Subcortical Control of Precision Grip after Human Spinal Cord Injury

PubMed Central

Bunday, Karen L.; Tazoe, Toshiki; Rothwell, John C.

2014-01-01

The motor cortex and the corticospinal system contribute to the control of a precision grip between the thumb and index finger. The involvement of subcortical pathways during human precision grip remains unclear. Using noninvasive cortical and cervicomedullary stimulation, we examined motor evoked potentials (MEPs) and the activity in intracortical and subcortical pathways targeting an intrinsic hand muscle when grasping a small (6 mm) cylinder between the thumb and index finger and during index finger abduction in uninjured humans and in patients with subcortical damage due to incomplete cervical spinal cord injury (SCI). We demonstrate that cortical and cervicomedullary MEP size was reduced during precision grip compared with index finger abduction in uninjured humans, but was unchanged in SCI patients. Regardless of whether cortical and cervicomedullary stimulation was used, suppression of the MEP was only evident 1–3 ms after its onset. Long-term (∼5 years) use of the GABAb receptor agonist baclofen by SCI patients reduced MEP size during precision grip to similar levels as uninjured humans. Index finger sensory function correlated with MEP size during precision grip in SCI patients. Intracortical inhibition decreased during precision grip and spinal motoneuron excitability remained unchanged in all groups. Our results demonstrate that the control of precision grip in humans involves premotoneuronal subcortical mechanisms, likely disynaptic or polysynaptic spinal pathways that are lacking after SCI and restored by long-term use of baclofen. We propose that spinal GABAb-ergic interneuronal circuits, which are sensitive to baclofen, are part of the subcortical premotoneuronal network shaping corticospinal output during human precision grip. PMID:24849366

Fitts' Law in the Control of Isometric Grip Force With Naturalistic Targets.

PubMed

Thumser, Zachary C; Slifkin, Andrew B; Beckler, Dylan T; Marasco, Paul D

2018-01-01

Fitts' law models the relationship between amplitude, precision, and speed of rapid movements. It is widely used to quantify performance in pointing tasks, study human-computer interaction, and generally to understand perceptual-motor information processes, including research to model performance in isometric force production tasks. Applying Fitts' law to an isometric grip force task would allow for quantifying grasp performance in rehabilitative medicine and may aid research on prosthetic control and design. We examined whether Fitts' law would hold when participants attempted to accurately produce their intended force output while grasping a manipulandum when presented with images of various everyday objects (we termed this the implicit task). Although our main interest was the implicit task, to benchmark it and establish validity, we examined performance against a more standard visual feedback condition via a digital force-feedback meter on a video monitor (explicit task). Next, we progressed from visual force feedback with force meter targets to the same targets without visual force feedback (operating largely on feedforward control with tactile feedback). This provided an opportunity to see if Fitts' law would hold without vision, and allowed us to progress toward the more naturalistic implicit task (which does not include visual feedback). Finally, we changed the nature of the targets from requiring explicit force values presented as arrows on a force-feedback meter (explicit targets) to the more naturalistic and intuitive target forces implied by images of objects (implicit targets). With visual force feedback the relation between task difficulty and the time to produce the target grip force was predicted by Fitts' law (average r 2 = 0.82). Without vision, average grip force scaled accurately although force variability was insensitive to the target presented. In contrast, images of everyday objects generated more reliable grip forces without the visualized force meter. In sum, population means were well-described by Fitts' law for explicit targets with vision ( r 2 = 0.96) and implicit targets ( r 2 = 0.89), but not as well-described for explicit targets without vision ( r 2 = 0.54). Implicit targets should provide a realistic see-object-squeeze-object test using Fitts' law to quantify the relative speed-accuracy relationship of any given grasper.

Force related hemodynamic responses during execution and imagery of a hand grip task: A functional near infrared spectroscopy study.

PubMed

Wriessnegger, Selina C; Kirchmeyr, Daniela; Bauernfeind, Günther; Müller-Putz, Gernot R

2017-10-01

We examined force related hemodynamic changes during the performance of a motor execution (ME) and motor imagery (MI) task by means of multichannel functional near infrared spectroscopy (fNIRS). The hemodynamic responses of fourteen healthy participants were measured while they performed a hand grip execution or imagery task with low and high grip forces. We found an overall higher increase of [oxy-Hb] concentration changes during ME for both grip forces but with a delayed peak maximum for the lower grip force. During the MI task with lower grip force, the [oxy-Hb] level increases are stronger compared to the MI with higher grip force. The facilitation in performing MI with higher grip strength might thus indicate less inhibition of the actual motor act which could also explain the later increase onset of [oxy-Hb] in the ME task with the lower grip force. Our results suggest that execution and imagery of a hand grip task with high and low grip forces, leads to different cortical activation patterns. Since impaired control of grip forces during object manipulation in particular is one aspect of fine motor control deficits after stroke, our study will contribute to future rehabilitation programs enhancing patient's grip force control. Copyright © 2017 Elsevier Inc. All rights reserved.

Somato-Motor Haptic Processing in Posterior Inner Perisylvian Region (SII/pIC) of the Macaque Monkey

PubMed Central

Ishida, Hiroaki; Fornia, Luca; Grandi, Laura Clara; Umiltà, Maria Alessandra; Gallese, Vittorio

2013-01-01

The posterior inner perisylvian region including the secondary somatosensory cortex (area SII) and the adjacent region of posterior insular cortex (pIC) has been implicated in haptic processing by integrating somato-motor information during hand-manipulation, both in humans and in non-human primates. However, motor-related properties during hand-manipulation are still largely unknown. To investigate a motor-related activity in the hand region of SII/pIC, two macaque monkeys were trained to perform a hand-manipulation task, requiring 3 different grip types (precision grip, finger exploration, side grip) both in light and in dark conditions. Our results showed that 70% (n = 33/48) of task related neurons within SII/pIC were only activated during monkeys’ active hand-manipulation. Of those 33 neurons, 15 (45%) began to discharge before hand-target contact, while the remaining neurons were tonically active after contact. Thirty-percent (n = 15/48) of studied neurons responded to both passive somatosensory stimulation and to the motor task. A consistent percentage of task-related neurons in SII/pIC was selectively activated during finger exploration (FE) and precision grasping (PG) execution, suggesting they play a pivotal role in control skilled finger movements. Furthermore, hand-manipulation-related neurons also responded when visual feedback was absent in the dark. Altogether, our results suggest that somato-motor neurons in SII/pIC likely contribute to haptic processing from the initial to the final phase of grasping and object manipulation. Such motor-related activity could also provide the somato-motor binding principle enabling the translation of diachronic somatosensory inputs into a coherent image of the explored object. PMID:23936121

Getting a grip: different actions and visual guidance of the thumb and finger in precision grasping.

PubMed

Melmoth, Dean R; Grant, Simon

2012-10-01

We manipulated the visual information available for grasping to examine what is visually guided when subjects get a precision grip on a common class of object (upright cylinders). In Experiment 1, objects (2 sizes) were placed at different eccentricities to vary the relative proximity to the participant's (n = 6) body of their thumb and finger contact positions in the final grip orientations, with vision available throughout or only for movement programming. Thumb trajectories were straighter and less variable than finger paths, and the thumb normally made initial contact with the objects at a relatively invariant landing site, but consistent thumb first-contacts were disrupted without visual guidance. Finger deviations were more affected by the object's properties and increased when vision was unavailable after movement onset. In Experiment 2, participants (n = 12) grasped 'glow-in-the-dark' objects wearing different luminous gloves in which the whole hand was visible or the thumb or the index finger was selectively occluded. Grip closure times were prolonged and thumb first-contacts disrupted when subjects could not see their thumb, whereas occluding the finger resulted in wider grips at contact because this digit remained distant from the object. Results were together consistent with visual feedback guiding the thumb in the period just prior to contacting the object, with the finger more involved in opening the grip and avoiding collision with the opposite contact surface. As people can overtly fixate only one object contact point at a time, we suggest that selecting one digit for online guidance represents an optimal strategy for initial grip placement. Other grasping tasks, in which the finger appears to be used for this purpose, are discussed.

Grip force and force sharing in two different manipulation tasks with bottles.

PubMed

Cepriá-Bernal, Javier; Pérez-González, Antonio; Mora, Marta C; Sancho-Bru, Joaquín L

2017-07-01

Grip force and force sharing during two activities of daily living were analysed experimentally in 10 right-handed subjects. Four different bottles, filled to two different levels, were manipulated for two tasks: transporting and pouring. Each test subject's hand was instrumented with eight thin wearable force sensors. The grip force and force sharing were significantly different for each bottle model. Increasing the filling level resulted in an increase in grip force, but the ratio of grip force to load force was higher for lighter loads. The task influenced the force sharing but not the mean grip force. The contributions of the thumb and ring finger were higher in the pouring task, whereas the contributions of the palm and the index finger were higher in the transport task. Mean force sharing among fingers was 30% for index, 29% for middle, 22% for ring and 19% for little finger. Practitioner Summary: We analysed grip force and force sharing in two manipulation tasks with bottles: transporting and pouring. The objective was to understand the effects of the bottle features, filling level and task on the contribution of different areas of the hand to the grip force. Force sharing was different for each task and the bottles features affected to both grip force and force sharing.

Proximal arm kinematics affect grip force-load force coordination

PubMed Central

Vermillion, Billy C.; Lum, Peter S.

2015-01-01

During object manipulation, grip force is coordinated with load force, which is primarily determined by object kinematics. Proximal arm kinematics may affect grip force control, as proximal segment motion could affect control of distal hand muscles via biomechanical and/or neural pathways. The aim of this study was to investigate the impact of proximal kinematics on grip force modulation during object manipulation. Fifteen subjects performed three vertical lifting tasks that involved distinct proximal kinematics (elbow/shoulder), but resulted in similar end-point (hand) trajectories. While temporal coordination of grip and load forces remained similar across the tasks, proximal kinematics significantly affected the grip force-to-load force ratio (P = 0.042), intrinsic finger muscle activation (P = 0.045), and flexor-extensor ratio (P < 0.001). Biomechanical coupling between extrinsic hand muscles and the elbow joint cannot fully explain the observed changes, as task-related changes in intrinsic hand muscle activation were greater than in extrinsic hand muscles. Rather, between-task variation in grip force (highest during task 3) appears to contrast to that in shoulder joint velocity/acceleration (lowest during task 3). These results suggest that complex neural coupling between the distal and proximal upper extremity musculature may affect grip force control during movements, also indicated by task-related changes in intermuscular coherence of muscle pairs, including intrinsic finger muscles. Furthermore, examination of the fingertip force showed that the human motor system may attempt to reduce variability in task-relevant motor output (grip force-to-load force ratio), while allowing larger fluctuations in output less relevant to task goal (shear force-to-grip force ratio). PMID:26289460

Fitts’ Law in the Control of Isometric Grip Force With Naturalistic Targets

PubMed Central

Thumser, Zachary C.; Slifkin, Andrew B.; Beckler, Dylan T.; Marasco, Paul D.

2018-01-01

Fitts’ law models the relationship between amplitude, precision, and speed of rapid movements. It is widely used to quantify performance in pointing tasks, study human-computer interaction, and generally to understand perceptual-motor information processes, including research to model performance in isometric force production tasks. Applying Fitts’ law to an isometric grip force task would allow for quantifying grasp performance in rehabilitative medicine and may aid research on prosthetic control and design. We examined whether Fitts’ law would hold when participants attempted to accurately produce their intended force output while grasping a manipulandum when presented with images of various everyday objects (we termed this the implicit task). Although our main interest was the implicit task, to benchmark it and establish validity, we examined performance against a more standard visual feedback condition via a digital force-feedback meter on a video monitor (explicit task). Next, we progressed from visual force feedback with force meter targets to the same targets without visual force feedback (operating largely on feedforward control with tactile feedback). This provided an opportunity to see if Fitts’ law would hold without vision, and allowed us to progress toward the more naturalistic implicit task (which does not include visual feedback). Finally, we changed the nature of the targets from requiring explicit force values presented as arrows on a force-feedback meter (explicit targets) to the more naturalistic and intuitive target forces implied by images of objects (implicit targets). With visual force feedback the relation between task difficulty and the time to produce the target grip force was predicted by Fitts’ law (average r2 = 0.82). Without vision, average grip force scaled accurately although force variability was insensitive to the target presented. In contrast, images of everyday objects generated more reliable grip forces without the visualized force meter. In sum, population means were well-described by Fitts’ law for explicit targets with vision (r2 = 0.96) and implicit targets (r2 = 0.89), but not as well-described for explicit targets without vision (r2 = 0.54). Implicit targets should provide a realistic see-object-squeeze-object test using Fitts’ law to quantify the relative speed-accuracy relationship of any given grasper. PMID:29773999

Grip force control in individuals with multiple sclerosis.

PubMed

Iyengar, Veena; Santos, Marcio J; Ko, Michael; Aruin, Alexander S

2009-10-01

Appropriate regulation of grip force is essential in performance of various activities of daily living such as drinking, eating, buttoning a shirt, and so on. The extent to which individuals with multiple sclerosis (MS) are able to regulate grip forces while performing elements of the activities of daily living is largely unknown. . To investigate how individuals with MS control grip force during performance of functional tasks. . This study evaluated the grip force control in selected individuals with MS (n = 9) and healthy control subjects (n = 9) while they performed the task of lifting and placing an instrumented object on a shelf and the task of lifting the object and bringing it close to the mouth to mimic drinking. The grip forces, object acceleration, force ratio, and time lag were recorded and analyzed. . The individuals with MS used significantly larger peak grip force and force ratio than control subjects while performing both tasks and for both hands. In addition, the time lag between the peaks of grip and load forces was significantly longer in individuals with MS. . The application of excessive grip force could predispose individuals with MS to additional fatigue and musculoskeletal overuse trauma. Rehabilitation protocols for the MS population may need to account for increased levels of grip force applied during the performance of functional tasks.

Both vision-for-perception and vision-for-action follow Weber's law at small object sizes, but violate it at larger sizes.

PubMed

Bruno, Nicola; Uccelli, Stefano; Viviani, Eva; de'Sperati, Claudio

2016-10-01

According to a previous report, the visual coding of size does not obey Weber's law when aimed at guiding a grasp (Ganel et al., 2008a). This result has been interpreted as evidence for a fundamental difference between sensory processing in vision-for-perception, which needs to compress a wide range of physical objects to a restricted range of percepts, and vision-for-action when applied to the much narrower range of graspable and reachable objects. We compared finger aperture in a motor task (precision grip) and perceptual task (cross modal matching or "manual estimation" of the object's size). Crucially, we tested the whole range of graspable objects. We report that both grips and estimations clearly violate Weber's law with medium-to-large objects, but are essentially consistent with Weber's law with smaller objects. These results differ from previous characterizations of perception-action dissociations in the precision of representations of object size. Implications for current functional interpretations of the dorsal and ventral processing streams in the human visual system are discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Grip type and task goal modify reach-to-grasp performance in post-stroke hemiparesis.

PubMed

Schaefer, Sydney Y; DeJong, Stacey L; Cherry, Kendra M; Lang, Catherine E

2012-04-01

This study investigated whether grip type and/or task goal influenced reaching and grasping performance in poststroke hemiparesis. Sixteen adults with poststroke hemiparesis and twelve healthy adults reached to and grasped a cylindrical object using one of two grip types (3-finger or palmar) to achieve one of two task goals (hold or lift). Performance of the stroke group was characteristic of hemiparetic limb movement during reach-to-grasp, with more curved handpaths and slower velocities compared with the control group. These effects were present regardless of grip type or task goal. Other measures of reaching (reach time and reach velocity at object contact) and grasping (peak thumb-index finger aperture during the reach and peak grip force during the grasp) were differentially affected by grip type, task goal, or both, despite the presence of hemiparesis, providing new evidence that changes in motor patterns after stroke may occur to compensate for stroke-related motor impairment.

Grip type and task goal modify reach-to-grasp performance in post-stroke hemiparesis

PubMed Central

Schaefer, Sydney Y.; DeJong, Stacey L.; Cherry, Kendra M.; Lang, Catherine E.

2011-01-01

This study investigated whether grip type and/or task goal influenced reaching and grasping performance in post-stroke hemiparesis. Sixteen adults with post-stroke hemiparesis and twelve healthy adults reached to and grasped a cylindrical object using one of two grip types (3-finger or palmar) to achieve one of two task goals (hold or lift). Performance of the stroke group was characteristic of hemiparetic limb movement during reach-to-grasp, with more curved handpaths and slower velocities compared to the control group. These effects were present regardless of grip type or task goal. Other measures of reaching (reach time and reach velocity at object contact) and grasping (peak thumb-index finger aperture during the reach and peak grip force during the grasp) were differentially affected by grip type, task goal, or both, despite the presence of hemiparesis, providing new evidence that changes in motor patterns after stroke may occur to compensate for stroke-related motor impairment. PMID:22357103

Constraints on grip selection in hemiparetic cerebral palsy: effects of lesional side, end-point accuracy, and context.

PubMed

Steenbergen, Bert; Meulenbroek, Ruud G J; Rosenbaum, David A

2004-04-01

This study was concerned with selection criteria used for grip planning in adolescents with left or right hemiparetic cerebral palsy. In the first experiment, we asked participants to pick up a pencil and place the tip in a pre-defined target region. We varied the size of the target to test the hypothesis that increased end-point precision demands would favour the use of a grip that affords end-state comfort. In the second experiment, we studied grip planning in three task contexts that were chosen to let us test the hypothesis that a more functional task context would likewise promote the end-state comfort effect. When movements were performed with the impaired hand, we found that participants with right hemiparesis (i.e., left brain damage) aimed for postural comfort at the start rather than at the end of the object-manipulation phase in both experiments. By contrast, participants with left hemiparesis (i.e., right brain damage) did not favour a particular selection criterion with the impaired hand in the first experiment, but aimed for postural comfort at the start in the second experiment. When movements were performed with the unimpaired hand, grip selection criteria again differed for right and left hemiparetic participants. Participants with right hemiparesis did not favour a particular selection criterion with the unimpaired hand in the first experiment and only showed the end-state comfort effect in the most functional tasks of the second experiment. By contrast, participants with left hemiparesis showed the end-state comfort effect in all conditions of both experiments. These data suggest that the left hemisphere plays a special role in action planning, as has been recognized before, and that one of the deficits accompanying left brain damage is a deficit in forward movement planning, which has not been recognized before. Our findings have both theoretical and clinical implications.

The effect of force feedback delay on stiffness perception and grip force modulation during tool-mediated interaction with elastic force fields

PubMed Central

Karniel, Amir; Nisky, Ilana

2015-01-01

During interaction with objects, we form an internal representation of their mechanical properties. This representation is used for perception and for guiding actions, such as in precision grip, where grip force is modulated with the predicted load forces. In this study, we explored the relationship between grip force adjustment and perception of stiffness during interaction with linear elastic force fields. In a forced-choice paradigm, participants probed pairs of virtual force fields while grasping a force sensor that was attached to a haptic device. For each pair, they were asked which field had higher level of stiffness. In half of the pairs, the force feedback of one of the fields was delayed. Participants underestimated the stiffness of the delayed field relatively to the nondelayed, but their grip force characteristics were similar in both conditions. We analyzed the magnitude of the grip force and the lag between the grip force and the load force in the exploratory probing movements within each trial. Right before answering which force field had higher level of stiffness, both magnitude and lag were similar between delayed and nondelayed force fields. These results suggest that an accurate internal representation of environment stiffness and time delay was used for adjusting the grip force. However, this representation did not help in eliminating the bias in stiffness perception. We argue that during performance of a perceptual task that is based on proprioceptive feedback, separate neural mechanisms are responsible for perception and action-related computations in the brain. PMID:25717155

The effect of force feedback delay on stiffness perception and grip force modulation during tool-mediated interaction with elastic force fields.

PubMed

Leib, Raz; Karniel, Amir; Nisky, Ilana

2015-05-01

During interaction with objects, we form an internal representation of their mechanical properties. This representation is used for perception and for guiding actions, such as in precision grip, where grip force is modulated with the predicted load forces. In this study, we explored the relationship between grip force adjustment and perception of stiffness during interaction with linear elastic force fields. In a forced-choice paradigm, participants probed pairs of virtual force fields while grasping a force sensor that was attached to a haptic device. For each pair, they were asked which field had higher level of stiffness. In half of the pairs, the force feedback of one of the fields was delayed. Participants underestimated the stiffness of the delayed field relatively to the nondelayed, but their grip force characteristics were similar in both conditions. We analyzed the magnitude of the grip force and the lag between the grip force and the load force in the exploratory probing movements within each trial. Right before answering which force field had higher level of stiffness, both magnitude and lag were similar between delayed and nondelayed force fields. These results suggest that an accurate internal representation of environment stiffness and time delay was used for adjusting the grip force. However, this representation did not help in eliminating the bias in stiffness perception. We argue that during performance of a perceptual task that is based on proprioceptive feedback, separate neural mechanisms are responsible for perception and action-related computations in the brain. Copyright © 2015 the American Physiological Society.

Selective deficits of grip force control during object manipulation in patients with reduced sensibility of the grasping digits.

PubMed

Nowak, Dennis A; Hermsdörfer, Joachim

2003-09-01

Persons with impaired manual sensibility frequently report problems to use the hand in manipulative tasks, such as using tools or buttoning a shirt. At least two control processes determine grip forces during voluntary object manipulation. Anticipatory force control specifies the motor commands on the basis of predictions about physical object properties and the consequences of our own actions. Feedback sensory information from the grasping digits, representing mechanical events at the skin-object interface, automatically modifies grip force according to the actual loading requirements and updates sensorimotor memories to support anticipatory grip force control. We investigated grip force control in nine patients with moderately impaired tactile sensibility of the grasping digits and in nine sex- and age-matched healthy controls lifting and holding an instrumented object. In healthy controls grip force was adequately scaled to the weight of the object to be lifted. The grip force was programmed to smoothly change in parallel with load force over the entire lifting movement. In particular, the grip force level was regulated in an economical way to be always slightly higher than the minimum required to prevent the object slipping. The temporal coupling between the grip and load force profiles achieved a high precision with the maximum grip and load forces coinciding closely in time. For the temporal regulation of the grip force profile patients with impaired tactile sensibility maintained the close co-ordination between proximal arm muscles, responsible for the lifting movement and the fingers stabilising the grasp. Maximum grip force coincided with maximum acceleration of the lifting movement. However, patients employed greater maximum grip forces and greater grip forces to hold the object unsupported when compared with controls. Our results give further evidence to the suggestion that during manipulation of objects with known physical properties the anticipatory temporal regulation of the grip force profile is centrally processed and less under sensory feedback control. In contrast, sensory afferent information from the grasping fingers plays a dominant role for the efficient scaling of the grip force level according to actual loading requirements.

Estimating thumb–index finger precision grip and manipulation potential in extant and fossil primates

PubMed Central

Feix, Thomas; Kivell, Tracy L.; Pouydebat, Emmanuelle; Dollar, Aaron M.

2015-01-01

Primates, and particularly humans, are characterized by superior manual dexterity compared with other mammals. However, drawing the biomechanical link between hand morphology/behaviour and functional capabilities in non-human primates and fossil taxa has been challenging. We present a kinematic model of thumb–index precision grip and manipulative movement based on bony hand morphology in a broad sample of extant primates and fossil hominins. The model reveals that both joint mobility and digit proportions (scaled to hand size) are critical for determining precision grip and manipulation potential, but that having either a long thumb or great joint mobility alone does not necessarily yield high precision manipulation. The results suggest even the oldest available fossil hominins may have shared comparable precision grip manipulation with modern humans. In particular, the predicted human-like precision manipulation of Australopithecus afarensis, approximately one million years before the first stone tools, supports controversial archaeological evidence of tool-use in this taxon. PMID:25878134

Estimating thumb-index finger precision grip and manipulation potential in extant and fossil primates.

PubMed

Feix, Thomas; Kivell, Tracy L; Pouydebat, Emmanuelle; Dollar, Aaron M

2015-05-06

Primates, and particularly humans, are characterized by superior manual dexterity compared with other mammals. However, drawing the biomechanical link between hand morphology/behaviour and functional capabilities in non-human primates and fossil taxa has been challenging. We present a kinematic model of thumb-index precision grip and manipulative movement based on bony hand morphology in a broad sample of extant primates and fossil hominins. The model reveals that both joint mobility and digit proportions (scaled to hand size) are critical for determining precision grip and manipulation potential, but that having either a long thumb or great joint mobility alone does not necessarily yield high precision manipulation. The results suggest even the oldest available fossil hominins may have shared comparable precision grip manipulation with modern humans. In particular, the predicted human-like precision manipulation of Australopithecus afarensis, approximately one million years before the first stone tools, supports controversial archaeological evidence of tool-use in this taxon. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Coordination of precision grip in 2–6 years-old children with autism spectrum disorders compared to children developing typically and children with developmental disabilities

PubMed Central

David, Fabian J.; Baranek, Grace T.; Wiesen, Chris; Miao, Adrienne F.; Thorpe, Deborah E.

2012-01-01

Impaired motor coordination is prevalent in children with Autism Spectrum Disorders (ASD) and affects adaptive skills. Little is known about the development of motor patterns in young children with ASD between 2 and 6 years of age. The purpose of the current study was threefold: (1) to describe developmental correlates of motor coordination in children with ASD, (2) to identify the extent to which motor coordination deficits are unique to ASD by using a control group of children with other developmental disabilities (DD), and (3) to determine the association between motor coordination variables and functional fine motor skills. Twenty-four children with ASD were compared to 30 children with typical development (TD) and 11 children with DD. A precision grip task was used to quantify and analyze motor coordination. The motor coordination variables were two temporal variables (grip to load force onset latency and time to peak grip force) and two force variables (grip force at onset of load force and peak grip force). Functional motor skills were assessed using the Fine Motor Age Equivalents of the Vineland Adaptive Behavior Scale and the Mullen Scales of Early Learning. Mixed regression models were used for all analyses. Children with ASD presented with significant motor coordination deficits only on the two temporal variables, and these variables differentiated children with ASD from the children with TD, but not from children with DD. Fine motor functional skills had no statistically significant associations with any of the motor coordination variables. These findings suggest that subtle problems in the timing of motor actions, possibly related to maturational delays in anticipatory feed-forward mechanisms, may underlie some motor deficits reported in children with ASD, but that these issues are not unique to this population. Further research is needed to investigate how children with ASD or DD compensate for motor control deficits to establish functional skills. PMID:23293589

Dynamical Coordination of Hand Intrinsic Muscles for Precision Grip in Diabetes Mellitus.

PubMed

Li, Ke; Wei, Na; Cheng, Mei; Hou, Xingguo; Song, Jun

2018-03-12

This study investigated the effects of diabetes mellitus (DM) on dynamical coordination of hand intrinsic muscles during precision grip. Precision grip was tested using a custom designed apparatus with stable and unstable loads, during which the surface electromyographic (sEMG) signals of the abductor pollicis brevis (APB) and first dorsal interosseous (FDI) were recorded simultaneously. Recurrence quantification analysis (RQA) was applied to quantify the dynamical structure of sEMG signals of the APB and FDI; and cross recurrence quantification analysis (CRQA) was used to assess the intermuscular coupling between the two intrinsic muscles. This study revealed that the DM altered the dynamical structure of muscle activation for the FDI and the dynamical intermuscular coordination between the APB and FDI during precision grip. A reinforced feedforward mechanism that compensates the loss of sensory feedbacks in DM may be responsible for the stronger intermuscular coupling between the APB and FDI muscles. Sensory deficits in DM remarkably decreased the capacity of online motor adjustment based on sensory feedback, rendering a lower adaptability to the uncertainty of environment. This study shed light on inherent dynamical properties underlying the intrinsic muscle activation and intermuscular coordination for precision grip and the effects of DM on hand sensorimotor function.

The interdigital brace and other grips for termite nest perforation by chimpanzees of the Goualougo Triangle, Republic of Congo.

PubMed

Lesnik, Julie J; Sanz, Crickette M; Morgan, David B

2015-06-01

Studies of chimpanzee termite foraging enlighten our understanding of early hominin tool use not only by modeling the cognitive ability of our ancestors but also by emphasizing the possible role of social insects in the hominin diet. The chimpanzees of the Goualougo Triangle are known to have one of the largest and most complex tool repertoires reported for wild chimpanzees. One tool set habitually used by this population includes a perforating tool to penetrate the hard outer crust of elevated termite nests before fishing for termite prey with an herbaceous stem. Here, we report the variation present in the grips used on the perforating tool. Our analysis of video recordings of chimpanzee visitation to termite nests over a 3-year period shows that these chimpanzees use a variety of grips to navigate the challenges encountered in opening a termite nest. For situations in which the soil is most hardened, perforating requires force and a power grip is often used. When the soil in the passageway is loose, precision grips are suitable for the task. One of the preferred grips reported here is an interdigital brace, which has previously been described in studies of how some people hold a pencil. In this study, for the first time, the interdigital brace has been thoroughly described for chimpanzees. The various strategies and grips used during perforation emphasize the importance of termites as a nutritional resource that should be considered more strongly as a food used by early hominins. © 2015 Wiley Periodicals, Inc.

Constrained handgrip force decreases upper extremity muscle activation and arm strength.

PubMed

Smets, Martin P H; Potvin, James R; Keir, Peter J

2009-09-01

Many industrial tasks require repetitive shoulder exertions to be performed with concurrent physical and mental demands. The highly mobile nature of the shoulder predisposes it to injury. The purpose of this study was to determine the effects of simultaneous gripping, at a specified magnitude, on muscle activity and maximal arm force in various directions. Ten female subjects performed maximal arm exertions at two different heights and five directions using both specified (30% maximum voluntary grip) and preferred (self-selected) grip forces. Electromyography was recorded from eight muscles of the right upper extremity. The preferred grip condition produced grip forces that were dependent on the combination of arm height and force direction and were significantly greater (arm force down), lower (to left, up and push forward), or similar to the specified grip condition. Regardless of the magnitude of the preferred grip force, specifying the grip resulted in decreased maximal arm strength (by 18-25%) and muscle activity (by 15-30%) in all conditions, indicating an interfering effect when the grip force was specified by visual target force-matching. Task constraints, such as specific gripping demands, may decrease peak force levels attainable and alter muscle activity. Depending on the nature of task, the amount of relative demand may differ, which should be considered when determining safety thresholds.

The handyman's brain: a neuroimaging meta-analysis describing the similarities and differences between grip type and pattern in humans.

PubMed

King, M; Rauch, H G; Stein, D J; Brooks, S J

2014-11-15

Handgrip is a ubiquitous human movement that was critical in our evolution. However, the differences in brain activity between grip type (i.e. power or precision) and pattern (i.e. dynamic or static) are not fully understood. In order to address this, we performed Activation Likelihood Estimation (ALE) analysis between grip type and grip pattern using functional magnetic resonance imaging (fMRI) data. ALE provides a probabilistic summary of the BOLD response in hundreds of subjects, which is often beyond the scope of a single fMRI experiment. We collected data from 28 functional magnetic resonance data sets, which included a total of 398 male and female subjects. Using ALE, we analyzed the BOLD response during power, precision, static and dynamic grip in a range of forces and age in right handed healthy individuals without physical impairment, cardiovascular or neurological dysfunction using a variety of grip tools, feedback and experimental training. Power grip generates unique activation in the postcentral gyrus (areas 1 and 3b) and precision grip generates unique activation in the supplementary motor area (SMA, area 6) and precentral gyrus (area 4a). Dynamic handgrip generates unique activation in the precentral gyrus (area 4p) and SMA (area 6) and of particular interest, both dynamic and static grip share activation in the area 2 of the postcentral gyrus, an area implicated in the evolution of handgrip. According to effect size analysis, precision and dynamic grip generates stronger activity than power and static, respectively. Our study demonstrates specific differences between grip type and pattern. However, there was a large degree of overlap in the pre and postcentral gyrus, SMA and areas of the frontal-parietal-cerebellar network, which indicates that other mechanisms are potentially involved in regulating handgrip. Further, our study provides empirically based regions of interest, which can be downloaded here within, that can be used to more effectively study power grip in a range of populations and conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

The effect of grip force, stroke rotation and frequency on discomfort for a torqueing tasks.

PubMed

Bano, Farheen; Mallick, Zulqernian; Khan, Abid Ali

2015-08-08

Occupational tasks involve awkward upper limb postures, especially movement of forearm with repetitive combined gripping and torqueing exertions, which may lead to development of WMSDs. From the literature survey it was observed that there was a lack of studies focussed on the combined effect of torque and grip exertions on forearm discomfort. The present study was to investigate the effects of grip force, stroke rotation and frequency of exertions on discomfort and Electromyography (EMG) activities of the forearm muscles in a repetitive torqueing task. Twenty-seven male participants volunteered in this study. The participants performed repetitive exertions for a 5 minutes duration for each combination of the different levels of stroke rotation, grip force and frequency of exertions. Three levels of stroke rotation, three levels of grip force and three levels of frequency of exertion were chosen as independent variables. Therefore a 3 × 3 customized factorial design was used for the experiment for each level of grip force. Hence, the study was divided into three groups on the basis of grip force (50N, 70N and 90N). The ANOVA showed that stroke rotation and frequency of exertion were significant on discomfort. Further Students Newmann test (SNK) revealed that discomfort was increased with increasing stroke rotation and frequency of exertion. The multivariate analysis of variances (MANOVA) performed on EMG data instead of ANOVA because EMG activities of five muscles simultaneously were recorded. The Results found that extensor muscles were more fatigued in torqueing with gripping task. It was found that stroke rotation for the torqueing tasks must be kept below 45°. It was concluded that it is important to control stroke rotation to improve performance of repetitive torqueing activity.

Effect of blocking tactile information from the fingertips on adaptation and execution of grip forces to friction at the grasping surface.

PubMed

Bilaloglu, Seda; Lu, Ying; Geller, Daniel; Rizzo, John Ross; Aluru, Viswanath; Gardner, Esther P; Raghavan, Preeti

2016-03-01

Adaptation of fingertip forces to friction at the grasping surface is necessary to prevent use of inadequate or excessive grip forces. In the current study we investigated the effect of blocking tactile information from the fingertips noninvasively on the adaptation and efficiency of grip forces to surface friction during precision grasp. Ten neurologically intact subjects grasped and lifted an instrumented grip device with 18 different frictional surfaces under three conditions: with bare hands or with a thin layer of plastic (Tegaderm) or an additional layer of foam affixed to the fingertips. The coefficient of friction at the finger-object interface of each surface was obtained for each subject with bare hands and Tegaderm by measuring the slip ratio (grip force/load force) at the moment of slip. We found that the foam layer reduced sensibility for two-point discrimination and pressure sensitivity at the fingertips, but Tegaderm did not. However, Tegaderm reduced static, but not dynamic, tactile discrimination. Adaptation of fingertip grip forces to surface friction measured by the rate of change of peak grip force, and grip force efficiency measured by the grip-load force ratio at lift, showed a proportional relationship with bare hands but were impaired with Tegaderm and foam. Activation of muscles engaged in precision grip also varied with the frictional surface with bare hands but not with Tegaderm and foam. The results suggest that sensitivity for static tactile discrimination is necessary for feedforward and feedback control of grip forces and for adaptive modulation of muscle activity during precision grasp. Copyright © 2016 the American Physiological Society.

Variation in work tasks in relation to pinch grip strength among middle-aged female dentists.

PubMed

Ding, Hebo; Leino-Arjas, Päivi; Murtomaa, Heikki; Takala, Esa-Pekka; Solovieva, Svetlana

2013-11-01

We aimed to investigate the relationship of task variation during dental work history with pinch grip strength among dentists. We measured pinch grip strength among 295 female Finnish dentists aged 45-63 years. Variation in dental work tasks during work history was empirically defined by cluster analysis. Three clusters of task variation emerged: low (most work time in restoration treatment/endodontics), moderate (about 50% in the former and 50% in prosthodontics/periodontics/surgery), and high (variable tasks including administrative duties). Hand radiographs were examined for the presence of OA in the wrist and each joint of the 1-3rd fingers. Information on hand-loading leisure-time activities, and joint pain was obtained by questionnaire. Glove size was used as a proxy for hand size. BMI (kg/m2) was based on measured weight and self-reported height. Dentists with low variation of work task history had an increased risk of low pinch grip strength in the right hand (OR 2.3, 95% CI 1.2-4.3), but not in the left (1.13, 0.62-2.08), compared to dentists with high task variation, independent of age, hand size, hand-loading leisure-time activities, BMI and symptomatic hand OA. The dentists with the most hand-loading tasks were at an increased risk of low pinch grip strength, independent of e.g. symptomatic hand OA. It is advisable among dentists to perform as diverse work tasks as possible to reduce the risk of decreased pinch grip strength. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

A Hexapod Robot to Demonstrate Mesh Walking in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Foor, David C.

2005-01-01

The JPL Micro-Robot Explorer (MRE) Spiderbot is a robot that takes advantage of its small size to perform precision tasks suitable for space applications. The Spiderbot is a legged robot that can traverse harsh terrain otherwise inaccessible to wheeled robots. A team of Spiderbots can network and can exhibit collaborative efforts to SUCCeSSfUlly complete a set of tasks. The Spiderbot is designed and developed to demonstrate hexapods that can walk on flat surfaces, crawl on meshes, and assemble simple structures. The robot has six legs consisting of two spring-compliant joints and a gripping actuator. A hard-coded set of gaits allows the robot to move smoothly in a zero-gravity environment along the mesh. The primary objective of this project is to create a Spiderbot that traverses a flexible, deployable mesh, for use in space repair. Verification of this task will take place aboard a zero-gravity test flight. The secondary objective of this project is to adapt feedback from the joints to allow the robot to test each arm for a successful grip of the mesh. The end result of this research lends itself to a fault-tolerant robot suitable for a wide variety of space applications.

The effect of ergonomic laparoscopic tool handle design on performance and efficiency.

PubMed

Tung, Kryztopher D; Shorti, Rami M; Downey, Earl C; Bloswick, Donald S; Merryweather, Andrew S

2015-09-01

Many factors can affect a surgeon's performance in the operating room; these may include surgeon comfort, ergonomics of tool handle design, and fatigue. A laparoscopic tool handle designed with ergonomic considerations (pistol grip) was tested against a current market tool with a traditional pinch grip handle. The goal of this study is to quantify the impact ergonomic design considerations which have on surgeon performance. We hypothesized that there will be measurable differences between the efficiency while performing FLS surgical trainer tasks when using both tool handle designs in three categories: time to completion, technical skill, and subjective user ratings. The pistol grip incorporates an ergonomic interface intended to reduce contact stress points on the hand and fingers, promote a more neutral operating wrist posture, and reduce hand tremor and fatigue. The traditional pinch grip is a laparoscopic tool developed by Stryker Inc. widely used during minimal invasive surgery. Twenty-three (13 M, 10 F) participants with no existing upper extremity musculoskeletal disorders or experience performing laparoscopic procedures were selected to perform in this study. During a training session prior to testing, participants performed practice trials in a SAGES FLS trainer with both tools. During data collection, participants performed three evaluation tasks using both handle designs (order was randomized, and each trial completed three times). The tasks consisted of FLS peg transfer, cutting, and suturing tasks. Feedback from test participants indicated that they significantly preferred the ergonomic pistol grip in every category (p < 0.05); most notably, participants experienced greater degrees of discomfort in their hands after using the pinch grip tool. Furthermore, participants completed cutting and peg transfer tasks in a shorter time duration (p < 0.05) with the pistol grip than with the pinch grip design; there was no significant difference between completion times for the suturing task. Finally, there was no significant interaction between tool type and errors made during trials. There was a significant preference for as well as lower pain experienced during use of the pistol grip tool as seen from the survey feedback. Both evaluation tasks (cutting and peg transfer) were also completed significantly faster with the pistol grip tool. Finally, due to the high degree of variability in the error data, it was not possible to draw any meaningful conclusions about the effect of tool design on the number or degree of errors made.

Enslaving in a serial chain: interactions between grip force and hand force in isometric tasks.

PubMed

Paclet, Florent; Ambike, Satyajit; Zatsiorsky, Vladimir M; Latash, Mark L

2014-03-01

This study was motivated by the double action of extrinsic hand muscles that produce grip force and also contribute to wrist torque. We explored interactions between grip force and wrist torque in isometric force production tasks. In particular, we tested a hypothesis that an intentional change in one of the two kinetic variables would produce an unintentional change in the other (enslaving). When young healthy subjects produced accurate changes in the grip force, only minor effects on the force produced by the hand (by wrist flexion/extension action) were observed. In contrast, a change in the hand force produced consistent changes in grip force in the same direction. The magnitude of such unintentional grip force change was stronger for intentional hand force decrease as compared to hand force increase. These effects increased with the magnitude of the initial grip force. When the subjects were asked to produce accurate total force computed as the sum of the hand and grip forces, strong negative covariation between the two forces was seen across trials interpreted as a synergy stabilizing the total force. An index of this synergy was higher in the space of "modes," hypothetical signals to the two effectors that could be changed by the controller one at a time. We interpret the complex enslaving effects (positive force covariation) as conditioned by typical everyday tasks. The presence of synergic effects (negative, task-specific force covariation) can be naturally interpreted within the referent configuration hypothesis.

Enslaving in a serial chain: Interactions between grip force and hand force in isometric tasks

PubMed Central

Paclet, Florent; Ambike, Satyajit; Zatsiorsky, Vladimir M.; Latash, Mark L.

2014-01-01

This study was motivated by the double action of extrinsic hand muscles that produce grip force and also contribute to wrist torque. We explored interactions between grip force and wrist torque in isometric force production tasks. In particular, we tested a hypothesis that an intentional change in one of the two kinetic variables would produce an unintentional change in the other (enslaving). When young healthy subjects produced accurate changes in the grip force, only minor effects on the force produced by the hand (by wrist flexion/extension action) were observed. In contrast, a change in the hand force produced consistent changes in grip force in the same direction. The magnitude of such unintentional grip force change was stronger for intentional hand force decrease as compared to hand force increase. These effects increased with the magnitude of the initial grip force. When the subjects were asked to produce accurate total force computed as the sum of the hand and grip forces, strong negative co-variation between the two forces was seen across trials interpreted as a synergy stabilizing the total force. An index of this synergy was higher in the space of “modes”, hypothetical signals to the two effectors that could be changed by the controller one at a time. We interpret the complex enslaving effects (positive force co-variation) as conditioned by typical everyday tasks. The presence of synergic effects (negative, task-specific force co-variation) can be naturally interpreted within the referent configuration hypothesis. PMID:24309747

Effects of High-Frequency Repetitive Transcranial Magnetic Stimulation Combined with Task-Oriented Mirror Therapy Training on Hand Rehabilitation of Acute Stroke Patients.

PubMed

Kim, Jinhong; Yim, Jongeun

2018-02-06

BACKGROUND Impairments of hand function make it difficult to perform daily life activities and to return to work. The aim of this study was to investigate the effect of high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) combined with task-oriented mirror therapy (TOMT) on hand rehabilitation in acute stroke patients. MATERIAL AND METHODS Twenty subacute stroke patients in the initial stages (<3 months) participated in the study. Subjects were allocated to 2 groups: the experimental group received HF-rTMS + TOMT and the control group received HF-rTMS. TOMT training was conducted in 10 sessions over 2 weeks for 30 min. rTMS was applied at a 20 Hz frequency over the hand motor area in the cortex of the affected hemisphere for 15 min. Outcomes, including motor-evoked potential (MEP), pinch grip, hand grip, and box and block test, were measured before and after training. RESULTS Significant improvements in the MEP and hand function variables were observed in both groups (p<0.05). In particular, hand functions (pinch grip and box and block test) were significantly different between the 2 groups (p<0.05). CONCLUSIONS HF-rTMS combined with TOMT had a positive effect on hand function and can be used for the rehabilitation of precise hand movements in acute stroke patients.

Predictive and Reactive Grip Force Responses to Rapid Load Increases in People With Multiple Sclerosis.

PubMed

Allgöwer, Kathrin; Kern, Claudia; Hermsdörfer, Joachim

2017-03-01

To determine the effects of multiple sclerosis (MS) on predictive and reactive grip force control in a catching task and on clinical tests of hand function. Case-control study with matched-pairs control group. University prevention and rehabilitation center. Participants (N=30) consisted of people with multiple sclerosis (PwMS) (n=15) and healthy controls (n=15), matched for sex, age, and hand dominance. Not applicable. Performance on the Expanded Disability Status Scale (EDSS), Nine-Hole Peg Test (9-HPT), Jebsen-Taylor Hand Function Test (JTHFT), and 2-point discrimination (2PD) was evaluated. To analyze grip force control, blindfolded subjects held a receptacle equipped with grip force and acceleration sensors in their hand. In a catching task, a weight was dropped from (1) the experimenter's hand unexpectedly into the receptacle (reactive force control); and (2) from the subject's opposite hand (predictive force control). Grip forces and time lags were analyzed. PwMS (mean EDSS ± SD, 4.2±1.86) had impairments in the 9-HPT and JTHFT (P<.001). The 2PD did not differ significantly between PwMS and controls. During reactive force control (catching task 1), PwMS showed significantly higher grip forces immediately after impact (P<.05), and a significant prolongation of the time from grip force increase until reaching the peak of grip force (P<.001). PwMS and controls did not differ during predictive force control (catching task 2; P>.1). Exaggerated grip force responses and alterations of timing after an unpredictable perturbation, combined with preserved grip force control during predictable conditions, is a characteristic pattern of fine motor control deficits in MS. Measures of reactive grip force responses may be used to complement neurologic assessments. Further studies exploring the usefulness of these measures should be performed in a broader community of PwMS. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Using grasping tasks to evaluate hand force coordination in children with hemiplegic cerebral palsy.

PubMed

Mackenzie, Samuel J; Getchell, Nancy; Modlesky, Christopher M; Miller, Freeman; Jaric, Slobodan

2009-08-01

Mackenzie SJ, Getchell N, Modlesky CM, Miller F, Jaric S. Using grasping tasks to evaluate hand force coordination in children with hemiplegic cerebral palsy. To assess force coordination in children with hemiplegic cerebral palsy (CP) using a device that allows for testing both unimanual and bimanual manipulation tasks performed under static and dynamic conditions. Nonequivalent groups design. University research laboratory for motor control. Six children with hemiplegic CP (age, mean +/- SD, 11.6+/-1.8 y) and 6 typically developing controls (11.6+/-1.6 y). Not applicable. Children performed simple lifting and force-matching static ramp tasks by way of both unimanual and bimanual pulling using a device that measures grip force (force acting perpendicularly at the digits-device contact area) and load force (tangential force). Main outcome measures were grip/load force ratios (grip force scaling) and correlation coefficients (force coupling). CP subjects showed significantly higher grip/load force ratios (P<.05) and slightly lower correlation coefficients than the control group, with more pronounced differences for most tasks when using their involved hand. For subjects with CP, switching from unimanual to bimanual conditions did not bring changes in scaling or coupling for the involved hand (P>.05). Compared with healthy children, the impaired hand function in the hemiplegic CP pediatric population could be reflected in excessive grip force that is also decoupled from ongoing changes in load force. Therefore, the bimanual grip load device used in this study could provide a sensitive measure of grip force coordination in CP, although nonmotor deficits should be taken into account when asking children to perform more complex tasks.

Task specific grip force control in writer's cramp.

PubMed

Schneider, A S; Fürholzer, W; Marquardt, C; Hermsdörfer, J

2014-04-01

Writer's cramp is defined as a task specific focal dystonia generating hypertonic muscle co-contractions during handwriting resulting in impaired writing performance and exaggerated finger force. However, little is known about the generalisation of grip force across tasks others than writing. The aim of the study was to directly compare regulation of grip forces during handwriting with force regulation in other fine-motor tasks in patients and control subjects. Handwriting, lifting and cyclic movements of a grasped object were investigated in 21 patients and 14 controls. The applied forces were registered in all three tasks and compared between groups and tasks. In addition, task-specific measures of fine-motor skill were assessed. As expected, patients generated exaggerated forces during handwriting compared to control subjects. However there were no statistically significant group differences during lifting and cyclic movements. The control group revealed a generalisation of grip forces across manual tasks whereas in patients there was no such correlation. We conclude that increased finger forces during handwriting are a task-specific phenomenon that does not necessarily generalise to other fine-motor tasks. Force control of patients with writer's cramp in handwriting and other fine-motor tasks is characterised by individualised control strategies. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Hand grips strength effect on motor function in human brain using fMRI: a pilot study

NASA Astrophysics Data System (ADS)

Ismail, S. S.; Mohamad, M.; Syazarina, S. O.; Nafisah, W. Y.

2014-11-01

Several methods of motor tasks for fMRI scanning have been evolving from simple to more complex tasks. Motor tasks on upper extremity were applied in order to excite the increscent of motor activation on contralesional and ipsilateral hemispheres in brain. The main objective of this study is to study the different conditions for motor tasks on upper extremity that affected the brain activation. Ten healthy right handed with normal vision (3 male and 7 female, age range=20-30 years, mean=24.6 years, SD=2.21) participated in this study. Prior to the scanning, participants were trained on hand grip tasks using rubber ball and pressure gauge tool outside the scanner. During fMRI session, a block design with 30-s task blocks and alternating 30-s rest periods was employed while participants viewed a computer screen via a back projection-mirror system and instructed to follow the instruction by gripping their hand with normal and strong grips using a rubber ball. Statistical Parametric mapping (SPM8) software was used to determine the brain activation. Both tasks activated the primary motor (M1), supplementary motor area (SMA), dorsal and ventral of premotor cortex area (PMA) in left hemisphere while in right hemisphere the area of primary motor (M1) somatosensory was activated. However, the comparison between both tasks revealed that the strong hand grip showed the higher activation at M1, PMA and SMA on left hemisphere and also the area of SMA on right hemisphere. Both conditions of motor tasks could provide insights the functional organization on human brain.

Shared processing of planning articulatory gestures and grasping.

PubMed

Vainio, L; Tiainen, M; Tiippana, K; Vainio, M

2014-07-01

It has been proposed that articulatory gestures are shaped by tight integration in planning mouth and hand acts. This hypothesis is supported by recent behavioral evidence showing that response selection between the precision and power grip is systematically influenced by simultaneous articulation of a syllable. For example, precision grip responses are performed relatively fast when the syllable articulation employs the tongue tip (e.g., [te]), whereas power grip responses are performed relatively fast when the syllable articulation employs the tongue body (e.g., [ke]). However, this correspondence effect, and other similar effects that demonstrate the interplay between grasping and articulatory gestures, has been found when the grasping is performed during overt articulation. The present study demonstrates that merely reading the syllables silently (Experiment 1) or hearing them (Experiment 2) results in a similar correspondence effect. The results suggest that the correspondence effect is based on integration in planning articulatory gestures and grasping rather than requiring an overt articulation of the syllables. We propose that this effect reflects partially overlapped planning of goal shapes of the two distal effectors: a vocal tract shape for articulation and a hand shape for grasping. In addition, the paper shows a pitch-grip correspondence effect in which the precision grip is associated with a high-pitched vocalization of the auditory stimuli and the power grip is associated with a low-pitched vocalization. The underlying mechanisms of this phenomenon are discussed in relation to the articulation-grip correspondence.

Short-Term Effects of Whole-Body Vibration Combined with Task-Related Training on Upper Extremity Function, Spasticity, and Grip Strength in Subjects with Poststroke Hemiplegia: A Pilot Randomized Controlled Trial.

PubMed

Lee, Jung-Sun; Kim, Chang-Yong; Kim, Hyeong-Dong

2016-08-01

The aim of this study was to determine the effect of whole-body vibration training combined with task-related training on arm function, spasticity, and grip strength in subjects with poststroke hemiplegia. Forty-five subjects with poststroke were randomly allocated to 3 groups, each with 15 subjects as follows: control group, whole-body vibration group, and whole-body vibration plus task-related training group. Outcome was evaluated by clinical evaluation and measurements of the grip strength before and 4 weeks after intervention. Our results show that there was a significantly greater increase in the Fugl-Meyer scale, maximal grip strength of the affected hand, and grip strength normalized to the less affected hand in subjects undergoing the whole-body vibration training compared with the control group after the test. Furthermore, there was a significantly greater increase in the Wolf motor function test and a decrease in the modified Ashworth spasticity total scores in subjects who underwent whole-body vibration plus task-related training compared with those in the other 2 groups after the test. The findings indicate that the use of whole-body vibration training combined with task-related training has more benefits on the improvement of arm function, spasticity, and maximal grip strength than conventional upper limb training alone or with whole-body vibration in people with poststroke hemiplegia.

Grip force control during virtual object interaction: effect of force feedback,accuracy demands, and training.

PubMed

Gibo, Tricia L; Bastian, Amy J; Okamura, Allison M

2014-03-01

When grasping and manipulating objects, people are able to efficiently modulate their grip force according to the experienced load force. Effective grip force control involves providing enough grip force to prevent the object from slipping, while avoiding excessive force to avoid damage and fatigue. During indirect object manipulation via teleoperation systems or in virtual environments, users often receive limited somatosensory feedback about objects with which they interact. This study examines the effects of force feedback, accuracy demands, and training on grip force control during object interaction in a virtual environment. The task required subjects to grasp and move a virtual object while tracking a target. When force feedback was not provided, subjects failed to couple grip and load force, a capability fundamental to direct object interaction. Subjects also exerted larger grip force without force feedback and when accuracy demands of the tracking task were high. In addition, the presence or absence of force feedback during training affected subsequent performance, even when the feedback condition was switched. Subjects' grip force control remained reminiscent of their employed grip during the initial training. These results motivate the use of force feedback during telemanipulation and highlight the effect of force feedback during training.

Moving objects with clumsy fingers: how predictive is grip force control in patients with impaired manual sensibility?

PubMed

Nowak, Dennis A; Hermsdörfer, Joachim; Marquardt, Christian; Topka, Helge

2003-03-01

Anticipatory grip force adjustments to movement-induced load fluctuations of a hand-held object suggest that motion planning is based on an internal forward model of both the external object properties and the dynamics of the own motor apparatus. However, the central nervous system also refers to real time sensory feedback from the grasping digits in order to achieve a highly economical coupling between grip force and the actual loading requirements. We analyzed grip force control during vertical point-to-point arm movements with a hand-held instrumented object in 9 patients with moderately impaired tactile sensibility of the grasping digits due to chronic median nerve compression (n = 3), axonal (n = 3) and demyelinating sensory polyneuropathy (n = 3) in comparison to 9 healthy age- and sex-matched control subjects. Point-to-point arm movements started and ended with the object being held stationary at rest. Load force changes arose from inertial loads related to the movement. A maximum of load force occurred early in upward and near the end of downward movements. Compared to healthy controls, patients with impaired manual sensibility generated similar static grip forces during stationary holding of the object and similar force ratios between maximum grip and load force. These findings reflect effective grip force scaling in relation to the movement-induced loads despite reduced afferent feedback from the grasping digits. For both groups the maxima of grip and load force coincided very closely in time, indicating that the temporal regulation of the grip force profile with the load profile was processed with a similar high precision. In addition, linear regression analyses between grip and load forces during movement-related load increase and load decrease phases revealed a similar precise temporo-spatial coupling between grip and load forces for patients and controls. Our results suggest that the precise and anticipatory adjustment of the grip force profile to the load force profile arising from voluntary arm movements with a hand-held object is centrally mediated and less under sensory feedback control. As suggested by previous investigations, the efficient scaling of the grip force magnitude in relation to the movement-induced loads may be intact when deficits of tactile sensibility from the grasping fingers are moderate.

Grip Force Control Is Dependent on Task Constraints in Children with and without Developmental Coordination Disorder

ERIC Educational Resources Information Center

Law, Sui-Heung; Lo, Sing Kai; Chow, Susanna; Cheing, Gladys L.Y.

2011-01-01

Excessive grip force (GF) is often found in children with developmental coordination disorder (DCD). However, their GF control may vary when task constraints are imposed upon their motor performance. This study aimed to investigate how their GF control changes in response to task demands, and to examine their tactile sensitivity. Twenty-one…

Intelligent, self-contained robotic hand

DOEpatents

Krutik, Vitaliy; Doo, Burt; Townsend, William T.; Hauptman, Traveler; Crowell, Adam; Zenowich, Brian; Lawson, John

2007-01-30

A robotic device has a base and at least one finger having at least two links that are connected in series on rotary joints with at least two degrees of freedom. A brushless motor and an associated controller are located at each joint to produce a rotational movement of a link. Wires for electrical power and communication serially connect the controllers in a distributed control network. A network operating controller coordinates the operation of the network, including power distribution. At least one, but more typically two to five, wires interconnect all the controllers through one or more joints. Motor sensors and external world sensors monitor operating parameters of the robotic hand. The electrical signal output of the sensors can be input anywhere on the distributed control network. V-grooves on the robotic hand locate objects precisely and assist in gripping. The hand is sealed, immersible and has electrical connections through the rotary joints for anodizing in a single dunk without masking. In various forms, this intelligent, self-contained, dexterous hand, or combinations of such hands, can perform a wide variety of object gripping and manipulating tasks, as well as locomotion and combinations of locomotion and gripping.

Process for anodizing a robotic device

DOEpatents

Townsend, William T [Weston, MA

2011-11-08

A robotic device has a base and at least one finger having at least two links that are connected in series on rotary joints with at least two degrees of freedom. A brushless motor and an associated controller are located at each joint to produce a rotational movement of a link. Wires for electrical power and communication serially connect the controllers in a distributed control network. A network operating controller coordinates the operation of the network, including power distribution. At least one, but more typically two to five, wires interconnect all the controllers through one or more joints. Motor sensors and external world sensors monitor operating parameters of the robotic hand. The electrical signal output of the sensors can be input anywhere on the distributed control network. V-grooves on the robotic hand locate objects precisely and assist in gripping. The hand is sealed, immersible and has electrical connections through the rotary joints for anodizing in a single dunk without masking. In various forms, this intelligent, self-contained, dexterous hand, or combinations of such hands, can perform a wide variety of object gripping and manipulating tasks, as well as locomotion and combinations of locomotion and gripping.

Transcranial direct current stimulation over multiple days enhances motor performance of a grip task.

PubMed

Fan, Julie; Voisin, Julien; Milot, Marie-Hélène; Higgins, Johanne; Boudrias, Marie-Hélène

2017-09-01

Recovery of handgrip is critical after stroke since it is positively related to upper limb function. To boost motor recovery, transcranial direct current stimulation (tDCS) is a promising, non-invasive brain stimulation technique for the rehabilitation of persons with stroke. When applied over the primary motor cortex (M1), tDCS has been shown to modulate neural processes involved in motor learning. However, no studies have looked at the impact of tDCS on the learning of a grip task in both stroke and healthy individuals. To assess the use of tDCS over multiple days to promote motor learning of a grip task using a learning paradigm involving a speed-accuracy tradeoff in healthy individuals. In a double-blinded experiment, 30 right-handed subjects (mean age: 22.1±3.3 years) participated in the study and were randomly assigned to an anodal (n=15) or sham (n=15) stimulation group. First, subjects performed the grip task with their dominant hand while following the pace of a metronome. Afterwards, subjects trained on the task, at their own pace, over 5 consecutive days while receiving sham or anodal tDCS over M1. After training, subjects performed de novo the metronome-assisted task. The change in performance between the pre and post metronome-assisted task was used to assess the impact of the grip task and tDCS on learning. Anodal tDCS over M1 had a significant effect on the speed-accuracy tradeoff function. The anodal tDCS group showed significantly greater improvement in performance (39.28±15.92%) than the sham tDCS group (24.06±16.35%) on the metronome-assisted task, t(28)=2.583, P=0.015 (effect size d=0.94). Anodal tDCS is effective in promoting grip motor learning in healthy individuals. Further studies are warranted to test its potential use for the rehabilitation of fine motor skills in stroke patients. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Finger-attachment device for the feedback of gripping and pulling force in a manipulating system for brain tumor resection.

PubMed

Chinbe, Hiroyuki; Yoneyama, Takeshi; Watanabe, Tetsuyou; Miyashita, Katsuyoshi; Nakada, Mitsutoshi

2018-01-01

Development and evaluation of an effective attachment device for a bilateral brain tumor resection robotic surgery system based on the sensory performance of the human index finger in order to precisely detect gripping- and pulling-force feedback. First, a basic test was conducted to investigate the performance of the human index finger in the gripping- and pulling-force feedback system. Based on the test result, a new finger-attachment device was designed and constructed. Then, discrimination tests were conducted to assess the pulling force and the feedback on the hardness of the gripped material. The results of the basic test show the application of pulling force on the side surface of the finger has an advantage to distinguish the pulling force when the gripping force is applied on the finger-touching surface. Based on this result, a finger-attachment device that applies a gripping force on the finger surface and pulling force on the side surface of the finger was developed. By conducting a discrimination test to assess the hardness of the gripped material, an operator can distinguish whether the gripped material is harder or softer than a normal brain tissue. This will help in confirming whether the gripped material is a tumor. By conducting a discrimination test to assess the pulling force, an operator can distinguish the pulling-force resistance when attempting to pull off the soft material. Pulling-force feedback may help avoid the breaking of blood pipes when they are trapped in the gripper or attached to the gripped tissue. The finger-attachment device that was developed for detecting gripping- and pulling-force feedback may play an important role in the development of future neurosurgery robotic systems for precise and safe resection of brain tumors.

Aging enhances serum cytokine response but not task-induced grip strength declines in a rat model of work-related musculoskeletal disorders

PubMed Central

2011-01-01

Background We previously reported early tissue injury, increased serum and tissue inflammatory cytokines and decreased grip in young rats performing a moderate demand repetitive task. The tissue cytokine response was transient, the serum response and decreased grip were still evident by 8 weeks. Thus, here, we examined their levels at 12 weeks in young rats. Since aging is known to enhance serum cytokine levels, we also examined aged rats. Methods Aged and young rats, 14 mo and 2.5 mo of age at onset, respectfully, were trained 15 min/day for 4 weeks, and then performed a high repetition, low force (HRLF) reaching and grasping task for 2 hours/day, for 12 weeks. Serum was assayed for 6 cytokines: IL-1alpha, IL-6, IFN-gamma, TNF-alpha, MIP2, IL-10. Grip strength was assayed, since we have previously shown an inverse correlation between grip strength and serum inflammatory cytokines. Results were compared to naïve (grip), and normal, food-restricted and trained-only controls. Results Serum cytokines were higher overall in aged than young rats, with increases in IL-1alpha, IFN-gamma and IL-6 in aged Trained and 12-week HRLF rats, compared to young Trained and HRLF rats (p < 0.05 and p < 0.001, respectively, each). IL-6 was also increased in aged 12-week HRLF versus aged normal controls (p < 0.05). Serum IFN-gamma and MIP2 levels were also increased in young 6-week HRLF rats, but no cytokines were above baseline levels in young 12-week HRLF rats. Grip strength declined in both young and aged 12-week HRLF rats, compared to naïve and normal controls (p < 0.05 each), but these declines correlated only with IL-6 levels in aged rats (r = -0.39). Conclusion Aging enhanced a serum cytokine response in general, a response that was even greater with repetitive task performance. Grip strength was adversely affected by task performance in both age groups, but was apparently influenced by factors other than serum cytokine levels in young rats. PMID:21447183

The development of tool use: Planning for end-state comfort

PubMed Central

Comalli, David M.; Keen, Rachel; Abraham, Evelyn S.; Foo, Victoria J.; Lee, Mei-Hua; Adolph, Karen E.

2016-01-01

Some grips on the handle of a tool can be planned based on information directly available in the scene. Other grips, however, must be planned based on the final position of the hand. “End-state comfort” grips require an awkward or uncomfortable initial grip so as to later implement the action comfortably and efficiently. From a cognitive perspective, planning for end-state comfort requires a consistent representation of the entire action sequence, including the latter part, which is not based on information directly available in the scene. Many investigators have found that young children fail to demonstrate planning for end-state comfort and that adult-like performance does not appear until about 12 years of age. In two experiments, we used a hammering task that engaged children in a goal-directed action with multiple steps. We assessed end-state-comfort planning in novel ways by measuring children’s hand choice, grip choice, and tool implementation over multiple trials. The hammering task also uniquely allowed us to assess the efficiency of implementation. We replicated the previous developmental trend in 4-, 8-, and 12-year-old children with our novel task. Most important, our data revealed that 4-year-olds are in a transitional stage with several competing strategies exhibited during a single session. Preschoolers changed their grip within trials and across trials, indicating awareness of errors and a willingness to sacrifice speed for more efficient implementation. The end-state-comfort grip initially competes as one grip type among many, but gradually displaces all others. Children’s sensitivity to and drive for efficiency may motivate this change. PMID:27786531

Control of Precision Grip Force in Lifting and Holding of Low-Mass Objects

PubMed Central

Kimura, Daisuke; Kadota, Koji; Ito, Taro

2015-01-01

Few studies have investigated the control of grip force when manipulating an object with an extremely small mass using a precision grip, although some related information has been provided by studies conducted in an unusual microgravity environment. Grip-load force coordination was examined while healthy adults (N = 17) held a moveable instrumented apparatus with its mass changed between 6 g and 200 g in 14 steps, with its grip surface set as either sandpaper or rayon. Additional measurements of grip-force-dependent finger-surface contact area and finger skin indentation, as well as a test of weight discrimination, were also performed. For each surface condition, the static grip force was modulated in parallel with load force while holding the object of a mass above 30 g. For objects with mass smaller than 30 g, on the other hand, the parallel relationship was changed, resulting in a progressive increase in grip-to-load force (GF/LF) ratio. The rayon had a higher GF/LF force ratio across all mass levels. The proportion of safety margin in the static grip force and normalized moment-to-moment variability of the static grip force were also elevated towards the lower end of the object mass for both surfaces. These findings indicate that the strategy of grip force control for holding objects with an extremely small mass differs from that with a mass above 30 g. The data for the contact area, skin indentation, and weight discrimination suggest that a decreased level of cutaneous feedback signals from the finger pads could have played some role in a cost function in efficient grip force control with low-mass objects. The elevated grip force variability associated with signal-dependent and internal noises, and anticipated inertial force on the held object due to acceleration of the arm and hand, could also have contributed to the cost function. PMID:26376484

Anticipatory scaling of grip forces when lifting objects of everyday life.

PubMed

Hermsdörfer, Joachim; Li, Yong; Randerath, Jennifer; Goldenberg, Georg; Eidenmüller, Sandra

2011-07-01

The ability to predict and anticipate the mechanical demands of the environment promotes smooth and skillful motor actions. Thus, the finger forces produced to grasp and lift an object are scaled to the physical properties such as weight. While grip force scaling is well established for neutral objects, only few studies analyzed objects known from daily routine and none studied grip forces. In the present study, eleven healthy subjects each lifted twelve objects of everyday life that encompassed a wide range of weights. The finger pads were covered with force sensors that enabled the measurement of grip force. A scale registered load forces. In a control experiment, the objects were wrapped into paper to prevent recognition by the subjects. Data from the first lift of each object confirmed that object weight was anticipated by adequately scaled forces. The maximum grip force rate during the force increase phase emerged as the most reliable measure to verify that weight was actually predicted and to characterize the precision of this prediction, while other force measures were scaled to object weight also when object identity was not known. Variability and linearity of the grip force-weight relationship improved for time points reached after liftoff, suggesting that sensory information refined the force adjustment. The same mechanism seemed to be involved with unrecognizable objects, though a lower precision was reached. Repeated lifting of the same object within a second and third presentation block did not improve the precision of the grip force scaling. Either practice was too variable or the motor system does not prioritize the optimization of the internal representation when objects are highly familiar.

Computational model of precision grip in Parkinson's disease: a utility based approach

PubMed Central

Gupta, Ankur; Balasubramani, Pragathi P.; Chakravarthy, V. Srinivasa

2013-01-01

We propose a computational model of Precision Grip (PG) performance in normal subjects and Parkinson's Disease (PD) patients. Prior studies on grip force generation in PD patients show an increase in grip force during ON medication and an increase in the variability of the grip force during OFF medication (Ingvarsson et al., 1997; Fellows et al., 1998). Changes in grip force generation in dopamine-deficient PD conditions strongly suggest contribution of the Basal Ganglia, a deep brain system having a crucial role in translating dopamine signals to decision making. The present approach is to treat the problem of modeling grip force generation as a problem of action selection, which is one of the key functions of the Basal Ganglia. The model consists of two components: (1) the sensory-motor loop component, and (2) the Basal Ganglia component. The sensory-motor loop component converts a reference position and a reference grip force, into lift force and grip force profiles, respectively. These two forces cooperate in grip-lifting a load. The sensory-motor loop component also includes a plant model that represents the interaction between two fingers involved in PG, and the object to be lifted. The Basal Ganglia component is modeled using Reinforcement Learning with the significant difference that the action selection is performed using utility distribution instead of using purely Value-based distribution, thereby incorporating risk-based decision making. The proposed model is able to account for the PG results from normal and PD patients accurately (Ingvarsson et al., 1997; Fellows et al., 1998). To our knowledge the model is the first model of PG in PD conditions. PMID:24348373

Influence of the type of training task on intermanual transfer effects in upper-limb prosthesis training: A randomized pre-posttest study.

PubMed

Romkema, Sietske; Bongers, Raoul M; van der Sluis, Corry K

2017-01-01

Intermanual transfer, the transfer of motor skills from the trained hand to the untrained hand, can be used to train upper limb prosthesis skills. The aim of this study was to determine the relation between the magnitude of the intermanual transfer effect and the type of training task. The used tasks were based on different aspects of prosthetic handling: reaching, grasping, grip-force production and functional tasks. A single-blinded clinical trial, with a pre-posttest design was executed. Seventy-one able-bodied, right-handed participants were randomly assigned to four training and two control groups. The training groups performed a training program with an upper-limb prosthesis simulator. One control group performed a sham training (a dummy training without the prosthesis simulator) and another control group received no training at all. The training groups and sham group trained on five consecutive days. To determine the improvement in skills, a test was administered before, immediately after, and one week after the training. Training was performed with the 'unaffected' arm; tests were performed with the 'affected' arm, with the latter resembling the amputated limb. In this study half of the participants trained with the dominant hand, while the other half trained with the non-dominant hand. Participants executed four tests that corresponded to the different training tasks. The tests measured the reaching (movement time and symmetry ratio), grasping (opening time, duration of maximum hand opening, and closing time), grip-force production (deviation of asked grip-force) and functional (movement time) performance. Half of the participants were tested with their dominant arm and half of the participants with their non-dominant arm. Intermanual transfer effects were not found for reaching, grasping or functional tasks. However, we did find intermanual transfer effects for grip-force production tasks. Possibly, the study design contributed to the negative results due to the duration of the training sessions and test sessions. The positive results of the grip-force production might be an effect of the specificity of the training, that was totally focused on training grip-force production. When using intermanual transfer training in novice amputees, specific training should be devoted to grip-force.

Influence of the type of training task on intermanual transfer effects in upper-limb prosthesis training: A randomized pre-posttest study

PubMed Central

Romkema, Sietske; Bongers, Raoul M.; van der Sluis, Corry K.

2017-01-01

Intermanual transfer, the transfer of motor skills from the trained hand to the untrained hand, can be used to train upper limb prosthesis skills. The aim of this study was to determine the relation between the magnitude of the intermanual transfer effect and the type of training task. The used tasks were based on different aspects of prosthetic handling: reaching, grasping, grip-force production and functional tasks. A single-blinded clinical trial, with a pre-posttest design was executed. Seventy-one able-bodied, right-handed participants were randomly assigned to four training and two control groups. The training groups performed a training program with an upper-limb prosthesis simulator. One control group performed a sham training (a dummy training without the prosthesis simulator) and another control group received no training at all. The training groups and sham group trained on five consecutive days. To determine the improvement in skills, a test was administered before, immediately after, and one week after the training. Training was performed with the ‘unaffected’ arm; tests were performed with the ‘affected’ arm, with the latter resembling the amputated limb. In this study half of the participants trained with the dominant hand, while the other half trained with the non-dominant hand. Participants executed four tests that corresponded to the different training tasks. The tests measured the reaching (movement time and symmetry ratio), grasping (opening time, duration of maximum hand opening, and closing time), grip-force production (deviation of asked grip-force) and functional (movement time) performance. Half of the participants were tested with their dominant arm and half of the participants with their non-dominant arm. Intermanual transfer effects were not found for reaching, grasping or functional tasks. However, we did find intermanual transfer effects for grip-force production tasks. Possibly, the study design contributed to the negative results due to the duration of the training sessions and test sessions. The positive results of the grip-force production might be an effect of the specificity of the training, that was totally focused on training grip-force production. When using intermanual transfer training in novice amputees, specific training should be devoted to grip-force. PMID:29190727

Precision grip responses to unexpected rotational perturbations scale with axis of rotation.

PubMed

De Gregorio, Michael; Santos, Veronica J

2013-04-05

It has been established that rapid, pulse-like increases in precision grip forces ("catch-up responses") are elicited by unexpected translational perturbations and that response latency and strength scale according to the direction of linear slip relative to the hand as well as gravity. To determine if catch-up responses are elicited by unexpected rotational perturbations and are strength-, axis-, and/or direction-dependent, we imposed step torque loads about each of two axes which were defined relative to the subject's hand: the distal-proximal axis away from and towards the subject's palm, and the grip axis which connects the two fingertips. Precision grip responses were dominated initially by passive mechanics and then by active, unimodal catch-up responses. First dorsal interosseous activity, marking the start of the catch-up response, began 71-89 ms after the onset of perturbation. The onset latency, shape, and duration (217-231 ms) of the catch-up response were not affected by the axis, direction, or magnitude of the rotational perturbation, while strength was scaled by axis of rotation and slip conditions. Rotations about the grip axis that tilted the object away from the palm and induced rotational slip elicited stronger catch-up responses than rotations about the distal-proximal axis that twisted the object between the digits. To our knowledge, this study is the first to investigate grip responses to unexpected torque loads and to show characteristic, yet axis-dependent, catch-up responses for conditions other than pure linear slip. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cortical activation during power grip task with pneumatic pressure gauge: an fMRI study

NASA Astrophysics Data System (ADS)

Mohamad, M.; Mardan, N. H.; Ismail, S. S.

2017-05-01

Aging is associated with a decline in cognitive and motor function. But, the relationships with motor performance are less well understood. In this study, functional magnetic resonance imaging (fMRI) was used to assess cortical activation in older adults. This study employed power grip task that utilised block paradigm consisted of alternate 30s rest and active. A visual cue was used to pace the hand grip movement that clenched a cylindrical rubber bulb connected with pressure pneumatic gauge that measure the pressure (Psi). The objective of this study is determined the brain areas activated during motor task and the correlation between percentage signal change of each motor area (BA 4 and 6) and hand grip pressure. Result showed there was a significant difference in mean percentage signal change in BA 4 and BA 6 in both hemispheres and negative correlation obtained in BA 4 and BA 6. These results indicate that a reduced ability in the motor networks contribute to age-related decline in motor performance.

Adaptive Force Control in Grasping as a Function of Level of Developmental Disability

ERIC Educational Resources Information Center

Sprague, R. L.; Deutsch, K. M.; Newell, K. M.

2009-01-01

Background: The adaptation to the task demands of grasping (grip mode and object mass) was investigated as a function of level of developmental disability. Methods: Subjects grasped objects of different grip widths and masses that were instrumented to record grip forces. Results: Proportionally, fewer participants from the profound compared with…

Design of a surgical robot with dynamic vision field control for Single Port Endoscopic Surgery.

PubMed

Kobayashi, Yo; Sekiguchi, Yuta; Tomono, Yu; Watanabe, Hiroki; Toyoda, Kazutaka; Konishi, Kozo; Tomikawa, Morimasa; Ieiri, Satoshi; Tanoue, Kazuo; Hashizume, Makoto; Fujie, Masaktsu G

2010-01-01

Recently, a robotic system was developed to assist Single Port Endoscopic Surgery (SPS). However, the existing system required a manual change of vision field, hindering the surgical task and increasing the degrees of freedom (DOFs) of the manipulator. We proposed a surgical robot for SPS with dynamic vision field control, the endoscope view being manipulated by a master controller. The prototype robot consisted of a positioning and sheath manipulator (6 DOF) for vision field control, and dual tool tissue manipulators (gripping: 5DOF, cautery: 3DOF). Feasibility of the robot was demonstrated in vitro. The "cut and vision field control" (using tool manipulators) is suitable for precise cutting tasks in risky areas while a "cut by vision field control" (using a vision field control manipulator) is effective for rapid macro cutting of tissues. A resection task was accomplished using a combination of both methods.

Effort, performance, and motivation: insights from robot-assisted training of human golf putting and rat grip strength.

PubMed

Duarte, Jaime E; Gebrekristos, Berkenesh; Perez, Sergi; Rowe, Justin B; Sharp, Kelli; Reinkensmeyer, David J

2013-06-01

Robotic devices can modulate success rates and required effort levels during motor training, but it is unclear how this affects performance gains and motivation. Here we present results from training unimpaired humans in a virtual golf-putting task, and training spinal cord injured (SCI) rats in a grip strength task using robotically modulated success rates and effort levels. Robotic assistance in golf practice increased trainees feelings of competence, and, paradoxically, increased their sense effort, even though it had mixed effects on learning. Reducing effort during a grip strength training task led rats with SCI to practice the task more frequently. However, the more frequent practice of these rats did not cause them to exceed the strength gains achieved by rats that exercised less often at higher required effort levels. These results show that increasing success and decreasing effort with robots increases motivation, but has mixed effects on performance gains.

Grip force regulation during pinch grip lifts under somatosensory guidance: comparison between people with stroke and healthy controls.

