater in younger children. They then tested these propositions among children aged 7, 9, and 11 years by asking them to estimate reach while seated (Reach 1) and in the more demanding posture of standing on 1 foot and leaning forward (Reach 2). Results indicated no age or condition difference, therefore providing no support for a postural effect. When the authors compared these data to a published report of adults, a developmental difference emerged. That is, adults recognize the perceived postural constraint of the standing position resulting in under- rather than overestimation, as displayed in the seated condition. Although preliminary, these observations suggest that estimates of reach (action planning) continue to be refined between late childhood and young adulthood.

Inefficient postural responses to unexpected slips during walking in older adults.

PubMed

Tang, P F; Woollacott, M H

1998-11-01

Slips account for a high percentage of falls and subsequent injuries in community-dwelling older adults but not in young adults. This phenomenon suggests that although active and healthy older adults preserve a mobility level comparable to that of young adults, these older adults may have difficulty generating efficient reactive postural responses when they slip. This study tested the hypothesis that active and healthy older adults use a less effective reactive balance strategy than young adults when experiencing an unexpected forward slip occurring at heel strike during walking. This less effective balance strategy would be manifested by slower and smaller postural responses, altered temporal and spatial organization of the postural responses, and greater upper trunk instability after the slip. Thirty-three young adults (age range=19-34 yrs, mean=25+/-4 yrs) and 32 community-dwelling older adults (age range=70-87 yrs, mean=74+/-14 yrs) participated. Subjects walked across a movable forceplate which simulated a forward slip at heel strike. Surface electromyography was recorded from bilateral leg, thigh, hip, and trunk muscles. Kinematic data were collected from the right (perturbed) side of the body. Although the predominant postural muscles and the activation sequence of these muscles were similar between the two age groups, the postural responses of older adults were of longer onset latencies, smaller magnitudes, and longer burst durations compared to young adults. Older adults also showed a longer coactivation duration for the ankle, knee, and trunk agonist/antagonist pairs on the perturbed side and for the knee agonist/antagonist pair on the nonperturbed side. Behaviorally, older adults became less stable after the slips. This was manifested by a higher incidence of being tripped (21 trials in older vs 5 trials in young adults) and a greater trunk hyperextension with respect to young adults. Large arm elevation was frequently used by older adults to assist in maintaining trunk stability. In an attempt to quickly reestablish the base of support after the slips, older adults had an earlier contralateral foot strike and shortened stride length. The combination of slower onset and smaller magnitude of postural responses to slips in older adults resulted in an inefficient balance strategy. Older adults needed secondary compensatory adjustments, including a lengthened response duration and the use of the arms, to fully regain balance and prevent a fall. The shorter stride length and earlier contralateral foot strike following the slip indicate use of a more conservative balance strategy in older adults.

Comparison of Postural Recovery Following Short and Long Duration Spaceflights

NASA Technical Reports Server (NTRS)

Wood, S. J.; Fiedler, J.; Taylor, L. C.; Kozlovskaya, I.; Black, F. O.; Paloski, W. H.

2010-01-01

INTRODUCTION: Post-flight postural ataxia reflects adaptive changes to vestibulo-spinal reflexes and control strategies adopted for movement in weightlessness. Quantitative measures obtained during computerized dynamic posturography (CDP) from US and Russian programs provide insight into the effect of spaceflight duration in terms of both the initial decrements and recovery of postural stability. METHODS: CDP was obtained on 117 crewmembers following Shuttle flights lasting 4-17 days, and on 64 crewmembers following long-duration missions lasting 48-380 days. Although the number and timing of sessions varied, the goal was to characterize postural recovery pooling similar measures from different research and flight medicine programs. This report focuses on eyes closed, head erect conditions with either a fixed or sway-referenced base of support. A smaller subset of subjects repeated the sway-referenced condition while making pitch head movements (+/- 20deg at 0.33Hz). Equilibrium scores were derived from peak-to-peak anterior-posterior sway. Fall probability was modeled using Bayesian statistical methods to estimate parameters of a logit function. RESULTS: The standard Romberg condition was the least sensitive. Longer duration flights led to larger decrements in stability with sway-reference support during the first 1-2 days, although the timecourse of recovery was similar across flight duration with head erect. Head movements led to increased incidence of falls during the first week, with a significantly longer recovery following long duration flights. CONCLUSIONS: The diagnostic assessment of postural instability, and differences in the timecourse of postural recovery between short and long flight durations, are more pronounced during unstable support conditions requiring active head movements.

Comprehensive Group Therapy of Obesity and Its Impact on Selected Anthropometric and Postural Parameters.

PubMed

Horák, Stanislav; Sovová, Eliška; Pastucha, Dalibor; Konečný, Petr; Radová, Lenka; Calabová, Naděžda; Janoutová, Jana; Janout, Vladimír

2017-12-01

Obesity is a multifactorial disease. This non-infectious epidemic has reached pandemic proportions in the 21 century. Posture is a dynamic process referring to an active maintenance of body movement segments against the action of external forces. The aim of the study was to investigate the effect of comprehensive group therapy for obese persons on selected anthropometric and postural parameters. The study comprised 53 females with a mean age of 44.5 years (range 29–65 years, standard deviation 9.42 years, median 44 years), who completed a controlled weight loss programme. At the beginning and at the end of the programme, anthropometric parameters (Body Mass Index (BMI), weight and waist circumference) were measured and the posturography tests Limits of Stability (LOS) and Motor Control Test (MCT) were performed using the NeuroCom's SMART EquiTest system. The data were statistically analyzed using R software at a level of significance of 0.05. There were positive changes after the controlled weight loss programme in anthropometric parameters (BMI reduction, with p<0.001; waist circumference reduction, with p<0.001; and weight loss, with p<0.001), postural stability with statistically significant (p<0.05) improvements in both postural activity (LOS test parameters) and reactions (MCT parameters). The study showed a statistically significant effect of comprehensive group therapy for obesity in terms of reductions in waist circumference, body weight and BMI, and thus the overall reduction of both cardiovascular and metabolic risks, as well as improved postural skills (activity and reactions). Copyright© by the National Institute of Public Health, Prague 2017

Recalibrating disparities in perceived and actual balance abilities in older adults: a mixed-methods evaluation of a novel exergaming intervention.

PubMed

Ellmers, Toby J; Paraskevopoulos, Ioannis Th; Williams, A Mark; Young, William R

2018-03-22

Published reports suggest a disparity between perceived and actual balance abilities, a trait associated with increased fall-risk in older adults. We investigate whether it is possible to 'recalibrate' these disparities using a novel gaming intervention. We recruited 26 older adults for a 4-week intervention in which they participated in 8-sessions using a novel gaming intervention designed to provide explicit, augmented feedback related to postural control. Measures of perceived balance abilities (Falls Efficacy Scale-International) and actual postural control (limits of stability) were assessed pre- and post-intervention. We used focus groups to elicit the opinions of participants about how the game may have influenced balance abilities and confidence. A stronger alignment was observed between postural control and perceived balance capabilities post-intervention (i.e., significant correlations between Falls Efficacy Scale-International scores and limits of stability which were not present pre-intervention). Also, significant improvements in measures of postural control were observed, with these improvements confined to the aspects of postural control for which the exergame provided explicit, augmented feedback. Qualitative data revealed that the intervention made participants more "aware" of their balance abilities. Our results demonstrate that it is possible to recalibrate the perceptions of older adults relating to their balance abilities through a targeted, short-term intervention. We propose that the post-intervention improvements in postural control may have been, in part, the result of this recalibration; with altered perceptions leading to changes in balance performance. Findings support the application of novel interventions aimed at addressing the psychological factors associated with elderly falls.

Stability and Control of Human Trunk Movement During Walking.

PubMed

Wu, Q.; Sepehri, N.; Thornton-Trump, A. B.; Alexander, M.

1998-01-01

A mathematical model has been developed to study the control mechanisms of human trunk movement during walking. The trunk is modeled as a base-excited inverted pendulum with two-degrees of rotational freedom. The base point, corresponding to the bony landmark of the sacrum, can move in three-dimensional space in a general way. Since the stability of upright posture is essential for human walking, a controller has been designed such that the stability of the pendulum about the upright position is guaranteed. The control laws are developed based on Lyapunov's stability theory and include feedforward and linear feedback components. It is found that the feedforward component plays a critical role in keeping postural stability, and the linear feedback component, (resulting from viscoelastic function of the musculoskeletal system) can effectively duplicate the pattern of trunk movement. The mathematical model is validated by comparing the simulation results with those based on gait measurements performed in the Biomechanics Laboratory at the University of Manitoba.

Foam pad of appropriate thickness can improve diagnostic value of foam posturography in detecting postural instability.

PubMed

Liu, Bo; Leng, Yangming; Zhou, Renhong; Liu, Jingjing; Liu, Dongdong; Liu, Jia; Zhang, Su-Lin; Kong, Wei-Jia

2018-04-01

The present study investigated the effect of foam thickness on postural stability in patients with unilateral vestibular hypofunction (UVH) during foam posturography. Static and foam posturography were performed in 33 patients (UVH group) and 30 healthy subjects (control group) with eyes open (EO) and closed (EC) on firm surface and on 1-5 foam pad(s). Sway velocity (SV) of center of pressure, standing time before falling (STBF) and falls reaction were recorded and analyzed. (1) SVs had an increasing tendency in both groups as the foam pads were added under EO and EC conditions. (2) STBFs, only in UVH group with EC, decreased with foam thickness increasing. (3) Significant differences in SV were found between the control and UVH group with EO (except for standing on firm surface, on 1 and 2 foam pad(s)) and with EC (all surface conditions). (4) Receiver operating characteristic curve analysis showed that the SV could better reflect the difference in postural stability between the two groups while standing on the 4 foam pads with EC. Our study showed that diagnostic value of foam posturography in detecting postural instability might be enhanced by using foam pad of right thickness.

Minimalist, standard and no footwear on static and dynamic postural stability following jump landing.

PubMed

Zech, Astrid; Argubi-Wollesen, Andreas; Rahlf, Anna-Lina

2015-01-01

In recreational sports, uncushioned, light-weight and minimalist shoes are increasingly used to imitate barefoot situations. Uncertainty exists whether these shoes provide sufficient stability during challenging movements. In this randomised crossover study, 35 healthy distance runners performed jump landing stabilisation and single-leg stance tests on a force plate, using four conditions in random order: barefoot, uncushioned minimalist shoes, cushioned ultraflexible shoes and standard running shoes. Ground reaction force (GRF) and centre of pressure (COP) data were used to determine unilateral jump landing stabilisation time and COP sway velocity during single-leg stance. Repeated measures analysis of variance revealed significant footwear interactions for medial-lateral (p < 0.001) and anterior-posterior COP sway velocity during standing (p < 0.001). The barefoot condition produced significantly greater postural sway velocities (p < 0.001) compared to all footwear conditions. No significant effects were found for jump landing stabilisation time. In conclusion, the results of this study indicate that increased shoe flexibility and reduced sole support have no, or only minor influence on static and dynamic postural control, and therefore, may not increase the risk of traumatic events during sports activities. However, barefoot conditions should be considered carefully when adequate postural control is needed.

More symmetrical gait after split-belt treadmill walking does not modify dynamic and postural balance in individuals post-stroke.

PubMed

Miéville, Carole; Lauzière, Séléna; Betschart, Martina; Nadeau, Sylvie; Duclos, Cyril

2018-04-24

Spontaneous gait is often asymmetrical in individuals post-stroke, despite their ability to walk more symmetrically on demand. Given the sensorimotor deficits in the paretic limb, this asymmetrical gait may facilitate balance maintenance. We used a split-belt walking protocol to alter gait asymmetry and determine the effects on dynamic and postural balance. Twenty individuals post-stroke walked on a split-belt treadmill. In two separate periods, the effects of walking with the non-paretic leg, and then the paretic one, on the faster belt on spatio-temporal symmetry and balance were compared before and after these perturbation periods. Kinematic and kinetic data were collected using a motion analysis system and an instrumented treadmill to determine symmetry ratios of spatiotemporal parameters and dynamic and postural balance. Balance, quantified by the concepts of stabilizing and destabilizing forces, was compared before and after split-belt walking for subgroups of participants who improved and worsened their symmetry. The side on the slow belt during split-belt walking, but not the changes in asymmetry, affected balance. Difficulty in maintaining balance was higher during stance phase of the leg that was on the slow belt and lower on the contralateral side after split-belt walking, mostly because the center of pressure was closer (higher difficulty) or further (lower difficulty) from the limit of the base of support, respectively. Changes in spatiotemporal parameters may be sought without additional alteration of balance during gait post-stroke. Copyright © 2018 Elsevier Ltd. All rights reserved.

Reliability and Construct Validity of Limits of Stability Test in Adolescents Using a Portable Forceplate System.

PubMed

Alsalaheen, Bara; Haines, Jamie; Yorke, Amy; Broglio, Steven P

2015-12-01

To examine the reliability, convergent, and discriminant validity of the limits of stability (LOS) test to assess dynamic postural stability in adolescents using a portable forceplate system. Cross-sectional reliability observational study. School setting. Adolescents (N=36) completed all measures during the first session. To examine the reliability of the LOS test, a subset of 15 participants repeated the LOS test after 1 week. Not applicable. Outcome measurements included the LOS test, Balance Error Scoring System, Instrumented Balance Error Scoring System, and Modified Clinical Test for Sensory Interaction on Balance. A significant relation was observed among LOS composite scores (r=.36-.87, P<.05). However, no relation was observed between LOS and static balance outcome measurements. The reliability of the LOS composite scores ranged from moderate to good (intraclass correlation coefficient model 2,1=.73-.96). The results suggest that the LOS composite scores provide unique information about dynamic postural stability, and the LOS test completed at 100% of the theoretical limit appeared to be a reliable test of dynamic postural stability in adolescents. Clinicians should use dynamic balance measurement as part of their balance assessment and should not use static balance testing (eg, Balance Error Scoring System) to make inferences about dynamic balance, especially when balance assessment is used to determine rehabilitation outcomes, or when making return to play decisions after injury. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Influence of single hindlimb support during simulated weightlessness in the rat

NASA Technical Reports Server (NTRS)

Stump, Craig S.; Overton, J. Michael; Tipton, Charles M.

1990-01-01

A study was carried out to develop and evaluate a hindlimb suspension model, making it possible to differentiate the effects of non-weight bearing by hindlimbs per se from the systemic influence of simulated weightlessness. A support platform was designed which allowed the animal to maintain one hindlimb in a posture similar to the hindlimbs of the control animals at rest and to maintain one hindlimb in a posture similar to the hindlimbs of the control animals, providing a support for the animal to contract or stretch hindlimb muscles against at any time during suspension. The results of this study indicated that hindlimb support during head-down suspension will maintain muscle-mass/body-mass ratios, glycogen concentration, and blood flow. However, it will not prevent the loss in citrate synthase activity associated with conditions of simulated weightlessness.

Neural basis of postural focus effect on concurrent postural and motor tasks: phase-locked electroencephalogram responses.