PubMed

Blennerhassett, Jannette M; Carey, Leeanne M; Matyas, Thomas A

2006-03-01

To compare the timing and grip force application in a pinch grip task performed under somatosensory guidance in stroke and matched controls and to identify characteristics of impaired grip force regulation after stroke. Matched-pairs control group. University research laboratory. Forty-five people with stroke who could pick up a pen lid using a pinch grip and actively participated in rehabilitation and 45 adults without neurologic conditions or musculoskeletal or skin impairments affecting the hand, matched for age, sex, and hand dominance. Not applicable. Timing and magnitude of grip forces applied during pinch grip lift and hold. Prolonged time to grip and lift objects, and excessive grip force prior to commencing the lift occurred in approximately half of the contralesional (involved) hands of people with stroke. Fluctuating irregular forces and reduced adaptation of the grip safety margin were also observed. Excessive safety margins were not predominant after stroke. Extreme slowing and disorganized sequencing of the grip and lifting forces and difficulty maintaining a stable grip characterized severe dysfunction. Delayed grip formulation and variable grip force application are key characteristics of grip dysfunction after stroke.

Impact of novel shift handle laparoscopic tool on wrist ergonomics and task performance

PubMed Central

Yu, Denny; Lowndes, Bethany; Morrow, Missy; Kaufman, Kenton; Bingener, Juliane; Hallbeck, Susan

2015-01-01

Background Laparoscopic tool handles causing wrist flexion and extension more than 15° from neutral are considered “at-risk” for musculoskeletal strain. Therefore this study measured the impact of laparoscopic tool handle angles on wrist postures and task performance. Methods Eight surgeons performed standard and modified Fundamentals of Laparoscopic Surgery (FLS) tasks with laparoscopic tools. Tool A had three adjustable handle angle configurations, i.e., in-line 0° (A0), 30° (A30), and pistol-grip 70° (A70). Tool B was a fixed pistol-grip grasper. Participants performed FLS peg transfer, inverted peg transfer, and inverted circle-cut with each tool and handle angle. Inverted tasks were adapted from standard FLS tasks to simulate advanced tasks observed during abdominal wall surgeries, e.g., ventral hernia. Motion tracking, video-analysis, and modified NASA-TLX workload questionnaires were used to measure postures, performance (e.g., completion time and errors), and workload. Results Task performance did not differ among tools. For FLS peg transfer, self-reported physical workload was lower for B than A70, and mean wrist postures showed significantly higher flexion for in-line than pistol-grip tools (B and A70). For inverted peg transfer, workload was higher for all configurations. However, less time was spent in at-risk wrist postures for in-line (47%) than pistol-grip (93-94%), and most participants preferred Tool A. For inverted circle cut, workload did not vary across configurations, mean wrist posture was 10° closer to neutral for A0 than B, and median time in at-risk wrist postures was significantly less for A0 (43%) than B (87%). Conclusion The best ergonomic wrist positions for FLS (floor) tasks are provided by pistol-grip tools and for tasks on the abdominal wall (ventral surface) by in-line handles. Adjustable handle angle laparoscopic tools can reduce ergonomic risks for musculoskeletal strain and allow versatility for tasks alternating between the floor and ceiling positions in a surgical trainer without impacting performance. PMID:26541720

Impact of novel shift handle laparoscopic tool on wrist ergonomics and task performance.

PubMed

Yu, Denny; Lowndes, Bethany; Morrow, Missy; Kaufman, Kenton; Bingener, Juliane; Hallbeck, Susan

2016-08-01

Laparoscopic tool handles causing wrist flexion and extension more than 15° from neutral are considered "at risk" for musculoskeletal strain. Therefore, this study measured the impact of laparoscopic tool handle angles on wrist postures and task performance. Eight surgeons performed standard and modified Fundamentals of Laparoscopic Surgery (FLS) tasks with laparoscopic tools. Tool A had three adjustable handle angle configurations, i.e., in-line 0° (A0), 30° (A30), and pistol-grip 70° (A70). Tool B was a fixed pistol-grip grasper. Participants performed FLS peg transfer, inverted peg transfer, and inverted circle cut with each tool and handle angle. Inverted tasks were adapted from standard FLS tasks to simulate advanced tasks observed during abdominal wall surgeries, e.g., ventral hernia. Motion tracking, video analysis, and modified NASA-TLX workload questionnaires were used to measure postures, performance (e.g., completion time and errors), and workload. Task performance did not differ between tools. For FLS peg transfer, self-reported physical workload was lower for B than for A70, and mean wrist postures showed significantly higher flexion for in-line than for pistol-grip tools (B and A70). For inverted peg transfer, workload was higher for all configurations. However, less time was spent in at-risk wrist postures for in-line (47 %) than for pistol-grip (93-94 %), and most participants preferred Tool A. For inverted circle cut, workload did not vary across configurations, mean wrist posture was 10° closer to neutral for A0 than B, and median time in at-risk wrist postures was significantly less for A0 (43 %) than for B (87 %). The best ergonomic wrist positions for FLS (floor) tasks are provided by pistol-grip tools and for tasks on the abdominal wall (ventral surface) by in-line handles. Adjustable handle angle laparoscopic tools can reduce ergonomic risks of musculoskeletal strain and allow versatility for tasks alternating between the floor and ceiling positions in a surgical trainer without impacting performance.

Muscular activity of different shooting distances, different release techniques, and different performance levels, with and without stabilizers, in target archery.

PubMed

Clarys, J P; Cabri, J; Bollens, E; Sleeckx, R; Taeymans, J; Vermeiren, M; Van Reeth, G; Voss, G

1990-01-01

The quadruple approach in the title refers to four different studies over a period of 3 years. The common factor in these studies is the methodology of the (Brussels) Electromyographic Signal Processing and Analysis System (ESPAS), a hardware and software EMG data acquisition system that has constantly been improved. Therefore, the ESPAS methodology is described extensively (i.e. the electrodes, amplifier, tape-recorder and processing hardware). Experiment 1 investigated muscular behaviour in target shooting, both indoors (18 and 25 m) and outdoors (50, 70 and 90 m). It was found (via iEMG) that a significant increase in activity only exists between 25 and 50 m, and that there is no linear increase of activity with increased distance. No differences in muscular pattern (IDANCO system: Clarys and Cabri, 1988) or activity between the indoor distances and between the outdoor distances were found. Experiment 2 investigated the muscular economy of four string grips: the three-finger grip, two-finger grip, thumb grip and reversed grip. The largest variations in activity were found for the two most unfamiliar grips, i.e. the thumb and reversed grips; however, low iEMG and the rapid precision improvement (over a limited number of shots) suggest that the thumb grip, if practised long enough, might be the most economical technique. Experiment 3 attempted to differentiate muscular activity and a number of performance variables in three different populations of archers--Olympic athletes, National competitors and beginners--in order to obtain feedback regarding improved performance. Apparently, overall muscle pattern, intensities and arrow speed were not discriminatory. The differences found between the groups (or levels of skill) were affected by the ability to reproduce identical patterns and arrow velocities in consecutive shots and by the constancy of neuromuscular control of the M. trapezius, M. biceps brachii and M. extensor digitorum. Finally, Experiment 4 investigated the muscular activity of elite archers shooting at distances of 70 and 90 m with and without stabilizers. Differences in iEMG were not supported by differences in precision. Over time, the low iEMG in shooting without stabilizers increases precision and delays fatigue.

On the evolution of handedness: evidence for feeding biases.

PubMed

Flindall, Jason W; Gonzalez, Claudia L R

2013-01-01

Many theories have been put forward to explain the origins of right-handedness in humans. Here we present evidence that this preference may stem in part from a right hand advantage in grasping for feeding. Thirteen participants were asked to reach-to-grasp food items of 3 different sizes: SMALL (Cheerios®), MEDIUM (Froot Loops®), and LARGE (Oatmeal Squares®). Participants used both their right- and left-hands in separate blocks (50 trials each, starting order counterbalanced) to grasp the items. After each grasp, participants either a) ate the food item, or b) placed it inside a bib worn beneath his/her chin (25 trials each, blocked design, counterbalanced). The conditions were designed such that the outward and inward movement trajectories were similar, differing only in the final step of placing it in the mouth or bib. Participants wore Plato liquid crystal goggles that blocked vision between trials. All trials were conducted in closed-loop with 5000 ms of vision. Hand kinematics were recorded by an Optotrak Certus, which tracked the position of three infrared diodes attached separately to the index finger, thumb, and wrist. We found a task (EAT/PLACE) by hand (LEFT/RIGHT) interaction on maximum grip aperture (MGA; the maximum distance between the index finger and thumb achieved during grasp pre-shaping). MGAs were smaller during right-handed movements, but only when grasping with intent to eat. Follow-up tests show that the RIGHT-HAND/EAT MGA was significantly smaller than all other hand/task conditions. Because smaller grip apertures are typically associated with greater precision, our results demonstrate a right-hand advantage for the grasp-to-eat movement. From an evolutionary perspective, early humans may have preferred the hand that could grasp food with more precision, thereby maximizing the likelihood of retrieval, consumption, and consequently, survival.

The end-state comfort effect in bimanual grip selection.

PubMed

Fischman, Mark G; Stodden, David F; Lehman, Davana M

2003-03-01

During a unimanual grip selection task in which people pick up a lightweight dowel and place one end against targets at variable heights, the choice of hand grip (overhand vs. underhand) typically depends on the perception of how comfortable the arm will be at the end of the movement: an end-state comfort effect. The two experiments reported here extend this work to bimanual tasks. In each experiment, 26 right-handed participants used their left and right hands to simultaneously pick up two wooden dowels and place either the right or left end against a series of 14 targets ranging from 14 to 210 cm above the floor. These tasks were performed in systematic ascending and descending orders in Experiment 1 and in random order in Expiment 2. Results were generally consistent with predictions of end-state comfort in that, for the extreme highest and lowest targets, participants tended to select opposite grips with each hand. Taken together, our findings are consistent with the concept of constraint hierarchies within a posture-based motion-planning model.

Writing Forces Associated With Four Pencil Grasp Patterns in Grade 4 Children

PubMed Central

Schwellnus, Heidi; Carnahan, Heather; Kushki, Azadeh; Polatajko, Helene; Missiuna, Cheryl

2013-01-01

OBJECTIVE. We investigated differences in handwriting kinetics, speed, and legibility among four pencil grasps after a 10-min copy task. METHOD. Seventy-four Grade 4 students completed a handwriting assessment before and after a copy task. Grip and axial forces were measured with an instrumented stylus and force-sensitive tablet. We used multiple linear regression to analyze the relationship between grasp pattern and grip and axial forces. RESULTS. We found no kinetic differences among grasps, whether considered individually or grouped by the number of fingers on the barrel. However, when grasps were grouped according to the thumb position, the adducted grasps exhibited higher mean grip and axial forces. CONCLUSION. Grip forces were generally similar across the different grasps. Kinetic differences resulting from thumb position seemed to have no bearing on speed and legibility. Interventions for handwriting difficulties should focus more on speed and letter formation than on grasp pattern. PMID:23433277

Processing of probabilistic information in weight perception and motor prediction.

PubMed

Trampenau, Leif; van Eimeren, Thilo; Kuhtz-Buschbeck, Johann

2017-02-01

We studied the effects of probabilistic cues, i.e., of information of limited certainty, in the context of an action task (GL: grip-lift) and of a perceptual task (WP: weight perception). Normal subjects (n = 22) saw four different probabilistic visual cues, each of which announced the likely weight of an object. In the GL task, the object was grasped and lifted with a pinch grip, and the peak force rates indicated that the grip and load forces were scaled predictively according to the probabilistic information. The WP task provided the expected heaviness related to each probabilistic cue; the participants gradually adjusted the object's weight until its heaviness matched the expected weight for a given cue. Subjects were randomly assigned to two groups: one started with the GL task and the other one with the WP task. The four different probabilistic cues influenced weight adjustments in the WP task and peak force rates in the GL task in a similar manner. The interpretation and utilization of the probabilistic information was critically influenced by the initial task. Participants who started with the WP task classified the four probabilistic cues into four distinct categories and applied these categories to the subsequent GL task. On the other side, participants who started with the GL task applied three distinct categories to the four cues and retained this classification in the following WP task. The initial strategy, once established, determined the way how the probabilistic information was interpreted and implemented.

Priming Hand Motor Training with Repetitive Stimulation of the Fingertips; Performance Gain and Functional Imaging of Training Effects.

PubMed

Lotze, Martin; Ladda, Aija Marie; Roschka, Sybille; Platz, Thomas; Dinse, Hubert R

Application of repetitive electrical stimulation (rES) of the fingers has been shown to improve tactile perception and sensorimotor performance in healthy individuals. To increase motor performance by priming the effects of active motor training (arm ability training; AAT) using rES. We compared the performance gain for the training increase of the averaged AAT tasks of both hands in two groups of strongly right-handed healthy volunteers. Functional Magnetic Resonance Imaging (fMRI) before and after AAT was assessed using three tasks for each hand separately: finger sequence tapping, visually guided grip force modulation, and writing. Performance during fMRI was controlled for preciseness and frequency. A total of 30 participants underwent a two-week unilateral left hand AAT, 15 participants with 20 minutes of rES priming of all fingertips of the trained hand, and 15 participants without rES priming. rES-primed AAT improved the trained left-hand performance across all training tasks on average by 32.9%, non-primed AAT improved by 29.5%. This gain in AAT performance with rES priming was predominantly driven by an increased finger tapping velocity. Functional imaging showed comparable changes for both training groups over time. Across all participants, improved AAT performance was associated with a higher contralateral primary somatosensory cortex (S1) fMRI activation magnitude during the grip force modulation task. This study highlights the importance of S1 for hand motor training gain. In addition, it suggests the usage of rES of the fingertips for priming active hand motor training. Copyright © 2016 Elsevier Inc. All rights reserved.

The role of tactile feedback in grip force during laparoscopic training tasks.

PubMed

Wottawa, Christopher R; Cohen, Jeremiah R; Fan, Richard E; Bisley, James W; Culjat, Martin O; Grundfest, Warren S; Dutson, Erik P

2013-04-01

Laparoscopic minimally invasive surgery has revolutionized surgical care by reducing trauma to the patient, thereby decreasing the need for medication and shortening recovery times. During open procedures, surgeons can directly feel tissue characteristics. However, in laparoscopic surgery, tactile feedback during grip is attenuated and limited to the resistance felt in the tool handle. Excessive grip force during laparoscopic surgery can lead to tissue damage. Providing additional supplementary tactile feedback may allow subjects to have better control of grip force and identification of tissue characteristics, potentially decreasing the learning curve associated with complex minimally invasive techniques. A tactile feedback system has been developed and integrated into a modified laparoscopic grasper that allows forces applied at the grasper tips to be felt by the surgeon's hands. In this study, 15 subjects (11 novices, 4 experts) were asked to perform single-handed peg transfers using these laparoscopic graspers in three trials (feedback OFF, ON, OFF). Peak and average grip forces (newtons) during each grip event were measured and compared using a Wilcoxon ranked test in which each subject served as his or her own control. After activating the tactile feedback system, the novice subject population showed significant decreases in grip force (p < 0.003). When the system was deactivated for the third trial, there were significant increases in grip force (p < 0.003). Expert subjects showed no significant improvements with the addition of tactile feedback (p > 0.05 in all cases). Supplementary tactile feedback helped novice subjects reduce grip force during the laparoscopic training task but did not offer improvements for the four expert subjects. This indicates that tactile feedback may be beneficial for laparoscopic training but has limited long-term use in the nonrobotic setting.

Kinematic characteristics of tenodesis grasp in C6 quadriplegia.

PubMed

Mateo, S; Revol, P; Fourtassi, M; Rossetti, Y; Collet, C; Rode, G

2013-02-01

Descriptive control case study. To analyze the kinematics of tenodesis grasp in participants with C6 quadriplegia and healthy control participants in a pointing task and two daily life tasks involving a whole hand grip (apple) or a lateral grip (floppy disk). France. Four complete participants with C6 quadriplegia were age matched with four healthy control participants. All participants were right-handed. The measured kinematic parameters were the movement time (MT), the peak velocity (PV), the time of PV (TPV) and the wrist angle in the sagittal plane at movement onset, at the TPV and at the movement end point. The participants with C6 quadriplegia had significantly longer MTs in both prehension tasks. No significant differences in TPV were found between the two groups. Unlike control participants, for both prehension tasks the wrist of participants with C6 quadriplegia was in a neutral position at movement onset, in flexion at the TPV, and in extension at the movement end point. Two main kinematic parameters characterize tenodesis grasp movements in C6 quadriplegics: wrist flexion during reaching and wrist extension during the grasping phase, and increased MT reflecting the time required to adjust the wrist's position to achieve the tenodesis grasp. These characteristics were observed for two different grips (whole hand and lateral grip). These results suggest sequential planning of reaching and tenodesis grasp, and should be taken into account for prehension rehabilitation in patients with quadriplegia.

Flexible Electrostatic Technologies for Capture and Handling, Phase 1

NASA Technical Reports Server (NTRS)

Bryan, Thomas

2015-01-01

Fundamental to many of NASA's in-space transportation missions is the capture and handling of various objects and vehicles in various orbits for servicing, debris disposal, sample retrieval, and assembly without the benefit of sufficient grapple fixtures and docking ports. To perform similar material handling tasks on Earth, pincher grippers, suction grippers, or magnetic chucks are used, but are unable to reliably grip aluminum and composite spacecraft, insulation, radiators, solar arrays, or extra-terrestrial objects in the vacuum of outer space without dedicated handles in the right places. The electronic Flexible Electrostatic Technologies for space Capture and Handling (FETCH) will enable reliable and compliant gripping (soft dock) of practically any object in various orbits or surfaces without dedicated mechanical features, very low impact capture, and built-in proximity sensing without any conventional actuators. Originally developed to handle semiconductor and glass wafers during vacuum chamber processing without contamination, the normal rigid wafer handling chucks are replaced with thin metal foil segments laminated in flexible insulation driven by commercial off-the-shelf solid state, high-voltage power supplies. Preliminary testing in NASA Marshall Space Flight Center's (MSFC's) Flat Floor Robotics Lab demonstrated compliant alignment and gripping with a full-sized, 150-lb microsat mockup and translation before a clean release with a flip of a switch. The flexible electrostatic gripper pads can be adapted to various space applications with different sizes, shapes, and foil electrode layouts even with openings through the gripper pads for addition of guidance sensors or injection of permanent adhesives. With gripping forces estimated between 0.5 and 2.5 lb/in2 or 70-300 lb/ft2 of surface contact, the FETCH can turn on and off rapidly and repeatedly to enable sample handling, soft docking, in-space assembly, precision relocation, and surface translation for accurate anchoring.

Grip force coordination during bimanual tasks in unilateral cerebral palsy.

PubMed

Islam, Mominul; Gordon, Andrew M; Sköld, Annika; Forssberg, Hans; Eliasson, Ann-Christin

2011-10-01

The aim of the study was to investigate coordination of fingertip forces during an asymmetrical bimanual task in children with unilateral cerebral palsy (CP). Twelve participants (six males, six females; mean age 14y 4mo, SD 3.3y; range 9-20y;) with unilateral CP (eight right-sided, four left-sided) and 15 age-matched typically developing participants (five males, 10 females; mean age 14y 3mo, SD 2.9y; range 9-18y,) were included. Participants were instructed to hold custom-made grip devices in each hand and place one device on top of the other. The grip force and load force were recorded simultaneously in both hands. Temporal coordination between the two hands was impaired in the participants with CP (compared with that in typically developing participants), that is they initiated the task by decreasing grip force in the releasing hand before increasing the force in the holding hand. The grip force increase in the holding hand was also smaller in participants with CP (involved hand/non-dominant hand releasing, p<0.001; non-involved hand/dominant hand releasing, p=0.007), indicating deficient scaling of force amplitude. The impairment was greater when participants with CP used their non-involved hand as the holding hand. Temporal coordination and scaling of fingertip forces were impaired in both hands in participants with CP. The non-involved hand was strongly affected by activity in the involved hand, which may explain why children with unilateral CP prefer to use only one hand during tasks that are typically performed with both hands. © The Authors. Developmental Medicine & Child Neurology © 2011 Mac Keith Press.

Conflict in object affordance revealed by grip force

PubMed Central

McBride, Jennifer; Sumner, Petroc; Husain, Masud

2011-01-01

Viewing objects can result in automatic, partial activation of motor plans associated with them—“object affordance”. Here, we recorded grip force simultaneously from both hands in an object affordance task to investigate the effects of conflict between coactivated responses. Participants classified pictures of objects by squeezing force transducers with their left or right hand. Responses were faster on trials where the object afforded an action with the same hand that was required to make the response (congruent trials) compared to the opposite hand (incongruent trials). In addition, conflict between coactivated responses was reduced if it was experienced on the preceding trial, just like Gratton adaptation effects reported in “conflict” tasks (e.g., Eriksen flanker). This finding suggests that object affordance demonstrates conflict effects similar to those shown in other stimulus–response mapping tasks and thus could be integrated into the wider conceptual framework on overlearnt stimulus–response associations. Corrected erroneous responses occurred more frequently when there was conflict between the afforded response and the response required by the task, providing direct evidence that viewing an object activates motor plans appropriate for interacting with that object. Recording continuous grip force, as here, provides a sensitive way to measure coactivated responses in affordance tasks. PMID:21824035

Effects of Grip-Force, Contact, and Acceleration Feedback on a Teleoperated Pick-and-Place Task.

PubMed

Khurshid, Rebecca P; Fitter, Naomi T; Fedalei, Elizabeth A; Kuchenbecker, Katherine J

2017-01-01

The multifaceted human sense of touch is fundamental to direct manipulation, but technical challenges prevent most teleoperation systems from providing even a single modality of haptic feedback, such as force feedback. This paper postulates that ungrounded grip-force, fingertip-contact-and-pressure, and high-frequency acceleration haptic feedback will improve human performance of a teleoperated pick-and-place task. Thirty subjects used a teleoperation system consisting of a haptic device worn on the subject's right hand, a remote PR2 humanoid robot, and a Vicon motion capture system to move an object to a target location. Each subject completed the pick-and-place task 10 times under each of the eight haptic conditions obtained by turning on and off grip-force feedback, contact feedback, and acceleration feedback. To understand how object stiffness affects the utility of the feedback, half of the subjects completed the task with a flexible plastic cup, and the others used a rigid plastic block. The results indicate that the addition of grip-force feedback with gain switching enables subjects to hold both the flexible and rigid objects more stably, and it also allowed subjects who manipulated the rigid block to hold the object more delicately and to better control the motion of the remote robot's hand. Contact feedback improved the ability of subjects who manipulated the flexible cup to move the robot's arm in space, but it deteriorated this ability for subjects who manipulated the rigid block. Contact feedback also caused subjects to hold the flexible cup less stably, but the rigid block more securely. Finally, adding acceleration feedback slightly improved the subject's performance when setting the object down, as originally hypothesized; interestingly, it also allowed subjects to feel vibrations produced by the robot's motion, causing them to be more careful when completing the task. This study supports the utility of grip-force and high-frequency acceleration feedback in teleoperation systems and motivates further improvements to fingertip-contact-and-pressure feedback.

Writing forces associated with four pencil grasp patterns in grade 4 children.

PubMed

Schwellnus, Heidi; Carnahan, Heather; Kushki, Azadeh; Polatajko, Helene; Missiuna, Cheryl; Chau, Tom

2013-01-01

OBJECTIVE. We investigated differences in handwriting kinetics, speed, and legibility among four pencil grasps after a 10-min copy task. METHOD. Seventy-four Grade 4 students completed a handwriting assessment before and after a copy task. Grip and axial forces were measured with an instrumented stylus and force-sensitive tablet. We used multiple linear regression to analyze the relationship between grasp pattern and grip and axial forces. RESULTS. We found no kinetic differences among grasps, whether considered individually or grouped by the number of fingers on the barrel. However, when grasps were grouped according to the thumb position, the adducted grasps exhibited higher mean grip and axial forces. CONCLUSION. Grip forces were generally similar across the different grasps. Kinetic differences resulting from thumb position seemed to have no bearing on speed and legibility. Interventions for handwriting difficulties should focus more on speed and letter formation than on grasp pattern. Copyright © 2013 by the American Occupational Therapy Association, Inc.

Real-time augmented feedback benefits robotic laparoscopic training.

PubMed

Judkins, Timothy N; Oleynikov, Dmitry; Stergiou, Nick

2006-01-01

Robotic laparoscopic surgery has revolutionized minimally invasive surgery for treatment of abdominal pathologies. However, current training techniques rely on subjective evaluation. There is a lack of research on the type of tasks that should be used for training. Robotic surgical systems also do not currently have the ability to provide feedback to the surgeon regarding success of performing tasks. We trained medical students on three laparoscopic tasks and provided real-time feedback of performance during training. We found that real-time feedback can benefit training if the feedback provides information that is not available through other means (grip force). Subjects that received grip force feedback applied less force when the feedback was removed. Other forms of feedback (speed and relative phase) did not aid or impede training. Secondly, a relatively short training period (10 trials for each task) significantly improved most objective measures of performance. We also showed that robotic surgical performance can be quantitatively measured and evaluated. Providing grip force feedback can make the surgeon more aware of the forces being applied to delicate tissue during surgery.

Adjustment of gripping force by optical systems

NASA Astrophysics Data System (ADS)

Jalba, C. K.; Barz, C.

2018-01-01

With increasing automation, robotics also requires ever more intelligent solutions in the handling of various tasks. In this context, many grippers must also be re-designed. For this, they must always be adapted for different requirements. The equipment of the gripper systems with sensors should help to make the gripping process more intelligent. In order to achieve such objectives, optical systems can also be used. This work analyzes how the gripping force can be adjusted by means of an optical recognition. The result of this work is the creation of a connection between optical recognition, tolerances, gripping force and real-time control. In this way, algorithms can be created, with the aid of which robot grippers as well as other gripping systems become more intelligent.

Analysis of the pen pressure and grip force signal during basic drawing tasks: The timing and speed changes impact drawing characteristics.

PubMed

Gatouillat, Arthur; Dumortier, Antoine; Perera, Subashan; Badr, Youakim; Gehin, Claudine; Sejdić, Ervin

2017-08-01

Writing is a complex fine and trained motor skill, involving complex biomechanical and cognitive processes. In this paper, we propose the study of writing kinetics using three angles: the pen-tip normal force, the total grip force signal and eventually writing quality assessment. In order to collect writing kinetics data, we designed a sensor collecting these characteristics simultaneously. Ten healthy right-handed adults were recruited and were asked to perform four tasks: first, they were instructed to draw circles at a speed they considered comfortable; they then were instructed to draw circles at a speed they regarded as fast; afterwards, they repeated the comfortable task compelled to follow the rhythm of a metronome; and eventually they performed the fast task under the same timing constraints. Statistical differences between the tasks were computed, and while pen-tip normal force and total grip force signal were not impacted by the changes introduced in each task, writing quality features were affected by both the speed changes and timing constraint changes. This verifies the already-studied speed-accuracy trade-off and suggest the existence of a timing constraints-accuracy trade-off. Copyright © 2017 Elsevier Ltd. All rights reserved.

Second-order motor planning in children: insights from a cup-manipulation-task.

PubMed

Wunsch, Kathrin; Weiss, Daniel J; Schack, Thomas; Weigelt, Matthias

2015-07-01

The present study examined the development of anticipatory motor planning in an object manipulation task that has been used to successfully demonstrate motor planning in non-human primates (Weiss et al. in Psychol Sci 18:1063-1068, 2007). Seventy-five participants from four different age groups participated in a cup-manipulation task. One group was preschool children (average age of 5.1 years), two groups were primary school children (7.7 and 9.8 years old respectively) and the final group was comprised of adults. The experimental task entailed reaching for a plastic cup that was vertically suspended in an apparatus in either upright or inverted orientation, removing the cup by its stem and then retrieving a small toy from the inside of the cup. When the cup was inverted in the apparatus, evidence for anticipatory motor planning could be achieved by initially gripping the stem using an inverted (thumb-down) grip posture. We found that when the cup was in upright orientation, all participants reached for the cup using an upright grip (i.e., thumb-up posture). However, when the cup was inverted in the apparatus, only adults consistently used an inverted grasping posture, though the percentage of inverted grips among participants did increase with age. These results suggest a protracted development for anticipatory motor planning abilities in children. Surprisingly, the performance of adults on this task more closely resembles the performance of several nonhuman primate species as opposed to children even at approximately 10 years of age. We discuss how morphological constraints on flexibility may help account for these findings.

Note on performance of tapered grip tensile loading devices

NASA Technical Reports Server (NTRS)

Jones, M. H.; Brown, W. F., Jr.

1975-01-01

Alignment results are presented in terms of percent bending for a quick release, tapered grip, tensile loading device that has been proposed for testing sharply notched specimens of aluminum and magnesium alloys by a Task Group of the ASTM Committee E-24 on Fracture Testing of Metals. The results show that the bending introduced by the fixtures is strongly dependent on their relative rotational positions in respect to the loading rods which adapt them, to the tensile machine. For one set of tapered grips the highest bending was about 15%. Recommendations are made for improvement in the design of the tapered grips which should reduce the bending stresses substantially.

Age-related differences in finger force control are characterized by reduced force production.

PubMed

Vieluf, Solveig; Godde, Ben; Reuter, Eva-Maria; Voelcker-Rehage, Claudia

2013-01-01

It has been repeatedly shown that precise finger force control declines with age. The tasks and evaluation parameters used to reveal age-related differences vary between studies. In order to examine effects of task characteristics, young adults (18-25 years) and late middle-aged adults (55-65 years) performed precision grip tasks with varying speed and force requirements. Different outcome variables were used to evaluate age-related differences. Age-related differences were confirmed for performance accuracy (TWR) and variability (relative root mean square error, rRMSE). The task characteristics, however, influenced accuracy and variability in both age groups: Force modulation performance at higher speed was poorer than at lower speed and at fixed force levels than at force levels adjusted to the individual maximum forces. This effect tended to be stronger for older participants for the rRMSE. A curve fit confirmed the age-related differences for both spatial force tracking parameters (amplitude and intercept) and for one temporal parameter (phase shift), but not for the temporal parameter frequency. Additionally, matching the timing parameters of the sine wave seemed to be more important than matching the spatial parameters in both young adults and late middle-aged adults. However, the effect was stronger for the group of late middle-aged, even though maximum voluntary contraction was not significantly different between groups. Our data indicate that changes in the processing of fine motor control tasks with increasing age are caused by difficulties of late middle-aged adults to produce a predefined amount of force in a short time.

On the Evolution of Handedness: Evidence for Feeding Biases

PubMed Central

Flindall, Jason W.; Gonzalez, Claudia L. R.

2013-01-01

Many theories have been put forward to explain the origins of right-handedness in humans. Here we present evidence that this preference may stem in part from a right hand advantage in grasping for feeding. Thirteen participants were asked to reach-to-grasp food items of 3 different sizes: SMALL (Cheerios®), MEDIUM (Froot Loops®), and LARGE (Oatmeal Squares®). Participants used both their right- and left-hands in separate blocks (50 trials each, starting order counterbalanced) to grasp the items. After each grasp, participants either a) ate the food item, or b) placed it inside a bib worn beneath his/her chin (25 trials each, blocked design, counterbalanced). The conditions were designed such that the outward and inward movement trajectories were similar, differing only in the final step of placing it in the mouth or bib. Participants wore Plato liquid crystal goggles that blocked vision between trials. All trials were conducted in closed-loop with 5000 ms of vision. Hand kinematics were recorded by an Optotrak Certus, which tracked the position of three infrared diodes attached separately to the index finger, thumb, and wrist. We found a task (EAT/PLACE) by hand (LEFT/RIGHT) interaction on maximum grip aperture (MGA; the maximum distance between the index finger and thumb achieved during grasp pre-shaping). MGAs were smaller during right-handed movements, but only when grasping with intent to eat. Follow-up tests show that the RIGHT-HAND/EAT MGA was significantly smaller than all other hand/task conditions. Because smaller grip apertures are typically associated with greater precision, our results demonstrate a right-hand advantage for the grasp-to-eat movement. From an evolutionary perspective, early humans may have preferred the hand that could grasp food with more precision, thereby maximizing the likelihood of retrieval, consumption, and consequently, survival. PMID:24236078

Heuristic control of the Utah/MIT dextrous robot hand

NASA Technical Reports Server (NTRS)

Bass, Andrew H., Jr.

1987-01-01

Basic hand grips and sensor interactions that a dextrous robot hand will need as part of the operation of an EVA Retriever are analyzed. What is to be done with a dextrous robot hand is examined along with how such a complex machine might be controlled. It was assumed throughout that an anthropomorphic robot hand should perform tasks just as a human would; i.e., the most efficient approach to developing control strategies for the hand would be to model actual hand actions and do the same tasks in the same ways. Therefore, basic hand grips that human hands perform, as well as hand grip action were analyzed. It was also important to examine what is termed sensor fusion. This is the integration of various disparate sensor feedback paths. These feedback paths can be spatially and temporally separated, as well as, of different sensor types. Neural networks are seen as a means of integrating these varied sensor inputs and types. Basic heuristics of hand actions and grips were developed. These heuristics offer promise of control dextrous robot hands in a more natural and efficient way.

Preserved and impaired aspects of feed-forward grip force control after chronic somatosensory deafferentation.

PubMed

Hermsdörfer, J; Elias, Z; Cole, J D; Quaney, B M; Nowak, D A

2008-01-01

Although feed-forward mechanisms of grip force control are a prerequisite for skilled object manipulation, somatosensory feedback is essential to acquire, maintain, and adapt these mechanisms. Individuals with complete peripheral deafferentation provide the unique opportunity to study the function of the motor system deprived of somatosensory feedback. Two individuals (GL and IW) with complete chronic deafferentation of the trunk and limbs were tested during cyclic vertical movements of a hand-held object. Such movements induce oscillating loads that are typically anticipated by parallel modulations of the grip force. Load magnitude was altered by varying either the movement frequency or object weight. GL and IW employed excessive grip forces probably reflecting a compensatory mechanism. Despite this overall force increase, both deafferented participants adjusted their grip force level according to the load magnitude, indicating preserved scaling of the background grip force to physical demands. The dynamic modulation of the grip force with the load force was largely absent in GL, whereas in IW only slower movements were clearly affected. The authors hypothesize that the deafferented patients may have utilized visual and vestibular cues and/or an efferent copy of the motor command of the arm movement to scale the grip force level. Severely impaired grip force-load coupling in GL suggests that sensory information is important for maintaining a precise internal model of dynamic grip force control. However, comparably better performance in IW argues for the possibility that alternative cues can be used to trigger a residual internal model.

Deficits of anticipatory grip force control after damage to peripheral and central sensorimotor systems.

PubMed

Hermsdörfer, Joachim; Hagl, Elke; Nowak, Dennis A

2004-11-01

Healthy subjects adjust their grip force economically to the weight of a hand-held object. In addition, inertial loads, which arise from arm movements with the grasped object, are anticipated by parallel grip force modulations. Internal forward models have been proposed to predict the consequences of voluntary movements. Anesthesia of the fingers impairs grip force economy but the feedforward character of the grip force/load coupling is preserved. To further analyze the role of sensory input for internal forward models and to characterize the consequences of central nervous system damage for anticipatory grip force control, we measured grip force behavior in neurological patients. We tested a group of stroke patients with varying degrees of impaired fine motor control and sensory loss, a single patient with complete and permanent differentation from all tactile and proprioceptive input, and a group of patients with amyotrophic lateral sclerosis (ALS) that exclusively impairs the motor system without affecting sensory modalities. Increased grip forces were a common finding in all patients. Sensory deficits were a strong but not the only predictor of impaired grip force economy. The feedforward mode of grip force control was typically preserved in the stroke patients despite their central sensory deficits, but was severely disturbed in the patient with peripheral sensory deafferentation and in a minority of stroke patients. Moderate deficits of feedforward control were also obvious in ALS patients. Thus, the function of the internal forward model and the precision of grip force production may depend on a complex anatomical and functional network of sensory and motor structures and their interaction in time and space.

Robot-assisted microsurgical forceps with haptic feedback for transoral laser microsurgery.

PubMed

Deshpande, Nikhil; Chauhan, Manish; Pacchierotti, Claudio; Prattichizzo, Domenico; Caldwell, Darwin G; Mattos, Leonardo S

2016-08-01

In this paper, a novel, motorized, multi-degrees-of-freedom (DoF), microsurgical forceps tool is presented, which is based on a master-slave teleoperation architecture. The slave device is a 7-DoF manipulator with: (i) 6-DoF positioning and orientation, (ii) 1 open/close gripper DoF; and (iii) an integrated force/torque sensor for tissue grip-force measurement. The master device is a 7-DoF haptic interface which teleoperates the slave device, and provides haptic feedback in its gripper interface. The combination of the device and the surgeon interface replaces the manual, hand-held device providing easy-to-use and ergonomic tissue control, simplifying the surgical tasks. This makes the system suitable to real surgical scenarios in the operating room (OR). The performance of the system was analysed through the evaluation of teleoperation control and characterization of gripping force. The new system offers an overall positioning error of less than 400 μm demonstrating its safety and accuracy. Improved system precision, usability, and ergonomics point to the potential suitability of the device for the OR and its ability to advance haptic-feedback-enhanced transoral laser microsurgeries.

Differences in grip force control between young and late middle-aged adults.

PubMed

Zheng, Lianrong; Li, Kunyang; Wang, Qian; Chen, Wenhui; Song, Rong; Liu, Guanzheng

2017-09-01

Grip force control is a crucial function for human to guarantee the quality of life. To examine the effects of age on grip force control, 10 young adults and 11 late middle-aged adults participated in visually guided tracking tasks using different target force levels (25, 50, and 75% of the subject's maximal grip force). Multiple measures were used to evaluate the tracking performance during force rising phase and force maintenance phase. The measurements include the rise time, fuzzy entropy, mean force percentage, coefficient of variation, and target deviation ratio. The results show that the maximal grip force was significantly lower in the late middle-aged adults than in the young adults. The time of rising phase was systematically longer among late middle-aged adults. The fuzzy entropy is a useful indicator for quantitating the force variability of the grip force signal at higher force levels. These results suggest that the late middle-aged adults applied a compensatory strategy that allow allows for sufficient time to reach the required grip force and reduce the impact of the early and subtle degenerative changes in hand motor function.

Temperature dependency in motor skill learning.

PubMed

Immink, Maarten A; Wright, David L; Barnes, William S

2012-01-01

The present study investigated the role of temperature as a contextual condition for motor skill learning. Precision grip task training occurred while forearm cutaneous temperature was either heated (40-45 °C) or cooled (10-15 °C). At test, temperature was either reinstated or changed. Performance was comparable between training conditions while at test, temperature changes decreased accuracy, especially after hot training conditions. After cold training, temperature change deficits were only evident when concurrent force feedback was presented. These findings are the first evidence of localized temperature dependency in motor skill learning in humans. Results are not entirely accounted for by a context-dependent memory explanation and appear to represent an interaction of neuromuscular and sensory processes with the temperature present during training and test.

Key Insights into Hand Biomechanics: Human Grip Stiffness Can Be Decoupled from Force by Cocontraction and Predicted from Electromyography

PubMed Central

Höppner, Hannes; Große-Dunker, Maximilian; Stillfried, Georg; Bayer, Justin; van der Smagt, Patrick

2017-01-01

We investigate the relation between grip force and grip stiffness for the human hand with and without voluntary cocontraction. Apart from gaining biomechanical insight, this issue is particularly relevant for variable-stiffness robotic systems, which can independently control the two parameters, but for which no clear methods exist to design or efficiently exploit them. Subjects were asked in one task to produce different levels of force, and stiffness was measured. As expected, this task reveals a linear coupling between force and stiffness. In a second task, subjects were then asked to additionally decouple stiffness from force at these force levels by using cocontraction. We measured the electromyogram from relevant groups of muscles and analyzed the possibility to predict stiffness and force. Optical tracking was used for avoiding wrist movements. We found that subjects were able to decouple grip stiffness from force when using cocontraction on average by about 20% of the maximum measured stiffness over all force levels, while this ability increased with the applied force. This result contradicts the force–stiffness behavior of most variable-stiffness actuators. Moreover, we found the thumb to be on average twice as stiff as the index finger and discovered that intrinsic hand muscles predominate our prediction of stiffness, but not of force. EMG activity and grip force allowed to explain 72 ± 12% of the measured variance in stiffness by simple linear regression, while only 33 ± 18% variance in force. Conclusively the high signal-to-noise ratio and the high correlation to stiffness of these muscles allow for a robust and reliable regression of stiffness, which can be used to continuously teleoperate compliance of modern robotic hands. PMID:28588472

Interaction in planning vocalizations and grasping.

PubMed

Tiainen, Mikko; Tiippana, Kaisa; Vainio, Martti; Komeilipoor, Naeem; Vainio, Lari

2017-08-01

Previous studies have shown a congruency effect between manual grasping and syllable articulation. For instance, a power grip is associated with syllables whose articulation involves the tongue body and/or large mouth aperture ([kɑ]) whereas a precision grip is associated with articulations that involve the tongue tip and/or small mouth aperture ([ti]). Previously, this effect has been observed in manual reaction times. The primary aim of the current study was to investigate whether this congruency effect also takes place in vocal responses and to investigate involvement of action selection processes in the effect. The congruency effect was found in vocal and manual responses regardless of whether or not the syllable or grip was known a priori, suggesting that the effect operates with minimal or absent action selection processes. In addition, the effect was observed in vocal responses even when the grip was only prepared but not performed, suggesting that merely planning a grip response primes the corresponding articulatory response. These results support the view that articulation and grasping are processed in a partially overlapping network.

Two-phase strategy of controlling motor coordination determined by task performance optimality.

PubMed

Shimansky, Yury P; Rand, Miya K

2013-02-01

A quantitative model of optimal coordination between hand transport and grip aperture has been derived in our previous studies of reach-to-grasp movements without utilizing explicit knowledge of the optimality criterion or motor plant dynamics. The model's utility for experimental data analysis has been demonstrated. Here we show how to generalize this model for a broad class of reaching-type, goal-directed movements. The model allows for measuring the variability of motor coordination and studying its dependence on movement phase. The experimentally found characteristics of that dependence imply that execution noise is low and does not affect motor coordination significantly. From those characteristics it is inferred that the cost of neural computations required for information acquisition and processing is included in the criterion of task performance optimality as a function of precision demand for state estimation and decision making. The precision demand is an additional optimized control variable that regulates the amount of neurocomputational resources activated dynamically. It is shown that an optimal control strategy in this case comprises two different phases. During the initial phase, the cost of neural computations is significantly reduced at the expense of reducing the demand for their precision, which results in speed-accuracy tradeoff violation and significant inter-trial variability of motor coordination. During the final phase, neural computations and thus motor coordination are considerably more precise to reduce the cost of errors in making a contact with the target object. The generality of the optimal coordination model and the two-phase control strategy is illustrated on several diverse examples.

Space spider crane

NASA Technical Reports Server (NTRS)

Macconochie, Ian O. (Inventor); Mikulas, Martin M., Jr. (Inventor); Pennington, Jack E. (Inventor); Kinkead, Rebecca L. (Inventor); Bryan, Charles F., Jr. (Inventor)

1988-01-01

A space spider crane for the movement, placement, and or assembly of various components on or in the vicinity of a space structure is described. As permanent space structures are utilized by the space program, a means will be required to transport cargo and perform various repair tasks. A space spider crane comprising a small central body with attached manipulators and legs fulfills this requirement. The manipulators may be equipped with constant pressure gripping end effectors or tools to accomplish various repair tasks. The legs are also equipped with constant pressure gripping end effectors to grip the space structure. Control of the space spider crane may be achieved either by computer software or a remotely situated human operator, who maintains visual contact via television cameras mounted on the space spider crane. One possible walking program consists of a parallel motion walking program whereby the small central body alternatively leans forward and backward relative to end effectors.

Hand Strength, Handwriting, and Functional Skills in Children With Autism.

PubMed

Alaniz, Michele L; Galit, Eleanor; Necesito, Corina Isabel; Rosario, Emily R

2015-01-01

To establish hand strength development trends in children with autism and to investigate correlations between grip and pinch strength, components of handwriting, and functional activities in children with and without autism. Fifty-one children were divided into two groups: typically developing children and children on the autism spectrum. Each child completed testing for pinch and grip strength, handwriting legibility, pencil control, and independence in functional activities. The children with autism followed the same strength development trends as the typically developing children. Grip strength correlated with pencil control in both groups and with handwriting legibility in the typically developing children but not in the children with autism. Grip and pinch strength correlated with independence with functional activities in both groups. This study provides evidence that grip and pinch strength are important components in developing pencil control, handwriting legibility, and independence with functional fine motor tasks. Copyright © 2015 by the American Occupational Therapy Association, Inc.

Volitional and automatic control of the hand when reaching to grasp objects.

PubMed

Chen, Zhongting; Saunders, Jeffrey Allen

2018-06-01

When picking up an object, we tend to grasp at contact points that allow a stable grip. Recent studies have demonstrated that appropriate grasp points can be selected during an ongoing movement in response to unexpected perturbations of the target object. In this study, we tested whether such online grip adjustments are automatic responses or can be controlled volitionally. Subjects performed virtual grasping movements toward target 2D shapes that sometimes changed shape or orientation during movement. Unlike in previous studies, the conditions and task requirements discouraged any online adjustments toward the perturbed shapes. In Experiment 1, target shapes were perturbed briefly (200 ms) during movement before reverting to the original shape, and subjects were instructed to ignore the transient perturbations. Despite subjects' intentions, we observed online adjustments of grip orientation that were toward the expected grip axis of the briefly presented shape. In Experiment 2, we added a stop-signal to the grasping task, with target perturbation as the stop cue. We again observed unnecessary online adjustments toward the grip axis of the perturbed shape, with similar latency. Furthermore, the grip adjustments continued after the forward motion of the hand had stopped, indicating that the automatic response to the perturbed target shape co-occurred with the volitional response to the perturbation onset. Our results provide evidence that automatic control mechanisms are used to guide the fingers to appropriate grasp points and suggest that these mechanisms are distinct from those involved with volitional control. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Soft shape-adaptive gripping device made from artificial muscle

NASA Astrophysics Data System (ADS)

Hamburg, E.; Vunder, V.; Johanson, U.; Kaasik, F.; Aabloo, A.

2016-04-01

We report on a multifunctional four-finger gripper for soft robotics, suitable for performing delicate manipulation tasks. The gripping device is comprised of separately driven gripping and lifting mechanisms, both made from a separate single piece of smart material - ionic capacitive laminate (ICL) also known as artificial muscle. Compared to other similar devices the relatively high force output of the ICL material allows one to construct a device able to grab and lift objects exceeding multiple times its own weight. Due to flexible design of ICL grips, the device is able to adapt the complex shapes of different objects and allows grasping single or multiple objects simultaneously without damage. The performance of the gripper is evaluated in two different configurations: a) the ultimate grasping strength of the gripping hand; and b) the maximum lifting force of the lifting actuator. The ICL is composed of three main layers: a porous membrane consisting of non-ionic polymer poly(vinylidene fluoride-co-hexafluoropropene) (PVdF-HFP), ionic liquid 1-ethyl-3-methylimidazolium trifluoromethane-sulfonate (EMITFS), and a reinforcing layer of woven fiberglass cloth. Both sides of the membrane are coated with a carbonaceous electrode. The electrodes are additionally covered with thin gold layers, serving as current collectors. Device made of this material operates silently, requires low driving voltage (<3 V), and is suitable for performing tasks in open air environment.

Influence of central set on anticipatory and triggered grip-force adjustments

NASA Technical Reports Server (NTRS)

Winstein, C. J.; Horak, F. B.; Fisher, B. E.; Peterson, B. W. (Principal Investigator)

2000-01-01

The effects of predictability of load magnitude on anticipatory and triggered grip-force adjustments were studied as nine normal subjects used a precision grip to lift, hold, and replace an instrumented test object. Experience with a predictable stimulus has been shown to enhance magnitude scaling of triggered postural responses to different amplitudes of perturbations. However, this phenomenon, known as a central-set effect, has not been tested systematically for grip-force responses in the hand. In our study, predictability was manipulated by applying load perturbations of different magnitudes to the test object under conditions in which the upcoming load magnitude was presented repeatedly or under conditions in which the load magnitudes were presented randomly, each with two different pre-load grip conditions (unconstrained and constrained). In constrained conditions, initial grip forces were maintained near the minimum level necessary to prevent pre-loaded object slippage, while in unconstrained conditions, no initial grip force restrictions were imposed. The effect of predictable (blocked) and unpredictable (random) load presentations on scaling of anticipatory and triggered grip responses was tested by comparing the slopes of linear regressions between the imposed load and grip response magnitude. Anticipatory and triggered grip force responses were scaled to load magnitude in all conditions. However, regardless of pre-load grip force constraint, the gains (slopes) of grip responses relative to load magnitudes were greater when the magnitude of the upcoming load was predictable than when the load increase was unpredictable. In addition, a central-set effect was evidenced by the fewer number of drop trials in the predictable relative to unpredictable load conditions. Pre-load grip forces showed the greatest set effects. However, grip responses showed larger set effects, based on prediction, when pre-load grip force was constrained to lower levels. These results suggest that anticipatory processes pertaining to load magnitude permit the response gain of both voluntary and triggered rapid grip force adjustments to be set, at least partially, prior to perturbation onset. Comparison of anticipatory set effects for reactive torque and lower extremity EMG postural responses triggered by surface translation perturbations suggests a more general rule governing anticipatory processes.

Independent digit movements and precision grip patterns in 1-5-month-old human infants: hand-babbling, including vacuous then self-directed hand and digit movements, precedes targeted reaching.

PubMed

Wallace, Patricia S; Whishaw, Ian Q

2003-01-01

Previous work has described human reflexive grasp patterns in early infancy and visually guided reaching and grasping in late infancy. There has been no examination of hand movements in the intervening period. This was the purpose of the present study. We video recorded the spontaneous hand and digit movements made by alert infants over their first 5 months of age. Over this period, spontaneous hand and digit movements developed from fists to almost continuous, vacuous movements and then to self-directed grasping movements. Amongst the many hand and digit movements observed, four grasping patterns emerged during this period: fists, pre-precision grips associated with numerous digit postures, precision grips including the pincer grasp, and self-directed grasps. The finding that a wide range of independent digit movements and grasp patterns are displayed spontaneously by infants within their first 5 months of age is discussed in relation to the development of the motor system, including the suggestion that direct connections of the pyramidal tract are functional relatively early in infancy. It is also suggested that hand babbling, consisting of first vacuous and then self-directed movements, is preparatory to targeted reaching.

Anatomical variations of the deep head of Cruveilhier of the flexor pollicis brevis and its significance for the evolution of the precision grip.

PubMed

Dunlap, Samuel S; Aziz, M Ashraf; Ziermann, Janine M

2017-01-01

Cruveilhier described in 1834 the human flexor pollicis brevis (FPB), a muscle of the thenar compartment, as having a superficial and a deep head, respectively, inserted onto the radial and ulnar sesamoids of the thumb. Since then, Cruveilhier's deep head has been controversially discussed. Often this deep head is confused with Henle's "interosseous palmaris volaris" or said to be a slip of the oblique adductor pollicis. In the 1960s, Day and Napier described anatomical variations of the insertions of Cruveilhier's deep head, including its absence, and hypothesized, that the shift of the deep head's insertion from ulnar to radial facilitated "true opposability" in anthropoids. Their general thesis for muscular arrangements underlying the power and precision grip is sound, but they did not delineate their deep head from Henle's muscle or the adductor pollicis, and their description of the attachments of Cruveilhier's deep head were too vague and not supported by a significant portion of the anatomical literature. Here, we reinvestigated Cruveilhier's deep head to resolve the controversy about it and because many newer anatomy textbooks do not describe this muscle, while it is often an obvious functionally (writing, texting, precision grip) and clinically significant thenar muscle. For the first time, we empirically delineated Cruveilhier's deep head from neighboring muscles with which it was previously confused. We observed 100% occurrence of the uncontested deep head in 80 human hands, displaying a similar variability of insertions as Day and Napier, but in significantly different numbers. Furthermore, we found variability in the origin and included as important landmarks the trapezoid and the ligamentum carpi radiatum. We tested the assertion regarding the evolutionary morphology and its role in the improvements in thumb movements during various precision grips. Our overall conclusions differ with respect to the developmental and evolutionary origin of the FPB heads.

Anatomical variations of the deep head of Cruveilhier of the flexor pollicis brevis and its significance for the evolution of the precision grip

PubMed Central

Aziz, M. Ashraf

2017-01-01

Cruveilhier described in 1834 the human flexor pollicis brevis (FPB), a muscle of the thenar compartment, as having a superficial and a deep head, respectively, inserted onto the radial and ulnar sesamoids of the thumb. Since then, Cruveilhier’s deep head has been controversially discussed. Often this deep head is confused with Henle’s “interosseous palmaris volaris” or said to be a slip of the oblique adductor pollicis. In the 1960s, Day and Napier described anatomical variations of the insertions of Cruveilhier’s deep head, including its absence, and hypothesized, that the shift of the deep head’s insertion from ulnar to radial facilitated “true opposability” in anthropoids. Their general thesis for muscular arrangements underlying the power and precision grip is sound, but they did not delineate their deep head from Henle’s muscle or the adductor pollicis, and their description of the attachments of Cruveilhier’s deep head were too vague and not supported by a significant portion of the anatomical literature. Here, we reinvestigated Cruveilhier’s deep head to resolve the controversy about it and because many newer anatomy textbooks do not describe this muscle, while it is often an obvious functionally (writing, texting, precision grip) and clinically significant thenar muscle. For the first time, we empirically delineated Cruveilhier’s deep head from neighboring muscles with which it was previously confused. We observed 100% occurrence of the uncontested deep head in 80 human hands, displaying a similar variability of insertions as Day and Napier, but in significantly different numbers. Furthermore, we found variability in the origin and included as important landmarks the trapezoid and the ligamentum carpi radiatum. We tested the assertion regarding the evolutionary morphology and its role in the improvements in thumb movements during various precision grips. Our overall conclusions differ with respect to the developmental and evolutionary origin of the FPB heads. PMID:29121048

Deficits in inhibitory force control in young adults with ADHD.

PubMed

Neely, Kristina A; Wang, Peiyuan; Chennavasin, Amanda P; Samimy, Shaadee; Tucker, Jacqueline; Merida, Andrea; Perez-Edgar, Koraly; Huang-Pollock, Cynthia

2017-05-01

Poor inhibitory control is a well-established cognitive correlate of adults with ADHD. However, the simple reaction time (RT) task used in a majority of studies records performance errors only via the presence or absence of a single key press. This all-or-nothing response makes it impossible to capture subtle differences in underlying processes that shape performance. Subsequently, all-or-nothing tasks may underestimate the prevalence of executive function deficits in ADHD. The current study measured inhibitory control using a standard Go/No-Go RT task and a more sensitive continuous grip force task among adults with (N=51, 22 female) and without (N=51, 29 female) ADHD. Compared to adults without ADHD, adults with ADHD made more failed inhibits in the classic Go/No-Go paradigm and produced greater and more variable force during motor inhibition. The amount of force produced on failed inhibits was a stronger predictor of ADHD-related symptoms than the number of commissions in the standard RT task. Adults with ADHD did not differ from those without ADHD on the mean force and variability of force produced in Go trials. These findings suggest that the use of a precise and continuous motor task, such as the force task used here, provides additional information about the nature of inhibitory motor control in adults with ADHD. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of glovebox gloves on grip and key pinch strength and contact forces for simulated manual operations with three commonly used hand tools.

PubMed

Sung, Peng-Cheng

2014-01-01

This study examined the effects of glovebox gloves for 11 females on maximum grip and key pinch strength and on contact forces generated from simulated tasks of a roller, a pair of tweezers and a crescent wrench. The independent variables were gloves fabricated of butyl, CSM/hypalon and neoprene materials; two glove thicknesses; and layers of gloves worn including single, double and triple gloving. CSM/hypalon and butyl gloves produced greater grip strength than the neoprene gloves. CSM/hypalon gloves also lowered contact forces for roller and wrench tasks. Single gloving and thin gloves improved hand strength performances. However, triple layers lowered contact forces for all tasks. Based on the evaluating results, selection and design recommendations of gloves for three hand tools were provided to minimise the effects on hand strength and optimise protection of the palmar hand in glovebox environments. To improve safety and health in the glovebox environments where gloves usage is a necessity, this study provides recommendations for selection and design of glovebox gloves for three hand tools including a roller, a pair of tweezers and a crescent wrench based on the results discovered in the experiments.

Real-time vision, tactile cues, and visual form agnosia: removing haptic feedback from a “natural” grasping task induces pantomime-like grasps

PubMed Central

Whitwell, Robert L.; Ganel, Tzvi; Byrne, Caitlin M.; Goodale, Melvyn A.

2015-01-01

Investigators study the kinematics of grasping movements (prehension) under a variety of conditions to probe visuomotor function in normal and brain-damaged individuals. “Natural” prehensile acts are directed at the goal object and are executed using real-time vision. Typically, they also entail the use of tactile, proprioceptive, and kinesthetic sources of haptic feedback about the object (“haptics-based object information”) once contact with the object has been made. Natural and simulated (pantomimed) forms of prehension are thought to recruit different cortical structures: patient DF, who has visual form agnosia following bilateral damage to her temporal-occipital cortex, loses her ability to scale her grasp aperture to the size of targets (“grip scaling”) when her prehensile movements are based on a memory of a target previewed 2 s before the cue to respond or when her grasps are directed towards a visible virtual target but she is denied haptics-based information about the target. In the first of two experiments, we show that when DF performs real-time pantomimed grasps towards a 7.5 cm displaced imagined copy of a visible object such that her fingers make contact with the surface of the table, her grip scaling is in fact quite normal. This finding suggests that real-time vision and terminal tactile feedback are sufficient to preserve DF’s grip scaling slopes. In the second experiment, we examined an “unnatural” grasping task variant in which a tangible target (along with any proxy such as the surface of the table) is denied (i.e., no terminal tactile feedback). To do this, we used a mirror-apparatus to present virtual targets with and without a spatially coincident copy for the participants to grasp. We compared the grasp kinematics from trials with and without terminal tactile feedback to a real-time-pantomimed grasping task (one without tactile feedback) in which participants visualized a copy of the visible target as instructed in our laboratory in the past. Compared to natural grasps, removing tactile feedback increased RT, slowed the velocity of the reach, reduced in-flight grip aperture, increased the slopes relating grip aperture to target width, and reduced the final grip aperture (FGA). All of these effects were also observed in the real time-pantomime grasping task. These effects seem to be independent of those that arise from using the mirror in general as we also compared grasps directed towards virtual targets to those directed at real ones viewed directly through a pane of glass. These comparisons showed that the grasps directed at virtual targets increased grip aperture, slowed the velocity of the reach, and reduced the slopes relating grip aperture to the widths of the target. Thus, using the mirror has real consequences on grasp kinematics, reflecting the importance of task-relevant sources of online visual information for the programming and updating of natural prehensile movements. Taken together, these results provide compelling support for the view that removing terminal tactile feedback, even when the grasps are target-directed, induces a switch from real-time visual control towards one that depends more on visual perception and cognitive supervision. Providing terminal tactile feedback and real-time visual information can evidently keep the dorsal visuomotor system operating normally for prehensile acts. PMID:25999834

Real-time vision, tactile cues, and visual form agnosia: removing haptic feedback from a "natural" grasping task induces pantomime-like grasps.

PubMed

Whitwell, Robert L; Ganel, Tzvi; Byrne, Caitlin M; Goodale, Melvyn A

2015-01-01

Investigators study the kinematics of grasping movements (prehension) under a variety of conditions to probe visuomotor function in normal and brain-damaged individuals. "Natural" prehensile acts are directed at the goal object and are executed using real-time vision. Typically, they also entail the use of tactile, proprioceptive, and kinesthetic sources of haptic feedback about the object ("haptics-based object information") once contact with the object has been made. Natural and simulated (pantomimed) forms of prehension are thought to recruit different cortical structures: patient DF, who has visual form agnosia following bilateral damage to her temporal-occipital cortex, loses her ability to scale her grasp aperture to the size of targets ("grip scaling") when her prehensile movements are based on a memory of a target previewed 2 s before the cue to respond or when her grasps are directed towards a visible virtual target but she is denied haptics-based information about the target. In the first of two experiments, we show that when DF performs real-time pantomimed grasps towards a 7.5 cm displaced imagined copy of a visible object such that her fingers make contact with the surface of the table, her grip scaling is in fact quite normal. This finding suggests that real-time vision and terminal tactile feedback are sufficient to preserve DF's grip scaling slopes. In the second experiment, we examined an "unnatural" grasping task variant in which a tangible target (along with any proxy such as the surface of the table) is denied (i.e., no terminal tactile feedback). To do this, we used a mirror-apparatus to present virtual targets with and without a spatially coincident copy for the participants to grasp. We compared the grasp kinematics from trials with and without terminal tactile feedback to a real-time-pantomimed grasping task (one without tactile feedback) in which participants visualized a copy of the visible target as instructed in our laboratory in the past. Compared to natural grasps, removing tactile feedback increased RT, slowed the velocity of the reach, reduced in-flight grip aperture, increased the slopes relating grip aperture to target width, and reduced the final grip aperture (FGA). All of these effects were also observed in the real time-pantomime grasping task. These effects seem to be independent of those that arise from using the mirror in general as we also compared grasps directed towards virtual targets to those directed at real ones viewed directly through a pane of glass. These comparisons showed that the grasps directed at virtual targets increased grip aperture, slowed the velocity of the reach, and reduced the slopes relating grip aperture to the widths of the target. Thus, using the mirror has real consequences on grasp kinematics, reflecting the importance of task-relevant sources of online visual information for the programming and updating of natural prehensile movements. Taken together, these results provide compelling support for the view that removing terminal tactile feedback, even when the grasps are target-directed, induces a switch from real-time visual control towards one that depends more on visual perception and cognitive supervision. Providing terminal tactile feedback and real-time visual information can evidently keep the dorsal visuomotor system operating normally for prehensile acts.

Handedness for Unimanual Grasping in 564 Great Apes: The Effect on Grip Morphology and a Comparison with Hand Use for a Bimanual Coordinated Task

PubMed Central

Meguerditchian, Adrien; Phillips, Kimberley A.; Chapelain, Amandine; Mahovetz, Lindsay M.; Milne, Scott; Stoinski, Tara; Bania, Amanda; Lonsdorf, Elizabeth; Schaeffer, Jennifer; Russell, Jamie; Hopkins, William D.

2015-01-01

A number of factors have been proposed to influence within and between species variation in handedness in non-human primates. In the initial study, we assessed the influence of grip morphology on hand use for simple reaching in a sample of 564 great apes including 49 orangutans Pongo pygmaeus, 66 gorillas Gorilla gorilla, 354 chimpanzees Pan troglodytes and 95 bonobos Pan paniscus. Overall, we found a significant right hand bias for reaching. We also found a significant effect of the grip morphology of hand use. Grasping with the thumb and index finger was more prevalent in the right compared to left hand in all four species. There was no significant sex effect on the patterns of handedness. In a subsample of apes, we also compared consistency in hand use for simple reaching with previously published data on a task that measures handedness for bimanual actions. We found that the ratio of subjects with consistent right compared to left hand use was more prevalent in bonobos, chimpanzees and gorillas but not orangutans. However, for all species, the proportion of subjects with inconsistent hand preferences between the tasks was relatively high suggesting some measures may be more sensitive in assessing handedness than others. PMID:26635693

Handedness for Unimanual Grasping in 564 Great Apes: The Effect on Grip Morphology and a Comparison with Hand Use for a Bimanual Coordinated Task.

PubMed

Meguerditchian, Adrien; Phillips, Kimberley A; Chapelain, Amandine; Mahovetz, Lindsay M; Milne, Scott; Stoinski, Tara; Bania, Amanda; Lonsdorf, Elizabeth; Schaeffer, Jennifer; Russell, Jamie; Hopkins, William D

2015-01-01

A number of factors have been proposed to influence within and between species variation in handedness in non-human primates. In the initial study, we assessed the influence of grip morphology on hand use for simple reaching in a sample of 564 great apes including 49 orangutans Pongo pygmaeus, 66 gorillas Gorilla gorilla, 354 chimpanzees Pan troglodytes and 95 bonobos Pan paniscus. Overall, we found a significant right hand bias for reaching. We also found a significant effect of the grip morphology of hand use. Grasping with the thumb and index finger was more prevalent in the right compared to left hand in all four species. There was no significant sex effect on the patterns of handedness. In a subsample of apes, we also compared consistency in hand use for simple reaching with previously published data on a task that measures handedness for bimanual actions. We found that the ratio of subjects with consistent right compared to left hand use was more prevalent in bonobos, chimpanzees and gorillas but not orangutans. However, for all species, the proportion of subjects with inconsistent hand preferences between the tasks was relatively high suggesting some measures may be more sensitive in assessing handedness than others.

Muscular forearm activation in hand-grip tasks with superimposition of mechanical vibrations.

PubMed

Fattorini, L; Tirabasso, A; Lunghi, A; Di Giovanni, R; Sacco, F; Marchetti, E

2016-02-01

The purpose of this paper is to evaluate the muscular activation of the forearm, with or without vibration stimuli at different frequencies while performing a grip tasks of 45s at various level of exerted force. In 16 individuals, 9 females and 7 males, the surface electromyogram (EMG) of extensor carpi radialis longus and the flexor carpi ulnari muscles were assessed. At a short latency from onset EMG, RMS and the level of MU synchronization were assessed to evaluate the muscular adaptations. Whilst a trend of decay of EMG Median frequency (MDFd) was employed as an index of muscular fatigue. Muscular tasks consists of the grip of an instrumented handle at a force level of 20%, 30%, 40%, 60% of the maximum voluntary force. Vibration was supplied by a shaker to the hand in mono-frequential waves at 20, 30, 33 and 40Hz. In relation to EMG, RMS and MU synchronization, the muscular activation does not seem to change with the superimposition of the mechanical vibrations, on the contrary a lower MDFd was observed at 33Hz than in absence of vibration. This suggests an early muscular fatigue induced by vibration due to the fact that 33Hz is a resonance frequency for the hand-arm system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Video stimuli reduce object-directed imitation accuracy: a novel two-person motion-tracking approach.

PubMed

Reader, Arran T; Holmes, Nicholas P

2015-01-01

Imitation is an important form of social behavior, and research has aimed to discover and explain the neural and kinematic aspects of imitation. However, much of this research has featured single participants imitating in response to pre-recorded video stimuli. This is in spite of findings that show reduced neural activation to video vs. real life movement stimuli, particularly in the motor cortex. We investigated the degree to which video stimuli may affect the imitation process using a novel motion tracking paradigm with high spatial and temporal resolution. We recorded 14 positions on the hands, arms, and heads of two individuals in an imitation experiment. One individual freely moved within given parameters (moving balls across a series of pegs) and a second participant imitated. This task was performed with either simple (one ball) or complex (three balls) movement difficulty, and either face-to-face or via a live video projection. After an exploratory analysis, three dependent variables were chosen for examination: 3D grip position, joint angles in the arm, and grip aperture. A cross-correlation and multivariate analysis revealed that object-directed imitation task accuracy (as represented by grip position) was reduced in video compared to face-to-face feedback, and in complex compared to simple difficulty. This was most prevalent in the left-right and forward-back motions, relevant to the imitator sitting face-to-face with the actor or with a live projected video of the same actor. The results suggest that for tasks which require object-directed imitation, video stimuli may not be an ecologically valid way to present task materials. However, no similar effects were found in the joint angle and grip aperture variables, suggesting that there are limits to the influence of video stimuli on imitation. The implications of these results are discussed with regards to previous findings, and with suggestions for future experimentation.

Impaired force control in writer's cramp showing a bilateral deficit in sensorimotor integration.

PubMed

Bleton, Jean-Pierre; Teremetz, Maxime; Vidailhet, Marie; Mesure, Serge; Maier, Marc A; Lindberg, Påvel G

2014-01-01

Abnormal cortical processing of sensory inputs has been found bilaterally in writer's cramp (WC). This study tested the hypothesis that patients with WC have an impaired ability to adjust grip forces according to visual and somatosensory cues in both hands. A unimanual visuomotor force-tracking task and a bimanual sense of effort force-matching task were performed by WC patients and healthy controls. In visuomotor tracking, WC patients showed increased error, greater variability, and longer release duration than controls. In the force-matching task, patients underestimated, whereas controls overestimated, the force applied in the other hand. Visuomotor tracking and force matching were equally impaired in both the symptomatic and nonsymptomatic hand in WC patients. This study provides evidence of bilaterally impaired grip-force control in WC, when using visual or sense of effort cues. This suggests a generalized subclinical deficit in sensorimotor integration in WC. Copyright © 2013 Movement Disorder Society.

Comparing two methods to record maximal voluntary contractions and different electrode positions in recordings of forearm extensor muscle activity: Refining risk assessments for work-related wrist disorders.

PubMed

Dahlqvist, Camilla; Nordander, Catarina; Granqvist, Lothy; Forsman, Mikael; Hansson, Gert-Åke

2018-01-01

Wrist disorders are common in force demanding industrial repetitive work. Visual assessment of force demands have a low reliability, instead surface electromyography (EMG) may be used as part of a risk assessment for work-related wrist disorders. For normalization of EMG recordings, a power grip (hand grip) is often used as maximal voluntary contraction (MVC) of the forearm extensor muscles. However, the test-retest reproducibility is poor and EMG amplitudes exceeding 100% have occasionally been recorded during work. An alternative MVC is resisted wrist extension, which may be more reliable. To compare hand grip and resisted wrist extension MVCs, in terms of amplitude and reproducibility, and to examine the effect of electrode positioning. Twelve subjects participated. EMG from right forearm extensors, from four electrode pairs, was recorded during MVCs, on three separate occasions. The group mean EMG amplitudes for resisted wrist extension were 1.2-1.7 times greater than those for hand grip. Resisted wrist extension showed better reproducibility than hand grip. The results indicate that the use of resisted wrist extension is a more accurate measurement of maximal effort of wrist extensor contractions than using hand grip and should increase the precision in EMG recordings from forearm extensor muscles, which in turn will increase the quality of risk assessments that are based on these.

Altered behavior in experimental cortical dysplasia.

PubMed

Zhou, Fu-Wen; Rani, Asha; Martinez-Diaz, Hildabelis; Foster, Thomas C; Roper, Steven N

2011-12-01

Developmental delay and cognitive impairment are common comorbidities in people with epilepsy associated with malformations of cortical development (MCDs). We studied cognition and behavior in an animal model of diffuse cortical dysplasia (CD), in utero irradiation, using a battery of behavioral tests for neuromuscular and cognitive function. Fetal rats were exposed to 2.25 Gy external radiation on embryonic day 17 (E17). At 1 month of age they were tested using an open field task, a grip strength task, a grid walk task, inhibitory avoidance, an object recognition task, and the Morris water maze task. Rats with CD showed reduced nonlocomotor activity in the open field task and impaired motor coordination for grid walking but normal grip strength. They showed a reduced tendency to recognize novel objects and reduced retention in an inhibitory avoidance task. Water maze testing showed that learning and memory were impaired in irradiated rats for both cue discrimination and spatially oriented tasks. These results demonstrate significant deficits in cortex- and hippocampus-dependent cognitive functions associated with the diffuse abnormalities of cortical and hippocampal development that have been documented in this model. This study documents multimodal cognitive deficits associated with CD and can serve as the foundation for future investigations into the mechanisms of and possible therapeutic interventions for this problem. Wiley Periodicals, Inc. © 2011 International League Against Epilepsy.

Grip Force Adjustments Reflect Prediction of Dynamic Consequences in Varying Gravitoinertial Fields

PubMed Central

White, Olivier; Thonnard, Jean-Louis; Lefèvre, Philippe; Hermsdörfer, Joachim

2018-01-01

Humans have a remarkable ability to adjust the way they manipulate tools through a genuine regulation of grip force according to the task. However, rapid changes in the dynamical context may challenge this skill, as shown in many experimental approaches. Most experiments adopt perturbation paradigms that affect only one sensory modality. We hypothesize that very fast adaptation can occur if coherent information from multiple sensory modalities is provided to the central nervous system. Here, we test whether participants can switch between different and never experienced dynamical environments induced by centrifugation of the body. Seven participants lifted an object four times in a row successively in 1, 1.5, 2, 2.5, 2, 1.5, and 1 g. We continuously measured grip force, load force and the gravitoinertial acceleration that was aligned with body axis (perceived gravity). Participants adopted stereotyped grasping movements immediately upon entry in a new environment and needed only one trial to adapt grip forces to a stable performance in each new gravity environment. This result was underlined by good correlations between grip and load forces in the first trial. Participants predictively applied larger grip forces when they expected increasing gravity steps. They also decreased grip force when they expected decreasing gravity steps, but not as much as they could, indicating imperfect anticipation in that condition. The participants' performance could rather be explained by a combination of successful scaling of grip force according to gravity changes and a separate safety factor. The data suggest that in highly unfamiliar dynamic environments, grip force regulation is characterized by a combination of a successful anticipation of the experienced environmental condition, a safety factor reflecting strategic response to uncertainties about the environment and rapid feedback mechanisms to optimize performance under constant conditions. PMID:29527176

Inertial torque during reaching directly impacts grip-force adaptation to weightless objects.

PubMed

Giard, T; Crevecoeur, F; McIntyre, J; Thonnard, J-L; Lefèvre, P

2015-11-01

A hallmark of movement control expressed by healthy humans is the ability to gradually improve motor performance through learning. In the context of object manipulation, previous work has shown that the presence of a torque load has a direct impact on grip-force control, characterized by a significantly slower grip-force adjustment across lifting movements. The origin of this slower adaptation rate remains unclear. On the one hand, information about tangential constraints during stationary holding may be difficult to extract in the presence of a torque. On the other hand, inertial torque experienced during movement may also potentially disrupt the grip-force adjustments, as the dynamical constraints clearly differ from the situation when no torque load is present. To address the influence of inertial torque loads, we instructed healthy adults to perform visually guided reaching movements in weightlessness while holding an unbalanced object relative to the grip axis. Weightlessness offered the possibility to remove gravitational constraints and isolate the effect of movement-related feedback on grip force adjustments. Grip-force adaptation rates were compared with a control group who manipulated a balanced object without any torque load and also in weightlessness. Our results clearly show that grip-force adaptation in the presence of a torque load is significantly slower, which suggests that the presence of torque loads experienced during movement may alter our internal estimates of how much force is required to hold an unbalanced object stable. This observation may explain why grasping objects around the expected location of the center of mass is such an important component of planning and control of manipulation tasks.

Electrogoniometer measurement and directional analysis of wrist angles and movements during the Sollerman hand function test.

PubMed

Dauncey, Thomas; Singh, Harvinder P; Dias, Joseph J

Clinical measurement. To investigate the characteristics of wrist motion (area, axis, and location) during activities of daily living (ADL) using electrogoniometry. A sample of 83 normal volunteers performed the Sollerman hand function test (SHFT) with a flexible biaxial electrogoniometer applied to their wrists. This technique is accurate and reliable and has been used before for assessment of wrist circumduction in normal volunteers. A software package was used to overlay an ellipse of best fit around the 2-dimensional trace of the electrogoniometer mathematically computing the area, location, and axis angle of the ellipse. Most ADL could be completed within 20% of the total area of circumduction (3686°° ± 1575°°) of a normal wrist. An oblique plane in radial extension and ulnar flexion (dart-throwing motion plane) was used for rotation (-14° ± 32°) and power grip tasks (-29° ± 25°) during ADL; however, precision tasks (4° ± 28°), like writing, were performed more often in the flexion extension plane. In the dominant hand, only 2 power tasks were located in flexion region (cutting play dough [ulnar] and pouring carton [radial]), precision tasks were located centrally, and rotation and other power tasks were located in extension region. This study has identified that wrist motion during the ADL requires varying degrees of movement in oblique planes. Using electrogoniometry, we could visualize the area, location, and plane of motion during ADL. This could assist future researchers to compare procedures leading to loss of motion in specific quadrants of wrist motion and its impact on patient's ability in performing particular ADL. It could guide hand therapists to specifically focus on retraining the ADL that may be affected when wrist range of motion is lost after injury. Diagnostic level III. Copyright © 2016 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Taxonomy based analysis of force exchanges during object grasping and manipulation

PubMed Central

Martin-Brevet, Sandra; Jarrassé, Nathanaël; Burdet, Etienne

2017-01-01

The flexibility of the human hand in object manipulation is essential for daily life activities, but remains relatively little explored with quantitative methods. On the one hand, recent taxonomies describe qualitatively the classes of hand postures for object grasping and manipulation. On the other hand, the quantitative analysis of hand function has been generally restricted to precision grip (with thumb and index opposition) during lifting tasks. The aim of the present study is to fill the gap between these two kinds of descriptions, by investigating quantitatively the forces exerted by the hand on an instrumented object in a set of representative manipulation tasks. The object was a parallelepiped object able to measure the force exerted on the six faces and its acceleration. The grasping force was estimated from the lateral force and the unloading force from the bottom force. The protocol included eleven tasks with complementary constraints inspired by recent taxonomies: four tasks corresponding to lifting and holding the object with different grasp configurations, and seven to manipulating the object (rotation around each of its axis and translation). The grasping and unloading forces and object rotations were measured during the five phases of the actions: unloading, lifting, holding or manipulation, preparation to deposit, and deposit. The results confirm the tight regulation between grasping and unloading forces during lifting, and extend this to the deposit phase. In addition, they provide a precise description of the regulation of force exchanges during various manipulation tasks spanning representative actions of daily life. The timing of manipulation showed both sequential and overlapping organization of the different sub-actions, and micro-errors could be detected. This phenomenological study confirms the feasibility of using an instrumented object to investigate complex manipulative behavior in humans. This protocol will be used in the future to investigate upper-limb dexterity in patients with sensory-motor impairments. PMID:28562617

Functional studies in 79-year-olds. II. Upper extremity function.