PubMed

Huang, Cheng-Ya; Zhao, Chen-Guang; Hwang, Ing-Shiou

2014-11-01

Dual-task performance is strongly affected by the direction of attentional focus. This study investigated neural control of a postural-suprapostural procedure when postural focus strategy varied. Twelve adults concurrently conducted force-matching and maintained stabilometer stance with visual feedback on ankle movement (visual internal focus, VIF) and on stabilometer movement (visual external focus, VEF). Force-matching error, dynamics of ankle and stabilometer movements, and event-related potentials (ERPs) were registered. Postural control with VEF caused superior force-matching performance, more complex ankle movement, and stronger kinematic coupling between the ankle and stabilometer movements than postural control with VIF. The postural focus strategy also altered ERP temporal-spatial patterns. Postural control with VEF resulted in later N1 with less negativity around the bilateral fronto-central and contralateral sensorimotor areas, earlier P2 deflection with more positivity around the bilateral fronto-central and ipsilateral temporal areas, and late movement-related potential commencing in the left frontal-central area, as compared with postural control with VIF. The time-frequency distribution of the ERP principal component revealed phase-locked neural oscillations in the delta (1-4Hz), theta (4-7Hz), and beta (13-35Hz) rhythms. The delta and theta rhythms were more pronounced prior to the timing of P2 positive deflection, and beta rebound was greater after the completion of force-matching in VEF condition than VIF condition. This study is the first to reveal the neural correlation of postural focusing effect on a postural-suprapostural task. Postural control with VEF takes advantage of efficient task-switching to facilitate autonomous postural response, in agreement with the "constrained-action" hypothesis. Copyright © 2014 Elsevier B.V. All rights reserved.

Artificial Intelligence Software for Assessing Postural Stability

NASA Technical Reports Server (NTRS)

Lieberman, Erez; Forth, Katharine; Paloski, William

2013-01-01

A software package reads and analyzes pressure distributions from sensors mounted under a person's feet. Pressure data from sensors mounted in shoes, or in a platform, can be used to provide a description of postural stability (assessing competence to deficiency) and enables the determination of the person's present activity (running, walking, squatting, falling). This package has three parts: a preprocessing algorithm for reading input from pressure sensors; a Hidden Markov Model (HMM), which is used to determine the person's present activity and level of sensing-motor competence; and a suite of graphical algorithms, which allows visual representation of the person's activity and vestibular function over time.

Comparing Postural Stability Entropy Analyses to Differentiate Fallers and Non-Fallers

PubMed Central

Fino, Peter C.; Mojdehi, Ahmad R.; Adjerid, Khaled; Habibi, Mohammad; Lockhart, Thurmon E.; Ross, Shane D.

2015-01-01

The health and financial cost of falls has spurred research to differentiate the characteristics of fallers and non-fallers. Postural stability has received much of the attention with recent studies exploring various measures of entropy. This study compared the discriminatory ability of several entropy methods at differentiating two paradigms in the center-of-pressure (COP) of elderly individuals: 1.) eyes open (EO) versus eyes closed (EC) and 2.) fallers (F) versus non-fallers (NF). Methods were compared using the area under the curve (AUC) of the receiver-operating characteristic (ROC) curves developed from logistic regression models. Overall, multiscale entropy (MSE) and composite multiscale entropy (CompMSE) performed the best with AUCs of 0.71 for EO/EC and 0.77 for F/NF. When methods were combined together to maximize the AUC, the entropy classifier had an AUC of for 0.91 the F/NF comparison. These results suggest researchers and clinicians attempting to create clinical tests to identify fallers should consider a combination of every entropy method when creating a classifying test. Additionally, MSE and CompMSE classifiers using polar coordinate data outperformed rectangular coordinate data, encouraging more research into the most appropriate time series for postural stability entropy analysis. PMID:26464267

Effects of Peripheral Vestibular Dysfunction on Dynamic Postural Stability Measured by the Functional Reach Test and Timed Up and Go Test.

PubMed

Nishi, Toshiko; Kamogashira, Teru; Fujimoto, Chisato; Kinoshita, Makoto; Egami, Naoya; Sugasawa, Keiko; Yamasoba, Tatsuya; Iwasaki, Shinichi

2017-06-01

To investigate the influence of vestibular function on dynamic postural stability assessed by the functional reach test (FRT) and the timed up and go test (TUG). Retrospective study. Tertiary referral center. The FRT and TUG were performed in 399 patients with dizziness. The effects of peripheral vestibular dysfunction assessed by the caloric test and cervical vestibular evoked myogenic potentials (cVEMPs) to air-conducted sound (500 Hz, tone burst) on the results of FRT and TUG were analyzed. Neither FRT nor TUG scores showed significant differences in relation to the results of the caloric test ( P > .3). The FRT scores in patients who showed abnormal cVEMP responses on both sides were significantly smaller than those in patients who showed normal cVEMP responses ( P < .01). The TUG scores in patients who showed abnormal cVEMP responses on both sides were significantly greater than those in patients who showed normal cVEMP responses ( P < .05). The vestibulo-spinal reflex mediated by the saccule and its afferents is one of the factors that influence the maintenance of dynamic postural stability as measured by FRT and TUG.

Comparing Postural Stability Entropy Analyses to Differentiate Fallers and Non-fallers.

PubMed

Fino, Peter C; Mojdehi, Ahmad R; Adjerid, Khaled; Habibi, Mohammad; Lockhart, Thurmon E; Ross, Shane D

2016-05-01

The health and financial cost of falls has spurred research to differentiate the characteristics of fallers and non-fallers. Postural stability has received much of the attention with recent studies exploring various measures of entropy. This study compared the discriminatory ability of several entropy methods at differentiating two paradigms in the center-of-pressure of elderly individuals: (1) eyes open (EO) vs. eyes closed (EC) and (2) fallers (F) vs. non-fallers (NF). Methods were compared using the area under the curve (AUC) of the receiver-operating characteristic curves developed from logistic regression models. Overall, multiscale entropy (MSE) and composite multiscale entropy (CompMSE) performed the best with AUCs of 0.71 for EO/EC and 0.77 for F/NF. When methods were combined together to maximize the AUC, the entropy classifier had an AUC of for 0.91 the F/NF comparison. These results suggest researchers and clinicians attempting to create clinical tests to identify fallers should consider a combination of every entropy method when creating a classifying test. Additionally, MSE and CompMSE classifiers using polar coordinate data outperformed rectangular coordinate data, encouraging more research into the most appropriate time series for postural stability entropy analysis.

Improved postural control after dynamic balance training in older overweight women.

PubMed

Bellafiore, Marianna; Battaglia, Giuseppe; Bianco, Antonino; Paoli, Antonio; Farina, Felicia; Palma, Antonio

2011-01-01

Many studies have reported a greater frequency of falls among older women than men in conditions which stress balance. Previously, we found an improvement in static balance in older women with an increased support surface area and equal load redistribution on both feet, in response to a dynamic balance training protocol. The aim of the present study was to examine whether the same training program and body composition would have effects on the postural control of older overweight women. Ten healthy women (68.67 ± 5.50 yrs; 28.17 ± 3.35 BMI) participated in a five-week physical activity program. This included dynamic balance exercises, such as heel-to-toe walking in different directions, putting their hands on their hips, eyes open (EO) or closed (EC), with a tablet on their heads, going up and down one step, and walking on a mat. Postural stability was assessed before and after training with an optoelectronic platform and a uni-pedal balance performance test. Body composition of the trunk, upper limbs and lower limbs was measured by bio-impedance analysis. The mean speed (MS), medial-lateral MS (MS-x), anterior-posterior MS (MS-y), sway path (SP) and ellipse surface area (ESA) of the pressure center was reduced after training in older women. However, only MS, MS-x, MS-y and SP significantly decreased in bipodalic conditions with EO and MS-y also with EC (p<0.05). Instead, in monopodalic conditions, we found a significant reduction in the ESA of both feet with EO and EC. These data were associated with a significant increase in the lean mass of lower limbs and a higher number of participants who improved their ability to maintain unipedal static balance. Our dynamic balance training protocol appears to be feasible, safe and repeatable for older overweight women and to have positive effects in improving their lateral and anterior-posterior postural control, mainly acting on the visual and skeletal muscle components of the balance control system.

Kinematic Characteristics of the Posture Corrective Responses After 6 Hours Exposure to Support Withdrawal Environment

NASA Technical Reports Server (NTRS)

Sayenko D.; Miller, T.; Sayenko. I.; Kozlovskaya, I.; Reschke, M.

2004-01-01

Posture disorders are an inevitable consequence of exposure to microgravity . However, the role of different sensorimotor and sensory factors on postural function at different stages of the exposure to microgravity still remains unknown. The results obtained in a 6 hr dry immersion (DI) study where chest pushes served as a pre- and post-immersion perturbation, and DI was used as an analog of microgravity suggest that in addition to vestibular contributions, postural control may be related to a reduction of support loading and consequent decline of the tone of anti-gravitational muscles. Analysis of postural video data in response to chest pushes obtained before and after DI indicate that the structure of corrective responses was modified so that postural perturbations from threshold to moderate pushes showed a significant rise in the amplitude of ankle and knee angular displacement. With push intensity near the submaximal level, equilibrium was maintained by the elimination of excessive degrees of freedom; as manifested by the restriction of the hip joints mobility when coupled with a reduction of the knee and ankle displacement. These results suggest that DI increases the sensitivity of the posture control system by making posture control more rigid reflecting a change of the weight bearing receptors.

MODIFIED PATH METHODOLOGY FOR OBTAINING INTERVAL-SCALED POSTURAL ASSESSMENTS OF FARMWORKERS.

PubMed

Garrison, Emma B; Dropkin, Jonathan; Russell, Rebecca; Jenkins, Paul

2018-01-29

Agricultural workers perform tasks that frequently require awkward and extreme postures that are associated with musculoskeletal disorders (MSDs). The PATH (Posture, Activity, Tools, Handling) system currently provides a sound methodology for quantifying workers' exposure to these awkward postures on an ordinal scale of measurement, which places restrictions on the choice of analytic methods. This study reports a modification of the PATH methodology that instead captures these postures as degrees of flexion, an interval-scaled measurement. Rather than making live observations in the field, as in PATH, the postural assessments were performed on photographs using ImageJ photo analysis software. Capturing the postures in photographs permitted more careful measurement of the degrees of flexion. The current PATH methodology requires that the observer in the field be trained in the use of PATH, whereas the single photographer used in this modification requires only sufficient training to maintain the proper camera angle. Ultimately, these interval-scale measurements could be combined with other quantitative measures, such as those produced by electromyograms (EMGs), to provide more sophisticated estimates of future risk for MSDs. Further, these data can provide a baseline from which the effects of interventions designed to reduce hazardous postures can be calculated with greater precision. Copyright© by the American Society of Agricultural Engineers.

Gait post-stroke: Pathophysiology and rehabilitation strategies.

PubMed

Beyaert, C; Vasa, R; Frykberg, G E

2015-11-01

We reviewed neural control and biomechanical description of gait in both non-disabled and post-stroke subjects. In addition, we reviewed most of the gait rehabilitation strategies currently in use or in development and observed their principles in relation to recent pathophysiology of post-stroke gait. In both non-disabled and post-stroke subjects, motor control is organized on a task-oriented basis using a common set of a few muscle modules to simultaneously achieve body support, balance control, and forward progression during gait. Hemiparesis following stroke is due to disruption of descending neural pathways, usually with no direct lesion of the brainstem and cerebellar structures involved in motor automatic processes. Post-stroke, improvements of motor activities including standing and locomotion are variable but are typically characterized by a common postural behaviour which involves the unaffected side more for body support and balance control, likely in response to initial muscle weakness of the affected side. Various rehabilitation strategies are regularly used or in development, targeting muscle activity, postural and gait tasks, using more or less high-technology equipment. Reduced walking speed often improves with time and with various rehabilitation strategies, but asymmetric postural behaviour during standing and walking is often reinforced, maintained, or only transitorily decreased. This asymmetric compensatory postural behaviour appears to be robust, driven by support and balance tasks maintaining the predominant use of the unaffected side over the initially impaired affected side. Based on these elements, stroke rehabilitation including affected muscle strengthening and often stretching would first need to correct the postural asymmetric pattern by exploiting postural automatic processes in various particular motor tasks secondarily beneficial to gait. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Postural analysis in time and frequency domains in patients with Ehlers-Danlos syndrome.

PubMed

Galli, Manuela; Rigoldi, Chiara; Celletti, Claudia; Mainardi, Luca; Tenore, Nunzio; Albertini, Giorgio; Camerota, Filippo

2011-01-01

The goal of this work is to analyze postural control in Ehlers-Danlos syndrome (EDS) participants in time and frequency domain. This study considered a pathological group composed by 22 EDS participants performing a postural test consisting in maintaining standing position over a force platform for 30s in two conditions: open eyes (OE) and closed eyes (CE). In order to compare pathological group we acquired in the same conditions a control group composed by 20 healthy participants. The obtained center of pressure (COP) signal was analyzed in time and frequency domain using an AR model. Results revealed differences between pathological and control group: EDS participants pointed out difficulties in controlling COP displacements trying to keep it inside the BOS in AP direction and for this reason increased the use of ML mechanism in order to avoid the risk of fall. Also in CE conditions they demonstrated more difficulties in maintaining posture revealing the proprioceptive system is impaired, due to ligament laxity that characterized EDS participants. Frequency domain analysis showed no differences between the two groups, affirming that the changes in time domain reflected really the impairment to the postural control mechanism and not a different strategy assumed by EDS participants. These data could help in decision-making process to establish a correct rehabilitation approach, based on the reinforcing of muscle tone to supply the ligament laxity in order to prevent risks of falls and its consequences. Copyright © 2010 Elsevier Ltd. All rights reserved.

Effects of the lower extremities muscle activation during muscular strength training on an unstable platform with magneto-rheological dampers

NASA Astrophysics Data System (ADS)

Piao, YongJun; Choi, YounJung; Kim, JungJa; Kwan, TaeKyu; Kim, Nam-Gyun

2009-03-01

Adequate postural balance depends on the spatial and temporal integration of vestibular, visual, and somatosensory information. Especially, the musculoskeletal function (range of joint, flexibility of spine, muscular strength) is essential in maintaining the postural balance. Muscular strength training methods include the use of commercialized devices and repeatable resistance training tools (rubber band, ball, etc). These training systems cost high price and can't control of intensity. Thus we suggest a new training system which can adjust training intensity and indicate the center of pressure of a subject while the training was passively controlled by applying controlled electric current to the Magneto- Rheological damper. And we performed experimental studies on the muscular activities in the lower extremities during maintaining, moving and pushing exercises on an unstable platform with Magneto rheological dampers. A subject executed the maintaining, moving and pushing exercises which were displayed in a monitor. The electromyographic signals of the eight muscles in lower extremities were recorded and analyzed in the time and frequency domain: the muscles of interest were rectus femoris, biceps femoris, tensor fasciae latae, vastus lateralis, vastus medialis, gastrocnemius, tibialis anterior, and soleus. The experimental results showed the difference of muscular activities at the four moving exercises and the nine maintaining exercises. The rate of the increase in the muscular activities was affected by the condition of the unstable platform with MR dampers for the maintaining and moving exercises. The experimental results suggested the choice of different maintaining and moving exercises could selectively train different muscles with varying intensity. Furthermore, the findings also suggested the training using this system can improve the ability of postural balance.

Dynamic Determinants of the Uncontrolled Manifold during Human Quiet Stance

PubMed Central

Suzuki, Yasuyuki; Morimoto, Hiroki; Kiyono, Ken; Morasso, Pietro G.; Nomura, Taishin

2016-01-01

Human postural sway during stance arises from coordinated multi-joint movements. Thus, a sway trajectory represented by a time-varying postural vector in the multiple-joint-angle-space tends to be constrained to a low-dimensional subspace. It has been proposed that the subspace corresponds to a manifold defined by a kinematic constraint, such that the position of the center of mass (CoM) of the whole body is constant in time, referred to as the kinematic uncontrolled manifold (kinematic-UCM). A control strategy related to this hypothesis (CoM-control-strategy) claims that the central nervous system (CNS) aims to keep the posture close to the kinematic-UCM using a continuous feedback controller, leading to sway patterns that mostly occur within the kinematic-UCM, where no corrective control is exerted. An alternative strategy proposed by the authors (intermittent control-strategy) claims that the CNS stabilizes posture by intermittently suspending the active feedback controller, in such a way to allow the CNS to exploit a stable manifold of the saddle-type upright equilibrium in the state-space of the system, referred to as the dynamic-UCM, when the state point is on or near the manifold. Although the mathematical definitions of the kinematic- and dynamic-UCM are completely different, both UCMs play similar roles in the stabilization of multi-joint upright posture. The purpose of this study was to compare the dynamic performance of the two control strategies. In particular, we considered a double-inverted-pendulum-model of postural control, and analyzed the two UCMs defined above. We first showed that the geometric configurations of the two UCMs are almost identical. We then investigated whether the UCM-component of experimental sway could be considered as passive dynamics with no active control, and showed that such UCM-component mainly consists of high frequency oscillations above 1 Hz, corresponding to anti-phase coordination between the ankle and hip. We also showed that this result can be better characterized by an eigenfrequency associated with the dynamic-UCM. In summary, our analysis highlights the close relationship between the two control strategies, namely their ability to simultaneously establish small CoM variations and postural stability, but also make it clear that the intermittent control hypothesis better explains the spectral characteristics of sway. PMID:27999535

Dynamic Determinants of the Uncontrolled Manifold during Human Quiet Stance.

PubMed

Suzuki, Yasuyuki; Morimoto, Hiroki; Kiyono, Ken; Morasso, Pietro G; Nomura, Taishin

2016-01-01

Human postural sway during stance arises from coordinated multi-joint movements. Thus, a sway trajectory represented by a time-varying postural vector in the multiple-joint-angle-space tends to be constrained to a low-dimensional subspace. It has been proposed that the subspace corresponds to a manifold defined by a kinematic constraint, such that the position of the center of mass (CoM) of the whole body is constant in time, referred to as the kinematic uncontrolled manifold ( kinematic-UCM ). A control strategy related to this hypothesis ( CoM-control-strategy ) claims that the central nervous system (CNS) aims to keep the posture close to the kinematic-UCM using a continuous feedback controller, leading to sway patterns that mostly occur within the kinematic-UCM, where no corrective control is exerted. An alternative strategy proposed by the authors ( intermittent control-strategy ) claims that the CNS stabilizes posture by intermittently suspending the active feedback controller, in such a way to allow the CNS to exploit a stable manifold of the saddle-type upright equilibrium in the state-space of the system, referred to as the dynamic-UCM , when the state point is on or near the manifold. Although the mathematical definitions of the kinematic- and dynamic-UCM are completely different, both UCMs play similar roles in the stabilization of multi-joint upright posture. The purpose of this study was to compare the dynamic performance of the two control strategies. In particular, we considered a double-inverted-pendulum-model of postural control, and analyzed the two UCMs defined above. We first showed that the geometric configurations of the two UCMs are almost identical. We then investigated whether the UCM-component of experimental sway could be considered as passive dynamics with no active control, and showed that such UCM-component mainly consists of high frequency oscillations above 1 Hz, corresponding to anti-phase coordination between the ankle and hip. We also showed that this result can be better characterized by an eigenfrequency associated with the dynamic-UCM. In summary, our analysis highlights the close relationship between the two control strategies, namely their ability to simultaneously establish small CoM variations and postural stability, but also make it clear that the intermittent control hypothesis better explains the spectral characteristics of sway.

Postural strategies assessed with inertial sensors in healthy and parkinsonian subjects

PubMed Central

Baston, Chiara; Mancini, Martina; Schoneburg, Bernadette; Horak, Fay; Rocchi, Laura

2015-01-01

The present study introduces a novel instrumented method to characterize postural movement strategies to maintain balance during stance (ankle and hip strategy), by means of inertial sensors, positioned on the legs and on the trunk. We evaluated postural strategies in subjects with2 types of parkinsonism: idiopathic Parkinson's disease (PD) and Progressive Supranuclear Palsy (PSP),and inage-matched control subjects standing under perturbed conditions implementedby the Sensory Organization Test (SOT).Coordination between the upper and lower segments of the body during postural sway was measured using a covariance index over time, by a sliding-window algorithm. Afterwards, a postural strategy index was computed. We also measuredthe amount of postural sway, as adjunctive information to characterize balance, by the root mean square of the horizontal trunk acceleration signal (RMS). Results showed that control subjects were able to change their postural strategy, whilst PSP and PD subjects persisted in use of an ankle strategy in all conditions.PD subjects had RMS values similar to control subjects even without changing postural strategy appropriately, whereas PSP subjects showed much larger RMS values than controls, resulting in several falls during the most challenging SOT conditions (5 and 6). Results are in accordance with the corresponding clinical literature describing postural behavior in the same kind of subjects. The proposed strategy index, based on the use ofinertial sensors on the upper and lower body segments, isa promising and unobtrusive toolto characterize postural strategies performed to attain balance. PMID:24656713

Atypical anticipatory postural adjustments during gait initiation among individuals with sub-acute stroke.

PubMed

Rajachandrakumar, Roshanth; Fraser, Julia E; Schinkel-Ivy, Alison; Inness, Elizabeth L; Biasin, Lou; Brunton, Karen; McIlroy, William E; Mansfield, Avril

2017-02-01

Anticipatory postural adjustments, executed prior to gait initiation, help preserve lateral stability when stepping. Atypical patterns of anticipatory activity prior to gait initiation may occur in individuals with unilateral impairment (e.g., stroke). This study aimed to determine the prevalence, correlates, and consequences of atypical anticipatory postural adjustment patterns prior to gait initiation in a sub-acute stroke population. Forty independently-ambulatory individuals with sub-acute stroke stood on two force plates and initiated gait at a self-selected speed. Medio-lateral centre of pressure displacement was calculated and used to define anticipatory postural adjustments (shift in medio-lateral centre of pressure >10mm from baseline). Stroke severity, motor recovery, and functional balance and mobility status were also obtained. Three patterns were identified: single (typical), absent (atypical), and multiple (atypical) anticipatory postural adjustments. Thirty-five percent of trials had atypical anticipatory postural adjustments (absent and multiple). Frequency of absent anticipatory postural adjustments was negatively correlated with walking speed. Multiple anticipatory postural adjustments were more prevalent when leading with the non-paretic than the paretic limb. Trials with multiple anticipatory postural adjustments had longer duration of anticipatory postural adjustment and time to foot-off, and shorter unloading time than trials with single anticipatory postural adjustments. A high prevalence of atypical anticipatory control prior to gait initiation was found in individuals with stroke. Temporal differences were identified with multiple anticipatory postural adjustments, indicating altered gait initiation. These findings provide insight into postural control during gait initiation in individuals with sub-acute stroke, and may inform interventions to improve ambulation in this population. Copyright © 2016 Elsevier B.V. All rights reserved.

Augmented feedback of COM and COP modulates the regulation of quiet human standing relative to the stability boundary.

PubMed

Kilby, Melissa C; Slobounov, Semyon M; Newell, Karl M

2016-06-01

The experiment manipulated real-time kinematic feedback of the motion of the whole body center of mass (COM) and center of pressure (COP) in anterior-posterior (AP) and medial-lateral (ML) directions to investigate the variables actively controlled in quiet standing of young adults. The feedback reflected the current 2D postural positions within the 2D functional stability boundary that was scaled to 75%, 30% and 12% of its original size. The findings showed that the distance of both COP and COM to the respective stability boundary was greater during the feedback trials compared to a no feedback condition. However, the temporal safety margin of the COP, that is, the virtual time-to-contact (VTC), was higher without feedback. The coupling relation of COP-COM showed stable in-phase synchronization over all of the feedback conditions for frequencies below 1Hz. For higher frequencies (up to 5Hz), there was progressive reduction of COP-COM synchronization and local adaptation under the presence of augmented feedback. The findings show that the augmented feedback of COM and COP motion differentially and adaptively influences spatial and temporal properties of postural motion relative to the stability boundary while preserving the organization of the COM-COP coupling in postural control. Copyright © 2016. Published by Elsevier B.V.

Stance Postural Strategies in Patients with Chronic Inflammatory Demyelinating Polyradiculoneuropathy

PubMed Central

Missori, Paolo; Trompetto, Carlo; Fattapposta, Francesco

2016-01-01

Introduction Polyneuropathy leads to postural instability and an increased risk of falling. We investigated how impaired motor impairment and proprioceptive input due to neuropathy influences postural strategies. Methods Platformless bisegmental posturography data were recorded in healthy subjects and patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Each subject stood on the floor, wore a head and a hip electromagnetic tracker. Sway amplitude and velocity were recorded and the mean direction difference (MDD) in the velocity vector between trackers was calculated as a flexibility index. Results Head and hip postural sway increased more in patients with CIDP than in healthy controls. MDD values reflecting hip strategies also increased more in patients than in controls. In the eyes closed condition MDD values in healthy subjects decreased but in patients remained unchanged. Discussion Sensori-motor impairment changes the balance between postural strategies that patients adopt to maintain upright quiet stance. Motor impairment leads to hip postural strategy overweight (eyes open), and prevents strategy re-balancing when the sensory context predominantly relies on proprioceptive input (eyes closed). PMID:26977594

Influence of gymnastics training on the development of postural control.

PubMed

Garcia, Claudia; Barela, José Angelo; Viana, André Rocha; Barela, Ana Maria Forti

2011-03-29

This study investigated the influence of gymnastics training on the postural control of children with and without the use of visual information. Two age groups, aged 5-7 and 9-11 years old, of gymnasts and nongymnasts were asked to maintain an upright and quiet stance on a force platform with eyes open (EO) and eyes closed (EC) for 30s. Area of the stabilogram (AOS) and mean velocity of the center of pressure (COP) in anterior-posterior (AP) and medial-lateral (ML) directions were calculated and used to investigate the effects of gymnastics training, age, and visual information. Younger gymnasts presented greater postural control compared to younger nongymnasts while visual information did not improve postural control in younger nongymnasts. Younger gymnasts displayed improved postural control with EO compared to EC. The mean velocity of the COP in the ML direction was: less for younger gymnasts than younger nongymnasts with EO. These results suggest that gymnastics training promotes improvements in postural control of younger children only, which results from their use of visual information when available. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Changes in the Vestibular System with Age: An Abstracted Bibliography,

DTIC Science & Technology

1981-04-30

group." COMMENT: Similar to other articles in this series, showing significant loss of afferents (and possibly efferents) in the vestibular nerve. k...marked dependence of postural stability on vision . In them, the disturbing optokinetic stimulus leads to a marked ipsilateral postural deviation or...SUBJECTS (Number-age): N/A EXPERIMENTAL PROCEDURES: Review FINDINGS: 1. No mention of vestibular functioning. 2. Review sections on vision , audition

The Efficacy of a Perceptive Rehabilitation on Postural Control in Patients with Chronic Nonspecific Low Back Pain

ERIC Educational Resources Information Center

Paolucci, Teresa; Fusco, Augusto; Iosa, Marco; Grasso, Maria R.; Spadini, Ennio; Paolucci, Stefano; Saraceni, Vincenzo M.; Morone, Giovanni

2012-01-01

Patients with chronic low back pain have a worse posture, probably related to poor control of the back muscles and altered perception of the trunk midline. The aim of this study was to evaluate the efficacy of a perceptive rehabilitation in terms of stability and pain relief in patients with chronic nonspecific low back pain. Thirty patients were…

Automated Assessment of Postural Stability (AAPS)

DTIC Science & Technology

2017-10-01

evaluation capability, 15 healthy subjects (7 male, 8 female) were required to perform the BESS test, while simultaneously being tracked by a Kinect 2.0...scale, specific behaviors corresponding to deficits in postural control while simultaneously spotting the subject to prevent falls. The subject under...of the error detection algorithm, we simultaneously collected data using a Kinect sensor and a 12-Camera Qualisys system. Qualisys data have been post

Postural Stability in Young Adults with Down Syndrome in Challenging Conditions

PubMed Central

Bieć, Ewa; Zima, Joanna; Wójtowicz, Dorota; Wojciechowska-Maszkowska, Bożena; Kręcisz, Krzysztof; Kuczyński, Michał

2014-01-01

To evaluate postural control and performance in subjects with Down syndrome (SwDS), we measured postural sway (COP) in quiet stance in four 20-second tests: with eyes open or closed and on hard or foam surface. Ten SwDS and eleven healthy subjects participated, aged 29.8 (4.8) and 28.4 (3.9), respectively. The time-series recorded with the sampling rate of 100 Hz were used to evaluate postural performance (COP amplitude and mean velocity) and strategies (COP frequency, fractal dimension and entropy). There were no intergroup differences in the amplitude except the stance on foam pad with eyes open when SwDS had larger sway. The COP velocity and frequency were larger in SwDS than controls in all trials on foam pad. During stances on the foam pad SwDS increased fractal dimension showing higher complexity of their equilibrium system, while controls decreased sample entropy exhibiting more conscious control of posture in comparison to the stances on hard support surface. This indicated that each group used entirely different adjustments of postural strategies to the somatosensory challenge. It is proposed that the inferior postural control of SwDS results mainly from insufficient experience in dealing with unpredictable postural stimuli and deficit in motor learning. PMID:24728178

Study on an advanced early rehabilitation training system for postural control using a tilting bed

NASA Astrophysics Data System (ADS)

Yu, Chang-Ho; Kim, Kyong; Kwon, Tae-Kyu; Hong, Chul-Un; Kim, Nam-Gyun

2005-12-01

It proposed a new early rehabilitation training system for postural control using a tilting bed, a visual display and a force plate. The conventional rehabilitation systems for postural control can't be applied to the patients lying in bed because the rehabilitation training using those systems is only possible when the patient can stand up by himself or herself. Moreover, there did not exist any device that could provide the sense of balance or the sensation of walking to the patients in bed. The software for the system consists of the training program and the analysis program. The training program was designed to improve the ability of postural control of the subjects by repeated training of moving the center of pressure (COP) applied to the forceplate. The training program consists of the COP maintaining training and the COP movement training in horizontal, vertical, 45° and -45° directions. The analysis program consists of the COP moving time analysis modules, the COP maintaining time analysis module. Through the experiments with real people, it verified the effectiveness of the new early rehabilitation training system. The results showe that this system is an effective system for early rehabilitation training and that our system might be useful as clinical equipment.