PubMed

Lundgren-Lindquist, B; Sperling, L

1983-01-01

As part of the Gerontological and Geriatric Population Study of 79-year-old people in Göteborg, a representative subsample comprising 112 women and 93 men took part in a study of upper extremity function. Thirty-eight per cent of the women and 37% of the men had disorders in the upper extremities. The investigation included tests of co-ordination, static strength in the key-grip and the transversal volar grip, power capacity in opening jars and a bottle, basal movements in the upper extremities in personal hygiene and dressing activities, function in the kitchen e.g. reaching shelves, manual tasks including tests of pronation and supination of the forearm. In the key-grip as well as in the transversal volar grip men showed a generally larger decrease in strength with age than women compared to 70-year-olds in a previous population study. Significant correlations were found between strength in the key-grip and the performance time in the test of co-ordination. Women produced about 66% of the muscular force of the men when opening jars. Significant correlations were found between strength in the transversal volar grip and the maximal torque for opening the jars. Female and male subjects who were not capable of handling the electric plug in the manual ability test had significantly weaker strength in the key-grip. The importance of designing products and adapting the environment so as to correspond to the functional capacity of the elderly, is emphasized.

Hand preferences in two unimanual and two bimanual coordinated tasks in the black-handed spider monkey (Ateles geoffroyi).

PubMed

Motes Rodrigo, Alba; Ramirez Torres, Carlos Eduardo; Hernandez Salazar, Laura Teresa; Laska, Matthias

2018-05-01

Spider monkeys are interesting to study with regard to hand preferences, as they are one of the few primate species that lack a thumb and, thus, are unable to perform a precision grip. Further, being platyrrhine primates, they also largely lack independent motor control of the digits and, thus, have only limited manual dexterity. It was therefore the aim of the present study to assess hand preferences in black-handed spider monkeys ( Ateles geoffroyi ) in 4 tasks differing in task demand: simple unimanual reaching for food and 3 versions of the widely used tube task, including 2 bimanual versions that differ from each other in the degree of fine motor control needed and a unimanual version that does not require coordinated action of the hands. We found that black-handed spider monkeys display significant hand preferences at the individual, but not at the population, level. This was true both in the 2 bimanual coordinated tasks and in the 2 unimanual tasks. Further, our results show that the majority of animals were consistent in the hand they preferred in these 4 tasks. Our findings only partially support the notion that task demand positively correlates with strength of hand preference. Finally, we found that the index finger was the most frequently used digit in all 3 tube tasks, although the animals also used other digits and 2- and 3-finger combinations to extract food from a tube. We conclude that limited manual dexterity does not prevent spider monkeys from displaying strong and consistent hand preferences at the individual level. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Robot training of upper limb in multiple sclerosis: comparing protocols with or without manipulative task components.

PubMed

Carpinella, Ilaria; Cattaneo, Davide; Bertoni, Rita; Ferrarin, Maurizio

2012-05-01

In this pilot study, we compared two protocols for robot-based rehabilitation of upper limb in multiple sclerosis (MS): a protocol involving reaching tasks (RT) requiring arm transport only and a protocol requiring both objects' reaching and manipulation (RMT). Twenty-two MS subjects were assigned to RT or RMT group. Both protocols consisted of eight sessions. During RT training, subjects moved the handle of a planar robotic manipulandum toward circular targets displayed on a screen. RMT protocol required patients to reach and manipulate real objects, by moving the robotic arm equipped with a handle which left the hand free for distal tasks. In both trainings, the robot generated resistive and perturbing forces. Subjects were evaluated with clinical and instrumental tests. The results confirmed that MS patients maintained the ability to adapt to the robot-generated forces and that the rate of motor learning increased across sessions. Robot-therapy significantly reduced arm tremor and improved arm kinematics and functional ability. Compared to RT, RMT protocol induced a significantly larger improvement in movements involving grasp (improvement in Grasp ARAT sub-score: RMT 77.4%, RT 29.5%, p=0.035) but not precision grip. Future studies are needed to evaluate if longer trainings and the use of robotic handles would significantly improve also fine manipulation.

An ergonomic evaluation of manual Cleco plier designs: effects of rubber grip, spring recoil, and worksurface angle.

PubMed

You, Heecheon; Kumar, Anil; Young, Ronda; Veluswamy, Prabaharan; Malzahn, Don E

2005-09-01

The present study evaluated two design modifications (rubber grip and torsion spring) to the conventional manual Cleco pliers by electromyography (EMG), hand discomfort, and design satisfaction. This study also surveyed workers' satisfaction with selected design features of the pliers for ergonomic improvement. A two-way (plier design x worksurface angle) within-subject (nested within gender and hand size) design was employed. Eleven workers simulated the plier task in an adjustable workstation for different plier designs and worksurface angles (0 degrees , 60 degrees , and 90 degrees ). Lower EMG values were obtained for the pliers with rubber grip and at 60 degrees of worksurface angle. EMG values varied significantly between the participants, but showed low correlations (Spearman's rank correlation = -0.27 approximately -0.58) with their work experience with the pliers. The hand discomfort and design satisfaction evaluations identified that the grip span (max = 14.0 cm) and grip force requirement (peak = 220.5 N) of the current pliers need ergonomic modification. The present study shows the needs of both the ergonomic design of a hand tool and the training of a proper work method to control work-related musculoskeletal disorders at the workplace.

A Test of Motor (Not Executive) Planning in Developmental Coordination Disorder and Autism

ERIC Educational Resources Information Center

van Swieten, Lisa M.; van Bergen, Elsje; Williams, Justin H. G.; Wilson, Andrew D.; Plumb, Mandy S.; Kent, Samuel W.; Mon-Williams, Mark A.

2010-01-01

Grip selection tasks have been used to test "planning" in both autism and developmental coordination disorder (DCD). We differentiate between "motor" and "executive" planning and present a modified motor planning task. Participants grasped a cylinder in 1 of 2 orientations before turning it clockwise or anticlockwise.…

A tailored workplace exercise program for women at risk for neck and upper limb musculoskeletal disorders: a randomized controlled trial.

PubMed

Rasotto, Chiara; Bergamin, Marco; Sieverdes, John C; Gobbo, Stefano; Alberton, Cristine L; Neunhaeuserer, Daniel; Maso, Stefano; Zaccaria, Marco; Ermolao, Andrea

2015-02-01

The aim of this study was to evaluate a tailored physical activity protocol performed in a work environment with a group of female workers employed in manual precision tasks to reduce upper limb pain. Sixty female subjects were randomly assigned to an intervention group or a control group. The IG was administered of a 6-month, twice-a-week, tailored exercise program, whereas the CG received no intervention. The IG showed a reduction on shoulder pain accompanied by increases on the range of motion measures. In addition, reductions in upper limb pain and neck disability were detected with concomitant increases in grip strength. This study indicated positive effects of a tailored workplace exercise protocol in female workers exposed to moderate risk for work-related musculoskeletal disorders, showing clinically meaningful reductions of pain symptoms and disability on upper limb and neck regions.

Effects of load position and force direction on back muscle loading in one-wheeled wheelbarrow tasks.

PubMed

Chen, Su-Huang; Lee, Yung-Hui; Lin, Chiuhsiang Joe

2015-01-01

Various parameters related to pushing/pulling tasks have been examined yet the effects of changing the load position in one-wheeled wheelbarrow task has not been examined. To explore the effects of load position and force direction on muscle activity during wheelbarrow tasks. Nine participants were recruited to take part in the experiment. Each participant performed 18 trials consisting of 2 force directions (push and pull) and 9 load positions. The dependent variables were EMG of erector spinae and gripping force. ANOVA was used to identify significant differences between force direction and load position in EMG and gripping force data. Results showed that peak EMG was lowest for the left and right erector spinae when the load was positioned farther from the participant. Peak EMG of the bilateral erector spinae increased when the weight was near the participant and on the ipsilateral hand. Based on the EMG results, we suggest that loads be arranged in the anterior part of the bin in order to reduce muscle activity on the spine during the wheelbarrow task. This finding also provides some directions in the improvement and ergonomic redesign of the one-wheeled wheelbarrow.

Transient impact of prolonged versus repetitive stretch on hand motor control in chronic stroke.

PubMed

Triandafilou, Kristen M; Ochoa, Jose; Kang, Xuan; Fischer, Heidi C; Stoykov, Mary Ellen; Kamper, Derek G

2011-01-01

The purpose of this study was to investigate the influence of prolonged and repetitive passive range of motion (PROM) stretching of the fingers on hand function in stroke survivors. Fifteen chronic stroke survivors with moderate to severe hand impairment took part in the study. Participants underwent 3 experimental sessions consisting of 30 minutes of rest, prolonged, or repetitive stretching of the finger flexor muscles by a powered glove orthosis (X-Glove). Outcome measures, comprised of 3 selected tasks from the Graded Wolf Motor Function Test (GWMFT), grip strength, lateral pinch strength, and grip relaxation time, were recorded at the start and end of each session. Change in outcome score for each session was used for analysis. Data suggested a trend for improvement following stretching, especially for the repetitive PROM case. For one GWMFT task (lift washcloth), the effect of stretching condition on performance time approached a statistical significance (P = .015), with repetitive PROM stretching producing the greatest mean reduction. Similarly, repetitive stretching led to a 12% ± 16% increase in grip strength, although this change was not statistically different across groups (P = .356); and grip termination time was reduced, albeit non-significantly, by 66% ± 133%. Repetitive PROM stretching exhibited trends to be more effective than prolonged stretching for improving hand motor control. Although the results were highly variable and the effects are undoubtedly transient, an extended period of repetitive PROM stretching may prove advantageous prior to hand therapy sessions to maximize treatment.

Motor control goes beyond physics: differential effects of gravity and inertia on finger forces during manipulation of hand-held objects.

PubMed

Zatsiorsky, Vladimir M; Gao, Fan; Latash, Mark L

2005-04-01

According to basic physics, the local effects induced by gravity and acceleration are identical and cannot be separated by any physical experiment. In contrast-as this study shows-people adjust the grip forces associated with gravitational and inertial forces differently. In the experiment, subjects oscillated a vertically-oriented handle loaded with five different weights (from 3.8 N to 13.8 N) at three different frequencies in the vertical plane: 1 Hz, 1.5 Hz and 2.0 Hz. Three contributions to the grip force-static, dynamic, and stato-dynamic fractions-were quantified. The static fraction reflects grip force related to holding a load statically. The stato-dynamic fraction reflects a steady change in the grip force when the same load is moved cyclically. The dynamic fraction is due to acceleration-related adjustments of the grip force during oscillation cycles. The slope of the relation between the grip force and the load force was steeper for the static fraction than for the dynamic fraction. The stato-dynamic fraction increased with the frequency and load. The slope of the dynamic grip force-load force relation decreased with frequency, and as a rule, increased with the load. Hence, when adjusting grip force to task requirements, the central controller takes into account not only the expected magnitude of the load force but also such factors as whether the force is gravitational or inertial and the contributions of the object mass and acceleration to the inertial force. As an auxiliary finding, a complex finger coordination pattern aimed at preserving the rotational equilibrium of the object during shaking movements was reported.

The bilateral movement condition facilitates maximal but not submaximal paretic-limb grip force in people with post-stroke hemiparesis

PubMed Central

DeJong, Stacey L.; Lang, Catherine E.

2012-01-01

Objectives Although healthy individuals have less force production capacity during bilateral muscle contractions compared to unilateral efforts, emerging evidence suggests that certain aspects of paretic upper limb task performance after stroke may be enhanced by moving bilaterally instead of unilaterally. We investigated whether the bilateral movement condition affects grip force differently on the paretic side of people with post-stroke hemiparesis, compared to their non-paretic side and both sides of healthy young adults. Methods Within a single session, we compared: 1) maximal grip force during unilateral vs. bilateral contractions on each side, and 2) force contributed by each side during a 30% submaximal bilateral contraction. Results Healthy controls produced less grip force in the bilateral condition, regardless of side (- 2.4% difference), and similar findings were observed on the non-paretic side of people with hemiparesis (- 4.5% difference). On the paretic side, however, maximal grip force was increased by the bilateral condition in most participants (+11.3% difference, on average). During submaximal bilateral contractions in each group, the two sides each contributed the same percentage of unilateral maximal force. Conclusions The bilateral condition facilitates paretic limb grip force at maximal, but not submaximal levels. Significance In some people with post-stroke hemiparesis, the paretic limb may benefit from bilateral training with high force requirements. PMID:22248812

Oxygenator Safety Evaluation: A Focus on Connection Grip Strength and Arterial Temperature Measurement Accuracy

PubMed Central

Newland, Richard F.; Baker, Robert A.; Sanderson, Andrew J.; Tuble, Sigrid C.; Tully, Phil J.

2012-01-01

Abstract: This report describes the assessment of three specific safety-related specifications in the consideration of an alternate oxygenator; first the grip strength relationship between various oxygenator connectors and SMARxT® tubing, second, the grip strength of various biopassive tubings and an isolated SMARxT® connector, and finally, the accuracy of the arterial outlet temperature measurement. Grip strength experiments for the connections between the SMARxT® tubing and the venous reservoir outlet and the oxygenator venous inlet and oxygenator arterial outlet of the Medtronic Affinity®, Sorin Synthesis®, Sorin Primox®, and Terumo Capiox® RX25 oxygenators were performed. In addition we compared the grip strength of polyvinyl chloride, Physio®, Trillium®, Carmeda®, X-Coating®, and SMARxT® tubing. The accuracy of the integrated arterial outlet temperature probes was determined by comparing the temperatures measured by the integrated probe with a precision reference thermometer. Connector grip strength comparisons for the evaluation oxygenators with SMARxT® tubing showed significant variation between oxygenators and connections (p = .02). Evaluation of the arterial outlet showed significant variation between evaluation oxygenators, while at the venous reservoir outlet and oxygenator inlet, there were no significant differences. Grip strength comparison data for the various tubing types demonstrated a main effect for tubing type F(5, 18) = 8.01, p = .002, ηp2 = .77. Temperature accuracy measurements demonstrated that all oxygenators overread the arterial outlet temperature at 15°C, whilst at temperatures ≥25°C, all oxygenators underread the arterial outlet temperature. The integrity of SMARxT® tubing connection is influenced by the connector type, and may decline over time, highlighting the importance to not consider interchanging components of the bypass circuit as inconsequential. PMID:22893983

Altered visual strategies and attention are related to increased force fluctuations during a pinch grip task in older adults.

PubMed

Keenan, Kevin G; Huddleston, Wendy E; Ernest, Bradley E

2017-11-01

The purpose of the study was to determine the visual strategies used by older adults during a pinch grip task and to assess the relations between visual strategy, deficits in attention, and increased force fluctuations in older adults. Eye movements of 23 older adults (>65 yr) were monitored during a low-force pinch grip task while subjects viewed three common visual feedback displays. Performance on the Grooved Pegboard test and an attention task (which required no concurrent hand movements) was also measured. Visual strategies varied across subjects and depended on the type of visual feedback provided to the subjects. First, while viewing a high-gain compensatory feedback display (horizontal bar moving up and down with force), 9 of 23 older subjects adopted a strategy of performing saccades during the task, which resulted in 2.5 times greater force fluctuations in those that exhibited saccades compared with those who maintained fixation near the target line. Second, during pursuit feedback displays (force trace moving left to right across screen and up and down with force), all subjects exhibited multiple saccades, and increased force fluctuations were associated ( r s = 0.6; P = 0.002) with fewer saccades during the pursuit task. Also, decreased low-frequency (<4 Hz) force fluctuations and Grooved Pegboard times were significantly related ( P = 0.033 and P = 0.005, respectively) with higher (i.e., better) attention z scores. Comparison of these results with our previously published results in young subjects indicates that saccadic eye movements and attention are related to force control in older adults. NEW & NOTEWORTHY The significant contributions of the study are the addition of eye movement data and an attention task to explain differences in hand motor control across different visual displays in older adults. Older participants used different visual strategies across varying feedback displays, and saccadic eye movements were related with motor performance. In addition, those older individuals with deficits in attention had impaired motor performance on two different hand motor control tasks, including the Grooved Pegboard test. Copyright © 2017 the American Physiological Society.

Control strategy for a dual-arm maneuverable space robot

NASA Technical Reports Server (NTRS)

Wang, P. K. C.

1987-01-01

A simple strategy for the attitude control and arm coordination of a maneuverable space robot with dual arms is proposed. The basic task for the robot consists of the placement of marked rigid solid objects with specified pairs of gripping points and a specified direction of approach for gripping. The strategy consists of three phases each of which involves only elementary rotational and translational collision-free maneuvers of the robot body. Control laws for these elementary maneuvers are derived by using a body-referenced dynamic model of the dual-arm robot.

Microscopic vision modeling method by direct mapping analysis for micro-gripping system with stereo light microscope.

PubMed

Wang, Yuezong; Zhao, Zhizhong; Wang, Junshuai

2016-04-01

We present a novel and high-precision microscopic vision modeling method, which can be used for 3D data reconstruction in micro-gripping system with stereo light microscope. This method consists of four parts: image distortion correction, disparity distortion correction, initial vision model and residual compensation model. First, the method of image distortion correction is proposed. Image data required by image distortion correction comes from stereo images of calibration sample. The geometric features of image distortions can be predicted though the shape deformation of lines constructed by grid points in stereo images. Linear and polynomial fitting methods are applied to correct image distortions. Second, shape deformation features of disparity distribution are discussed. The method of disparity distortion correction is proposed. Polynomial fitting method is applied to correct disparity distortion. Third, a microscopic vision model is derived, which consists of two models, i.e., initial vision model and residual compensation model. We derive initial vision model by the analysis of direct mapping relationship between object and image points. Residual compensation model is derived based on the residual analysis of initial vision model. The results show that with maximum reconstruction distance of 4.1mm in X direction, 2.9mm in Y direction and 2.25mm in Z direction, our model achieves a precision of 0.01mm in X and Y directions and 0.015mm in Z direction. Comparison of our model with traditional pinhole camera model shows that two kinds of models have a similar reconstruction precision of X coordinates. However, traditional pinhole camera model has a lower precision of Y and Z coordinates than our model. The method proposed in this paper is very helpful for the micro-gripping system based on SLM microscopic vision. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comprehension of handwriting development: Pen-grip kinetics in handwriting tasks and its relation to fine motor skills among school-age children.

PubMed

Lin, Yu-Chen; Chao, Yen-Li; Wu, Shyi-Kuen; Lin, Ho-Hsio; Hsu, Chieh-Hsiang; Hsu, Hsiao-Man; Kuo, Li-Chieh

2017-10-01

Numerous tools have been developed to evaluate handwriting performances by analysing written products. However, few studies have directly investigated kinetic performances of digits when holding a pen. This study thus attempts to investigate pen-grip kinetics during writing tasks of school-age children and explore the relationship between the kinetic factors and fine motor skills. This study recruited 181 children aged from 5 to 12 years old and investigated the effects of age on handwriting kinetics and the relationship between these and fine motor skills. The forces applied from the digits and pen-tip were measured during writing tasks via a force acquisition pen, and the children's fine motor performances were also evaluated. The results indicate that peak force and average force might not be direct indicators of handwriting performance for normally developing children at this age. Younger children showed larger force variation and lower adjustment frequency during writing, which might indicate they had poorer force control than the older children. Force control when handling a pen is significantly correlated with fine motor performance, especially in relation to the manual dexterity. A novel system is proposed for analysing school-age children's force control while handwriting. We observed the development of force control in relation to pen grip among the children with different ages in this study. The findings suggested that manipulation skill may be crucial when children are establishing their handwriting capabilities. © 2017 Occupational Therapy Australia.

Peripheral and central changes combine to induce motor behavioral deficits in a moderate repetition task

PubMed Central

Coq, Jacques-Olivier; Barr, Ann E; Strata, Fabrizio; Russier, Michael; Kietrys, David M; Merzenich, Michael M; Byl, Nancy N; Barbe, Mary F

2009-01-01

Repetitive motion disorders, such as carpal tunnel syndrome and focal hand dystonia, can be associated with tasks that require prolonged, repetitive behaviors. Previous studies using animal models of repetitive motion have correlated cortical neuroplastic changes or peripheral tissue inflammation with fine motor performance. However, the possibility that both peripheral and central mechanisms coexist with altered motor performance has not been studied. In this study, we investigated the relationship between motor behaviour changes associated with repetitive behaviors and both peripheral tissue inflammation and cortical neuroplasticity. A rat model of reaching and grasping involving moderate repetitive reaching with negligible force (MRNF) was used. Rats performed the MRNF task for 2 hrs/day, 3 days/wk for 8 weeks. Reach performance was monitored by measuring reach rate/success, daily exposure, reach movement reversals/patterns, reach/grasp phase times, grip strength and grooming function. With cumulative task exposure, reach performance, grip strength and agility declined while an inefficient food retrieval pattern increased. In S1 of MRNF rats, a dramatic disorganization of the topographic forepaw representation was observed, including the emergence of large receptive fields located on both the wrist/forearm and forepaw with alterations of neuronal properties. In M1, there was a drastic enlargement of the overall forepaw map area, and of the cortex devoted to digit, arm-digits and elbow-wrist responses. In addition, unusually low current amplitude evoked digit movements. IL-1β and TNF-α increased in forearm flexor muscles and tendons of MRNF animals. The increases in IL-1β and TNF-α negatively correlated with grip strength and amount of current needed to evoke forelimb movements. This study provides strong evidence that both peripheral inflammation and cortical neuroplasticity jointly contribute to the development of chronic repetitive motion disorders. PMID:19686738

Peripheral and central changes combine to induce motor behavioral deficits in a moderate repetition task.

PubMed

Coq, Jacques-Olivier; Barr, Ann E; Strata, Fabrizio; Russier, Michael; Kietrys, David M; Merzenich, Michael M; Byl, Nancy N; Barbe, Mary F

2009-12-01

Repetitive motion disorders, such as carpal tunnel syndrome and focal hand dystonia, can be associated with tasks that require prolonged, repetitive behaviors. Previous studies using animal models of repetitive motion have correlated cortical neuroplastic changes or peripheral tissue inflammation with fine motor performance. However, the possibility that both peripheral and central mechanisms coexist with altered motor performance has not been studied. In this study, we investigated the relationship between motor behavior changes associated with repetitive behaviors and both peripheral tissue inflammation and cortical neuroplasticity. A rat model of reaching and grasping involving moderate repetitive reaching with negligible force (MRNF) was used. Rats performed the MRNF task for 2 h/day, 3 days/week for 8 weeks. Reach performance was monitored by measuring reach rate/success, daily exposure, reach movement reversals/patterns, reach/grasp phase times, grip strength and grooming function. With cumulative task exposure, reach performance, grip strength and agility declined while an inefficient food retrieval pattern increased. In S1 of MRNF rats, a dramatic disorganization of the topographic forepaw representation was observed, including the emergence of large receptive fields located on both the wrist/forearm and forepaw with alterations of neuronal properties. In M1, there was a drastic enlargement of the overall forepaw map area, and of the cortex devoted to digit, arm-digits and elbow-wrist responses. In addition, unusually low current amplitude evoked digit movements. IL-1 beta and TNF-alpha increased in forearm flexor muscles and tendons of MRNF animals. The increases in IL-1 beta and TNF-alpha negatively correlated with grip strength and amount of current needed to evoke forelimb movements. This study provides strong evidence that both peripheral inflammation and cortical neuroplasticity jointly contribute to the development of chronic repetitive motion disorders.

The modulation of the motor resonance triggered by reach-to-grasp movements: No role of human physical similarity as conveyed by age.

PubMed

Marino, Barbara F M; Ricciardelli, Paola

2017-07-01

The activation of the mirror-neuron circuit during the observation of motor acts is thought to be the basis of human capacity to read the intentions behind the behavior of others. Growing empirical evidence shows a different activation of the mirror-neuron resonance mechanism depending on how much the observer and the observed agent share their motor repertoires. Here, the possible modulatory effect of physical similarity between the observer and the agent was investigated in three studies. We used a visuo-motor priming task in which participants were asked to categorize manipulable and non-manipulable objects into natural or man-made kinds after having watched precision and power reach-to-grasp movements. Physical similarity was manipulated by presenting reach-to-grasp movements performed by the hands of actors of three different age ranges that are adults of the same age as the participants, children, and elderly. Faster responses were observed in trials where power grip movements were performed by the adults and precision grip movements were performed by the elderly (Main Study). This finding is not in keeping with the idea that physical similarity shapes the mirror-neuron resonance. Instead, it suggests an effect of the kinematic organization of the reach-to-grasp movements, which systematically changed with the actor age as revealed by a kinematic analysis. The differential effect played by adult and elderly actor primes was lost when static grasping hands (Control Study 1) and reach-to-grasp movements with uniform kinematic profiles (Control Study 2) were used. Therefore, we found preliminary evidence that mirror-neuron resonance is not shaped by physical similarity but by the kinematics of the observed action. This finding is novel as it suggests that human ability to read the intentions behind the behavior of others may benefit from a mere visual processing of spatiotemporal patterns.

Grasp-specific motor resonance is influenced by the visibility of the observed actor.

PubMed

Bunday, Karen L; Lemon, Roger N; Kilner, James M; Davare, Marco; Orban, Guy A

2016-11-01

Motor resonance is the modulation of M1 corticospinal excitability induced by observation of others' actions. Recent brain imaging studies have revealed that viewing videos of grasping actions led to a differential activation of the ventral premotor cortex depending on whether the entire person is viewed versus only their disembodied hand. Here we used transcranial magnetic stimulation (TMS) to examine motor evoked potentials (MEPs) in the first dorsal interosseous (FDI) and abductor digiti minimi (ADM) during observation of videos or static images in which a whole person or merely the hand was seen reaching and grasping a peanut (precision grip) or an apple (whole hand grasp). Participants were presented with six visual conditions in which visual stimuli (video vs static image), view (whole person vs hand) and grasp (precision grip vs whole hand grasp) were varied in a 2 × 2 × 2 factorial design. Observing videos, but not static images, of a hand grasping different objects resulted in a grasp-specific interaction, such that FDI and ADM MEPs were differentially modulated depending on the type of grasp being observed (precision grip vs whole hand grasp). This interaction was present when observing the hand acting, but not when observing the whole person acting. Additional experiments revealed that these results were unlikely to be due to the relative size of the hand being observed. Our results suggest that observation of videos rather than static images is critical for motor resonance. Importantly, observing the whole person performing the action abolished the grasp-specific effect, which could be due to a variety of PMv inputs converging on M1. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

An eight-legged tactile sensor to estimate coefficient of static friction.

PubMed

Wei Chen; Rodpongpun, Sura; Luo, William; Isaacson, Nathan; Kark, Lauren; Khamis, Heba; Redmond, Stephen J

2015-08-01

It is well known that a tangential force larger than the maximum static friction force is required to initiate the sliding motion between two objects, which is governed by a material constant called the coefficient of static friction. Therefore, knowing the coefficient of static friction is of great importance for robot grippers which wish to maintain a stable and precise grip on an object during various manipulation tasks. Importantly, it is most useful if grippers can estimate the coefficient of static friction without having to explicitly explore the object first, such as lifting the object and reducing the grip force until it slips. A novel eight-legged sensor, based on simplified theoretical principles of friction is presented here to estimate the coefficient of static friction between a planar surface and the prototype sensor. Each of the sensor's eight legs are straight and rigid, and oriented at a specified angle with respect to the vertical, allowing it to estimate one of five ranges (5 = 8/2 + 1) that the coefficient of static friction can occupy. The coefficient of friction can be estimated by determining whether the legs have slipped or not when pressed against a surface. The coefficients of static friction between the sensor and five different materials were estimated and compared to a measurement from traditional methods. A least-squares linear fit of the sensor estimated coefficient showed good correlation with the reference coefficient with a gradient close to one and an r(2) value greater than 0.9.

Does the type of somatosensory information from the contralateral finger touch affect grip force control while lifting an object?

PubMed

Chen, Bing; Aruin, Alexander S

2013-11-27

The magnitude of grip force used to lift and transport a hand-held object is decreased if a light finger touch from the contralateral arm is provided to the wrist of the target arm. We investigated whether the type of contralateral arm sensory input that became available with the finger touch to the target arm affects the way grip force is reduced. Nine healthy subjects performed the same task of lifting and transporting an instrumented object with no involvement of the contralateral arm and when an index finger touch of the contralateral arm was provided to the wrist, elbow, and shoulder. Touching the wrist and elbow involved movements of the contralateral arm; no movements were produced while touching the shoulder. Grip force was reduced by approximately the same amount in all conditions with the finger touch compared to the no touch condition. This suggests that information from the muscle and joint receptors of the contralateral arm is used in control of grip force when a finger touch is provided to the wrist and elbow, and cutaneous information is utilized when lifting an object while touching the shoulder. The results of the study provide additional evidence to support the use of a second arm in the performance of activities of daily living and stress the importance of future studies investigating contralateral arm sensory input in grip force control. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Effects of transcranial direct current stimulation on the control of finger force during dexterous manipulation in healthy older adults.

PubMed

Parikh, Pranav J; Cole, Kelly J

2015-01-01

The contribution of poor finger force control to age-related decline in manual dexterity is above and beyond ubiquitous behavioral slowing. Altered control of the finger forces can impart unwanted torque on the object affecting its orientation, thus impairing manual performance. Anodal transcranial direct current stimulation (tDCS) over primary motor cortex (M1) has been shown to improve the performance speed on manual tasks in older adults. However, the effects of anodal tDCS over M1 on the finger force control during object manipulation in older adults remain to be fully explored. Here we determined the effects of anodal tDCS over M1 on the control of grip force in older adults while they manipulated an object with an uncertain mechanical property. Eight healthy older adults were instructed to grip and lift an object whose contact surfaces were unexpectedly made more or less slippery across trials using acetate and sandpaper surfaces, respectively. Subjects performed this task before and after receiving anodal or sham tDCS over M1 on two separate sessions using a cross-over design. We found that older adults used significantly lower grip force following anodal tDCS compared to sham tDCS. Friction measured at the finger-object interface remained invariant after anodal and sham tDCS. These findings suggest that anodal tDCS over M1 improved the control of grip force during object manipulation in healthy older adults. Although the cortical networks for representing objects and manipulative actions are complex, the reduction in grip force following anodal tDCS over M1 might be due to a cortical excitation yielding improved processing of object-specific sensory information and its integration with the motor commands for production of manipulative forces. Our findings indicate that tDCS has a potential to improve the control of finger force during dexterous manipulation in older adults.

Corticospinal neurons in macaque ventral premotor cortex with mirror properties: a potential mechanism for action suppression?

PubMed

Kraskov, Alexander; Dancause, Numa; Quallo, Marsha M; Shepherd, Samantha; Lemon, Roger N

2009-12-24

The discovery of "mirror neurons" in area F5 of the ventral premotor cortex has prompted many theories as to their possible function. However, the identity of mirror neurons remains unknown. Here, we investigated whether identified pyramidal tract neurons (PTNs) in area F5 of two adult macaques exhibited "mirror-like" activity. About half of the 64 PTNs tested showed significant modulation of their activity while monkeys observed precision grip of an object carried out by an experimenter, with somewhat fewer showing modulation during precision grip without an object or grasping concealed from the monkey. Therefore, mirror-like activity can be transmitted directly to the spinal cord via PTNs. A novel finding is that many PTNs (17/64) showed complete suppression of discharge during action observation, while firing actively when the monkey grasped food rewards. We speculate that this suppression of PTN discharge might be involved in the inhibition of self-movement during action observation. 2009 Elsevier Inc. All rights reserved.

Grip Force Coordination during Bimanual Tasks in Unilateral Cerebral Palsy

ERIC Educational Resources Information Center

Islam, Mominul; Gordon, Andrew M.; Skold, Annika; Forssberg, Hans; Eliasson, Ann-Christin

2011-01-01

Aim: The aim of the study was to investigate coordination of fingertip forces during an asymmetrical bimanual task in children with unilateral cerebral palsy (CP). Method: Twelve participants (six males, six females; mean age 14y 4mo, SD 3.3y; range 9-20y;) with unilateral CP (eight right-sided, four left-sided) and 15 age-matched typically…

The effect of workstation and task variables on forces applied during simulated meat cutting.

PubMed

McGorry, Raymond W; Dempsey, Patrick G; O'Brien, Niall V

2004-12-01

The purpose of the study was to investigate factors related to force and postural exposure during a simulated meat cutting task. The hypothesis was that workstation, tool and task variables would affect the dependent kinetic variables of gripping force, cutting moment and the dependent kinematic variables of elbow elevation and wrist angular displacement in the flexion/extension and radial/ulnar deviation planes. To evaluate this hypothesis a 3 x 3 x 2 x 2 x 2 (surface orientation by surface height by blade angle by cut complexity by work pace) within-subject factorial design was conducted with 12 participants. The results indicated that the variables can act and interact to modify the kinematics and kinetics of a cutting task. Participants used greater grip force and cutting moment when working at a pace based on productivity. The interactions of the work surface height and orientation indicated that the use of an adjustable workstation could minimize wrist deviation from neutral and improve shoulder posture during cutting operations. Angling the knife blade also interacted with workstation variables to improve wrist and upper extremity posture, but this benefit must be weighed against the potential for small increases in force exposure.

Predicting hand function in older adults: evaluations of grip strength, arm curl strength, and manual dexterity.

PubMed

Liu, Chiung-Ju; Marie, Deana; Fredrick, Aaron; Bertram, Jessica; Utley, Kristen; Fess, Elaine Ewing

2017-08-01

Hand function is critical for independence in activities of daily living for older adults. The purpose of this study was to examine how grip strength, arm curl strength, and manual dexterous coordination contributed to time-based versus self-report assessment of hand function in community-dwelling older adults. Adults aged ≥60 years without low vision or neurological disorders were recruited. Purdue Pegboard Test, Jamar hand dynamometer, 30-second arm curl test, Jebsen-Taylor Hand Function Test, and the Late-Life Function and Disability Instrument were administered to assess manual dexterous coordination, grip strength, arm curl strength, time-based hand function, and self-report of hand function, respectively. Eighty-four adults (mean age = 72 years) completed the study. Hierarchical multiple regressions show that older adults with better arm curl strength (β = -.25, p < .01) and manual dexterous coordination (β = -.52, p < .01) performed better on the time-based hand function test. In comparison, older adults with better grip strength (β = .40, p < .01), arm curl strength (β = .23, p < .05), and manual dexterous coordination (β = .23, p < .05) were associated with better self-report of upper extremity function. The relationship between grip strength and hand function may be test-specific. Grip strength becomes a significant factor when the test requires grip strength to successfully complete the test tasks. Arm curl strength independently contributed to hand function in both time-based and self-report assessments, indicating that strength of extrinsic muscles of the hand are essential for hand function.

Task-specificity of unilateral anodal and dual-M1 tDCS effects on motor learning.

PubMed

Karok, Sophia; Fletcher, David; Witney, Alice G

2017-01-08

Task-specific effects of transcranial direct current stimulation (tDCS) on motor learning were investigated in 30 healthy participants. In a sham-controlled, mixed design, participants trained on 3 different motor tasks (Purdue Pegboard Test, Visuomotor Grip Force Tracking Task and Visuomotor Wrist Rotation Speed Control Task) over 3 consecutive days while receiving either unilateral anodal over the right primary motor cortex (M1), dual-M1 or sham stimulation. Retention sessions were administered 7 and 28 days after the end of training. In the Purdue Pegboard Test, both anodal and dual-M1 stimulation reduced average completion time approximately equally, an improvement driven by online learning effects and maintained for about 1 week. The Visuomotor Grip Force Tracking Task and the Visuomotor Wrist Rotation Speed Control Task were associated with an advantage of dual-M1 tDCS in consolidation processes both between training sessions and when testing at long-term retention; both were maintained for at least 1 month. This study demonstrates that M1-tDCS enhances and sustains motor learning with different electrode montages. Stimulation-induced effects emerged at different learning phases across the tasks, which strongly suggests that the influence of tDCS on motor learning is dynamic with respect to the functional recruitment of the distributed motor system at the time of stimulation. Divergent findings regarding M1-tDCS effects on motor learning may partially be ascribed to task-specific consequences and the effects of offline consolidation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of grasping movements made by healthy subjects in a 3-dimensional immersive virtual versus physical environment.

PubMed

Magdalon, Eliane C; Michaelsen, Stella M; Quevedo, Antonio A; Levin, Mindy F

2011-09-01

Virtual reality (VR) technology is being used with increasing frequency as a training medium for motor rehabilitation. However, before addressing training effectiveness in virtual environments (VEs), it is necessary to identify if movements made in such environments are kinematically similar to those made in physical environments (PEs) and the effect of provision of haptic feedback on these movement patterns. These questions are important since reach-to-grasp movements may be inaccurate when visual or haptic feedback is altered or absent. Our goal was to compare kinematics of reaching and grasping movements to three objects performed in an immersive three-dimensional (3D) VE with haptic feedback (cyberglove/grasp system) viewed through a head-mounted display to those made in an equivalent physical environment (PE). We also compared movements in PE made with and without wearing the cyberglove/grasp haptic feedback system. Ten healthy subjects (8 women, 62.1±8.8years) reached and grasped objects requiring 3 different grasp types (can, diameter 65.6mm, cylindrical grasp; screwdriver, diameter 31.6mm, power grasp; pen, diameter 7.5mm, precision grasp) in PE and visually similar virtual objects in VE. Temporal and spatial arm and trunk kinematics were analyzed. Movements were slower and grip apertures were wider when wearing the glove in both the PE and the VE compared to movements made in the PE without the glove. When wearing the glove, subjects used similar reaching trajectories in both environments, preserved the coordination between reaching and grasping and scaled grip aperture to object size for the larger object (cylindrical grasp). However, in VE compared to PE, movements were slower and had longer deceleration times, elbow extension was greater when reaching to the smallest object and apertures were wider for the power and precision grip tasks. Overall, the differences in spatial and temporal kinematics of movements between environments were greater than those due only to wearing the cyberglove/grasp system. Differences in movement kinematics due to the viewing environment were likely due to a lack of prior experience with the virtual environment, an uncertainty of object location and the restricted field-of-view when wearing the head-mounted display. The results can be used to inform the design and disposition of objects within 3D VEs for the study of the control of prehension and for upper limb rehabilitation. Copyright © 2011 Elsevier B.V. All rights reserved.

Evidence for Motor Planning in Monkeys: Rhesus Macaques Select Efficient Grips when Transporting Spoons

ERIC Educational Resources Information Center

Nelson, Eliza L.; Berthier, Neil E.; Metevier, Christina M.; Novak, Melinda A.

2011-01-01

McCarty and colleagues (1999) developed the elevated spoon task to measure motor planning in human infants. In this task, a spoon containing food was placed on an elevated apparatus that supported both ends of the spoon. The handle was oriented to the left or right on different trials. We presented naive adult rhesus monkeys (Macaca mulatta) with…

Influence of finger and mouth action observation on random number generation: an instance of embodied cognition for abstract concepts.

PubMed

Grade, Stéphane; Badets, Arnaud; Pesenti, Mauro

2017-05-01

Numerical magnitude and specific grasping action processing have been shown to interfere with each other because some aspects of numerical meaning may be grounded in sensorimotor transformation mechanisms linked to finger grip control. However, how specific these interactions are to grasping actions is still unknown. The present study tested the specificity of the number-grip relationship by investigating how the observation of different closing-opening stimuli that might or not refer to prehension-releasing actions was able to influence a random number generation task. Participants had to randomly produce numbers after they observed action stimuli representing either closure or aperture of the fingers, the hand or the mouth, or a colour change used as a control condition. Random number generation was influenced by the prior presentation of finger grip actions, whereby observing a closing finger grip led participants to produce small rather than large numbers, whereas observing an opening finger grip led them to produce large rather than small numbers. Hand actions had reduced or no influence on number production; mouth action influence was restricted to opening, with an overproduction of large numbers. Finally, colour changes did not influence number generation. These results show that some characteristics of observed finger, hand and mouth grip actions automatically prime number magnitude, with the strongest effect for finger grasping. The findings are discussed in terms of the functional and neural mechanisms shared between hand actions and number processing, but also between hand and mouth actions. The present study provides converging evidence that part of number semantics is grounded in sensory-motor mechanisms.

Pneumatic-type surgical robot end-effector for laparoscopic surgical-operation-by-wire.

PubMed

Lee, Chiwon; Park, Woo Jung; Kim, Myungjoon; Noh, Seungwoo; Yoon, Chiyul; Lee, Choonghee; Kim, Youdan; Kim, Hyeon Hoe; Kim, Hee Chan; Kim, Sungwan

2014-09-05

Although minimally invasive surgery (MIS) affords several advantages compared to conventional open surgery, robotic MIS systems still have many limitations. One of the limitations is the non-uniform gripping force due to mechanical strings of the existing systems. To overcome this limitation, a surgical instrument with a pneumatic gripping system consisting of a compressor, catheter balloon, micro motor, and other parts is developed. This study aims to implement a surgical instrument with a pneumatic gripping system and pitching/yawing joints using micro motors and without mechanical strings based on the surgical-operation-by-wire (SOBW) concept. A 6-axis external arm for increasing degrees of freedom (DOFs) is integrated with the surgical instrument using LabVIEW® for laparoscopic procedures. The gripping force is measured over a wide range of pressures and compared with the simulated ideal step function. Furthermore, a kinematic analysis is conducted. To validate and evaluate the system's clinical applicability, a simple peg task experiment and workspace identification experiment are performed with five novice volunteers using the fundamentals of laparoscopic surgery (FLS) board kit. The master interface of the proposed system employs the hands-on-throttle-and-stick (HOTAS) controller used in aerospace engineering. To develop an improved HOTAS (iHOTAS) controller, 6-axis force/torque sensor was integrated in the special housing. The mean gripping force (after 1,000 repetitions) at a pressure of 0.3 MPa was measured to be 5.8 N. The reaction time was found to be 0.4 s, which is almost real-time. All novice volunteers could complete the simple peg task within a mean time of 176 s, and none of them exceeded the 300 s cut-off time. The system's workspace was calculated to be 11,157.0 cm3. The proposed pneumatic gripping system provides a force consistent with that of other robotic MIS systems. It provides near real-time control. It is more durable than the existing other surgical robot systems. Its workspace is sufficient for clinical surgery. Therefore, the proposed system is expected to be widely used for laparoscopic robotic surgery. This research using iHOTAS will be applied to the tactile force feedback system for surgeon's safe operation.

Getting a Grip on Social Gaze: Control over Others' Gaze Helps Gaze Detection in High-Functioning Autism

ERIC Educational Resources Information Center

Dratsch, Thomas; Schwartz, Caroline; Yanev, Kliment; Schilbach, Leonhard; Vogeley, Kai; Bente, Gary

2013-01-01

We investigated the influence of control over a social stimulus on the ability to detect direct gaze in high-functioning autism (HFA). In a pilot study, 19 participants with and 19 without HFA were compared on a gaze detection and a gaze setting task. Participants with HFA were less accurate in detecting direct gaze in the detection task, but did…

Corticospinal integrity and motor impairment predict outcomes after excitatory repetitive transcranial magnetic stimulation: a preliminary study.

PubMed

Lai, Chih-Jou; Wang, Chih-Pin; Tsai, Po-Yi; Chan, Rai-Chi; Lin, Shan-Hui; Lin, Fu-Gong; Hsieh, Chin-Yi

2015-01-01

To identify the effective predictors for therapeutic outcomes based on intermittent theta-burst stimulation (iTBS). A sham-controlled, double-blind parallel study design. A tertiary hospital. People with stroke (N=72) who presented with unilateral hemiplegia. Ten consecutive sessions of real or sham iTBS were implemented with the aim of enhancing hand function. Patients were categorized into 4 groups according to the presence (MEP+) or absence (MEP-) of motor-evoked potentials (MEPs) and grip strength according to the Medical Research Council (MRC) scale. Cortical excitability, Wolf Motor Function Test (WMFT), finger-tapping task (FT), and simple reaction time were performed before and after the sessions. MEPs and the MRC scale were predictive of iTBS therapeutic outcomes. Group A (MEP+, MRC>1) exhibited the greatest WMFT change (7.6±2.3, P<.001), followed by group B (MEP-, MRC>1; 5.2±2.2 score change) and group C (MEP-, MRC=0; 2.3±1.5 score change). These improvements were correlated significantly with baseline motor function and ipsilesional maximum MEP amplitude. The effectiveness of iTBS modulation for poststroke motor enhancement depends on baseline hand grip strength and the presence of MEPs. Our findings indicate that establishing neurostimulation strategies based on the proposed electrophysiological and clinical criteria can allow iTBS to be executed with substantial precision. Effective neuromodulatory strategies can be formulated by using electrophysiological features and clinical presentation information as guidelines. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Anticipatory planning and control of grasp positions and forces for dexterous two-digit manipulation.

PubMed

Fu, Qiushi; Zhang, Wei; Santello, Marco

2010-07-07

Dexterous object manipulation requires anticipatory control of digit positions and forces. Despite extensive studies on sensorimotor learning of digit forces, how humans learn to coordinate digit positions and forces has never been addressed. Furthermore, the functional role of anticipatory modulation of digit placement to object properties remains to be investigated. We addressed these questions by asking human subjects (12 females, 12 males) to grasp and lift an inverted T-shaped object using precision grip at constrained or self-chosen locations. The task requirement was to minimize object roll during lift. When digit position was not constrained, subjects could have implemented many equally valid digit position-force coordination patterns. However, choice of digit placement might also have resulted in large trial-to-trial variability of digit position, hence challenging the extent to which the CNS could have relied on sensorimotor memories for anticipatory control of digit forces. We hypothesized that subjects would modulate digit placement for optimal force distribution and digit forces as a function of variable digit positions. All subjects learned to minimize object roll within the first three trials, and the unconstrained device was associated with significantly smaller grip forces but larger variability of digit positions. Importantly, however, digit load force modulation compensated for position variability, thus ensuring consistent object roll minimization on each trial. This indicates that subjects learned object manipulation by integrating sensorimotor memories with sensory feedback about digit positions. These results are discussed in the context of motor equivalence and sensorimotor integration of grasp kinematics and kinetics.

A comparison of hand grasp breakaway strengths and bare-handed grip strengths of the astronauts, SML 3 test subjects, and the subjects from the general population

NASA Technical Reports Server (NTRS)

Rajulu, Sudhakar L.; Klute, Glenn K.

1993-01-01

Astronauts have the task of retrieving and deploying satellites and handling massive objects in a around the payload bay. Concerns were raised that manual handling of such massive objects might induce loads to the shuttle suits exceeding the design-certified loads. The Crew and Thermal Division of NASA JSC simulated the satellite handling tasks (Satellite Manload Tests 1 and 3) and determined the maximum possible load that a suited member could impart onto the suit. In addition, the tests revealed that the load to the suit by an astronaut could be calculated from the astronaut's maximum hand grasp breakaway strength. Thus, this study was conducted to document that hand grasp breakaway strengths of the astronauts who were scheduled to perform EVA during the upcoming missions. In addition, this study verified whether the SML 3 test results were sufficient for documenting the maximum possible load. An attempt was made to predict grasp strength from grip strength and hand anthropometry. Based on the results from this study, the SML 3 test results were deemed sufficient to document the maximum possible load on the suit. Finally, prediction of grasp strength from grip strength was not as accurate as expected. Hence, it was recommended that grasp strength be collected from the astronauts in order to obtain accurate load estimation.

Bimanual Force Coordination in Parkinson’s Disease Patients with Bilateral Subthalamic Deep Brain Stimulation

PubMed Central

Gorniak, Stacey L.; McIntyre, Cameron C.; Alberts, Jay L.

2013-01-01

Objective Studies of bimanual actions similar to activities of daily living (ADLs) are currently lacking in evaluating fine motor control in Parkinson’s disease patients implanted with bilateral subthalamic deep brain stimulators. We investigated basic time and force characteristics of a bimanual task that resembles performance of ADLs in a group of bilateral subthalamic deep brain stimulation (DBS) patients. Methods Patients were evaluated in three different DBS parameter conditions off stimulation, on clinically derived stimulation parameters, and on settings derived from a patient-specific computational model. Model-based parameters were computed as a means to minimize spread of current to non-motor regions of the subthalamic nucleus via Cicerone Deep Brain Stimulation software. Patients were evaluated off parkinsonian medications in each stimulation condition. Results The data indicate that DBS parameter state does not affect most aspects of fine motor control in ADL-like tasks; however, features such as increased grip force and grip symmetry varied with the stimulation state. In the absence of DBS parameters, patients exhibited significant grip force asymmetry. Overall UPDRS-III and UPDRS-III scores associated with hand function were lower while patients were experiencing clinically-derived or model-based parameters, as compared to the off-stimulation condition. Conclusion While bilateral subthalamic DBS has been shown to alleviate gross motor dysfunction, our results indicate that DBS may not provide the same magnitude of benefit to fine motor coordination. PMID:24244388

One day of motor training with amphetamine impairs motor recovery following spinal cord injury.

PubMed

Wong, Jamie K; Steward, Oswald

2012-02-01

It has previously been reported that a single dose of amphetamine paired with training on a beam walking task can enhance locomotor recovery following brain injury (Feeney et al., 1982). Here, we investigated whether this same drug/training regimen could enhance functional recovery following either thoracic (T9) or cervical (C5) spinal cord injury. Different groups of female Sprague-Dawley rats were trained on a beam walking task, and in a straight alley for assessment of hindlimb locomotor recovery using the BBB locomotor scale. For rats that received C5 hemisections, forelimb grip strength was assessed using a grip strength meter. Three separate experiments assessed the consequences of training rats on the beam walking task 24 h following a thoracic lateral hemisection with administration of either amphetamine or saline. Beginning 1 h following drug administration, rats either received additional testing/retraining on the beam hourly for 6 h, or they were returned to their home cages without further testing/retraining. Rats with thoracic spinal cord injuries that received amphetamine in conjunction with testing/retraining on the beam at 1 day post injury (DPI) exhibited significantly impaired recovery on the beam walking task and BBB. Rats with cervical spinal cord injuries that received training with amphetamine also exhibited significant impairments in beam walking and locomotion, as well as impairments in gripping and reaching abilities. Even when administered at 14 DPI, the drug/training regimen significantly impaired reaching ability in cervical spinal cord injured rats. Impairments were not seen in rats that received amphetamine without training. Histological analyses revealed that rats that received training with amphetamine had significantly larger lesions than saline controls. These data indicate that an amphetamine/training regimen that improves recovery after cortical injury has the opposite effect of impairing recovery following spinal cord injury because early training with amphetamine increases lesion severity. Copyright © 2011 Elsevier Inc. All rights reserved.

Coherent Multimodal Sensory Information Allows Switching between Gravitoinertial Contexts

PubMed Central

Barbiero, Marie; Rousseau, Célia; Papaxanthis, Charalambos; White, Olivier

2017-01-01

Whether the central nervous system is capable to switch between contexts critically depends on experimental details. Motor control studies regularly adopt robotic devices to perturb the dynamics of a certain task. Other approaches investigate motor control by altering the gravitoinertial context itself as in parabolic flights and human centrifuges. In contrast to conventional robotic experiments, where only the hand is perturbed, these gravitoinertial or immersive settings coherently plunge participants into new environments. However, radically different they are, perfect adaptation of motor responses are commonly reported. In object manipulation tasks, this translates into a good matching of the grasping force or grip force to the destabilizing load force. One possible bias in these protocols is the predictability of the forthcoming dynamics. Here we test whether the successful switching and adaptation processes observed in immersive environments are a consequence of the fact that participants can predict the perturbation schedule. We used a short arm human centrifuge to decouple the effects of space and time on the dynamics of an object manipulation task by adding an unnatural explicit position-dependent force. We created different dynamical contexts by asking 20 participants to move the object at three different paces. These contextual sessions were interleaved such that we could simulate concurrent learning. We assessed adaptation by measuring how grip force was adjusted to this unnatural load force. We found that the motor system can switch between new unusual dynamical contexts, as reported by surprisingly well-adjusted grip forces, and that this capacity is not a mere consequence of the ability to predict the time course of the upcoming dynamics. We posit that a coherent flow of multimodal sensory information born in a homogeneous milieu allows switching between dynamical contexts. PMID:28553233

Physical Ability-Task Performance Models: Assessing the Risk of Omitted Variable Bias

DTIC Science & Technology

2008-09-15

association was evaluated in a study of simulated job performance in men and women. The study measured four major abilities, Static Strength (SS), Dynamic...ability- performance interface for physical tasks. Methods Sample Participants were active-duty naval personnel (64 men , 38 women) between ages 20...bench with feet flat on the floor. Position was adjusted so the bar was between the shoulder and nipple line. Handles were gripped at a comfortable

Grip Forces During Object Manipulation: Experiment, Mathematical Model & Validation

PubMed Central

Slota, Gregory P.; Latash, Mark L.; Zatsiorsky, Vladimir M.

2011-01-01

When people transport handheld objects, they change the grip force with the object movement. Circular movement patterns were tested within three planes at two different rates (1.0, 1.5 Hz), and two diameters (20, 40 cm). Subjects performed the task reasonably well, matching frequencies and dynamic ranges of accelerations within expectations. A mathematical model was designed to predict the applied normal forces from kinematic data. The model is based on two hypotheses: (a) the grip force changes during movements along complex trajectories can be represented as the sum of effects of two basic commands associated with the parallel and orthogonal manipulation, respectively; (b) different central commands are sent to the thumb and virtual finger (Vf- four fingers combined). The model predicted the actual normal forces with a total variance accounted for of better than 98%. The effects of the two components of acceleration—along the normal axis and the resultant acceleration within the shear plane—on the digit normal forces are additive. PMID:21735245

Kriging modeling and SPSA adjusting PID with KPWF compensator control of IPMC gripper for mm-sized objects

NASA Astrophysics Data System (ADS)

Chen, Yang; Hao, Lina; Yang, Hui; Gao, Jinhai

2017-12-01

Ionic polymer metal composite (IPMC) as a new smart material has been widely concerned in the micromanipulation field. In this paper, a novel two-finger gripper which contains an IPMC actuator and an ultrasensitive force sensor is proposed and fabricated. The IPMC as one finger of the gripper for mm-sized objects can achieve gripping and releasing motion, and the other finger works not only as a support finger but also as a force sensor. Because of the feedback signal of the force sensor, this integrated actuating and sensing gripper can complete gripping miniature objects in millimeter scale. The Kriging model is used to describe nonlinear characteristics of the IPMC for the first time, and then the control scheme called simultaneous perturbation stochastic approximation adjusting a proportion integration differentiation parameter controller with a Kriging predictor wavelet filter compensator is applied to track the gripping force of the gripper. The high precision force tracking in the foam ball manipulation process is obtained on a semi-physical experimental platform, which demonstrates that this gripper for mm-sized objects can work well in manipulation applications.

Human-arm-and-hand-dynamic model with variability analyses for a stylus-based haptic interface.

PubMed

Fu, Michael J; Cavuşoğlu, M Cenk

2012-12-01

Haptic interface research benefits from accurate human arm models for control and system design. The literature contains many human arm dynamic models but lacks detailed variability analyses. Without accurate measurements, variability is modeled in a very conservative manner, leading to less than optimal controller and system designs. This paper not only presents models for human arm dynamics but also develops inter- and intrasubject variability models for a stylus-based haptic device. Data from 15 human subjects (nine male, six female, ages 20-32) were collected using a Phantom Premium 1.5a haptic device for system identification. In this paper, grip-force-dependent models were identified for 1-3-N grip forces in the three spatial axes. Also, variability due to human subjects and grip-force variation were modeled as both structured and unstructured uncertainties. For both forms of variability, the maximum variation, 95 %, and 67 % confidence interval limits were examined. All models were in the frequency domain with force as input and position as output. The identified models enable precise controllers targeted to a subset of possible human operator dynamics.

Evolution of the human hand: approaches to acquiring, analysing and interpreting the anatomical evidence

PubMed Central

MARZKE, MARY W.; MARZKE, R. F.

2000-01-01

The discovery of fossil hand bones from an early human ancestor at Olduvai Gorge in 1960, at the same level as primitive stone tools, generated a debate about the role of tools in the evolution of the human hand that has raged to the present day. Could the Olduvai hand have made the tools? Did the human hand evolve as an adaptation to tool making and tool use? The debate has been fueled by anatomical studies comparing living and fossil human and nonhuman primate hands, and by experimental observations. These have assessed the relative abilities of apes and humans to manufacture the Oldowan tools, but consensus has been hampered by disagreements about how to translate experimental data from living species into quantitative models for predicting the performance of fossil hands. Such models are now beginning to take shape as new techniques are applied to the capture, management and analysis of data on kinetic and kinematic variables ranging from hand joint structure, muscle mechanics, and the distribution and density of bone to joint movements and muscle recruitment during manipulative behaviour. The systematic comparative studies are highlighting a functional complex of features in the human hand facilitating a distinctive repertoire of grips that are apparently more effective for stone tool making than grips characterising various nonhuman primate species. The new techniques are identifying skeletal variables whose form may provide clues to the potential of fossil hominid hands for one-handed firm precision grips and fine precision manoeuvering movements, both of which are essential for habitual and effective tool making and tool use. PMID:10999274

A comparison of different vibration exercise techniques on neuromuscular performance.

PubMed

García-Gutiérrez, M T; Rhea, M R; Marín, P J

2014-09-01

The first purpose of this study was to determine the effects of whole-body vibration (WBV) exercise during an isometric hand-grip exercise. The second purpose was to evaluate whether more than one vibratory focus would evoke an increase in the effects evoked by only one vibratory focus. The present study investigated whether WBV exposure during 10 repetitions of a handgrip dynamometer while standing on a WBV platform. Twenty-eight recreationally active university students completed 3 different test conditions, in random order: 1) grip dynamometer exercise with superimposed WBV and contralateral arm vibration (WBV+AV); 2) superimposed arm vibration only (AV); 3) grip dynamometer exercise without vibration (Control). The hand grip strength was slightly higher in the WBV condition as compared to the Control and AV conditions (1.1% and 3.6%, p>0.05, respectively). A main effect of the EMGrms of extensor digitorum muscle (ED) was observed indicating that the WBV+AV condition produced a lower co-activation of ED during a flexor digital task than the Control and AV (p<0.05) conditions. The application of WBV+AV may acutely increase muscle coordination and decreases the coactivation of ED. Furthermore, the muscle EMGrms showed increases in activation near the vibratory focus in both upper- and lower-body.

Hand controllers for teleoperation. A state-of-the-art technology survey and evaluation

NASA Technical Reports Server (NTRS)

Brooks, T. L.; Bejczy, A. K.

1985-01-01

Hand controller technology for teleoperation is surveyed in three major catagories: (1) hand grip design, (2) control input devices, and (3) control strategies. In the first category, 14 hand grip designs are reviewed and evaluated in light of human factor considerations. In the second, 12 hand controller input devices are evaluated in terms of task performance, configuration and force feedback, controller/slave correspondence, operating volume, operator workload, human limitations, cross coupling, singularities, anthropomorphic characteristics, physical complexity, control/display interference, accuracy, technological base, cost, and reliability. In the third catagory, control strategies, commonly called control modes, are surveyed and evaluated. The report contains a bibliography with 189 select references on hand controller technology.

A New Deal for Higher Education?

ERIC Educational Resources Information Center

Roach, Ronald

2009-01-01

Almost a year after assuming leadership, the administration of Barack Obama has taken on enormous tasks in confronting the recession that has gripped the U.S. economy. Americans have watched tentatively as the president has extended federal powers into handling corporate bailouts, overseeing the rehabilitation of banks and General Motors, laying…

The impact of the Swedish massage on the kinesthetic differentiation in healthy individuals.

PubMed

Mustafa, Kamil; Furmanek, Mariusz Pawel; Knapik, Aleksandra; Bacik, Bogdan; Juras, Grzegorz

2015-03-01

Swedish massage is one of the common treatments to provide optimal start and readiness of athletes. The ability of kinesthetic differentiation (KD) is crucial in sport performance. This skill allows to adapt demanded muscle forces to optimize the motor tasks, and it is responsible for the precision. In the literature, there is no evidence how Swedish massage influences the kinesthetic differentiation. The objective of the study was to evaluate the impact of Swedish massage on the kinesthetic differentiation and muscle strength of hand grip. Thirty participants took part in this investigation (17 women and 13 men). The assessment consisted of KD tests conducted on the dominant (DH) and nondominant hand (NDH) after 15 minutes of hand and forearm Swedish massage. The procedure consisted of 13 trials for each extremity. The first three were done for 100% of the participants' capabilities (Fmax), the next five trials were done using 50% of maximum force (50% of Fmax), and in the last five trials, the participants tried to use only 50% of their previous force (1/2 of 50%). Finally, the absolute force production error (FPE) was calculated for 50% (FPE_50%) and 25% (FPE_25%). The two-way repeated measure analysis of variance ANOVA did not reveal any statistically significant changes in maximal strength grip and KD between pre- and postmassage intervention in both DH and NDH hand. Correlations showed strong relationship between pre- and postmassage for maximum force (r = 0.92, p = .01 for DH, and r = 0.94, p = .01 for NDH), and only for the FPE_50% (r = 0.67, p = .01 for DH, and r = 0.71, p = .01 for NDH). The results obtained indicated that the application of the Swedish massage did not affect the kinesthetic differentiation in this particular young adult group.

Learned Manipulation at Unconstrained Contacts Does Not Transfer across Hands

PubMed Central

Fu, Qiushi; Choi, Jason Y.; Gordon, Andrew M.; Jesunathadas, Mark; Santello, Marco

2014-01-01

Recent studies about sensorimotor control of the human hand have focused on how dexterous manipulation is learned and generalized. Here we address this question by testing the extent to which learned manipulation can be transferred when the contralateral hand is used and/or object orientation is reversed. We asked subjects to use a precision grip to lift a grip device with an asymmetrical mass distribution while minimizing object roll during lifting by generating a compensatory torque. Subjects were allowed to grasp anywhere on the object’s vertical surfaces, and were therefore able to modulate both digit positions and forces. After every block of eight trials performed in one manipulation context (i.e., using the right hand and at a given object orientation), subjects had to lift the same object in the second context for one trial (transfer trial). Context changes were made by asking subjects to switch the hand used to lift the object and/or rotate the object 180° about a vertical axis. Therefore, three transfer conditions, hand switch (HS), object rotation (OR), and both hand switch and object rotation (HS+OR), were tested and compared with hand matched control groups who did not experience context changes. We found that subjects in all transfer conditions adapted digit positions across multiple transfer trials similar to the learning of control groups, regardless of different changes of contexts. Moreover, subjects in both HS and HS+OR group also adapted digit forces similar to the control group, suggesting independent learning of the left hand. In contrast, the OR group showed significant negative transfer of the compensatory torque due to an inability to adapt digit forces. Our results indicate that internal representations of dexterous manipulation tasks may be primarily built through the hand used for learning and cannot be transferred across hands. PMID:25233091

Changes in kinetics and kinematics of handwriting during a prolonged writing task in children with and without dysgraphia.

PubMed

Kushki, Azadeh; Schwellnus, Heidi; Ilyas, Faizah; Chau, Tom

2011-01-01

Handwriting difficulties or dysgraphia have a profound impact on children's psychosocial development, and yet, 10-30% of school-aged children are reported to experience difficulties mastering this skill. Several studies have examined the nature and biomechanical underpinnings of handwriting difficulties in children with and without dysgraphia. While the majority of these studies have considered short handwriting activities involving a sentence or a paragraph, handwriting quality and speed are reported to vary with the length of the writing task. Further, it is suggested that the biomechanics of handwriting also evolve over extended writing periods, and that these changes may be distinct between children with and without dysgraphia. The nature and specificity of these biomechanical alterations remain unknown. To address this knowledge gap, we examined changes in writing speed, grip forces on the pen barrel, and normal forces on the writing surface, over the course of a 10-min writing task, in a large cohort of 4th grade children with and without dysgraphia. Horizontal stroke speed, grip force and normal force increased over time while vertical stroke speed decreased in all children. These biomechanical changes may be attributable to physical and psychological fatigue and the corresponding compensatory processes invoked by the motor system. Copyright © 2011 Elsevier Ltd. All rights reserved.

Hand shape selection in pantomimed grasping: Interaction between the dorsal and the ventral visual streams and convergence on the ventral premotor area

PubMed Central

Makuuchi, Michiru; Someya, Yoshiaki; Ogawa, Seiji; Takayama, Yoshihiro

2011-01-01

In visually guided grasping, possible hand shapes are computed from the geometrical features of the object, while prior knowledge about the object and the goal of the action influence both the computation and the selection of the hand shape. We investigated the system dynamics of the human brain for the pantomiming of grasping with two aspects accentuated. One is object recognition, with the use of objects for daily use. The subjects mimed grasping movements appropriate for an object presented in a photograph either by precision or power grip. The other is the selection of grip hand shape. We manipulated the selection demands for the grip hand shape by having the subjects use the same or different grip type in the second presentation of the identical object. Effective connectivity analysis revealed that the increased selection demands enhance the interaction between the anterior intraparietal sulcus (AIP) and posterior inferior temporal gyrus (pITG), and drive the converging causal influences from the AIP, pITG, and dorsolateral prefrontal cortex to the ventral premotor area (PMv). These results suggest that the dorsal and ventral visual areas interact in the pantomiming of grasping, while the PMv integrates the neural information of different regions to select the hand posture. The present study proposes system dynamics in visually guided movement toward meaningful objects, but further research is needed to examine if the same dynamics is found also in real grasping. PMID:21739528

Grasp movement decoding from premotor and parietal cortex.

PubMed

Townsend, Benjamin R; Subasi, Erk; Scherberger, Hansjörg

2011-10-05

Despite recent advances in harnessing cortical motor-related activity to control computer cursors and robotic devices, the ability to decode and execute different grasping patterns remains a major obstacle. Here we demonstrate a simple Bayesian decoder for real-time classification of grip type and wrist orientation in macaque monkeys that uses higher-order planning signals from anterior intraparietal cortex (AIP) and ventral premotor cortex (area F5). Real-time decoding was based on multiunit signals, which had similar tuning properties to cells in previous single-unit recording studies. Maximum decoding accuracy for two grasp types (power and precision grip) and five wrist orientations was 63% (chance level, 10%). Analysis of decoder performance showed that grip type decoding was highly accurate (90.6%), with most errors occurring during orientation classification. In a subsequent off-line analysis, we found small but significant performance improvements (mean, 6.25 percentage points) when using an optimized spike-sorting method (superparamagnetic clustering). Furthermore, we observed significant differences in the contributions of F5 and AIP for grasp decoding, with F5 being better suited for classification of the grip type and AIP contributing more toward decoding of object orientation. However, optimum decoding performance was maximal when using neural activity simultaneously from both areas. Overall, these results highlight quantitative differences in the functional representation of grasp movements in AIP and F5 and represent a first step toward using these signals for developing functional neural interfaces for hand grasping.

Evaluation of the Rotational Throttle Interface for Converting Aircraft Utilizing the NASA Ames Vertical Motion Simulator

NASA Technical Reports Server (NTRS)

Rozovski, David; Theodore, Colin R.

2011-01-01

An experiment was conducted to compare a conventional helicopter Thrust Control Lever (TCL) to the Rotational Throttle Interface (RTI) for tiltrotor aircraft. The RTI is designed to adjust its orientation to match the angle of the tiltrotor s nacelles. The underlying principle behind the design is to increase pilot awareness of the vehicle s configuration state (i.e. nacelle angle). Four test pilots flew multiple runs on seven different experimental courses. Three predominant effects were discovered in the testing of the RTI: 1. Unintentional binding along the control axis resulted in difficulties with precision power setting, 2. Confusion in which way to move the throttle grip was present during RTI transition modes, and 3. Pilots were not able to distinguish small angle differences during RTI transition. In this experiment the pilots were able to successfully perform all of the required tasks with both inceptors although the handling qualities ratings were slightly worse for the RTI partly due to unforeseen deficiencies in the design. Pilots did however report improved understanding of nacelle movement during transitions with the RTI.

Motor planning in different grasping tasks by capuchin monkeys (Sapajus spp.).

PubMed

Sabbatini, Gloria; Meglio, Giusy; Truppa, Valentina

2016-10-01

Studies on motor planning and action selection in object use reveal that what we choose to do in the present moment depends on our next planned action. In particular, many studies have shown that adult humans initially adopt uncomfortable hand postures to accommodate later task demands (i.e., the end-state comfort effect). Recent studies on action planning in different non-human primates species have provided contrasting results. Here, we tested whether capuchin monkeys (Sapajus spp.), natural tool users, would show planning abilities in two tasks with varying complexity: (i) an object-retrieval task involving self-directed actions (Experiment 1) and (ii) a tool-using task involving actions directed toward an external target (Experiment 2). In Experiment 1, six of 10 monkeys preferentially used a radial grip (i.e., with the thumb-side oriented towards the baited end) to grasp a horizontal dowel with either the left- or right-end baited and bring it to their mouth. In Experiment 2, all six tested capuchins preferentially used a radial grip (i.e., with the thumb-side oriented towards the center of the dowel) to grasp a dowel that was positioned horizontally at different orientations and to dislodge an out-of-reach food reward. Thus, we found that the capuchins showed second-order planning abilities in both tasks, but performance differences emerged in relation to hand preference and learning across sessions. Our findings support the idea that second-order motor planning occurred in an early stage of the primate lineage. Factors affecting the ability of nonhuman primates to estimate motor costs in action selection are discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

The brain adjusts grip forces differently according to gravity and inertia: a parabolic flight experiment

PubMed Central

White, Olivier

2015-01-01

In everyday life, one of the most frequent activities involves accelerating and decelerating an object held in precision grip. In many contexts, humans scale and synchronize their grip force (GF), normal to the finger/object contact, in anticipation of the expected tangential load force (LF), resulting from the combination of the gravitational and the inertial forces. In many contexts, GF and LF are linearly coupled. A few studies have examined how we adjust the parameters–gain and offset–of this linear relationship. However, the question remains open as to how the brain adjusts GF regardless of whether LF is generated by different combinations of weight and inertia. Here, we designed conditions to generate equivalent magnitudes of LF by independently varying mass and movement frequency. In a control experiment, we directly manipulated gravity in parabolic flights, while other factors remained constant. We show with a simple computational approach that, to adjust GF, the brain is sensitive to how LFs are produced at the fingertips. This provides clear evidence that the analysis of the origin of LF is performed centrally, and not only at the periphery. PMID:25717293

Study on functional relationships between ergonomics indexes of manual performance

NASA Astrophysics Data System (ADS)

Hu, Hui-Min; Ding, Li; Chen, Shou-Ping; Yang, Chun-Xin; Yuan, Xiu-Gan

This paper investigates functional relationships between some of the key ergonomics indexes in manual performance, and attempts to condense the ergonomics appraisal indexes system and thus evaluate hand performance wearing EVA (extravehicular activity) glove, design and improve EVA glove's performance. Four types of ergonomics indexes were studied, i.e., dexterity, tactile sensibility (TS), strength and fatigue. Two test items of insert sticks into a holes-board (ISIHB) and nuts-bolts assembly task (NBAT) were used to measure dexterity, while shape discrimination (SD) was employed for TS, and grip force (GF) for strength and fatigue. The variables measured in this investigation included accomplishing time (AT) of ISIHB and NBAT, correct rate (CR) of SD, maximal grip force (MGF), instant grip force (IGF) and endurance time of grip force (ETGF). Experiments were conducted on 31 undergraduates (eight female and 23 male) with two experiment conditions of bare-hand group and gloved hand group. Results demonstrated that dexterity and TS performance of gloved hand group declined significantly compared with those of bare-hand group (p<0.001). There were not significant differences in strength and fatigue between two conditions (p>0.05). Four effective functional relationships were developed between four pairs of ergonomics indexes in bare-hand group. In gloved hand group, in addition to above-mentioned four pairs of relationships, another formula was found, which was y^=0.02061+0.01233x ( p<0.01, dexterity and TS).

EVIDENCE FOR MOTOR PLANNING IN MONKEYS: RHESUS MACAQUES SELECT EFFICIENT GRIPS WHEN TRANSPORTING SPOONS

PubMed Central

Nelson, Eliza L.; Berthier, Neil E.; Metevier, Christina M.; Novak, Melinda A.

2014-01-01

McCarty and colleagues (1999) developed the elevated spoon task to measure motor planning in human infants. In this task, a spoon containing food was placed on an elevated apparatus that supported both ends of the spoon. The handle was oriented to the left or right on different trials. We presented naïve adult rhesus monkeys (Macaca mulatta) with the elevated spoon problem, and observed how monkeys learned the affordances of spoons over sessions. Strikingly, monkeys developed two different strategies for efficient spoon transport in just 12 to 36 trials. In subsequent testing with a novel double bowl spoon approximately 1 year later, monkeys demonstrated that they were attending to the baited spoon bowl and continued to select efficient grips for transporting the spoon. Monkey data were contrasted with previous studies in human infants using a perception-action perspective in an effort to understand the fundamentals of tool use and motor planning that may be common in the development of these abilities across species and their origins in human behavior. PMID:21676101

Injury Risk Assessment of Extravehicular Mobility Unit (EMU) Phase VI and Series 4000 Gloves During Extravehicular Activity (EVA) Hand Manipulation Tasks

NASA Technical Reports Server (NTRS)

Kilby, Melissa

2015-01-01

Functional Extravehicular Mobility Units (EMUs) with high precision gloves are essential for the success of Extravehicular Activity (EVA). Previous research done at NASA has shown that total strength capabilities and performance are reduced when wearing a pressurized EMU. The goal of this project was to characterize the human-space suit glove interaction and assess the risk of injury during common EVA hand manipulation tasks, including pushing, pinching and gripping objects. A custom third generation sensor garment was designed to incorporate a combination of sensors, including force sensitive resistors, strain gauge sensors, and shear force sensors. The combination of sensors was used to measure the forces acting on the finger nails, finger pads, finger tips, as well as the knuckle joints. In addition to measuring the forces, data was collected on the temperature, humidity, skin conductance, and blood perfusion of the hands. Testing compared both the Phase VI and Series 4000 glove against an ungloved condition. The ungloved test was performed wearing the sensor garment only. The project outcomes identified critical landmarks that experienced higher workloads and are more likely to suffer injuries. These critical landmarks varied as a function of space suit glove and task performed. The results showed that less forces were acting on the hands while wearing the Phase VI glove as compared to wearing the Series 4000 glove. Based on our findings, the engineering division can utilize these methods for optimizing the current space suit glove and designing next generation gloves to prevent injuries and optimize hand mobility and comfort.

Comparative morphology of the pollical distal phalanx.

PubMed

Shrewsbury, M M; Marzke, M W; Linscheid, R L; Reece, S P

2003-05-01

Functional analysis of human pollical distal phalangeal (PDP) morphology is undertaken to establish a basis for the assessment of fossil hominid PDP morphology. Features that contribute to the effectiveness of grips involving the distal thumb and finger pulp areas include: 1) distal thumb interphalangeal joint morphology, facilitating PDP conjunct pronation with flexion; 2) differentiation of a proximal, mobile pulp region from a distal, stable pulp region, providing for firm precision pinch grips and precision handling of objects; and 3) asymmetric attachment of the flexor pollicis longus (FPL) tendon fibers, favoring PDP conjunct pronation. A proportionately larger size of the ulnar vs. radial ungual spine suggests differential loading intensity of the ulnar side of the proximal ungual pulp and supporting nail bed. Stresses at the distal interphalangeal joint are indicated by the presence of a sesamoid bone within the volar (palmar) plate, which also increases the length of the flexor pollicis longus tendon moment arm. Dissections of specimens from six nonhuman primate genera indicate that these human features are shared variably with individuals in other species, although the full pattern of features appears to be distinctively human. Humans share variably with these other species all metric relationships examined here. The new data identify a need to systematically review long-standing assumptions regarding the range of precision and power manipulative capabilities that might reasonably be inferred from morphology of the distal phalangeal tuberosity and from the FPL tendon insertion site on the PDP. Copyright 2003 Wiley-Liss, Inc.

Decoding a wide range of hand configurations from macaque motor, premotor, and parietal cortices.

PubMed

Schaffelhofer, Stefan; Agudelo-Toro, Andres; Scherberger, Hansjörg

2015-01-21

Despite recent advances in decoding cortical activity for motor control, the development of hand prosthetics remains a major challenge. To reduce the complexity of such applications, higher cortical areas that also represent motor plans rather than just the individual movements might be advantageous. We investigated the decoding of many grip types using spiking activity from the anterior intraparietal (AIP), ventral premotor (F5), and primary motor (M1) cortices. Two rhesus monkeys were trained to grasp 50 objects in a delayed task while hand kinematics and spiking activity from six implanted electrode arrays (total of 192 electrodes) were recorded. Offline, we determined 20 grip types from the kinematic data and decoded these hand configurations and the grasped objects with a simple Bayesian classifier. When decoding from AIP, F5, and M1 combined, the mean accuracy was 50% (using planning activity) and 62% (during motor execution) for predicting the 50 objects (chance level, 2%) and substantially larger when predicting the 20 grip types (planning, 74%; execution, 86%; chance level, 5%). When decoding from individual arrays, objects and grip types could be predicted well during movement planning from AIP (medial array) and F5 (lateral array), whereas M1 predictions were poor. In contrast, predictions during movement execution were best from M1, whereas F5 performed only slightly worse. These results demonstrate for the first time that a large number of grip types can be decoded from higher cortical areas during movement preparation and execution, which could be relevant for future neuroprosthetic devices that decode motor plans. Copyright © 2015 the authors 0270-6474/15/351068-14$15.00/0.