Temporal parameter change of human postural control ability during upright swing using recursive least square method

NASA Astrophysics Data System (ADS)

Goto, Akifumi; Ishida, Mizuri; Sagawa, Koichi

2010-01-01

The purpose of this study is to derive quantitative assessment indicators of the human postural control ability. An inverted pendulum is applied to standing human body and is controlled by ankle joint torque according to PD control method in sagittal plane. Torque control parameters (KP: proportional gain, KD: derivative gain) and pole placements of postural control system are estimated with time from inclination angle variation using fixed trace method as recursive least square method. Eight young healthy volunteers are participated in the experiment, in which volunteers are asked to incline forward as far as and as fast as possible 10 times over 10 [s] stationary intervals with their neck joint, hip joint and knee joint fixed, and then return to initial upright posture. The inclination angle is measured by an optical motion capture system. Three conditions are introduced to simulate unstable standing posture; 1) eyes-opened posture for healthy condition, 2) eyes-closed posture for visual impaired and 3) one-legged posture for lower-extremity muscle weakness. The estimated parameters Kp, KD and pole placements are applied to multiple comparison test among all stability conditions. The test results indicate that Kp, KD and real pole reflect effect of lower-extremity muscle weakness and KD also represents effect of visual impairment. It is suggested that the proposed method is valid for quantitative assessment of standing postural control ability.

Nonlinear Variability of Body Sway in Patients with Phobic Postural Vertigo

PubMed Central

Schniepp, Roman; Wuehr, Max; Pradhan, Cauchy; Novozhilov, Sergej; Krafczyk, Siegbert; Brandt, Thomas; Jahn, Klaus

2013-01-01

Background: Subjective postural imbalance is a key symptom in the somatoform phobic postural vertigo (PPV). It has been assumed that more attentional control of body posture and / or co-contraction of leg muscles during standing is used to minimize the physiological body sway in PPV. Here we analyze nonlinear variability of body sway in patients with PPV in order to disclose changes in postural control strategy associated with PPV. Methods: Twenty patients with PPV and 20 age-matched healthy subjects (HS) were recorded on a stabilometer platform with eyes open (EO), eyes closed (EC), and while standing on a foam rubber with eyes closed (ECF). Spatio-temporal changes of the center of pressure (CoP) displacement were analyzed to assess the structure of postural variability by computing the scaling exponent α and the sample entropy (SEn) of the time series. Results: With EO on firm ground α and SEn of CoP displacement were significantly lower in patients (p < 0.001). For more difficult conditions (EC, ECF) postural variability in PPV assimilated to that of HS. Conclusion: Postural control in PPV patients differs from HS under normal stance condition. It is characterized by a reduced scaling behavior and higher regularity. These changes in the structure of postural variability might suggest an inappropriate attentional involvement with stabilizing strategies, which are used by HS only for more demanding balance tasks. PMID:23966974

Evaluation of the temporal structure of postural sway fluctuations based on a comprehensive set of analysis tools

NASA Astrophysics Data System (ADS)

Kirchner, M.; Schubert, P.; Schmidtbleicher, D.; Haas, C. T.

2012-10-01

The analysis of postural control has a long history. Traditionally, the amount of body sway is solely used as an index of postural stability. Although this leads to some extent to an effective evaluation of balance performance, the control mechanisms involved have not yet been fully understood. The concept of nonlinear dynamics suggests that variability in the motor output is not randomness but structure, providing the stimulus to reveal the functionality of postural sway. The present work evaluates sway dynamics by means of COP excursions in a quiet standing task versus a dual-task condition in three different test times (30, 60, 300 s). Besides the application of traditional methods-which estimate the overall size of sway-the temporal pattern of body sway was quantified via wavelet transform, multiscale entropy and fractal analysis. We found higher sensitivity of the structural parameters to modulations of postural control strategies and partly an improved evaluation of sway dynamics in longer recordings. It could be shown that postural control modifications take place on different timescales corresponding to the interplay of the sensory systems. A continued application of nonlinear analysis can help to better understand postural control mechanisms.

Postural control assessment in students with normal hearing and sensorineural hearing loss.

PubMed

Melo, Renato de Souza; Lemos, Andrea; Macky, Carla Fabiana da Silva Toscano; Raposo, Maria Cristina Falcão; Ferraz, Karla Mônica

2015-01-01

Children with sensorineural hearing loss can present with instabilities in postural control, possibly as a consequence of hypoactivity of their vestibular system due to internal ear injury. To assess postural control stability in students with normal hearing (i.e., listeners) and with sensorineural hearing loss, and to compare data between groups, considering gender and age. This cross-sectional study evaluated the postural control of 96 students, 48 listeners and 48 with sensorineural hearing loss, aged between 7 and 18 years, of both genders, through the Balance Error Scoring Systems scale. This tool assesses postural control in two sensory conditions: stable surface and unstable surface. For statistical data analysis between groups, the Wilcoxon test for paired samples was used. Students with hearing loss showed more instability in postural control than those with normal hearing, with significant differences between groups (stable surface, unstable surface) (p<0.001). Students with sensorineural hearing loss showed greater instability in the postural control compared to normal hearing students of the same gender and age. Copyright © 2014 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

Postural compensation for vestibular loss and implications for rehabilitation.

PubMed

Horak, Fay B

2010-01-01

This chapter summarizes the role of the vestibular system in postural control so that specific and effective rehabilitation can be designed that facilitates compensation for loss of vestibular function. Patients with bilateral or unilateral loss of peripheral vestibular function are exposed to surface perturbations to quantify automatic postural responses. Studies also evaluated the effects of audio- and vibrotactile-biofeedback to improve stability in stance and gait. The most important role of vestibular information for postural control is to control orientation of the head and trunk in space with respect to gravitoinertial forces, particularly when balancing on unstable surfaces. Vestibular sensory references are particularly important for postural control at high frequencies and velocities of self-motion, to reduce trunk drift and variability, to provide an external reference frame for the trunk and head in space; and to uncouple coordination of the trunk from the legs and the head-in-space from the body CoM. The goal of balance rehabilitation for patients with vestibular loss is to help patients 1) use remaining vestibular function, 2) depend upon surface somatosensory information as their primary postural sensory system, 3) learn to use stable visual references, and 4) identify efficient and effective postural movement strategies.

THE COMPARISON OF THE LUMBAR MULTIFIDUS MUSCLES FUNCTION BETWEEN GYMNASTIC ATHLETES WITH SWAY-BACK POSTURE AND NORMAL POSTURE.

PubMed

Mahdavie, Elnaz; Rezasoltani, Asghar; Simorgh, Leila

2017-08-01

The prevalence of sway back posture (SBP) is very high among elite gymnasts. This posture may be partly due to the improper function of lumbar multifidus muscles (LMM) as lumbar stabilizers muscles. The aim of this study was to compare the thicknesses of LMM measured at rest and during the contraction elicited during an arm lift between elite gymnasts with SBP and normal posture. Observational, descriptive, comparative. The participants consist of twenty gymnasts between the ages of 17 and 30 who had trained in gymnastics for more than ten years. They were assigned to two groups: SBP (n=10) and control (n=10). Posture analysis with grid paper and plumb line was performed for all subjects. The thickness of LMM on dominant side of spinal column was measured by a real-time ultrasound at five lumbar levels. The thickness of the LMM was measured both at rest and during the contraction elicited during an arm lift. The variation between the LMM thickness between the muscle at rest and muscle at the peak of contraction was regarded as LMM muscle function. The thickness of LMM was less in SBP group than the control group at all lumbar segments. The variation in LMM thickness between the state of rest and muscle contraction was significantly less in athletes with SBP than controls when compared at all levels of the lumbar spine (p < 0.05). The function of LMM may be disturbed in athletes with SBP as demonstrated by decreased thicknesses of LMM found in gymnasts with SBP. Additionally, the thickness of the LMM as a strong antigravity and stabilizing muscle group was decreased during arm raising in gymnasts with SBP. 3a.

A preliminary study of static and dynamic balance in sedentary obese young adults: the relationship between BMI, posture and postural balance.

PubMed

do Nascimento, J A; Silva, C C; Dos Santos, H H; de Almeida Ferreira, J J; de Andrade, P R

2017-12-01

The aim of this study was to evaluate the postural control of obese young adults with normal body mass index during different static (bipedic and unipedic support) and dynamic postural conditions (gait velocity and limits of stability) in order to compare the static and dynamic balance of these individuals. A cross-sectional quantitative study was carried out to evaluate static and dynamic balance in 25 sedentary individuals. The sample was divided into two groups, 10 in the normal-weight group (24.70 ± 3.89 years and 21.5 ± 1.66 kg m -2 ) and 15 in the obese group (26.80 ± 5.16 years and 35.66 ± 4.29 kg m -2 ). Postural evaluation was performed through visual inspection, and balance analyses were performed using the Timed Up & Go test (TUGT) and Balance System (Biodex). Descriptive analyses, Fisher's exact test and Mann Whitney U-tests were performed using the Statistical Package for Social Sciences (SPSS - 20.0, Armonk, NY) software. Most of the obese volunteers presented postural alterations, such as head protrusion (47.6%), hyperkyphosis (46.7%) and hyperlordosis (26.7%). Medial-lateral dynamic displacement, risk of falls and mean time to perform the limits of stability test and TUGT were higher for obese subjects (P < 0.05), while there were no significant differences between the groups (P > 0.05) for static balance tests for either bipedal or unipedal tasks. The disadvantage presented by the young obese subjects occurs in dynamic activities, representing worse balance and an increase in time needed to accomplish these activities. © 2017 World Obesity Federation.

Understanding balance differences in individuals with multiple sclerosis with mild disability: an investigation of differences in sensory feedback on postural control during a Romberg task.

PubMed

Denommé, Luke T; Mandalfino, Patricia; Cinelli, Michael E

2014-06-01

A major presenting symptom in 'individuals with multiple sclerosis with mild balance disability' (IwMS) is poor postural control, resulting from slowed spinal somatosensory conduction. Postural control deficits in IwMS are most apparent when vision is removed and the base of support is reduced such is the case during tandem and single support stances. The current study used center of pressure (COP) measurements to determine whether postural control differences exist between IwMS and either 'healthy age-matched individuals' (HAMI) or 'community-dwelling older adults' (OA). Postural control was evaluated using a Romberg standing task, which required participants to stand with their feet together and hands by their sides for 45 s with either their eyes open or closed. Results revealed that COP velocity root mean square was greater in IwMS and their COP position was closer to their self-selected maximum stability limits (e.g., greater Standing Index proportion) when vision was removed compared to HAMI. Conversely, IwMS displayed similar postural control characteristics to OA. The current study highlights two novel findings: (1) the utility of novel COP measurements to assess differences in the level of postural control in IwMS; and (2) the benefit of assessing postural control levels in IwMS to not only a population with a fully intact and functional postural control system (HAMI) but also to another population that is thought to experience postural control deficits (OA).

Impaired perception of surface tilt in progressive supranuclear palsy

PubMed Central

Dale, Marian L.; Horak, Fay B.; Wright, W. Geoffrey; Schoneburg, Bernadette M.; Nutt, John G.; Mancini, Martina

2017-01-01

Introduction Progressive supranuclear palsy (PSP) is characterized by early postural instability and backward falls. The mechanisms underlying backward postural instability in PSP are not understood. The aim of this study was to test the hypothesis that postural instability in PSP is a result of dysfunction in the perception of postural verticality. Methods We gathered posturography data on 12 subjects with PSP to compare with 12 subjects with idiopathic Parkinson’s Disease (PD) and 12 healthy subjects. Objective tests of postural impairment included: dynamic sensory perception tests of gravity and of surface oscillations, postural responses to surface perturbations, the sensory organization test of postural sway under altered sensory conditions and limits of stability in stance. Results Perception of toes up (but not toes down) surface tilt was reduced in subjects with PSP compared to both control subjects (p≤0.001 standing, p≤0.007 seated) and subjects with PD (p≤0.03 standing, p≤0.04 seated). Subjects with PSP, PD and normal controls accurately perceived the direction of gravity when standing on a tilting surface. Unlike PD and control subjects, subjects with PSP exerted less postural corrective torque in response to toes up surface tilts. Discussion Difficulty perceiving backward tilt of the surface or body may account for backward falls and postural impairments in patients with PSP. These observations suggest that abnormal central integration of sensory inputs for perception of body and surface orientation contributes to the pathophysiology of postural instability in PSP. PMID:28267762

The influence of an immersive virtual environment on the segmental organization of postural stabilizing responses.

PubMed

Keshner, E A; Kenyon, R V

2000-01-01

We examined the effect of a 3-dimensional stereoscopic scene on segmental stabilization. Eight subjects participated in static sway and locomotion experiments with a visual scene that moved sinusoidally or at constant velocity about the pitch or roll axes. Segmental displacements, Fast Fourier Transforms, and Root Mean Square values were calculated. In both pitch and roll, subjects exhibited greater magnitudes of motion in head and trunk than ankle. Smaller amplitudes and frequent phase reversals suggested control of the ankle by segmental proprioceptive inputs and ground reaction forces rather than by the visual-vestibular signals. Postural controllers may set limits of motion at each body segment rather than be governed solely by a perception of the visual vertical. Two locomotor strategies were also exhibited, implying that some subjects could override the effect of the roll axis optic flow field. Our results demonstrate task dependent differences that argue against using static postural responses to moving visual fields when assessing more dynamic tasks.

Virtual Reality Telerehabilitation for Postural Instability in Parkinson's Disease: A Multicenter, Single-Blind, Randomized, Controlled Trial

PubMed Central

Geroin, Christian; Dimitrova, Eleonora; Boldrini, Paolo; Waldner, Andreas; Bonadiman, Silvia; Regazzo, Sara; Stirbu, Elena; Primon, Daniela; Bosello, Christian; Gravina, Aristide Roberto; Peron, Luca; Trevisan, Monica; Garcia, Alberto Carreño; Menel, Alessia; Bloccari, Laura; Valè, Nicola; Saltuari, Leopold; Tinazzi, Michele

2017-01-01

Introduction Telerehabilitation enables patients to access remote rehabilitation services for patient-physiotherapist videoconferencing in their own homes. Home-based virtual reality (VR) balance training has been shown to reduce postural instability in patients with Parkinson's disease (PD). The primary aim was to compare improvements in postural stability after remotely supervised in-home VR balance training and in-clinic sensory integration balance training (SIBT). Methods In this multicenter study, 76 PD patients (modified Hoehn and Yahr stages 2.5–3) were randomly assigned to receive either in-home VR telerehabilitation (n = 38) or in-clinic SIBT (n = 38) in 21 sessions of 50 minutes each, 3 days/week for 7 consecutive weeks. VR telerehabilitation consisted of graded exergames using the Nintendo Wii Fit system; SIBT included exercises to improve postural stability. Patients were evaluated before treatment, after treatment, and at 1-month follow-up. Results Analysis revealed significant between-group differences in improvement on the Berg Balance Scale for the VR telerehabilitation group (p = 0.04) and significant Time × Group interactions in the Dynamic Gait Index (p = 0.04) for the in-clinic group. Both groups showed differences in all outcome measures over time, except for fall frequency. Cost comparison yielded between-group differences in treatment and equipment costs. Conclusions VR is a feasible alternative to in-clinic SIBT for reducing postural instability in PD patients having a caregiver. PMID:29333454

The role of haptic cues from rough and slippery surfaces in human postural control

NASA Technical Reports Server (NTRS)

Jeka, J. J.; Lackner, J. R.

1995-01-01

Haptic information is critically important in complex sensory-motor tasks such as manipulating objects. Its comparable importance in spatial orientation is only beginning to be recognized. We have shown that postural sway in humans is significantly reduced by lightly touching a stable surface with a fingertip at contact force levels far below those physically necessary to stabilize the body. To investigate further the functional relationship between contact forces at the hand and postural equilibrium, we had subjects stand in the tandem Romberg stance while being allowed physically supportive (force contact) and non-physically supportive (touch contact) amounts of index fingertip force on surfaces with different frictional characteristics. Mean sway amplitude (MSA) was reduced by over 50% with both touch and force contact of the fingertip, compared to standing without fingertip contact. No differences in MSA were observed when touching rough or slippery surfaces. The amplitude of EMG activity in the peroneal muscles and the timing relationships between fingertip forces, body sway and EMG activity suggested that with touch contact of the finger or with force contact on a slippery surface long-loop "reflexes" involving postural muscles were stabilizing sway. With force contact of the fingertip on a rough surface, MSA reduction was achieved primarily through physical support of the body. This pattern of results indicates that light touch contact cues from the fingertip in conjunction with proprioceptive signals about arm configuration are providing information about body sway that can be used to reduce MSA through postural muscle activation.

Postural control in 13-year-old soccer players

PubMed Central

Bieć, Ewa

2010-01-01

To evaluate the effect of early systematic soccer training on postural control we measured center-of-pressure (COP) variability, range, mean velocity and frequency in bipedal quiet stance with eyes open (EO) and closed (EC) in 44 boys aged 13 (25 boys who practiced soccer for 5–6 years and 19 healthy boys who did not practice sports). The soccer players had better stability, particularly in the medial–lateral plane (M/L); their COP variability and range were lower than in controls in both EO (p < 0.05) and EC (p < 0.0005) condition indicating that the athletes were less dependent on vision than non-athletes. Improved stability of athletes was accompanied by a decrease in COP frequency (p < 0.001 in EO, and p < 0.04 in EC) which accounted for lower regulatory activity of balance system in soccer players. The athletes had lower COP mean velocity than controls (p < 0.0001 in both visual condition), with larger difference in the M/L than A/P plane (p < 0.00001 and p < 0.05, respectively). Postural behavior was more variable within the non-athletes than soccer players, mainly in the EC stances (p < 0.005 for all COP parameters). We conclude that: (1) soccer training described was efficient in improving the M/L postural control in young boys; (2) athletes developed specific postural strategies characterized by decreased COP frequency and lower reliance on vision. PMID:20582432

Recent inner ear specialization for high-speed hunting in cheetahs.

PubMed

Grohé, Camille; Lee, Beatrice; Flynn, John J

2018-02-02

The cheetah, Acinonyx jubatus, is the fastest living land mammal. Because of its specialized hunting strategy, this species evolved a series of specialized morphological and functional body features to increase its exceptional predatory performance during high-speed hunting. Using high-resolution X-ray computed micro-tomography (μCT), we provide the first analyses of the size and shape of the vestibular system of the inner ear in cats, an organ essential for maintaining body balance and adapting head posture and gaze direction during movement in most vertebrates. We demonstrate that the vestibular system of modern cheetahs is extremely different in shape and proportions relative to other cats analysed (12 modern and two fossil felid species), including a closely-related fossil cheetah species. These distinctive attributes (i.e., one of the greatest volumes of the vestibular system, dorsal extension of the anterior and posterior semicircular canals) correlate with a greater afferent sensitivity of the inner ear to head motions, facilitating postural and visual stability during high-speed prey pursuit and capture. These features are not present in the fossil cheetah A. pardinensis, that went extinct about 126,000 years ago, demonstrating that the unique and highly specialized inner ear of the sole living species of cheetah likely evolved extremely recently, possibly later than the middle Pleistocene.

Intrarater test-retest reliability of static and dynamic stability indexes measurement using the Biodex Stability System during unilateral stance.

PubMed

Arifin, Nooranida; Abu Osman, Noor Azuan; Wan Abas, Wan Abu Bakar

2014-04-01

The measurements of postural balance often involve measurement error, which affects the analysis and interpretation of the outcomes. In most of the existing clinical rehabilitation research, the ability to produce reliable measures is a prerequisite for an accurate assessment of an intervention after a period of time. Although clinical balance assessment has been performed in previous study, none has determined the intrarater test-retest reliability of static and dynamic stability indexes during dominant single stance. In this study, one rater examined 20 healthy university students (female=12, male=8) in two sessions separated by 7 day intervals. Three stability indexes--the overall stability index (OSI), anterior/posterior stability index (APSI), and medial/ lateral stability index (MLSI) in static and dynamic conditions--were measured during single dominant stance. Intraclass correlation coefficient (ICC), standard error measurement (SEM) and 95% confidence interval (95% CI) were calculated. Test-retest ICCs for OSI, APSI, and MLSI were 0.85, 0.78, and 0.84 during static condition and were 0.77, 0.77, and 0.65 during dynamic condition, respectively. We concluded that the postural stability assessment using Biodex stability system demonstrates good-to-excellent test-retest reliability over a 1 week time interval.

Analysis of healthy sitting behavior: interface pressure distribution and subcutaneous tissue oxygenation.

PubMed

Reenalda, Jasper; Van Geffen, Paul; Nederhand, Marc; Jannink, Michiel; IJzerman, Maarten; Rietman, Hans

2009-01-01

Pressure ulcers are a large problem in individuals who use a wheelchair for their mobility and have limited trunk stability and motor function. Because no relation between interface pressure and pressure ulcer development has been established and no clinical threshold for pressure ulcer development can be given, looking at the sitting behavior of nondisabled individuals is important. Nondisabled individuals do not develop pressure ulcers because they continuously shift posture. We analyzed the sitting behavior of 25 nondisabled male subjects by using a combination of interface pressure measurement and subcutaneous tissue oxygenation measurement by means of the Oxygen to See. These subjects shifted posture on average 7.8 +/- 5.2 times an hour. These posture shifts were merely a combination of posture shifts in the frontal and sagittal plane. Subcutaneous oxygen saturation increased on average 2.2% with each posture adjustment, indicating a positive effect of posture shifts on tissue viability. The results of this study can be used as a reference for seating interventions aimed at preventing pressure ulcers. Changing the sitting load at least every 8 minutes is recommended for wheelchair users.

The effects of prosthetic foot type and visual alteration on postural steadiness in below-knee amputees

PubMed Central

2014-01-01

Background Achieving independent upright posture has known to be one of the main goals in rehabilitation following lower limb amputation. The purpose of this study was to compare postural steadiness of below knee amputees with visual alterations while wearing three different prosthetic feet. Methods Ten male below-knee amputees were instructed to stand quietly on the Biodex® balance platform while wearing solid ankle cushion heel (SACH), single axis (SA) and energy storage and release (ESAR) prosthetic foot under different visual input conditions (eyes-opened and eyes-closed). The overall stability index (OSI), anterior- posterior stability index (APSI), and medial-lateral stability index (MLSI) were computed. Perceived balance assessment of each foot was evaluated using Activities-specific Balance Confidence (ABC) score. Results The findings highlights that SACH showed lowest overall stability index (indicating less body sway) during eyes-opened (OSI: SACH = 1.09, SA = 1.58, ESAR = 1.59) and SA showed lowest overall stability index during eyes-closed (OSI: SACH = 2.52, SA = 2.30, ESAR = 2.76) condition. However, overall stability indexes between foot types did not differ significantly during eyes-opened or eyes-closed (p = 0.651). There was a trend of instability which occurred more in medial-lateral compared to anterior-posterior direction for all foot types, with significant result in ESAR foot(eyes-opened: MLSI = 1.59, APSI = 0.65, p = 0.034; eyes-closed: MLSI = 2.76, APSI = 1.80, p = 0.017, respectively). When comparing between visual conditions, stability score was significantly higher during eyes-closed compared to eyes-opened situations for SACH and ESAR foot (eyes-closed vs opened; SACH OSI: 3.43 vs 1.71, p = 0.018 and MLSI: 3.43 vs 1.71, p = 0.018; ESAR OSI: 3.58 vs 1.86, p = 0.043 and APSI: 1.80 vs 0.65, p = 0.027). Conclusions The results of this study suggested postural steadiness in below-knee amputees was not affected by the types of prosthetic foot during quiet upright standing, but was significantly affected when visual cues was absent. PMID:24597518

Effect of mat pilates exercise on postural alignment and body composition of middle-aged women

PubMed Central

Lee, Hyo Taek; Oh, Hyun Ok; Han, Hui Seung; Jin, Kwang Youn; Roh, Hyo Lyun

2016-01-01

[Purpose] This study attempted to examine whether Pilates is an effective exercise for improving the postural alignment and health of middle-aged women. [Subjects and Methods] The participants in this study were 36 middle-aged women (20 in the experimental group, 16 in the control group). The experimental group participated in Pilates exercise sessions three times a week for 12 weeks. Body alignment and composition measurements before and after applying the Pilates exercise program were performed with a body composition analyzer and a three-dimensional scanner. [Results] Postural alignment in the sagittal and horizontal planes was enhanced in the Pilates exercise group. Trunk alignment showed correlations with body fat and muscle mass. [Conclusion] The Pilates exercises are performed symmetrically and strengthen the deep muscles. Moreover, the results showed that muscle mass was correlated with trunk postural alignment and that the proper amount of muscle is critical in maintaining trunk postural alignment. PMID:27390396

Postural control as a function of time-of-day: influence of a prior strenuous running exercise or demanding sustained-attention task

PubMed Central

2013-01-01

Background The current experiment investigated the impact of two potential confounding variables on the postural balance in young participants: the induced-experimental activity prior to the static postural measurements and the well-documented time-of-day effects. We mainly hypothesized that an exhaustive exercise and a high attention-demanding task should result in alterations of postural control. Methods Ten participants performed three experimental sessions (differentiated by the activity – none, cognitive or physical – prior of the assessment of postural stability), separated by one day at least. Each session included postural balance assessments around 8 a.m., 12.00 p.m. and 5 p.m. ± 30 min. The physical and cognitive activities were performed only before the 12 o’clock assessment. The postural tests consisted of four conditions of quiet stance: stance on a firm surface with eyes open; stance on a firm surface with eyes closed; stance on a foam surface with eyes open and stance on a foam surface with eyes closed. Postural performance was assessed by various center of pressure (COP) parameters. Results Overall, the COP findings indicated activity-related postural impairment, with an increase in body sway in the most difficult conditions (with foam surface), especially when postural measurements are recorded just after the running exercise (physical session) or the psychomotor vigilance test (cognitive session). Conclusions Even if no specific influence of time-of-day on static postural control is demonstrated, our results clearly suggest that the activities prior to balance tests could be a potential confounding variable to be taken into account and controlled when assessing clinical postural balance. PMID:23452958

Two aspects of feedforward postural control: anticipatory postural adjustments and anticipatory synergy adjustments.

PubMed

Klous, Miriam; Mikulic, Pavle; Latash, Mark L

2011-05-01

We used the framework of the uncontrolled manifold hypothesis to explore the relations between anticipatory synergy adjustments (ASAs) and anticipatory postural adjustments (APAs) during feedforward control of vertical posture. ASAs represent a drop in the index of a multimuscle-mode synergy stabilizing the coordinate of the center of pressure in preparation to an action. ASAs reflect early changes of an index of covariation among variables reflecting muscle activation, whereas APAs reflect early changes in muscle activation levels averaged across trials. The assumed purpose of ASAs is to modify stability of performance variables, whereas the purpose of APAs is to change magnitudes of those variables. We hypothesized that ASAs would be seen before APAs and that this finding would be consistent with regard to the muscle-mode composition defined on the basis of different tasks and phases of action. Subjects performed a voluntary body sway task and a quick, bilateral shoulder flexion task under self-paced and reaction time conditions. Surface muscle activity of 12 leg and trunk muscles was analyzed to identify sets of 4 muscle modes for each task and for different phases within the shoulder flexion task. Variance components in the muscle-mode space and indexes of multimuscle-mode synergy stabilizing shift of the center of pressure were computed. ASAs were seen ∼ 100-150 ms prior to the task initiation, before APAs. The results were consistent with respect to different sets of muscle modes defined over the two tasks and different shoulder flexion phases. We conclude that the preparation for a self-triggered postural perturbation is associated with two types of anticipatory adjustments, ASAs and APAs. They reflect different feedforward processes within the hypothetical hierarchical control scheme, resulting in changes in patterns of covariation of elemental variables and in their patterns averaged across trials, respectively. The results show that synergies quantified using dissimilar sets of muscle modes show similar feedforward changes in preparation to action.

Sensorimotor integration in human postural control

NASA Technical Reports Server (NTRS)

Peterka, R. J.

2002-01-01

It is generally accepted that human bipedal upright stance is achieved by feedback mechanisms that generate an appropriate corrective torque based on body-sway motion detected primarily by visual, vestibular, and proprioceptive sensory systems. Because orientation information from the various senses is not always available (eyes closed) or accurate (compliant support surface), the postural control system must somehow adjust to maintain stance in a wide variety of environmental conditions. This is the sensorimotor integration problem that we investigated by evoking anterior-posterior (AP) body sway using pseudorandom rotation of the visual surround and/or support surface (amplitudes 0.5-8 degrees ) in both normal subjects and subjects with severe bilateral vestibular loss (VL). AP rotation of body center-of-mass (COM) was measured in response to six conditions offering different combinations of available sensory information. Stimulus-response data were analyzed using spectral analysis to compute transfer functions and coherence functions over a frequency range from 0.017 to 2.23 Hz. Stimulus-response data were quite linear for any given condition and amplitude. However, overall behavior in normal subjects was nonlinear because gain decreased and phase functions sometimes changed with increasing stimulus amplitude. "Sensory channel reweighting" could account for this nonlinear behavior with subjects showing increasing reliance on vestibular cues as stimulus amplitudes increased. VL subjects could not perform this reweighting, and their stimulus-response behavior remained quite linear. Transfer function curve fits based on a simple feedback control model provided estimates of postural stiffness, damping, and feedback time delay. There were only small changes in these parameters with increasing visual stimulus amplitude. However, stiffness increased as much as 60% with increasing support surface amplitude. To maintain postural stability and avoid resonant behavior, an increase in stiffness should be accompanied by a corresponding increase in damping. Increased damping was achieved primarily by decreasing the apparent time delay of feedback control rather than by changing the damping coefficient (i.e., corrective torque related to body-sway velocity). In normal subjects, stiffness and damping were highly correlated with body mass and moment of inertia, with stiffness always about 1/3 larger than necessary to resist the destabilizing torque due to gravity. The stiffness parameter in some VL subjects was larger compared with normal subjects, suggesting that they may use increased stiffness to help compensate for their loss. Overall results show that the simple act of standing quietly depends on a remarkably complex sensorimotor control system.

Testing Postural Stability: Are the Star Excursion Balance Test and Biodex Balance System Limits of Stability Tests Consistent?