How do C6/C7 tetraplegic patients grasp balls of different sizes and weights? Impact of surgical musculo-tendinous transfers.

PubMed

Laffont, I; Hoffmann, G; Dizien, O; Revol, M; Roby-Brami, A

2007-07-01

Prospective control cohort study. To develop a new test to analyse qualitatively grasping strategies in C6/C7 tetraplegic patients, and to quantify the effect of musculo-tendinous transfers. France. Twelve C6/C7 tetraplegic adults (17 arms; 31.3+/-7.9 years) and 17 healthy subjects (30.9+/-9.4 years) completed the study. We assessed participants' ability to grasp, move and release standardized balls of variable sizes and weights. Failures, movement duration (MD), grip patterns, forearm orientation during transport. In patients as well as in controls, the number of digits involved in prehension increased proportionally to the size and weight of the ball. C6 non-operated tetraplegic patients failed 38.2% of the tasks. They frequently used supine transport (51.4% of successful tasks). MD was longer, with a large distribution of values. The presence of active elbow extension poorly influenced the amount of failure nor grip configuration, but significantly reduced MD and supine transport (34%). Patients who were evaluated after hand surgery showed a trend towards improved MD and more frequent completion (failure 30%), especially for middle-sized and middle-weighted balls. Grip patterns were deeply modified, and all transports were made in pronation. The 'Tetra Ball Test' evidences the characteristics of grasping in tetraplegic patients and those influenced by surgery. It may be useful in understanding effects of surgical procedures. This preliminary study must be completed to evaluate the quantitative responsiveness and reproducibility of this test and to develop instrumented electronic balls to optimise it.

Task-relevant cognitive and motor functions are prioritized during prolonged speed-accuracy motor task performance.

PubMed

Solianik, Rima; Satas, Andrius; Mickeviciene, Dalia; Cekanauskaite, Agne; Valanciene, Dovile; Majauskiene, Daiva; Skurvydas, Albertas

2018-06-01

This study aimed to explore the effect of prolonged speed-accuracy motor task on the indicators of psychological, cognitive, psychomotor and motor function. Ten young men aged 21.1 ± 1.0 years performed a fast- and accurate-reaching movement task and a control task. Both tasks were performed for 2 h. Despite decreased motivation, and increased perception of effort as well as subjective feeling of fatigue, speed-accuracy motor task performance improved during the whole period of task execution. After the motor task, the increased working memory function and prefrontal cortex oxygenation at rest and during conflict detection, and the decreased efficiency of incorrect response inhibition and visuomotor tracking were observed. The speed-accuracy motor task increased the amplitude of motor-evoked potentials, while grip strength was not affected. These findings demonstrate that to sustain the performance of 2-h speed-accuracy task under conditions of self-reported fatigue, task-relevant functions are maintained or even improved, whereas less critical functions are impaired.

Determinants explaining the variability of hand-transmitted vibration emissions from two different work tasks: grinding and cutting using angle grinders.

PubMed

Liljelind, Ingrid; Pettersson, Hans; Nilsson, Leif; Wahlström, Jens; Toomingas, Allan; Lundström, Ronnie; Burström, Lage

2013-10-01

There are numerous factors including physical, biomechanical, and individual that influence exposure to hand-transmitted vibration (HTV) and cause variability in the exposure measurements. Knowledge of exposure variability and determinants of exposure could be used to improve working conditions. We performed a quasi-experimental study, where operators performed routine work tasks in order to obtain estimates of the variance components and to evaluate the effect of determinants, such as machine-wheel combinations and individual operator characteristics. Two pre-defined simulated work tasks were performed by 11 operators: removal of a weld puddle of mild steel and cutting of a square steel pipe. In both tasks, four angle grinders were used, two running on compressed air and two electrically driven. Two brands of both grinding and cutting wheels were used. Each operator performed both tasks twice in a random order with each grinder and wheel and the time to complete each task was recorded. Vibration emission values were collected and the wheel wear was measured as loss of weight. Operators' characteristics collected were as follows: age, body height and weight, length and volume of their hands, maximum hand grip force, and length of work experience with grinding machines (years). The tasks were also performed by one operator who used four machines of the same brand. Mixed and random effects models were used in the statistical evaluation. The statistical evaluation was performed for grinding and cutting separately and we used a measure referring to the sum of the 1-s r.m.s. average frequency-weighted acceleration over time for completing the work task (a(sa)). Within each work task, there was a significant effect as a result of the determinants 'the machine used', 'wheel wear', and 'time taken to complete the task'. For cutting, 'the brand of wheel' used also had a significant effect. More than 90% of the inherent variability in the data was explained by the determinants. The two electrically powered machines had a mean a(sa) that was 2.6 times higher than the two air-driven machines. For cutting, the effect of the brand of wheel on a(sa) was ~0.1 times. The a(sa) increased both with increasing wheel wear and with time taken to complete the work task. However, there were also a number of interaction effects which, to a minor extent, modified the a(sa). Only a minor part (1%) of the total variability was attributed to the operator: for cutting, the volume of the hands, maximum grip force, and body weight were significant, while for grinding, it was the maximum grip force. There was no clear difference in a(sa) between the four copies of the same brand of each machine. By including determinants that were attributed to the brand of both machine and wheel used as well as the time taken to complete the work task, we were able to explain >90% of the variability. The dominating determinant was the brand of the machine. Little variability was found between operators, indicating that the overall effect as due to the operator was small.

Motor Prediction at the Edge of Instability: Alteration of Grip Force Control during Changes in Bimanual Coordination

ERIC Educational Resources Information Center

Danion, Frederic; Jirsa, Viktor K.

2010-01-01

Predicting the consequences of actions is fundamental for skilled motor behavior. We investigated whether motor prediction is influenced by the fact that some movements are easier to perform and stabilize than others. Twelve subjects performed a bimanual rhythmical task either symmetrically or asymmetrically (the latter being more difficult and…

The influence of a real job on upper limb performance in motor skill tests: which abilities are transferred?

PubMed

Giangiardi, Vivian Farahte; Alouche, Sandra Regina; de Freitas, Sandra Maria Sbeghen Ferreira; Pires, Raquel Simoni; Padula, Rosimeire Simprini

2018-06-01

To investigate whether the specificities of real jobs create distinctions in the performance of workers in different motor tests for the upper limbs, 24 participants were divided into two groups according to their specific job: fine and repetitive tasks and general tasks. Both groups reproduced tasks related to aiming movements, handling and strength of the upper limbs. There were no significant differences between groups in the dexterity and performance of aiming movements. However, the general tasks group had higher grip strength than the repetitive tasks group, demonstrating differences according to job specificity. The results suggest that a particular motor skill in a specific job cannot improve performance in other tasks with the same motor requirements. The transfer of the fine and gross motor skills from previous experience in a job-specific task is the basis for allocating training and guidance to workers.

A soft and dexterous motor

NASA Astrophysics Data System (ADS)

Anderson, Iain A.; Tse, Tony Chun Hin; Inamura, Tokushu; O'Brien, Benjamin M.; McKay, Thomas; Gisby, Todd

2011-03-01

We present a soft, bearing-free artificial muscle motor that cannot only turn a shaft but also grip and reposition it through a flexible gear. The bearing-free operation provides a foundation for low complexity soft machines, with multiple degree-of-freedom actuation, that can act simultaneously as motors and manipulators. The mechanism also enables an artificial muscle controlled gear change. Future work will include self-sensing feedback for precision, multidegree-of-freedom operation.

Prosthetic Hand With Two Gripping Fingers

NASA Technical Reports Server (NTRS)

Norton, William E.; Belcher, Jewell B.; Vest, Thomas W.; Carden, James R.

1993-01-01

Prosthetic hand developed for amputee who retains significant portion of forearm. Outer end of device is end effector including two fingers, one moved by rotating remaining part of forearm about its longitudinal axis. Main body of end effector is end member supporting fingers, roller bearing assembly, and rack-and-pinion mechanism. Advantage of rack-and-pinion mechanism enables user to open or close gap between fingers with precision and force.

The impact of unilateral brain damage on anticipatory grip force scaling when lifting everyday objects.

PubMed

Eidenmüller, S; Randerath, J; Goldenberg, G; Li, Y; Hermsdörfer, J

2014-08-01

The scaling of our finger forces according to the properties of manipulated objects is an elementary prerequisite of skilled motor behavior. Lesions of the motor-dominant left brain may impair several aspects of motor planning. For example, limb-apraxia, a tool-use disorder after left brain damage is thought to be caused by deficient recall or integration of tool-use knowledge into an action plan. The aim of the present study was to investigate whether left brain damage affects anticipatory force scaling when lifting everyday objects. We examined 26 stroke patients with unilateral brain damage (16 with left brain damage, ten with right brain damage) and 21 healthy control subjects. Limb apraxia was assessed by testing pantomime of familiar tool-use and imitation of meaningless hand postures. Participants grasped and lifted twelve randomly presented everyday objects. Grip force was measured with help of sensors fixed on thumb, index and middle-finger. The maximum rate of grip force was determined to quantify the precision of anticipation of object properties. Regression analysis yielded clear deficits of anticipation in the group of patients with left brain damage, while the comparison of patient with right brain damage with their respective control group did not reveal comparable deficits. Lesion-analyses indicate that brain structures typically associated with a tool-use network in the left hemisphere play an essential role for anticipatory grip force scaling, especially the left inferior frontal gyrus (IFG) and the premotor cortex (PMC). Furthermore, significant correlations of impaired anticipation with limb apraxia scores suggest shared representations. However, the presence of dissociations, implicates also independent processes. Overall, our findings suggest that the left hemisphere is engaged in anticipatory grip force scaling for lifting everyday objects. The underlying neural substrate is not restricted to a single region or stream; instead it may rely on the intact functioning of a left hemisphere network that may overlap with the left hemisphere dominant tool-use network. Copyright © 2014 Elsevier Ltd. All rights reserved.

KENNEDY SPACE CENTER, FLA. - In KSC's Vertical Processing Facility, Louise Kleba of the Vehicle Integration Test Team (VITT) and engineer Devin Tailor of Goddard Space Flight Center examine the Pistol Grip Tool (PGT), which was designed for use by astronauts during spacewalks. The PGT is a self-contained, micro-processor controlled, battery-powered tool. It also can be used as a nonpowered ratchet wrench. The experiences of the astronauts on the first Hubble Space Telescope (HST) servicing mission led to recommendations for this smaller, more efficient tool for precision work during spacewalks. The PGT will be used on the second HST servicing mission, STS-82. Liftoff aboard Discovery is scheduled Feb. 11.

NASA Image and Video Library

1997-01-22

KENNEDY SPACE CENTER, FLA. - In KSC's Vertical Processing Facility, Louise Kleba of the Vehicle Integration Test Team (VITT) and engineer Devin Tailor of Goddard Space Flight Center examine the Pistol Grip Tool (PGT), which was designed for use by astronauts during spacewalks. The PGT is a self-contained, micro-processor controlled, battery-powered tool. It also can be used as a nonpowered ratchet wrench. The experiences of the astronauts on the first Hubble Space Telescope (HST) servicing mission led to recommendations for this smaller, more efficient tool for precision work during spacewalks. The PGT will be used on the second HST servicing mission, STS-82. Liftoff aboard Discovery is scheduled Feb. 11.

Physically coupling two objects in a bimanual task alters kinematics but not end-state comfort.

PubMed

Hughes, Charmayne M L; Haddad, Jeffrey M; Franz, Elizabeth A; Zelaznik, Howard N; Ryu, Joong Hyun

2011-06-01

People often grasp objects with an awkward grip to ensure a comfortable hand posture at the end of the movement. This end-state comfort effect is a predominant constraint during unimanual movements. However, during bimanual movements the tendency for both hands to satisfy end-state comfort is affected by factors such as end-orientation congruency and task context. Although bimanual end-state comfort has been examined when the hands manipulate two independent objects, no research has examined end-state comfort when the hands are required to manipulate two physically-coupled objects. In the present experiment, kinematics and grasp behavior during a unimanual and bimanual reaching and placing tasks were examined, when the hands manipulate two physically-connected objects. Forty-five participants were assigned to one of three groups; unimanual, bimanual no-spring (the objects were not physically connected), and bimanual spring (the objects were connected by a spring), and instructed to grasp and place objects in various end-orientations, depending on condition. Physically connecting the objects did not affect end-state comfort prevalence. However, it resulted in decreased interlimb coupling. This finding supports the notion of a flexible constraint hierarchy, in which action goals guide the selection of lower level action features (i.e., hand grip used for grasping), and the particular movements used to accomplish that goal (i.e., interlimb coupling) are controlled throughout the movement.

Cardiovascular reactivity to stressors in Indian young adults with normotensive parents.

PubMed

Verma, Anjali; Kumar, Manoj; Saxena, Indu; Kumar, Jayballabh

2013-10-01

Stress-induced increase in heart-rate and blood pressure is termed cardiovascular reactivity (CVR). Various studies are designed to monitor the CVR and use different types of experimental stressors. We have compared the CVR to three different stressors used in CVR based studies (cold pressor task, hand grip test, and video game) to identify the best suited stressor for any study design. The study was conducted on 82 (38 female) young Indian adults with normal resting basal parameters and normotensive parents. Each volunteer was subjected to three stressors: cold pressor task (CPT), hand grip test (HGT), and video game (VG). The CVR to the three stressors was compared amongst female subjects and amongst male subjects by ANOVA, and between female and male subjects by unpaired Student's t-test. Maximum CVR was obtained to HGT, while maximum gender difference in CVR was obtained in case of CPT. Heart rate and blood pressure changes obtained on playing VG were not statistically significant. When the purpose of research is to generate maximum possible CVR, we suggest the use of HGT; while if the purpose of the research is to study gender related differences, the use of CPT would be more appropriate. Unlike young adults of Western countries, VG is not perceived as a challenging task or stressor by young Indian adults and produces little change in heart rate and blood pressure.

Distrust of the senses and its association with obsessive-compulsive symptoms.

PubMed

Wong, Shiu F; Williams, Alishia D; Grisham, Jessica R

2017-12-01

Leading cognitive theories of OCD suggests that despite prevalent and persistent doubt, individuals with OCD do not have perceptual deficits. An alternate cognitive theory, the Seeking Proxies for Internal States hypothesis (SPIS), proposes that sensory distrust in OCD stems from actual deficits in accessing internal states. Consistent with the SPIS, previous research has found that high-OC individuals were less accurate than low-OC individuals in producing target levels of muscle tension in a biofeedback task and that OC symptoms were positively associated with reliance on an external proxy. The current study aimed to replicate and extend the SPIS hypothesis in two experiments using a modified version of the biofeedback-aided muscle tensing task using grip strength as the sensory input and a distance perception task. We contrasted the performance of undergraduate students self-reporting high- and low-OC symptoms. Overall, our findings failed to substantially support the SPIS hypothesis such that OC symptoms were not associated with deficient access to internal states of grip strength and distance perception or increased reliance on feedback. As this study was conducted in a non-clinical sample, we were unable to generalise our findings to a clinical population. Findings are commensurate with the wider OCD literature suggesting the absence of cognitive and perceptual deficits in OCD individuals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Delayed visual feedback affects both manual tracking and grip force control when transporting a handheld object.

PubMed

Sarlegna, Fabrice R; Baud-Bovy, Gabriel; Danion, Frédéric

2010-08-01

When we manipulate an object, grip force is adjusted in anticipation of the mechanical consequences of hand motion (i.e., load force) to prevent the object from slipping. This predictive behavior is assumed to rely on an internal representation of the object dynamic properties, which would be elaborated via visual information before the object is grasped and via somatosensory feedback once the object is grasped. Here we examined this view by investigating the effect of delayed visual feedback during dextrous object manipulation. Adult participants manually tracked a sinusoidal target by oscillating a handheld object whose current position was displayed as a cursor on a screen along with the visual target. A delay was introduced between actual object displacement and cursor motion. This delay was linearly increased (from 0 to 300 ms) and decreased within 2-min trials. As previously reported, delayed visual feedback altered performance in manual tracking. Importantly, although the physical properties of the object remained unchanged, delayed visual feedback altered the timing of grip force relative to load force by about 50 ms. Additional experiments showed that this effect was not due to task complexity nor to manual tracking. A model inspired by the behavior of mass-spring systems suggests that delayed visual feedback may have biased the representation of object dynamics. Overall, our findings support the idea that visual feedback of object motion can influence the predictive control of grip force even when the object is grasped.

Universal robotic gripper based on the jamming of granular material

PubMed Central

Brown, Eric; Rodenberg, Nicholas; Amend, John; Mozeika, Annan; Steltz, Erik; Zakin, Mitchell R.; Lipson, Hod; Jaeger, Heinrich M.

2010-01-01

Gripping and holding of objects are key tasks for robotic manipulators. The development of universal grippers able to pick up unfamiliar objects of widely varying shape and surface properties remains, however, challenging. Most current designs are based on the multifingered hand, but this approach introduces hardware and software complexities. These include large numbers of controllable joints, the need for force sensing if objects are to be handled securely without crushing them, and the computational overhead to decide how much stress each finger should apply and where. Here we demonstrate a completely different approach to a universal gripper. Individual fingers are replaced by a single mass of granular material that, when pressed onto a target object, flows around it and conforms to its shape. Upon application of a vacuum the granular material contracts and hardens quickly to pinch and hold the object without requiring sensory feedback. We find that volume changes of less than 0.5% suffice to grip objects reliably and hold them with forces exceeding many times their weight. We show that the operating principle is the ability of granular materials to transition between an unjammed, deformable state and a jammed state with solid-like rigidity. We delineate three separate mechanisms, friction, suction, and interlocking, that contribute to the gripping force. Using a simple model we relate each of them to the mechanical strength of the jammed state. This advance opens up new possibilities for the design of simple, yet highly adaptive systems that excel at fast gripping of complex objects.

Why rate when you could compare? Using the "EloChoice" package to assess pairwise comparisons of perceived physical strength.

PubMed

Clark, Andrew P; Howard, Kate L; Woods, Andy T; Penton-Voak, Ian S; Neumann, Christof

2018-01-01

We introduce "EloChoice", a package for R which uses Elo rating to assess pairwise comparisons between stimuli in order to measure perceived stimulus characteristics. To demonstrate the package and compare results from forced choice pairwise comparisons to those from more standard single stimulus rating tasks using Likert (or Likert-type) items, we investigated perceptions of physical strength from images of male bodies. The stimulus set comprised images of 82 men standing on a raised platform with minimal clothing. Strength-related anthropometrics and grip strength measurements were available for each man in the set. UK laboratory participants (Study 1) and US online participants (Study 2) viewed all images in both a Likert rating task, to collect mean Likert scores, and a pairwise comparison task, to calculate Elo, mean Elo (mElo), and Bradley-Terry scores. Within both studies, Likert, Elo and Bradley-Terry scores were closely correlated to mElo scores (all rs > 0.95), and all measures were correlated with stimulus grip strength (all rs > 0.38) and body size (all rs > 0.59). However, mElo scores were less variable than Elo scores and were hundreds of times quicker to compute than Bradley-Terry scores. Responses in pairwise comparison trials were 2/3 quicker than in Likert tasks, indicating that participants found pairwise comparisons to be easier. In addition, mElo scores generated from a data set with half the participants randomly excluded produced very comparable results to those produced with Likert scores from the full participant set, indicating that researchers require fewer participants when using pairwise comparisons.

The End-State Comfort Effect in Young Children

ERIC Educational Resources Information Center

Adalbjornsson, Carola F.; Fischman, Mark G.; Rudisill, Mary E.

2008-01-01

The end-state comfort effect has been observed in recent studies of grip selection in adults. The present study investigated whether young children also exhibit sensitivity to end-state comfort. The task was to pick up an overturned cup from a table, turn the cup right side up, and pour water into it. Two age groups (N = 20 per group) were…

Force coordination in static manipulation tasks performed using standard and non-standard grasping techniques.

PubMed

de Freitas, Paulo B; Jaric, Slobodan

2009-04-01

We evaluated coordination of the hand grip force (GF; normal component of the force acting at the hand-object contact area) and load force (LF; the tangential component) in a variety of grasping techniques and two LF directions. Thirteen participants exerted a continuous sinusoidal LF pattern against externally fixed handles applying both standard (i.e., using either the tips of the digits or the palms; the precision and palm grasps, respectively) and non-standard grasping techniques (using wrists and the dorsal finger areas; the wrist and fist grasp). We hypothesized (1) that the non-standard grasping techniques would provide deteriorated indices of force coordination when compared with the standard ones, and (2) that the nervous system would be able to adjust GF to the differences in friction coefficients of various skin areas used for grasping. However, most of the indices of force coordination remained similar across the tested grasping techniques, while the GF adjustments for the differences in friction coefficients (highest in the palm and the lowest in the fist and wrist grasp) provided inconclusive results. As hypothesized, GF relative to the skin friction was lowest in the precision grasp, but highest in the palm grasp. Therefore, we conclude that (1) the elaborate coordination of GF and LF consistently seen across the standard grasping techniques could be generalized to the non-standard ones, while (2) the ability to adjust GF using the same grasping technique to the differences in friction of various objects cannot be fully generalized to the GF adjustment when different grasps (i.e., hand segments) are used to manipulate the same object. Due to the importance of the studied phenomena for understanding both the functional and neural control aspects of manipulation, future studies should extend the current research to the transient and dynamic tasks, as well as to the general role of friction in our mechanical interactions with the environment.

A novel robotic platform for single-port abdominal surgery

NASA Astrophysics Data System (ADS)

Singh, Satwinder; Cheung, Jo L. K.; Sreedhar, Biji; Hoa, Xuyen Dai; Ng, Hoi Pang; Yeung, Chung Kwong

2018-03-01

In this paper, a novel robot-assisted platform for single-port minimally invasive surgery is presented. A miniaturized seven degrees of freedom (dof) fully internalized in-vivo actuated robotic arm is designed. Due to in-vivo actuation, the system has a smaller footprint and can generate 20 N of gripping force. The complete work envelop of the robotic arms is 252 mm × 192 mm × 322 m. With the assistance of the cannula-swivel system, the robotic arms can also be re-positioned and have multi-quadrant reachability without any additional incision. Surgical tasks, such as lifting, gripping suturing and knot tying that are commonly used in a standard surgical procedure, were performed to verify the dexterity of the robotic arms. A single-port trans-abdominal cholecystectomy in a porcine model was successfully performed to further validate its functionality.

Transient shifts in frontal and parietal circuits scale with enhanced visual feedback and changes in force variability and error

PubMed Central

Poon, Cynthia; Coombes, Stephen A.; Corcos, Daniel M.; Christou, Evangelos A.

2013-01-01

When subjects perform a learned motor task with increased visual gain, error and variability are reduced. Neuroimaging studies have identified a corresponding increase in activity in parietal cortex, premotor cortex, primary motor cortex, and extrastriate visual cortex. Much less is understood about the neural processes that underlie the immediate transition from low to high visual gain within a trial. This study used 128-channel electroencephalography to measure cortical activity during a visually guided precision grip task, in which the gain of the visual display was changed during the task. Force variability during the transition from low to high visual gain was characterized by an inverted U-shape, whereas force error decreased from low to high gain. Source analysis identified cortical activity in the same structures previously identified using functional magnetic resonance imaging. Source analysis also identified a time-varying shift in the strongest source activity. Superior regions of the motor and parietal cortex had stronger source activity from 300 to 600 ms after the transition, whereas inferior regions of the extrastriate visual cortex had stronger source activity from 500 to 700 ms after the transition. Force variability and electrical activity were linearly related, with a positive relation in the parietal cortex and a negative relation in the frontal cortex. Force error was nonlinearly related to electrical activity in the parietal cortex and frontal cortex by a quadratic function. This is the first evidence that force variability and force error are systematically related to a time-varying shift in cortical activity in frontal and parietal cortex in response to enhanced visual gain. PMID:23365186

Tensile testing grips ensure uniform loading of bimetal tubing specimens

NASA Technical Reports Server (NTRS)

Driscol, S. D.; Hunt, V.

1968-01-01

Tensile testing grip uniformly distributes stresses to the internal and external tube of bimetal tubing specimens. The grip is comprised of a slotted external tube grip, a slotted internal tube grip, a machine bolt and nut, an internal grip expansion cone, and an external grip compression nut.

Laterality and grip strength influence hand bone micro-architecture in modern humans, an HRpQCT study.

PubMed

Reina, Nicolas; Cavaignac, Etienne; Trousdale, William H; Laffosse, Jean-Michel; Braga, José

2017-06-01

It is widely hypothesized that mechanical loading, specifically repetitive low-intensity tasks, influences the inner structure of cancellous bone. As such, there is likely a relationship between handedness and bone morphology. The aim of this study is to determine patterns in trabecular bone between dominant and non-dominant hands in modern humans. Seventeen healthy patients between 22 and 32 years old were included in the study. Radial carpal bones (lunate, capitate, scaphoid, trapezium, trapezoid, 1st, 2nd and 3rd metacarpals) were analyzed with high-resolution micro-computed tomography. Additionally, crush and pinch grip were recorded. Factorial analysis indicated that bone volume ratio, trabeculae number (Tb.N), bone surface to volume ratio (BS.BV), body weight, stature and crush grip were all positively correlated with principal components 1 and 2 explaining 78.7% of the variance. Volumetric and trabecular endostructural parameters (BV/TV, BS/BV or Tb.Th, Tb.N) explain the observed inter-individual variability better than anthropometric or clinical parameters. Factors analysis regressions showed correlations between these parameters and the dominant side for crush strength for the lunate (r 2 = 0.640, P < 0.0001), trapezium (r 2 = 0.836, P < 0.0001) and third metacarpal (r 2 = 0.763). However, despite a significant lateralization in grip strength for all patients, the endostructural variability between dominant and non-dominant sides was limited in perspective to inter-individual differences. In conclusion, handedness is unlikely to generate trabecular patterns of asymmetry. It appears, however, that crush strength can be considered for endostructural analysis in the modern human wrist. © 2017 Anatomical Society.

Exploring physical exposures and identifying high-risk work tasks within the floor layer trade

PubMed Central

McGaha, Jamie; Miller, Kim; Descatha, Alexis; Welch, Laurie; Buchholz, Bryan; Evanoff, Bradley; Dale, Ann Marie

2014-01-01

Introduction Floor layers have high rates of musculoskeletal disorders yet few studies have examined their work exposures. This study used observational methods to describe physical exposures within floor laying tasks. Methods We analyzed 45 videos from 32 floor layers using Multimedia-Video Task Analysis software to determine the time in task, forces, postures, and repetitive hand movements for installation of four common flooring materials. We used the WISHA checklists to define exposure thresholds. Results Most workers (91%) met the caution threshold for one or more exposures. Workers showed high exposures in multiple body parts with variability in exposures across tasks and for different materials. Prolonged exposures were seen for kneeling, poor neck and low back postures, and intermittent but frequent hand grip forces. Conclusions Floor layers experience prolonged awkward postures and high force physical exposures in multiple body parts, which probably contribute to their high rates of musculoskeletal disorders. PMID:24274895

Bi-stem gripping apparatus

NASA Technical Reports Server (NTRS)

Sanders, Fred G. (Inventor)

1988-01-01

This invention relates to devices which grip cylindrical structures and more particularly to a device which has three arcuate gripping members having frictional surfaces for gripping and compressing a bi-stem. The bi-stem gripping apparatus is constructed having a pair of side gripping members, and an intermediate gripping member disposed between them. Sheets of a gum stock silicone rubber with frictional gripping surfaces are bonded to the inner region of the gripping members and provide frictional engagement between the bi-stem and the apparatus. A latch secures the gripping apparatus to a bi-stem, and removable handles are attached, allowing an astronaut to pull the bi-stem from its cassette. A tethering ring on the outside of the gripping apparatus provides a convenient point to which a lanyard may be attached.

Proto-Flight Manipulator Arm (P-FMA)

NASA Technical Reports Server (NTRS)

Britton, W. R.

1977-01-01

The technical development of the Proto-Flight Manipulator Arm (P-FMA) which is a seven-degree-of-freedom general-purpose arm capable of being remotely operated in an earth orbital environment is discussed. The P-FMA is a unique manipulator, combining the capabilities of significant dexterity, high tip forces, precise motion control, gear backdriveability, high end effector grip forces and torques, and the quality of flightworthiness. The 2.4-meter (8-foot) arm weighs 52.2 kilograms (115 pounds).

Effects of material properties and object orientation on precision grip kinematics.

PubMed

Paulun, Vivian C; Gegenfurtner, Karl R; Goodale, Melvyn A; Fleming, Roland W

2016-08-01

Successfully picking up and handling objects requires taking into account their physical properties (e.g., material) and position relative to the body. Such features are often inferred by sight, but it remains unclear to what extent observers vary their actions depending on the perceived properties. To investigate this, we asked participants to grasp, lift and carry cylinders to a goal location with a precision grip. The cylinders were made of four different materials (Styrofoam, wood, brass and an additional brass cylinder covered with Vaseline) and were presented at six different orientations with respect to the participant (0°, 30°, 60°, 90°, 120°, 150°). Analysis of their grasping kinematics revealed differences in timing and spatial modulation at all stages of the movement that depended on both material and orientation. Object orientation affected the spatial configuration of index finger and thumb during the grasp, but also the timing of handling and transport duration. Material affected the choice of local grasp points and the duration of the movement from the first visual input until release of the object. We find that conditions that make grasping more difficult (orientation with the base pointing toward the participant, high weight and low surface friction) lead to longer durations of individual movement segments and a more careful placement of the fingers on the object.

The Impact of the Swedish Massage on the Kinesthetic Differentiation in Healthy Individuals

PubMed Central

Mustafa, Kamil; Furmanek, Mariusz Pawel; Knapik, Aleksandra; Bacik, Bogdan; Juras, Grzegorz

2015-01-01

Background: Swedish massage is one of the common treatments to provide optimal start and readiness of athletes. The ability of kinesthetic differentiation (KD) is crucial in sport performance. This skill allows to adapt demanded muscle forces to optimize the motor tasks, and it is responsible for the precision. In the literature, there is no evidence how Swedish massage influences the kinesthetic differentiation. Purpose: The objective of the study was to evaluate the impact of Swedish massage on the kinesthetic differentiation and muscle strength of hand grip. Methods: Thirty participants took part in this investigation (17 women and 13 men). The assessment consisted of KD tests conducted on the dominant (DH) and nondominant hand (NDH) after 15 minutes of hand and forearm Swedish massage. The procedure consisted of 13 trials for each extremity. The first three were done for 100% of the participants’ capabilities (Fmax), the next five trials were done using 50% of maximum force (50% of Fmax), and in the last five trials, the participants tried to use only 50% of their previous force (1/2 of 50%). Finally, the absolute force production error (FPE) was calculated for 50% (FPE_50%) and 25% (FPE_25%). Results: The two-way repeated measure analysis of variance ANOVA did not reveal any statistically significant changes in maximal strength grip and KD between pre- and postmassage intervention in both DH and NDH hand. Correlations showed strong relationship between pre- and postmassage for maximum force (r = 0.92, p = .01 for DH, and r = 0.94, p = .01 for NDH), and only for the FPE_50% (r = 0.67, p = .01 for DH, and r = 0.71, p = .01 for NDH). Conclusions: The results obtained indicated that the application of the Swedish massage did not affect the kinesthetic differentiation in this particular young adult group. PMID:25780470

Why rate when you could compare? Using the “EloChoice” package to assess pairwise comparisons of perceived physical strength

PubMed Central

Howard, Kate L.; Woods, Andy T.; Penton-Voak, Ian S.; Neumann, Christof

2018-01-01

We introduce “EloChoice”, a package for R which uses Elo rating to assess pairwise comparisons between stimuli in order to measure perceived stimulus characteristics. To demonstrate the package and compare results from forced choice pairwise comparisons to those from more standard single stimulus rating tasks using Likert (or Likert-type) items, we investigated perceptions of physical strength from images of male bodies. The stimulus set comprised images of 82 men standing on a raised platform with minimal clothing. Strength-related anthropometrics and grip strength measurements were available for each man in the set. UK laboratory participants (Study 1) and US online participants (Study 2) viewed all images in both a Likert rating task, to collect mean Likert scores, and a pairwise comparison task, to calculate Elo, mean Elo (mElo), and Bradley-Terry scores. Within both studies, Likert, Elo and Bradley-Terry scores were closely correlated to mElo scores (all rs > 0.95), and all measures were correlated with stimulus grip strength (all rs > 0.38) and body size (all rs > 0.59). However, mElo scores were less variable than Elo scores and were hundreds of times quicker to compute than Bradley-Terry scores. Responses in pairwise comparison trials were 2/3 quicker than in Likert tasks, indicating that participants found pairwise comparisons to be easier. In addition, mElo scores generated from a data set with half the participants randomly excluded produced very comparable results to those produced with Likert scores from the full participant set, indicating that researchers require fewer participants when using pairwise comparisons. PMID:29293615

Intraindividual variability in physical and emotional functioning: comparison of adults with traumatic brain injuries and healthy adults.

PubMed

Burton, Catherine L; Hultsch, David F; Strauss, Esther; Hunter, Michael A

2002-08-01

Recent research has shown that individuals with certain neurological conditions demonstrate greater intraindividual variability on cognitive tasks compared to healthy controls. The present study investigated intraindividual variability in the domains of physical functioning and affect/stress in three groups: adults with mild head injuries, adults with moderate/severe head injuries, and healthy adults. Participants were assessed on 10 occasions and results indicated that (a) individuals with head injuries demonstrated greater variability in dominant finger dexterity and right grip strength than the healthy controls; (b) increased variability tended to be associated with poorer performance/report both within and across tasks; and (c) increased variability on one task was associated with increased variability on other tasks. The findings suggest that increased variability in physical function, as well as cognitive function, represents an indicator of neurological compromise.

Testing the efficacy of existing force-endurance models to account for the prevalence of obesity in the workforce.

PubMed

Pajoutan, Mojdeh; Cavuoto, Lora A; Mehta, Ranjana K

2017-10-01

This study evaluates whether the existing force-endurance relationship models are predictive of endurance time for overweight and obese individuals, and if not, provide revised models that can be applied for ergonomics practice. Data was collected from 141 participants (49 normal weight, 50 overweight, 42 obese) who each performed isometric endurance tasks of hand grip, shoulder flexion, and trunk extension at four levels of relative workload. Subject-specific fatigue rates and a general model of the force-endurance relationship were determined and compared to two fatigue models from the literature. There was a lack of fit between previous models and the current data for the grip (ICC = 0.8), with a shift toward lower endurance times for the new data. Application of the revised models can facilitate improved workplace design and job evaluation to accommodate the capacities of the current workforce.

Easy-To-Use Connector-Assembly Tool

NASA Technical Reports Server (NTRS)

Redmon, John W., Jr.; Jankowski, Fred

1988-01-01

Tool compensates for user's loss of dexterity under awkward conditions. Has jaws that swivel over 180 degree so angle adjusts with respect to handles. Oriented and held in position most comfortable and effective for user in given situation. Jaws lined with rubber pads so they conform to irregularly shaped parts and grips firmly but gently. Once tool engages part, it locks on it so user can release handles without losing part. Ratchet mechanism in tool allows user to work handles back and forth in confined space to connect or disconnect part. Quickly positioned, locked, and released. Gives user feel of its grip on part. Frees grasping muscles from work during part of task, giving user greater freedom to move hand. Operates with only one hand, leaving user's other hand free to manipulate wiring or other parts. Also adapts to handling and positioning extremely-hot or extremely-cold fluid lines, contaminated objects, abrasive or sharp objects, fragile items, and soft objects.

Reference Values of Grip Strength, Prevalence of Low Grip Strength, and Factors Affecting Grip Strength Values in Chinese Adults.

PubMed

Yu, Ruby; Ong, Sherlin; Cheung, Osbert; Leung, Jason; Woo, Jean

2017-06-01

The objectives of this study were to update the reference values of grip strength, to estimate the prevalence of low grip strength, and to examine the impact of different aspects of measurement protocol on grip strength values in Chinese adults. A cross-sectional survey of Chinese men (n = 714) and women (n = 4014) aged 18-102 years was undertaken in different community settings in Hong Kong. Grip strength was measured with a digital dynamometer (TKK 5401 Grip-D; Takei, Niigata, Japan). Low grip strength was defined as grip strength 2 standard deviations or more below the mean for young adults. The effects of measurement protocol on grip strength values were examined in a subsample of 45 men and women with repeated measures of grip strength taken with a hydraulic dynamometer (Baseline; Fabrication Enterprises Inc, Irvington, NY), using pair t-tests, intraclass correlation coefficient, and Bland and Altman plots. Grip strength was greater among men than among women (P < .001) and the rate of decline differed between sexes (P < .001). The prevalence of low grip strength also increased with age, reaching a rate of 16.5% in men and 20.6% in women aged 65+. Although the TKK digital dynamometer gave higher grip strength values than the Baseline hydraulic dynamometer (P < .001), the degree of agreement between the 2 dynamometers was satisfactory. Higher grip strength values were also observed when the measurement was performed with the elbow extended in a standing position, compared with that with the elbow flexed at 90° in a sitting position, using the same dynamometer (P < .05). This study updated the reference values of grip strength and estimated the prevalence of low grip strength among Chinese adults spanning a wide age range. These findings might be useful for risk estimation and evaluation of interventions. However, grip strength measurements should be interpreted with caution, as grip strength values can be affected by type of dynamometer used, assessment posture, and elbow position. Copyright © 2017 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.

Variability of Grip Kinetics during Adult Signature Writing

PubMed Central

Ghali, Bassma; Thalanki Anantha, Nayanashri; Chan, Jennifer; Chau, Tom

2013-01-01

Grip kinetics and their variation are emerging as important considerations in the clinical assessment of handwriting pathologies, fine motor rehabilitation, biometrics, forensics and ergonomic pen design. This study evaluated the intra- and inter-participant variability of grip shape kinetics in adults during signature writing. Twenty (20) adult participants wrote on a digitizing tablet using an instrumented pen that measured the forces exerted on its barrel. Signature samples were collected over 10 days, 3 times a day, to capture temporal variations in grip shape kinetics. A kinetic topography (i.e., grip shape image) was derived per signature by time-averaging the measured force at each of 32 locations around the pen barrel. The normalized cross correlations (NCC) of grip shape images were calculated within- and between-participants. Several classification algorithms were implemented to gauge the error rate of participant discrimination based on grip shape kinetics. Four different grip shapes emerged and several participants made grip adjustments (change in grip shape or grip height) or rotated the pen during writing. Nonetheless, intra-participant variation in grip kinetics was generally much smaller than inter-participant force variations. Using the entire grip shape images as a 32-dimensional input feature vector, a K-nearest neighbor classifier achieved an error rate of % in discriminating among participants. These results indicate that writers had unique grip shape kinetics that were repeatable over time but distinct from those of other participants. The topographic analysis of grip kinetics may inform the development of personalized interventions or customizable grips in clinical and industrial applications, respectively. PMID:23658812

Variability of grip kinetics during adult signature writing.

PubMed

Ghali, Bassma; Thalanki Anantha, Nayanashri; Chan, Jennifer; Chau, Tom

2013-01-01

Grip kinetics and their variation are emerging as important considerations in the clinical assessment of handwriting pathologies, fine motor rehabilitation, biometrics, forensics and ergonomic pen design. This study evaluated the intra- and inter-participant variability of grip shape kinetics in adults during signature writing. Twenty (20) adult participants wrote on a digitizing tablet using an instrumented pen that measured the forces exerted on its barrel. Signature samples were collected over 10 days, 3 times a day, to capture temporal variations in grip shape kinetics. A kinetic topography (i.e., grip shape image) was derived per signature by time-averaging the measured force at each of 32 locations around the pen barrel. The normalized cross correlations (NCC) of grip shape images were calculated within- and between-participants. Several classification algorithms were implemented to gauge the error rate of participant discrimination based on grip shape kinetics. Four different grip shapes emerged and several participants made grip adjustments (change in grip shape or grip height) or rotated the pen during writing. Nonetheless, intra-participant variation in grip kinetics was generally much smaller than inter-participant force variations. Using the entire grip shape images as a 32-dimensional input feature vector, a K-nearest neighbor classifier achieved an error rate of 1.2±0.4% in discriminating among participants. These results indicate that writers had unique grip shape kinetics that were repeatable over time but distinct from those of other participants. The topographic analysis of grip kinetics may inform the development of personalized interventions or customizable grips in clinical and industrial applications, respectively.

The interaction of force and repetition on musculoskeletal and neural tissue responses and sensorimotor behavior in a rat model of work-related musculoskeletal disorders

PubMed Central

2013-01-01

Background We examined the relationship of musculoskeletal risk factors underlying force and repetition on tissue responses in an operant rat model of repetitive reaching and pulling, and if force x repetition interactions were present, indicative of a fatigue failure process. We examined exposure-dependent changes in biochemical, morphological and sensorimotor responses occurring with repeated performance of a handle-pulling task for 12 weeks at one of four repetition and force levels: 1) low repetition with low force, 2) high repetition with low force, 3) low repetition with high force, and 4) high repetition with high force (HRHF). Methods Rats underwent initial training for 4–6 weeks, and then performed one of the tasks for 12 weeks, 2 hours/day, 3 days/week. Reflexive grip strength and sensitivity to touch were assayed as functional outcomes. Flexor digitorum muscles and tendons, forelimb bones, and serum were assayed using ELISA for indicators of inflammation, tissue stress and repair, and bone turnover. Histomorphometry was used to assay macrophage infiltration of tissues, spinal cord substance P changes, and tissue adaptative or degradative changes. MicroCT was used to assay bones for changes in bone quality. Results Several force x repetition interactions were observed for: muscle IL-1alpha and bone IL-1beta; serum TNFalpha, IL-1alpha, and IL-1beta; muscle HSP72, a tissue stress and repair protein; histomorphological evidence of tendon and cartilage degradation; serum biomarkers of bone degradation (CTXI) and bone formation (osteocalcin); and morphological evidence of bone adaptation versus resorption. In most cases, performance of the HRHF task induced the greatest tissue degenerative changes, while performance of moderate level tasks induced bone adaptation and a suggestion of muscle adaptation. Both high force tasks induced median nerve macrophage infiltration, spinal cord sensitization (increased substance P), grip strength declines and forepaw mechanical allodynia by task week 12. Conclusions Although not consistent in all tissues, we found several significant interactions between the critical musculoskeletal risk factors of force and repetition, consistent with a fatigue failure process in musculoskeletal tissues. Prolonged performance of HRHF tasks exhibited significantly increased risk for musculoskeletal disorders, while performance of moderate level tasks exhibited adaptation to task demands. PMID:24156755

The interaction of force and repetition on musculoskeletal and neural tissue responses and sensorimotor behavior in a rat model of work-related musculoskeletal disorders.

PubMed

Barbe, Mary F; Gallagher, Sean; Massicotte, Vicky S; Tytell, Michael; Popoff, Steven N; Barr-Gillespie, Ann E

2013-10-25

We examined the relationship of musculoskeletal risk factors underlying force and repetition on tissue responses in an operant rat model of repetitive reaching and pulling, and if force x repetition interactions were present, indicative of a fatigue failure process. We examined exposure-dependent changes in biochemical, morphological and sensorimotor responses occurring with repeated performance of a handle-pulling task for 12 weeks at one of four repetition and force levels: 1) low repetition with low force, 2) high repetition with low force, 3) low repetition with high force, and 4) high repetition with high force (HRHF). Rats underwent initial training for 4-6 weeks, and then performed one of the tasks for 12 weeks, 2 hours/day, 3 days/week. Reflexive grip strength and sensitivity to touch were assayed as functional outcomes. Flexor digitorum muscles and tendons, forelimb bones, and serum were assayed using ELISA for indicators of inflammation, tissue stress and repair, and bone turnover. Histomorphometry was used to assay macrophage infiltration of tissues, spinal cord substance P changes, and tissue adaptative or degradative changes. MicroCT was used to assay bones for changes in bone quality. Several force x repetition interactions were observed for: muscle IL-1alpha and bone IL-1beta; serum TNFalpha, IL-1alpha, and IL-1beta; muscle HSP72, a tissue stress and repair protein; histomorphological evidence of tendon and cartilage degradation; serum biomarkers of bone degradation (CTXI) and bone formation (osteocalcin); and morphological evidence of bone adaptation versus resorption. In most cases, performance of the HRHF task induced the greatest tissue degenerative changes, while performance of moderate level tasks induced bone adaptation and a suggestion of muscle adaptation. Both high force tasks induced median nerve macrophage infiltration, spinal cord sensitization (increased substance P), grip strength declines and forepaw mechanical allodynia by task week 12. Although not consistent in all tissues, we found several significant interactions between the critical musculoskeletal risk factors of force and repetition, consistent with a fatigue failure process in musculoskeletal tissues. Prolonged performance of HRHF tasks exhibited significantly increased risk for musculoskeletal disorders, while performance of moderate level tasks exhibited adaptation to task demands.

Handle grip span for optimising finger-specific force capability as a function of hand size.

PubMed

Lee, Soo-Jin; Kong, Yong-Ku; Lowe, Brian D; Song, Seongho

2009-05-01

Five grip spans (45 to 65 mm) were tested to evaluate the effects of handle grip span and user's hand size on maximum grip strength, individual finger force and subjective ratings of comfort using a computerised digital dynamometer with independent finger force sensors. Forty-six males participated and were assigned into three hand size groups (small, medium, large) according to their hands' length. In general, results showed the 55- and 50-mm grip spans were rated as the most comfortable sizes and showed the largest grip strength (433.6 N and 430.8 N, respectively), whereas the 65-mm grip span handle was rated as the least comfortable size and the least grip strength. With regard to the interaction effect of grip span and hand size, small and medium-hand participants rated the best preference for the 50- to 55-mm grip spans and the least for the 65-mm grip span, whereas large-hand participants rated the 55- to 60-mm grip spans as the most preferred and the 45-mm grip span as the least preferred. Normalised grip span (NGS) ratios (29% and 27%) are the ratios of user's hand length to handle grip span. The NGS ratios were obtained and applied for suggesting handle grip spans in order to maximise subjective comfort as well as gripping force according to the users' hand sizes. In the analysis of individual finger force, the middle finger force showed the highest contribution (37.5%) to the total finger force, followed by the ring (28.7%), index (20.2%) and little (13.6%) finger. In addition, each finger was observed to have a different optimal grip span for exerting the maximum force, resulting in a bow-contoured shaped handle (the grip span of the handle at the centre is larger than the handle at the end) for two-handle hand tools. Thus, the grip spans for two-handle hand tools may be designed according to the users' hand/finger anthropometrics to maximise subjective ratings and performance based on this study. Results obtained in this study will provide guidelines for hand tool designers and manufacturers for designing grip spans of two-handle tools, which can maximise handle comfort and performance.

Effect of visual feedback on brain activation during motor tasks: an FMRI study.

PubMed

Noble, Jeremy W; Eng, Janice J; Boyd, Lara A

2013-07-01

This study examined the effect of visual feedback and force level on the neural mechanisms responsible for the performance of a motor task. We used a voxel-wise fMRI approach to determine the effect of visual feedback (with and without) during a grip force task at 35% and 70% of maximum voluntary contraction. Two areas (contralateral rostral premotor cortex and putamen) displayed an interaction between force and feedback conditions. When the main effect of feedback condition was analyzed, higher activation when visual feedback was available was found in 22 of the 24 active brain areas, while the two other regions (contralateral lingual gyrus and ipsilateral precuneus) showed greater levels of activity when no visual feedback was available. The results suggest that there is a potentially confounding influence of visual feedback on brain activation during a motor task, and for some regions, this is dependent on the level of force applied.

An instrumented object for hand exercise and assessment using a pneumatic pressure sensor

NASA Astrophysics Data System (ADS)

Mohan, A.; Tharion, G.; Kumar, R. K.; Devasahayam, S. R.

2018-05-01

Measurement of grip force is important for both exercise training and assessment of the hand during physical rehabilitation. The standard method uses a grip dynamometer which measures the force between the fingers and opposing thumb. The primary limitation of the grip dynamometer is the restriction of measurement to cylindrical grasps. Any deformation of the hand due to muscular or skeletal disease makes the grip dynamometer difficult or impossible to use. An alternative to the grip dynamometer is a sealed pneumatic object that can be gripped by the hand. Measurement of the internal pressure in the object can be related to the grip force. In this paper, we analyze such a pneumatic pressure sensing object for hand grip assessment and also describe an easy fabrication of the grip sensor. The instrumented object presented in this paper is designed to assess both the maximal voluntary grip forces and continuous grip force to monitor control of hand function during exercise under instruction from a therapist. Potential uses of such a pneumatic pressure sensing object for hand grip are in physical rehabilitation of patients following paralysing illnesses like stroke and spinal cord injury.

Pistol-grip Syringe holder (Cameco syringe pistol) in fine needle aspiration Biopsy: any advantages over the use of direct finger grip?

PubMed

Mayun, A A; Nggada, H A; Abdulazzez, J O; Musa, A B; Pindiga, U H; Khalil, M I

2013-06-01

The study seeks to determine the advantages of using the pistol-grip syringe holder in the performance of FNAB over the use of direct finger grip method. The skin is cleaned with gauze soaked in methylated spirit and the lump is located and firmly held between the thumb and fore finger of the free hand. The syringe is held by the out side of the barrel or by pistol-grip, and the needle tip pushed into the lesion. The plunger is partially retracted, creating a negative pressure. The cutting edge of the needle tip frees the cells inside the lesion which are sucked into the fine bore of the needle. The contents of the needle are then emptied on a microscopic slide and thinly smeared. The slides are then fixed in alcohol and later stained. These were examined under the microscope and a comparison between the aspirations using pistol-grip and direct finger grip was made. A total of 266 cases of FNABs were carried out from 1st January to 31st December, 2008. There were 89 breast cases out of which 42 (47%) had pistol-grip method and 47 (53%) had direct finger grip method; 74 thyroid cases out of which 28 (38%) were pistol-grip and 46 (62%) were direct finger grip cases; 56 cases of lymph node FNABs of which 18(32%) and 38 (68%) had pistol-grip and direct finger grip methods respectively. There were 23 cases of salivary gland FNABs having 8 (35%) and 15 (65%) as pistol-grip and direct finger grip methods respectively. Marked cellularity was observed in the majority of cases using both methods of FNABs. This study has shown that the use of pistol-grip syringe holder in the performance of FNABs has no significant advantage compared to the direct finger grip method.

Influence of dual task and frailty on gait parameters of older community-dwelling individuals

PubMed Central

Guedes, Rita C.; Dias, Rosângela C.; Pereira, Leani S. M.; Silva, Sílvia L. A.; Lustosa, Lygia P.; Dias, João M. D.

2014-01-01

Background: Gait parameters such as gait speed (GS) are important indicators of functional capacity. Frailty Syndrome is closely related to GS and is also capable of predicting adverse outcomes. The cognitive demand of gait control is usually explored with dual-task (DT) methodology. Objective: To investigate the effect of DT and frailty on the spatio-temporal parameters of gait in older people and identify which variables relate to GS. Method: The presence of frailty was verified by Fried's Frailty Criteria. Cognitive function was evaluated with the Mini-Mental State Exam (MMSE) and gait parameters were analyzed through the GAITRite(r) system in the single-task and DT conditions. The Kolmogorov-Smirnov, ANOVA, and Pearson's Correlation tests were administered. Results: The participants were assigned to the groups frail (FG), pre-frail (PFG), and non-frail (NFG). During the DT, the three groups showed a decrease in GS, cadence, and stride length and an increase in stride time (p<0.001). The reduction in the GS of the FG during the DT showed a positive correlation with the MMSE scores (r=730; p=0.001) and with grip strength (r=681; p=0.001). Conclusions: Gait parameters are more affected by the DT, especially in the frail older subjects. The reduction in GS in the FG is associated with lower grip strength and lower scores in the MMSE. The GS was able to discriminate the older adults in the three levels of frailty, being an important measure of the functional capacity in this population. PMID:25372007

Comparative investigations of manual action representations: evidence that chimpanzees represent the costs of potential future actions involving tools.

PubMed

Frey, Scott H; Povinelli, Daniel J

2012-01-12

The ability to adjust one's ongoing actions in the anticipation of forthcoming task demands is considered as strong evidence for the existence of internal action representations. Studies of action selection in tool use reveal that the behaviours that we choose in the present moment differ depending on what we intend to do next. Further, they point to a specialized role for mechanisms within the human cerebellum and dominant left cerebral hemisphere in representing the likely sensory costs of intended future actions. Recently, the question of whether similar mechanisms exist in other primates has received growing, but still limited, attention. Here, we present data that bear on this issue from a species that is a natural user of tools, our nearest living relative, the chimpanzee. In experiment 1, a subset of chimpanzees showed a non-significant tendency for their grip preferences to be affected by anticipation of the demands associated with bringing a tool's baited end to their mouths. In experiment 2, chimpanzees' initial grip preferences were consistently affected by anticipation of the forthcoming movements in a task that involves using a tool to extract a food reward. The partial discrepancy between the results of these two studies is attributed to the ability to accurately represent differences between the motor costs associated with executing the two response alternatives available within each task. These findings suggest that chimpanzees are capable of accurately representing the costs of intended future actions, and using those predictions to select movements in the present even in the context of externally directed tool use.

Comparative investigations of manual action representations: evidence that chimpanzees represent the costs of potential future actions involving tools

PubMed Central

Frey, Scott H.; Povinelli, Daniel J.

2012-01-01

The ability to adjust one's ongoing actions in the anticipation of forthcoming task demands is considered as strong evidence for the existence of internal action representations. Studies of action selection in tool use reveal that the behaviours that we choose in the present moment differ depending on what we intend to do next. Further, they point to a specialized role for mechanisms within the human cerebellum and dominant left cerebral hemisphere in representing the likely sensory costs of intended future actions. Recently, the question of whether similar mechanisms exist in other primates has received growing, but still limited, attention. Here, we present data that bear on this issue from a species that is a natural user of tools, our nearest living relative, the chimpanzee. In experiment 1, a subset of chimpanzees showed a non-significant tendency for their grip preferences to be affected by anticipation of the demands associated with bringing a tool's baited end to their mouths. In experiment 2, chimpanzees' initial grip preferences were consistently affected by anticipation of the forthcoming movements in a task that involves using a tool to extract a food reward. The partial discrepancy between the results of these two studies is attributed to the ability to accurately represent differences between the motor costs associated with executing the two response alternatives available within each task. These findings suggest that chimpanzees are capable of accurately representing the costs of intended future actions, and using those predictions to select movements in the present even in the context of externally directed tool use. PMID:22106426

The effects of instruction and hand dominance on grip-to-load force coordination in manipulation tasks.

PubMed

Jin, Xin; Uygur, Mehmet; Getchell, Nancy; Hall, Susan J; Jaric, Slobodan

2011-10-31

The force applied upon a vertically oriented hand-held object could be decomposed into two orthogonal and highly coordinated components: the grip force (GF; the component perpendicular to the hand-object contact area that provides friction) and the load force (LF; the parallel component that can move the object or support the body). The aim of this study was to investigate the underexplored effects of task instruction and hand dominance on GF-LF coordination. Sixteen right-handed subjects performed bimanual manipulation against a horizontally oriented instrumented device under different sets of instructions. The tasks involved exertion of ramp-and-hold or oscillation patterns of LF performed symmetrically with two hands, while the instructions regarding individual actions were either similar (pull with both hands) or dissimilar (pull with one hand and hold with another). The results revealed that the instruction "to pull" leads to higher indices of GF-LF coordination than the instruction "to hold", as evidenced by a lower GF-LF ratio, higher GF-LF coupling, and higher GF modulation. The only effect of hand dominance was a moderate time lag of GF relative to LF changes observed in the non-dominant hand. We conclude that the instructions could play an important role in GF-LF coordination and, therefore, they should be taken into account when exploring or routinely testing hand function. Additionally, the results suggest that the neural control of GF of the non-dominant hand could involve some feedback mechanisms. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Complex motor task associated with non-linear BOLD responses in cerebro-cortical areas and cerebellum.

PubMed

Alahmadi, Adnan A S; Samson, Rebecca S; Gasston, David; Pardini, Matteo; Friston, Karl J; D'Angelo, Egidio; Toosy, Ahmed T; Wheeler-Kingshott, Claudia A M

2016-06-01

Previous studies have used fMRI to address the relationship between grip force (GF) applied to an object and BOLD response. However, whilst the majority of these studies showed a linear relationship between GF and neural activity in the contralateral M1 and ipsilateral cerebellum, animal studies have suggested the presence of non-linear components in the GF-neural activity relationship. Here, we present a methodology for assessing non-linearities in the BOLD response to different GF levels, within primary motor as well as sensory and cognitive areas and the cerebellum. To be sensitive to complex forms, we designed a feasible grip task with five GF targets using an event-related visually guided paradigm and studied a cohort of 13 healthy volunteers. Polynomial functions of increasing order were fitted to the data. (1) activated motor areas irrespective of GF; (2) positive higher-order responses in and outside M1, involving premotor, sensory and visual areas and cerebellum; (3) negative correlations with GF, predominantly involving the visual domain. Overall, our results suggest that there are physiologically consistent behaviour patterns in cerebral and cerebellar cortices; for example, we observed the presence of a second-order effect in sensorimotor areas, consistent with an optimum metabolic response at intermediate GF levels, while higher-order behaviour was found in associative and cognitive areas. At higher GF levels, sensory-related cortical areas showed reduced activation, interpretable as a redistribution of the neural activity for more demanding tasks. These results have the potential of opening new avenues for investigating pathological mechanisms of neurological diseases.

Influence of Inter-Training Intervals on Intermanual Transfer Effects in Upper-Limb Prosthesis Training: A Randomized Pre-Posttest Study.

PubMed

Romkema, Sietske; Bongers, Raoul M; van der Sluis, Corry K

2015-01-01

Improvement in prosthetic training using intermanual transfer (the transfer of motor skills from the trained, “unaffected” hand to the untrained, “affected” hand) has been shown in previous studies. The aim of this study is to determine the influence of the inter-training interval on the magnitude of the intermanual transfer effects. This was done using a mechanistic, randomized, single-blinded pretest-posttest design. Sixty-four able-bodied, right-handed participants were randomly assigned to the Short and Long Interval Training Groups and the Short and Long Interval Control Groups. The Short and Long Interval Training Groups used a prosthesis simulator in their training program. The Short and Long Interval Control Groups executed a sham training program, that is, a dummy training program in which the same muscles were trained as with the prosthesis simulator. The Short Interval Training Group and the Short Interval Control Groups trained on consecutive days, while the Long Interval Training Group and Long Interval Control Group trained twice a week. To determine the improvement in skills, a test was administered before, immediately after, and at two points in time after the training. Training was performed with the “unaffected” arm; tests were performed with the “affected” arm. The outcome measurements were: the movement time (the time from the beginning of the movement until completion of the task); the duration of maximum hand opening, (the opening of the prosthetic hand while grasping an object); and the grip-force control (the error from the required grip-force during a tracking task). Intermanual transfer was found in movement times, but not in hand opening or grip-force control. The length of the inter-training interval did not affect the magnitude of intermanual transfer effects. No difference in the intermanual transfer effect in upper-limb prosthesis training was found for training on a daily basis as compared to training twice a week. Nederlands Trial Register NTR3888.

Influence of Inter-Training Intervals on Intermanual Transfer Effects in Upper-Limb Prosthesis Training: A Randomized Pre-Posttest Study

PubMed Central

Romkema, Sietske; Bongers, Raoul M.; van der Sluis, Corry K.

2015-01-01

Improvement in prosthetic training using intermanual transfer (the transfer of motor skills from the trained, “unaffected” hand to the untrained, “affected” hand) has been shown in previous studies. The aim of this study is to determine the influence of the inter-training interval on the magnitude of the intermanual transfer effects. This was done using a mechanistic, randomized, single-blinded pretest-posttest design. Sixty-four able-bodied, right-handed participants were randomly assigned to the Short and Long Interval Training Groups and the Short and Long Interval Control Groups. The Short and Long Interval Training Groups used a prosthesis simulator in their training program. The Short and Long Interval Control Groups executed a sham training program, that is, a dummy training program in which the same muscles were trained as with the prosthesis simulator. The Short Interval Training Group and the Short Interval Control Groups trained on consecutive days, while the Long Interval Training Group and Long Interval Control Group trained twice a week. To determine the improvement in skills, a test was administered before, immediately after, and at two points in time after the training. Training was performed with the “unaffected” arm; tests were performed with the “affected” arm. The outcome measurements were: the movement time (the time from the beginning of the movement until completion of the task); the duration of maximum hand opening, (the opening of the prosthetic hand while grasping an object); and the grip-force control (the error from the required grip-force during a tracking task). Intermanual transfer was found in movement times, but not in hand opening or grip-force control. The length of the inter-training interval did not affect the magnitude of intermanual transfer effects. No difference in the intermanual transfer effect in upper-limb prosthesis training was found for training on a daily basis as compared to training twice a week. Trial Registration Nederlands Trial Register NTR3888 PMID:26075396

Motor Performance is Impaired Following Vestibular Stimulation in Ageing Mice

PubMed Central

Tung, Victoria W. K.; Burton, Thomas J.; Quail, Stephanie L.; Mathews, Miranda A.; Camp, Aaron J.

2016-01-01

Balance and maintaining postural equilibrium are important during stationary and dynamic movements to prevent falls, particularly in older adults. While our sense of balance is influenced by vestibular, proprioceptive, and visual information, this study focuses primarily on the vestibular component and its age-related effects on balance. C57Bl/6J mice of ages 1, 5–6, 8–9 and 27–28 months were tested using a combination of standard (such as grip strength and rotarod) and newly-developed behavioral tests (including balance beam and walking trajectory tests with a vestibular stimulus). In the current study, we confirm a decline in fore-limb grip strength and gross motor coordination as age increases. We also show that a vestibular stimulus of low frequency (2–3 Hz) and duration can lead to age-dependent changes in balance beam performance, which was evident by increases in latency to begin walking on the beam as well as the number of times hind-feet slip (FS) from the beam. Furthermore, aged mice (27–28 months) that received continuous access to a running wheel for 4 weeks did not improve when retested. Mice of ages 1, 10, 13 and 27–28 months were also tested for changes in walking trajectory as a result of the vestibular stimulus. While no linear relationship was observed between the changes in trajectory and age, 1-month-old mice were considerably less affected than mice of ages 10, 13 and 27–28 months. Conclusion: this study confirms there are age-related declines in grip strength and gross motor coordination. We also demonstrate age-dependent changes to finer motor abilities as a result of a low frequency and duration vestibular stimulus. These changes showed that while the ability to perform the balance beam task remained intact across all ages tested, behavioral changes in task performance were observed. PMID:26869921

Motor Performance is Impaired Following Vestibular Stimulation in Ageing Mice.

PubMed

Tung, Victoria W K; Burton, Thomas J; Quail, Stephanie L; Mathews, Miranda A; Camp, Aaron J

2016-01-01

Balance and maintaining postural equilibrium are important during stationary and dynamic movements to prevent falls, particularly in older adults. While our sense of balance is influenced by vestibular, proprioceptive, and visual information, this study focuses primarily on the vestibular component and its age-related effects on balance. C57Bl/6J mice of ages 1, 5-6, 8-9 and 27-28 months were tested using a combination of standard (such as grip strength and rotarod) and newly-developed behavioral tests (including balance beam and walking trajectory tests with a vestibular stimulus). In the current study, we confirm a decline in fore-limb grip strength and gross motor coordination as age increases. We also show that a vestibular stimulus of low frequency (2-3 Hz) and duration can lead to age-dependent changes in balance beam performance, which was evident by increases in latency to begin walking on the beam as well as the number of times hind-feet slip (FS) from the beam. Furthermore, aged mice (27-28 months) that received continuous access to a running wheel for 4 weeks did not improve when retested. Mice of ages 1, 10, 13 and 27-28 months were also tested for changes in walking trajectory as a result of the vestibular stimulus. While no linear relationship was observed between the changes in trajectory and age, 1-month-old mice were considerably less affected than mice of ages 10, 13 and 27-28 months. this study confirms there are age-related declines in grip strength and gross motor coordination. We also demonstrate age-dependent changes to finer motor abilities as a result of a low frequency and duration vestibular stimulus. These changes showed that while the ability to perform the balance beam task remained intact across all ages tested, behavioral changes in task performance were observed.

Associations of Grip Strength and Change in Grip Strength With All-Cause and Cardiovascular Mortality in a European Older Population

PubMed Central

Prasitsiriphon, Orawan; Pothisiri, Wiraporn

2018-01-01

Objective: (1) To examine the associations between 3 measures of grip strength: static grip strength, change in grip strength, and the combination of grip strength and its change, with all-cause and cardiovascular mortality, and (2) to determine which measure is the most powerful predictor of all-cause and cardiovascular mortality among the European older population. Method: Data come from the first 4 waves of the Survey of Health, Ageing and Retirement in Europe (SHARE). A Cox proportional hazard model and a competing risk regression model were used to assess the associations. To determine the best predictor, Akaike information criterion was applied. Results: Grip strength and the combination of grip strength and its change were associated with all-cause and cardiovascular mortality. Change in grip strength was correlated with only all-cause mortality. Among the 3 measures, the static measure of grip strength was the best predictor of cardiovascular mortality whereas the combined measure is that of all-cause mortality. Discussion: Grip strength is a significant indicator of all-cause and cardiovascular mortality. The combination of grip strength and its change can be used to increase the accuracy for prediction of all-cause mortality among older persons.

Complementary roles of different oscillatory activities in the subthalamic nucleus in coding motor effort in Parkinsonism.

PubMed

Tan, Huiling; Pogosyan, Alek; Anzak, Anam; Ashkan, Keyoumars; Bogdanovic, Marko; Green, Alexander L; Aziz, Tipu; Foltynie, Thomas; Limousin, Patricia; Zrinzo, Ludvic; Brown, Peter

2013-10-01

The basal ganglia may play an important role in the control of motor scaling or effort. Recently local field potential (LFP) recordings from patients with deep brain stimulation electrodes in the basal ganglia have suggested that local increases in the synchronisation of neurons in the gamma frequency band may correlate with force or effort. Whether this feature uniquely codes for effort and whether such a coding mechanism holds true over a range of efforts is unclear. Here we investigated the relationship between frequency-specific oscillatory activities in the subthalamic nucleus (STN) and manual grips made with different efforts. The latter were self-rated using the 10 level Borg scale ranging from 0 (no effort) to 10 (maximal effort). STN LFP activities were recorded in patients with Parkinson's Disease (PD) who had undergone functional surgery. Patients were studied while motor performance was improved by dopaminergic medication. In line with previous studies we observed power increase in the theta/alpha band (4-12 Hz), power suppression in the beta band (13-30 Hz) and power increase in the gamma band (55-90 Hz) and high frequency band (101-375 Hz) during voluntary grips. Beta suppression deepened, and then reached a floor level as effort increased. Conversely, gamma and high frequency power increases were enhanced during grips made with greater effort. Multiple regression models incorporating the four different spectral changes confirmed that the modulation of power in the beta band was the only independent predictor of effort during grips made with efforts rated <5. In contrast, increases in gamma band activity were the only independent predictor of effort during grips made with efforts ≥5. Accordingly, the difference between power changes in the gamma and beta bands correlated with effort across all effort levels. These findings suggest complementary roles for changes in beta and gamma band activities in the STN in motor effort coding. The latter function is thought to be impaired in untreated PD where task-related reactivity in these two bands is deficient. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Morphology and function of the forelimb in arboreal frogs: specializations for grasping ability?

PubMed Central

Manzano, Adriana S; Abdala, Virginia; Herrel, Anthony

2008-01-01

Frogs are characterized by a unique morphology associated with their saltatory lifestyle. Although variation in the form and function of the pelvic girdle and associated appendicular system related to specialized locomotor modes such as swimming or burrowing has been documented, the forelimbs have typically been viewed as relatively unspecialized. Yet, previous authors have noted versatility in forelimb function among arboreal frogs associated with feeding. Here we study the morphology and function of the forelimb and hand during locomotion in two species of arboreal frogs (Litoria caerulea and Phyllomedusa bicolor). Our data show a complex arrangement of the distal forelimb and hand musculature with some notable differences between species. Analyses of high-speed video and video fluoroscopy recordings show that forelimbs are used in alternating fashion in a diagonal sequence footfall pattern and that the position of the hand is adjusted when walking on substrates of different diameters. Electromyographic recordings show that the flexors of the hand are active during substrate contact, suggesting the use of gripping to generate a stabilizing torque. Measurements of grasping forces in vivo and during stimulation experiments show that both species, are capable of executing a so-called power grip but also indicates marked differences between species, in the magnitude of forces generated. Stimulation experiments showed an increased control of digit flexion in the more specialized of the two species, allowing it to execute a precision grip paralleled only by that seen in primates. PMID:18565111

Morphology and function of the forelimb in arboreal frogs: specializations for grasping ability?

PubMed

Manzano, Adriana S; Abdala, Virginia; Herrel, Anthony

2008-09-01

Frogs are characterized by a unique morphology associated with their saltatory lifestyle. Although variation in the form and function of the pelvic girdle and associated appendicular system related to specialized locomotor modes such as swimming or burrowing has been documented, the forelimbs have typically been viewed as relatively unspecialized. Yet, previous authors have noted versatility in forelimb function among arboreal frogs associated with feeding. Here we study the morphology and function of the forelimb and hand during locomotion in two species of arboreal frogs (Litoria caerulea and Phyllomedusa bicolor). Our data show a complex arrangement of the distal forelimb and hand musculature with some notable differences between species. Analyses of high-speed video and video fluoroscopy recordings show that forelimbs are used in alternating fashion in a diagonal sequence footfall pattern and that the position of the hand is adjusted when walking on substrates of different diameters. Electromyographic recordings show that the flexors of the hand are active during substrate contact, suggesting the use of gripping to generate a stabilizing torque. Measurements of grasping forces in vivo and during stimulation experiments show that both species, are capable of executing a so-called power grip but also indicates marked differences between species, in the magnitude of forces generated. Stimulation experiments showed an increased control of digit flexion in the more specialized of the two species, allowing it to execute a precision grip paralleled only by that seen in primates.

Fine motor skills predict performance in the Jebsen Taylor Hand Function Test after stroke.

PubMed

Allgöwer, Kathrin; Hermsdörfer, Joachim

2017-10-01

To determine factors characterizing the differences in fine motor performance between stroke patients and controls. To confirm the relevance of the factors by analyzing their predictive power with regard to the Jebsen Taylor Hand Function Test (JTHFT), a common clinical test of fine motor control. Twenty-two people with slight paresis in an early chronic phase following stroke and twenty-two healthy controls were examined. Performance on the JTHFT, Nine-Hole Peg Test and 2-point discrimination was evaluated. To analyze object manipulation skills, grip forces and temporal measures were examined during (1) lifting actions with variations of weight and surface (2) cyclic movements (3) predictive/reactive catching tasks. Three other aspects of force control included (4) visuomotor tracking (5) fast force changes and (6) grip strength. Based on 9 parameters which significantly distinguished fine motor performance in the two groups, we identified three principal components (factors): grip force scaling, motor coordination and speed of movement. The three factors are shown to predict JTHFT scores via linear regression (R 2 =0.687, p<0.001). We revealed a factor structure behind fine motor impairments following stroke and showed that it explains JTHFT results to a large extend. This result can serve as a basis for improving diagnostics and enabling more targeted therapy. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Helical grip for the cable cars of San Francisco

NASA Technical Reports Server (NTRS)

Peyran, R. J.

1979-01-01

A helical cable car grip to minimize high maintenance costs of San Francisco's cable car operation is presented. The grip establishes a rolling contact between the cable and grip to reduce sliding friction and associated cable wear. The design, development, and testing of the helical cable car grip are described.

Level II Ergonomic Analyses, Dover AFB, DE

DTIC Science & Technology

1999-02-01

1.5" (2.5-3.8 cm). X Grip design requires fingertip grip. Grip dimensions 3"x3" xl 3/4" * Grip Diameter for a fingertip grip tool should be... anthropometry , engineering, and kinesiology. The first three sciences help to define worker capabilities and limitations (e.g., how much hand strength

Wire Test Grip Fixture

NASA Technical Reports Server (NTRS)

Burke, Christopher S.

2011-01-01

Wire-testing issues, such as the gripping strains imposed on the wire, play a critical role in obtaining clean data. In a standard test frame fitted with flat wedge grips, the gripping action alone creates stresses on the wire specimen that cause the wire to fail at the grip location. A new test frame, which is outfitted with a vacuum chamber, negated the use of any conventional commercially available wire test fixtures, as only 7 in. (17.8 cm) existed between the grip faces. An innovative grip fixture was designed to test thin gauge wire for a variety of applications in an existing Instron test frame outfitted with a vacuum chamber.

Impaired anticipatory control of grasp during obstacle crossing in Parkinson's disease.

PubMed

McIsaac, Tara L; Diermayr, Gudrun; Albert, Frederic

2012-05-16

During self-paced walking, people with Parkinson's disease maintain anticipatory control during object grasping. However, common functional tasks often include carrying an object while changing step patterns mid-path and maneuvering over obstacles, increasing task complexity and attentional demands. Thus, the present study investigated the effect of Parkinson's disease on the modulation of grasping force changes as a function of gait-related inertial forces. Subjects with Parkinson's disease maintained the ability to scale and to couple over time their grip and inertial forces while walking at irregular step lengths, but were unable to maintain the temporal coupling of grasping forces compared to controls during obstacle crossing. We suggest that this deterioration in anticipatory control is associated with the increased demands of task complexity and attention during obstacle crossing. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Physical Abilities and Military Task Performance: A Replication and Extension

DTIC Science & Technology

2009-06-09

exertion lasted 3 s. Trapezius lift. Subject stood with feet at shoulder width grasping handles that were 38.5 cm apart to mimic the grip used in...maintained even with encouragement. Trapezius lift. The subject stood erect with his feet shoulder-width apart. He held a 20.9- kg load with his arms...static trunk extension; dynamic and static arm flexion; bench press, trapezius lift, leg extension; dynamic and static trunk flexion; right and left

Lunar surface operations. Volume 3: Robotic arm for lunar surface vehicle

NASA Technical Reports Server (NTRS)

Shields, William; Feteih, Salah; Hollis, Patrick

1993-01-01

A robotic arm for a lunar surface vehicle that can help in handling cargo and equipment, and remove obstacles from the path of the vehicle is defined as a support to NASA's intention to establish a lunar based colony by the year 2010. Its mission would include, but not limited to the following: exploration, lunar sampling, replace and remove equipment, and setup equipment (e.g. microwave repeater stations). Performance objectives for the robotic arm include a reach of 3 m, accuracy of 1 cm, arm mass of 100 kg, and lifting capability of 50 kg. The end effectors must grip various sizes and shapes of cargo; push, pull, turn, lift, or lower various types of equipment; and clear a path on the lunar surface by shoveling, sweeping aside, or gripping the obstacle present in the desired path. The arm can safely complete a task within a reasonable amount of time; the actual time is dependent upon the task to be performed. The positioning of the arm includes a manual backup system such that the arm can be safely stored in case of failure. Remote viewing and proximity and positioning sensors are incorporated in the design of the arm. The following specific topic are addressed in this report: mission and requirements, system design and integration, mechanical structure, modified wrist, structure-to-end-effector interface, end-effectors, and system controls.

Simplicity and treatment of the typical cleft hand.

PubMed

Upton, J

2004-01-01

The typical cleft hand is now distinguished from symbrachydactyly. This review of the surgical treatment of 108 hands in 63 patients treated over a 28-year period concentrates upon the technical principles of surgical correction. The key to these reconstructions is a wide incision which extends from the ulnar side of the cleft around the malpositioned index finger to the thumb. This wide exposure provides clear identification of all anatomic structures within the palm. There are no tenuous flaps with narrow random pedicles. These difficult surgical corrections may often include index transposition, metacarpal and/or phalangeal osteotomies, joint releases, phalangeal ostectomies, preservation of the adductor pollicis muscle, first dorsal interosseous muscle release, syndactyly separation(s) and thumb duplication correction. Following reposition of all skeletal structures the dorsal and palmar full-thickness flaps are easily contoured to create a satisfactory first webspace. Outcomes data shows that although the pinch and grip remain weak, these hands are quite functional. It is important that the repositioned index ray not interfere with gripping and precision maneuvers between the mobile thumb and the ulnar two digits (ring and small) of the hand.

Multiple regression analysis of factors influencing dominant hand grip strength in an adult Malaysian population.

PubMed

Hossain, M G; Zyroul, R; Pereira, B P; Kamarul, T

2012-01-01

Grip strength is an important measure used to monitor the progression of a condition, and to evaluate outcomes of treatment. We assessed how various physical and social factors predict normal grip strength in an adult Malaysian population of mixed Asian ethnicity (254 men, 246 women). Grip strength was recorded using the Jamar dynamometer. The mean grip strength for the dominant hand was 29.8 kg for men and 17.6 kg for women. Multiple regression analysis demonstrated that the dominant hand grip strength was positively associated with height and body mass index, and negatively associated with age for both sexes. Dominant hand grip strength was related to work status for men (p < 0.05) but not for women. However, there was no difference in grip strength among ethnic groups.

Quantification of hand function by power grip and pinch strength force measurements in ulnar nerve lesion simulated by ulnar nerve block.