PubMed

Glave, A Page; Didier, Jennifer J; Weatherwax, Jacqueline; Browning, Sarah J; Fiaud, Vanessa

2016-01-01

There are a variety of options to test postural stability; however many physical tests lack validity information. Two tests of postural stability - the Star Excursion Balance Test (SEBT) and Biodex Balance System Limits of Stability Test (LOS) - were examined to determine if similar components of balance were measured. Healthy adults (n=31) completed the LOS (levels 6 and 12) and SEBT (both legs). SEBT directions were offset by 180° to approximate LOS direction. Correlations and partial correlations controlling for height were analyzed. Correlations were significant for SEBT 45° and LOS back-left (6: r=-0.41; 12: r=-0.42; p<0.05), SEBT 90° and LOS 6 left (r=-0.51, p<0.05), SEBT 135(o) and LOS 6 front-left (r=-0.53, p<0.05), SEBT overall and LOS 6 overall (r=-0.43, p<0.05). Partial correlations were significant for SEBT 90° and LOS 6 left (rSEBT,LOS·H=-0.45, p<0.05) and SEBT 135° and LOS 6 front-left (rSEBT,LOS·H=-0.51, p<0.05), and SEBT overall and LOS 6 overall (rSEBT,LOS·H=-0.37, p<0.05). These findings indicate the tests seem to assess different components of balance. Research is needed to determine and define what specific components of balance are being assessed. Care must be taken when choosing balance tests to best match the test to the purpose of testing (fall risk, athletic performance, etc.). Copyright © 2015 Elsevier B.V. All rights reserved.

Static postural stability in women with stress urinary incontinence: Effects of vision and bladder filling.

PubMed

Chmielewska, Daria; Stania, Magdalena; Słomka, Kajetan; Błaszczak, Edward; Taradaj, Jakub; Dolibog, Patrycja; Juras, Grzegorz

2017-11-01

This case-control study was designed to compare static postural stability between women with stress urinary incontinence and continent women and it was hypothesized that women with incontinence aged around 50 years also have balance disorders. Eighteen women with incontinence and twelve women without incontinence aged 50-55 years participated in two 60-s trials of each of four different testing conditions: eyes open/full bladder, eyes open/empty bladder, eyes closed/full bladder, eyes closed/empty bladder. The center of foot pressure (COP): sway range, root mean square, velocity (in the antero-posterior and medio-lateral directions), and COP area were recorded. The stabilograms were decomposed into rambling and trembling components. The groups of women with and without incontinence differed during the full bladder condition in antero-posterior COP sway range, COP area, and rambling trajectory (range in the antero-posterior and medio-lateral directions, root mean square in the antero-posterior and medio-lateral directions and velocity in the antero-posterior direction). The women with incontinence had more difficulty controlling their postural balance than continent women while standing with a full bladder. Therefore, developing therapeutic management focused on strengthening the women's core muscles and improving their postural balance seems advisable. © 2017 Wiley Periodicals, Inc.

Feasibility and reliability of a virtual reality oculus platform to measure sensory integration for postural control in young adults.

PubMed

Lubetzky, Anat V; Kary, Erinn E; Harel, Daphna; Hujsak, Bryan; Perlin, Ken

2018-01-24

Using Unity for the Oculus Development-Kit 2, we have developed an affordable, portable virtual reality platform that targets the visuomotor domain, a missing link in current clinical assessments of postural control. Here, we describe the design and technical development as well as report its feasibility with regards to cybersickness and test-retest reliability in healthy young adults. Our virtual reality paradigm includes two functional scenes ('City' and 'Park') and four moving dots scenes. Twenty-one healthy young adults were tested twice, one to two weeks apart. They completed a simulator sickness questionnaire several times per session. Their postural sway response was recorded from a forceplate underneath their feet while standing on the floor, stability trainers, or a Both Sides Up (BOSU) ball. Sample entropy, postural displacement, velocity, and excursion were calculated and compared between sessions given the visual and surface conditions. Participants reported slight-to-moderate transient side effects. Intra-Class Correlation values mostly ranged from 0.5 to 0.7 for displacement and velocity, were above 0.5 (stability trainer conditions) and above 0.4 (floor mediolateral conditions) for sample entropy, and minimal for excursion. Our novel portable VR platform was found to be feasible and reliable in healthy young adults.

The effect of cap lamp lighting on postural control and stability

PubMed Central

Sammarco, John J.; Pollard, Jonisha P.; Porter, William L.; Dempsey, Patrick G.; Moore, Caitlin T.

2015-01-01

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are conducting mine illumination research with the objective of improving miner safety. Slips, trips, and falls (STFs) are the second leading accident class (18.1%, n = 2,374) of nonfatal lost-time injuries at underground mines (MSHA, 2005–2009). Factors contributing to STFs include recognition of hazards as well as postural balance and age. Improved lighting may enable better hazard recognition and reduce the impact of postural balance and age. Previous research has shown that cap lamp technology that used light-emitting diodes (LEDs) has improved hazard detection. This study was an initial investigation to determine if cap lamp lighting significantly influences measures of static postural stability (displacement and velocity of center of pressure). Results of this investigation showed no significant differences in the balance measures of interest between cap lamps tested. However, balance was shown to significantly decline (p < 0.05) when tested in an underground coal mine compared to the laboratory testing condition. Relevance to industry: Underground coal mine workers wear cap lamps on their hard hats as their primary light source to illuminate nearby areas where their vision is directed. Proper illumination may improve miner safety by improving their STF hazard recognition and balance. PMID:26472917

Imbalance in Multiple Sclerosis: A Result of Slowed Spinal Somatosensory Conduction

PubMed Central

Cameron, Michelle H.; Horak, Fay B.; Herndon, Robert R.; Bourdette, Dennis

2009-01-01

Balance problems and falls are common in people with multiple sclerosis (MS) but their cause and nature are not well understood. It is known that MS affects many areas of the central nervous system that can impact postural responses to maintain balance, including the cerebellum and the spinal cord. Cerebellar balance disorders are associated with normal latencies but reduced scaling of postural responses. We therefore examined the latency and scaling of automatic postural responses, and their relationship to somatosensory evoked potentials (SSEPs), in 10 people with MS and imbalance and 10 age-, sex-matched, healthy controls. The latency and scaling of postural responses to backward surface translations of 5 different velocities and amplitudes, and the latency of spinal and supraspinal somatosensory conduction, were examined. Subjects with MS had large, but very delayed automatic postural response latencies compared to controls (161ms ± 31 vs 102 ± 21, p < 0.01) and these postural response latencies correlated with the latencies of their spinal SSEPs (r=0.73, p< 0.01). Subjects with MS also had normal or excessive scaling of postural response amplitude to perturbation velocity and amplitude. Longer latency postural responses were associated with less velocity scaling and more amplitude scaling. Balance deficits in people with MS appear to be caused by slowed spinal somatosensory conduction and not by cerebellar involvement. People with MS appear to compensate for their slowed spinal somatosensory conduction by increasing the amplitude scaling and the magnitude of their postural responses. PMID:18570015

Postural strategies assessed with inertial sensors in healthy and parkinsonian subjects.

PubMed

Baston, Chiara; Mancini, Martina; Schoneburg, Bernadette; Horak, Fay; Rocchi, Laura

2014-01-01

The present study introduces a novel instrumented method to characterize postural movement strategies to maintain balance during stance (ankle and hip strategy), by means of inertial sensors, positioned on the legs and on the trunk. We evaluated postural strategies in subjects with 2 types of Parkinsonism: idiopathic Parkinson's disease (PD) and Progressive Supranuclear Palsy (PSP), and in age-matched control subjects standing under perturbed conditions implemented by the Sensory Organization Test (SOT). Coordination between the upper and lower segments of the body during postural sway was measured using a covariance index over time, by a sliding-window algorithm. Afterwards, a postural strategy index was computed. We also measured the amount of postural sway, as adjunctive information to characterize balance, by the root mean square of the horizontal trunk acceleration signal (RMS). showed that control subjects were able to change their postural strategy, whilst PSP and PD subjects persisted in use of an ankle strategy in all conditions. PD subjects had RMS values similar to control subjects even without changing postural strategy appropriately, whereas PSP subjects showed much larger RMS values than controls, resulting in several falls during the most challenging SOT conditions (5 and 6). Results are in accordance with the corresponding clinical literature describing postural behavior in the same kind of subjects. The proposed strategy index, based on the use of inertial sensors on the upper and lower body segments, is a promising and unobtrusive tool to characterize postural strategies performed to attain balance. Copyright © 2014 Elsevier B.V. All rights reserved.

Stroke Volume During Orthostatic Challenge: Comparison of Two Non-Invasive Methods

DTIC Science & Technology

2005-10-01

transition in posture from supine to HUT, a rapid me- chanical redistribution of blood from the central circu- lation toward the lower extremities...resting 12-lead ECG and clinical orthostatic exam ( supine /seated/ standing consecutive BP mea- surements) were obtained on each of the potential sub...during an orthostatic challenge has been reported elsewhere (4). Subjects maintained a supine posture for 30 min prior to the start of data collection

Orthostatic Intolerance in Older Persons: Etiology and Countermeasures

PubMed Central

Goswami, Nandu; Blaber, Andrew P.; Hinghofer-Szalkay, Helmut; Montani, Jean-Pierre

2017-01-01

Orthostatic challenge produced by upright posture may lead to syncope if the cardiovascular system is unable to maintain adequate brain perfusion. This review outlines orthostatic intolerance related to the aging process, long-term bedrest confinement, drugs, and disease. Aging-associated illness or injury due to falls often leads to hospitalization. Older patients spend up to 83% of hospital admission lying in bed and thus the consequences of bedrest confinement such as physiological deconditioning, functional decline, and orthostatic intolerance represent a central challenge in the care of the vulnerable older population. This review examines current scientific knowledge regarding orthostatic intolerance and how it comes about and provides a framework for understanding of (patho-) physiological concepts of cardiovascular (in-) stability in ambulatory and bedrest confined senior citizens as well as in individuals with disease conditions [e.g., orthostatic intolerance in patients with diabetes mellitus, multiple sclerosis, Parkinson's, spinal cord injury (SCI)] or those on multiple medications (polypharmacy). Understanding these aspects, along with cardio-postural interactions, is particularly important as blood pressure destabilization leading to orthostatic intolerance affects 3–4% of the general population, and in 4 out of 10 cases the exact cause remains elusive. Reviewed also are countermeasures to orthostatic intolerance such as exercise, water drinking, mental arithmetic, cognitive training, and respiration training in SCI patients. We speculate that optimally applied countermeasures such as mental challenge maintain sympathetic activity, and improve venous return, stroke volume, and consequently, blood pressure during upright standing. Finally, this paper emphasizes the importance of an active life style in old age and why early re-mobilization following bedrest confinement or bedrest is crucial in preventing orthostatic intolerance, falls and falls-related injuries in older persons. PMID:29163185

Management of postural sensory conflict and dynamic balance control in late-stage Parkinson's disease.

PubMed

Colnat-Coulbois, S; Gauchard, G C; Maillard, L; Barroche, G; Vespignani, H; Auque, J; Perrin, P P

2011-10-13

Parkinson's disease (PD) is known to affect postural control, especially in situations needing a change in balance strategy or when a concurrent task is simultaneously performed. However, few studies assessing postural control in patients with PD included homogeneous population in late stage of the disease. Thus, this study aimed to analyse postural control and strategies in a homogeneous population of patients with idiopathic advanced (late-stage) PD, and to determine the contribution of peripheral inputs in simple and more complex postural tasks, such as sensory conflicting and dynamic tasks. Twenty-four subjects with advanced PD (duration: median (M)=11.0 years, interquartile range (IQR)=4.3 years; Unified Parkinson's Disease Rating Scale (UPDRS): M "on-dopa"=13.5, IQR=7.8; UPDRS: M "off-dopa"=48.5, IQR=16.8; Hoehn and Yahr stage IV in all patients) and 48 age-matched healthy controls underwent static (SPT) and dynamic posturographic (DPT) tests and a sensory organization test (SOT). In SPT, patients with PD showed reduced postural control precision with increased oscillations in both anterior-posterior and medial-lateral planes. In SOT, patients with PD displayed reduced postural performances especially in situations in which visual and vestibular cues became predominant to organize balance control, as was the ability to manage balance in situations for which visual or proprioceptive inputs are disrupted. In DPT, postural restabilization strategies were often inefficient to maintain equilibrium resulting in falls. Postural strategies were often precarious, postural regulation involving more hip joint than ankle joint in patients with advanced PD than in controls. Difficulties in managing complex postural situations, such as sensory conflicting and dynamic situations might reflect an inadequate sensory organization suggesting impairment in central information processing. Copyright © 2011. Published by Elsevier Ltd.

Posture and equilibrium in orthopedic and rheumatologic diseases.

PubMed

Missaoui, B; Portero, P; Bendaya, S; Hanktie, O; Thoumie, P

2008-12-01

Posture and balance may be affected in many spine or lower-limb disorders. An extensive evaluation including clinical tests and movement analysis techniques may be necessary to characterize how rheumatologic or orthopedic diseases are related to static or dynamic changes in postural control. In lower limbs, unbalance may be related to a decreased stability following arthrosis or ligament injuries at knee or ankle levels, while hip lesions appear less associated with such troubles. Spinal diseases at cervical level are frequently associated with postural changes and impaired balance control, related to the major role of sensory inputs during stance and gait. At lower levels, changes are noticed in major scoliosis and may be related to pain intensity in patients with chronic low-back pain. Whatever the initial lesion and the affected level, improvement in clinical or instrumental tests following rehabilitation or brace wearing provides argument for a close relationship between rheumatologic or orthopedic diseases and related impairments in posture and balance control.

The contribution of postural balance analysis in older adult fallers: A narrative review.

PubMed

Pizzigalli, L; Micheletti Cremasco, M; Mulasso, A; Rainoldi, A

2016-04-01

Falls are a serious health problem for older adults. Several studies have identified the decline of postural balance as one of the main risk factors for falls. Contrary to what may be believed, the capability of force platform measurements to predict falls remains uncertain. The focus of this narrative review is the identification of postural characteristics of older adults at risk of falling using both static and dynamic postural balance assessments. The literature analysis was conducted on Medline/PubMed. The search ended in May 2015. Centre of pressure (CoP) path length, CoP velocity and sway in medial lateral and anterior-posterior are the variables that distinguish older adult fallers from non-fallers. Recommendations to medical personnel on how to provide efficient balance training for older adults are offered, discussing the relevance and limitations of postural stability on static and dynamic board in falling risk prevention. Copyright © 2015 Elsevier Ltd. All rights reserved.

The postural control can be optimized by the first movement initiation condition encountered when submitted to muscle fatigue.