PubMed

Wachter, Nikolaus Johannes; Mentzel, Martin; Krischak, Gert D; Gülke, Joachim

2017-06-24

In the assessment of hand and upper limb function, grip strength is of the major importance. The measurement by dynamometers has been established. In this study, the effect of a simulated ulnar nerve lesion on different grip force measurements was evaluated. In 25 healthy volunteers, grip force measurement was done by the JAMAR dynamometer (Fabrication Enterprises Inc, Irvington, NY) for power grip and by a pinch strength dynamometer for tip pinch strength, tripod grip, and key pinch strength. A within-subject research design was used in this prospective study. Each subject served as the control by preinjection measurements of grip and pinch strength. Subsequent measurements after ulnar nerve block were used to examine within-subject change. In power grip, there was a significant reduction of maximum grip force of 26.9% with ulnar nerve block compared with grip force without block (P < .0001). Larger reductions in pinch strength were observed with block: 57.5% in tip pinch strength (P < .0001), 61.0% in tripod grip (P < .0001), and 58.3% in key pinch strength (P < .0001). The effect of the distal ulnar nerve block on grip and pinch force could be confirmed. However, the assessment of other dimensions of hand strength as tip pinch, tripod pinch and key pinch had more relevance in demonstrating hand strength changes resulting from an distal ulnar nerve lesion. The measurement of tip pinch, tripod grip and key pinch can improve the follow-up in hand rehabilitation. II. Copyright © 2017 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Grips for Lightweight Tensile Specimens

NASA Technical Reports Server (NTRS)

Witte, William G., Jr.; Gibson, Walter D.

1987-01-01

Set of grips developed for tensile testing of lightweight composite materials. Double-wedge design substantially increases gripping force and reduces slippage. Specimen held by grips made of hardened wedges. Assembly screwed into load cell in tensile-testing machine.

Motor Consciousness during Intention-Based and Stimulus-Based Actions: Modulating Attention Resources through Mindfulness Meditation

PubMed Central

Delevoye-Turrell, Yvonne Nathalie; Bobineau, Claudie

2012-01-01

Mindfulness-Based Stress Reduction meditation (MBSR) may offer optimal performance through heightened attention for increased body consciousness. To test this hypothesis, MBSR effects were assessed on the simple task of lifting an object. A dual task paradigm was included to assess the opposite effect of a limited amount of attention on motor consciousness. In a stimulus-based condition, the subjects’ task was to lift an object that was hefted with weights. In an intentional-based condition, subjects were required to lift a light object while imagining that the object was virtually heavier and thus, adjust their grip voluntarily. The degree of motor consciousness was evaluated by calculating correlation factors for each participant between the grip force level used during the lift trial (“lift the object”) and that used during its associated reproduce trial (“without lifting, indicate the force you think you used in the previous trial”). Under dual task condition, motor consciousness decreased for intention- and stimulus-based actions, revealing the importance of top-down attention for building the motor representation that guides action planning. For MBSR-experts, heightened attention provided stronger levels of motor consciousness; this was true for both intention and stimulus-based actions. For controls, heightened attention decreased the capacity to reproduce force levels, suggesting that voluntary top-down attention interfered with the automatic bottom-up emergence of body sensations. Our results provide strong arguments for involvement of two types of attention for the emergence of motor consciousness. Bottom-up attention would serve as an amplifier of motor-sensory afferences; top-down attention would help transfer the motor-sensory content from a preconscious to a conscious state of processing. MBSR would be a specific state for which both types of attention are optimally combined to provide experts with total experiences of their body in movement. PMID:22973242

Visual-perceptual mismatch in robotic surgery.

PubMed

Abiri, Ahmad; Tao, Anna; LaRocca, Meg; Guan, Xingmin; Askari, Syed J; Bisley, James W; Dutson, Erik P; Grundfest, Warren S

2017-08-01

The principal objective of the experiment was to analyze the effects of the clutch operation of robotic surgical systems on the performance of the operator. The relative coordinate system introduced by the clutch operation can introduce a visual-perceptual mismatch which can potentially have negative impact on a surgeon's performance. We also assess the impact of the introduction of additional tactile sensory information on reducing the impact of visual-perceptual mismatch on the performance of the operator. We asked 45 novice subjects to complete peg transfers using the da Vinci IS 1200 system with grasper-mounted, normal force sensors. The task involves picking up a peg with one of the robotic arms, passing it to the other arm, and then placing it on the opposite side of the view. Subjects were divided into three groups: aligned group (no mismatch), the misaligned group (10 cm z axis mismatch), and the haptics-misaligned group (haptic feedback and z axis mismatch). Each subject performed the task five times, during which the grip force, time of completion, and number of faults were recorded. Compared to the subjects that performed the tasks using a properly aligned controller/arm configuration, subjects with a single-axis misalignment showed significantly more peg drops (p = 0.011) and longer time to completion (p < 0.001). Additionally, it was observed that addition of tactile feedback helps reduce the negative effects of visual-perceptual mismatch in some cases. Grip force data recorded from grasper-mounted sensors showed no difference between the different groups. The visual-perceptual mismatch created by the misalignment of the robotic controls relative to the robotic arms has a negative impact on the operator of a robotic surgical system. Introduction of other sensory information and haptic feedback systems can help in potentially reducing this effect.

Laboratory or field tests for evaluating firefighters' work capacity?

PubMed

Lindberg, Ann-Sofie; Oksa, Juha; Malm, Christer

2014-01-01

Muscle strength is important for firefighters work capacity. Laboratory tests used for measurements of muscle strength, however, are complicated, expensive and time consuming. The aims of the present study were to investigate correlations between physical capacity within commonly occurring and physically demanding firefighting work tasks and both laboratory and field tests in full time (N = 8) and part-time (N = 10) male firefighters and civilian men (N = 8) and women (N = 12), and also to give recommendations as to which field tests might be useful for evaluating firefighters' physical work capacity. Laboratory tests of isokinetic maximal (IM) and endurance (IE) muscle power and dynamic balance, field tests including maximal and endurance muscle performance, and simulated firefighting work tasks were performed. Correlations with work capacity were analyzed with Spearman's rank correlation coefficient (rs). The highest significant (p<0.01) correlations with laboratory and field tests were for Cutting: IE trunk extension (rs = 0.72) and maximal hand grip strength (rs = 0.67), for Stairs: IE shoulder flexion (rs = -0.81) and barbell shoulder press (rs = -0.77), for Pulling: IE shoulder extension (rs = -0.82) and bench press (rs = -0.85), for Demolition: IE knee extension (rs = 0.75) and bench press (rs = 0.83), for Rescue: IE shoulder flexion (rs = -0.83) and bench press (rs = -0.82), and for the Terrain work task: IE trunk flexion (rs = -0.58) and upright barbell row (rs = -0.70). In conclusion, field tests may be used instead of laboratory tests. Maximal hand grip strength, bench press, chin ups, dips, upright barbell row, standing broad jump, and barbell shoulder press were strongly correlated (rs≥0.7) with work capacity and are therefore recommended for evaluating firefighters work capacity.

Effects of grip force on skin conductance measured from a handheld device.

PubMed

Tartz, Robert; Vartak, Aniket; King, Jay; Fowles, Don

2015-01-01

Skin conductance (SC) reflects stimulus significance and can be measured by integrating electrodes directly onto a smartphone housing such that they are naturally contacted when gripped. However, grip artifacts naturally arise during operation since grip forces can vary. We explored the effects of grip force on SC to determine feasibility and to draw guidelines on artifact mitigation. For this purpose, a prototype was built with integrated SC electrodes with colocated force sensors, and data was collected from 24 participants gripping the prototype across different grip force conditions. Our analysis showed that static forces greater than 2.0 N were associated with significant SC distortion, and artifacts induced from dynamic grip forces were buffered if the SC level was at least 1.1 microsiemens. Our findings are relevant for future applications of SC sensing on smartphones, which may enable interesting and highly contextual user experiences. Copyright © 2014 Society for Psychophysiological Research.

Grip strength and its determinants among older people in different healthcare settings

PubMed Central

Roberts, Helen C; Syddall, Holly; Butchart, Joe; Sparkes, Jonathan; Ritchie, Jan; Kerr, Alastair; Cooper, Cyrus; Sayer, Avan Aihie

2013-01-01

Background Low muscle strength is central to geriatric syndromes including sarcopenia and frailty. It is well described in community dwelling older people but the epidemiology of grip strength of older people in rehabilitation or long term care has been little explored. Objective To describe grip strength of older people in rehabilitation and nursing home settings. Design Cross-sectional epidemiological study. Setting 3 healthcare settings in one town. Subjects 101 inpatients on a rehabilitation ward, 47 community rehabilitation referrals and 100 nursing home residents. Methods Grip strength, age, height, weight, body mass index, number of co-morbidities and medications, Barthel score, mini mental state examination (MMSE), nutritional status, and number of falls in the last year were recorded. Results Grip strength differed substantially between healthcare settings for both men and women (p<0.0001). Nursing home residents had the lowest age-adjusted mean grip strength and community rehabilitation referrals the highest. Broadly higher grip strength was associated in univariate analyses with younger age, greater height and weight, fewer comorbidities, higher Barthel score, higher MMSE score, better nutritional status and fewer falls. However after mutual adjustment for these factors, the difference in grip strength between settings remained significant. Barthel score was the characteristic most strongly associated with grip strength. Conclusions Older people in rehabilitation and care home settings had lower grip strength than reported for those living at home. Furthermore grip strength varied widely between healthcare settings independent of known major influences. Further research is required to ascertain whether grip strength may help identify people at risk of adverse health outcomes within these settings. PMID:23926093

ALTERED PHALANX FORCE DIRECTION DURING POWER GRIP FOLLOWING STROKE

PubMed Central

Enders, Leah R.

2015-01-01

Many stroke survivors with severe impairment can grasp only with a power grip. Yet, little knowledge is available on altered power grip after stroke, other than reduced power grip strength. This study characterized stroke survivors’ static power grip during 100% and 50% maximum grip. Each phalanx force’s angular deviation from the normal direction and its contribution to total normal force was compared for 11 stroke survivors and 11 age-matched controls. Muscle activities and skin coefficient of friction (COF) were additionally compared for another 20 stroke and 13 age-matched control subjects. The main finding was that stroke survivors gripped with a 34% greater phalanx force angular deviation of 19±2° compared to controls of 14±1° (p<.05). Stroke survivors’ phalanx force angular deviation was closer to the 23° threshold of slippage between the phalanx and grip surface, which may explain increased likelihood of object dropping in stroke survivors. In addition, this altered phalanx force direction decreases normal grip force by tilting the force vector, indicating a partial role of phalanx force angular deviation in reduced grip strength post stroke. Greater phalanx force angular deviation may biomechanically result from more severe underactivation of stroke survivors’ first dorsal interosseous (FDI) and extensor digitorum communis (EDC) muscles compared to their flexor digitorum superficialis (FDS) or somatosensory deficit. While stroke survivors’ maximum power grip strength was approximately half of the controls’, the distribution of their remaining strength over the fingers and phalanges did not differ, indicating evenly distributed grip force reduction over the entire hand. PMID:25795079

Notes From the Field: Secondary Task Precision for Cognitive Load Estimation During Virtual Reality Surgical Simulation Training.

PubMed

Rasmussen, Sebastian R; Konge, Lars; Mikkelsen, Peter T; Sørensen, Mads S; Andersen, Steven A W

2016-03-01

Cognitive load (CL) theory suggests that working memory can be overloaded in complex learning tasks such as surgical technical skills training, which can impair learning. Valid and feasible methods for estimating the CL in specific learning contexts are necessary before the efficacy of CL-lowering instructional interventions can be established. This study aims to explore secondary task precision for the estimation of CL in virtual reality (VR) surgical simulation and also investigate the effects of CL-modifying factors such as simulator-integrated tutoring and repeated practice. Twenty-four participants were randomized for visual assistance by a simulator-integrated tutor function during the first 5 of 12 repeated mastoidectomy procedures on a VR temporal bone simulator. Secondary task precision was found to be significantly lower during simulation compared with nonsimulation baseline, p < .001. Contrary to expectations, simulator-integrated tutoring and repeated practice did not have an impact on secondary task precision. This finding suggests that even though considerable changes in CL are reflected in secondary task precision, it lacks sensitivity. In contrast, secondary task reaction time could be more sensitive, but requires substantial postprocessing of data. Therefore, future studies on the effect of CL modifying interventions should weigh the pros and cons of the various secondary task measurements. © The Author(s) 2015.

Competing with the Cartels: How Mexico’s Government Can Reduce Organized Crime’s Economic Grip on its People

DTIC Science & Technology

2011-10-28

any other provision of law , no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a...police and military units to regain control. Unfortunately, the security forces’ efforts to reestablish law and order have largely failed, and the...situation in anticipation of possible future taskings to assist Mexican military and law enforcement agencies. Regardless of what is decided

Pencil grips, legibility, and speed of fourth-graders' writing in cursive.

PubMed

Koziatek, Susan M; Powell, Nancy J

2003-01-01

The purpose of this research was to study how the speed and legibility of fourth-graders handwriting was affected by type of pencil grip on the Evaluation Tool of Children's Handwriting-Cursive. Ninety-five typically developing students and 6 students receiving special education services completed the Evaluation Tool of Children's Handwriting-Cursive (ETCH-C). Photographs were taken of their pencil grips while they wrote the alphabet. One-way ANOVAs were calculated to compare legibility rates and writing speeds by type of pencil grip. Ninety-nine of the students used one of four pencil grips including the dynamic tripod (38 students), the dynamic quadrupod (18), the lateral tripod (22), and the lateral quadrupod (21). One student used the four-finger pencil grip and one used the interdigital pencil grip. Mean cursive writing speeds were similar for all pencil grips except for the interdigital grasp. Speeds obtained were slower than recently published fourth-grade speeds ranging from a mean of 29.45 to 34.75 letters per minute. CONCLUSION. This study found the lateral quadrupod and four-finger pencil grips to be as functional as the dynamic tripod, lateral tripod, and dynamic quadrupod pencil grips. This study provides average handwriting speeds for fourth-grade students on the ETCH-C.

Using ergonomics to enhance safe production at a surface coal mine--a case study with powder crews.

PubMed

Torma-Krajewski, Janet; Wiehagen, William; Etcheverry, Ann; Turin, Fred; Unger, Richard

2009-10-01

Job tasks that involve exposure to work-related musculoskeletal disorder (WMSD) risk factors may impact both the risk of injury and production downtime. Common WMSD risks factors associated with mining tasks include forceful exertions, awkward postures, repetitive motion, jolting and jarring, forceful gripping, contact stress, and whole body and segmental vibration. Mining environments that expose workers to temperature/humidity extremes, windy conditions, and slippery and uneven walking surfaces also contribute to injury risk. National Institute for Occupational Safety and Health (NIOSH) researchers worked with powder crew members from the Bridger Coal Company to identify and rank routine work tasks based on perceived exposure to WMSD risk factors. This article presents the process followed to identify tasks that workers believed involved the greatest exposure to risk factors and discusses risk reduction strategies. Specifically, the proposed prill truck design changes addressed cab ingress/egress, loading blast holes, and access to the upper deck of the prill truck.

Individuals with autism spectrum disorder show abnormalities during initial and subsequent phases of precision gripping

PubMed Central

Magnon, Grant C.; White, Stormi P.; Greene, Rachel K.; Vaillancourt, David E.

2014-01-01

Sensorimotor impairments are common in autism spectrum disorder (ASD), but they are not well understood. Here we examined force control during initial pulses and the subsequent rise, sustained, and relaxation phases of precision gripping in 34 individuals with ASD and 25 healthy control subjects. Participants pressed on opposing load cells with their thumb and index finger while receiving visual feedback regarding their performance. They completed 2- and 8-s trials during which they pressed at 15%, 45%, or 85% of their maximum force. Initial pulses guided by feedforward control mechanisms, sustained force output controlled by visual feedback processes, and force relaxation rates all were examined. Control subjects favored an initial pulse strategy characterized by a rapid increase in and then relaxation of force when the target force was low (Type 1). When the target force level or duration of trials was increased, control subjects transitioned to a strategy in which they more gradually increased their force, paused, and then increased their force again. Individuals with ASD showed a more persistent bias toward the Type 1 strategy at higher force levels and during longer trials, and their initial force output was less accurate than that of control subjects. Patients showed increased force variability compared with control subjects when attempting to sustain a constant force level. During the relaxation phase, they showed reduced rates of force decrease. These findings suggest that both feedforward and feedback motor control mechanisms are compromised in ASD and these deficits may contribute to the dyspraxia and sensorimotor abnormalities often seen in this disorder. PMID:25552638

How to classify plantar plate injuries: parameters from history and physical examination.

PubMed

Nery, Caio; Coughlin, Michael; Baumfeld, Daniel; Raduan, Fernando; Mann, Tania Szejnfeld; Catena, Fernanda

2015-01-01

To find the best clinical parameters for defining and classifying the degree of plantar plate injuries. Sixty-eight patients (100 metatarsophalangeal joints) were classified in accordance with the Arthroscopic Anatomical Classification for plantar plate injuries and were divided into five groups (0 to IV). Their medical files were reviewed and the incidence of each parameter for the respective group was correlated. These parameters were: use of high heels, sports, acute pain, local edema, Mulder's sign, widening of the interdigital space, pain in the head of the corresponding metatarsal, touching the ground, "drawer test", toe grip and toe deformities (in the sagittal, coronal and transversal planes). There were no statistically significant associations between the degree of injury and use of high-heel shoes, sports trauma, pain at the head of the metatarsal, Mulder's sign, deformity in pronation or displacement in the transversal and sagittal planes (although their combination, i.e. "cross toe", showed a statistically significant correlation). Positive correlations with the severity of the injuries were found in relation to initial acute pain, progressive widening of the interdigital space, loss of "touching the ground", positive results from the "drawer test" on the metatarsophalangeal joint, diminished grip strength and toe deformity in supination. The "drawer test" was seen to be the more reliable and precise tool for classifying the degree of plantar plate injury, followed by "touching the ground" and rotational deformities. It is possible to improve the precision of the diagnosis and the predictions of the anatomical classification for plantar plate injuries through combining the clinical history and data from the physical examination.

The destination defines the journey: an examination of the kinematics of hand-to-mouth movements

PubMed Central

Gonzalez, Claudia L. R.

2016-01-01

Long-train electrical stimulation of the motor and premotor cortices of nonhuman primates can produce either hand-to-mouth or grasp-to-inspect movements, depending on the precise location of stimulation. Furthermore, single-neuron recording studies identify discrete neuronal populations in the inferior parietal and ventral premotor cortices that respond uniquely to either grasp-to-eat or grasp-to-place movements, despite their identical mechanistic requirements. These studies demonstrate that the macaque motor cortex is organized around producing functional, goal-oriented movements, rather than simply fulfilling muscular prerequisites of action. In humans, right-handed hand-to-mouth movements have a unique kinematic signature; smaller maximum grip apertures are produced when grasping to eat than when grasping to place identical targets. This is evidence that the motor cortex in humans is also organized around producing functional movements. However, in both macaques and humans, grasp-to-eat/hand-to-mouth movements have always been elicited using edible targets and have (necessarily) been paired with mouth movement. It is therefore unknown whether the kinematic distinction is a natural result of grasping food and/or is simply attributable to concurrent opening of the mouth while grasping. In experiment 1, we used goal-differentiated grasping tasks, directed toward edible and inedible targets, to show that the unique kinematic signature is present even with inedible targets. In experiment 2, we used the same goal-differentiated grasping tasks, either coupled with or divorced from an open-mouth movement, to show that the signature is not attributable merely to a planned opening of the mouth during the grasp. These results are discussed in relation to the role of hand-to-mouth movements in human development, independently of grasp-to-eat behavior. PMID:27512020

Gravity-dependent estimates of object mass underlie the generation of motor commands for horizontal limb movements.

PubMed

Crevecoeur, F; McIntyre, J; Thonnard, J-L; Lefèvre, P

2014-07-15

Moving requires handling gravitational and inertial constraints pulling on our body and on the objects that we manipulate. Although previous work emphasized that the brain uses internal models of each type of mechanical load, little is known about their interaction during motor planning and execution. In this report, we examine visually guided reaching movements in the horizontal plane performed by naive participants exposed to changes in gravity during parabolic flight. This approach allowed us to isolate the effect of gravity because the environmental dynamics along the horizontal axis remained unchanged. We show that gravity has a direct effect on movement kinematics, with faster movements observed after transitions from normal gravity to hypergravity (1.8g), followed by significant movement slowing after the transition from hypergravity to zero gravity. We recorded finger forces applied on an object held in precision grip and found that the coupling between grip force and inertial loads displayed a similar effect, with an increase in grip force modulation gain under hypergravity followed by a reduction of modulation gain after entering the zero-gravity environment. We present a computational model to illustrate that these effects are compatible with the hypothesis that participants partially attribute changes in weight to changes in mass and scale incorrectly their motor commands with changes in gravity. These results highlight a rather direct internal mapping between the force generated during stationary holding against gravity and the estimation of inertial loads that limb and hand motor commands must overcome. Copyright © 2014 the American Physiological Society.

Comparative study of millennials' (age 20-34 years) grip and lateral pinch with the norms.

PubMed

Fain, Elizabeth; Weatherford, Cara

Cross-sectional research design. Clinical practice continues to use normative data for grip and pinch measurements that were established in 1985. There is no updated norms despite different hand usage patterns in today's society. Measuring and comparing grip and pinch strengths with normative data is a valid method to determine hand function. This research was implemented to compare the grip and pinch measurements obtained from healthy millennials to the established norms and to describe hand usage patterns for millennials. Grip and lateral pinch measurements were obtained from a sample of 237 healthy millennials (ages 20-34 years). Strength scores were statistically lower that older normative data in all millennial grip strengths, with the exception of the women in the age group of 30-34 years. Specifically, this statistically significant trend was observed in all male grip strengths, as well as in women in the age group of 20-24 years (bilateral grip) and 25-29 years (right grip). However, the lateral pinch data reflected was similar to the older norms with variances of 0.5-1 kg. Current data reflect statistically significant differences from the norms for all male grip measurements, as well as for women in the age group of 20-24 years (bilateral grip) and 25-29 years (right grip). No statistical significance was observed in the independent-sample t tests for the lateral pinch in men of all age groups. Statistical significance was noted for lateral pinch for female age groups for the left hand (20-24 years) and for bilateral lateral pinches (30-34 years). IV. Copyright © 2016 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

Mobility of the elastic counterpressure space suit glove.

PubMed

Tanaka, Kunihiko; Danaher, Patrick; Webb, Paul; Hargens, Alan R

2009-10-01

To evaluate the mobility of the current gas-pressurized glove of the extravehicular mobility unit (G-glove) and the elastic counterpressure glove (E-glove), we investigated range of motion (ROM) and indices of fatigue during grip endurance with both gloves using a bare hand as a control. In nine healthy male right-handed subjects, ROM of the proximal interphalangeal joint of the left middle finger was measured. The median frequency of electromyography (EMG) of the left flexor carpi radialis during grip with 25% of maximum strength was measured with the bare hand, G-glove, and E-glove. Using Borg's scale, discomfort was assessed during each grip test. ROM of the E-glove was similar to that of the bare hand (91 +/- 3 degrees and 97 +/- 1 degree for the E-glove and bare hand, respectively) and significantly higher than that of the G-glove (74 +/- 2 degrees). The change in the median frequency of the EMG, which is correlated with Borg's scale, was significantly smaller using the E-glove at marker time points of 1/4 and 1/2 of the total endurance time (-3.5 +/- 1.5 and -10.4 +/- 1.2 Hz) compared to those for the G-glove (-10.1 +/- 1.1 and -16.7 +/- 1.9 Hz). Thus, the G-glove had faster onset of fatigue than the E-glove. These results suggest the E-glove has better mobility and is more suitable for fine motor tasks as compared to the G-glove.

Design and validation of the Grip-ball for measurement of hand grip strength.

PubMed

Jaber, Rana; Hewson, David J; Duchêne, Jacques

2012-11-01

The Grip-ball is a new dynamometer used to evaluate grip strength, as well as for use in home-based rehabilitation of the hand and forearm. The Grip-ball consists of pressure and temperature sensors and an electronic wireless communication system contained in an airtight ball. That can be inflated to different pressures. The device has advantages over standard dynamometers in that it looks like a simple ball, and can wirelessly communicate via Bluetooth to any compatible receiver, thus have potential to be used for clinical assessment and rehabilitation in a remote setting. The reliability and reproducibility of the device were assessed for the pressure sensor itself, as well as the relationship between the force applied and the pressure measured by the Grip-ball. The initial validation was performed using the pressure sensor without the ball in order to confirm the accuracy of the sensor used. A second validation study was conducted using the Grip-ball rather than just its sensor to examine the relationship between the pressure measured inside the ball and force applied. The results showed that there is a very good correlation (r=0.997, p<0.05) between the pressure measured by the Grip-ball sensor and that measured by a Vigorimeter, thus confirming the reliability of the sensor used in the Grip-ball. A quadratic regression equation was calculated in order to predict the force applied based on the pressure measured inside the ball, and the initial pressure to which the ball was inflated (R(2)=0.97, standard error 10.9N). Such a finding compares favourably with the variability inherent in Jamar recordings, thus indicating that the Grip-ball could be used to assess grip force. An industrial version of the Grip-ball, which is currently under development, will be able to be used for the entire range of grip force in the population. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

An electromyographic study of the effect of hand grip sizes on forearm muscle activity and golf performance.

PubMed

Sorbie, Graeme G; Hunter, Henry H; Grace, Fergal M; Gu, Yaodong; Baker, Julien S; Ugbolue, Ukadike Chris

2016-01-01

The study describes the differences in surface electromyography (EMG) activity of two forearm muscles in the lead and trail arm at specific phases of the golf swing using a 7-iron with three different grip sizes among amateur and professional golfers. Fifteen right-handed male golfers performed five golf swings using golf clubs with three different grip sizes. Surface EMG was used to measure muscle activity of the extensor carpi radialis brevis (ECRB) and flexor digitorum superficialis (FDS) on both forearms. There were no significant differences in forearm muscle activity when using the three golf grips within the group of 15 golfers (p > 0.05). When using the undersize grip, club head speed significantly increased (p = 0.044). During the backswing and downswing phases, amateurs produced significantly greater forearm muscle activity with all three grip sizes (p < 0.05). In conclusion, forearm muscle activity is not affected by grip sizes. However, club head speed increases when using undersize grips.

Repeated exposures to chlorpyrifos lead to spatial memory retrieval impairment and motor activity alteration.

PubMed

Yan, Changhui; Jiao, Lifei; Zhao, Jun; Yang, Haiying; Peng, Shuangqing

2012-07-01

Chlorpyrifos (CPF) is one of the most commonly used insecticides throughout the world and has become one of the major pesticides detected in farm products. Chronic exposures to CPF, especially at the dosages without eliciting any systemic toxicity, require greater attention. The purpose of this study was, therefore, to evaluate the behavioral effects of repeated low doses (doses that do not produce overt signs of cholinergic toxicity) of CPF in adult rats. Male rats were given 0, 1.0, 5.0 or 10.0mg/kg of CPF through intragastric administration daily for 4 consecutive weeks. The behavioral functions were assessed in a series of behavioral tests, including water maze task, open-field test, grip strength and rotarod test. Furthermore, the present study was designed to evaluate the effects of repeated exposures to CPF on water maze recall and not acquisition. The results showed that the selected doses only had mild inhibition effects on cholinesterase activity, and have no effects on weight gain and daily food consumption. Performances in the spatial retention task (Morris water maze) were impaired after the 4-week exposure to CPF, but the performances of grip strength and rotarod test were not affected. Motor activities in the open field were changed, especially the time spent in the central zone increased. The results indicated that repeated exposures to low doses of CPF may lead to spatial recall impairments, behavioral abnormalities. However, the underlying mechanism needs further investigations. Copyright © 2012 Elsevier Inc. All rights reserved.

The relationship between hand paraesthesia and occupational factors: results from a population study.

PubMed

Lacey, R J; Lewis, M; Sim, J

2005-10-01

To investigate the association of occupational factors, both physical and psychosocial, with hand paraesthesia, and whether any such associations differ according to the concurrent presence of neck and upper limb pain (NULP). A questionnaire was mailed to an age-stratified random sample of 9596 adults. All subjects were asked about hand paraesthesia in the past 4 weeks. Information was obtained on respondents' main job (the job held for the longest time), whether this job involved any of six neck or upper limb activities on most or all days of the working week, and questions on the psychosocial aspects of the work environment. The questionnaire also asked about NULP according to a preshaded manikin. A total of 5133 people replied to the survey (adjusted response 53.5%). Of these, 1592 reported abnormal feelings in the hands (prevalence of 31.9%). Prolonged gripping, prolonged bending of the neck forwards, working with arms at/above shoulder height, low job control, many changes in tasks and low job support were independently associated with hand paraesthesia. Among responders also reporting NULP, working with arms at/above shoulder height and many changes in tasks were independently associated with hand paraesthesia; prolonged gripping was linked to hand paraesthesia in the absence of NULP. Hand paraesthesia is associated with physical and psychosocial workplace factors, although different work-related factors were associated with hand paraesthesia according to the concurrent presence of NULP, suggesting that these symptoms may not always be mediated in the same way.

Choose, rate or squeeze: Comparison of economic value functions elicited by different behavioral tasks

PubMed Central

Pessiglione, Mathias

2017-01-01

A standard view in neuroeconomics is that to make a choice, an agent first assigns subjective values to available options, and then compares them to select the best. In choice tasks, these cardinal values are typically inferred from the preference expressed by subjects between options presented in pairs. Alternatively, cardinal values can be directly elicited by asking subjects to place a cursor on an analog scale (rating task) or to exert a force on a power grip (effort task). These tasks can vary in many respects: they can notably be more or less costly and consequential. Here, we compared the value functions elicited by choice, rating and effort tasks on options composed of two monetary amounts: one for the subject (gain) and one for a charity (donation). Bayesian model selection showed that despite important differences between the three tasks, they all elicited a same value function, with similar weighting of gain and donation, but variable concavity. Moreover, value functions elicited by the different tasks could predict choices with equivalent accuracy. Our finding therefore suggests that comparable value functions can account for various motivated behaviors, beyond economic choice. Nevertheless, we report slight differences in the computational efficiency of parameter estimation that may guide the design of future studies. PMID:29161252

F-16 Task Analysis Criterion-Referenced Objective and Objectives Hierarchy Report. Volume 4

DTIC Science & Technology

1981-03-01

Initiation cues: Engine flameout Systems presenting cues: Aircraft fuel, engine STANDARD: Authority: TACR 60-2 Performance precision: TD in first 1/3 of...task: None Initiation cues: On short final Systems preventing cues: N/A STANDARD: Authority: 60-2 Performance precision: +/- .5 AOA; TD zone 150-1000...precision: +/- .05 AOA; TD Zone 150-1000 Computational accuracy: N/A ... . . ... . ... e e m I TASK NO.: 1.9.4 BEHAVIOR: Perform short field landing

Mechanical counter-pressure vs. gas-pressurized spacesuit gloves: grip and sensitivity.

PubMed

Danaher, Patrick; Tanaka, Kunihiko; Hargens, Alan R

2005-04-01

An elastic mechanical counter pressure (MCP) glove for spacesuits is under development. In this study we compared handgrip and pinch grip strength levels for the MCP glove and the current extravehicular mobility unit (EMU) gas-pressurized glove. We employed handgrip and pinch grip dynamometers to assess strength levels and von Frey monofilaments to evaluate hand sensitivity. Tests were conducted with the gloved hand inserted in an evacuation chamber at 200 mmHg below atmospheric pressure to simulate conditions in space. Average bare hand strength was 463 N and decreased to 240 N for EMU and 250 N for MCP. Pinch grip and key grip testing showed no difference among conditions. However, there was a significant decrease in palmar grip strength from 111 N barehanded to 67 N in both gloves. Barehanded endurance time was 160 s and dropped to 63 and 69 s for EMU and MCP, respectively. Sensitivity was significantly better for MCP compared with the EMU. The MCP glove improved hand sensitivity when compared with the EMU glove and performed as well as the EMU glove in terms of overall handgrip strength, endurance at 25% of maximum handgrip strength, pinch grip, palmar grip, and key grip tests. Improvements in fabric composition and glove design may further improve ergonomic and other functional parameters of the MCP glove.

Effect of custom-made and prefabricated orthoses on grip strength in persons with carpal tunnel syndrome.

PubMed

Mlakar, Maja; Ramstrand, Nerrolyn; Burger, Helena; Vidmar, Gaj

2014-06-01

Based on the literature, patients with carpal tunnel syndrome are suggested to wear a custom-made wrist orthosis immobilizing the wrist in a neutral position. Many prefabricated orthoses are available on the market, but the majority of those do not assure neutral wrist position. We hypothesized that the use of orthosis affects grip strength in persons with carpal tunnel syndrome in a way that supports preference for custom-made orthoses with neutral wrist position over prefabricated orthoses. Experimental. Comparisons of grip strength for three types of grips (cylindrical, lateral, and pinch) were made across orthosis types (custom-made, prefabricated with wrist in 20° of flexion, and none) on the affected side immediately after fitting, as well as between affected side without orthosis and nonaffected side. Orthosis type did not significantly affect grip strength (p = 0.661). Cylindrical grip was by far the strongest, followed by lateral and pinch grips (p < 0.050). The grips of the affected side were weaker than those of the nonaffected side (p = 0.002). In persons with carpal tunnel syndrome, neither prefabricated orthoses with 20° wrist extension nor custom-made wrist orthoses with neutral wrist position influenced grip strength of the affected hand. Compared to the nonaffected side, the grips of the affected side were weaker. The findings from this study can be used to guide application of orthoses to patients with carpal tunnel syndrome. © The International Society for Prosthetics and Orthotics 2013.

Effects of hand grip exercise on shoulder joint internal rotation and external rotation peak torque.

PubMed

Lee, Dong-Rour; Jong-Soon Kim, Laurentius

2016-08-10

The goal of this study is to analyze the effects of hand grip training on shoulder joint internal rotation (IR)/external rotation (ER) peak torque for healthy people. The research was conducted on 23 healthy adults in their 20 s-30 s who volunteered to participate in the experiment. Hand grip power test was performed on both hands of the research subjects before/after the test to study changes in hand grip power. Isokinetic machine was used to measure the concentric IRPT (internal rotation peak torque) and concentric ERPT (external rotation peak torque) at the velocity of 60°/sec, 90°/sec, and 180°/sec before/after the test. Hand grip training was performed daily on the subject's right hand only for four weeks according to exercise program. Finally, hand grip power of both hands and the maximum torque values of shoulder joint IR/ER were measured before/after the test and analyzed. There was a statistically significant difference in the hand grip power of the right hand, which was subject to hand grip training, after the experiment. Also, statistically significant difference for shoulder ERPT was found at 60°/sec. Hand grip training has a positive effect on shoulder joint IRPT/ERPT and therefore can help strengthen muscles around the shoulder without using weight on the shoulder. Consequently, hand grip training would help maintain strengthen the muscles around the shoulder in the early phase of rehabilitation process after shoulder surgery.

The Effects of Bench Press Variations in Competitive Athletes on Muscle Activity and Performance

PubMed Central

Saeterbakken, Atle Hole; Mo, Dag-André; Scott, Suzanne; Andersen, Vidar

2017-01-01

Abstract The aim of the study was to compare the EMG activity performing 6RM competition style bench press (flat bench-wide grip) with 1) medium and narrow grip widths on a flat bench and 1) inclined and declined bench positions with a wide grip. Twelve bench press athletes competing at national and international level participated in the study. EMG activity was measured in the pectoralis major, anterior and posterior deltoid, biceps brachii, triceps brachii and latissimus dorsi. Non-significant differences in activation were observed between the three bench positions with the exception of 58.5-62.6% lower triceps brachii activation, but 48.3-68.7% greater biceps brachii activation in the inclined bench compared with the flat and declined bench position. Comparing the three grip widths, non-significant differences in activations were observed, with the exception of 25.9-30.5% lower EMG activity in the biceps brachii using a narrow grip, compared to the medium and wide grip conditions. The 6-RM loads were 5.8-11.1% greater using a medium and wide grip compared to narrow grip width and 18.5-21.5% lower in the inclined bench position compared with flat and declined. Comparing the EMG activity during the competition bench press style with either the inclined and declined bench position (wide grip) or using a narrow and medium grip (flat bench), only resulted in different EMG activity in the biceps- and triceps brachii. The 6RM loads varied with each bench press variation and we recommend the use of a wide grip on a flat bench during high load hypertrophy training to bench press athletes. PMID:28713459

The Effects of Bench Press Variations in Competitive Athletes on Muscle Activity and Performance.

PubMed

Saeterbakken, Atle Hole; Mo, Dag-André; Scott, Suzanne; Andersen, Vidar

2017-06-01

The aim of the study was to compare the EMG activity performing 6RM competition style bench press (flat bench-wide grip) with 1) medium and narrow grip widths on a flat bench and 1) inclined and declined bench positions with a wide grip. Twelve bench press athletes competing at national and international level participated in the study. EMG activity was measured in the pectoralis major, anterior and posterior deltoid, biceps brachii, triceps brachii and latissimus dorsi. Non-significant differences in activation were observed between the three bench positions with the exception of 58.5-62.6% lower triceps brachii activation, but 48.3-68.7% greater biceps brachii activation in the inclined bench compared with the flat and declined bench position. Comparing the three grip widths, non-significant differences in activations were observed, with the exception of 25.9-30.5% lower EMG activity in the biceps brachii using a narrow grip, compared to the medium and wide grip conditions. The 6-RM loads were 5.8-11.1% greater using a medium and wide grip compared to narrow grip width and 18.5-21.5% lower in the inclined bench position compared with flat and declined. Comparing the EMG activity during the competition bench press style with either the inclined and declined bench position (wide grip) or using a narrow and medium grip (flat bench), only resulted in different EMG activity in the biceps- and triceps brachii. The 6RM loads varied with each bench press variation and we recommend the use of a wide grip on a flat bench during high load hypertrophy training to bench press athletes.

Cognitive and Physical Fatigue Tasks Enhance Pain, Cognitive Fatigue and Physical Fatigue in People with Fibromyalgia

PubMed Central

Dailey, Dana L; Keffala, Valerie J; Sluka, Kathleen A

2014-01-01

Objective Fibromyalgia is a condition characterized by chronic widespread muscle pain and fatigue. The primary objective of this study was to determine if pain, perceived cognitive fatigue, and perceived physical fatigue were enhanced in participants with fibromyalgia compared to healthy controls during a cognitive fatigue task, a physical fatigue task and a dual fatigue task. Methods Twenty four people with fibromyalgia and 33 healthy controls completed pain, fatigue and function measures. A cognitive fatigue task (Controlled Oral Word Association Test) and physical fatigue task (Valpar peg test) were done individually and combined for a dual fatigue task. Resting pain, perceived cognitive fatigue and perceived physical fatigue were assessed during each task using visual analogue scales. Function was assessed with shoulder range of motion and grip. Results People with fibromyalgia had significantly higher increases in pain, cognitive fatigue and physical fatigue when compared to healthy controls after completion of a cognitive fatigue task, a physical fatigue task, or a dual fatigue task (p<0.01). People with fibromyalgia performed equivalently on measures of physical performance and cognitive performance on the physical and cognitive fatigue tasks, respectively. Conclusions These data show that people with fibromyalgia show larger increases in pain, perceived cognitive fatigue and perceived physical fatigue to both cognitive and physical fatigue tasks compared to healthy controls. The increases in pain and fatigue during cognitive and physical fatigue tasks could influence subject participation in daily activities and rehabilitation. PMID:25074583

Effect of yoga on musculoskeletal discomfort and motor functions in professional computer users.

PubMed

Telles, Shirley; Dash, Manoj; Naveen, K V

2009-01-01

The self-rated musculoskeletal discomfort, hand grip strength, tapping speed, and low back and hamstring flexibility (based on a sit and reach task) were assessed in 291 professional computer users. They were then randomized as Yoga (YG; n=146) and Wait-list control (WL; n=145) groups. Follow-up assessments for both groups were after 60 days during which the YG group practiced yoga for 60 minutes daily, for 5 days in a week. The WL group spent the same time in their usual recreational activities. At the end of 60 days, the YG group (n=62) showed a significant decrease in the frequency, intensity and degree of interference due to musculoskeletal discomfort, an increase in bilateral hand grip strength, the right hand tapping speed, and low back and hamstring flexibility (repeated measures ANOVA and post hoc analysis with Bonferroni adjustment). In contrast, the WL group (n=56) showed an increase in musculoskeletal discomfort and a decrease in left hand tapping speed. The results suggest that yoga practice is a useful addition to the routine of professional computer users.

Reframing the action and perception dissociation in DF: haptics matters, but how?

PubMed

Whitwell, Robert L; Buckingham, Gavin

2013-02-01

Goodale and Milner's (1992) "vision-for-action" and "vision-for-perception" account of the division of labor between the dorsal and ventral "streams" has come to dominate contemporary views of the functional roles of these two pathways. Nevertheless, some lines of evidence for the model remain controversial. Recently, Thomas Schenk reexamined visual form agnosic patient DF's spared anticipatory grip scaling to object size, one of the principal empirical pillars of the model. Based on this new evidence, Schenk rejects the original interpretation of DF's spared ability that was based on segregated processing of object size and argues that DF's spared grip scaling relies on haptic feedback to calibrate visual egocentric cues that relate the posture of the hand to the visible edges of the goal-object. However, a careful consideration of the tasks that Schenk employed reveals some problems with his claim. We suspect that the core issues of this controversy will require a closer examination of the role that cognition plays in the operation of the dorsal and ventral streams in healthy controls and in patient DF.

A glove-likeability study of specially-treated gloves in the detonator manufacturing and packaging industry

DOE PAGES

Cournoyer, Michael E.; Lawton, Cindy M.; Lounsbury, James B.; ...

2016-03-22

We use hand gloves (hereafter referred to as gloves) in the detonator manufacturing and packaging operations. As part of a process improvement program, new glove formulations have been considered that lower the overall risk of detonator operations by reducing ergonomic injury factors. Gloves with a specially treated surface for extra grip and control are now commercially available and have been recommended for use in detonator operations. A Glove Likeability Study demonstrated that detonator manufacturing and packaging workers prefer gloves with a specially treated surface over currently approved gloves made from latex and nitrile formulations. Glove material compatibility tests indicate thatmore » the recommended gloves are as compatible if not more compatible as the currently approved gloves for working with secondary explosives. Thus, these gloves with a specially treated surface for extra grip and control are now available for tasks where sensitivity and fingertip control are crucial. Replacement of the current gloves with gloves with a specially treated surface improves the safety configuration of detonator manufacturing and packaging operations.« less

A glove-likeability study of specially-treated gloves in the detonator manufacturing and packaging industry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cournoyer, Michael E.; Lawton, Cindy M.; Lounsbury, James B.

We use hand gloves (hereafter referred to as gloves) in the detonator manufacturing and packaging operations. As part of a process improvement program, new glove formulations have been considered that lower the overall risk of detonator operations by reducing ergonomic injury factors. Gloves with a specially treated surface for extra grip and control are now commercially available and have been recommended for use in detonator operations. A Glove Likeability Study demonstrated that detonator manufacturing and packaging workers prefer gloves with a specially treated surface over currently approved gloves made from latex and nitrile formulations. Glove material compatibility tests indicate thatmore » the recommended gloves are as compatible if not more compatible as the currently approved gloves for working with secondary explosives. Thus, these gloves with a specially treated surface for extra grip and control are now available for tasks where sensitivity and fingertip control are crucial. Replacement of the current gloves with gloves with a specially treated surface improves the safety configuration of detonator manufacturing and packaging operations.« less

Progression of motor deficits in glioma-bearing mice: impact of CNF1 therapy at symptomatic stages

PubMed Central

Fabbri, Alessia; Costa, Mario; Caleo, Matteo; Baroncelli, Laura

2017-01-01

Glioblastoma (GBM) is the most aggressive type of brain tumor. In this context, animal models represent excellent tools for the early detection and longitudinal mapping of neuronal dysfunction, that are critical in the preclinical validation of new therapeutic strategies. In a mouse glioma model, we developed sensitive behavioral readouts that allow early recognizing and following neurological symptoms. We injected GL261 cells into the primary motor cortex of syngenic mice and we used a battery of behavioral tests to longitudinally monitor the dysfunction induced by tumor growth. Grip strength test revealed an early onset of functional deficit associated to the glioma growth, with a significant forelimb weakness appearing 9 days after tumor inoculation. A later deficit was observed in the rotarod and in the grid walk tasks. Using this model, we found reduced tumor growth and maintenance of behavioral functions following treatment with Cytotoxic Necrotizing Factor 1 (CNF1) at a symptomatic stage. Our data provide a detailed and precise examination of how tumor growth reverberates on the behavioral functions of glioma-bearing mice, providing normative data for the study of therapeutic strategies for glioma treatment. The reduced tumor volume and robust functional sparing observed in CNF1-treated, glioma-bearing mice strengthen the notion that CNF1 delivery is a promising strategy for glioma therapy. PMID:28212563

Kinematic cues in perceptual weight judgement and their origins in box lifting

PubMed Central

Hamilton, A.; Joyce, D. W.; Flanagan, R.; Frith, C. D.; Wolpert, D. M.

2009-01-01

When accepting a parcel from another person, we are able to use information about that person’s movement to estimate in advance the weight of the parcel, that is, to judge its weight from observed action. Perceptual weight judgment provides a powerful method to study our interpretation of other people’s actions, but it is not known what sources of information are used in judging weight. We have manipulated full form videos to obtain precise control of the perceived kinematics of a box lifting action, and use this technique to explore the kinematic cues that affect weight judgment. We find that observers rely most on the duration of the lifting movement to judge weight, and make less use of the durations of the grasp phase, when the box is first gripped, or the place phase, when the box is put down. These findings can be compared to the kinematics of natural box lifting behaviour, where we find that the duration of the grasp component is the best predictor of true box weight. The lack of accord between the optimal cues predicted by the natural behaviour and the cues actually used in the perceptual task has implications for our understanding of action observation in terms of a motor simulation. The differences between perceptual and motor behaviour are evidence against a strong version of the motor simulation hypothesis. PMID:16311765

Hand anthropometry of Indian women.

PubMed

Nag, Anjali; Nag, P K; Desai, Hina

2003-06-01

Data on the physical dimension of the hand of Indian women are scanty. This information is necessary to ascertain human-machine compatibility in the design of manual systems for the bare and gloved hand, such as design and sizing of hand tools, controls, knobs and other applications in different kinds of precision and power grips. The present study was undertaken to generate hand anthropometric data of 95 women, working in informal industries (beedi, agarbatti and garment making). Fifty one hand measurements of the right hand (lengths, breadths, circumferences, depths, spreads and clearances of hand and fingers) were taken, using anthropometric sliding and spreading calipers, measuring tape and handgrip strength dynamometer. The data were statistically analyzed to determine the normality of data and the percentile values of different hand dimensions, and simple and multiple regression analysis were done to determine better predictors of hand length and grip strength. The hand breadths, circumferences and depths were approximately normally distributed, with some deviation in case of the finger lengths. Hand length was significantly correlated with the fist, wrist and finger circumferences. The fist and wrist circumferences, in combination, were better predictors of hand length. The hand lengths, breadths and depths, including finger joints of the Indian women studied were smaller than those of American, British and West Indian women. The hand circumferences of the Indian women were also smaller than the American women. Grip strengths of Indian women (20.36 +/- 3.24 kg) were less than those of American, British and West Indian women. Grip strength was found to be statistically significant with hand dimensions, such as hand height perpendicular to wrist crease (digit 5), proximal interphalangeal joint breadth (digit 3) and hand spread across wedge 1. The women who are forced to frequently use cutters, strippers and other tools, which are not optimally designed to their hand dimensions and strength range, might have higher prevalence of clinical symptoms and disorders of the hand. In view of the human hand-tool interface requirements, the present data on Indian women would be useful for ergo-design applications of hand tools and devices.

Small scale mechanical characterization of thin foil materials via pin load microtesting

DOE PAGES

Wheeler, Robert; Pandey, Amit; Shyam, Amit; ...

2015-05-06

In situ scanning electron microscope (SEM) experiments, where small-scale mechanical tests are conducted on micro- and nanosized specimens, allow direct visualization of elastic and plastic responses over the entirety of the volume being deformed. This enables precise spatial and temporal correlation of slip events contributing to the plastic flow evidenced in a stress–strain curve. A new pin-loading methodology has been employed, in situ within the SEM, to conduct microtensile tests on thin polycrystalline metal foils. This approach can be tailored to a specific foil whose particular grain size may range from microns to tens of microns. Manufacture of the specializedmore » pin grip was accomplished via silicon photolithography-based processing followed by subsequent focused ion beam finishing. Microtensile specimen preparation was achieved by combining a stencil mask methodology employing broad ion beam sputtering along with focused ion beam milling in the study of several metallic foil materials. Finite-element analyses were performed to characterize the stress and strain distributions in the pin grip and micro-specimen under load. Furthermore, under appropriately conceived test conditions, uniaxial stress–strain responses measured within these foils by pin-load microtensile testing exhibit properties consistent with larger scale tests.« less

Can short-term oral fine motor training affect precision of task performance and induce cortical plasticity of the jaw muscles?

PubMed

Zhang, Hong; Kumar, Abhishek; Kothari, Mohit; Luo, Xiaoping; Trulsson, Mats; Svensson, Krister G; Svensson, Peter

2016-07-01

The aim was to test the hypothesis that short-term oral sensorimotor training of the jaw muscles would increase the precision of task performance and induce neuroplastic changes in the corticomotor pathways, related to the masseter muscle. Fifteen healthy volunteers performed six series with ten trials of an oral sensorimotor task. The task was to manipulate and position a spherical chocolate candy in between the anterior teeth and split it into two equal halves. The precision of the task performance was evaluated by comparing the ratio between the two split halves. A series of "hold-and-split" tasks was also performed before and after the training. The hold force and split force along with the electromyographic (EMG) activity of jaw muscles were recorded. Motor-evoked potentials and cortical motor maps of the right masseter muscle were evoked by transcranial magnetic stimulation. There was a significant effect of series on the precision of the task performance during the short-term oral sensorimotor training (P < 0.002). The hold force during the "hold-and-split" task was significantly lower after training than before the short-term training (P = 0.011). However, there was no change in the split force and the EMG activity of the jaw muscles before and after the training. Further, there was a significant increase in the amplitude of the motor-evoked potentials (P < 0.016) and in the motor cortex map areas (P = 0.033), after the short-term oral sensorimotor training. Therefore, short-term oral sensorimotor task training increased the precision of task performance and induced signs of neuroplastic changes in the corticomotor pathways, related to the masseter muscle.

Ulnar digits contribution to grip strength in patients with thumb carpometacarpal osteoarthritis is less than in normal controls.

PubMed

Villafañe, Jorge H; Valdes, Kristin; Angulo-Diaz-Parreño, Santiago; Pillastrini, Paolo; Negrini, Stefano

2015-06-01

Grip testing is commonly used as an objective measure of strength in the hand and upper extremity and is frequently used clinically as a proxy measure of function. Increasing knowledge of hand biomechanics, muscle strength, and prehension patterns can provide us with a better understanding of the functional capabilities of the hand. The objectives of this study were to determine the contribution of ulnar digits to overall grip strength in individuals with thumb carpometacarpal (CMC) osteoarthritis (OA). Thirty-seven subjects participated in the study. This group consisted of 19 patients with CMC OA (aged 60-88 years) and 18 healthy subjects (60-88 years). Three hand configurations were used by the subjects during grip testing: use of the entire hand (index, middle, ring, and little fingers) (IMRL); use of the index, middle, and ring fingers (IMR); and use of only the index and middle fingers (IM). Grip strength findings for the two groups found that compared to their healthy counterparts, CMC OA patients had, on average, a strength deficiency of 45.6, 35.5, and 28.8 % in IMRL, IMR, and IM, respectively. The small finger contribution to grip is 14.3 % and the ring and small finger contribute 34 % in subjects with CMC OA. Grip strength decreases as the number of digits contributing decreased in both groups. The ulnar digits contribution to grip strength is greater than one third of total grip strength in subjects with CMC OA. Individuals with CMC OA demonstrate significantly decreased grip strength when compared to their healthy counterparts.

Grip strength and body composition in Turkana pastoralist children and adolescents.

PubMed

Little, Michael A

2017-03-01

In an earlier study, age changes and sex differences in grip strength were documented for adult Turkana pastoralists of Kenya (Little and Johnson, 1986). The objective here is to characterize age changes and sex differences in grip strength of Turkana children and adolescents in the context of arm lean tissue composition, and in comparison with other African, African-American, and non-Western populations. Anthropometric measurements, derived body composition values, and grip strength measures (maximum voluntary contraction) were taken on a sample of 232 nomadic Turkana pastoralist children (94 boys and 138 girls) aged 3 to 21 years. Relationships were tested between grip strength (in Newtons) and mid-upper arm (brachium) lean tissue cross-sectional areas. Comparisons were made among several different ethnic groups. Turkana children and adolescents had low arm muscle (derived lean tissue) and grip strength values when compared with U.S. NHANES percentile references. Girls' percentile rankings were greater than boys' percentile rankings for muscle and for grip strength. Both boys and girls were intermediate when compared with other non-Western populations and U.S. strength grip reference values. Correlations between grip strength and arm lean tissue areas were highly significant for both boys and girls. The greater relative muscle size and grip strength values of late adolescent girls compared to boys is consistent with an earlier study of adults. The difference is likely to result from greater physical subsistence activity and greater access to food in girls than in boys. Several suggestions are given to explain why Turkana youths have relatively small muscle sizes. © 2016 Wiley Periodicals, Inc.

Association between Race, Household Income and Grip Strength in Middle- and Older-Aged Adults.

PubMed

Thorpe, Roland J Jr; Simonsick, Eleanor; Zonderman, Alan; Evans, Michelle K

2016-10-20

Poor grip strength is an indicator of frailty and a precursor to functional limitations. Although poor grip strength is more prevalent in older disabled African American women, little is known about the association between race and poverty-related disparities and grip strength in middle-aged men and women. We examined the cross-sectional relationship between race, socioeconomic status as assessed by household income, and hand grip strength in men and women in the Healthy Aging in Neighborhoods of Diversity across the Life Span study. General linear models examined grip strength (maximum of two trials on both sides) by race and household income adjusted for age, weight, height, hand pain, education, insurance status, family income, and two or more chronic conditions. Of 2,091 adults, 422(45.4%) were male, 509(54.8%) were African American, and 320 (34.5%) were living in households with incomes below 125% of the federal poverty level (low SES). In adjusted models, African American women had greater grip strength than White women independent of SES (low income household: 29.3 vs 26.9 kg and high income household: 30.5 vs. 28.3kg; P<.05 for both); whereas in men, only African Americans in the high income household group had better grip strength than Whites (46.3 vs. 43.2; P<.05). The relationship between grip strength, race and SES as assessed by household income varied in this cohort. Efforts to develop grip strength norms and cut points that indicate frailty and sarcopenia may need to be race- and income-specific.

Comparison of grip and pinch strength in young women with and without hyperkyphosis: A cross-sectional study.

PubMed

Yoosefinejad, Amin Kordi; Ghaffarinejad, Farahnaz; Hemati, Mahbubeh; Jamshidi, Narges

2018-05-21

Hyperkyphosis is a common postural defect with high prevalence in the 20 to 50 year old population. It appears to compromise proximal scapular stability. Grip and pinch strength are used to evaluate general upper extremity function. The aim of this study was to compare pinch and grip strength between young women with and without hyperkyphosis. Thirty young women (18-40 years old) with hyperkyphosis and 30 healthy women matched for age and body mass index participated in the study. Hyperkyphosis was confirmed by measuring the kyphosis angle with a flexible ruler. Grip strength was measured with the Waisa method and a dynamometer. Pinch strength was assessed with a pinch meter. Grip (P= 0.03) and pinch strength (P= 0.04) were significantly lower in women with hyperkyphosis compared to the control group. Kyphosis angle correlated weakly with grip (r= 0.26) and pinch strength (r= 0.23). Hyperkyphotic posture has led to decreased grip and pinch strength compared to people without hyperkyphosis.

PICK1 interacts with ABP/GRIP to regulate AMPA receptor trafficking.

PubMed

Lu, Wei; Ziff, Edward B

2005-08-04

PICK1 and ABP/GRIP bind to the AMPA receptor (AMPAR) GluR2 subunit C terminus. Transfer of the receptor from ABP/GRIP to PICK1, facilitated by GluR2 S880 phosphorylation, may initiate receptor trafficking. Here we report protein interactions that regulate these steps. The PICK1 BAR domain interacts intermolecularly with the ABP/GRIP linker II region and intramolecularly with the PICK1 PDZ domain. Binding of PKCalpha or GluR2 to the PICK1 PDZ domain disrupts the intramolecular interaction and facilitates the PICK1 BAR domain association with ABP/GRIP. Interference with the PICK1-ABP/GRIP interaction impairs S880 phosphorylation of GluR2 by PKC and decreases the constitutive surface expression of GluR2, the NMDA-induced endocytosis of GluR2, and recycling of internalized GluR2. We suggest that the PICK1 interaction with ABP/GRIP is a critical step in controlling GluR2 trafficking.

Trigger Finger

MedlinePlus

... in a bent position. People whose work or hobbies require repetitive gripping actions are at higher risk ... developing trigger finger include: Repeated gripping. Occupations and hobbies that involve repetitive hand use and prolonged gripping ...

40Ar/ 39Ar, K-Ar and 230Th- 238U dating of the Laschamp excursion: A radioisotopic tie-point for ice core and climate chronologies

NASA Astrophysics Data System (ADS)

Singer, Brad S.; Guillou, Hervé; Jicha, Brian R.; Laj, Carlo; Kissel, Catherine; Beard, Brian L.; Johnson, Clark M.

2009-08-01

A brief period of enhanced 10Be flux that straddles the interstadial warm period known as Dansgaard-Oeschger event 10 in Greenland and its counterpart in Antarctica, the Antarctic Isotope Maximum 10 is but one consequence of the weakening of Earth's magnetic field associated with the Laschamp excursion. This 10Be peak measured in the GRIP ice core is dated at 41,250 y b2k (= before year 2000 AD) in the most recent GICC05 age model obtained from the NorthGRIP core via multi-parameter counting of annual layers. Uncertainty in the age of the 10Be peak is, however, no better than ± 1630 y at the 95% confidence level, reflecting accumulated error in identifying annual layers. The age of the Laschamp excursion [Guillou, H., Singer, B.S., Laj, C., Kissel, C., Scaillet, S., Jicha, B., 2004. On the age of the Laschamp geomagnetic excursion. Earth Planet. Sci. Lett. 227, 331-343.] is revised on the basis of new 40Ar/ 39Ar, unspiked K-Ar and 238U- 230Th data from three lava flows in the Massif Central, France, together with the 40Ar/ 39Ar age of a transitionally magnetized lava flow at Auckland, New Zealand. Combined, these data yield an age of 40,700 ± 950 y b2k, where the uncertainty includes both analytical and systematic ( 40K and 230Th decay constant) errors. Taking the radioisotopic age as a calibration tie point suggests that the layer-counting chronologies for the NorthGRIP and GISP2 ice cores are more accurate and precise than previously thought at depths corresponding to the Laschamp excursion.

White matter organization in cervical spinal cord relates differently to age and control of grip force in healthy subjects.

PubMed

Lindberg, Påvel G; Feydy, Antoine; Maier, Marc A

2010-03-17

Diffusion tensor imaging (DTI) can be used to elucidate relations between CNS structure and function. We hypothesized that the degree of spinal white matter organization relates to the accuracy of control of grip force. Healthy subjects of different age were studied using DTI and visuomotor tracking of precision grip force. The latter is a prime component of manual dexterity. A regional analysis of spinal white matter [fractional anisotropy (FA)] across multiple cervical levels (C2-C3, C4-C5, and C6-C7) and in different regions of interest (left and right lateral or medial spinal cord) was performed. FA was highest at the C2-C3 level, higher on the right than the left side, and higher in the lateral than in the medial spinal cord (p < 0.001). FA of whole cervical spinal cord (C2-C7) was lower in subjects with high tracking error (r = -0.56, p = 0.004) and decreased with age (r = -0.63, p = 0.001). A multiple regression analysis revealed an independent contribution of each predictor (semipartial correlations: age, r = -0.55, p < 0.001; tracking error, r = -0.49, p = 0.003). The closest relation between FA and tracking error was found at the C6-C7 level in the lateral spinal cord, in which the corticospinal tract innervates spinal circuitry controlling hand and digit muscles. FA of the medial spinal cord correlated consistently with age across all cervical levels, whereas FA of the lateral spinal cord did not. The results suggest (1) a functionally relevant specialization of lateral spinal cord white matter and (2) an increased sensitivity to age-related decline in medial spinal cord white matter in healthy subjects.

Effect of pre-task music on sports or exercise performance.

PubMed

Smirmaul, Bruno P

2017-01-01

Pre-task music is a very common strategy among sports competitors. However, as opposed to in-task music, the scientific evidence to support its ergogenic effects on either sports or exercise performance is limited. This brief review critically addresses the existing literature investigating the effects of pre-task music on sports and exercise performance, focusing on the methods and results of experimental studies, and offers basic and practical recommendations. In July 2015, a comprehensive literature search was performed in Web of Science, PubMed, and Google Scholar using the following key words in combination: "pre-task music," "pre-test music," "pre-exercise music," "exercise performance," "sports performance." The literature search was further expanded by both hand searching review articles on the topic and by searching the reference lists from the articles retrieved for any relevant references. Overall, a total of 15 studies in 14 articles were included. Pre-task music research has been unsystematic, methodologically limited and infrequent. Using this review as a starting point to overcome previous methodological limitations when designing future experiments may contribute to the development of pre-task music research, which is still in its infancy. Currently, there is no sufficient evidence to support the overall ergogenic effects of pre-task music on sports or exercise performance. Nonetheless, pre-task music has showed a likely ergogenic effect on shorter and predominantly anaerobic tasks such as grip strength, Wingate test, and short-duration sports or sports-like tasks, in contrast to longer and predominantly aerobic tasks.

Fixation Biases towards the Index Finger in Almost-Natural Grasping

PubMed Central

Voudouris, Dimitris; Smeets, Jeroen B. J.; Brenner, Eli

2016-01-01

We use visual information to guide our grasping movements. When grasping an object with a precision grip, the two digits need to reach two different positions more or less simultaneously, but the eyes can only be directed to one position at a time. Several studies that have examined eye movements in grasping have found that people tend to direct their gaze near where their index finger will contact the object. Here we aimed at better understanding why people do so by asking participants to lift an object off a horizontal surface. They were to grasp the object with a precision grip while movements of their hand, eye and head were recorded. We confirmed that people tend to look closer to positions that a digit needs to reach more accurately. Moreover, we show that where they look as they reach for the object depends on where they were looking before, presumably because they try to minimize the time during which the eyes are moving so fast that no new visual information is acquired. Most importantly, we confirmed that people have a bias to direct gaze towards the index finger’s contact point rather than towards that of the thumb. In our study, this cannot be explained by the index finger contacting the object before the thumb. Instead, it appears to be because the index finger moves to a position that is hidden behind the object that is grasped, probably making this the place at which one is most likely to encounter unexpected problems that would benefit from visual guidance. However, this cannot explain the bias that was found in previous studies, where neither contact point was hidden, so it cannot be the only explanation for the bias. PMID:26766551

Transfer of adaptation reveals shared mechanism in grasping and manual estimation.

PubMed

Cesanek, Evan; Domini, Fulvio

2018-06-19

An influential idea in cognitive neuroscience is that perception and action are highly separable brain functions, implemented in distinct neural systems. In particular, this theory predicts that the functional distinction between grasping, a skilled action, and manual estimation, a type of perceptual report, should be mirrored by a split between their respective control systems. This idea has received support from a variety of dissociations, yet many of these findings have been criticized for failing to pinpoint the source of the dissociation. In this study, we devised a novel approach to this question, first targeting specific grasp control mechanisms through visuomotor adaptation, then testing whether adapted mechanisms were also involved in manual estimation - a response widely characterized as perceptual in function. Participants grasped objects in virtual reality that could appear larger or smaller than the actual physical sizes felt at the end of each grasp. After brief exposure to a size perturbation, manual estimates were biased in the same direction as the maximum grip apertures of grasping movements, indicating that the adapted mechanism is active in both tasks, regardless of the perception-action distinction. Additional experiments showed that the transfer effect generalizes broadly over space (Exp. 1B) and does not appear to arise from a change in visual perception (Exp. 2). We discuss two adaptable mechanisms that could have mediated the observed effect: (a) an afferent proprioceptive mechanism for sensing grip shape; and (b) an efferent visuomotor transformation of size information into a grip-shaping motor command. Copyright © 2018. Published by Elsevier Ltd.

The influence of grasping habits and object orientation on motor planning in children and adults.

PubMed

Jovanovic, Bianca; Schwarzer, Gudrun

2017-12-01

We investigated the influence of habitual grasp strategies and object orientation on motor planning in 3-year-olds and 4- to 5-year-old children and adults. Participants were required to rotate different vertically oriented objects around 180°. Usually, adults perform this task by grasping objects with an awkward grip (thumb and index finger pointing downward) at the beginning of the movement, in order to finish it with a comfortable hand position. This pattern corresponds to the well-known end-state comfort effect (ESC) in grasp planning. The presented objects were associated with different habitual grasp orientations that either corresponded with the grasp direction required to reach end-state comfort (downward) or implied a contrary grasp orientation (upward). Additionally, they were presented either in their usual, canonical orientation (e.g., shovel with the blade oriented downward versus cup with its opening oriented upward) or upside down. As dependent variable we analyzed the number of grips conforming to the end-state comfort principle (ESC score) realized in each object type and orientation condition. The number of grips conforming to ESC strongly increased with age. In addition, the extent to which end-state comfort was considered was influenced by the actual orientation of the objects' functional parts. Thus, in all age-groups the ESC score was highest when the functional parts of the objects were oriented downward (shovel presented canonically with blade pointing downward, cup presented upside down) and corresponded to the hand orientation needed to realize ESC. © 2017 Wiley Periodicals, Inc.

Relationship between grip, pinch strengths and anthropometric variables, types of pitch throwing among Japanese high school baseball pitchers.

PubMed

Tajika, Tsuyoshi; Kobayashi, Tsutomu; Yamamoto, Atsushi; Shitara, Hitoshi; Ichinose, Tsuyoshi; Shimoyama, Daisuke; Okura, Chisa; Kanazawa, Saeko; Nagai, Ayako; Takagishi, Kenji

2015-03-01

Grip and pinch strength are crucially important attributes and standard parameters related to the functional integrity of the hand. It seems significant to investigate normative data for grip and pinch strength of baseball players to evaluate their performance and condition. Nevertheless, few reports have explained the association between grip and pinch strength and anthropometric variables and types of pitch throwing for baseball pitchers. The aim of this study was to measure and evaluate clinical normative data for grip and tip, key, palmar pinch strength and to assess the relationship between these data and anthropometric variables and types of pitch throwing among Japanese high-school baseball pitchers. One hundred-thirty three healthy high school baseball pitchers were examined and had completed a self-administered questionnaire including items related to age, hand dominance, throwing ratio of type of pitch. A digital dynamometer was used to measure grip strength and a pinch gauge to measure tip, key and palmer pinch in both dominant and nondominant side. Body composition was measured by the multi frequency segmental body composition analyzer. Grip strength and tip and palmer pinch strength in dominant side were statistically greater than them in nondominant side (P < 0.05). There were significant associations between grip strength and height (r = 0.33, P < 0.001), body mass (r = 0.50, P < 0.001), BMI (r = 0.37, P < 0.001), muscle mass of upper extremity (r = 0.56, P < 0.001), fat free mass (r = 0.57, P < 0.001), fat mass (r = 0.22, P < 0.05) in dominant side. A stepwise multiple regression analysis revealed that fat free mass and tip, palmer, key pinch strength were predictors of grip strength in dominant side. No statistical significant correlations were found between the throwing ratio of types of pitches thrown and grip strength and tip, key, palmar pinch strength. Our result provides normative values and evidences for grip and pinch strengths in high school baseball pitchers.

Measuring Grip Pressure during the Golf Swing.

ERIC Educational Resources Information Center

Budney, David R.

1979-01-01

With the use of a special instrumented golf club, grip pressure measurements can be used by the instructor to quantify and discuss the effects of grip pressure in relation to instructional points. (MM)

Template optimization and transfer in perceptual learning.

PubMed

Kurki, Ilmari; Hyvärinen, Aapo; Saarinen, Jussi

2016-08-01

We studied how learning changes the processing of a low-level Gabor stimulus, using a classification-image method (psychophysical reverse correlation) and a task where observers discriminated between slight differences in the phase (relative alignment) of a target Gabor in visual noise. The method estimates the internal "template" that describes how the visual system weights the input information for decisions. One popular idea has been that learning makes the template more like an ideal Bayesian weighting; however, the evidence has been indirect. We used a new regression technique to directly estimate the template weight change and to test whether the direction of reweighting is significantly different from an optimal learning strategy. The subjects trained the task for six daily sessions, and we tested the transfer of training to a target in an orthogonal orientation. Strong learning and partial transfer were observed. We tested whether task precision (difficulty) had an effect on template change and transfer: Observers trained in either a high-precision (small, 60° phase difference) or a low-precision task (180°). Task precision did not have an effect on the amount of template change or transfer, suggesting that task precision per se does not determine whether learning generalizes. Classification images show that training made observers use more task-relevant features and unlearn some irrelevant features. The transfer templates resembled partially optimized versions of templates in training sessions. The template change direction resembles ideal learning significantly but not completely. The amount of template change was highly correlated with the amount of learning.

Representational momentum in perception and grasping: translating versus transforming objects.

PubMed

Brouwer, Anne-Marie; Franz, Volker H; Thornton, Ian M

2004-07-14

Representational momentum is the tendency to misremember the stopping point of a moving object as further forward in the direction of movement. Results of several studies suggest that this effect is typical for changes in position (e.g., translation) and not for changes in object shape (transformation). Additionally, the effect seems to be stronger in motor tasks than in perceptual tasks. Here, participants judged the final distance between two spheres after this distance had been increasing or decreasing. The spheres were two separately translating objects or were connected to form a single transforming object (a dumbbell). Participants also performed a motor task in which they grasped virtual versions of the final objects. We found representational momentum for the visual judgment task for both stimulus types. As predicted, it was stronger for the spheres than for the dumbbells. In contrast, for grasping, only the dumbbells produced representational momentum (larger maximum grip aperture when the dumbbells had been growing compared to when they had been shrinking). Because type of stimulus change had these different effects on representational momentum for perception and action, we conclude that different sources of information are used in the two tasks or that they are governed by different mechanisms.

The relationship between general measures of fitness, passive range of motion and whole-body movement quality.

PubMed

Frost, David; Andersen, Jordan; Lam, Thomas; Finlay, Tim; Darby, Kevin; McGill, Stuart

2013-01-01

The goal of this study was to establish relationships between fitness (torso endurance, grip strength and pull-ups), hip range of motion (ROM) (extension, flexion, internal and external rotation) and movement quality in an occupational group with physical work demands. Fifty-three men from the emergency task force of a major city police force were investigated. The movement screen comprised standing and seated posture, gait, segmental spine motion and 14 tasks designed to challenge whole-body coordination. Relationships were established between each whole-body movement task, the measures of strength, endurance and ROM. In general, fitness and ROM were not strongly related to the movement quality of any task. This has implications for worker training, in that strategies developed to improve ROM or strength about a joint may not enhance movement quality. Worker-centered injury prevention can be described as fitting workers to tasks by improving fitness and modifying movement patterns; however, the current results show weak correlations between strength, endurance and ROM, and the way individuals move. Therefore, the development of occupation-specific injury prevention strategies may require both fitness and movement-oriented objectives.

Systems and Methods for Gravity-Independent Gripping and Drilling

NASA Technical Reports Server (NTRS)

Thatte, Nitish (Inventor); King, Jonathan P. (Inventor); Parness, Aaron (Inventor); Frost, Matthew A. (Inventor)

2016-01-01

Systems and methods for gravity independent gripping and drilling are described. The gripping device can also comprise a drill or sampling devices for drilling and/or sampling in microgravity environments, or on vertical or inverted surfaces in environments where gravity is present. A robotic system can be connected with the gripping and drilling devices via an ankle interface adapted to distribute the forces realized from the robotic system.

Hand grip strength and associated factors in non-institutionalised men and women 50 years and older in South Africa.

PubMed

Ramlagan, Shandir; Peltzer, Karl; Phaswana-Mafuya, Nancy

2014-01-07

Little is known about the prevalence, predictors and gender differences in hand grip strength of older adults in Africa. This study aims to investigate social and health differences in hand grip strength among older adults in a national probability sample of older South Africans who participated in the Study of Global Ageing and Adults Health (SAGE wave 1) in 2008. We conducted a national population-based cross-sectional study with a sample of 3840 men and women aged 50 years or older in South Africa. The questionnaire included socio-demographic characteristics, health variables, and anthropometric measurements. Linear multivariate regression analysis was performed to assess the association of social factors, health variables and grip strength. The mean overall hand grip strength was 37.9 kgs for men (mean age 61.1 years, SD = 9.1) and 31.5 kgs for women (mean age 62.0 years, SD = 9.7). In multivariate analysis among men, greater height, not being underweight and lower functional disability was associated with greater grip strength, and among women, greater height, better cognitive functioning, and lower functional disability were associated with greater grip strength. Greater height and lower functional disability were found for both older South African men and women to be significantly associated with grip strength.

Using Hand Grip Force as a Correlate of Longitudinal Acceleration Comfort for Rapid Transit Trains

PubMed Central

Guo, Beiyuan; Gan, Weide; Fang, Weining

2015-01-01

Longitudinal acceleration comfort is one of the essential metrics used to evaluate the ride comfort of train. The aim of this study was to investigate the effectiveness of using hand grip force as a correlate of longitudinal acceleration comfort of rapid transit trains. In the paper, a motion simulation system was set up and a two-stage experiment was designed to investigate the role of the grip force on the longitudinal comfort of rapid transit trains. The results of the experiment show that the incremental grip force was linearly correlated with the longitudinal acceleration value, while the incremental grip force had no correlation with the direction of the longitudinal acceleration vector. The results also show that the effects of incremental grip force and acceleration duration on the longitudinal comfort of rapid transit trains were significant. Based on multiple regression analysis, a step function model was established to predict the longitudinal comfort of rapid transit trains using the incremental grip force and the acceleration duration. The feasibility and practicably of the model was verified by a field test. Furthermore, a comparative analysis shows that the motion simulation system and the grip force based model were valid to support the laboratory studies on the longitudinal comfort of rapid transit trains. PMID:26147730

Changing the precision of preschoolers' approximate number system representations changes their symbolic math performance.

PubMed

Wang, Jinjing Jenny; Odic, Darko; Halberda, Justin; Feigenson, Lisa

2016-07-01

From early in life, humans have access to an approximate number system (ANS) that supports an intuitive sense of numerical quantity. Previous work in both children and adults suggests that individual differences in the precision of ANS representations correlate with symbolic math performance. However, this work has been almost entirely correlational in nature. Here we tested for a causal link between ANS precision and symbolic math performance by asking whether a temporary modulation of ANS precision changes symbolic math performance. First, we replicated a recent finding that 5-year-old children make more precise ANS discriminations when starting with easier trials and gradually progressing to harder ones, compared with the reverse. Next, we show that this brief modulation of ANS precision influenced children's performance on a subsequent symbolic math task but not a vocabulary task. In a supplemental experiment, we present evidence that children who performed ANS discriminations in a random trial order showed intermediate performance on both the ANS task and the symbolic math task, compared with children who made ordered discriminations. Thus, our results point to a specific causal link from the ANS to symbolic math performance. Copyright © 2016 Elsevier Inc. All rights reserved.

Changing the precision of preschoolers’ approximate number system representations changes their symbolic math performance

PubMed Central

Wang, Jinjing (Jenny); Odic, Darko; Halberda, Justin; Feigenson, Lisa

2016-01-01

From early in life, humans have access to an Approximate Number System (ANS) that supports an intuitive sense of numerical quantity. Previous work in both children and adults suggests that individual differences in the precision of ANS representations correlate with symbolic math performance. However, this work has been almost entirely correlational in nature. Here we tested for a causal link between ANS precision and symbolic math performance by asking whether a temporary modulation of ANS precision changes symbolic math performance. First we replicated a recent finding that 5-year-old children make more precise ANS discriminations when starting with easier trials and gradually progressing to harder ones, compared to the reverse. Next, we show that this brief modulation of ANS precision influenced children’s performance on a subsequent symbolic math task, but not a vocabulary task. In a supplemental experiment we present evidence that children who performed ANS discriminations in a random trial order showed intermediate performance both on the ANS task and the symbolic math task, compared to the children who made ordered discriminations. Thus, our results point to a specific causal link from the ANS to symbolic math performance. PMID:27061668

Control of finger forces during fast, slow and moderate rotational hand movements.

PubMed

Kazemi, Hamed; Kearney, Robert E; Milner, Theodore E

2014-01-01

The goal of this study was to investigate the effect of speed on patterns of grip forces during twisting movement involving forearm supination against a torsional load (combined elastic and inertial load). For slow and moderate speed rotations, the grip force increased linearly with load torque. However, for fast rotations in which the contribution of the inertia to load torque was significantly greater than slower movements, the grip force-load torque relationship could be segmented into two phases: a linear ascending phase corresponding to the acceleration part of the movement followed by a plateau during deceleration. That is, during the acceleration phase, the grip force accurately tracked the combined elastic and inertial load. However, the coupling between grip force and load torque was not consistent during the deceleration phase of the movement. In addition, as speed increased, both the position and the force profiles became smoother. No differences in the baseline grip force, safety margin to secure the grasp during hold phase or the overall change in grip force were observed across different speeds.

Integration of a computerized two-finger gripper for robot workstation safety

NASA Technical Reports Server (NTRS)

Sneckenberger, John E.; Yoshikata, Kazuki

1988-01-01

A microprocessor-based controller has been developed that continuously monitors and adjusts the gripping force applied by a special two-finger gripper. This computerized force sensing gripper system enables the endeffector gripping action to be independently detected and corrected. The gripping force applied to a manipulated object is real-time monitored for problem situations, situations which can occur during both planned and errant robot arm manipulation. When unspecified force conditions occur at the gripper, the gripping force controller initiates specific reactions to cause dynamic corrections to the continuously variable gripping action. The force controller for this intelligent gripper has been interfaced to the controller of an industrial robot. The gripper and robot controllers communicate to accomplish the successful completion of normal gripper operations as well as unexpected hazardous situations. An example of an unexpected gripping condition would be the sudden deformation of the object being manipulated by the robot. The capabilities of the interfaced gripper-robot system to apply workstation safety measures (e.g., stop the robot) when these unexpected gripping effects occur have been assessed.

Effects of EVA gloves on grip strength and fatigue under low temperature and low pressure.

PubMed

Tian, Yinsheng; Ding, Li; Liu, Heqing; Li, Yan; Li, Deyu; Wang, Li

2016-03-01

To study the effects of wearing extravehicular activity (EVA) gloves on grip strength and fatigue in low temperature, low pressure and mixing of two factors (low temperature and low pressure). The maximum grip strength and fatigue tests were performed with 10 healthy male subjects wearing gloves in a variety of simulated environments. The data was analysed using the normalization method. The results showed that wearing gloves significantly affected the maximum grip strength and fatigue. Pressure (29.6, 39.2 kPa) had more influence on the maximum grip compared with control group while low temperatures (-50, -90, -110 °C) had no influence on grip but affected fatigue dramatically. The results also showed that the maximum grip strength and fatigue were influenced significantly in a compound environment. Space environment remarkably reduced strength and endurance of the astronauts. However, the effects brought by the compound environment cannot be understood as the superimposition of low temperature and pressure effects. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Motor development in individuals with congenital adrenal hyperplasia: strength, targeting, and fine motor skill.

PubMed

Collaer, Marcia L; Brook, Charles G D; Conway, Gerard S; Hindmarsh, Peter C; Hines, Melissa

2009-02-01

This study investigated early androgen influence on the development of human motor and visuomotor characteristics. Participants, ages 12-45 years, were individuals with congenital adrenal hyperplasia (CAH), a disorder causing increased adrenal androgen production before birth (40 females, 29 males) and their unaffected relatives (29 females, 30 males). We investigated grip strength and visuomotor targeting tasks on which males generally outperform females, and fine motor pegboard tasks on which females generally outperform males. Physical characteristics (height and weight) were measured to explore whether body parameters could explain differences in motor skills. Females with CAH were stronger and showed better targeting than unaffected females and showed reduced fine visuomotor skill on one pegboard measure, with no difference on the other. Males with CAH were weaker than unaffected males in grip strength but did not differ on the targeting or pegboard measures. Correction for body size could not explain the findings for females, but suggests that the reduced strength of males with CAH may relate to their smaller stature. Further, the targeting advantage in females with CAH persisted following adjustment for their greater strength. Results in females support the hypothesis that androgen may masculinize, or promote, certain motor characteristics at which males excel, and contribute to defeminization of certain fine motor characteristics at which females excel. Thus, these data suggest that organizational effects of androgens on behavior during prenatal life may extend to motor characteristics and may contribute to general sex differences in motor-related behaviors; however, alternative explanations based on activational influences of androgen or altered experiential factors cannot be excluded without further study.

Exogrip: assisted hand strength glove - biomed 2011.

PubMed

Best, Jade E; Bostick, Nehemiah F; Connelly, John R; Dunn, Michael G; Gelles, Richard A; Norvell, Elizabeth K; Waugaman, William B; Mims, Capt Willie H

2011-01-01

A large number of American troops fighting in Afghanistan and Iraq have received wounds in their upper extremities leading to significant nerve damage and loss of strength. These injuries impair their ability to perform day-to-day tasks such as lifting a cup of coffee or opening a door. Although the cause of some injuries in service-people is often unique to their employment, civilian employees in other industries are also plagued with similar physical damage due to other kinds of injuries. Our goal is to develop a device to augment the strength of injured troops and civilian workers so they can perform everyday tasks despite their physical limitations. The ExoGrip is a glove designed to provide this necessary strength augmentation. The ExoGrip consists primarily of pressure sensors, linear actuators, and a microcontroller to provide a force multiplier based on a person’s strength. The goal of the first phase of the project was to conduct research and also produce a working prototype of one finger. This goal was achieved by a group of classmates who started the project a year before. Their research and feasibility analysis ended in the mechanical movement of a single finger when the sensors were activated. The next phase of this project is to design and integrate a working prototype that manipulates all four fingers, while keeping the thumb in a fixed position. This paper describes the integration of new microcontrollers, linear actuators utilizing pulse width modulation technology, and improved pressure sensors needed to manipulate the fingers, as well as laying the foundation for future testing and development of a final product.

23. POWELLTYPE CAR THROUGH GRIP REMOVAL DOOR: View looking through ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. POWELL-TYPE CAR THROUGH GRIP REMOVAL DOOR: View looking through grip removal door into interior of a Powell-type cable car. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA

GRIPPING DEVICE FOR CYLINDRICAL OBJECTS

DOEpatents

Pilger, J.P.

1964-01-21

A gripping device is designed for fragile cylindrical objects such as for drawing thin-walled tubes. The gripping is done by multiple jaw members held in position by two sets of slots, one defined by keystone-shaped extensions of the outer shell of the device and the other in a movable sleeve held slidably by the extensions. Forward movement oi the sleeve advances the jaws, thereby exerting a controlled, radial pressure on the object being gripped. (AEC)

Alterations in grip strength during male sexual arousal.

PubMed

Jiao, C; Turman, B; Weerakoon, P; Knight, P

2006-01-01

Although it is known that alterations in grip strength occur under a number of conditions, little is known about relationships between grip strength and sexual arousal. This relationship was investigated in 30 healthy heterosexual males, who viewed both erotic and nonerotic videos. A questionnaire was used to assess the extent of sexual arousal. The grip strengths of both hands were measured with a five-position (P1-P5) dynamometer, before and after watching the videos. After watching the erotic video, there was a statistically significant reduction in grip strength for the P2 position, with nonsignificant overall reductions in grip strength for all other positions tested. No such effect was observed in control tests. The results indicate that during sexual arousal, the neural system is likely to reduce the output to muscles not directly related to sexual function, presumably to enhance the physiological responses of sexual arousal.

Laboratory or Field Tests for Evaluating Firefighters' Work Capacity?

PubMed Central

Lindberg, Ann-Sofie; Oksa, Juha; Malm, Christer

2014-01-01

Muscle strength is important for firefighters work capacity. Laboratory tests used for measurements of muscle strength, however, are complicated, expensive and time consuming. The aims of the present study were to investigate correlations between physical capacity within commonly occurring and physically demanding firefighting work tasks and both laboratory and field tests in full time (N = 8) and part-time (N = 10) male firefighters and civilian men (N = 8) and women (N = 12), and also to give recommendations as to which field tests might be useful for evaluating firefighters' physical work capacity. Laboratory tests of isokinetic maximal (IM) and endurance (IE) muscle power and dynamic balance, field tests including maximal and endurance muscle performance, and simulated firefighting work tasks were performed. Correlations with work capacity were analyzed with Spearman's rank correlation coefficient (rs). The highest significant (p<0.01) correlations with laboratory and field tests were for Cutting: IE trunk extension (rs = 0.72) and maximal hand grip strength (rs = 0.67), for Stairs: IE shoulder flexion (rs = −0.81) and barbell shoulder press (rs = −0.77), for Pulling: IE shoulder extension (rs = −0.82) and bench press (rs = −0.85), for Demolition: IE knee extension (rs = 0.75) and bench press (rs = 0.83), for Rescue: IE shoulder flexion (rs = −0.83) and bench press (rs = −0.82), and for the Terrain work task: IE trunk flexion (rs = −0.58) and upright barbell row (rs = −0.70). In conclusion, field tests may be used instead of laboratory tests. Maximal hand grip strength, bench press, chin ups, dips, upright barbell row, standing broad jump, and barbell shoulder press were strongly correlated (rs≥0.7) with work capacity and are therefore recommended for evaluating firefighters work capacity. PMID:24614596

Implementation and performance evaluation open-source controller for precision control of gripper

NASA Astrophysics Data System (ADS)

Lee, Seung-Yong; Ham, Un-Hyeong; Park, Young-Woo; Jung, Hak-Sang; Jung, Il-Kyun; Lim, Sun

2017-12-01

This paper proposes integrating gripper embedded operating system, which consist of external interface structure for sophisticated gripper control. This system has multiple functions that control the gripping module and measure the pose of the gripper body with respect to contact environment. A controller based on open source only for the gripper is developed and an external communication interface between robot controller and gripper controller is designed. An experimental environment for the fixed-cycle test consists of integrating magic gripper software system and hardware on commercial business. As a result, a deviation is measured approximately 2% and the system were verified for gripper control.

Soft Robotic Manipulation and Locomotion with a 3D Printed Electroactive Hydrogel.

PubMed

Han, Daehoon; Farino, Cindy; Yang, Chen; Scott, Tracy; Browe, Daniel; Choi, Wonjoon; Freeman, Joseph W; Lee, Howon

2018-05-30

Electroactive hydrogels (EAH) that exhibit large deformation in response to an electric field have received great attention as a potential actuating material for soft robots and artificial muscle. However, their application has been limited due to the use of traditional two-dimensional (2D) fabrication methods. Here we present soft robotic manipulation and locomotion with 3D printed EAH microstructures. Through 3D design and precise dimensional control enabled by a digital light processing (DLP) based micro 3D printing technique, complex 3D actuations of EAH are achieved. We demonstrate soft robotic actuations including gripping and transporting an object and a bidirectional locomotion.

Nutritional status is the major factor affecting grip strength of African HIV patients before and during antiretroviral treatment.

PubMed

Filteau, S; PrayGod, G; Woodd, S L; Friis, H; Heimburger, D C; Koethe, J R; Kelly, P; Kasonka, L; Rehman, A M

2017-10-01

Low grip strength is a marker of frailty and a risk factor for mortality among HIV patients and other populations. We investigated factors associated with grip strength in malnourished HIV patients at referral to ART, and at 12 weeks and 2-3 years after starting ART. The study involved HIV-infected Zambian and Tanzanian participants recruited to the NUSTART trial when malnourished (body mass index <18.5 kg/m 2 ) and requiring ART. The relationship of grip strength to nutritional, infectious and demographic factors was assessed by multivariable linear regression at referral for ART (n = 1742) and after 12 weeks (n = 778) and 2-3 years of ART (n = 273). In analyses controlled only for sex, age and height, most nutrition and infection-related variables were associated with grip strength. However, in multivariable analyses, consistent associations were seen for fat-free mass index, mid-upper arm circumference, haemoglobin and systolic blood pressure, and a variable association with fat mass index in men. C-reactive protein and CD4 count had limited independent effects on grip strength, while receiving tuberculosis treatment was associated with weaker grip strength. In this population of originally malnourished HIV patients, poor grip strength was more strongly and independently associated with nutritional than with infection and inflammation variables. Programmes to improve health and survival of HIV patients should incorporate nutritional assessment and management and could use grip strength as a functional indicator of improving nutrition. © 2017 John Wiley & Sons Ltd.

The Association of Levels of and Decline in Grip Strength in Old Age with Trajectories of Life Course Occupational Position.

PubMed

Kröger, Hannes; Fritzell, Johan; Hoffmann, Rasmus

2016-01-01

The study of the influence of life course occupational position (OP) on health in old age demands analysis of time patterns in both OP and health. We study associations between life course time patterns of OP and decline in grip strength in old age. We analyze 5 waves from the Survey of Health Ageing and Retirement in Europe (n = 5108, ages 65-90). We use a pattern-mixture latent growth model to predict the level and decline in grip strength in old age by trajectory of life course OP. We extend and generalize the structured regression approach to establish the explanatory power of different life course models for both the level and decline of grip strength. Grip strength declined linearly by 0.70 kg (95% CI -0.74;-0.66) for men and 0.42 kg (95% CI -0.45;-0.39) for women per year. The level of men's grip strength can best be explained by a critical period during midlife, with those exposed to low OP during this period having 1.67 kg (95% CI -2.33;-1.00) less grip strength. These differences remain constant over age. For women, no association between OP and levels of or decline in grip strength was found. Men's OP in midlife seems to be a critical period for the level of grip strength in old age. Inequalities remain constant over age. The integration of the structured regression approach and latent growth modelling offers new possibilities for life course epidemiology.

Factors associated with grip strength decline in older adults.

PubMed

Sternäng, Ola; Reynolds, Chandra A; Finkel, Deborah; Ernsth-Bravell, Marie; Pedersen, Nancy L; Dahl Aslan, Anna K

2015-03-01

Few studies have examined associations of multi-faceted demographic, health and lifestyle factors with long-term change in grip strength performance across the adult lifespan. The aim of this study was to examine the associations of risk factors in specific parts of the adult lifespan (e.g. in early midlife, in late midlife and in old adulthood) separately for women and men. Data came from the longitudinal Swedish Adoption/Twin Study of Aging (SATSA). Grip strength performance was followed in 849 participants who were 50-88 years of age at baseline. The follow-up period with seven waves of data of grip strength was 22 years, and the risk factors were measured up to 20 years before the assessment of grip strength. Latent growth modelling was used for the longitudinal analyses. A gender difference in the type of factors associated with grip strength performance and development across the adult lifespan was found. Significant factors for the age slopes for women were stress, smoking and dementia. For men, marital status, mean arterial pressure, physical activity at work and having a chronic disorder were of importance. These factors varied in their associations with grip strength across the adult lifespan. Factors measured earlier in adulthood were associated with grip strength decline in late midlife and old adulthood. Gender-specific patterns of risk factors suggest that it may be worthwhile to conduct research on grip and muscle strength (and biological vitality) separately for men and women. © The Author 2014. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Hand grip strength and associated factors in non-institutionalised men and women 50 years and older in South Africa

PubMed Central

2014-01-01

Background Little is known about the prevalence, predictors and gender differences in hand grip strength of older adults in Africa. This study aims to investigate social and health differences in hand grip strength among older adults in a national probability sample of older South Africans who participated in the Study of Global Ageing and Adults Health (SAGE wave 1) in 2008. Methods We conducted a national population-based cross-sectional study with a sample of 3840 men and women aged 50 years or older in South Africa. The questionnaire included socio-demographic characteristics, health variables, and anthropometric measurements. Linear multivariate regression analysis was performed to assess the association of social factors, health variables and grip strength. Results The mean overall hand grip strength was 37.9 kgs for men (mean age 61.1 years, SD = 9.1) and 31.5 kgs for women (mean age 62.0 years, SD = 9.7). In multivariate analysis among men, greater height, not being underweight and lower functional disability was associated with greater grip strength, and among women, greater height, better cognitive functioning, and lower functional disability were associated with greater grip strength. Conclusions Greater height and lower functional disability were found for both older South African men and women to be significantly associated with grip strength. PMID:24393403

Age-related normative values for handgrip strength and grip strength’s usefulness as a predictor of mortality and both cognitive and physical decline in older adults in northwest Russia

PubMed Central

Turusheva, A.; Frolova, E.; Degryse, J-M.

2017-01-01

Objectives: This paper sought to provide normative values for grip strength among older adults across different age groups in northwest Russia and to investigate their predictive value for adverse events. Methods: A population-based prospective cohort study of 611 community-dwelling individuals 65+. Grip strength was measured using the standard protocol applied in the Groningen Elderly Tests. The cut-off thresholds for grip strength were defined separately for men and women of different ages using a weighted polynomial regression. A Cox regression analysis, the c-statistic, a risk reclassification analysis, and bootstrapping techniques were used to analyze the data. The outcomes were the 5-year mortality rate, the loss of autonomy and mental decline. Results: We determined the age-related reference intervals of grip strength for older adults. The 5th and 10th percentiles of grip strength were associated with a higher risk for malnutrition, low autonomy, physical and mental functioning and 5-year mortality. The 5th percentile of grip strength was associated with a decline in autonomy. Conclusions: This study presents age- and sex-specific reference values for grip strength in the 65+ Russian population derived from a prospective cohort study. The norms can be used in clinical practice to identify patients at increased risk for adverse outcomes. PMID:28250246

Exploring the Relationship of Task Performance and Physical and Cognitive Fatigue During a Daylong Light Precision Task.

PubMed

Yung, Marcus; Manji, Rahim; Wells, Richard P

2017-11-01

Our aim was to explore the relationship between fatigue and operation system performance during a simulated light precision task over an 8-hr period using a battery of physical (central and peripheral) and cognitive measures. Fatigue may play an important role in the relationship between poor ergonomics and deficits in quality and productivity. However, well-controlled laboratory studies in this area have several limitations, including the lack of work relevance of fatigue exposures and lack of both physical and cognitive measures. There remains a need to understand the relationship between physical and cognitive fatigue and task performance at exposure levels relevant to realistic production or light precision work. Errors and fatigue measures were tracked over the course of a micropipetting task. Fatigue responses from 10 measures and errors in pipetting technique, precision, and targeting were submitted to principal component analysis to descriptively analyze features and patterns. Fatigue responses and error rates contributed to three principal components (PCs), accounting for 50.9% of total variance. Fatigue responses grouped within the three PCs reflected central and peripheral upper extremity fatigue, postural sway, and changes in oculomotor behavior. In an 8-hr light precision task, error rates shared similar patterns to both physical and cognitive fatigue responses, and/or increases in arousal level. The findings provide insight toward the relationship between fatigue and operation system performance (e.g., errors). This study contributes to a body of literature documenting task errors and fatigue, reflecting physical (both central and peripheral) and cognitive processes.

Hand grip strength and dexterity function in children aged 6-12 years: A cross-sectional study.

PubMed

Omar, Mohammed T A; Alghadir, Ahmad H; Zafar, Hamayun; Al Baker, Shaheerah

Cross-sectional and clinical measurement. Assessment of hand function considers an essential part in clinical practice. To develop normative values of hand grip strength and dexterity function for 6-12-year-old children in Saudi Arabia. Grip strength and dexterity function was measured in 525 children using Grip Track hand dynamometer (JTECH Medical, Midvale, UT, USA) and 9-hole pegboard test respectively. The grip strength and dexterity function was improved as age progressed regardless of gender. Across all age groups, the hand grip strength of boys was significantly higher than girls for dominant hand (31.75 ± 10.33 vs 28.24 ± 9.35; P < .001) and nondominant hand (31.01 ± 10.27 vs 27.27 ± 9.30; P < .001). The girls performed slightly faster than boys for dominant hand (19.70 vs 20.68; P < .05) and nondominant hand (21.79 vs 23.46; P < .05). In general, girls completed a 9-HPT faster than boys in the 2 of 7 age groups: 11 years (9-HPT scores = 2.10 seconds; P < .01) and 12 years (9-HPT scores = 1.93 seconds; P < .01). The overall patterns of hand grip strength and dexterity function observed in the present study are similar to the previous studies that established acceleration of grip strength with advanced age, and faster performance scores in older children than younger children in both genders. Norms of hand grip strength and dexterity enable therapists to identify some developmental characteristics of hand function among Saudi children, determine the presence of impairment, and compare scores from children in different clinical settings. Not applicable. Copyright © 2017 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

On the development of a computer-based handwriting assessment tool to objectively quantify handwriting proficiency in children.

PubMed

Falk, Tiago H; Tam, Cynthia; Schellnus, Heidi; Chau, Tom

2011-12-01

Standardized writing assessments such as the Minnesota Handwriting Assessment (MHA) can inform interventions for handwriting difficulties, which are prevalent among school-aged children. However, these tests usually involve the laborious task of subjectively rating the legibility of the written product, precluding their practical use in some clinical and educational settings. This study describes a portable computer-based handwriting assessment tool to objectively measure MHA quality scores and to detect handwriting difficulties in children. Several measures are proposed based on spatial, temporal, and grip force measurements obtained from a custom-built handwriting instrument. Thirty-five first and second grade students participated in the study, nine of whom exhibited handwriting difficulties. Students performed the MHA test and were subjectively scored based on speed and handwriting quality using five primitives: legibility, form, alignment, size, and space. Several spatial parameters are shown to correlate significantly (p<0.001) with subjective scores obtained for alignment, size, space, and form. Grip force and temporal measures, in turn, serve as useful indicators of handwriting legibility and speed, respectively. Using only size and space parameters, promising discrimination between proficient and non-proficient handwriting can be achieved. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Proximal forearm extensor muscle strain is reduced when driving nails using a shock-controlled hammer.

PubMed

Buchanan, Kimberly A; Maza, Maria; Pérez-Vázquez, Carlos E; Yen, Thomas Y; Kijowski, Richard; Liu, Fang; Radwin, Robert G

2016-10-01

Repetitive hammer use has been associated with strain and musculoskeletal injuries. This study investigated if using a shock-control hammer reduces forearm muscle strain by observing adverse physiological responses (i.e. inflammation and localized edema) after use. Three matched framing hammers were studied, including a wood-handle, steel-handle, and shock-control hammer. Fifty volunteers were randomly assigned to use one of these hammers at a fatiguing pace of one strike every second, to seat 20 nails in a wood beam. Magnetic resonance imaging was used to scan the forearm muscles for inflammation before the task, immediately after hammering, and one to two days after. Electromyogram signals were measured to estimate grip exertions and localized muscle fatigue. High-speed video was used to calculate the energy of nail strikes. While estimated grip force was similar across the three hammers, the shock-control hammer had 40% greater kinetic energy upon impact and markedly less proximal extensor muscle edema than the wood-handle and steel-handle hammers, immediately after use (p<.05). Less edema observed for the shock-control hammer suggests that isolating handle shock can mitigate strain in proximal forearm extensor muscles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Intention Understanding in Autism

PubMed Central

Boria, Sonia; Fabbri-Destro, Maddalena; Cattaneo, Luigi; Sparaci, Laura; Sinigaglia, Corrado; Santelli, Erica; Cossu, Giuseppe; Rizzolatti, Giacomo

2009-01-01

When we observe a motor act (e.g. grasping a cup) done by another individual, we extract, according to how the motor act is performed and its context, two types of information: the goal (grasping) and the intention underlying it (e.g. grasping for drinking). Here we examined whether children with autistic spectrum disorder (ASD) are able to understand these two aspects of motor acts. Two experiments were carried out. In the first, one group of high-functioning children with ASD and one of typically developing (TD) children were presented with pictures showing hand-object interactions and asked what the individual was doing and why. In half of the “why” trials the observed grip was congruent with the function of the object (“why-use” trials), in the other half it corresponded to the grip typically used to move that object (“why-place” trials). The results showed that children with ASD have no difficulties in reporting the goals of individual motor acts. In contrast they made several errors in the why task with all errors occurring in the “why-place” trials. In the second experiment the same two groups of children saw pictures showing a hand-grip congruent with the object use, but within a context suggesting either the use of the object or its placement into a container. Here children with ASD performed as TD children, correctly indicating the agent's intention. In conclusion, our data show that understanding others' intentions can occur in two ways: by relying on motor information derived from the hand-object interaction, and by using functional information derived from the object's standard use. Children with ASD have no deficit in the second type of understanding, while they have difficulties in understanding others' intentions when they have to rely exclusively on motor cues. PMID:19440332

Hand rehabilitation using MIDI keyboard playing in adolescents with brain damage: a preliminary study.

PubMed

Chong, Hyun Ju; Cho, Sung-Rae; Kim, Soo Ji

2014-01-01

As a sequential, programmed movement of fingers, keyboard playing is a promising technique for inducing execution and a high level of coordination during finger movements. Also, keyboard playing can be physically and emotionally rewarding for adolescents in rehabilitation settings and thereby motivate continued involvement in treatment. The purpose of this study is to evaluate the effects of keyboard playing using Musical Instrument Digital Interface (MIDI) on finger movement for adolescents with brain damage. Eight adolescents with brain damage, ages 9 to 18 years (M = 13 years, SD = 2.78), in physical rehabilitation settings participated in this study. Measurements included MIDI keyboard playing for pressing force of the fingers and hand function tests (Grip and Pinch Power Test, Box and Block Test of Manual Dexterity [BBT], and the Jebsen Taylor Hand Function Test). Results showed increased velocity of all fingers on the MIDI-based test, and statistical significance was found in the velocity of F2 (index finger), F3 (middle finger), and F5 (little finger) between pre- and post-training tests. Correlation analysis between the pressing force of the finger and hand function tests showed a strong positive correlation between the measure of grip power and the pressing force of F2 and F5 on the Grip and Pinch Strength Test. All fingers showed strong correlation between MIDI results and BBT. For the Jebsen Taylor Hand Function Test, only the moving light objects task at post-training yielded strong correlation with MIDI results of all fingers. The results support using keyboard playing for hand rehabilitation, especially in the pressing force of individual finger sequential movements. Further investigation is needed to define the feasibility of the MIDI program for valid hand rehabilitation for people with brain damage.

Novel fiber optic sensor for grip testing

NASA Astrophysics Data System (ADS)

Zhao, Li Ping; Fang, Zhong Ping; Paul, Jinu; Ngoi, Bryan K. A.; Ng, Jun Hong

2004-12-01

Grip strength is an easy measure of skeletal muscle function as well as a powerful predictor of disability, morbidity and mortality. In order to measure the grip strength, a novel fiber optic approach is proposed and demonstrated. Strain dependent wavelength response of fiber Bragg gratings (FBGs) has been utilized to obtain the strength of individual fingers. Five FBGs are written at different center wavelengths on a single photosensitive fiber. Each FBG is used to get the response from each individual finger. The fiber containing the gratings is attached to a suitable grip holder, which can effectively transfer the grip force to the FBGs. An additional reference FBG is also provided to make the device temperature insensitive. Experimental results show that the wavelength shifts of the order of 0.2-0.5 nm can be achieved for individual fingers. The device is calibrated in terms of load to convert the wavelength shift to the strength of the grip. The time dependent wavelength fluctuations was also studied and presented in this paper.

Evaluation of four steering wheels to determine driver hand placement in a static environment.

PubMed

Mossey, Mary E; Xi, Yubin; McConomy, Shayne K; Brooks, Johnell O; Rosopa, Patrick J; Venhovens, Paul J

2014-07-01

While much research exists on occupant packaging both proprietary and in the literature, more detailed research regarding user preferences for subjective ratings of steering wheel designs is sparse in published literature. This study aimed to explore the driver interactions with production steering wheels in four vehicles by using anthropometric data, driver hand placement, and driver grip design preferences for Generation-Y and Baby Boomers. In this study, participants selected their preferred grip diameter, responded to a series of questions about the steering wheel grip as they sat in four vehicles, and rank ordered their preferred grip design. Thirty-two male participants (16 Baby Boomers between ages 47 and 65 and 16 Generation-Y between ages 18 and 29) participated in the study. Drivers demonstrated different gripping behavior between vehicles and between groups. Recommendations for future work in steering wheel grip design and naturalistic driver hand positioning are discussed. Copyright © 2014. Published by Elsevier Ltd.

Grip Analysis of Road Surface and Tire Footprint Using FEM

NASA Astrophysics Data System (ADS)

Sabri, M.; Abda, S.

2018-02-01

Road grip involve a touch between road pavement and the tire tread pattern. The load bearing surface, which depends on pavement roughness and local pressures in the contact patch. This research conducted to develop a Finite element model for simulating the experimentally testing of asphalt in Jl. AH Nasution Medan, North Sumatera Indonesia base on the value of grip coefficient from various tire loads and the various speed of the vehicle during contact to the road. A tire model and road pavement are developed for the analyses the geometry of tire footprint. The results showed that the greater the mass of car will increase grip coefficient. The coefficient of grip on the road surface contact trough the tire footprint strongly influence the kinetic coefficient of friction at certain speeds. Experimentally show that Concrete road grip coefficient of more than 34% compared to the asphalt road at the same IRI parameters (6-8). Kinetic friction coefficient more than 0.33 was obtained in a asphalt path at a speed of 30-40 Km/hour.

Large-scale GWAS identifies multiple loci for hand grip strength providing biological insights into muscular fitness.

PubMed

Willems, Sara M; Wright, Daniel J; Day, Felix R; Trajanoska, Katerina; Joshi, Peter K; Morris, John A; Matteini, Amy M; Garton, Fleur C; Grarup, Niels; Oskolkov, Nikolay; Thalamuthu, Anbupalam; Mangino, Massimo; Liu, Jun; Demirkan, Ayse; Lek, Monkol; Xu, Liwen; Wang, Guan; Oldmeadow, Christopher; Gaulton, Kyle J; Lotta, Luca A; Miyamoto-Mikami, Eri; Rivas, Manuel A; White, Tom; Loh, Po-Ru; Aadahl, Mette; Amin, Najaf; Attia, John R; Austin, Krista; Benyamin, Beben; Brage, Søren; Cheng, Yu-Ching; Cięszczyk, Paweł; Derave, Wim; Eriksson, Karl-Fredrik; Eynon, Nir; Linneberg, Allan; Lucia, Alejandro; Massidda, Myosotis; Mitchell, Braxton D; Miyachi, Motohiko; Murakami, Haruka; Padmanabhan, Sandosh; Pandey, Ashutosh; Papadimitriou, Ioannis; Rajpal, Deepak K; Sale, Craig; Schnurr, Theresia M; Sessa, Francesco; Shrine, Nick; Tobin, Martin D; Varley, Ian; Wain, Louise V; Wray, Naomi R; Lindgren, Cecilia M; MacArthur, Daniel G; Waterworth, Dawn M; McCarthy, Mark I; Pedersen, Oluf; Khaw, Kay-Tee; Kiel, Douglas P; Pitsiladis, Yannis; Fuku, Noriyuki; Franks, Paul W; North, Kathryn N; van Duijn, Cornelia M; Mather, Karen A; Hansen, Torben; Hansson, Ola; Spector, Tim; Murabito, Joanne M; Richards, J Brent; Rivadeneira, Fernando; Langenberg, Claudia; Perry, John R B; Wareham, Nick J; Scott, Robert A

2017-07-12

Hand grip strength is a widely used proxy of muscular fitness, a marker of frailty, and predictor of a range of morbidities and all-cause mortality. To investigate the genetic determinants of variation in grip strength, we perform a large-scale genetic discovery analysis in a combined sample of 195,180 individuals and identify 16 loci associated with grip strength (P<5 × 10 -8 ) in combined analyses. A number of these loci contain genes implicated in structure and function of skeletal muscle fibres (ACTG1), neuronal maintenance and signal transduction (PEX14, TGFA, SYT1), or monogenic syndromes with involvement of psychomotor impairment (PEX14, LRPPRC and KANSL1). Mendelian randomization analyses are consistent with a causal effect of higher genetically predicted grip strength on lower fracture risk. In conclusion, our findings provide new biological insight into the mechanistic underpinnings of grip strength and the causal role of muscular strength in age-related morbidities and mortality.

Decoding gripping force based on local field potentials recorded from subthalamic nucleus in humans

PubMed Central

Tan, Huiling; Pogosyan, Alek; Ashkan, Keyoumars; Green, Alexander L; Aziz, Tipu; Foltynie, Thomas; Limousin, Patricia; Zrinzo, Ludvic; Hariz, Marwan; Brown, Peter

2016-01-01

The basal ganglia are known to be involved in the planning, execution and control of gripping force and movement vigour. Here we aim to define the nature of the basal ganglia control signal for force and to decode gripping force based on local field potential (LFP) activities recorded from the subthalamic nucleus (STN) in patients with deep brain stimulation (DBS) electrodes. We found that STN LFP activities in the gamma (55–90 Hz) and beta (13–30m Hz) bands were most informative about gripping force, and that a first order dynamic linear model with these STN LFP features as inputs can be used to decode the temporal profile of gripping force. Our results enhance the understanding of how the basal ganglia control gripping force, and also suggest that deep brain LFPs could potentially be used to decode movement parameters related to force and movement vigour for the development of advanced human-machine interfaces. DOI: http://dx.doi.org/10.7554/eLife.19089.001 PMID:27855780

The Influence of Robotic Assistance on Reducing Neuromuscular Effort and Fatigue during Extravehicular Activity Glove Use

NASA Technical Reports Server (NTRS)

Madden, Kaci E.; Deshpande, Ashish D.; Peters, Benjamin J.; Rogers, Jonathan M.; Laske, Evan A.; McBryan, Emily R.

2017-01-01

The three-layered, pressurized space suit glove worn by Extravehicular Activity (EVA) crew members during missions commonly causes hand and forearm fatigue. The Spacesuit RoboGlove (SSRG), a Phase VI EVA space suit glove modified with robotic grasp-assist capabilities, has been developed to augment grip strength in order to improve endurance and reduce the risk of injury in astronauts. The overall goals of this study were to i) quantify the neuromuscular modulations that occur in response to wearing a conventional Phase VI space suit glove (SSG) during a fatiguing task, and ii) determine the efficacy of Spacesuit RoboGlove (SSRG) in reversing the adverse neuromuscular modulations and restoring altered muscular activity to barehanded levels. Six subjects performed a fatigue sequence consisting of repetitive dynamic-gripping interspersed with isometric grip-holds under three conditions: barehanded, wearing pressurized SSG, and wearing pressurized SSRG. Surface electromyography (sEMG) from six forearm muscles (flexor digitorum superficialis (FDS), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), extensor digitorum (ED), extensor carpi radialis longus (ECRL), and extensor carpi ulnaris (ECU)) and subjective fatigue ratings were collected during each condition. Trends in amplitude and spectral distributions of the sEMG signals were used to derive metrics quantifying neuromuscular effort and fatigue that were compared across the glove conditions. Results showed that by augmenting finger flexion, the SSRG successfully reduced the neuromuscular effort needed to close the fingers of the space suit glove in more than half of subjects during two types of tasks. However, the SSRG required more neuromuscular effort to extend the fingers compared to a conventional SSG in many subjects. Psychologically, the SSRG aided subjects in feeling less fatigued during short periods of intense work compared to the SSG. The results of this study reveal the promise of the SSRG as a grasp-assist device that can improve astronaut performance and reduce the risk of injury by offsetting neuromuscular effort. Modifications to the experimental protocol are needed, however, to improve the outcome of the neuromuscular fatigue metrics and determine the effectiveness of SSRG in increasing astronaut endurance. Nevertheless, these findings will improve the understanding of astronaut-spacesuit interaction and provide direction toward designing improved spacesuit gloves and robotic-assist devices, like the SSRG.

A development of assistant surgical robot system based on surgical-operation-by-wire and hands-on-throttle-and-stick.

PubMed

Kim, Myungjoon; Lee, Chiwon; Park, Woo Jung; Suh, Yun Suhk; Yang, Han Kwang; Kim, H Jin; Kim, Sungwan

2016-05-20

Robot-assisted laparoscopic surgery offers several advantages compared with open surgery and conventional minimally invasive surgery. However, one issue that needs to be resolved is a collision between the robot arm and the assistant instrument. This is mostly caused by miscommunication between the surgeon and the assistant. To resolve this limitation, an assistant surgical robot system that can be simultaneously manipulated via a wireless controller is proposed to allow the surgeon to control the assistant instrument. The system comprises two novel master interfaces (NMIs), a surgical instrument with a gripper actuated by a micromotor, and 6-axis robot arm. Two NMIs are attached to master tool manipulators of da Vinci research kit (dVRK) to control the proposed system simultaneously with patient side manipulators of dVRK. The developments of the surgical instrument and NMI are based on surgical-operation-by-wire concept and hands-on-throttle-and-stick concept from the earlier research, respectively. Tests for checking the accuracy, latency, and power consumption of the NMI are performed. The gripping force, reaction time, and durability are assessed to validate the surgical instrument. The workspace is calculated for estimating the clinical applicability. A simple peg task using the fundamentals of laparoscopic surgery board and an in vitro test are executed with three novice volunteers. The NMI was operated for 185 min and reflected the surgeon's decision successfully with a mean latency of 132 ms. The gripping force of the surgical instrument was comparable to that of conventional systems and was consistent even after 1000 times of gripping motion. The reaction time was 0.4 s. The workspace was calculated to be 8397.4 cm(3). Recruited volunteers were able to execute the simple peg task within the cut-off time and successfully performed the in vitro test without any collision. Various experiments were conducted and it is verified that the proposed assistant surgical robot system enables collision-free and simultaneous operation of the dVRK's robot arm and the proposed assistant robot arm. The workspace is appropriate for the performance of various kinds of surgeries. Therefore, the proposed system is expected to provide higher safety and effectiveness for the current surgical robot system.

Multimodal Encoding of Goal-Directed Actions in Monkey Ventral Premotor Grasping Neurons.

PubMed

Bruni, Stefania; Giorgetti, Valentina; Fogassi, Leonardo; Bonini, Luca

2017-01-01

Visuo-motor neurons of the ventral premotor area F5 encode "pragmatic" representations of object in terms of the potential motor acts (e.g., precision grip) afforded by it. Likewise, objects with identical pragmatic features (e.g., small spheres) but different behavioral value (e.g., edible or inedible) convey different "semantic" information and thus afford different goal-directed behaviors (e.g., grasp-to-eat or grasp-to-place). However, whether F5 neurons can extract distinct behavioral affordances from objects with similar pragmatic features is unknown. We recorded 134 F5 visuo-motor neurons in 2 macaques during a contextually cued go/no-go task in which the monkey grasped, or refrained from grasping, a previously presented edible or inedible target to eat it or placing it, respectively. Sixty-nine visuo-motor neurons showed motor selectivity for the target (35 food and 34 object), and about half of them (N = 35) exhibited congruent visual preference. Interestingly, when the monkey grasped in complete darkness and could identify the target only based on haptic feedback, visuo-motor neurons lost their precontact selectivity, but most of them (80%) showed it again 60 ms after hand-target contact. These findings suggest that F5 neurons possess a multimodal access to semantic information on objects, which are transformed into motor representations of the potential goal-directed actions afforded by them. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

GRIPs (Group Investigation Problems) for Introductory Physics

NASA Astrophysics Data System (ADS)

Moore, Thomas A.

2006-12-01

GRIPs lie somewhere between homework problems and simple labs: they are open-ended questions that require a mixture of problem-solving skills and hands-on experimentation to solve practical puzzles involving simple physical objects. In this talk, I will describe three GRIPs that I developed for a first-semester introductory calculus-based physics course based on the "Six Ideas That Shaped Physics" text. I will discuss the design of the three GRIPs we used this past fall, our experience in working with students on these problems, and students' response as reported on course evaluations.

Relationship Between Muscle Strength Asymmetry and Body Sway in Older Adults.

PubMed

Koda, Hitoshi; Kai, Yoshihiro; Murata, Shin; Osugi, Hironori; Anami, Kunihiko; Fukumoto, Takahiko; Imagita, Hidetaka

2018-05-31

The purpose of this study was to investigate the relationship between muscle strength asymmetry and body sway while walking. We studied 63 older adult women. Strong side and weak side of knee extension strength, toe grip strength, hand grip strength, and body sway while walking were measured. The relationship between muscle strength asymmetry for each muscle and body sway while walking was evaluated using Pearson's correlation coefficient. Regarding the muscles recognized to have significant correlation with body sway, the asymmetry cutoff value causing an increased sway was calculated. Toe grip strength asymmetry was significantly correlated with body sway. Toe grip strength asymmetry causing an increased body sway had a cutoff value of 23.5%. Our findings suggest toe grip strength asymmetry may be a target for improving gait stability.

The effects of grip width on sticking region in bench press.

PubMed

Gomo, Olav; Van Den Tillaar, Roland

2016-01-01

The aim of this study was to examine the occurrence of the sticking region by examining how three different grip widths affect the sticking region in powerlifters' bench press performance. It was hypothesised that the sticking region would occur at the same joint angle of the elbow and shoulder independent of grip width, indicating a poor mechanical region for vertical force production at these joint angles. Twelve male experienced powerlifters (age 27.7 ± 8.8 years, mass 91.9 ± 15.4 kg) were tested in one repetition maximum (1-RM) bench press with a narrow, medium and wide grip. Joint kinematics, timing, bar position and velocity were measured with a 3D motion capture system. All participants showed a clear sticking region with all three grip widths, but this sticking region was not found to occur at the same joint angles in all three grip widths, thereby rejecting the hypothesis that the sticking region would occur at the same joint angle of the elbow and shoulder independent of grip width. It is suggested that, due to the differences in moment arm of the barbell about the elbow joint in the sticking region, there still might be a poor mechanical region for total force production that is joint angle-specific.

Association between dietary protein intake and grip strength among adults aged 51 years and over: What We Eat in America, National Health and Nutrition Examination Survey 2011-2014.

PubMed

Mishra, Suruchi; Goldman, Joseph D; Sahyoun, Nadine R; Moshfegh, Alanna J

2018-01-01

Distributing daily protein intake evenly across meals (∼25-30g/meal) has been suggested to improve muscle mass. The aim of this research is to examine the association between grip strength, total protein intake and its distribution across day's meals in older adults. Nationally representative dietary intake data of adults aged 51 years and older (n = 4,123) who participated in What We Eat in America, NHANES 2011-2014 were analyzed. Protein intake per day and per eating occasion (breakfast, lunch, dinner, and snack) were determined. Combined grip strength was calculated and expressed in kilograms. Grip strength of individuals consuming ≥25g protein at 1 eating occasion was compared with those consuming same level of protein at 2 and 3 or more eating occasions. Grip strength of individuals in quartile 1 of daily protein intake was compared to those in the other quartiles. All associations were examined without and with adjustment for age, race/ethnicity, physical activity, health status, and smoking status. The comparison involving eating occasions and protein intake quartiles were further adjusted for daily protein intake and energy intake, respectively. Only 33% of men and 19% of women had protein intake of ≥25g at 2 or more eating occasions. These individuals also had higher grip strength and daily protein intake. Grip strength was positively associated with consumption of ≥25g protein at 2 eating occasions as compared to consumption of same level of protein at 1 eating occasion (p<0.05) in unadjusted model, but not when adjusted. Grip strength was positively associated with daily protein intake among women in quartiles 3 and 4 (p<0.05) of protein intake in both unadjusted and adjusted models compared to lowest protein intake. Among men, grip strength was associated with daily protein intake in quartiles 3 and 4 (p<0.05) in the unadjusted model, but not when adjusted. In a nationally representative sample of older adults, consuming ≥25g protein at 2 or more eating occasions was not associated with grip strength. However, higher daily protein intake was positively associated with grip strength in women.

Association between dietary protein intake and grip strength among adults aged 51 years and over: What We Eat in America, National Health and Nutrition Examination Survey 2011-2014

PubMed Central

Goldman, Joseph D.; Sahyoun, Nadine R.; Moshfegh, Alanna J.

2018-01-01

Introduction Distributing daily protein intake evenly across meals (∼25–30g/meal) has been suggested to improve muscle mass. The aim of this research is to examine the association between grip strength, total protein intake and its distribution across day’s meals in older adults. Methods Nationally representative dietary intake data of adults aged 51 years and older (n = 4,123) who participated in What We Eat in America, NHANES 2011–2014 were analyzed. Protein intake per day and per eating occasion (breakfast, lunch, dinner, and snack) were determined. Combined grip strength was calculated and expressed in kilograms. Grip strength of individuals consuming ≥25g protein at 1 eating occasion was compared with those consuming same level of protein at 2 and 3 or more eating occasions. Grip strength of individuals in quartile 1 of daily protein intake was compared to those in the other quartiles. All associations were examined without and with adjustment for age, race/ethnicity, physical activity, health status, and smoking status. The comparison involving eating occasions and protein intake quartiles were further adjusted for daily protein intake and energy intake, respectively. Results Only 33% of men and 19% of women had protein intake of ≥25g at 2 or more eating occasions. These individuals also had higher grip strength and daily protein intake. Grip strength was positively associated with consumption of ≥25g protein at 2 eating occasions as compared to consumption of same level of protein at 1 eating occasion (p<0.05) in unadjusted model, but not when adjusted. Grip strength was positively associated with daily protein intake among women in quartiles 3 and 4 (p<0.05) of protein intake in both unadjusted and adjusted models compared to lowest protein intake. Among men, grip strength was associated with daily protein intake in quartiles 3 and 4 (p<0.05) in the unadjusted model, but not when adjusted. Conclusion In a nationally representative sample of older adults, consuming ≥25g protein at 2 or more eating occasions was not associated with grip strength. However, higher daily protein intake was positively associated with grip strength in women. PMID:29364939

Hand grip strength and its correlation with vitamin D in Indian patients with hip fracture.

PubMed

Dhanwal, Dinesh K; Dharmshaktu, Pramila; Gautam, V K; Gupta, N; Saxena, Alpana

2013-01-01

This case-control study was performed to evaluate 25-hydroxyvitamin D [25(OH)D] deficiency and its correlation with hand grip strength in 95 Indian hip fracture subjects and 95 controls. 25(OH)D deficiency was found in 88.4 % of hip fracture subjects that was significantly higher as compared to controls. Hand grip strength as measured by hand held dynamometer was significantly lower in patients, and there was a significant positive correlation between 25(OH)D and hand grip strength. The present study was conducted to assess correlation between 25(OH) D and hand grip strength in hip fracture subjects residing in North India. Ninety-five patients with hip fracture and similar number of controls were enrolled in the study. Fasting venous samples were analyzed for 25(OH)D, intact parathyroid hormone (PTH), alkaline phosphatase, calcium, and phosphate. Hand grip strength of study subjects was measured using Jamar dynamometer. Correlation between vitamin D levels and hand grip strength was analyzed in study population. The mean age of hip fracture subjects was 61.4 ± 12.6 years which was comparable in men and women. Out of 95 subjects, 57 were men and 38 were women. Mean 25(OH)D levels were significantly lower whereas intact PTH levels were significantly higher in patient group compared controls (10.29 ± 6.53 vs 13.6 ± 4.01 ng/ml; 62.6 ± 59.3 vs 37.7 ± 28.8 pg/ml, respectively). The number of subjects with 25(OH)D deficiency and secondary hyperparathyroidism was significantly higher in hip fracture group. The mean hand grip strength among hip fracture subjects was significantly lower compared to that of controls (16.57 ± 5.74 vs 26.74 ± 5.23 kg). There was a significant positive correlation between 25(OH)D and hand grip strength ( r = 0.482, p value <0.01) in hip fracture population. Majority of hip fracture patients in India have vitamin D deficiency, secondary hyperparathyroidism, and lower hand grip strength compared to controls. Further, there is significant positive correlation between 25(OH)D and hand grip strength.

Manual therapy as an effective treatment for fibrosis in a rat model of upper extremity overuse injury

PubMed Central

Bove, Geoffrey M.; Harris, Michele Y; Zhao, Huaqing; Barbe, Mary F.

2016-01-01

Key clinical features of carpal tunnel syndrome and other types of cumulative trauma disorders of the hand and wrist include pain and functional disabilities. Mechanistic details remain under investigation but may involve tissue inflammation and/or fibrosis. We examined the effectiveness of modeled manual therapy (MMT) as a treatment for sensorimotor behavior declines and increased fibrogenic processes occurring in forearm tissues of rats performing an high repetition high force (HRHF) reaching and grasping task for 12 weeks. Young adult, female rats were examined: food restricted control rats (FRC, n=12); rats that were trained for 6 weeks before performing the HRHF task for 12 weeks with no treatment (HRHF-CON, n=11); and HRHF task rats received modeled manual therapy (HRHF-MMT, n=5) for 5 days/week for the duration of the 12-week of task. Rats receiving the MMT expressed fewer discomfort-related behaviors, and performed progressively better in the HRHF task. Grip strength, while decreased after training, improved following MMT. Fibrotic nerve and connective tissue changes (increased collagen and TGF-β1 deposition) present in 12-week HRHF-CON rats were significantly decreased in 12-week HRHF-MMT rats. These observations support the investigation of manual therapy as a preventative for repetitive motion disorders. PMID:26810536

Ergonomic design and evaluation of new surgical scissors.

PubMed

Shimomura, Yoshihiro; Shirakawa, Hironori; Sekine, Masashi; Katsuura, Tetsuo; Igarashi, Tatsuo

2015-01-01

The purpose of this study is to design a new surgical scissors handle and determine its effectiveness with various usability indices. A new scissors handle was designed that retains the professional grip but has the shapes of the eye rings modified to fit the thumb and ring finger and finger rests for the index and little finger. The newly designed scissors and traditional scissors were compared by electromyography, subjective evaluation and task performance in experiments using cutting and peeling tasks. The newly designed scissors reduced muscle load in both hand during cutting by the closing action, and reduced the muscle load in the left hand during peeling by the opening action through active use of the right hand. In evaluation by surgeons, task performance improved in addition to the decrease in muscle load. The newly designed scissors used in this study demonstrated high usability. A new scissors handle was designed that has the eye rings modified to fit the thumb and ring finger. The newly designed scissors reduced muscle load and enabled active use of the right hand. In evaluation by surgeons, task performance improved in addition to the decrease in muscle load.

Relationship between lung function and grip strength in older hospitalized patients: a pilot study

PubMed Central

Holmes, Sarah J; Allen, Stephen C; Roberts, Helen C

2017-01-01

Objective Older people with reduced respiratory muscle strength may be misclassified as having COPD on the basis of spirometric results. We aimed to evaluate the relationship between lung function and grip strength in older hospitalized patients without known airways disease. Methods Patients in acute medical wards were recruited who were aged ≥70 years; no history, symptoms, or signs of respiratory disease; Mini Mental State Examination ≥24; willing and able to consent to participate; and able to perform hand grip and forced spirometry. Data including lung function (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], FEV1/FVC, peak expiratory flow rate [PEFR], and slow vital capacity [SVC]), grip strength, age, weight, and height were recorded. Data were analyzed using descriptive statistics and linear regression unadjusted and adjusted (for age, height, and weight). Results A total of 50 patients (20 men) were recruited. Stronger grip strength in men was significantly associated with greater FEV1, but this was attenuated by adjustment for age, height, and weight. Significant positive associations were found in women between grip strength and both PEFR and SVC, both of which remained robust to adjustment. Conclusion The association between grip strength and PEFR and SVC may reflect stronger patients generating higher intrathoracic pressure at the start of spirometry and pushing harder against thoracic cage recoil at end-expiration. Conversely, patients with weaker grip strength had lower PEFR and SVC. These patients may be misclassified as having COPD on the basis of spirometric results. PMID:28458532

Normative Measurements of Grip and Pinch Strengths of 21st Century Korean Population

PubMed Central

Shim, Jin Hee; Kim, Jin Soo; Lee, Dong Chul; Ki, Sae Hwi; Yang, Jae Won; Jeon, Man Kyung; Lee, Sang Myung

2013-01-01

Background Measuring grip and pinch strength is an important part of hand injury evaluation. Currently, there are no standardized values of normal grip and pinch strength among the Korean population, and lack of such data prevents objective evaluation of post-surgical recovery in strength. This study was designed to establish the normal values of grip and pinch strength among the healthy Korean population and to identify any dependent variables affecting grip and pinch strength. Methods A cross-sectional study was carried out. The inclusion criterion was being a healthy Korean person without a previous history of hand trauma. The grip strength was measured using a Jamar dynamometer. Pulp and key pinch strength were measured with a hydraulic pinch gauge. Intra-individual and inter-individual variations in these variables were analyzed in a standardized statistical manner. Results There were a total of 336 healthy participants between 13 and 77 years of age. As would be expected in any given population, the mean grip and pinch strength was greater in the right hand than the left. Male participants (137) showed mean strengths greater than female participants (199) when adjusted for age. Among the male participants, anthropometric variables correlated positively with grip strength, but no such correlations were identifiable in female participants in a statistically significant way. Conclusions Objective measurements of hand strength are an important component of hand injury evaluation, and population-specific normative data are essential for clinical and research purposes. This study reports updated normative hand strengths of the South Korean population in the 21st century. PMID:23362480

Assessment of the presence/absence of the palmaris longus muscle in different sports, and elite and non-elite sport populations.

PubMed

Fowlie, Craig; Fuller, Colin; Pratten, Margaret K

2012-06-01

To investigate whether higher presence of the palmaris longus muscle is associated with sports that require hand grip. Cross-sectional study. Six hundred and forty-two medical students, members of sports clubs and national athletes. Participants were invited to complete a questionnaire that assessed their main sport, elite or non-elite level of participation, and level of activity. The presence of the palmaris longus was assessed visually using a standardised test. Presence of the palmaris longus, type of hand grip required for the sport and the level of participation. The presence of the palmaris longus was higher in elite athletes (21/22, 96%) than non-elite athletes (66/84, 79%; P=0.066) for sports that require a dominant-handed or two-handed cylindrical grip (18/22, 82% and 19/35, 54%, respectively; P=0.034). For both elite and non-elite athletes, the presence of the palmaris longus was higher in those participating in sustained grip sports (325/387, 84%) compared with sports that do not require a sustained grip (150/197, 76%; P=0.012). The palmaris longus may provide an advantage in certain types of sport that require hand grip, and for elite athletes participating in sports that require a dominant-handed or two-handed cylindrical hand grip. Orthopaedic specialists considering the use of the palmaris longus for a grafting procedure on an athlete should consider the level of participation and the type of hand grip required in the athlete's sport. Copyright © 2011 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Diet and its relationship with grip strength in community-dwelling older men and women: the Hertfordshire Cohort Study

PubMed Central

Robinson, Sian M; Jameson, Karen A; Batelaan, Sue F; Martin, Helen J; Syddall, Holly E; Dennison, Elaine M; Cooper, Cyrus; Sayer, Avan Aihie

2007-01-01

OBJECTIVES To examine relationships between diet and grip strength in older men and women, and to determine whether these relationships are modified by prenatal growth. DESIGN Cross-sectional and retrospective cohort study SETTING Hertfordshire, UK PARTICIPANTS Two thousand, nine hundred and eighty three men and women aged 59 to 73 years who were born and still live in Hertfordshire, UK MEASUREMENTS Weight at birth recorded in Health Visitor ledgers. Current food and nutrient intake assessed using an administered food frequency questionnaire, grip strength was measured with a hand-held dynamometer. RESULTS Grip strength was positively associated with height and weight at birth, and inversely related to age (all P<0.001). Of the dietary factors considered in relation to grip strength, the most important was fatty fish consumption. An increase in grip strength of 0.43kg (95% CI 0.13 to 0.74) in men (P=0.005), and 0.48kg (95% CI 0.24 to 0.72) in women (P<0.001), was observed for each additional portion of fatty fish consumed per week. These relationships were independent of adult height, age and birth weight, each of which had additive effects on grip strength. There was no evidence of interactive effects of weight at birth and adult diet on grip strength. CONCLUSION These data suggest that fatty fish consumption can have an important influence on muscle function in older men and women. This raises the possibility that the anti-inflammatory actions of n-3 fatty acids may play a role in the prevention of sarcopenia. PMID:18005355

The nature and distribution of affiliative behaviour during exposure to mild threat

PubMed Central

Grèzes, Julie; Dahl, Christoph D.

2017-01-01

Individual reactions to danger in humans are often characterized as antisocial and self-preservative. Yet, more than 50 years of research have shown that humans often seek social partners and behave prosocially when confronted by danger. This research has relied on post hoc verbal reports, which fall short of capturing the more spontaneous reactions to danger and determine their social nature. Real-world responses to danger are difficult to observe, due to their evanescent nature. Here, we took advantage of a series of photographs freely accessible online and provided by a haunted house attraction, which enabled us to examine the more immediate reactions to mild threat. Regarding the nature and structure of affiliative behaviour and their motivational correlates, we were able to analyse the distribution of gripping, a behaviour that could either be linked to self- or other-oriented protection. We found that gripping, an affiliative behaviour, was common, suggestive of the social nature of human immediate reactions to danger. We also found that, while gripping behaviour is quite stable across group sizes, mutual gripping dropped dramatically as group size increases. The fact that mutual gripping disappears when the number of available partners increases suggests that gripping behaviour most probably reflects a self-preservative motivation. We also found age class differences, with younger individuals showing more gripping but receiving little reciprocation. Also, the most exposed individuals received little mutual gripping. Altogether, these results suggest that primary reactions to threat in humans are driven by affiliative tendencies serving self-preservative motives. PMID:28878976

Laterality, spatial abilities, and accident proneness.

PubMed

Voyer, Susan D; Voyer, Daniel

2015-01-01

Although handedness as a measure of cerebral specialization has been linked to accident proneness, more direct measures of laterality are rarely considered. The present study aimed to fill that gap in the existing research. In addition, individual difference factors in accident proneness were further examined with the inclusion of mental rotation and navigation abilities measures. One hundred and forty participants were asked to complete the Mental Rotations Test, the Santa Barbara Sense of Direction scale, the Greyscales task, the Fused Dichotic Word Test, the Waterloo Handedness Questionnaire, and a grip strength task before answering questions related to number of accidents in five areas. Results indicated that handedness scores, absolute visual laterality score, absolute response time on the auditory laterality index, and navigation ability were significant predictors of the total number of accidents. Results are discussed with respect to cerebral hemispheric specialization and risk-taking attitudes and behavior.

Asymmetric training using virtual reality reflection equipment and the enhancement of upper limb function in stroke patients: a randomized controlled trial.

PubMed

Lee, DongJin; Lee, MyungMo; Lee, KyoungJin; Song, ChangHo

2014-07-01

Asymmetric movements with both hands contributed to the improvement of spatially coupled motion. Thus, the aim of this study was to investigate the effects of an asymmetric training program using virtual reality reflection equipment on upper limb function in stroke patients. Twenty-four stroke patients were randomly allocated to an experimental group (n=12) or a control group (n=12). Both groups participated in conventional physical therapy for 2×30 min/d, 5 d/wk, for 4 weeks. The experimental group also participated in an asymmetric training program using virtual reality reflection equipment, and the control group participated in a symmetric training program. Both asymmetric and symmetric programs were conducted for 30 min/d, 5 d/wk, for 4 weeks. To compare upper limb function before and after intervention, the Fugl-Meyer Assessment (FMA), the Box and Block Test (BBT), grip strength, range of motion (ROM), and spasticity were assessed. Both groups showed significant increases in upper limb function, excepting spasticity, after intervention (P<.05, 1-way repeated-measures analysis of variance [ANOVA]). A significant group-time interaction was demonstrated only for shoulder/elbow/wrist items of FMA, BBT, grip strength, and ROM of wrist flexion, extension, and ulnar deviation (P<.05, 2-way repeated-measures ANOVA). This study confirms that the asymmetric training program using virtual reality reflection equipment is an effective intervention method for improving upper limb function in stroke patients. We consider that an additional study based on a program using virtual reflection, which is more functional than performing simple tasks, and consisting of tasks relevant to the activities of daily living be conducted. Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Differential involvement of cortical and cerebellar areas using dominant and nondominant hands: An FMRI study

PubMed Central

Pardini, Matteo; Samson, Rebecca S.; D'Angelo, Egidio; Friston, Karl J.; Toosy, Ahmed T.; Gandini Wheeler‐Kingshott, Claudia A.M.

2015-01-01

Abstract Motor fMRI studies, comparing dominant (DH) and nondominant (NDH) hand activations have reported mixed findings, especially for the extent of ipsilateral (IL) activations and their relationship with task complexity. To date, no study has directly compared DH and NDH activations using an event‐related visually guided dynamic power‐grip paradigm with parametric (three) forces (GF) in healthy right‐handed subjects. We implemented a hierarchical statistical approach aimed to: (i) identify the main effect networks engaged when using either hand; (ii) characterise DH/NDH responses at different GFs; (iii) assess contralateral (CL)/IL‐specific and hemisphere‐specific activations. Beyond confirming previously reported results, this study demonstrated that increasing GF has an effect on motor response that is contextualised also by the use of DH or NDH. Linear analysis revealed increased activations in sensorimotor areas, with additional increased recruitments of subcortical and cerebellar areas when using the NDH. When looking at CL/IL‐specific activations, CL sensorimotor areas and IL cerebellum were activated with both hands. When performing the task with the NDH, several areas were also recruited including the CL cerebellum. Finally, there were hand‐side‐independent activations of nonmotor‐specific areas in the right and left hemispheres, with the right hemisphere being involved more extensively in sensori‐motor integration through associative areas while the left hemisphere showing greater activation at higher GF. This study shows that the functional networks subtending DH/NDH power‐grip visuomotor functions are qualitatively and quantitatively distinct and this should be taken into consideration when performing fMRI studies, particularly when planning interventions in patients with specific impairments. Hum Brain Mapp 36:5079–5100, 2015. © 2015 Wiley Periodicals, Inc. PMID:26415818

Kinematic performance of a six degree-of-freedom hand model (6DHand) for use in occupational biomechanics.

PubMed

Buczek, Frank L; Sinsel, Erik W; Gloekler, Daniel S; Wimer, Bryan M; Warren, Christopher M; Wu, John Z

2011-06-03

Upper extremity musculoskeletal disorders represent an important health issue across all industry sectors; as such, the need exists to develop models of the hand that provide comprehensive biomechanics during occupational tasks. Previous optical motion capture studies used a single marker on the dorsal aspect of finger joints, allowing calculation of one and two degree-of-freedom (DOF) joint angles; additional algorithms were needed to define joint centers and the palmar surface of fingers. We developed a 6DOF model (6DHand) to obtain unconstrained kinematics of finger segments, modeled as frusta of right circular cones that approximate the palmar surface. To evaluate kinematic performance, twenty subjects gripped a cylindrical handle as a surrogate for a powered hand tool. We hypothesized that accessory motions (metacarpophalangeal pronation/supination; proximal and distal interphalangeal radial/ulnar deviation and pronation/supination; all joint translations) would be small (less than 5° rotations, less than 2mm translations) if segment anatomical reference frames were aligned correctly, and skin movement artifacts were negligible. For the gripping task, 93 of 112 accessory motions were small by our definition, suggesting this 6DOF approach appropriately models joints of the fingers. Metacarpophalangeal supination was larger than expected (approximately 10°), and may be adjusted through local reference frame optimization procedures previously developed for knee kinematics in gait analysis. Proximal translations at the metacarpophalangeal joints (approximately 10mm) were explained by skin movement across the metacarpals, but would not corrupt inverse dynamics calculated for the phalanges. We assessed performance in this study; a more rigorous validation would likely require medical imaging. Published by Elsevier Ltd.

A randomised controlled trial of sensory awareness training and additional motor practice for learning scalpel skills in podiatry students.

PubMed

Causby, Ryan S; McDonnell, Michelle N; Reed, Lloyd; Hillier, Susan L

2016-12-05

The process of using a scalpel, like all other motor activities, is dependent upon the successful integration of afferent (sensory), cognitive and efferent (motor) processes. During learning of these skills, even if motor practice is carefully monitored there is still an inherent risk involved. It is also possible that this strategy could reinforce high levels of anxiety experienced by the student and affect student self-efficacy, causing detrimental effects on motor learning. An alternative training strategy could be through targeting sensory rather than motor processes. Second year podiatry students who were about to commence learning scalpel skills were recruited. Participants were randomly allocated into sensory awareness training (Sensory), additional motor practice (Motor) or usual teaching only (Control) groups. Participants were then evaluated on psychological measures (Intrinsic Motivation Inventory) and dexterity measures (Purdue Pegboard, Grooved Pegboard Test and a grip-lift task). A total of 44 participants were included in the study. There were no baseline differences or significant differences between the three groups over time on the Perceived Competence, Effort/ Importance or Pressure/ Tension, psychological measures. All groups showed a significant increase in Perceived Competence over time (F 1,41  = 13.796, p = 0.001). Only one variable for the grip-lift task (Preload Duration for the non-dominant hand) showed a significant difference over time between the groups (F 2,41  = 3.280, p = 0.038), specifically, Motor and Control groups. The use of sensory awareness training, or additional motor practice did not provide a more effective alternative compared with usual teaching. Further research may be warranted using more engaged training, provision of supervision and greater participant numbers. Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12616001428459 . Registered 13 th October 2016. Registered Retrospectively.

77 FR 23638 - Airworthiness Directives; Bell Helicopter Textron, Incorporated Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-20

... cycles for each grip on a component history card or equivalent record. Additionally, that AD requires you... each grip on a component history card or equivalent record. On the single-engine model helicopters, one... grip on a component history card or equivalent record. For each month that the hours TIS cannot be...

ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

DOEpatents

Young, J.N.

1957-08-20

An electromagnetic device for moving an object in a linear path by increments is described. The device is specifically adapted for moving a neutron absorbing control rod into and out of the core of a reactor and consists essentially of an extension member made of magnetic material connected to one end of the control rod and mechanically flexible to grip the walls of a sleeve member when flexed, a magnetic sleeve member coaxial with and slidable between limit stops along the flexible extension, electromagnetic coils substantially centrally located with respect to the flexible extension to flex the extension member into gripping engagement with the sleeve member when ener gized, moving electromagnets at each end of the sleeve to attract the sleeve when energized, and a second gripping electromagnet positioned along the flexible extension at a distance from the previously mentioned electromagnets for gripping the extension member when energized. In use, the second gripping electromagnet is deenergized, the first gripping electromagnet is energized to fix the extension member in the sleeve, and one of the moving electromagnets is energized to attract the sleeve member toward it, thereby moving the control rod.

Switching in Feedforward Control of Grip Force During Tool-Mediated Interaction With Elastic Force Fields

PubMed Central

White, Olivier; Karniel, Amir; Papaxanthis, Charalambos; Barbiero, Marie; Nisky, Ilana

2018-01-01

Switched systems are common in artificial control systems. Here, we suggest that the brain adopts a switched feedforward control of grip forces during manipulation of objects. We measured how participants modulated grip force when interacting with soft and rigid virtual objects when stiffness varied continuously between trials. We identified a sudden phase transition between two forms of feedforward control that differed in the timing of the synchronization between the anticipated load force and the applied grip force. The switch occurred several trials after a threshold stiffness level in the range 100–200 N/m. These results suggest that in the control of grip force, the brain acts as a switching control system. This opens new research questions as to the nature of the discrete state variables that drive the switching. PMID:29930504

Grip strength is not associated with incident type 2 diabetes mellitus in healthy adults: The CoLaus study.

PubMed

Marques-Vidal, Pedro; Vollenweider, Peter; Waeber, Gérard; Jornayvaz, François R

2017-10-01

We examined the association of grip strength with incident type 2 diabetes mellitus (T2DM) in healthy subjects initially aged 50 to 75years after a follow-up of 5.5years and 10.7years. This was a prospective, population-based study derived from the CoLaus (Cohorte Lausannoise) study including 2318 participants (aged 60.2y; 1354 women) free from T2DM at baseline. Grip strength was assessed using a handheld dynamometer. The effect of grip strength on the incidence of T2DM was analyzed by logistic regression. After a follow-up of 5.5years, 190 (8.2%) T2DM cases were identified. In bivariate analysis, participants who developed T2DM had a higher absolute grip strength (35.3±10.6 versus 33.2±10.7kg, P=0.013). Analysis between grip strength expressed in 5kg increment and incident TD2M showed a negative association when adjusted for age and sex [ORs (95% CI): 0.88 (0.79, 0.98)], or for age, sex and body mass index (BMI) [ORs (95% CI): 0.87 (0.78, 097)]. After a follow-up of 10.7years, 131 supplemental (7.3%) T2DM cases were identified, but there was no association between grip strength and incident T2DM in bivariate and multivariable analysis, potentially due to a lack of statistical power. In non elderly healthy adults, the risk of incident T2DM is overall not associated with grip strength over a maximum follow-up of 10.7years. Future studies are warranted to better assess the association between grip strength and incident T2DM in bigger and even younger cohorts. Copyright © 2017 Elsevier B.V. All rights reserved.

Association of the AMPA receptor-related postsynaptic density proteins GRIP and ABP with subsets of glutamate-sensitive neurons in the rat retina.

PubMed

Gábriel, Robert; de Souza, Sunita; Ziff, Edward B; Witkovsky, Paul

2002-07-22

We used specific antibodies against two postsynaptic density proteins, GRIP (glutamate receptor interacting protein) and ABP (AMPA receptor-binding protein), to study their distribution in the rat retina. In the central nervous system, it has been shown that both proteins bind strongly to the AMPA glutamate receptor (GluR) 2/3 subunits, but not other GluRs, through a set of three PDZ domains. Western blots detected a single GRIP protein that was virtually identical in retina and brain, whereas retinal ABP corresponded to only one of three ABP peptides found in brain. The retinal distributions of GluR2/3, GRIP, and ABP immunoreactivity (IR) were similar but not identical. GluR2/3 immunoreactivity (IR) was abundant in both plexiform layers and in large perikarya. ABP IR was concentrated in large perikarya but was sparse in the plexiform layers, whereas GRIP IR was relatively more abundant in the plexiform layers than in perikarya. Immunolabel for these three antibodies consisted of puncta < or = 0.2 microm in diameter. The cellular localization of GRIP and ABP IR was examined by double labeling subclasses of retinal neuron with characteristic marker proteins, e.g., calbindin. GRIP, ABP, and GluR2/3 IR were detected in horizontal cells, dopaminergic and glycinergic AII amacrine cells and large ganglion cells. Immunolabel was absent in rod bipolar and weak or absent in cholinergic amacrine cells. By using the tyramide method of signal amplification, a colocalization of GluR2/3 was found with either GRIP or ABP in horizontal cell terminals, and perikarya of amacrine and ganglion cells. Our results show that ABP and GRIP colocalize with GluR2/3 in particular subsets of retinal neuron, as was previously established for certain neurons in the brain. Copyright 2002 Wiley-Liss, Inc.

The Design of the Automatic Control System of the Gripping-Belt Speed in Long-Rootstalk Traditional Chinese Herbal Harvester

NASA Astrophysics Data System (ADS)

Huang, Jinxia; Wang, Junfa; Yu, Yonghong

This article aims to design a kind of gripping-belt speed automatic tracking system of traditional Chinese herbal harvester by AT89C52 single-chip micro computer as a core combined with fuzzy PID control algorithm. The system can adjust the gripping-belt speed in accordance with the variation of the machine's operation, so there is a perfect matching between the machine operation speed and the gripping-belt speed. The harvesting performance of the machine can be improved greatly. System design includes hardware and software.

GRIPS Plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1978-07-31

The GRIPS (Geothermal Resources Impact Projection Study) Commission was established by a Joint Powers Agreement between the California Counties of Lake, Mendocino, Napa, and Sonoma. The objectives of GRIPS are primarily to develop and use a cooperative environmental data collection and use system including natural, social, and economic considerations to facilitate their independent decisions and those of State and Federal agencies related to the environmental effects of geothermal development. This GRIPS Plan was prepared from a wide range of studies, workshops, and staff analyses. The plan is presented in four parts: summary and introduction; environmental data status report; planned programs;more » and budget. (MHR)« less

Task based exposure assessment in ergonomic epidemiology: a study of upper arm elevation in the jobs of machinists, car mechanics, and house painters

PubMed Central

Svendsen, S; Mathiassen, S; Bonde, J

2005-01-01

Aims: To explore the precision of task based estimates of upper arm elevation in three occupational groups, compared to direct measurements of job exposure. Methods: Male machinists (n = 26), car mechanics (n = 23), and house painters (n = 23) were studied. Whole day recordings of upper arm elevation were obtained for four consecutive working days, and associated task information was collected in diaries. For each individual, task based estimates of job exposure were calculated by weighting task exposures from a collective database by task proportions according to the diaries. These estimates were validated against directly measured job exposures using linear regression. The performance of the task based approach was expressed through the gain in precision of occupational group mean exposures that could be obtained by adding subjects with task based estimates to a group of subjects with measured job exposures in a "validation" design. Results: In all three occupations, tasks differed in mean exposure, and task proportions varied between individuals. Task based estimation proved inefficient, with squared correlation coefficients only occasionally exceeding 0.2 for the relation between task based and measured job exposures. Consequently, it was not possible to substantially improve the precision of an estimated group mean by including subjects whose job exposures were based on task information. Conclusions: Task based estimates of mechanical job exposure can be very imprecise, and only marginally better than estimates based on occupation. It is recommended that investigators in ergonomic epidemiology consider the prospects of task based exposure assessment carefully before placing resources at obtaining task information. Strategies disregarding tasks may be preferable in many cases. PMID:15613604

Can grip strength be used as a surrogate marker to monitor recovery from shoulder fatigue?

PubMed

Hawkes, David; Grant, Michael; McMahon, Jessica; Horsley, Ian; Khaiyat, Omid

2018-06-06

Muscular fatigue impacts on normal shoulder function, which is particularly pertinent to throwing athletes. This study aimed to investigate the relationship between grip strength and shoulder muscle fatigue to evaluate the role of grip strength as a surrogate measure for upper limb performance. Twenty healthy participants were recruited. EMG was recorded from 15 shoulder muscles during different fatiguing contractions: an initial baseline recording (Fat-Baseline); after a shoulder exhausting exercise regime (Fat-Exhaustion); and after a 10 min rest period (Fat-Recovery). Grip strength was similarly measured in the same conditions. Grip strength differed significantly across the testing scenarios (p = 0.012-<0.001). Greater fatigue was seen in anterior deltoid, middle deltoid, posterior deltoid and supraspinatus in the Fat-Exhaustion contraction as compared to the Fat-Baseline contraction (p = <0.001-0.043). Greater fatigue was seen during the Fat-Recovery contraction for the trapezius, serratus anterior and biceps brachii as compared to the Fat-Exhaustion contraction (p = 0.008-0.038). Grip strength decreased following an exhausting exercise protocol but recovered to baseline following a rest period. Conversely, EMG indices of fatigue did not recover. Additional fatigue was seen reflecting a reorganisation of movement strategy. Therefore, susceptibility to injury still exists if grip strength alone is used as a barometer of upper limb performance. Copyright © 2018. Published by Elsevier Ltd.

Ergonomic evaluation of a mechanical anastomotic stapler used by Japanese surgeons.

PubMed

Kono, Emiko; Tada, Mitsunori; Kouchi, Makiko; Endo, Yui; Tomizawa, Yasuko; Matsuo, Tomoko; Nomura, Sachiyo

2014-06-01

The satisfaction rating of currently available mechanical staplers for Japanese surgeons with small hands is low. To identify the issue, we examined the relationship of hand dimensions and grip force with the operation force of a mechanical circular stapler. Hand dimensions and grip force were measured in 113 Japanese surgeons (52 men and 61 women). We then evaluated the relationship between grip width and the operation force required to push the lever of the stapler, at three points on the lever, using a digital force gauge. The optimal grip width of the dominant hand was 62.5 ± 8.5 mm for men and 55.5 ± 5.9 mm for women (p < 0.001). The maximum grip force of the dominant hand was 44.2 ± 6.1 kg for men and 29.7 ± 4.5 kg for women (p < 0.001) and the maximum operation force required to push the lever 7.0, 45.0, and 73.0 mm from the end of the lever was 21.8, 28.6, and 42.4 kg, respectively. To our knowledge, this is the first ergonomic study of a surgical stapler to be conducted in Asia. Firing the stapler by gripping the proximal side of the lever is physically impossible for most Japanese women surgeons since the required operation force exceeds the maximum grip force, which probably accounts for the stress perceived by these women.

Output control of da Vinci surgical system's surgical graspers.

PubMed

Johnson, Paul J; Schmidt, David E; Duvvuri, Umamaheswar

2014-01-01

The number of robot-assisted surgeries performed with the da Vinci surgical system has increased significantly over the past decade. The articulating movements of the robotic surgical grasper are controlled by grip controls at the master console. The user interface has been implicated as one contributing factor in surgical grasping errors. The goal of our study was to characterize and evaluate the user interface of the da Vinci surgical system in controlling surgical graspers. An angular manipulator with force sensors was used to increment the grip control angle as grasper output angles were measured. Input force at the grip control was simultaneously measured throughout the range of motion. Pressure film was used to assess the maximum grasping force achievable with the endoscopic grasping tool. The da Vinci robot's grip control angular input has a nonproportional relationship with the grasper instrument output. The grip control mechanism presents an intrinsic resistant force to the surgeon's fingertips and provides no haptic feedback. The da Vinci Maryland graspers are capable of applying up to 5.1 MPa of local pressure. The angular and force input at the grip control of the da Vinci robot's surgical graspers is nonproportional to the grasper instrument's output. Understanding the true relationship of the grip control input to grasper instrument output may help surgeons understand how to better control the surgical graspers and promote fewer grasping errors. Copyright © 2014 Elsevier Inc. All rights reserved.

Analysis and Test Support for Phillips Laboratory Precision Structures

DTIC Science & Technology

1998-11-01

Air Force Research Laboratory ( AFRL ), Phillips Research Site . Task objectives centered...around analysis and structural dynamic test support on experiments within the Space Vehicles Directorate at Kirtland Air Force Base. These efforts help...support for Phillips Laboratory Precision Structures." Mr. James Goodding of CSA Engineering was the principal investigator for this task. Mr.

GRIP Experiment

NASA Image and Video Library

2018-06-11

iss056e009784 (June 11, 2018) --- Expedition 56 Flight Engineer Alexander Gerst of the European Space Agency (ESA) is seated in the Columbus laboratory module participating in the Grip study. Grip is an ESA-sponsored experiment that is researching how the nervous system adapts to microgravity. Observations may improve the design of safer space habitats and help patients on Earth with neurological diseases.

GRIP Experiment

NASA Image and Video Library

2018-06-11

iss056e009783 (June 11, 2018) --- Expedition 56 Flight Engineer Alexander Gerst of the European Space Agency (ESA) is seated in the Columbus laboratory module participating in the Grip study. Grip is an ESA-sponsored experiment that is researching how the nervous system adapts to microgravity. Observations may improve the design of safer space habitats and help patients on Earth with neurological diseases.