PubMed

Monjo, Florian; Forestier, Nicolas

2017-08-01

We investigated whether and how the movement initiation condition (IC) encountered during the early movements performed following focal muscle fatigue affects the postural control of discrete ballistic movements. For this purpose, subjects performed shoulder flexions in a standing posture at maximal velocity under two movement IC, i.e., in self-paced conditions and submitted to a Stroop-like task in which participants had to trigger fast shoulder flexions at the presentation of incongruent colors. Shoulder flexion kinematics, surface muscle activity of focal and postural muscles as well as center-of-pressure kinematics were recorded. The initial IC and the order in which subjects were submitted to these two conditions were varied within two separate experimental sessions. IC schedule was repeated before and after fatigue protocols involving shoulder flexors. The aim of this fatigue procedure was to affect acceleration-generating capacities of focal muscles. In such conditions, the postural muscle activity preceding and accompanying movement execution is expected to decrease. Following fatigue, when subjects initially moved in self-paced conditions, postural muscle activity decreased and scaled to the lower focal peak acceleration. This postural strategy then transferred to the Stroop-like task. In contrast, when subjects initially moved submitted to the Stroop-like task, postural muscle activity did not decrease and this transferred to self-paced movements. Regarding the center-of-pressure peak velocity, which is indicative of the efficiency of the postural actions generated in stabilizing posture, no difference appeared between the two sessions post-fatigue. This highlights an optimization of the postural actions when subjects first moved in self-paced conditions, smaller postural muscle activation levels resulting in similar postural consequences. In conclusion, the level of neuromuscular activity associated with the postural control is affected and can be optimized by the initial movement IC experienced post-fatigue. Beyond the fundamental contributions arising from these results, we point out potential applications for trainers and sports instructors. Copyright © 2017 Elsevier B.V. All rights reserved.

Electromyography of wrist and finger flexor muscles in olive baboons (Papio anubis).

PubMed

Patel, Biren A; Larson, Susan G; Stern, Jack T

2012-01-01

Some non-human primates use digitigrade hand postures when walking slowly on the ground. As a component of an extended limb, a digitigrade posture can help minimize wrist joint moments thereby requiring little force production directly from wrist flexors (and/or from the assistance of finger flexors) to maintain limb posture. As a consequence, less active muscle volume would be required from these anti-gravity muscles and overall metabolic costs associated with locomotion could be reduced. To investigate whether the use of digitigrade hand postures during walking in primates entails minimal use of anti-gravity muscles, this study examined electromyography (EMG) patterns in both the wrist and finger flexor muscles in facultatively digitigrade olive baboons (Papio anubis) across a range of speeds. The results demonstrate that baboons can adopt a digitigrade hand posture when standing and moving at slow speeds without requiring substantial EMG activity from distal anti-gravity muscles. Higher speed locomotion, however, entails increasing EMG activity and is accompanied by a dynamic shift to a more palmigrade-like limb posture. Thus, the ability to adopt a digitigrade hand posture by monkeys is an adaptation for ground living, but it was never co-opted for fast locomotion. Rather, digitigrady in primates appears to be related to energetic efficiency for walking long distances.

Invariant density analysis: modeling and analysis of the postural control system using Markov chains.

PubMed

Hur, Pilwon; Shorter, K Alex; Mehta, Prashant G; Hsiao-Wecksler, Elizabeth T

2012-04-01

In this paper, a novel analysis technique, invariant density analysis (IDA), is introduced. IDA quantifies steady-state behavior of the postural control system using center of pressure (COP) data collected during quiet standing. IDA relies on the analysis of a reduced-order finite Markov model to characterize stochastic behavior observed during postural sway. Five IDA parameters characterize the model and offer physiological insight into the long-term dynamical behavior of the postural control system. Two studies were performed to demonstrate the efficacy of IDA. Study 1 showed that multiple short trials can be concatenated to create a dataset suitable for IDA. Study 2 demonstrated that IDA was effective at distinguishing age-related differences in postural control behavior between young, middle-aged, and older adults. These results suggest that the postural control system of young adults converges more quickly to their steady-state behavior while maintaining COP nearer an overall centroid than either the middle-aged or older adults. Additionally, larger entropy values for older adults indicate that their COP follows a more stochastic path, while smaller entropy values for young adults indicate a more deterministic path. These results illustrate the potential of IDA as a quantitative tool for the assessment of the quiet-standing postural control system.

A method to quantify the "cone of economy".

PubMed

Haddas, Ram; Lieberman, Isador H

2018-05-01

A non-randomized, prospective, concurrent control cohort study. The purpose of this study is to develop and evaluate a method to quantify the dimensions of the cone of economy (COE) and the energy expenditure associated with maintaining a balanced posture within the COE, scoliosis patients and compare them to matched non-scoliotic controls in a group of adult degenerative. Balance is defined as the ability of the human body to maintain its center of mass (COM) within the base of support with minimal postural sway. The cone of economy refers to the stable region of upright standing posture. The underlying assumption is that deviating outside one's individual cone challenges the balance mechanisms. Adult degenerative scoliosis (ADS) patients exhibit a variety of postural changes within their COE, involving the spine, pelvis and lower extremities, in their effort to compensate for the altered posture. Ten ADS patients and ten non-scoliotic volunteers performed a series of functional balance tests. The dimensions of the COE and the energy expenditure related to maintaining balance within the COE were measured using a human motion video capture system and dynamic surface electromyography. ADS patients presented more COM sway in the sagittal (ADS: 1.59 cm vs. H: 0.61 cm; p = 0.049) and coronal (ADS: 2.84 cm vs. H: 1.72 cm; p = 0.046) directions in comparison to the non-scoliotic control. ADS patients presented with more COM (ADS: 33.30 cm vs. H: 19.13 cm; p = 0.039) and head (ADS: 31.06 cm vs. H: 19.13 cm; p = 0.013) displacements in comparison to the non-scoliotic controls. Scoliosis patients expended more muscle activity to maintain static standing, as manifest by increased muscle activity in their erector spinae (ADS: 37.16 mV vs. H: 20.31 mV; p = 0.050), and gluteus maximus (ADS: 33.12 mV vs. H: 12.09 mV; p = 0.001) muscles. We were able to develop and evaluate a method that quantifies the COE boundaries, COM displacement, and amount of sway within the COE along with the energy expenditure for a specific patient. This method of COE measurement will enable spine care practitioners to objectively evaluate their patients in an effort to determine the most appropriate treatment options, and in objectively documenting the effectiveness of their intervention.

[Relationship between unipedal stance test score and center of pressure velocity in elderly].

PubMed

Rodrigo Antonio, Guzmán; Rony, Silvestre; Francisco Aniceto, Rodríguez; David Andrés, Arriagada; Pablo Andrés, Ortega

2011-01-01

Frequent falls are one of the most important health problems in the elderly population. The unipedal stance test (UPST), asses postural stability and is used in fall risk measures. Despite this, there is little information about its relationship with posturographic parameters (PP) that characterizes postural stability. Center of pressure velocity (CoPV) is one of the best PP that describes postural stability. The aim of this study was to analyze the relation between UST score and CoPV in elderly population. A sample of 38 healthy elderly subjects where divided in two groups according to their UPST score, low performance (LP, n=11) and high performance (HP, n=27). The correlation between UPST score and COP mean velocity (CoPmV), recorded from a posturographic test, was analyzed between both groups. An inverse correlation between UPST score and CoPmV was found in both groups. However, this was higher in the LP group (r=-0.69, P=.02) compared to the HP (r=-0.39, P=.04). Based on the results of this investigation, it may be concluded that the achievement on UPST has an inverse relationship with CoPmV, especially in subjects with low performance in the UPST. Copyright © 2010 SEGG. Published by Elsevier Espana. All rights reserved.

Resistance Training Exercise Program for Intervention to Enhance Gait Function in Elderly Chronically Ill Patients: Multivariate Multiscale Entropy for Center of Pressure Signal Analysis

PubMed Central

Jiang, Bernard C.

2014-01-01

Falls are unpredictable accidents, and the resulting injuries can be serious in the elderly, particularly those with chronic diseases. Regular exercise is recommended to prevent and treat hypertension and other chronic diseases by reducing clinical blood pressure. The “complexity index” (CI), based on multiscale entropy (MSE) algorithm, has been applied in recent studies to show a person's adaptability to intrinsic and external perturbations and widely used measure of postural sway or stability. The multivariate multiscale entropy (MMSE) was advanced algorithm used to calculate the complexity index (CI) values of the center of pressure (COP) data. In this study, we applied the MSE & MMSE to analyze gait function of 24 elderly, chronically ill patients (44% female; 56% male; mean age, 67.56 ± 10.70 years) with either cardiovascular disease, diabetes mellitus, or osteoporosis. After a 12-week training program, postural stability measurements showed significant improvements. Our results showed beneficial effects of resistance training, which can be used to improve postural stability in the elderly and indicated that MMSE algorithms to calculate CI of the COP data were superior to the multiscale entropy (MSE) algorithm to identify the sense of balance in the elderly. PMID:25295070

Compensatory mechanisms of balance to the scaling of arm-swing frequency.

PubMed

Ko, Ji Hyun; Wang, Zheng; Challis, John H; Newell, Karl M

2015-11-05

The present study investigated the contribution of the Hof (2007) mechanism 1 (M1-moving the center of pressure (COP) with respect to the vertical projection of the center of mass (COMTotal)); and mechanism 2 (M2-rotating the trunk and upper limbs around the COMTotal) to postural control and the stability of COP-COMTotal cophase as a function of lateral arm-swing frequency. Young adults were instructed to stand still on a force platform while alternating their arm swinging from above the head to the side of their thigh to create perturbations to postural control. Scaling the frequency of arm-swing (random step changes of 0.2 Hz within a bandwidth of 0.2 to 1.6 Hz) increased the SD of COP but decreased the SD of COMTotal. Increments in arm-swing frequency induced a progressive increase in M1 and decrease in M2 in terms of their relative contribution to postural stability. The cophase between COP and COMTotal became more tightly in-phase over increments of arm-swing frequency. These findings show an adaptive compensatory role of M1 and M2 within the stability of COP-COMTotal coupling in the regulation of human balance control. Copyright © 2015 Elsevier Ltd. All rights reserved.

The role of cross-sectional geometry, curvature, and limb posture in maintaining equal safety factors: a computed tomography study.

PubMed

Brassey, Charlotte A; Kitchener, Andrew C; Withers, Philip J; Manning, Phillip L; Sellers, William I

2013-03-01

The limb bones of an elephant are considered to experience similar peak locomotory stresses as a shrew. "Safety factors" are maintained across the entire range of body masses through a combination of robusticity of long bones, postural variation, and modification of gait. The relative contributions of these variables remain uncertain. To test the role of shape change, we undertook X-ray tomographic scans of the leg bones of 60 species of mammals and birds, and extracted geometric properties. The maximum resistible forces the bones could withstand before yield under compressive, bending, and torsional loads were calculated using standard engineering equations incorporating curvature. Positive allometric scaling of cross-sectional properties with body mass was insufficient to prevent negative allometry of bending (F(b) ) and torsional maximum force (F(t) ) (and hence decreasing safety factors) in mammalian (femur F(b) ∞M(b) (0.76) , F(t) ∞M(b) (0.80) ; tibia F(b) ∞M(b) (0.80) , F(t) ∞M(b) (0.76) ) and avian hindlimbs (tibiotarsus F(b) ∞M(b) (0.88) , F(t) ∞M(b) (0.89) ) with the exception of avian femoral F(b) and F(t) . The minimum angle from horizontal a bone must be held while maintaining a given safety factor under combined compressive and bending loads increases with M(b) , with the exception of the avian femur. Postural erectness is shown as an effective means of achieving stress similarity in mammals. The scaling behavior of the avian femur is discussed in light of unusual posture and kinematics. Copyright © 2013 Wiley Periodicals, Inc.

The relationship between hippocampal volume and static postural sway: results from the GAIT study.

PubMed

Beauchet, Olivier; Barden, John; Liu-Ambrose, Teresa; Chester, Victoria L; Szturm, Tony; Allali, Gilles

2016-02-01

The role of the hippocampus in postural control, in particular in maintaining upright stance, has not been fully examined in normal aging. This study aims to examine the association of postural sway with hippocampal volume while maintaining upright stance in healthy older individuals. Seventy healthy individuals (mean age 69.7 ± 3.4 years; 41.4 % women) were recruited in this study based on cross-sectional design. Hippocampal volume (quantified from a three-dimensional T1-weighted MRI using semi-automated software), three center of pressure (COP) motion parameters (sway area, path length of anterior-posterior (AP) and medial-lateral (ML) displacement) while maintaining upright stance (eyes open and closed), and the relative difference between open and closed eye conditions were used as outcome measures. Age, sex, body mass index, lower limb proprioception, distance vision, 15-item geriatric depression scale score, total cranial volume, and white matter abnormalities were used as covariates. The sway area decreased from open to closed eye condition but this variation was non-significant (P = 0.244), whereas path length of AP and ML displacement increased significantly (P < 0.003). Increase in sway area from open to closed eyes was associated with greater hippocampal volume (β -18.21; P = 0.044), and a trend for an association of increase in path length of AP displacement (P = 0.075 for open eyes and P = 0.071 for closed eyes) with greater hippocampal volume was reported. The hippocampus is involved in upright postural control in normal aging, such that an increase in sway area of COP motion from open to closed eyes is associated with greater hippocampal volume in healthy older adults.

Physiological and Functional Alterations after Spaceflight and Bed Rest.

PubMed

Mulavara, Ajitkumar P; Peters, Brian T; Miller, Chris A; Kofman, Igor S; Reschke, Millard F; Taylor, Laura C; Lawrence, Emily L; Wood, Scott J; Laurie, Steven S; Lee, Stuart M C; Buxton, Roxanne E; May-Phillips, Tiffany R; Stenger, Michael B; Ploutz-Snyder, Lori L; Ryder, Jeffrey W; Feiveson, Alan H; Bloomberg, Jacob J

2018-04-03

Exposure to microgravity causes alterations in multiple physiological systems, potentially impacting the ability of astronauts to perform critical mission tasks. The goal of this study was to determine the effects of spaceflight on functional task performance and to identify the key physiological factors contributing to their deficits. A test battery comprised of 7 functional tests and 15 physiological measures was used to investigate the sensorimotor, cardiovascular and neuromuscular adaptations to spaceflight. Astronauts were tested before and after 6-month spaceflights. Subjects were also tested before and after 70 days of 6° head-down bed rest, a spaceflight analog, to examine the role of axial body unloading on the spaceflight results. These subjects included Control and Exercise groups to examine the effects of exercise during bed rest. Spaceflight subjects showed the greatest decrement in performance during functional tasks that required the greatest demand for dynamic control of postural equilibrium which was paralleled by similar decrements in sensorimotor tests that assessed postural and dynamic gait control. Other changes included reduced lower limb muscle performance and increased heart rate to maintain blood pressure. Exercise performed during bed rest prevented detrimental change in neuromuscular and cardiovascular function, however, both bed rest groups experienced functional and balance deficits similar to spaceflight subjects. Bed rest data indicates that body support unloading experienced during spaceflight contributes to postflight postural control dysfunction. Further, the bed rest results in the Exercise group of subjects confirm that resistance and aerobic exercises performed during spaceflight can play an integral role in maintaining neuromuscular and cardiovascular function, which can help in reducing decrements in functional performance. These results indicate that a countermeasure to mitigate postflight postural control dysfunction is required to maintain functional performance.

Muscle short-range stiffness can be used to estimate the endpoint stiffness of the human arm

PubMed Central

Hu, Xiao; Murray, Wendy M.