Grip Experiment 2010

NASA Image and Video Library

2010-08-16

A researcher with the Genesis and Rapid Intensification Processes (GRIP) experiment works aboard the NASA DC-8 during a flight over the Gulf of Mexico, Tuesday, Aug. 17, 2010. GRIP is a NASA Earth science field experiment in 2010 that is being conducted to better understand how tropical storms form and develop into major hurricanes. Photo Credit: (NASA/Paul E. Alers)

16 CFR Figure 5 to Part 1512 - Typical Handbrake Actuator Showing Grip Dimension

Code of Federal Regulations, 2010 CFR

2010-01-01

... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Typical Handbrake Actuator Showing Grip Dimension 5 Figure 5 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 5 Figure 5 to Part 1512—Typical Handbrake Actuator Showing Grip Dimension...

16 CFR Figure 5 to Part 1512 - Typical Handbrake Actuator Showing Grip Dimension

Code of Federal Regulations, 2011 CFR

2011-01-01

... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Typical Handbrake Actuator Showing Grip Dimension 5 Figure 5 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 5 Figure 5 to Part 1512—Typical Handbrake Actuator Showing Grip Dimension...

16 CFR Figure 5 to Part 1512 - Typical Handbrake Actuator Showing Grip Dimension

Code of Federal Regulations, 2013 CFR

2013-01-01

... 16 Commercial Practices 2 2013-01-01 2013-01-01 false Typical Handbrake Actuator Showing Grip Dimension 5 Figure 5 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 5 Figure 5 to Part 1512—Typical Handbrake Actuator Showing Grip Dimension...

16 CFR Figure 5 to Part 1512 - Typical Handbrake Actuator Showing Grip Dimension

Code of Federal Regulations, 2012 CFR

2012-01-01

... 16 Commercial Practices 2 2012-01-01 2012-01-01 false Typical Handbrake Actuator Showing Grip Dimension 5 Figure 5 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 5 Figure 5 to Part 1512—Typical Handbrake Actuator Showing Grip Dimension...

16 CFR Figure 5 to Part 1512 - Typical Handbrake Actuator Showing Grip Dimension

Code of Federal Regulations, 2014 CFR

2014-01-01

... 16 Commercial Practices 2 2014-01-01 2014-01-01 false Typical Handbrake Actuator Showing Grip Dimension 5 Figure 5 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 5 Figure 5 to Part 1512—Typical Handbrake Actuator Showing Grip Dimension...

Case-study of a user-driven prosthetic arm design: bionic hand versus customized body-powered technology in a highly demanding work environment.

PubMed

Schweitzer, Wolf; Thali, Michael J; Egger, David

2018-01-03

Prosthetic arm research predominantly focuses on "bionic" but not body-powered arms. However, any research orientation along user needs requires sufficiently precise workplace specifications and sufficiently hard testing. Forensic medicine is a demanding environment, also physically, also for non-disabled people, on several dimensions (e.g., distances, weights, size, temperature, time). As unilateral below elbow amputee user, the first author is in a unique position to provide direct comparison of a "bionic" myoelectric iLimb Revolution (Touch Bionics) and a customized body-powered arm which contains a number of new developments initiated or developed by the user: (1) quick lock steel wrist unit; (2) cable mount modification; (3) cast shape modeled shoulder anchor; (4) suspension with a soft double layer liner (Ohio Willowwood) and tube gauze (Molnlycke) combination. The iLimb is mounted on an epoxy socket; a lanyard fixed liner (Ohio Willowwood) contains magnetic electrodes (Liberating Technologies). An on the job usage of five years was supplemented with dedicated and focused intensive two-week use tests at work for both systems. The side-by-side comparison showed that the customized body-powered arm provides reliable, comfortable, effective, powerful as well as subtle service with minimal maintenance; most notably, grip reliability, grip force regulation, grip performance, center of balance, component wear down, sweat/temperature independence and skin state are good whereas the iLimb system exhibited a number of relevant serious constraints. Research and development of functional prostheses may want to focus on body-powered technology as it already performs on manually demanding and heavy jobs whereas eliminating myoelectric technology's constraints seems out of reach. Relevant testing could be developed to help expediting this. This is relevant as Swiss disability insurance specifically supports prostheses that enable actual work integration. Myoelectric and cosmetic arm improvement may benefit from a less forgiving focus on perfecting anthropomorphic appearance.

Grip Strength Is Associated With Cognitive Performance in Schizophrenia and the General Population: A UK Biobank Study of 476559 Participants.

PubMed

Firth, Joseph; Stubbs, Brendon; Vancampfort, Davy; Firth, Josh A; Large, Matthew; Rosenbaum, Simon; Hallgren, Mats; Ward, Philip B; Sarris, Jerome; Yung, Alison R

2018-06-06

Handgrip strength may provide an easily-administered marker of cognitive functional status. However, further population-scale research examining relationships between grip strength and cognitive performance across multiple domains is needed. Additionally, relationships between grip strength and cognitive functioning in people with schizophrenia, who frequently experience cognitive deficits, has yet to be explored. Baseline data from the UK Biobank (2007-2010) was analyzed; including 475397 individuals from the general population, and 1162 individuals with schizophrenia. Linear mixed models and generalized linear mixed models were used to assess the relationship between grip strength and 5 cognitive domains (visual memory, reaction time, reasoning, prospective memory, and number memory), controlling for age, gender, bodyweight, education, and geographical region. In the general population, maximal grip strength was positively and significantly related to visual memory (coefficient [coeff] = -0.1601, standard error [SE] = 0.003), reaction time (coeff = -0.0346, SE = 0.0004), reasoning (coeff = 0.2304, SE = 0.0079), number memory (coeff = 0.1616, SE = 0.0092), and prospective memory (coeff = 0.3486, SE = 0.0092: all P < .001). In the schizophrenia sample, grip strength was strongly related to visual memory (coeff = -0.155, SE = 0.042, P < .001) and reaction time (coeff = -0.049, SE = 0.009, P < .001), while prospective memory approached statistical significance (coeff = 0.233, SE = 0.132, P = .078), and no statistically significant association was found with number memory and reasoning (P > .1). Grip strength is significantly associated with cognitive functioning in the general population and individuals with schizophrenia, particularly for working memory and processing speed. Future research should establish directionality, examine if grip strength also predicts functional and physical health outcomes in schizophrenia, and determine whether interventions which improve muscular strength impact on cognitive and real-world functioning.

The Effects of Industrial Protective Gloves and Hand Skin Temperatures on Hand Grip Strength and Discomfort Rating

PubMed Central

2017-01-01

Daily working activities and functions require a high contribution of hand and forearm muscles in executing grip force. To study the effects of wearing different gloves on grip strength, under a variety of hand skin temperatures, an assessment of the maximum grip strength was performed with 32 healthy male workers with a mean age (standard deviation) of 30.44 (5.35) years wearing five industrial gloves at three hand skin temperatures. Their ages and anthropometric characteristics including body mass index (BMI), hand length, hand width, hand depth, hand palm, and wrist circumference were measured. The hand was exposed to different bath temperatures (5 °C, 25 °C, and 45 °C) and hand grip strength was measured using a Jamar hydraulic hand dynamometer with and without wearing the gloves (chemical protection glove, rubber insulating glove, anti-vibration impact glove, cotton yarn knitted glove, and RY-WG002 working glove). The data were analyzed using the Shapiro–Wilk test, Pearson correlation coefficient, Tukey test, and analysis of variance (ANOVA) of the within-subject design analysis. The results showed that wearing gloves significantly affected the maximum grip strength. Wearing the RY-WG002 working glove produced a greater reduction on the maximum grip when compared with the bare hand, while low temperatures (5 °C) had a significant influence on grip when compared to medium (25 °C) and high (45 °C) hand skin temperatures. In addition, participants felt more discomfort in both environmental extreme conditions. Furthermore, they reported more discomfort while wearing neoprene, rubber, and RY-WG002 working gloves. PMID:29207573

Longitudinal assessment of grip strength using bulb dynamometer in Duchenne Muscular Dystrophy

PubMed Central

Pizzato, Tatiana M.; Baptista, Cyntia R. J. A.; Souza, Mariana A.; Benedicto, Michelle M. B.; Martinez, Edson Z.; Mattiello-Sverzut, Ana C.

2014-01-01

BACKGROUND: Grip strength is used to infer functional status in several pathological conditions, and the hand dynamometer has been used to estimate performance in other areas. However, this relationship is controversial in neuromuscular diseases and studies with the bulb dynamometer comparing healthy children and children with Duchenne Muscular Dystrophy (DMD) are limited. OBJECTIVE: The evolution of grip strength and the magnitude of weakness were examined in boys with DMD compared to healthy boys. The functional data of the DMD boys were correlated with grip strength. METHOD: Grip strength was recorded in 18 ambulant boys with DMD (Duchenne Group, DG) aged 4 to 13 years (mean 7.4±2.1) and 150 healthy volunteers (Control Group, CG) age-matched using a bulb dynamometer (North Coast- NC70154). The follow-up of the DG was 6 to 33 months (3-12 sessions), and functional performance was verified using the Vignos scale. RESULTS: There was no difference between grip strength obtained by the dominant and non-dominant side for both groups. Grip strength increased in the CG with chronological age while the DG remained stable or decreased. The comparison between groups showed significant difference in grip strength, with CG values higher than DG values (confidence interval of 95%). In summary, there was an increment in the differences between the groups with increasing age. Participants with 24 months or more of follow-up showed a progression of weakness as well as maintained Vignos scores. CONCLUSIONS: The amplitude of weakness increased with age in the DG. The bulb dynamometer detected the progression of muscular weakness. Functional performance remained virtually unchanged in spite of the increase in weakness. PMID:25003277

Association between grip strength and diabetes prevalence in black, South-Asian, and white European ethnic groups: a cross-sectional analysis of 418 656 participants in the UK Biobank study.

PubMed

Ntuk, U E; Celis-Morales, C A; Mackay, D F; Sattar, N; Pell, J P; Gill, J M R

2017-08-01

To quantify the extent to which ethnic differences in muscular strength might account for the substantially higher prevalence of diabetes in black and South-Asian compared with white European adults. This cross-sectional study used baseline data from the UK Biobank study on 418 656 white European, black and South-Asian participants, aged 40-69 years, who had complete data on diabetes status and hand-grip strength. Associations between hand-grip strength and diabetes were assessed using logistic regression and were adjusted for potential confounding factors. Lower grip strength was associated with higher prevalence of diabetes, independent of confounding factors, across all ethnicities in both men and women. Diabetes prevalence was approximately three- to fourfold higher in South-Asian and two- to threefold higher in black participants compared with white European participants across all levels of grip strength, but grip strength in South-Asian men and women was ~ 5-6 kg lower than in the other ethnic groups. Thus, the attributable risk for diabetes associated with low grip strength was substantially higher in South-Asian participants (3.9 and 4.2 cases per 100 men and women, respectively) than in white participants (2.0 and 0.6 cases per 100 men and women, respectively). Attributable risk associated with low grip strength was also high in black men (4.3 cases) but not in black women (0.4 cases). Low strength is associated with a disproportionately large number of diabetes cases in South-Asian men and women and in black men. Trials are needed to determine whether interventions to improve strength in these groups could help reduce ethnic inequalities in diabetes prevalence. © 2017 Diabetes UK.

Grip Strength as a Marker of Hypertension and Diabetes in Healthy Weight Adults

PubMed Central

Mainous, Arch G.; Tanner, Rebecca J.; Anton, Stephen D.; Jo, Ara

2015-01-01

Introduction Muscle strength may play a role in cardiometabolic disease. We examined the relationship between hand grip strength and diabetes and hypertension in a sample of healthy weight adults. Methods In 2015, we analyzed the National Health and Nutrition Examination Survey 2011–2012 for adults aged ≥20 years with healthy BMIs (between 18.5 and <25 kg/m2) and no history of cardiovascular disease (unweighted n=1,469; weighted n=61,672,082). Hand grip strength was assessed with a dynamometer. Diabetes was based on hemoglobin A1c level and reported diabetes diagnosis. Hypertension was based on measured blood pressure and reported hypertension diagnosis. Results Individuals with undiagnosed diabetes compared with individuals without diabetes had lower grip strength (51.9 vs 69.8, p=0.0001), as well as among individuals with diagnosed diabetes compared with individuals without diabetes (61.7 vs 69.8, p=0.008). Mean grip strength was lower among individuals with undiagnosed hypertension compared with individuals without hypertension (63.5 vs 71.5, p=0.008) as well as among individuals with diagnosed hypertension compared with those without hypertension (60.8 vs 71.5, p<0.0001). In adjusted analyses controlling for age, sex, race, smoking status, and first-degree relative with disease, mean grip strength was lower for undiagnosed diabetes (β= −10.02, p<0.0001) and diagnosed diabetes (β= −8.21, p=0.03) compared with individuals without diabetes. In adjusted analyses, grip strength was lower among individuals with undiagnosed hypertension (β= −6.6, p=0.004) and diagnosed hypertension (β= −4.27, p=0.04) compared with individuals without hypertension. Conclusions Among healthy weight adults, combined grip strength is lower in individuals with diagnosed and undiagnosed diabetes and hypertension. PMID:26232901

Hand grip strength in the adult Malaysian population.

PubMed

Kamarul, T; Ahmad, T S; Loh, W Y C

2006-08-01

To measure the hand grip strength of Malaysians aged 18 to 65 years. Between January and April 2003, 412 subjects (200 women and 212 men) were recruited from staff, students, and visitors of the University of Malaya Medical Centre. Socioeconomic, general health, and lifestyle data were collected from each subject using a standard questionnaire. Weight and height were measured prior to testing. Standardised positioning and instructions based on several hand grip protocols were used. Data were collected using the LIDO kinetic work set. 93% of the subjects were right-hand dominant and 7% were left-hand dominant. Hand grip strength was significantly correlated with hand dominance, gender, occupation, height, and weight, but not body mass index. No significant differences in grip strength were noted with regard to race or level of income. Men were stronger than women in all age-groups, with a ratio of 1.75:1. In both right- and left-hand dominant groups, the dominant hand was consistently stronger than the non-dominant side, with a ratio of 1.12:1 in the right-hand dominant group and 1.05:1 in the left-hand dominant group. The strongest hand grip strength in the right-hand dominant group occurred in the age-group of 25 to 34 years; in the left-hand dominant group it was in the age-group of 18 to 24 years. In western populations, the mean grip strength can be as much as 1.5 times greater than in the Malaysian population. Data derived from western populations cannot be applied to a comparable Malaysian population. Gender, hand dominance, age, occupation, weight, and height must be considered when establishing normal values for grip strength.

Musician's dystonia is highly task specific: no strong evidence for everyday fine motor deficits in patients.

PubMed

Hofmann, Aurélie; Grossbach, Michael; Baur, Volker; Hermsdörfer, Joachim; Altenmüller, Eckart

2015-03-01

1) To examine the fine motor skills used everyday by patients suffering from musician's dystonia (MD) in the upper limb in order to verify whether MD is task-specific; and 2) to compare the affected and non-affected hands of MD musicians vs healthy musicians in performance of these tasks in order to clarify whether dystonic symptoms can be found in the non-affected side of MD patients. MD is typically considered to be focal and task specific, but patients often report impairment in everyday life activities. Furthermore, in the course of MD, about 15% of patients complain of dystonic symptoms in other parts of the body. Twenty-seven musicians affected by MD and 27 healthy musicians were studied using 1) the Motor Performance Test Series, 2) a kinematic analysis of handwriting, and 3) an assessment of the grip force regulation while lifting and moving a manipulandum. Patients performed most fine motor tasks without any evidence of a deficit. Exclusively in the handwriting tasks (2), they exhibited fewer frequencies of the written trace and a prolonged overall writing time. MD is highly task specific and does not strongly affect other motor skills. The subtle deficits in handwriting may be explained as a consequence of a general psychological disposition rather than as compensatory mechanisms to avoid the appearance of dystonic symptoms. Furthermore, we did not find signs of multifocal motor deficits in the unaffected hands of MD patients.

Development of an integrated digital hand grip dynamometer and norm of hand grip strength.

PubMed

Chang, Ho; Chen, Chih-Hao; Huang, Tung-Sun; Tai, Chun-Yen

2015-01-01

This study designs and fabricates a novel integrated digital hand grip dynamometer and analyzes collected grip strength data. The dynamometer directly stores collected data in a computer, unlike those on the market that cannot directly store information. A strain gauge load cell is used as a force sensor. The dynamometer is designed to maximize ergonomics. Excitation voltage of the load cell is 5 V, and a 9 V battery supplies power to its circuit. The signal receiver is National Instruments (NI) data acquisition (DAQ) card that transmits signals to the computer. The operation system is designed using LabView. This study assesses the correlation between variables of collected data. The correlation coefficients for height, weight and palm length were 0.793, 0.609 and 0.715, respectively, indicating that variables were moderately to strongly correlate with grip strength.

Quantitative assessment of motor fatigue: normative values and comparison with prior-polio patients.

PubMed

Meldrum, Dara; Cahalane, Eibhlis; Conroy, Ronan; Guthrie, Richard; Hardiman, Orla

2007-06-01

Motor fatigue is a common complaint of polio survivors and has a negative impact on activities of daily living. The aim of this study was to establish a normative database for hand grip strength and fatigue and to investigate differences between prior-polio subjects and normal controls. Static and dynamic hand grip fatigue and maximum voluntary isometric contraction (MVIC) of hand grip were measured in subjects with a prior history of polio (n = 44) and healthy controls (n = 494). A normative database of fatigue was developed using four indices of analysis. Compared with healthy controls, subjects with prior polio had significantly reduced hand grip strength but developed greater hand grip fatigue in only one fatigue index. Quantitative measurement of fatigue in the prior-polio population may be useful in order to detect change over time and to evaluate treatment strategies.

Precision pointing and control of flexible spacecraft

NASA Technical Reports Server (NTRS)

Bantell, M. H., Jr.

1987-01-01

The problem and long term objectives for the precision pointing and control of flexible spacecraft are given. The four basic objectives are stated in terms of two principle tasks. Under Task 1, robust low order controllers, improved structural modeling methods for control applications and identification methods for structural dynamics are being developed. Under Task 2, a lab test experiment for verification of control laws and system identification algorithms is being developed. For Task 1, work has focused on robust low order controller design and some initial considerations for structural modeling in control applications. For Task 2, work has focused on experiment design and fabrication, along with sensor selection and initial digital controller implementation. Conclusions are given.

Prognostic value of grip strength: findings from the Prospective Urban Rural Epidemiology (PURE) study.

PubMed

Leong, Darryl P; Teo, Koon K; Rangarajan, Sumathy; Lopez-Jaramillo, Patricio; Avezum, Alvaro; Orlandini, Andres; Seron, Pamela; Ahmed, Suad H; Rosengren, Annika; Kelishadi, Roya; Rahman, Omar; Swaminathan, Sumathi; Iqbal, Romaina; Gupta, Rajeev; Lear, Scott A; Oguz, Aytekin; Yusoff, Khalid; Zatonska, Katarzyna; Chifamba, Jephat; Igumbor, Ehimario; Mohan, Viswanathan; Anjana, Ranjit Mohan; Gu, Hongqiu; Li, Wei; Yusuf, Salim

2015-07-18

Reduced muscular strength, as measured by grip strength, has been associated with an increased risk of all-cause and cardiovascular mortality. Grip strength is appealing as a simple, quick, and inexpensive means of stratifying an individual's risk of cardiovascular death. However, the prognostic value of grip strength with respect to the number and range of populations and confounders is unknown. The aim of this study was to assess the independent prognostic importance of grip strength measurement in socioculturally and economically diverse countries. The Prospective Urban-Rural Epidemiology (PURE) study is a large, longitudinal population study done in 17 countries of varying incomes and sociocultural settings. We enrolled an unbiased sample of households, which were eligible if at least one household member was aged 35-70 years and if household members intended to stay at that address for another 4 years. Participants were assessed for grip strength, measured using a Jamar dynamometer. During a median follow-up of 4.0 years (IQR 2.9-5.1), we assessed all-cause mortality, cardiovascular mortality, non-cardiovascular mortality, myocardial infarction, stroke, diabetes, cancer, pneumonia, hospital admission for pneumonia or chronic obstructive pulmonary disease (COPD), hospital admission for any respiratory disease (including COPD, asthma, tuberculosis, and pneumonia), injury due to fall, and fracture. Study outcomes were adjudicated using source documents by a local investigator, and a subset were adjudicated centrally. Between January, 2003, and December, 2009, a total of 142,861 participants were enrolled in the PURE study, of whom 139,691 with known vital status were included in the analysis. During a median follow-up of 4.0 years (IQR 2.9-5.1), 3379 (2%) of 139,691 participants died. After adjustment, the association between grip strength and each outcome, with the exceptions of cancer and hospital admission due to respiratory illness, was similar across country-income strata. Grip strength was inversely associated with all-cause mortality (hazard ratio per 5 kg reduction in grip strength 1.16, 95% CI 1.13-1.20; p<0.0001), cardiovascular mortality (1.17, 1.11-1.24; p<0.0001), non-cardiovascular mortality (1.17, 1.12-1.21; p<0.0001), myocardial infarction (1.07, 1.02-1.11; p=0.002), and stroke (1.09, 1.05-1.15; p<0.0001). Grip strength was a stronger predictor of all-cause and cardiovascular mortality than systolic blood pressure. We found no significant association between grip strength and incident diabetes, risk of hospital admission for pneumonia or COPD, injury from fall, or fracture. In high-income countries, the risk of cancer and grip strength were positively associated (0.916, 0.880-0.953; p<0.0001), but this association was not found in middle-income and low-income countries. This study suggests that measurement of grip strength is a simple, inexpensive risk-stratifying method for all-cause death, cardiovascular death, and cardiovascular disease. Further research is needed to identify determinants of muscular strength and to test whether improvement in strength reduces mortality and cardiovascular disease. Full funding sources listed at end of paper (see Acknowledgments). Copyright © 2015 Elsevier Ltd. All rights reserved.

Generating human-like movements on an anthropomorphic robot using an interior point method

NASA Astrophysics Data System (ADS)

Costa e Silva, E.; Araújo, J. P.; Machado, D.; Costa, M. F.; Erlhagen, W.; Bicho, E.

2013-10-01

In previous work we have presented a model for generating human-like arm and hand movements on an anthropomorphic robot involved in human-robot collaboration tasks. This model was inspired by the Posture-Based Motion-Planning Model of human movements. Numerical results and simulations for reach-to-grasp movements with two different grip types have been presented previously. In this paper we extend our model in order to address the generation of more complex movement sequences which are challenged by scenarios cluttered with obstacles. The numerical results were obtained using the IPOPT solver, which was integrated in our MATLAB simulator of an anthropomorphic robot.

Subject-Specific Carpal Ligament Elongation in Extreme Positions, Grip, and the Dart Thrower's Motion

PubMed Central

Rainbow, Michael J.; Kamal, Robin N.; Moore, Douglas C.; Akelman, Edward; Wolfe, Scott W.; Crisco, Joseph J.

2015-01-01

This study examined whether the radiocarpal and dorsal capsular ligaments limit end-range wrist motion or remain strained during midrange wrist motion. Fibers of these ligaments were modeled in the wrists of 12 subjects over multiple wrist positions that reflect high demand tasks and the dart thrower's motion. We found that many of the volar and dorsal ligaments were within 5% of their maximum length throughout the range of wrist motion. Our finding of wrist ligament recruitment during midrange and end-range wrist motion helps to explain the complex but remarkably similar intersubject patterns of carpal motion. PMID:26367853

The influence of golf shaft stiffness on grip and clubhead kinematics.

PubMed

MacKenzie, Sasho J; Boucher, Daniel E

2017-01-01

The purpose of this study was to investigate the influence of shaft stiffness on grip and clubhead kinematics. Two driver shafts with disparate levels of stiffness, but very similar inertial properties, were tested by 33 golfers representing a range of abilities. Shaft deflection data as well as grip and clubhead kinematics were collected from 14 swings, with each shaft, for each golfer using an optical motion capture system. The more flexible shaft (R-Flex) demonstrated a higher contribution to clubhead speed from shaft deflection dynamics (P < .001), but was also associated with significantly less grip angular velocity at impact (P = .001), resulting in no significant difference in clubhead speed (P = .14). However, at the individual level, half of the participants demonstrated a significant difference in clubhead speed between shafts. The more flexible shaft was also associated with significantly different magnitudes of head rotation relative to the grip. More specifically, both bend loft (P < .001) and bend lie (P < .001) were greater for the R-Flex shaft, while bend close (P = .017) was greater for the stiffer (X-Flex) shaft. However, changes in grip orientation resulted in no significant differences in face orientation, between the shafts, at impact.

Attentional Focus and Grip Width Influences on Bench Press Resistance Training.

PubMed

Calatayud, Joaquin; Vinstrup, Jonas; Jakobsen, Markus D; Sundstrup, Emil; Colado, JuanCarlos; Andersen, Lars L

2018-04-01

This study evaluated the influence of different attentional foci for varied grip widths in the bench press. Eighteen resistance-trained men were familiarized with the procedure and performed a one-repetition maximum (1RM) test during Session 1. In Session 2, they used three different standardized grip widths (100%, 150%, and 200% of biacromial width distance) in random order at 50% of 1RM while also engaged in three different attention focus conditions (external focus on the bench press, internal focus on pectoralis major muscles, and internal focus on triceps brachii muscles). Surface electromyography (EMG) signals were recorded from the triceps brachii and pectoralis major, and peak EMG of the filtered signals were normalized to maximum EMG of each muscle. Both grip width and focus influenced the muscle activity level, but there were no significant interactions between these variables. Exploratory analyses suggested that an internal focus may slightly (4%-6%) increase pectoralis major activity at wider grip widths and triceps brachii activity at narrower grip widths, but this should be confirmed or rejected in a study with a larger sample size or through a meta-analysis of research to date.

[Gait speed, grip strength and self-rated health among the elderly: data from the FIBRA Campinas network, São Paulo, Brazil].

PubMed

Bez, Joelita Pessoa de Oliveira; Neri, Anita Liberalesso

2014-08-01

The article seeks to investigate patterns of performance and relationships between grip strength, gait speed and self-rated health, and investigate the relationships between them, considering the variables of gender, age and family income. This was conducted in a probabilistic sample of community-dwelling elderly aged 65 and over, members of a population study on frailty. A total of 689 elderly people without cognitive deficit suggestive of dementia underwent tests of gait speed and grip strength. Comparisons between groups were based on low, medium and high speed and strength. Self-related health was assessed using a 5-point scale. The males and the younger elderly individuals scored significantly higher on grip strength and gait speed than the female and oldest did; the richest scored higher than the poorest on grip strength and gait speed; females and men aged over 80 had weaker grip strength and lower gait speed; slow gait speed and low income arose as risk factors for a worse health evaluation. Lower muscular strength affects the self-rated assessment of health because it results in a reduction in functional capacity, especially in the presence of poverty and a lack of compensatory factors.

Comparison of pressure pain threshold, grip strength,dexterity and touch pressure of dominant and non-dominant hands within and between right-and left-handed subjects.

PubMed

Ozcan, Ayse; Tulum, Zeliha; Pinar, Lamia; Başkurt, Ferdi

2004-12-01

This study was done to evaluate differences in pressure pain threshold, grip strength, manual dexterity and touch pressure threshold in the dominant and non-dominant hands of right- and left-handed subjects, and to compare findings within and between these groups. Thirty-nine right-handed and twenty-one left-handed subjects participated in the study. Pressure pain threshold was assessed using a dolorimeter, grip strength was assessed with a hand-grip dynamometer, manual dexterity was evaluated using the VALPAR Component Work Sample-4 system, and touch pressure threshold was determined using Semmes Weinstein monofilaments. Results for the dominant and non-dominant hands were compared within and between the groups. In the right-handed subjects, the dominant hand was significantly faster with the VALPAR Component Work Sample-4, showed significantly greater grip strength, and had a significantly higher pressure pain threshold than the non-dominant hand. The corresponding results for the two hands were similar in the left-handed subjects. The study revealed asymmetrical manual performance in grip strength, manual dexterity and pressure pain threshold in right-handed subjects, but no such asymmetries in left-handed subjects.

Identification of Dynapenia in Older Adults Through the Use of Grip Strength T-Scores

PubMed Central

Bohannon, Richard W; Magasi, Susan

2014-01-01

Objective To generate reference values and t-scores (1.0 to 2.5 standard deviations below average) for grip strength for healthy young adults and to examine the utility of t-scores from this group for the identification of dynapenia in older adults. Design Secondary analysis of cross-sectional grip strength data from the NIH Toolbox norming sample. Setting Population-based general community sample. Participants Community dwelling adults, between the ages 20 and 40 years (n=558); and 60 to 85 years (n=390) Main Outcomes Measures Grip strength measured with a Jamar plus dynamometer. Results Maximum grip strengths were consistent over the 20–40 year age span. For men they were 108.0 lbs (S.D. 22.6). For women, they were 65.8 lbs (S.D. 14.6) Comparison of older participant grip strengths to those of the younger reference group revealed (depending on age strata) that 46.2–87.1% of older men and 50.0–82.4% of older women could be designated as dynapenic on the basis of t-scores. Conclusion The use of reference value t-scores from younger adults is a promising method for determining dynapenia in older adults. PMID:24729356

Identification of dynapenia in older adults through the use of grip strength t-scores.

PubMed

Bohannon, Richard W; Magasi, Susan

2015-01-01

The aim of this study was to generate reference values and t-scores (1.0-2.5 standard deviations below average) for grip strength for healthy young adults and to examine the utility of t-scores from this group for the identification of dynapenia in older adults. Our investigation was a population-based, general community secondary analysis of cross-sectional grip strength data utilizing the NIH Toolbox Assessment norming sample. Participants consisted of community-dwelling adults, with age ranges of 20-40 years (n = 558) and 60-85 years (n = 390). The main outcome measure was grip strength using a Jamar plus dynamometer. Maximum grip strengths were consistent over the 20-40-year age group [men 108.0 (SD 22.6) pounds, women 65.8 (SD 14.6) pounds]. Comparison of older group grip strengths to those of the younger reference group revealed (depending on age strata) that 46.2-87.1% of older men and 50.0-82.4% of older women could be designated as dynapenic on the basis of t-scores. The use of reference value t-scores from younger adults is a promising method for determining dynapenia in older adults. © 2014 Wiley Periodicals, Inc.

Cutting moments and grip forces in meat cutting operations and the effect of knife sharpness.

PubMed

McGorry, Raymond W; Dowd, Peter C; Dempsey, Patrick G

2003-07-01

The force exposure associated with meat cutting operations and the effect of knife sharpness on performance and productivity have not been well documented. Specialized hardware was used to measure grip force and reactive moments with 15 professional meat cutters performing lamb shoulder boning, beef rib trimming and beef loin trim operations in a field study conducted in two meat packing plants. A system for measuring relative blade sharpness was developed for this study. Mean and peak cutting moments observed for the meat cutting operations, averaged across subjects were 4.7 and 17.2 Nm for the shoulder boning, 3.5 and 12.9 Nm for the rib trim, and 2.3 and 10.6 Nm for the loin trim, respectively. Expressed as percent of MVC, mean grip forces of 28.3% and peak grip forces of 72.6% were observed overall. Blade sharpness was found to effect grip forces, cutting moments and cutting time, with sharper blades requiring statistically significantly lower peak and mean cutting moments, and grip forces than dull knives. Efforts aimed at providing and maintaining sharp blades could have a significant impact on force exposure.

A shared, flexible neural map architecture reflects capacity limits in both visual short-term memory and enumeration.

PubMed

Knops, André; Piazza, Manuela; Sengupta, Rakesh; Eger, Evelyn; Melcher, David

2014-07-23

Human cognition is characterized by severe capacity limits: we can accurately track, enumerate, or hold in mind only a small number of items at a time. It remains debated whether capacity limitations across tasks are determined by a common system. Here we measure brain activation of adult subjects performing either a visual short-term memory (vSTM) task consisting of holding in mind precise information about the orientation and position of a variable number of items, or an enumeration task consisting of assessing the number of items in those sets. We show that task-specific capacity limits (three to four items in enumeration and two to three in vSTM) are neurally reflected in the activity of the posterior parietal cortex (PPC): an identical set of voxels in this region, commonly activated during the two tasks, changed its overall response profile reflecting task-specific capacity limitations. These results, replicated in a second experiment, were further supported by multivariate pattern analysis in which we could decode the number of items presented over a larger range during enumeration than during vSTM. Finally, we simulated our results with a computational model of PPC using a saliency map architecture in which the level of mutual inhibition between nodes gives rise to capacity limitations and reflects the task-dependent precision with which objects need to be encoded (high precision for vSTM, lower precision for enumeration). Together, our work supports the existence of a common, flexible system underlying capacity limits across tasks in PPC that may take the form of a saliency map. Copyright © 2014 the authors 0270-6474/14/349857-10$15.00/0.

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…

Stress examination of flexor tendon pulley rupture in the crimp grip position: a 1.5-Tesla MRI cadaver study.

PubMed

Bayer, Thomas; Fries, Simon; Schweizer, Andreas; Schöffl, Isabelle; Janka, Rolf; Bongartz, Georg

2015-01-01

The objectives of this study were the evaluation of flexor tendon pulley rupture of the fingers in the crimp grip position using magnetic resonance imaging (MRI) and the comparison of the results with MRI in the neutral position in a cadaver study. MRI in the crimp grip position and in the neutral position was performed in 21 cadaver fingers with artificially created flexor tendon pulley tears (combined pulley rupture, n = 14; single pulley rupture, n = 7). Measurement of the distance between the tendon and bone was performed. Images were evaluated by two readers, first independently and in cases of discrepancy in consensus. Sensitivity and specificity for detecting combined pulley ruptures were calculated. Tendon bone distances were significantly higher in the crimp grip position than in the neutral position. Sensitivity and specificity for detecting combined pulley rupture were 92.86 % and 100 % respectively in the crimp grip position and 78.57 % and 85.71 % respectively in the neutral position. Kappa values for interobserver reliability were 0.87 in the crimp grip position and 0.59 in the neutral position. MRI examination in the crimp grip position results in higher tendon bone distances by subjecting the pulleys to a higher strain, which facilitates image evaluation with higher interobserver reliability, higher sensitivity, and higher specificity for combined pulley rupture compared with examination in the neutral position.

Validation of a pictorial rating scale for grip strength evaluation in 3- to 6-year-old children.

PubMed

Defrasne Ait-Said, Elise; Groslambert, Alain; Courty, Daniel

2007-06-13

The present study aimed to validate a pictorial rating scale to evaluate the child's ability to produce grip forces. Thirty-seven children aged 3 to 6 years participated as subjects in this investigation. We used a tailor-made pictorial scale and a hand grip strength meter, as well as a Piaget's clinical interview aimed to gather information on the child's understanding of the rating scale. The sensitivity of the rating scale was measured by testing a 4-intensity-level hand grip effort with 3- to 6-year-old children. In addition, the reproducibility of this pictorial rating scale was investigated by a test and randomised re-test procedure. Statistical analysis revealed that no significant main effect (P>0.05) for test was observed in any child. In addition, no significant main effect (P>0.05) for intensity was found in 3-year-old children. However, in the 4-year-old children and over, a significant main effect (P<0.05) was found for intensity. The results also showed that 5- and 6-year-old children were able to produce four differentiated intensities of grip forces. These findings suggest that the pictorial rating scale for grip strength evaluation showed acceptable reproducibility and was sensitive to the age of the children tested. To conclude, this pictorial rating scale appears to be a valid tool to investigate accurately the child's ability to produce grip forces in young children from 5-year-old and over.

The influences of obesity and age on functional performance during intermittent upper extremity tasks.

PubMed

Cavuoto, Lora A; Nussbaum, Maury A

2014-01-01

In this study, the main and interactive effects of obesity and age on functional performance were assessed during intermittent exertions involving the upper extremity. The prevalence of obesity has doubled over the past 30 years and this increase is associated with higher health care costs, rates of workplace injury, and lost workdays. Obesity and aging can modify job demands and affect worker capacity in terms of muscular and psychomotor function. However, there is a lack of empirical studies quantifying the work-relevant (or ergonomic) impacts related to task demands, capacities, and their potential imbalance. Eight obese and eight non-obese participants from each of two age groups (18-25 and 50-65 years) completed three endurance tasks involving fixed levels of task demands: hand grip, shoulder flexion, and a simulated assembly task using the upper extremity. Measures of functional performance including endurance, discomfort, motor control, and task performance were recorded for each of the task conditions. Endurance times were ∼60% longer for the non-obese group, and older participants had longer endurance times; however there was no evidence of interactive effects of obesity and age. Obesity also impaired functional performance, as indicated by higher rates of strength loss, increases in discomfort, and declines in task performance. These observed impairments may reflect underlying physiological differences among individuals who are obese, but that are independent of age. Obesity-related impairments may have implications for the design of work duration and demand level to prevent fatigue development for workers who are obese.

Changes in performance over time while learning to use a myoelectric prosthesis

PubMed Central

2014-01-01

Background Training increases the functional use of an upper limb prosthesis, but little is known about how people learn to use their prosthesis. The aim of this study was to describe the changes in performance with an upper limb myoelectric prosthesis during practice. The results provide a basis to develop an evidence-based training program. Methods Thirty-one able-bodied participants took part in an experiment as well as thirty-one age- and gender-matched controls. Participants in the experimental condition, randomly assigned to one of four groups, practiced with a myoelectric simulator for five sessions in a two-weeks period. Group 1 practiced direct grasping, Group 2 practiced indirect grasping, Group 3 practiced fixating, and Group 4 practiced a combination of all three tasks. The Southampton Hand Assessment Procedure (SHAP) was assessed in a pretest, posttest, and two retention tests. Participants in the control condition performed SHAP two times, two weeks apart with no practice in between. Compressible objects were used in the grasping tasks. Changes in end-point kinematics, joint angles, and grip force control, the latter measured by magnitude of object compression, were examined. Results The experimental groups improved more on SHAP than the control group. Interestingly, the fixation group improved comparable to the other training groups on the SHAP. Improvement in global position of the prosthesis leveled off after three practice sessions, whereas learning to control grip force required more time. The indirect grasping group had the smallest object compression in the beginning and this did not change over time, whereas the direct grasping and the combination group had a decrease in compression over time. Moreover, the indirect grasping group had the smallest grasping time that did not vary over object rigidity, while for the other two groups the grasping time decreased with an increase in object rigidity. Conclusions A training program should spend more time on learning fine control aspects of the prosthetic hand during rehabilitation. Moreover, training should start with the indirect grasping task that has the best performance, which is probably due to the higher amount of useful information available from the sound hand. PMID:24568148

Decoding Information for Grasping from the Macaque Dorsomedial Visual Stream.

PubMed

Filippini, Matteo; Breveglieri, Rossella; Akhras, M Ali; Bosco, Annalisa; Chinellato, Eris; Fattori, Patrizia

2017-04-19

Neurodecoders have been developed by researchers mostly to control neuroprosthetic devices, but also to shed new light on neural functions. In this study, we show that signals representing grip configurations can be reliably decoded from neural data acquired from area V6A of the monkey medial posterior parietal cortex. Two Macaca fascicularis monkeys were trained to perform an instructed-delay reach-to-grasp task in the dark and in the light toward objects of different shapes. Population neural activity was extracted at various time intervals on vision of the objects, the delay before movement, and grasp execution. This activity was used to train and validate a Bayes classifier used for decoding objects and grip types. Recognition rates were well over chance level for all the epochs analyzed in this study. Furthermore, we detected slightly different decoding accuracies, depending on the task's visual condition. Generalization analysis was performed by training and testing the system during different time intervals. This analysis demonstrated that a change of code occurred during the course of the task. Our classifier was able to discriminate grasp types fairly well in advance with respect to grasping onset. This feature might be important when the timing is critical to send signals to external devices before the movement start. Our results suggest that the neural signals from the dorsomedial visual pathway can be a good substrate to feed neural prostheses for prehensile actions. SIGNIFICANCE STATEMENT Recordings of neural activity from nonhuman primate frontal and parietal cortex have led to the development of methods of decoding movement information to restore coordinated arm actions in paralyzed human beings. Our results show that the signals measured from the monkey medial posterior parietal cortex are valid for correctly decoding information relevant for grasping. Together with previous studies on decoding reach trajectories from the medial posterior parietal cortex, this highlights the medial parietal cortex as a target site for transforming neural activity into control signals to command prostheses to allow human patients to dexterously perform grasping actions. Copyright © 2017 the authors 0270-6474/17/374311-12$15.00/0.

Visual context modulates potentiation of grasp types during semantic object categorization.

PubMed

Kalénine, Solène; Shapiro, Allison D; Flumini, Andrea; Borghi, Anna M; Buxbaum, Laurel J

2014-06-01

Substantial evidence suggests that conceptual processing of manipulable objects is associated with potentiation of action. Such data have been viewed as evidence that objects are recognized via access to action features. Many objects, however, are associated with multiple actions. For example, a kitchen timer may be clenched with a power grip to move it but pinched with a precision grip to use it. The present study tested the hypothesis that action evocation during conceptual object processing is responsive to the visual scene in which objects are presented. Twenty-five healthy adults were asked to categorize object pictures presented in different naturalistic visual contexts that evoke either move- or use-related actions. Categorization judgments (natural vs. artifact) were performed by executing a move- or use-related action (clench vs. pinch) on a response device, and response times were assessed as a function of contextual congruence. Although the actions performed were irrelevant to the categorization judgment, responses were significantly faster when actions were compatible with the visual context. This compatibility effect was largely driven by faster pinch responses when objects were presented in use-compatible, as compared with move-compatible, contexts. The present study is the first to highlight the influence of visual scene on stimulus-response compatibility effects during semantic object processing. These data support the hypothesis that action evocation during conceptual object processing is biased toward context-relevant actions.

Visual context modulates potentiation of grasp types during semantic object categorization

PubMed Central

Kalénine, Solène; Shapiro, Allison D.; Flumini, Andrea; Borghi, Anna M.; Buxbaum, Laurel J.

2013-01-01

Substantial evidence suggests that conceptual processing of manipulable objects is associated with potentiation of action. Such data have been viewed as evidence that objects are recognized via access to action features. Many objects, however, are associated with multiple actions. For example, a kitchen timer may be clenched with a power grip to move it, but pinched with a precision grip to use it. The present study tested the hypothesis that action evocation during conceptual object processing is responsive to the visual scene in which objects are presented. Twenty-five healthy adults were asked to categorize object pictures presented in different naturalistic visual contexts that evoke either move- or use-related actions. Categorization judgments (natural vs. artifact) were performed by executing a move- or use-related action (clench vs. pinch) on a response device, and response times were assessed as a function of contextual congruence. Although the actions performed were irrelevant to the categorization judgment, responses were significantly faster when actions were compatible with the visual context. This compatibility effect was largely driven by faster pinch responses when objects were presented in use- compared to move-compatible contexts. The present study is the first to highlight the influence of visual scene on stimulus-response compatibility effects during semantic object processing. These data support the hypothesis that action evocation during conceptual object processing is biased toward context-relevant actions. PMID:24186270

Flexible Electrostatic Technology for Capture and Handling Project

NASA Technical Reports Server (NTRS)

Keys, Andrew; Bryan, Tom; Horwitz, Chris; Rakoczy, John; Waggoner, Jason

2015-01-01

To NASA unfunded & planned missions: This new capability to sense proximity, flexibly align to, and attractively grip and capture practically any object in space without any pre-designed physical features or added sensors or actuators will enable or enhance many of MSFC's strategic emphasis areas in space transportation, and space systems such as: 1. A Flexible Electrostatic gripper can enable the capture, gripping and releasing of an extraterrestrial sample of different minerals or a sample canister (metallic or composite) without requiring a handle or grapple fixture.(B) 2. Flexible self-aligning in-space capture/soft docking or berthing of ISS resupply vehicles, pressurized modules, or nodes for in-space assembly and shielding, radiator, and solar Array deployment for space habitats (C) 3. The flexible electrostatic gripper when combined with a simple steerable extendible boom can grip, position, and release objects of various shapes and materials with low mass and power without any prior handles or physical accommodations or surface contamination for ISS experiment experiments and in-situ repair.(F)(G) 4. The Dexterous Docking concept previously proposed to allow simple commercial resupply ships to station-keep and capture either ISS or an Exploration vehicle for supply or fluid transfer lacked a self-sensing, compliant, soft capture gripper like FETCH that could retract and attach to a CBM. (I) 5. To enable a soft capture and de-orbit of a piece of orbital debris will require self-aligning gripping and holding an object wherever possible (thermal coverings or shields of various materials, radiators, solar arrays, antenna dishes) with little or no residual power while adding either drag or active low level thrust.(K) 6. With the scalability of the FETCH technology, small satellites can be captured and handled or can incorporate FETCH gripper to dock to and handle other small vehicles and larger objects for de-orbiting or mitigating Orbital debris (L) 7. Many of previous MSFC and NASA proposals or concepts can now be realized or simplified by the development of the this initial and future FETCH grippers including commercial resupply, Exploration vehicle assembly, Satellite servicing, and orbital debris removal since a major part of these missions is to align to and capture some handle. Completed Project (2013 - 2014) Flexible Electrostatic Technology for Capture & Handling Project Center Innovation Fund: MSFC CIF Program | Space Technology Mission Directorate (STMD) For more information visit techport.nasa.gov Some NASA technology projects are smaller (for example SBIR/STTR, NIAC and Center Innovation Fund), and will have less content than other, larger projects. Newly created projects may not sensors or injection of permanent adhesives. With gripping forces estimated between 0.5 and 2.5 pounds per square inch or 70-300 lb./sq. ft. of surface contact, the FETCH can turn-on and turn-off rapidly and repeatedly to enable sample handling, soft docking, in-space assembly, and precision relocation for accurate anchor adhesion.

Age-Related and Sex-Related Differences in Hand and Pinch Grip Strength in Adults

ERIC Educational Resources Information Center

Puh, Urska

2010-01-01

The purpose of the study was to quantify age-related changes in hand grip strength and three types of pinch grip strength (key pinch, tip pinch, and palmar pinch) among male and female participants. The study included 199 healthy participants (100 females, 99 males) aged 20-79 years, who were divided into four age groups. The Baseline Hydraulic…

GRIP Experiment 2010

NASA Image and Video Library

2010-08-15

The NASA DC-8 airplane sits on the tarmac, Monday, Aug. 16, 2010, at Fort Lauderdale Hollywood International Airport in Fort Lauderdale, Fla. , as preparations continue for its part in the GRIP experiment. The Genesis and Rapid Intensification Processes (GRIP) experiment is a NASA Earth science field experiment in 2010 that is being conducted to better understand how tropical storms form and develop into major hurricanes. Photo Credit: (NASA/Paul E. Alers)

GRIP Experiment 2010

NASA Image and Video Library

2010-08-14

The NASA DC-8 airplane sits on the tarmac, Sunday, Aug. 15, 2010, at Fort Lauderdale International Airport in Fort Lauderdale, Fla. , as preparations continue for its part in the GRIP experiment. The Genesis and Rapid Intensification Processes (GRIP) experiment is a NASA Earth science field experiment in 2010 that is being conducted to better understand how tropical storms form and develop into major hurricanes. Photo Credit: (NASA/Paul E. Alers)

Energy efficiency analysis of the manipulation process by the industrial objects with the use of Bernoulli gripping devices

NASA Astrophysics Data System (ADS)

Savkiv, Volodymyr; Mykhailyshyn, Roman; Duchon, Frantisek; Mikhalishin, Mykhailo

2017-11-01

The article deals with the topical issue of reducing energy consumption for transportation of industrial objects. The energy efficiency of the process of objects manipulation with the use of the orientation optimization method while gripping with the help of different methods has been studied. The analysis of the influence of the constituent parts of inertial forces, that affect the object of manipulation, on the necessary force characteristics and energy consumption of Bernoulli gripping device has been proposed. The economic efficiency of the use of the optimal orientation of Bernoulli gripping device while transporting the object of manipulation in comparison to the transportation without re-orientation has been proved.

Self-gripping mesh versus fibrin glue fixation in laparoscopic inguinal hernia repair: a randomized prospective clinical trial in young and elderly patients

PubMed Central

Bindi, Marco; Rivelli, Matteo; Solej, Mario; Enrico, Stefano; Martino, Valter

2016-01-01

Abstract Laparoscopic transabdominal preperitoneal inguinal hernia repair is a safe and effective technique. In this study we tested the hypothesis that self-gripping mesh used with the laparoscopic approach is comparable to polypropylene mesh in terms of perioperative complications, against a lower overall cost of the procedure. We carried out a prospective randomized trial comparing a group of 30 patients who underwent laparoscopic inguinal hernia repair with self-gripping mesh versus a group of 30 patients who received polypropylene mesh with fibrin glue fixation. There were no statistically significant differences between the two groups with regard to intraoperative variables, early or late intraoperative complications, chronic pain or recurrence. Self-gripping mesh in transabdominal hernia repair was found to be a valid alternative to polypropylene mesh in terms of complications, recurrence and postoperative pain. The cost analysis and comparability of outcomes support the preferential use of self-gripping mesh. PMID:28352842

The transcriptional coregulator GRIP1 controls macrophage polarization and metabolic homeostasis

PubMed Central

Coppo, Maddalena; Chinenov, Yurii; Sacta, Maria A.; Rogatsky, Inez

2016-01-01

Diet-induced obesity causes chronic macrophage-driven inflammation in white adipose tissue (WAT) leading to insulin resistance. WAT macrophages, however, differ in their origin, gene expression and activities: unlike infiltrating monocyte-derived inflammatory macrophages, WAT-resident macrophages counteract inflammation and insulin resistance, yet, the mechanisms underlying their transcriptional programming remain poorly understood. We recently reported that a nuclear receptor cofactor—glucocorticoid receptor (GR)-interacting protein (GRIP)1—cooperates with GR to repress inflammatory genes. Here, we show that GRIP1 facilitates macrophage programming in response to IL4 via a GR-independent pathway by serving as a coactivator for Kruppel-like factor (KLF)4—a driver of tissue-resident macrophage differentiation. Moreover, obese mice conditionally lacking GRIP1 in macrophages develop massive macrophage infiltration and inflammation in metabolic tissues, fatty livers, hyperglycaemia and insulin resistance recapitulating metabolic disease. Thus, GRIP1 is a critical regulator of immunometabolism, which engages distinct transcriptional mechanisms to coordinate the balance between macrophage populations and ultimately promote metabolic homeostasis. PMID:27464507

Wearable flex sensor system for multiple badminton player grip identification

NASA Astrophysics Data System (ADS)

Jacob, Alvin; Zakaria, Wan Nurshazwani Wan; Tomari, Mohd Razali Bin Md; Sek, Tee Kian; Suberi, Anis Azwani Muhd

2017-09-01

This paper focuses on the development of a wearable sensor system to identify the different types of badminton grip that is used by a player during training. Badminton movements and strokes are fast and dynamic, where most of the involved movement are difficult to identify with the naked eye. Also, the usage of high processing optometric motion capture system is expensive and causes computational burden. Therefore, this paper suggests the development of a sensorized glove using flex sensor to measure a badminton player's finger flexion angle. The proposed Hand Monitoring Module (HMM) is connected to a personal computer through Bluetooth to enable wireless data transmission. The usability and feasibility of the HMM to identify different grip types were examined through a series of experiments, where the system exhibited 70% detection ability for the five different grip type. The outcome plays a major role in training players to use the proper grips for a badminton stroke to achieve a more powerful and accurate stroke execution.

Automated assembly in space

NASA Technical Reports Server (NTRS)

Srivastava, Sandanand; Dwivedi, Suren N.; Soon, Toh Teck; Bandi, Reddy; Banerjee, Soumen; Hughes, Cecilia

1989-01-01

The installation of robots and their use of assembly in space will create an exciting and promising future for the U.S. Space Program. The concept of assembly in space is very complicated and error prone and it is not possible unless the various parts and modules are suitably designed for automation. Certain guidelines are developed for part designing and for an easy precision assembly. Major design problems associated with automated assembly are considered and solutions to resolve these problems are evaluated in the guidelines format. Methods for gripping and methods for part feeding are developed with regard to the absence of gravity in space. The guidelines for part orientation, adjustments, compliances and various assembly construction are discussed. Design modifications of various fasteners and fastening methods are also investigated.

Sex Differences in Fear of Falling among Older Adults with Low Grip Strength.

PubMed

Lim, Eunju

2016-05-01

Fear of falling is not only a risk factor for falls, but it is also an important clinical predictor of functional decline in older adults. This study identified sex differences in fear of falling and related factors in older adults with low grip strength. The data of 902 older adults from the 2012 Korean National Survey, conducted as a research project by the Korea Employment Information Service, were analyzed. Grip strength, activities of daily living, cognitive function, depressive symptoms, and fear of falling were assessed. Multiple regression analysis was performed by a simultaneous data entry method. Fear of falling was greater in older women with low grip strength than in their male equivalents (P<0.001). Regression analysis showed that age, fall experience within the previous 2 yr, activities of daily living, and depressive symptoms collectively accounted for 15.3% (P<0.001) of the variance among men. Meanwhile, age, fall experience within the previous 2 yr, grip strength, activities of daily living, and depressive symptoms collectively accounted for 13.4% (P<0.001) of the variance among women. Thus, the predictors of fear of falling differ between older men and women with low grip strength. Therefore, sex differences must be considered when developing intervention strategies for reducing fear of falling in this demographic.

Early reduction in toe flexor strength is associated with physical activity in elderly men.

PubMed

Suwa, Masataka; Imoto, Takayuki; Kida, Akira; Yokochi, Takashi

2016-05-01

[Purpose] To compare the toe flexor, hand grip and knee extensor strengths of young and elderly men, and to examine the association between toe flexor strength and physical activity or inactivity levels. [Subjects and Methods] Young (n=155, 18-23 years) and elderly (n=60, 65-88 years) men participated in this study. Toe flexor, hand grip, and knee extensor strength were measured. Physical activity (time spent standing/walking per day) and inactivity (time spent sitting per day) were assessed using a self-administered questionnaire. [Results] Toe flexor, hand grip, and knee extensor strength of the elderly men were significantly lower than those of the young men. Standing/walking and sitting times of the elderly men were lower than those of the young men. Toe flexor strength correlated with hand grip and knee extensor strength in both groups. In elderly men, toe flexor strength correlated with standing/walking time. In comparison to the young men's mean values, toe flexor strength was significantly lower than knee extensor and hand grip strength in the elderly group. [Conclusion] The results suggest that age-related reduction in toe flexor strength is greater than those of hand grip and knee extensor strengths. An early loss of toe flexor strength is likely associated with reduced physical activity in elderly men.

Sustainable Cooperative Robotic Technologies for Human and Robotic Outpost Infrastructure Construction and Maintenance

NASA Technical Reports Server (NTRS)

Stroupe, Ashley W.; Okon, Avi; Robinson, Matthew; Huntsberger, Terry; Aghazarian, Hrand; Baumgartner, Eric

2004-01-01

Robotic Construction Crew (RCC) is a heterogeneous multi-robot system for autonomous acquisition, transport, and precision mating of components in construction tasks. RCC minimizes resources constrained in a space environment such as computation, power, communication and, sensing. A behavior-based architecture provides adaptability and robustness despite low computational requirements. RCC successfully performs several construction related tasks in an emulated outdoor environment despite high levels of uncertainty in motions and sensing. Quantitative results are provided for formation keeping in component transport, precision instrument placement, and construction tasks.

Bilateral robotic priming before task-oriented approach in subacute stroke rehabilitation: a pilot randomized controlled trial.

PubMed

Hsieh, Yu-Wei; Wu, Ching-Yi; Wang, Wei-En; Lin, Keh-Chung; Chang, Ku-Chou; Chen, Chih-Chi; Liu, Chien-Ting

2017-02-01

To investigate the treatment effects of bilateral robotic priming combined with the task-oriented approach on motor impairment, disability, daily function, and quality of life in patients with subacute stroke. A randomized controlled trial. Occupational therapy clinics in medical centers. Thirty-one subacute stroke patients were recruited. Participants were randomly assigned to receive bilateral priming combined with the task-oriented approach (i.e., primed group) or to the task-oriented approach alone (i.e., unprimed group) for 90 minutes/day, 5 days/week for 4 weeks. The primed group began with the bilateral priming technique by using a bimanual robot-aided device. Motor impairments were assessed by the Fugal-Meyer Assessment, grip strength, and the Box and Block Test. Disability and daily function were measured by the modified Rankin Scale, the Functional Independence Measure, and actigraphy. Quality of life was examined by the Stroke Impact Scale. The primed and unprimed groups improved significantly on most outcomes over time. The primed group demonstrated significantly better improvement on the Stroke Impact Scale strength subscale ( p = 0.012) and a trend for greater improvement on the modified Rankin Scale ( p = 0.065) than the unprimed group. Bilateral priming combined with the task-oriented approach elicited more improvements in self-reported strength and disability degrees than the task-oriented approach by itself. Further large-scale research with at least 31 participants in each intervention group is suggested to confirm the study findings.

Functional Status Modifies the Association of Blood Pressure with Death in Elders: Health and Retirement Study.

PubMed

Wu, Chenkai; Smit, Ellen; Peralta, Carmen A; Sarathy, Harini; Odden, Michelle C

2017-07-01

To examine whether grip strength, gait speed, and the combination of the two physical functioning measures modified the association of systolic BP (SBP) and diastolic BP (DBP) with mortality. Nationally representative cohort study. Health and Retirement Study. 7,492 U.S. adults aged ≥65 years. Grip strength was measured by a hand dynamometer and classified as normal (≥16 kg for female; ≥26 kg for male) and weak. Gait speed was assessed over a 98.5-inch walk and classified as non-slow (≥0.60 m/s for female; ≥0.52 m/s for male) and slow. Over an average follow-up time of 6.0 years, 1,870 (25.0%) participants died. After adjustment for socio-demographic, behavioral, and clinical measures, elevated SBP (≥150 mmHg) and DBP (≥90 mmHg) was associated with a 24% (95% CI, 7-43%) and 25% (95% CI, 5-49%) higher mortality among participants with normal grip strength. In contrast, elevated SBP and DBP was associated with a 6% (95% CI, 31 to -27%) and a 16% (95% CI, 46 to -26%) lower mortality among those with weak grip strength (P-values of interactions: both=.07). The inverse relations between BP with death were most pronounced among slow walkers with weak grip strength. The HRs of elevated SBP and DBP for death was 0.85 (95% CI, 0.56-1.29) and 0.53 (95% CI, 0.30-0.96), respectively, and was substantially different from non-slow walkers with normal grip strength (HR = 1.24 and 1.15, respectively; P-values of interactions: both <.001). Therefore, associations of BP with death varied modestly by gait speed. Grip strength modified the association of BP with death. Combination of grip strength and gait speed has incremental value for modifying the association of BP with death. © 2017, Copyright the Authors Journal compilation © 2017, The American Geriatrics Society.

Grip strength as a frailty diagnostic component in geriatric inpatients.

PubMed

Dudzińska-Griszek, Joanna; Szuster, Karolina; Szewieczek, Jan

2017-01-01

Frailty has emerged as a key medical syndrome predictive of comorbidity, disability, institutionalization and death. As a component of the five frailty phenotype diagnostic criteria, patient grip strength deserves attention as a simple and objective measure of the frailty syndrome. The aim of this study was to assess conditions that influence grip strength in geriatric inpatients. The study group consisted of 80 patients aged 78.6±7.0 years [Formula: see text], with 68.8% women, admitted to the Department of Geriatrics. A comprehensive geriatric assessment was complemented with assessment for the frailty phenotype as described by Fried et al for all patients in the study group. Functional assessment included Barthel Index of Activities of Daily Living (Barthel Index), Instrumental Activities of Daily Living Scale and Mini-Mental State Examination. Three or more frailty criteria were positive in 32 patients (40%), while 56 subjects (70%) fulfilled the frailty criterion of weakness (grip strength test). Multivariate linear regression analysis revealed that two independent measures showed positive association with grip strength - Mini-Mental State Examination score (β=0.239; P =0.001) and statin use (β=0.213; P =0.002) - and four independent measures were negatively associated with grip strength - female sex (β=-0.671; P <0.001), C-reactive protein (β=-0.253; P <0.001), prior myocardial infarction (β=-0.190; P =0.006) and use of an antidepressant (β=-0.163; P =0.018). Low physical activity was identified as the only independent qualitative frailty component associated with 2-year mortality in multivariate logistic regression analysis after adjustment for age and sex (odds ratio =6.000; 95% CI =1.357-26.536; P =0.018). Cognitive function, somatic comorbidity and medical treatment affect grip strength as a measure of physical frailty in geriatric inpatients. Grip strength was not predictive of 2-year mortality in this group.

Birth weight, intrauterine growth restriction and nutritional status in childhood in relation to grip strength in adults: from the 1982 Pelotas (Brazil) birth cohort.

PubMed

Bielemann, Renata Moraes; Gigante, Denise Petrucci; Horta, Bernardo Lessa

2016-02-01

The aim of this study was to evaluate the association among birth weight, intrauterine growth, and nutritional status in childhood with grip strength in young adults from the 1982 Pelotas (Brazil) birth cohort. In 1982, the hospital live births of Pelotas were followed. In 2012, grip strength was evaluated using a hand dynamometer and the best of the six measurements was used. Birth weight was analyzed as z-score for gestational age according to Williams (1982) curve. Weight-for-age, weight-for-length/height, and length/height-for-age at 2 and 4 y were analyzed in z-scores according to 2006 World Health Organization Child Growth Standards. Lean mass at 30 y was included as possible mediator using the g-computation formula. In 2012, 3701 (68.1%) individuals were interviewed and 3470 were included in the present analyses. An increase of 1 z-score in birth weight was associated with an increase of 1.5 kg in grip strength in males (95% confidence interval, 1.1-1.9). Positive effect of birth weight on grip strength was found in females. Grip strength was greater in individuals who were born with appropriate size for gestational age and positively associated with weight- and length/height-for-age z-score at 2 and 4 y of age. A positive association between birth weight and grip strength was only partially mediated by adult lean mass (50% and 33% of total effect in males and females), whereas direct effect of weight at 2 y was found only in males. It is suggested that good nutrition in prenatal and early postnatal life has a positive influence on adult muscle strength. The results from birth weight were suggestive of fetal programming on grip strength measurement. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Location versus task relevance: The impact of differing internal focus of attention instructions on motor performance.

PubMed

Pelleck, Valerie; Passmore, Steven R

2017-05-01

Impaired performance while executing a motor task is attributed to a disruption of normal automatic processes when an internal focus of attention is used. What remains unclear is whether the specificity of internally focused task instructions may impact task performance. The present study assessed the implications of changing the attentional focus of novice and skilled golfers by measuring behavioural, neurophysiological and kinematic changes during a golf putting task. Over six blocks of ten putting trials each, attention was directed either externally (towards the target) or internally in one of two ways: 1) proximal (keeping the elbows extended and the hands gripping the putter); or 2) distal (keeping the weight evenly distributed between both legs) to the critical elements of the task. Results provided evidence that when novice participants use an internal focus of attention more closely associated with task performance that their: 1) execution; 2) accuracy; 3) variability of surface electromyography (sEMG) activity; and 4) kinematics of the putter movement are all adversely affected. Skilled golfers are much more resilient to changes in attentional focus, while all participants interpret a distal internal focus of attention similar to an external focus. All participants produced decreased activity in the muscle (tibialis anterior) associated with the distal (less task relevant) focus of attention even when the "internal" focus was on the lower extremity. Our results provide evidence that the skill level of the participant and the distance of the internal focus of attention from the key elements of a motor skill directly impact the execution, muscle activity, and movement kinematics associated with skilled motor task performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Memory for a single object has differently variable precisions for relevant and irrelevant features.

PubMed

Swan, Garrett; Collins, John; Wyble, Brad

2016-01-01

Working memory is a limited resource. To further characterize its limitations, it is vital to understand exactly what is encoded about a visual object beyond the "relevant" features probed in a particular task. We measured the memory quality of a task-irrelevant feature of an attended object by coupling a delayed estimation task with a surprise test. Participants were presented with a single colored arrow and were asked to retrieve just its color for the first half of the experiment before unexpectedly being asked to report its direction. Mixture modeling of the data revealed that participants had highly variable precision on the surprise test, indicating a coarse-grained memory for the irrelevant feature. Following the surprise test, all participants could precisely recall the arrow's direction; however, this improvement in direction memory came at a cost in precision for color memory even though only a single object was being remembered. We attribute these findings to varying levels of attention to different features during memory encoding.

Beta-Adrenergic Modulation of Tremor and Corticomuscular Coherence in Humans

PubMed Central

Baker, Mark R.; Baker, Stuart N.

2012-01-01

Coherence between the bioelectric activity of sensorimotor cortex and contralateral muscles can be observed around 20 Hz. By contrast, physiological tremor has a dominant frequency around 10 Hz. Although tremor has multiple sources, it is partly central in origin, reflecting a component of motoneuron discharge at this frequency. The motoneuron response to ∼20 Hz descending input could be altered by non-linear interactions with ∼10 Hz motoneuron firing. We investigated this further in eight healthy human subjects by testing the effects of the beta-adrenergic agents propranolol (non-selective β-antagonist) and salbutamol (β2-agonist), which are known to alter the size of physiological tremor. Corticomuscular coherence was assessed during an auxotonic precision grip task; tremor was quantified using accelerometry during index finger extension. Experiments with propranolol used a double-blind, placebo-controlled crossover design. A single oral dose of propranolol (40 mg) significantly increased beta band (15.3–32.2 Hz) corticomuscular coherence compared with placebo, but reduced tremor in the 6.2–11.9 Hz range. Salbutamol (2.5 mg) was administered by inhalation. Whilst salbutamol significantly increased tremor amplitude as expected, it did not change corticomuscular coherence. The opposite direction of the effects of propranolol on corticomuscular coherence and tremor, and the fact that salbutamol enhances tremor but does not affect coherence, implies that the magnitude of corticomuscular coherence is little influenced by non-linear interactions with 10 Hz oscillations in motoneurons or the periphery. Instead, we suggest that propranolol and salbutamol may affect both tremor and corticomuscular coherence partly via a central site of action. PMID:23185297

Functional sensibility assessment. Part II: Effects of sensory improvement on precise pinch force modulation after transverse carpal tunnel release.

PubMed

Hsu, Hsiu-Yun; Kuo, Li-Chieh; Chiu, Haw-Yen; Jou, I-Ming; Su, Fong-Chin

2009-11-01

Patients with median nerve compression at the carpal tunnel often have poor sensory afferents. Without adequate sensory modulation control, these patients frequently exhibit clumsy performance and excessive force output in the affected hand. We analyzed precision grip function after the sensory recovery of patients with carpal tunnel syndrome (CTS) who underwent carpal tunnel release (CTR). Thirteen CTS patients were evaluated using a custom-designed pinch device and conventional sensory tools before and after CTR to measure sensibility, maximum pinch strength, and anticipated pinch force adjustments to movement-induced load fluctuations in a pinch-holding-up activity. Based on these tests, five force-related parameters and sensory measurements were used to determine improvements in pinch performance after sensory recovery. The force ratio between the exerted pinch force and maximum load force of the lifting object was used to determine pinch force coordination and to prove that CTR enabled precision motor output. The magnitude of peak pinch force indicated an economic force output during manipulations following CTR. The peak pinch force, force ratio, and percentage of maximum pinch force also demonstrated a moderate correlation with the Semmes-Weinstein test. Analysis of these tests revealed that improved sensory function helped restore patients' performance in precise pinch force control evaluations. These results suggest that sensory information plays an important role in adjusting balanced force output in dexterous manipulation. (c) 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

GRIP Experiment 2010

NASA Image and Video Library

2017-12-08

The NASA DC-8 airplane sits on the tarmac, Sunday, Aug. 15, 2010, at Fort Lauderdale International Airport in Fort Lauderdale, Fla. , as preparations continue for its part in the GRIP experiment. The Genesis and Rapid Intensification Processes (GRIP) experiment is a NASA Earth science field experiment in 2010 that is being conducted to better understand how tropical storms form and develop into major hurricanes. Credit: NASA/Paul E. Alers To read more about the GRIP Mission go here or here for an interactive feature NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

Robot Hand Grips Cylinders Securely

NASA Technical Reports Server (NTRS)

Parma, George F.

1989-01-01

Jaws and linkage accommodate various sizes. Robot hand includes two pairs of parallel jaws that grasp rods, pipes, tubes, struts, and other long, heavy cylindrical objects. Hand features compact rotary drive and butterfly configuration simplifying approach and gripping maneuvers of robot. Parallelogram linkages maintain alignment of each jaw with other jaws. One bar of each linkage connected to one of two concentric, counterrotating shafts; rotation of shafts moves jaws in each pair toward or away from each other to grasp or release workpiece. Each jaw includes rigid gripping pad lined with rubber to give firm grip and to prevent damage to workpiece. Inner cylindrical surface (corner) of each jaw tapers off to flat sides. Enables jaw to grasp workpieces with diameters larger than or equal to twice the corner radius.

The effect of lower body stabilization and different writing tools on writing biomechanics in children with cerebral palsy.

PubMed

Cheng, Hsin-Yi Kathy; Lien, Yueh-Ju; Yu, Yu-Chun; Ju, Yan-Ying; Pei, Yu-Cheng; Cheng, Chih-Hsiu; Wu, David Bin-Chia

2013-04-01

A high percentage of children with cerebral palsy (CP) have difficulty keeping up with the handwriting demands at school. Previous studies have addressed the effects of proper sitting and writing tool on writing performance, but less on body biomechanics. The aim of this study was to investigate the influence of lower body stabilization and pencil design on body biomechanics in children with CP. Fourteen children (12.31±4.13 years old) with CP were recruited for this study. A crossover repeated measures design was employed, with two independent variables: lower body stabilization (with/without) and pencil (regular/assigned grip height/biaxial). The writing task was to trace the Archimedean spiral mazes. Electromyography (EMG) of the upper extremity, the wrist flexion/extension movements, and the whole body photography were recorded to quantify the changes in posture and upper extremity biomechanics. Two-way repeated measures ANOVA was used for statistical analysis. No significant main effects were revealed in the EMG and wrist kinematics. The lower body stabilization significantly decreased the trunk lateral and forward deviations, and the visual focus-vertical angle. The biaxial pencil and the assigned grip height design significantly decreased the head, shoulder, trunk, and pelvic deviations compared with the regular design. The results indicated that the lower body positioning was effective in improving the trunk posture. A pencil with an assigned grip height or with a biaxial design could improve head, shoulder, trunk and pelvic alignment, but did not influence the muscle exertion of the upper extremity. This study could provide guidelines for parents, teachers and clinicians regarding the selection of writing tools and the knowledge of proper positioning for the children with handwriting difficulties. Further analyses can focus on the design, modification and clinical application of assitive sitting and writing devices for the use in children with handwriting difficulties. Copyright © 2013 Elsevier Ltd. All rights reserved.

Is the Hierarchy of Loss in Functional Ability Evident in Midlife? Findings from a British Birth Cohort.

PubMed

Wloch, Elizabeth G; Kuh, Diana; Cooper, Rachel

2016-01-01

Difficulties performing a range of physical tasks of daily living have been shown to develop in older populations in a typically observed sequence, known as the hierarchy of loss. Nearly all previous research has been undertaken using populations aged over 75. This study aimed to use cross-sectional and longitudinal data to test for evidence of the hierarchy of loss from midlife onwards. The prevalence of reported difficulty undertaking 16 physical tasks in the MRC National Survey of Health and Development at age 60-64 were calculated, with Mokken scaling used to confirm the hierarchical order. Logistic regression was used to calculate the odds ratios of reporting difficulty performing tasks at the bottom of the hierarchy (i.e. feeding, washing and/or toileting) at age 60-64 by reported difficulty at the top of the hierarchy (i.e. gripping, walking and/or stair climbing) at age 43. At age 60-64, tasks associated with balance, strength and co-ordination, such as climbing stairs, were the first tasks participants reported difficulty with and tasks associated with upper limb mobility, such as feeding yourself, were the last. In a fully-adjusted model, participants who reported difficulty at the top of the hierarchy at age 43 were 2.85 (95% CI: 1.45-5.60) times more likely to report difficulty with tasks at the bottom of the hierarchy at age 60-64. This study presents evidence of the hierarchy of loss in a younger population than previously observed suggesting that targeted interventions to prevent functional decline should not be delayed until old age.

Impact of simulated three-dimensional perception on precision of depth judgements, technical performance and perceived workload in laparoscopy.

PubMed

Sakata, S; Grove, P M; Hill, A; Watson, M O; Stevenson, A R L

2017-07-01

This study compared precision of depth judgements, technical performance and workload using two-dimensional (2D) and three-dimensional (3D) laparoscopic displays across different viewing distances. It also compared the accuracy of 3D displays with natural viewing, along with the relationship between stereoacuity and 3D laparoscopic performance. A counterbalanced within-subjects design with random assignment to testing sequences was used. The system could display 2D or 3D images with the same set-up. A Howard-Dolman apparatus assessed precision of depth judgements, and three laparoscopic tasks (peg transfer, navigation in space and suturing) assessed performance (time to completion). Participants completed tasks in all combinations of two viewing modes (2D, 3D) and two viewing distances (1 m, 3 m). Other measures administered included the National Aeronautics and Space Administration Task Load Index (perceived workload) and the Randot ® Stereotest (stereoacuity). Depth judgements were 6·2 times as precise at 1 m and 3·0 times as precise at 3 m using 3D versus 2D displays (P < 0·001). Participants performed all laparoscopic tasks faster in 3D at both 1 and 3 m (P < 0.001), with mean completion times up to 64 per cent shorter for 3D versus 2D displays. Workload was lower for 3D displays (up to 34 per cent) than for 2D displays at both viewing distances (P < 0·001). Greater viewing distance inhibited performance for two laparoscopic tasks, and increased perceived workload for all three (P < 0·001). Higher stereoacuity was associated with shorter completion times for the navigating in space task performed in 3D at 1 m (r = - 0·40, P = 0·001). 3D displays offer large improvements over 2D displays in precision of depth judgements, technical performance and perceived workload. © 2017 The Authors. BJS published by John Wiley & Sons Ltd on behalf of BJS Society Ltd.

Dissociations of the number and precision of visual short-term memory representations in change detection.

PubMed

Xie, Weizhen; Zhang, Weiwei

2017-11-01

The present study dissociated the number (i.e., quantity) and precision (i.e., quality) of visual short-term memory (STM) representations in change detection using receiver operating characteristic (ROC) and experimental manipulations. Across three experiments, participants performed both recognition and recall tests of visual STM using the change-detection task and the continuous color-wheel recall task, respectively. Experiment 1 demonstrated that the estimates of the number and precision of visual STM representations based on the ROC model of change-detection performance were robustly correlated with the corresponding estimates based on the mixture model of continuous-recall performance. Experiments 2 and 3 showed that the experimental manipulation of mnemonic precision using white-noise masking and the experimental manipulation of the number of encoded STM representations using consolidation masking produced selective effects on the corresponding measures of mnemonic precision and the number of encoded STM representations, respectively, in both change-detection and continuous-recall tasks. Altogether, using the individual-differences (Experiment 1) and experimental dissociation (Experiment 2 and 3) approaches, the present study demonstrated the some-or-none nature of visual STM representations across recall and recognition.

Criterion-Referenced Values of Grip Strength and Usual Gait Speed Using Instrumental Activities of Daily Living Disability as the Criterion.

PubMed

Lee, Meng-Chih; Hsu, Chih-Cheng; Tsai, Yi-Fen; Chen, Ching-Yu; Lin, Cheng-Chieh; Wang, Ching-Yi

Current evidence suggests that grip strength and usual gait speed (UGS) are important predictors of instrumental activities of daily living (IADL) disability. Knowing the optimum cut points of these tests for discriminating people with and without IADL disability could help clinicians or researchers to better interpret the test results and make medical decisions. The purpose of this study was to determine the cutoff values of grip strength and UGS for best discriminating community-dwelling older adults with and without IADL disability, separately for men and women, and to investigate their association with IADL disability. We conducted secondary data analysis on a national dataset collected in the Sarcopenia and Translational Aging Research in Taiwan (START). The data used in this study consisted of health data of 2420 community-dwelling older adults 65 years and older with no history of stroke and with complete data. IADL disability was defined as at least 1 IADL item scored as "need help" or "unable to perform." Receiver operating characteristics analysis was used to estimate the optimum grip strength and UGS cut points for best discriminating older adults with/without IADL disability. The association between each physical performance (grip strength and UGS) and IADL disability was assessed with odds ratios (ORs). With IADL disability as the criterion, the optimal cutoff values of grip strength were 28.7 kg for men and 16.0 kg for women, and those for UGS were 0.76 m/s for men and 0.66 m/s for women. The grip strength test showed satisfactory discriminant validity (area under the curve > 0.7) in men and a strong association with IADL disability (OR > 4). Our cut points using IADL disability as the criterion were close to those indicating frailty or sarcopenia. Our reported cutoffs can serve as criterion-referenced values, along with those previously determined using different indicators, and provide important landmarks on the performance continua of older adults' grip strength and UGS. These landmarks could be useful in interpreting test results, monitoring changes in performance, and identifying individuals requiring timely intervention. For identifying older adults at risk of IADL disability, grip strength is superior to UGS.