2011-01-01

The mechanical properties of the human arm are regulated to maintain stability across many tasks. The static mechanics of the arm can be characterized by estimates of endpoint stiffness, considered especially relevant for the maintenance of posture. At a fixed posture, endpoint stiffness can be regulated by changes in muscle activation, but which activation-dependent muscle properties contribute to this global measure of limb mechanics remains unclear. We evaluated the role of muscle properties in the regulation of endpoint stiffness by incorporating scalable models of muscle stiffness into a three-dimensional musculoskeletal model of the human arm. Two classes of muscle models were tested: one characterizing short-range stiffness and two estimating stiffness from the slope of the force-length curve. All models were compared with previously collected experimental data describing how endpoint stiffness varies with changes in voluntary force. Importantly, muscle properties were not fit to the experimental data but scaled only by the geometry of individual muscles in the model. We found that force-dependent variations in endpoint stiffness were accurately described by the short-range stiffness of active arm muscles. Over the wide range of evaluated arm postures and voluntary forces, the musculoskeletal model incorporating short-range stiffness accounted for 98 ± 2, 91 ± 4, and 82 ± 12% of the variance in stiffness orientation, shape, and area, respectively, across all simulated subjects. In contrast, estimates based on muscle force-length curves were less accurate in all measures, especially stiffness area. These results suggest that muscle short-range stiffness is a major contributor to endpoint stiffness of the human arm. Furthermore, the developed model provides an important tool for assessing how the nervous system may regulate endpoint stiffness via changes in muscle activation. PMID:21289133

Quantitative posturography in altered sensory conditions: a way to assess balance instability in patients with chronic whiplash injury.

PubMed

Madeleine, Pascal; Prietzel, Hanne; Svarrer, Heine; Arendt-Nielsen, Lars

2004-03-01

To quantify neck mobility and posture with and without various postural perturbations. A multivariable 2-group study with repeated measures and treatments. A human performance laboratory. Eleven patients with chronic whiplash injury (mean age, 33.3+/-6.7 y; weight, 73.4+/-11.4 kg; height, 173.3+/-7.2 cm) with a sex- and age-matched control group (mean age, 33.1+/-6.8 y; weight, 68+/-12.5 kg; height, 171.5+/-6.3 cm). Neck mobility and the effects of postural perturbations affecting the visual, vestibular, cutaneous, proprioceptive, and nociceptive systems were measured. Active range of motion, neck position sense, and postural activity. We found significantly reduced neck mobility and increased postural activity in the patient group compared with the control group. In patients, there was significantly greater postural activity with eyes closed, eyes open and speaking, and eyes closed with Achilles' tendons vibrations compared with eyes open with no vibrations. In the controls, there was no significant effect of experimental muscle pain on postural activity. Patients with chronic whiplash injury had a protective response to neck movement and different tuning, sequencing, and execution of the postural synergies probably because of excessive reliance on visual input despite a possible deficit and altered vestibular and/or proprioceptive activity. In healthy volunteers, the pain induced by a single bolus injection of hypertonic saline was probably too limited in intensity and spreading to decrease postural stability.

Inadequate interaction between open- and closed-loop postural control in phobic postural vertigo.

PubMed

Wuehr, M; Pradhan, C; Novozhilov, S; Krafczyk, S; Brandt, T; Jahn, K; Schniepp, R

2013-05-01

Phobic postural vertigo (PPV) is characterized by a subjective dizziness and postural imbalance. Changes in postural control strategy may cause the disturbed postural performance in PPV. A better understanding of the mechanisms behind this change in strategy is required to improve the diagnostic tools and therapeutic options for this prevalent disorder. Here we apply stabilogram diffusion analysis (SDA) to examine the characteristics and modes of interaction of open- and closed-loop processes that make up the postural control scheme in PPV. Twenty patients with PPV and 20 age-matched healthy controls were recorded on a stabilometer platform with eyes open and with eyes closed. Spatio-temporal changes of the center of pressure (CoP) displacement were analyzed by means of SDA and complementary CoP amplitude measures. (1) Open-loop control mechanisms in PPV were disturbed because of a higher diffusion activity (p < 0.001). (2) The interaction of open- and closed-loop processes was altered in that the sensory feedback threshold of the system was lowered (p = 0.010). These two changes were comparable to those observed in healthy subjects during more demanding balance conditions such as standing with eyes closed. These data indicate that subjective imbalance in PPV is associated with characteristic changes in the coordination of open- and closed-loop mechanisms of postural control. Patients with PPV use sensory feedback inadequately during undisturbed stance, and this impairs postural performance. These changes are compatible with higher levels of anti-gravity muscle activity and co-contraction during the conscious concentration on control of postural stability.

Relationship between Spectral Characteristics of Spontaneous Postural Sway and Motion Sickness Susceptibility.

PubMed

Laboissière, Rafael; Letievant, Jean-Charles; Ionescu, Eugen; Barraud, Pierre-Alain; Mazzuca, Michel; Cian, Corinne

2015-01-01

Motion sickness (MS) usually occurs for a narrow band of frequencies of the imposed oscillation. It happens that this frequency band is close to that which are spontaneously produced by postural sway during natural stance. This study examined the relationship between reported susceptibility to motion sickness and postural control. The hypothesis is that the level of MS can be inferred from the shape of the Power Spectral Density (PSD) profile of spontaneous sway, as measured by the displacement of the center of mass during stationary, upright stance. In Experiment 1, postural fluctuations while standing quietly were related to MS history for inertial motion. In Experiment 2, postural stability measures registered before the onset of a visual roll movement were related to MS symptoms following the visual stimulation. Study of spectral characteristics in postural control showed differences in the distribution of energy along the power spectrum of the antero-posterior sway signal. Participants with MS history provoked by exposure to inertial motion showed a stronger contribution of the high frequency components of the sway signal. When MS was visually triggered, sick participants showed more postural sway in the low frequency range. The results suggest that subject-specific PSD details may be a predictor of the MS level. Furthermore, the analysis of the sway frequency spectrum provided insight into the intersubject differences in the use of postural control subsystems. The relationship observed between MS susceptibility and spontaneous posture is discussed in terms of postural sensory weighting and in relation to the nature of the provocative stimulus.

Trunk postural adjustments: Medium-term reliability and correlation with changes of clinical outcomes following an 8-week lumbar stabilization exercise program.

PubMed

Boucher, Jean-Alexandre; Preuss, Richard; Henry, Sharon M; Nugent, Marilee; Larivière, Christian

2018-04-22

Low back pain (LBP) has been previously associated with delayed anticipatory postural adjustments (APAs) determined by trunk muscle activation. Lumbar stabilization exercise programs (LSEP) for patients with LBP may restore the trunk neuromuscular control of the lumbar spine, and normalize APAs. This exploratory study aimed at testing the reliability of EMG and kinematics-based postural adjustment measures over an 8-week interval, assessing their sensitivity to LBP status and treatment and examining their relationship with clinical outcomes. Muscle activation of 10 trunk muscles, using surface electromyography (EMG), and lumbar angular kinematics were recorded during a rapid arm-raising/lowering task. Patients with LBP were tested before and after an 8-week LSEP. Healthy controls receiving no treatment were assessed over the same interval to determine the reliability of the measures and act as a control group at baseline. Muscle activation onsets and reactive range of motion, range of velocities and accelerations were assessed for between group differences at baseline and pre- to post-treatment effects within patients with LBP using t-tests. Correlations between these dependent variables and the change of clinical outcomes (pain, disability) over treatment were also explored. Kinematic-based measures showed comparable reliability to EMG-based measures. Between-group differences were found in lumbar lateral flexion ROM at baseline (patients < controls). In the patients with LBP, lateral flexion velocity and acceleration significantly increased following the LSEP. Correlational analyses revealed that lumbar angular kinematics were more sensitive to changes in pain intensity following the LSEP compared to EMG measures. These findings are interpreted in from the perspective of guarding behaviors and lumbar stability hypotheses. Future clinical trials are needed to target patients with and without delayed APAs at baseline and to explore the sensitivity of different outcome measures related to APAs. Different tasks more challenging to postural stability may need to be explored to more effectively reveal APA dysfunction. Copyright © 2018. Published by Elsevier Ltd.

Effects of myofascial release techniques on pain, physical function, and postural stability in patients with fibromyalgia: a randomized controlled trial.

PubMed

Castro-Sánchez, Adelaida María; Matarán-Peñarrocha, Guillermo A; Arroyo-Morales, Manuel; Saavedra-Hernández, Manuel; Fernández-Sola, Cayetano; Moreno-Lorenzo, Carmen

2011-09-01

To determine the effect of myofascial release techniques on pain symptoms, postural stability and physical function in fibromyalgia syndrome. A randomized, placebo-controlled trial was undertaken. Eighty-six patients with fibromyalgia syndrome were randomly assigned to an experimental group and a placebo group. Patients received treatments for 20 weeks. The experimental group underwent 10 myofascial release modalities and the placebo group received sham short-wave and ultrasound electrotherapy. Outcome variables were number of tender points, pain, postural stability, physical function, clinical severity and global clinical assessment of improvement. Outcome measures were assessed before and immediately after, at six months and one year after the last session of the corresponding intervention. After 20 weeks of myofascial therapy, the experimental group showed a significant improvement (P  <  0.05) in painful tender points, McGill Pain Score (20.6 ± 6.3, P < 0.032), physical function (56.10 ± 17.3, P < 0.029), and clinical severity (5.08 ± 1.03, P < 0.039). At six months post intervention, the experimental group had a significantly lower mean number of painful points, pain score (8.25 ± 1.13, P < 0.048), physical function (58.60 ± 16.30, P < 0.049) and clinical severity (5.28 ± 0.97, P < 0.043). At one year post intervention, the only significant improvements were in painful points at second left rib and left gluteal muscle, affective dimension, number of days feeling good and clinical severity. The results suggest that myofascial release techniques can be a complementary therapy for pain symptoms, physical function and clinical severity but do not improve postural stability in patients with fibromyalgia syndrome.

Assessment of Relationships Between Joint Motion Quality and Postural Control in Patients With Chronic Ankle Joint Instability.

PubMed

Bączkowicz, Dawid; Falkowski, Krzysztof; Majorczyk, Edyta

2017-08-01

Study Design Controlled laboratory study, cross-sectional. Background Lateral ankle sprains are among the most common injuries encountered during athletic participation. Following the initial injury, there is an alarmingly high risk of reinjury and development of chronic ankle instability (CAI), which is dependent on a combination of factors, including sensorimotor deficits and changes in the biomechanical environment of the ankle joint. Objective To evaluate CAI-related disturbances in arthrokinematic motion quality and postural control and the relationships between them. Methods Sixty-three male subjects (31 with CAI and 32 healthy controls) were enrolled in the study. For arthrokinematic motion quality analysis, the vibroarthrographic signals were collected during ankle flexion/extension motion using an acceleration sensor and described by variability (variance of mean squares [VMS]), amplitude (mean of 4 maximal and 4 minimal values [R4]), and frequency (vibroarthrographic signal bands of 50 to 250 Hz [P1] and 250 to 450 Hz [P2]) parameters. Using the Biodex Balance System, single-leg dynamic balance was measured by overall, anteroposterior, and mediolateral stability indices. Results Values of vibroarthrographic parameters (VMS, R4, P1 and P2) were significantly higher in the CAI group than those in the control group (P<.01). Similar results were obtained for all postural control parameters (overall, anteroposterior, and mediolateral stability indices; P<.05). Moreover, correlations between the overall stability index and VMS, and P1 and P2, as well as between the anteroposterior stability index and P1 and P2, were observed in the CAI patient group, but not in controls. Conclusion In patients with CAI, deficits in both quality of ankle arthrokinematic motion and postural control were present. Therefore, physical therapy interventions focused on improving ankle neuromuscular control and arthrokinematic function are necessary in CAI patient care. J Orthop Sports Phys Ther 2017;47(8):570-577. Epub 4 Nov 2016. doi:10.2519/jospt.2017.6836.

Relations between postural stability, gait and falls in elderly persons--preliminary report.

PubMed

Baczkowicz, Dawid; Szczegielniak, Jan; Proszkowiec, Małgorzata

2008-01-01

Balance control in elderly patients is the area of interest of many researchers. The results of their studies suggest that the measurement of shifts in the centre of foot pressure on the support base (COP) can be used as a tool for identification of fall-prone persons. It is interesting whether there are any relations between functional status, gait, posture stability and the risk of falling. The aim of this study was to find the answer to this question. The study involved 20 patients (mean age 78.1+/-11.6). The functional status of the patients was evaluated according to the Barthel Index. Postural stability was assessed with the use of a Neurocom Balance Master platform. Three measurements were taken with visual feedback (eyes open-EO) and three without visual feedback (eyes closed-EC). Balance control was also evaluated with the Berg test and on the basis of the history of episodes of falling in the preceding six months. Gait was evaluated with the six-minute walking test. The parameters recorded by the force platform showed a significant relation to the values obtained in the Berg test (r=-0.60; p<0.001 for EO and r=-0.58; p<0.001 for EC). Similar trends were noted for the relation between EO and distance/velocity as well as functional status (r=-0.63 and -0.68; p<0.001). On the other hand the number of falls showed a significant relation only to the EO test (r=0.4; p<0.05). 1. An evaluation of balance control with a force platform and the Berg test produced convergent results. 2. The incidence of falls was connected with increased body sway. 3. The functional status of the patient and the balance control evaluation according to the Berg test failed to determine the risk of falling. 4. A relation was observed between postural stability, functional status and gait.

The effects of anxiety and external attentional focus on postural control in patients with Parkinson's disease

PubMed Central

Jazaeri, Seyede Zohreh; Azad, Akram; Mehdizadeh, Hajar; Habibi, Seyed Amirhassan; Mandehgary Najafabadi, Mahbubeh; Saberi, Zakieh Sadat; Rahimzadegan, Hawre; Moradi, Saeed; Behzadipour, Saeed; Parnianpour, Mohamad; Khalaf, Kinda

2018-01-01

Background Although anxiety is a common non-motor outcome of Parkinson's disease (PD) affecting 40% of patients, little attention has been paid so far to its effects on balance impairment and postural control. Improvement of postural control through focusing on the environment (i.e. external focus) has been reported, but the role of anxiety, as a confounding variable, remains unclear. Objectives This study aimed to investigate the influence of anxiety and attentional focus instruction on the standing postural control of PD patients. Methods Thirty-four patients with PD (17 with high anxiety (HA-PD) and 17 with low anxiety (LA-PD)), as well as 17 gender- and age-matched healthy control subjects (HC) participated in the study. Postural control was evaluated using a combination of two levels of postural difficulty (standing on a rigid force plate surface with open eyes (RO) and standing on a foam surface with open eyes (FO)), as well as three attentional focus instructions (internal, external and no focus). Results Only the HA-PD group demonstrated significant postural control impairment as compared to the control, as indicated by significantly greater postural sway measures. Moreover, external focus significantly reduced postural sway in all participants especially during the FO condition. Conclusion The results of the current study provide evidence that anxiety influences balance control and postural stability in patients with PD, particularly those with high levels of anxiety. The results also confirmed that external focus is a potential strategy that significantly improves the postural control of these patients. Further investigation of clinical applicability is warranted towards developing effective therapeutic and rehabilitative treatment plans. PMID:29390029