The Effect of Two Different Hand Exercises on Grip Strength, Forearm Circumference, and Vascular Maturation in Patients Who Underwent Arteriovenous Fistula Surgery

PubMed Central

Kong, Sangwon; Lee, Kyung Soo; Kim, Junho

2014-01-01

Objective To compare the effect of two different hand exercises on hand strength and vascular maturation in patients who underwent arteriovenous fistula surgery. Methods We recruited 18 patients who had chronic kidney disease and had undergone arteriovenous fistula surgery for hemodialysis. After the surgery, 10 subjects performed hand-squeezing exercise with GD Grip, and other 8 subjects used Soft Ball. The subjects continued the exercises for 4 weeks. The hand grip strength, pinch strength (tip, palmar and lateral pinch), and forearm circumference of the subjects were assessed before and after the hand-squeezing exercise. The cephalic vein size, blood flow velocity and volume were also measured by ultrasonography in the operated limb. Results All of the 3 types of pinch strengths, grip strength, and forearm circumference were significantly increased in the group using GD Grip. Cephalic vein size and blood flow volume were also significantly increased. However, blood flow velocity showed no difference after the exercise. The group using Soft Ball showed a significant increase in the tip and lateral pinch strength and forearm circumference. The cephalic vein size and blood flow volume were also significantly increased. On comparing the effect of the two different hand exercises, hand-squeezing exercise with GD Grip had a significantly better effect on the tip and palmar pinch strength than hand-squeezing exercise with Soft Ball. The effect on cephalic vein size was not significantly different between the two groups. Conclusion The results showed that hand squeezing exercise with GD Grip was more effective in increasing the tip and palmar pinch strength compared to hand squeezing exercise with soft ball. PMID:25379494

Structural insight into GRIP1-PDZ6 in Alzheimer's disease: study from protein expression data to molecular dynamics simulations.

PubMed

Chatterjee, Paulami; Roy, Debjani

2017-08-01

Protein-protein interaction domain, PDZ, plays a critical role in efficient synaptic transmission in brain. Dysfunction of synaptic transmission is thought to be the underlying basis of many neuropsychiatric and neurodegenerative disorders including Alzheimer's disease (AD). In this study, Glutamate Receptor Interacting Protein1 (GRIP1) was identified as one of the most important differentially expressed, topologically significant proteins in the protein-protein interaction network. To date, very few studies have analyzed the detailed structural basis of PDZ-mediated protein interaction of GRIP1. In order to gain better understanding of structural and dynamic basis of these interactions, we employed molecular dynamics (MD) simulations of GRIP1-PDZ6 dimer bound with Liprin-alpha and GRIP1-PDZ6 dimer alone each with 100 ns simulations. The analyses of MD simulations of Liprin-alpha bound GRIP1-PDZ6 dimer show considerable conformational differences than that of peptide-free dimer in terms of SASA, hydrogen bonding patterns, and along principal component 1 (PC1). Our study also furnishes insight into the structural attunement of the PDZ6 domains of Liprin-alpha bound GRIP1 that is attributed by significant shift of the Liprin-alpha recognition helix in the simulated peptide-bound dimer compared to the crystal structure and simulated peptide-free dimer. It is evident that PDZ6 domains of peptide-bound dimer show differential movements along PC1 than that of peptide-free dimers. Thus, Liprin-alpha also serves an important role in conferring conformational changes along the dimeric interface of the peptide-bound dimer. Results reported here provide information that may lead to novel therapeutic approaches in AD.

Normative static grip strength of population of Turkey, effects of various factors and a comparison with international norms.

PubMed

Ekşioğlu, Mahmut

2016-01-01

Normative data are of importance in ergonomics and clinical settings. Applying normative data internationally is questionable. To this end, this study aimed to establish gender- and age-specific reference values for static (isometric) hand grip strength of normal population of Turkey with special regard to occupational demand, and compare them with the international norms. The secondary aims were to investigate the effects of gender, age-group, weight-group, job-group, hand and several anthropometric variables on static grip strength. A sample of 211 (128 male and 83 female) volunteers aged between 18 and 69 with various occupations participated in the study. Grip strength data were collected using a Jamar dynamometer with standard testing position, protocol and instructions. The mean and std deviation of maximum voluntary static grip strength values (in N) for dominant and non-dominant hands respectively were 455.2 ± 73.6 and 441.5 ± 72.6 for males, and 258 ± 46.1 and 246.2 ± 49.1 for females. The mean female strength was about 57% of the mean male strength value for both dominant and non-dominant hands. There was a curvilinear relationship of grip strength to age, significant differences between genders, hands, and some age-groups, and a correlation to height, body-mass, BMI and hand dimensions depending on the gender. The comparisons with the norms of other world populations indicate that there are cross-national grip strength variations among some nations but not all. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

[Evaluation of grip strength in normal and obese Wistar rats submitted to swimming with overload after median nerve compression].

PubMed

Coradinia, Josinéia Gresele; Kakihata, Camila Mayumi Martin; Kunz, Regina Inês; Errero, Tatiane Kamada; Bonfleur, Maria Lúcia; Bertolini, Gladson Ricardo Flor

2015-01-01

To verify the functionality through muscle grip strength in animals with obesity induced by monosodium glutamate (MSG) and in control animals, which suffered compression of the right median nerve, and treated with swimming with overload. During the first five days of life, neonatal Wistar rats received subcutaneous injections of MSG. The control group received a hypertonic saline solution. Forty-eight rats were divided into six groups: G1 (control); G2 (control + injury); G3 (control + injury + swimming); G4 (obese); G5 (obese + injury); G6 (obese + injury + swimming). The animals in groups G2, G3, G5 and G6 were submitted to compression of the median nerve and G3 and G6 groups were treated, after injury, with swimming exercise with load for three weeks. The swimming exercise had a progressive duration, according to the week, of 20, 30 and 40minutes. Muscle strength was assessed using a grip strength meter preoperatively and on the 3rd, 7th, 14th and 21st days after surgery. The results were expressed and analyzed using descriptive and inferential statistics. When the grip strength was compared among assessments regardless of group, in the second assessment the animals exhibited lower grip strength. G1 and G4 groups had greater grip strength, compared to G2, G3, G4 and G6. The swimming exercise with overload has not been effective in promoting improvement in muscle grip strength after compression injury of the right median nerve in control and in obese-MSG rats. Copyright © 2013 Elsevier Editora Ltda. All rights reserved.

Analysis of force profile during a maximum voluntary isometric contraction task.

PubMed

Househam, Elizabeth; McAuley, John; Charles, Thompson; Lightfoot, Timothy; Swash, Michael

2004-03-01

This study analyses maximum voluntary isometric contraction (MVIC) and its measurement by recording the force profile during maximal-effort, 7-s hand-grip contractions. Six healthy subjects each performed three trials repeated at short intervals to study variation from fatigue. These three trials were performed during three separate sessions at daily intervals to look at random variation. A pattern of force development during a trial was identified. An initiation phase, with or without an initiation peak, was followed by a maintenance phase, sometimes with secondary pulses and an underlying decline in force. Of these three MVIC parameters, maximum force during the maintenance phase showed less random variability compared to intertrial fatigue variability than did maximum force during the initiation phase or absolute maximum force. Analysis of MVIC as a task, rather than a single, maximal value reveals deeper levels of motor control in its generation. Thus, force parameters other than the absolute maximum force may be better suited to quantification of muscle performance in health and disease.

Repetitive strain disorder: towards diagnostic criteria.

PubMed Central

Bird, H A; Hill, J

1992-01-01

Thirteen women (mean age 48.2 years; range 25-60 years) all of whom had developed musculoskeletal symptoms during employment in an industrial job with repetitive tasks were referred by their trade unions for adjudication on the cause of symptoms. One had rheumatoid arthritis. A study of the other 12 women provided an opportunity to document the natural history of repetitive strain disorder. Early symptoms of weakness were diffuse but were always relieved by rest. Several months later localisation of symptoms at a tendon, nerve, or enthesis could be predicted from the analysis of the action required in the particular repetitive task. Six of the 12 women required an operation several years later, thus providing histological confirmation of the presence of a lesion. Early loss of grip strength measured by a sphygmomanometer cuff compared with an unaffected control subject and improved by rest may be the most valuable sign in excluding compensation neurosis. The estimated prevalence of repetitive strain disorder defined by these strict criteria was at least 2% in conveyor belt workers. PMID:1417124

Effects of motor imagery and action observation on hand grip strength, electromyographic activity and intramuscular oxygenation in the hand gripping gesture: A randomized controlled trial.

PubMed

Losana-Ferrer, Alejandro; Manzanas-López, Sergio; Cuenca-Martínez, Ferran; Paris-Alemany, Alba; La Touche, Roy

2018-04-01

The aim of this study was to evaluate the effects of motor imagery and action observation combined with a hand grip strength program on the forearm muscles. Sixty subjects were selected and randomized into three groups: motor imagery (n = 20), action observation (n = 20), or a control group (n = 20). Outcome measures included hand grip strength, electromyographical activity and intramuscular oxygenation. The hand grip strength significantly increased in the motor imagery (p < .001) and action observation (p < .001) groups compared with the control group, although there were no differences between the both groups (p = .30). In the electromyographical activity, intra-group significant differences were found in motor imagery (p = .002) and action observation (p = .003) groups, although there were no differences between the both groups (p = 1.00) Intramuscular oxygenation results did not show any statistically significant differences between any of the study groups (p > .05). Our results suggest that both motor imagery and action observation training, combined with a hand grip strength program, present a significant strength gain and significant change in the strength and electromyographical activity of the forearm muscles, however no change was found in intramuscular oxygenation. Copyright © 2018 Elsevier B.V. All rights reserved.

Grip Strength as an Indicator of Health-Related Quality of Life in Old Age-A Pilot Study.

PubMed

Musalek, Christina; Kirchengast, Sylvia

2017-11-24

Over the last century life expectancy has increased dramatically nearly all over the world. This dramatic absolute and relative increase of the old aged people component of the population has influenced not only population structure but also has dramatic implications for the individuals and public health services. The aim of the present pilot study was to examine the impact of physical well-being assessed by hand grip strength and social factors estimated by social contact frequency on health-related quality of life among 22 men and 41 women ranging in age between 60 and 94 years. Physical well-being was estimated by hand grip strength, data concerning subjective wellbeing and health related quality of life were collected by personal interviews based on the WHOQOL-BREF questionnaires. Number of offspring and intergenerational contacts were not related significantly to health-related quality of life, while social contacts with non-relatives and hand grip strength in contrast had a significant positive impact on health related quality of life among old aged men and women. Physical well-being and in particular muscle strength-estimated by grip strength-may increase health-related quality of life and is therefore an important source for well-being during old age. Grip strength may be used as an indicator of health-related quality of life.

Grip pressure distributions and associated variability in golf: a two-club comparison.

PubMed

Langlais, Sean M; Broker, Jeffrey P

2014-06-01

Teaching and playing professionals offer multiple theories concerning the manner in which forces should be applied to the handle of the club during the golf swing. This study extends recent research concerning grip pressures and forces in golf, with the purpose of exploring the similarities and differences between force profiles for a 7-iron and driver swung by proficient golfers. A secondary purpose was to further analyze the way that golfers use grip forces to manipulate the club. Grip forces were measured on eight low handicap golfers (USGA indexes 0 to 7) swinging their own 7-irons and drivers. In total, lead-hand and trail-hand grip forces were isolated as well as anatomically specific forces within the hands. Force profile variability across multiple swings for each golfer and between golfers characterized consistencies and important differences. Correlations between 7-iron and driver force profiles characterized force 'signatures.' The data highlight large fluctuations in grip forces during the swing. Marked differences between participants were observed, involving force magnitudes and phasing. Dominant forces arose primarily from the lead hand, specifically the last three fingers. Force profiles were highly repeatable across swings for a golfer (standard deviations < 7% of total force) and force profile correlations between 7-iron and driver for a golfer were remarkably high (r2 = 0.86). Notably, within swing force variability was greatest during club acceleration, but dramatically decreased at impact.

GRIP Collaboration Portal: Information Management for a Hurricane Field Campaign

NASA Astrophysics Data System (ADS)

Conover, H.; Kulkarni, A.; Garrett, M.; Smith, T.; Goodman, H. M.

2010-12-01

NASA’s Genesis and Rapid Intensification Processes (GRIP) experiment, carried out in August and September of 2010, was a complex operation, involving three aircraft and their crews based at different airports, a dozen instrument teams, mission scientists, weather forecasters, project coordinators and a variety of other participants. In addition, GRIP was coordinated with concurrent airborne missions: NOAA’s IFEX and then NSF-funded PREDICT. The GRIP Collaboration Portal was developed to facilitate communication within and between the different teams and serve as an information repository for the field campaign, providing a single access point for project documents, plans, weather forecasts, flight reports and quicklook data. The portal was developed using the Drupal open source content management framework. This presentation will cover both technology and participation issues. Specific examples include: Drupal’s large and diverse open source developer community is an advantage in that we were able to reuse many modules rather than develop capabilities from scratch, but integrating multiple modules developed by many people adds to the overall complexity of the site. Many of the communication capabilities provided by the site, such as discussion forums and blogs, were not used. Participants were diligent about posting necessary documents, but the favored communication method remained email. Drupal's developer-friendly nature allowed for quick development of the customized functionality needed to accommodate the rapidly changing requirements of GRIP experiment. DC-8 Overflight of Hurricane Earl during GRIP Mission

Early reduction in toe flexor strength is associated with physical activity in elderly men

PubMed Central

Suwa, Masataka; Imoto, Takayuki; Kida, Akira; Yokochi, Takashi

2016-01-01

[Purpose] To compare the toe flexor, hand grip and knee extensor strengths of young and elderly men, and to examine the association between toe flexor strength and physical activity or inactivity levels. [Subjects and Methods] Young (n=155, 18–23 years) and elderly (n=60, 65–88 years) men participated in this study. Toe flexor, hand grip, and knee extensor strength were measured. Physical activity (time spent standing/walking per day) and inactivity (time spent sitting per day) were assessed using a self-administered questionnaire. [Results] Toe flexor, hand grip, and knee extensor strength of the elderly men were significantly lower than those of the young men. Standing/walking and sitting times of the elderly men were lower than those of the young men. Toe flexor strength correlated with hand grip and knee extensor strength in both groups. In elderly men, toe flexor strength correlated with standing/walking time. In comparison to the young men’s mean values, toe flexor strength was significantly lower than knee extensor and hand grip strength in the elderly group. [Conclusion] The results suggest that age-related reduction in toe flexor strength is greater than those of hand grip and knee extensor strengths. An early loss of toe flexor strength is likely associated with reduced physical activity in elderly men. PMID:27313353

HEAVY MANUAL WORK THROUGHOUT THE WORKING LIFETIME AND MUSCLE STRENGTH AMONG MEN AT RETIREMENT AGE

PubMed Central

Walker-Bone, K; D’Angelo, S; Syddall, HE; Palmer, KT; Cooper, C; Coggon, D; Sayer, AA

2016-01-01

Introduction Reductions in heavy manual work as a consequence of mechanisation might impact adversely on muscle strength at older ages. We investigated the association between grip strength at retirement age and lifetime occupational exposure to physically demanding activities. Grip strength is an important predictor of long-term health and physical function in older people. Methods Grip strength (maximum of three readings in each hand) was measured in men from the Hertfordshire Cohort Study at a single examination when their mean age was 65.8 (SD 2.9) years. Associations with lifetime occupational exposure (ascertained by questionnaire) to three activities (standing/walking ≥4 hours/day; lifting ≥25 kg; and energetic work sufficient to induce sweating) were assessed by multivariable linear regression with adjustment for various potential confounders. Results Complete data were available from 1,418 men who had worked for at least 20 years. After adjustment for age, height and weight, those with longer exposures to walking/standing and heavy lifting had lower grip strength, but the relationship disappeared after further adjustment for confounders. Working at physical intensity sufficient to induce sweating was not significantly associated with grip strength. Conclusions We found no evidence that physically demanding occupational activities increase hand grip strength at normal retirement age. Any advantages of regular physical occupational activity may have been obscured by unmeasured socio-economic confounders. PMID:26896253

Test-retest intra-rater reliability of grip force in patients with stroke.

PubMed

Hammer, Ann; Lindmark, Birgitta

2003-07-01

Coefficients of repeatability and reproducibility can be guides in differentiating between real changes and measurement error. The aim was to evaluate test-retest intra-rater reliability of a clinical procedure measuring grip force with Grippit in stroke patients, to assess relationship between grip force of the hands and between sustained and peak grip force. Eighteen patients were tested using the Grippit at two occasions one hour apart. Each occasion comprised three consecutive trials per hand. The paretic hand needs to score a 50 N change within and between occasions to exceed the measurement error in 95% of the observations, irrespective of calculation method. Expressed by CV(within) the measurement error was 10%. There was no learning or fatigue effect during measuring. There was a wide variation between subjects but the mean ratio between sides was 0.66. The mean ratio between sustained and peak grip force was 0.80-0.84. The measurement errors were acceptable and the instrument can be recommended for the use in stroke patients at a department of rehabilitation medicine.

Impact of a daily 10-minute strength and flexibility program in a manufacturing plant.

PubMed

Pronk, S J; Pronk, N P; Sisco, A; Ingalls, D S; Ochoa, C

1995-01-01

In summary, employees' flexibility and mood showed modest improvements following the implementation of a plant-wide, 10-minute, daily flexibility and strength program. The initial six-week pilot study, administered prior to the plant-wide program implementation, successfully assessed program feasibility, assessed the efficiency of program implementation, identified administrative and logistical concerns, and generated pilot data needed to secure managerial support. Despite the noted significant increases in grip strength in the pilot study, no increases were observed following the six months of plant-wide implementation. This may be related to the differences in low average pretest grip strength for the pilot study compared to the higher scores for the main study population. The pilot study subjects may have received a sufficient exercise stimulus to increase grip strength over the course of six weeks. In contrast, this may not have been the case for the main study subjects due to their higher initial mean grip strength. An increased number of exercises designed to directly impact grip strength may be needed to improve this parameter.

Developing Baby Bag Design by Using Kansei Engineering Method

NASA Astrophysics Data System (ADS)

Janari, D.; Rakhmawati, A.

2016-01-01

Consumer's preferences and market demand are essential factors for product's success. Thus, in achieving its success, a product should have design that could fulfill consumer's expectation. Purpose of this research is accomplishing baby bag product as stipulated by Kansei. The results that represent Kanseiwords are; neat, unique, comfortable, safe, modern, gentle, elegant, antique, attractive, simple, spacious, creative, colorful, durable, stylish, smooth and strong. Identification value on significance of correlation for durable attribute is 0,000 < 0,005, which means significant to baby's bag. While the value of coefficient regression is 0,812 < 0,005, which means that durable attribute insignificant to baby's bag.The result of the baby's bag final design selectionbased on the questionnaire 3 is resulting the combination of all design. Space for clothes, diaper's space, shoulder grip, side grip, bottle's heater pocket and bottle's pocket are derived from design 1. Top grip, space for clothes, shoulder grip, and side grip are derived from design 2.Others design that were taken are, spaces for clothes from design 3, diaper's space and clothes’ space from design 4.

Force Myography to Control Robotic Upper Extremity Prostheses: A Feasibility Study

PubMed Central

Cho, Erina; Chen, Richard; Merhi, Lukas-Karim; Xiao, Zhen; Pousett, Brittany; Menon, Carlo

2016-01-01

Advancement in assistive technology has led to the commercial availability of multi-dexterous robotic prostheses for the upper extremity. The relatively low performance of the currently used techniques to detect the intention of the user to control such advanced robotic prostheses, however, limits their use. This article explores the use of force myography (FMG) as a potential alternative to the well-established surface electromyography. Specifically, the use of FMG to control different grips of a commercially available robotic hand, Bebionic3, is investigated. Four male transradially amputated subjects participated in the study, and a protocol was developed to assess the prediction accuracy of 11 grips. Different combinations of grips were examined, ranging from 6 up to 11 grips. The results indicate that it is possible to classify six primary grips important in activities of daily living using FMG with an accuracy of above 70% in the residual limb. Additional strategies to increase classification accuracy, such as using the available modes on the Bebionic3, allowed results to improve up to 88.83 and 89.00% for opposed thumb and non-opposed thumb modes, respectively. PMID:27014682

Lessons Learned from Pit Viper System Deployment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Catalan, Michael A.; Alzheimer, James M.; Valdez, Patrick LJ

2002-04-11

Tele-operated and robotic systems operated in unstructured field environments pose unique challenges for tool design. Since field tasks are not always well defined and the robot work area usually cannot be designed for ease of operation, the tools must be versatile. It's important to carefully consider the orientation of the grip the robot takes on the tool, as it's not easily changed in the field. The stiffness of the robot and the possibility of robot positioning errors encourages the use of non-contact or minimal-contact tooling. While normal hand tools can usually be modified for use by the robot, this ismore » not always the most effective approach. It's desirable to have tooling that is relatively independent of the robot; in this case, the robot places the tool near the desired work location and the tool performs its task relatively independently. Here we consider the adaptation of a number of tools for cleanup of a radioactively contaminated piping junction and valve pit. The tasks to be considered are debris removal (small nuts and bolts and pipe up to 100 mm in diameter), size reduction, surface cleaning, and support of past practice crane-based methods for working in the pits.« less

The effects of selective and divided attention on sensory precision and integration.

PubMed

Odegaard, Brian; Wozny, David R; Shams, Ladan

2016-02-12

In our daily lives, our capacity to selectively attend to stimuli within or across sensory modalities enables enhanced perception of the surrounding world. While previous research on selective attention has studied this phenomenon extensively, two important questions still remain unanswered: (1) how selective attention to a single modality impacts sensory integration processes, and (2) the mechanism by which selective attention improves perception. We explored how selective attention impacts performance in both a spatial task and a temporal numerosity judgment task, and employed a Bayesian Causal Inference model to investigate the computational mechanism(s) impacted by selective attention. We report three findings: (1) in the spatial domain, selective attention improves precision of the visual sensory representations (which were relatively precise), but not the auditory sensory representations (which were fairly noisy); (2) in the temporal domain, selective attention improves the sensory precision in both modalities (both of which were fairly reliable to begin with); (3) in both tasks, selective attention did not exert a significant influence over the tendency to integrate sensory stimuli. Therefore, it may be postulated that a sensory modality must possess a certain inherent degree of encoding precision in order to benefit from selective attention. It also appears that in certain basic perceptual tasks, the tendency to integrate crossmodal signals does not depend significantly on selective attention. We conclude with a discussion of how these results relate to recent theoretical considerations of selective attention. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Department of Defense Tri-Service Precision Machine-Tool Program. Quarterly report, February--April 1978

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1978-06-01

Following a planning period during which the Lawrence Livermore Laboratory and the Department of Defense managing sponsor, the USAF Materials Laboratory, agreed on work statements, the Department of Defense Tri-Service Precision Machine-Tool Program began in February 1978. Milestones scheduled for the first quarter have been met. Tasks and manpower requirements for two basic projects, precision-machining commercialization (PMC) and a machine-tool task force (MTTF), were defined. Progress by PMC includes: (1) documentation of existing precision machine-tool technology by initiation and compilation of a bibliography containing several hundred entries: (2) identification of the problems and needs of precision turning-machine builders and ofmore » precision turning-machine users interested in developing high-precision machining capability; and (3) organization of the schedule and content of the first seminar, to be held in October 1978, which will bring together representatives from the machine-tool and optics communities to address the problems and begin the process of high-precision machining commercialization. Progress by MTTF includes: (1) planning for the organization of a team effort of approximately 60 to 80 international experts to contribute in various ways to project objectives, namely, to summarize state-of-the-art cutting-machine-tool technology and to identify areas where future R and D should prove technically and economically profitable; (2) preparation of a comprehensive plan to achieve those objectives; and (3) preliminary arrangements for a plenary session, also in October, when the task force will meet to formalize the details for implementing the plan.« less

Comparison of precision and speed in laparoscopic and robot-assisted surgical task performance.

PubMed

Zihni, Ahmed; Gerull, William D; Cavallo, Jaime A; Ge, Tianjia; Ray, Shuddhadeb; Chiu, Jason; Brunt, L Michael; Awad, Michael M

2018-03-01

Robotic platforms have the potential advantage of providing additional dexterity and precision to surgeons while performing complex laparoscopic tasks, especially for those in training. Few quantitative evaluations of surgical task performance comparing laparoscopic and robotic platforms among surgeons of varying experience levels have been done. We compared measures of quality and efficiency of Fundamentals of Laparoscopic Surgery task performance on these platforms in novices and experienced laparoscopic and robotic surgeons. Fourteen novices, 12 expert laparoscopic surgeons (>100 laparoscopic procedures performed, no robotics experience), and five expert robotic surgeons (>25 robotic procedures performed) performed three Fundamentals of Laparoscopic Surgery tasks on both laparoscopic and robotic platforms: peg transfer (PT), pattern cutting (PC), and intracorporeal suturing. All tasks were repeated three times by each subject on each platform in a randomized order. Mean completion times and mean errors per trial (EPT) were calculated for each task on both platforms. Results were compared using Student's t-test (P < 0.05 considered statistically significant). Among novices, greater errors were noted during laparoscopic PC (Lap 2.21 versus Robot 0.88 EPT, P < 0.001). Among expert laparoscopists, greater errors were noted during laparoscopic PT compared with robotic (PT: Lap 0.14 versus Robot 0.00 EPT, P = 0.04). Among expert robotic surgeons, greater errors were noted during laparoscopic PC compared with robotic (Lap 0.80 versus Robot 0.13 EPT, P = 0.02). Among expert laparoscopists, task performance was slower on the robotic platform compared with laparoscopy. In comparisons of expert laparoscopists performing tasks on the laparoscopic platform and expert robotic surgeons performing tasks on the robotic platform, expert robotic surgeons demonstrated fewer errors during the PC task (P = 0.009). Robotic assistance provided a reduction in errors at all experience levels for some laparoscopic tasks, but no benefit in the speed of task performance. Robotic assistance may provide some benefit in precision of surgical task performance. Copyright © 2017 Elsevier Inc. All rights reserved.

Obesity-specific neural cost of maintaining gait performance under complex conditions in community-dwelling older adults.

PubMed

Osofundiya, Olufunmilola; Benden, Mark E; Dowdy, Diane; Mehta, Ranjana K

2016-06-01

Recent evidence of obesity-related changes in the prefrontal cortex during cognitive and seated motor activities has surfaced; however, the impact of obesity on neural activity during ambulation remains unclear. The purpose of this study was to determine obesity-specific neural cost of simple and complex ambulation in older adults. Twenty non-obese and obese individuals, 65years and older, performed three tasks varying in the types of complexity of ambulation (simple walking, walking+cognitive dual-task, and precision walking). Maximum oxygenated hemoglobin, a measure of neural activity, was measured bilaterally using a portable functional near infrared spectroscopy system, and gait speed and performance on the complex tasks were also obtained. Complex ambulatory tasks were associated with ~2-3.5 times greater cerebral oxygenation levels and ~30-40% slower gait speeds when compared to the simple walking task. Additionally, obesity was associated with three times greater oxygenation levels, particularly during the precision gait task, despite obese adults demonstrating similar gait speeds and performances on the complex gait tasks as non-obese adults. Compared to existing studies that focus solely on biomechanical outcomes, the present study is one of the first to examine obesity-related differences in neural activity during ambulation in older adults. In order to maintain gait performance, obesity was associated with higher neural costs, and this was augmented during ambulatory tasks requiring greater precision control. These preliminary findings have clinical implications in identifying individuals who are at greater risk of mobility limitations, particularly when performing complex ambulatory tasks. Copyright © 2016 Elsevier Ltd. All rights reserved.

Obligatory encoding of task-irrelevant features depletes working memory resources.

PubMed

Marshall, Louise; Bays, Paul M

2013-02-18

Selective attention is often considered the "gateway" to visual working memory (VWM). However, the extent to which we can voluntarily control which of an object's features enter memory remains subject to debate. Recent research has converged on the concept of VWM as a limited commodity distributed between elements of a visual scene. Consequently, as memory load increases, the fidelity with which each visual feature is stored decreases. Here we used changes in recall precision to probe whether task-irrelevant features were encoded into VWM when individuals were asked to store specific feature dimensions. Recall precision for both color and orientation was significantly enhanced when task-irrelevant features were removed, but knowledge of which features would be probed provided no advantage over having to memorize both features of all items. Next, we assessed the effect an interpolated orientation-or color-matching task had on the resolution with which orientations in a memory array were stored. We found that the presence of orientation information in the second array disrupted memory of the first array. The cost to recall precision was identical whether the interfering features had to be remembered, attended to, or could be ignored. Therefore, it appears that storing, or merely attending to, one feature of an object is sufficient to promote automatic encoding of all its features, depleting VWM resources. However, the precision cost was abolished when the match task preceded the memory array. So, while encoding is automatic, maintenance is voluntary, allowing resources to be reallocated to store new visual information.

Further Results on the Disturbance Response of a Double Integrator Controlled by Saturating Linear Static State Feedback

DTIC Science & Technology

2011-07-13

Anton A. Stoorvogel b, Håvard Fjær Grip a aSchool of Electrical Engineering and Computer Science, Washington State University, Pullman, WA 99164-2752...utwente.nl ( Anton A. Stoorvogel), grip@ieee.org (Håvard Fjær Grip). of a double integrator controlled by a saturating linear static state feedback...References Chitour, Y., 2001. On the Lp stabilization of the double integrator subject to input saturation. ESAIM: Control, Optimization and Calculus

GRIP Experiment 2010

NASA Image and Video Library

2010-08-14

Jeffrey Beyon, left, and Paul Joseph Petzar, right, from NASA's Langley Research Center, work with DAWN Air Data Acquisition and Processing software aboard NASA's DC-8 research aircraft, Sunday, Aug. 15, 2010, in support of the GRIP experiment at Fort Lauderdale International Airport in Fort Lauderdale, Fla. The Genesis and Rapid Intensification Processes (GRIP) experiment is a NASA Earth science field experiment in 2010 that is being conducted to better understand how tropical storms form and develop into major hurricanes. Photo Credit: (NASA/Paul E. Alers)

Cooperative mission execution and planning

NASA Astrophysics Data System (ADS)

Flann, Nicholas S.; Saunders, Kevin S.; Pells, Larry

1998-08-01

Utilizing multiple cooperating autonomous vehicles to perform tasks enhances robustness and efficiency over the use of a single vehicle. Furthermore, because autonomous vehicles can be controlled precisely and their status known accurately in real time, new types of cooperative behaviors are possible. This paper presents a working system called MEPS that plans and executes missions for multiple autonomous vehicles in large structured environments. Two generic spatial tasks are supported, to sweep an area and to visit a location while activating on-board equipment. Tasks can be entered both initially by the user and dynamically during mission execution by both users and vehicles. Sensor data and task achievement data is shared among the vehicles enabling them to cooperatively adapt to changing environmental, vehicle and tasks conditions. The system has been successfully applied to control ATV and micro-robotic vehicles in precision agriculture and waste-site characterization environments.

A bio-inspired approach for the design of a multifunctional robotic end-effector customized for automated maintenance of a reconfigurable vibrating screen.

PubMed

Makinde, O A; Mpofu, K; Vrabic, R; Ramatsetse, B I

2017-01-01

The development of a robotic-driven maintenance solution capable of automatically maintaining reconfigurable vibrating screen (RVS) machine when utilized in dangerous and hazardous underground mining environment has called for the design of a multifunctional robotic end-effector capable of carrying out all the maintenance tasks on the RVS machine. In view of this, the paper presents a bio-inspired approach which unfolds the design of a novel multifunctional robotic end-effector embedded with mechanical and control mechanisms capable of automatically maintaining the RVS machine. To achieve this, therblig and morphological methodologies (which classifies the motions as well as the actions required by the robotic end-effector in carrying out RVS machine maintenance tasks), obtained from a detailed analogy of how human being (i.e. a machine maintenance manager) will carry out different maintenance tasks on the RVS machine, were used to obtain the maintenance objective functions or goals of the multifunctional robotic end-effector as well as the maintenance activity constraints of the RVS machine that must be adhered to by the multifunctional robotic end-effector during the machine maintenance. The results of the therblig and morphological analyses of five (5) different maintenance tasks capture and classify one hundred and thirty-four (134) repetitive motions and fifty-four (54) functions required in automating the maintenance tasks of the RVS machine. Based on these findings, a worm-gear mechanism embedded with fingers extruded with a hexagonal shaped heads capable of carrying out the "gripping and ungrasping" and "loosening and bolting" functions of the robotic end-effector and an electric cylinder actuator module capable of carrying out "unpinning and hammering" functions of the robotic end-effector were integrated together to produce the customized multifunctional robotic end-effector capable of automatically maintaining the RVS machine. The axial forces ([Formula: see text] and [Formula: see text]), normal forces ([Formula: see text]) and total load [Formula: see text] acting on the teeth of the worm-gear module of the multifunctional robotic end-effector during the gripping of worn-out or new RVS machine subsystems, which are 978.547, 1245.06 and 1016.406 N, respectively, were satisfactory. The nominal bending and torsional stresses acting on the shoulder of the socket module of the multifunctional robotic end-effector during the loosing and tightening of bolts, which are 1450.72 and 179.523 MPa, respectively, were satisfactory. The hammering and unpinning forces utilized by the electric cylinder actuator module of the multifunctional robotic end-effector during the unpinning and hammering of screen panel pins out of and into the screen panels were satisfactory.

Right- and left-brain hemisphere. Rhythm in reaction time to light signals is task-load-dependent: age, gender, and handgrip strength rhythm comparisons.

PubMed

Reinberg, Alain; Bicakova-Rocher, Alena; Mechkouri, Mohamed; Ashkenazi, Israel

2002-11-01

In healthy mature subjects simple reaction time (SRT) to a single light signal (an easy task) is associated with a prominent rhythm with tau = 24 h of dominant (DH) as well as nondominant (NDH) hand performance, while three-choice reaction time (CRT), a complex task, is associated with tau = 24 h of the DH but tau < 24 h of the NDH. The aims of the study were to assess the influence of age and gender on the difference in tau of the NDH and DH, as it relates to the corresponding cortical hemisphere of the brain, in comparison to the rhythm in handgrip strength. Healthy subjects, 9 (5 M and 4 F) adolescents 10-16 yr of age and 15 (8 M and 7 F) adults 18-67 yr of age, active between 08:00 +/- 1 h and 23:00 +/- 1:30 h and free of alcohol, tobacco, and drug consumption volunteered. Data were gathered longitudinally at home and work 4-7 times daily for 11-20 d. At each test time the following variables were assessed: grip strength of both hands (Dynamometer: Colin-Gentile, Paris, France); single reaction time to a yellow signal (SRT); and CRT to randomized yellow, red, or green signal series with varying instruction from test to test (Psycholog-24: Biophyderm, France). Rhythms in the performance in SRT, CRT, and handgrip strength of both DH and NDH were explored. The sleep-wake rhythm was assessed by sleep-logs, and in a subset of 14 subjects it was also assessed by wrist actigraphy (Mini-Motionlogger: AMI, Ardsley NY). Exploration of the prominent period tau of time series was achieved by a special power spectra analysis for unequally spaced data. Cosinor analysis was used to quantify the rhythm amplitude A and rhythm-adjusted mean M of the power spectral analysis determined trial tau. A 24h sleep-wake rhythm was detected in almost all cases. In adults, a prominent tau of 24 h characterized the performance of the easy task by both the DH and NDH. In adults a prominent tau of 24 h was also detected in the complex CRT task performed by the DH, but for the NDH the tau was < 24 h. This phenomenon was not gender-related but was age-related since it was seldom observed in adolescent subjects. Hand-side differences in the grip strength rhythms in the same individuals were detected, the tau being ultradian rather than circadian in adolescent subjects while in mature subjects the tau frequently differed from that of the rhythm in CRT. These findings further support the hypothesis that functional biological clocks exist in both the left and right hemispheres of the human cortex.

Revolutionizing (robot-assisted) laparoscopic gamma tracing using a drop-in gamma probe technology

PubMed Central

van Oosterom, Matthias N; Simon, Hervé; Mengus, Laurent; Welling, Mick M; van der Poel, Henk G; van den Berg, Nynke S; van Leeuwen, Fijs WB

2016-01-01

In complex (robot-assisted) laparoscopic radioguided surgery procedures, or when low activity lesions are located nearby a high activity background, the limited maneuverability of a laparoscopic gamma probe (LGP; 4 degrees of freedom (DOF)) may hinder lesion identification. We investigated a drop-in gamma probe (DIGP) technology to be inserted via a trocar, after which the laparoscopic surgical tool at hand can pick it up and maneuver it. Phantom experiments showed that distinguishing a low objective from a high background source (1:100 ratio) was only possible with the detector faced >90° from the high background source. Signal-low-objective-to-background ratios of 3.77, 2.01 and 1.84 were found for detector angles of 90°, 135° and 180°, respectively, whereas detector angles of 0° and 45° were unable to distinguish the sources. This underlines the critical role probe positioning plays. We then focused on engineering of the gripping part for optimal DIGP pick-up with a conventional laparoscopic forceps (4 DOF) or a robotic forceps (6 DOF). DIGPs with 0°, 45°, 90°, and 135° -grip orientations were designed, and their maneuverability- and scanning direction were evaluated and compared to a conventional LGP. The maneuverability- and scanning direction of the DIGP was found highest when using the robotic forceps, with the largest effective scanning direction range obtained with the 90° -grip design (0-180° versus 0-111°, 0-140°, and 37-180° for 0°, 45° and 135° -grip designs, respectively). For the laparoscopic forceps, the scan direction directly translated from the angle of the grip design with the advantage that the 135° -gripped DIGP could be faced backwards (not possible with the conventional LGP). In the ex vivo clinical setup, the surgeon rated DIGP pick-up most convenient for the 45°-grip design. Concluding, the DIGP technology was successfully introduced. Optimization of the grip design and grasping angle of the DIGP increased its utility for (robot-assisted) laparoscopic gamma tracing. PMID:27069762

Memory-guided force output is associated with self-reported ADHD symptoms in young adults.

PubMed

Neely, Kristina A; Chennavasin, Amanda P; Yoder, Arie; Williams, Genevieve K R; Loken, Eric; Huang-Pollock, Cynthia L

2016-11-01

Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed mental health disorder in childhood and persists into adulthood in up to 65 % of cases. ADHD is associated with adverse outcomes such as the ability to gain and maintain employment and is associated with an increased risk for substance abuse obesity workplace injuries and traffic accidents A majority of diagnosed children have motor deficits; however, few studies have examined motor deficits in young adults. This study provides a novel examination of visuomotor control of grip force in young adults with and without ADHD. Participants were instructed to maintain force production over a 20-second trial with and without real-time visual feedback about their performance. The results demonstrated that when visual feedback was available, adults with ADHD produced slightly higher grip force than controls. However, when visual feedback was removed, adults with ADHD had a faster rate of decay of force, which was associated with ADHD symptom severity and trait impulsivity. These findings suggest that there may be important differences in the way that adults with ADHD integrate visual feedback during continuous motor tasks. These may account for some of the motor impairments reported in children with ADHD. These deficits could result from (1) dysfunctional sensory motor integration and/or (2) deficits in short-term visuomotor memory.

Integrated dynamic and static tactile sensor: focus on static force sensing

NASA Astrophysics Data System (ADS)

Wettels, Nicholas; Pletner, Baruch

2012-04-01

Object grasping by robotic hands in unstructured environments demands a sensor that is durable, compliant, and responsive to static and dynamic force conditions. In order for a tactile sensor to be useful for grasp control in these, it should have the following properties: tri-axial force sensing (two shear plus normal component), dynamic event sensing across slip frequencies, compliant surface for grip, wide dynamic range (depending on application), insensitivity to environmental conditions, ability to withstand abuse and good sensing behavior (e.g. low hysteresis, high repeatability). These features can be combined in a novel multimodal tactile sensor. This sensor combines commercial-off-the-shelf MEMS technology with two proprietary force sensors: a high bandwidth device based on PZT technology and low bandwidth device based on elastomers and optics. In this study, we focus on the latter transduction mechanism and the proposed architecture of the completed device. In this study, an embedded LED was utilized to produce a constant light source throughout a layer of silicon rubber which covered a plastic mandrel containing a set of sensitive phototransistors. Features about the contacted object such as center of pressure and force vectors can be extracted from the information in the changing patterns of light. The voltage versus force relationship obtained with this molded humanlike finger had a wide dynamic range that coincided with forces relevant for most human grip tasks.

Relationship between output from MIDI-keyboard playing and hand function assessments on affected hand after stroke.

PubMed

Chong, Hyun Ju; Han, Soo Jeong; Kim, Yong Jae; Park, Hye Young; Kim, Soo Ji

2014-01-01

While a number of studies have tested the therapeutic effectiveness of playing musical instruments, such as the electronic keyboard using Musical Instrument Digital Interface (MIDI), it is still unclear whether outcomes of electronic keyboard playing are related to hand function tests. The purpose of this study was to investigate the correlation between MIDI-keyboard playing and hand function tests, including grip strength, Box and Block test (BBT), and Jensen-Taylor Hand Function Test (JTHF). A total of 66 stroke patients were recruited from medical centers and were classified into acute (n = 21), subacute (n = 28), and chronic (n = 17) recovery stages. The participants' mean age was 60.5 years. The MIDI-keyboard playing protocol based on sequential key pressing was implemented. All hand function tests were performed by certified occupational therapists. MIDI scores from participants at all three recovery stages were significantly correlated with BBT and grip strength. Overall, MIDI-keyboard playing scores demonstrated moderate to high correlations with hand function tests except for participants at the chronic stage and the JTHF, which showed no correlation. These findings suggest that MIDI-keyboard playing has great potential as an assessment tool of hand function, especially hand dexterity in acute and subacute stroke patients. Further studies are needed to refine the specific keyboard playing tasks that increase responsiveness to traditional hand function tests.

Effects of pressure, cold and gloves on hand skin temperature and manual performance of divers.

PubMed

Zander, Joanna; Morrison, James

2008-09-01

Cold water immersion and protective gloves are associated with decreased manual performance. Although neoprene gloves slow hand cooling, there is little information on whether they provide sufficient protection when diving in cold water. Nine divers wearing three-fingered neoprene gloves and dry suits were immersed in water at 25 and 4 degrees C, at depths of 0.4 msw (101 kPa altitude adjusted) and 40 msw (497 kPa) in a hyperbaric chamber. Skin temperatures were measured at the fingers, hand, forearm, chest and head. Grip strength, tactile sensitivity and manual dexterity were measured at three time intervals. There was an exponential decay in finger and back of hand skin temperatures with exposure time in 4 degrees C water. Finger and back of hand skin temperatures were lower at 40 msw than at 0.4 msw (P < 0.05). There was no effect of pressure or temperature on grip strength. Tactile sensitivity decreased linearly with finger skin temperature at both pressures. Manual dexterity was not affected by finger skin temperature at 0.4 msw, but decreased with fall in finger skin temperature at 40 msw. Results show that neoprene gloves do not provide adequate thermal protection in 4 degrees C water and that impairment of manual performance is dependent on the type of task, depth and exposure time.

Grip strength measurement for frailty assessment in patients with vascular disease and associations with comorbidity, cardiac risk, and sarcopenia.

PubMed

Reeve, Thomas E; Ur, Rebecca; Craven, Timothy E; Kaan, James H; Goldman, Matthew P; Edwards, Matthew S; Hurie, Justin B; Velazquez-Ramirez, Gabriela; Corriere, Matthew A

2018-05-01

Frailty is associated with adverse events, length of stay, and nonhome discharge after vascular surgery. Frailty measures based on walking-based tests may be impractical or invalid for patients with walking impairment from symptoms or sequelae of vascular disease. We hypothesized that grip strength is associated with frailty, comorbidity, and cardiac risk among patients with vascular disease. Dominant hand grip strength was measured during ambulatory clinic visits among patients with vascular disease (abdominal aortic aneurysm [AAA], carotid stenosis, and peripheral artery disease [PAD]). Frailty prevalence was defined on the basis of the 20th percentile of community-dwelling population estimates adjusted for age, gender, and body mass index. Associations between grip strength, Charlson Comorbidity Index (CCI), Revised Cardiac Risk Index (RCRI), and sarcopenia (based on total psoas area for patients with cross-sectional abdominal imaging) were evaluated using linear and logistic regression. Grip strength was measured in 311 participants; all had sufficient data for CCI calculation, 217 (69.8%) had sufficient data for RCRI, and 88 (28.3%) had cross-sectional imaging permitting psoas measurement. Eighty-six participants (27.7%) were categorized as frail on the basis of grip strength. Frailty was associated with CCI (odds ratio, 1.86; 95% confidence interval, 1.34-2.57; P = .0002) in the multivariable model. Frail participants also had a higher average number of RCRI components vs nonfrail patients (mean ± standard deviation, 1.8 ± 0.8 for frail vs 1.5 ± 0.7 for nonfrail; P = .018); frailty was also associated with RCRI in the adjusted multivariable model (odds ratio, 1.75; 95% confidence interval, 1.16-2.64; P = .008). Total psoas area was lower among patients categorized as frail vs nonfrail on the basis of grip strength (21.0 ± 6.6 vs 25.4 ± 7.4; P = .010). Each 10 cm 2 increase in psoas area was associated with a 5.7 kg increase in grip strength in a multivariable model adjusting for age and gender (P < .0001). Adjusted least squares mean psoas diameter estimates were 25.5 ± 1.1 cm 2 for participants with AAA, 26.7 ± 2.0 cm 2 for participants with carotid stenosis, and 22.7 ± 0.8 cm 2 for participants with PAD (P = .053 for PAD vs AAA; P = .057 for PAD vs carotid stenosis; and P = .564 for AAA vs carotid stenosis). Grip strength is useful for identifying frailty among patients with vascular disease. Frail status based on grip strength is associated with comorbidity, cardiac risk, and sarcopenia in this population. These findings suggest that grip strength may have utility as a simple and inexpensive risk screening tool that is easily implemented in ambulatory clinics, avoids the need for imaging, and overcomes possible limitations of walking-based measures. Lower mean psoas diameters among patients with PAD vs other diagnoses may warrant consideration of specific approaches to morphomic analysis. Copyright © 2017 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Automatically rating trainee skill at a pediatric laparoscopic suturing task.

PubMed

Oquendo, Yousi A; Riddle, Elijah W; Hiller, Dennis; Blinman, Thane A; Kuchenbecker, Katherine J

2018-04-01

Minimally invasive surgeons must acquire complex technical skills while minimizing patient risk, a challenge that is magnified in pediatric surgery. Trainees need realistic practice with frequent detailed feedback, but human grading is tedious and subjective. We aim to validate a novel motion-tracking system and algorithms that automatically evaluate trainee performance of a pediatric laparoscopic suturing task. Subjects (n = 32) ranging from medical students to fellows performed two trials of intracorporeal suturing in a custom pediatric laparoscopic box trainer after watching a video of ideal performance. The motions of the tools and endoscope were recorded over time using a magnetic sensing system, and both tool grip angles were recorded using handle-mounted flex sensors. An expert rated the 63 trial videos on five domains from the Objective Structured Assessment of Technical Skill (OSATS), yielding summed scores from 5 to 20. Motion data from each trial were processed to calculate 280 features. We used regularized least squares regression to identify the most predictive features from different subsets of the motion data and then built six regression tree models that predict summed OSATS score. Model accuracy was evaluated via leave-one-subject-out cross-validation. The model that used all sensor data streams performed best, achieving 71% accuracy at predicting summed scores within 2 points, 89% accuracy within 4, and a correlation of 0.85 with human ratings. 59% of the rounded average OSATS score predictions were perfect, and 100% were within 1 point. This model employed 87 features, including none based on completion time, 77 from tool tip motion, 3 from tool tip visibility, and 7 from grip angle. Our novel hardware and software automatically rated previously unseen trials with summed OSATS scores that closely match human expert ratings. Such a system facilitates more feedback-intensive surgical training and may yield insights into the fundamental components of surgical skill.

Multi-finger prehension: control of a redundant mechanical system.

PubMed

Latash, Mark L; Zatsiorsky, Vladimir M

2009-01-01

The human hand has been a fascinating object of study for researchers in both biomechanics and motor control. Studies of human prehension have contributed significantly to the progress in addressing the famous problem of motor redundancy. After a brief review of the hand mechanics, we present results of recent studies that support a general view that the apparently redundant design of the hand is not a source of computational problems but a rich apparatus that allows performing a variety of tasks in a reliable and flexible way (the principle of abundance). Multi-digit synergies have been analyzed at two levels of a hypothetical hierarchy involved in the control of prehensile actions. At the upper level, forces and moments produced by the thumb and virtual finger (an imagined finger with a mechanical action equal to the combined mechanical action of all four fingers of the hand) co-vary to stabilize the gripping action and the orientation of the hand-held object. These results support the principle of superposition suggested earlier in robotics with respect to the control of artificial grippers. At the lower level of the hierarchy, forces and moments produced by individual fingers co-vary to stabilize the magnitude and direction of the force vector and the moment of force produced by the virtual finger. Adjustments to changes in task constraints (such as, for example, friction under individual digits) may be local and synergic. The latter reflect multi-digit prehension synergies and may be analyzed with the so-called chain effects: Sequences of relatively straightforward cause-effect links directly related to mechanical constraints leading to non-trivial strong co-variation between pairs of elemental variables. Analysis of grip force adjustments during motion of hand-held objects suggests that the central nervous system adjusts to gravitational and inertial loads differently. The human hand is a gold mine for researchers interested in the control of natural human movements.

Grasp posture alters visual processing biases near the hands

PubMed Central

Thomas, Laura E.

2015-01-01

Observers experience biases in visual processing for objects within easy reach of their hands that may assist them in evaluating items that are candidates for action. I investigated the hypothesis that hand postures affording different types of actions differentially bias vision. Across three experiments, participants performed global motion detection and global form perception tasks while their hands were positioned a) near the display in a posture affording a power grasp, b) near the display in a posture affording a precision grasp, or c) in their laps. Although the power grasp posture facilitated performance on the motion task, the precision grasp posture instead facilitated performance on the form task. These results suggest that the visual system weights processing based on an observer’s current affordances for specific actions: fast and forceful power grasps enhance temporal sensitivity, while detail-oriented precision grasps enhance spatial sensitivity. PMID:25862545

Effect of task-oriented activities on hand functions, cognitive functions and self-expression of elderly patients with dementia.

PubMed

Son, Bo-Young; Bang, Yo-Soon; Hwang, Min-Ji; Oh, Eun-Ju

2017-08-01

[Purpose] This study investigates the effects of task-oriented activities on hand function, cognitive function, and self-expression of the elderly with dementia, and then identify the influencing factors on self-expression in sub-factors of dependent variables. [Subjects and Methods] Forty elderly persons were divided into two groups: intervention group (n=20) and control group (n=20). The interventions were applied to the subjects 3 times a week, 50 minutes per each time, for a total of five weeks. We measured the jamar hand dynamometer test for grip strength, the jamar hydraulic pinch gauge test for prehension test, nine-hole pegboard test for coordination test, and Loewenstein Occupational Therapy Cognitive Assessment-Geriatric Population for cognitive function, and self-expression rating scale for self-expression test. [Results] The task-oriented activities promoted hand function, cognitive function (visual perception, spatial perception, visuomotor organization, attention & concentration) and self-expression of the elderly with early dementia, and the factors influencing the self-expression were cognitive function (visual perception) and hand function (coordination). The study showed that the task-oriented program enabled self-expression by improving hand function and cognitive function. [Conclusion] This study suggested that there should be provided the task-oriented program for prevention and treatment of the elderly with early dementia in the clinical settings and it was considered that results have a value as basic data that can be verified relationship of hand function, cognitive function, and self-expression.

Pilot study on verification of effectiveness on operability of assistance system for robotic tele-surgery using simulation.

PubMed

Kawamura, Kazuya; Kobayashi, Yo; Fujie, Masakatsu G

2010-01-01

Tele-surgery enables medical care even in remote regions, and has been accomplished in clinical cases by means of dedicated communication lines. To make tele-surgery a more widespread method of providing medical care, a surgical environment needs to be made available using public lines of communication, such as the Internet. Moreover, a support system during surgery is required, as the use of surgical tools is performed in an environment subject to delay. In our research, we focus on the operability of specific tasks conducted by surgeons during a medical procedure, with the aim of clarifying, by means of a simulation, the optimum environment for robotic tele-surgery. In the study, we set up experimental systems using our proposed simulation system. In addition, we investigate the mental workloads on subjects and verify the effect of visual-assistance information as a pilot study. The operability of the task of gripping soft tissue was evaluated using a subjective workload assessment tool, the NASA Task Load Index. Results show that the tasks were completed, but the workload did not improve to less than 300ms and 400ms in the simulated environment. Verifying the effect of the support system was an important task under a more-than 200ms delay using this experiment, and future studies will evaluate the operability of the system under varying conditions of comfort. In addition, an intra-operative assistance system will be constructed using a simulation.

Effect of task-oriented activities on hand functions, cognitive functions and self-expression of elderly patients with dementia

PubMed Central

Son, Bo-Young; Bang, Yo-Soon; Hwang, Min-Ji; Oh, Eun-Ju

2017-01-01

[Purpose] This study investigates the effects of task-oriented activities on hand function, cognitive function, and self-expression of the elderly with dementia, and then identify the influencing factors on self-expression in sub-factors of dependent variables. [Subjects and Methods] Forty elderly persons were divided into two groups: intervention group (n=20) and control group (n=20). The interventions were applied to the subjects 3 times a week, 50 minutes per each time, for a total of five weeks. We measured the jamar hand dynamometer test for grip strength, the jamar hydraulic pinch gauge test for prehension test, nine-hole pegboard test for coordination test, and Loewenstein Occupational Therapy Cognitive Assessment-Geriatric Population for cognitive function, and self-expression rating scale for self-expression test. [Results] The task-oriented activities promoted hand function, cognitive function (visual perception, spatial perception, visuomotor organization, attention & concentration) and self-expression of the elderly with early dementia, and the factors influencing the self-expression were cognitive function (visual perception) and hand function (coordination). The study showed that the task-oriented program enabled self-expression by improving hand function and cognitive function. [Conclusion] This study suggested that there should be provided the task-oriented program for prevention and treatment of the elderly with early dementia in the clinical settings and it was considered that results have a value as basic data that can be verified relationship of hand function, cognitive function, and self-expression. PMID:28878462

Neural correlates of motor recovery after stroke: a longitudinal fMRI study

PubMed Central

Ward, N. S.; Brown, M. M.; Thompson, A. J.; Frackowiak, R. S. J.

2013-01-01

Summary Recovery of motor function after stroke may occur over weeks or months and is often attributed to cerebral reorganization. We have investigated the longitudinal relationship between recovery after stroke and task-related brain activation during a motor task as measured using functional MRI (fMRI). Eight first-ever stroke patients presenting with hemiparesis resulting from cerebral infarction sparing the primary motor cortex, and four control subjects were recruited. Subjects were scanned on a number of occasions whilst performing an isometric dynamic visually paced hand grip task. Recovery in the patient group was assessed using a battery of outcome measures at each time point. Task-related brain activations decreased over sessions as a function of recovery in a number of primary and non-primary motor regions in all patients, but no session effects were seen in the controls. Furthermore, consistent decreases across sessions correlating with recovery were seen across the whole patient group independent of rate of recovery or initial severity, in primary motor cortex, premotor and prefrontal cortex, supplementary motor areas, cingulate sulcus, temporal lobe, striate cortex, cerebellum, thalamus and basal ganglia. Although recovery-related increases were seen in different brain regions in four patients, there were no consistent effects across the group. These results further our understanding of the recovery process by demonstrating for the first time a clear temporal relationship between recovery and task-related activation of the motor system after stroke. PMID:12937084

Associations between aging-related changes in grip strength and cognitive function in older adults: A systematic review.

PubMed

Zammit, Andrea R; Robitaille, Annie; Piccinin, Andrea; Muniz-Terrera, Graciela; Hofer, Scott M

2018-03-08

Grip strength and cognitive function reflect upper body muscle strength and mental capacities. Cross-sectional research has suggested that in old age these two processes are moderately to highly associated, and that an underlying common cause drives this association. Our aim was to synthesize and evaluate longitudinal research addressing whether changes in grip strength are associated with changes in cognitive function in healthy older adults. We systematically reviewed English-language research investigating the longitudinal association between repeated measures of grip strength and of cognitive function in community-dwelling older adults to evaluate the extent to which the two indices decline concurrently. We used four search engines: Embase, PsychINFO, PubMed, and Web of Science. Of 459 unique citations, 6 met our full criteria: 4 studies reported a longitudinal association between rates of change in grip strength and cognitive function in older adults, 2 of which reported the magnitudes of these associations as ranging from low to moderate; 2 studies reported significant cross-sectional but not longitudinal associations among rates of change. All studies concluded that cognitive function and grip strength declined, on average, with increasing age, although with little to no evidence for longitudinal associations among rates of change. Future research is urged to expand the study of physical and cognitive associations in old age using a within-person and multi-study integrative approach to evaluate the reliability of longitudinal results with greater emphasis on the magnitude of this association.

Physical Activity and Kidney Injury in Pediatric and Young Adult Kidney Transplant Recipients.

PubMed

Wolf, Mattie F; George, Roshan P; Warshaw, Barry; Wang, Elizabeth; Greenbaum, Larry A

2016-12-01

To quantify physical activity and grip strength in pediatric kidney transplant recipients and describe attitudes about exercise and exercise counseling given concerns about allograft injury. This was a cross-sectional analysis of 101 kidney transplant recipients (7-21 years old) >6 months post-transplant. Patients completed the Physical Activity Questionnaire (PAQ). Grip strength was measured with a dynamometer. We asked about activity limitations and provider counseling. Univariate analysis and multiple linear regression were used to determine independent predictors of PAQ score and grip strength z score. We enrolled 101 of 122 eligible patients. Median PAQ score was 2.2 (range 0-5) and was lower compared with controls (P < .001). The average grip strength z score was -1.1 and -0.7 in the right and left hand, respectively. Predictors of lower grip strength were younger age (P = .036), non-African American race (P = .029), lower height z score (P = .010), and longer percentage of lifetime with kidney disease (P = .029). Although 49% and 67% limited exercise before and after transplant, respectively, 67% reported increased activity after transplant. By parent report, provider counseling included limiting certain activities (71%) and encouraging regular exercise (45%). Physical activity and grip strength are low after kidney transplant. Patients perceive an emphasis on exercise limitations rather than the benefits of regular exercise. Interventions that encourage physical activity may be beneficial. Copyright © 2016 Elsevier Inc. All rights reserved.

Associations of work activities requiring pinch or hand grip or exposure to hand-arm vibration with finger and wrist osteoarthritis: a meta-analysis.

PubMed

Hammer, Paula E C; Shiri, Rahman; Kryger, Ann I; Kirkeskov, Lilli; Bonde, Jens Peter

2014-03-01

We systematically reviewed the epidemiologic evidence linking finger and wrist osteoarthritis (OA) with work activities requiring pinch or hand grip or exposure to hand-arm vibration (HAV). PubMed and Embase databases were searched up to June 2013. We selected studies assessing the associations of radiographic diagnosed finger and/or wrist joint OA with work activities involving pinch or hand grip or exposure to HAV. We used specific criteria to evaluate completeness of reporting, potential confounding, and bias. Pooled odds ratios (OR) were computed using random-effects meta-analyses. Of the 19 studies included, 17 were cross-sectional, 1 was a prospective cohort, and 1 a case-control study. The meta-analyses of studies that controlled their estimates for at least age and gender showed the associations of pinch grip work with proximal interphalangeal joint [OR 1.56, 95% confidence interval (95% CI) 1.09-2.23] and the first carpometacarpal joint OA (OR 2.10, 95% CI 1.06-4.17), but not with distal interphalangeal, metacarpalphalangeal, or wrist joints OA. Hand grip work and exposure to HAV were not associated with any finger or wrist OA. Epidemiological studies provide limited evidence that pinch grip may increase the risk of wrist or finger OA, but causal relation cannot be resolved because of cross-sectional designs and inadequate characterization of biomechanical strain to the hand and wrist.

Anhedonia in schizophrenia: Deficits in both motivation and hedonic capacity.

PubMed

Wang, Jiao; Huang, Jia; Yang, Xin-Hua; Lui, Simon S Y; Cheung, Eric F C; Chan, Raymond C K

2015-10-01

Anhedonia is one of the core negative symptoms of schizophrenia that affect the ultimate outcome of this disorder. It is unclear whether the motivational or the hedonic component of anhedonia is impaired in patients with schizophrenia. This study examined the deficits in motivation and hedonic capacity in patients with schizophrenia using an Effort-based pleasure experience task (E-pet). Twenty-two schizophrenia patients with prominent negative symptoms, 18 schizophrenia patients without prominent negative symptoms and 29 healthy controls participated in the present study. All of them were administered the E-pet task, which required the participants to make decisions on whether to choose a hard or easy task based on probability and reward magnitude. When making the grip effort allocation decision, schizophrenia patients with prominent negative symptoms were significantly less likely to choose a hard task than healthy controls. As the reward magnitude and the estimated reward value increased, unlike healthy controls, schizophrenia patients with prominent negative symptoms did not increase their hard task choices. They were also significantly less likely to choose a hard task than healthy controls in medium and high probability conditions. When anticipating potential rewards, these patients reported significantly less anticipatory pleasure than healthy controls, even when reward probability and magnitude increased. The pleasure experience rating after obtaining the actual reward was positively correlated with two pleasure experience scales in schizophrenia patients. In conclusion, patients with schizophrenia, especially those with prominent negative symptoms, showed deficits in both reward motivation and anticipatory pleasure experience. Copyright © 2015 Elsevier B.V. All rights reserved.

The role of judgment frames and task precision in object attention: Reduced template sharpness limits dual-object performance.

PubMed

Liu, Shiau-Hua; Dosher, Barbara Anne; Lu, Zhong-Lin

2009-06-01

Multiple attributes of a single-object are often processed more easily than attributes of different objects-a phenomenon associated with object attention. Here we investigate the influence of two factors, judgment frames and judgment precision, on dual-object report deficits as an index of object attention. [Han, S., Dosher, B., & Lu, Z.-L. (2003). Object attention revisited: Identifying mechanisms and boundary conditions. Psychological Science, 14, 598-604] predicted that consistency of the frame for judgments about two separate objects could reduce or eliminate the expression of object attention limitations. The current studies examine the effects of judgment frames and of task precision in orientation identification and find that dual-object report deficits within one feature are indeed affected modestly by the congruency of the judgments and more substantially by the required precision of judgments. The observed dual-object deficits affected contrast thresholds for incongruent frame conditions and for high precision judgments and reduce psychometric asymptotes. These dual-object deficits reflect a combined effect of multiplicative noise and external noise exclusion in dual-object conditions, both related to the effects of attention on the tuning of perceptual templates. These results have implications for modification of object attention theory, for understanding limitations on concurrent tasks.

Training improves laparoscopic tasks performance and decreases operator workload.

PubMed

Hu, Jesse S L; Lu, Jirong; Tan, Wee Boon; Lomanto, Davide

2016-05-01

It has been postulated that increased operator workload during task performance may increase fatigue and surgical errors. The National Aeronautics and Space Administration-Task Load Index (NASA-TLX) is a validated tool for self-assessment for workload. Our study aims to assess the relationship of workload and performance of novices in simulated laparoscopic tasks of different complexity levels before and after training. Forty-seven novices without prior laparoscopic experience were recruited in a trial to investigate whether training improves task performance as well as mental workload. The participants were tested on three standard tasks (ring transfer, precision cutting and intracorporeal suturing) in increasing complexity based on the Fundamentals of Laparoscopic Surgery (FLS) curriculum. Following a period of training and rest, participants were tested again. Test scores were computed from time taken and time penalties for precision errors. Test scores and NASA-TLX scores were recorded pre- and post-training and analysed using paired t tests. One-way repeated measures ANOVA was used to analyse differences in NASA-TLX scores between the three tasks. NASA-TLX score was lowest with ring transfer and highest with intracorporeal suturing. This was statistically significant in both pre-training (p < 0.001) and post-training (p < 0.001). NASA-TLX scores mirror the changes in test scores for the three tasks. Workload scores decreased significantly after training for all three tasks (ring transfer = 2.93, p < 0.001, precision cutting = 3.74, p < 0.001, intracorporeal suturing = 2.98, p < 0.001). NASA-TLX score is an accurate reflection of the complexity of simulated laparoscopic tasks in the FLS curriculum. This also correlates with the relationship of test scores between the three tasks. Simulation training improves both performance score and workload score across the tasks.

Gain-of-function glutamate receptor interacting protein 1 variants alter GluA2 recycling and surface distribution in patients with autism

PubMed Central

Mejias, Rebeca; Adamczyk, Abby; Anggono, Victor; Niranjan, Tejasvi; Thomas, Gareth M.; Sharma, Kamal; Skinner, Cindy; Schwartz, Charles E.; Stevenson, Roger E.; Fallin, M. Daniele; Kaufmann, Walter; Pletnikov, Mikhail; Valle, David; Huganir, Richard L.; Wang, Tao

2011-01-01

Glutamate receptor interacting protein 1 (GRIP1) is a neuronal scaffolding protein that interacts directly with the C termini of glutamate receptors 2/3 (GluA2/3) via its PDZ domains 4 to 6 (PDZ4–6). We found an association (P < 0.05) of a SNP within the PDZ4-6 genomic region with autism by genotyping autistic patients (n = 480) and matched controls (n = 480). Parallel sequencing identified five rare missense variants within or near PDZ4–6 only in the autism cohort, resulting in a higher cumulative mutation load (P = 0.032). Two variants correlated with a more severe deficit in reciprocal social interaction in affected sibling pairs from proband families. These variants were associated with altered interactions with GluA2/3 and faster recycling and increased surface distribution of GluA2 in neurons, suggesting gain-of-function because GRIP1/2 deficiency showed opposite phenotypes. Grip1/2 knockout mice exhibited increased sociability and impaired prepulse inhibition. These results support a role for GRIP in social behavior and implicate GRIP1 variants in modulating autistic phenotype. PMID:21383172

Development and Applications of a Self-Contained, Non-Invasive EVA Joint Angle and Muscle Fatigue Sensor System

NASA Technical Reports Server (NTRS)

Ranniger, C. U.; Sorenson, E. A.; Akin, D. L.

1995-01-01

The University of Maryland Space Systems Laboratory, as a participant in NASA's INSTEP program, is developing a non-invasive, self-contained sensor system which can provide quantitative measurements of joint angles and muscle fatigue in the hand and forearm. The goal of this project is to develop a system with which hand/forearm motion and fatigue metrics can be determined in various terrestrial and zero-G work environments. A preliminary study of the prototype sensor systems and data reduction techniques for the fatigue measurement system are presented. The sensor systems evaluated include fiberoptics, used to measure joint angle, surface electrodes, which measure the electrical signals created in muscle as it contracts; microphones, which measure the noise made by contracting muscle; and accelerometers, which measure the lateral muscle acceleration during contraction. The prototype sensor systems were used to monitor joint motion of the metacarpophalangeal joint and muscle fatigue in flexor digitorum superficialis and flexor carpi ulnaris in subjects performing gripping tasks. Subjects were asked to sustain a 60-second constant-contraction (isometric) exercise and subsequently to perform a repetitive handgripping task to failure. Comparison of the electrical and mechanical signals of the muscles during the different tasks will be used to evaluate the applicability of muscle signal measurement techniques developed for isometric contraction tasks to fatigue prediction in quasi-dynamic exercises. Potential data reduction schemes are presented.

GRIP Experiment 2010

NASA Image and Video Library

2010-08-14

Errol Korn, lower left, explains the dropsonde experiment to Janel Thomas, a University of Maryland Baltimore County (UMBC) graduate student, seated, as Bob Pasken, standing left, and Jeff Halverson, a GRIP project scientist from UMBC, look on inside NASA's DC-8 airplane, at Fort Lauderdale International Airport in Fort Lauderdale, Fla., Sunday, Aug. 15, 2010. The Genesis and Rapid Intensification Processes (GRIP) experiment is a NASA Earth science field experiment in 2010 that is being conducted to better understand how tropical storms form and develop into major hurricanes. Photo Credit: (NASA/Paul E. Alers)

ELECTROMAGNETIC APPARATUS FOR MOVING A ROD

DOEpatents

Young, J.N.

1958-04-22

An electromagnetic apparatus for moving a rod-like member in small steps in either direction is described. The invention has particular application in the reactor field where the reactor control rods must be moved only a small distance and where the use of mechanical couplings is impractical due to the high- pressure seals required. A neutron-absorbing rod is mounted in a housing with gripping uaits that engage the rod, and coils for magnetizing the gripping units to make them grip, shift, and release the rod are located outside the housing.

Effect of Low-Level Laser Therapy and Strength Training Protocol on Hand Grip by Dynamometry

PubMed Central

Barbosa, Rafael; Marcolino, Alexandre; Souza, Vitor; Bertolino, Guilherme; Fonseca, Marisa; Guirro, Rinaldo

2017-01-01

Introduction: The purpose of this study was to investigate the effect of low-level laser therapy (LLLT) – 660 nm and 904 nm - before grip strength protocol in healthy subjects. Methods: The study included 45 healthy volunteers with an average age of 22.7 (±1.4) years, subdivided into the following groups, control group: grip strength training associated with placebo LLLT; 660 nm group: LLLT (660 nm, 20 J/cm2, power of 30 mW, and beam area of 0.06 cm2, continuous, energy 1.2 J, and exposure time 40 seconds per point) before grip strength training and 904 nm group: LLLT (904 nm, 10 J/cm2, peak power of 70 W and 0.13 cm2 beam area, with pulsed beam 9.500 Hz and 30 seconds of exposure time per point and emitted energy 1.2 J) before grip strength training. The LLLT was timed to contact 10 points located in the region of the superficial and deep flexor muscles of the fingers, with a total energy of 12.0 J per session. For the strength training protocol, the volunteer exercised their fingers with the dominant hand on a small table, elbow flexed at 90°, forearm in neutral, using a light extension handle. The Oxford protocol was performed during four weeks. The grip strength was assessed using a dynamometer (Jamar™). The data were evaluated by the analysis of variance (ANOVA) statistical method. Results: In the comparison of intragroup evaluation, only the 904 nm group showed a difference compared to the baseline assessment after 4 weeks (P < 0.05), in the final intergroup evaluation, a difference was observed in the comparison between the control and 904 nm groups Conclusion: In conclusion, LLLT (904 nm) applied before resistance training was effective in gaining grip strength when compared to LLLT (660 nm) and isolated strength training after 4 weeks. PMID:29123629

Fastener starter tool

NASA Technical Reports Server (NTRS)

Chandler, Faith T. (Inventor); Arnett, Michael C. (Inventor); Garton, Harry L. (Inventor); Valentino, William D. (Inventor)

2003-01-01

A fastener starter tool includes a number of spring retention fingers for retaining a small part, or combination of parts. The tool has an inner housing, which holds the spring retention fingers, a hand grip, and an outer housing configured to slide over the inner housing and the spring retention fingers toward and away from the hand grip, exposing and opening, or respectively, covering and closing, the spring retention fingers. By sliding the outer housing toward (away from) the hand grip, a part can be released from (retained by) the tool. The tool may include replaceable inserts, for retaining parts, such as screws, and configured to limit the torque applied to the part, to prevent cross threading. The inner housing has means to transfer torque from the hand grip to the insert. The tool may include replaceable bits, the inner housing having means for transferring torque to the replaceable bit.

Average grip strength: a meta-analysis of data obtained with a Jamar dynamometer from individuals 75 years or more of age.

PubMed

Bohannon, Richard W; Bear-Lehman, Jane; Desrosiers, Johanne; Massy-Westropp, Nicola; Mathiowetz, Virgil

2007-01-01

Although strength diminishes with age, average values for grip strength have not been available heretofore for discrete strata after 75 years. The purpose of this meta-analysis was to provide average values for the left and right hands of men and women 75-79, 80-84, 85-89, and 90-99 years. Contributing to the analysis were 7 studies and 739 subjects with whom the Jamar dynamometer and standard procedures were employed. Based on the analysis, average values for the left and right hands of men and women in each age stratum were derived. The derived values can serve as a standard of comparison for individual patients. An individual whose grip strength is below the lower limit of the confidence intervals of each stratum can be confidently considered to have less than average grip strength.

GRIP Experiment 2010

NASA Image and Video Library

2017-12-08

Errol Korn, lower left, explains the dropsonde experiment to Janel Thomas, a University of Maryland Baltimore County (UMBC) graduate student, seated, as Bob Pasken, standing left, and Jeff Halverson, a GRIP project scientist from UMBC, look on inside NASA's DC-8 airplane, at Fort Lauderdale International Airport in Fort Lauderdale, Fla., Sunday, Aug. 15, 2010. The Genesis and Rapid Intensification Processes (GRIP) experiment is a NASA Earth science field experiment in 2010 that is being conducted to better understand how tropical storms form and develop into major hurricanes. Credit: NASA/Paul E. Alers To read more about the GRIP Mission go here or here for an interactive feature NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe. Follow us on Twitter Join us on Facebook

Variation in the ciliary neurotrophic factor gene and muscle strength in older Caucasian women.

PubMed

Arking, Dan E; Fallin, Daniele M; Fried, Linda P; Li, Tao; Beamer, Brock A; Xue, Qian Li; Chakravarti, Aravinda; Walston, Jeremy

2006-05-01

To determine whether genetic variants in the ciliary neurotrophic factor (CNTF) gene are associated with muscle strength in older women. Cross-sectional analysis of baseline data from the Women's Health and Aging Studies I (1992) and II (1994), complementary population-based studies. Twelve contiguous ZIP code areas in Baltimore, Maryland. Three hundred sixty-three Caucasian, community-dwelling women aged 70 to 79. Participants were genotyped at the CNTF locus for eight single nucleotide polymorphisms (SNPs), including the null allele rs1800169. The dependent variables were grip strength and the frailty syndrome, identified as presence of three or more of five frailty indicators (weakness, slowness, weight loss, low physical activity, exhaustion). In addition to genotypes, independent variables of body mass index (BMI) and osteoarthritis of the hands were included. Using multivariate linear regression, single SNP analysis identified five SNPs significantly associated with grip strength (P<.05), after adjusting for age, BMI, and osteoarthritis. Haplotype analysis was performed, and a single haplotype associated with grip strength was identified (P<.01). The rs1800169 null allele fully explained the association between this haplotype and grip strength under a recessive model, with individuals homozygous for the null allele exhibiting a 3.80-kg lower (95% confidence interval=1.01-6.58) grip strength. No association was seen between the CNTF null allele and frailty. Individuals homozygous for the CNTF null allele had significantly lower grip strength but did not exhibit overt frailty. Larger prospective studies are needed to confirm this finding and extend it to additional populations.

Quantification of functional hand grip using electromyography and inertial sensor-derived accelerations: clinical implications.

PubMed

Martin-Martin, Jaime; Cuesta-Vargas, Antonio I

2014-12-11

Assessing hand injury is of great interest given the level of involvement of the hand with the environment. Knowing different assessment systems and their limitations generates new perspectives. The integration of digital systems (accelerometry and electromyography) as a tool to supplement functional assessment allows the clinician to know more about the motor component and its relation to movement. Therefore, the purpose of this study was the kinematic and electromyography analysis during functional hand movements. Ten subjects carried out six functional movements (terminal pinch, termino-lateral pinch, tripod pinch, power grip, extension grip and ball grip). Muscle activity (hand and forearm) was measured in real time using electromyograms, acquired with the Mega ME 6000, whilst acceleration was measured using the AcceleGlove. Electrical activity and acceleration variables were recorded simultaneously during the carrying out of the functional movements. The acceleration outcome variables were the modular vectors of each finger of the hand and the palm. In the electromyography, the main variables were normalized by the mean and by the maximum muscle activity of the thenar region, hypothenar, first interosseous dorsal, wrist flexors, carpal flexors and wrist extensors. Knowing muscle behavior allows the clinician to take a more direct approach in the treatment. Based on the results, the tripod grip shows greater kinetic activity and the middle finger is the most relevant in this regard. Ball grip involves most muscle activity, with the thenar region playing a fundamental role in hand activity. Relating muscle activation, movements, individual load and displacement offers the possibility to proceed with rehabilitation by individual component.

Impact of mild versus moderate intensity aerobic walking exercise training on markers of bone metabolism and hand grip strength in moderate hemophilic A patients.

PubMed

Al-Sharif, Fadwa Al-Ghalib; Al-Jiffri, Osama Hussien; El-Kader, Shehab Mahmoud Abd; Ashmawy, Eman Mohamed

2014-03-01

Patients with hemophilia A have low bone density than healthy controls. It is now widely recognized that physical activity and sports are beneficial for patients with hemophilia. To compare the effects of mild and moderate intensity treadmill walking exercises on markers of bone metabolism and hand grip strength in male patients with moderate hemophilia A. Fifty male patients with moderate hemophilia, and age range from 25 to 45 years. The subjects were randomly assigned into 2 equal groups; the first group (A) received moderate intensity aerobic exercise training. The second group (B) received mild intensity aerobic exercise training. There was a 32.1% and 24.8% increase in mean values of serum calcium and hand grip strength respectively and 22.7 % reduction in mean values of parathyroid hormone in moderate exercise training group (A). While there was a 15.1 % and 15 % increase in mean values of Serum Calcium and Hand grip strength respectively and 10.3 % reduction in mean values of parathyroid hormone in mild exercise training group(B). The mean values of serum calcium and hand grip strength were significantly increased, while the mean values of parathyroid hormone were significantly decreased in both groups . There were significant differences between mean levels of the investigated parameters in group (A) and group (B) after treatment. Moderate intensity aerobic exercise training on treadmill is appropriate to improve markers of bone metabolism and hand grip strength in male patients with hemophilia A.

Influences of load characteristics on impaired control of grip forces in patients with cerebellar damage.

PubMed

Brandauer, B; Timmann, D; Häusler, A; Hermsdörfer, J

2010-02-01

Various studies showed a clear impairment of cerebellar patients to modulate grip force in anticipation of the loads resulting from movements with a grasped object. This failure corroborated the theory of internal feedforward models in the cerebellum. Cerebellar damage also impairs the coordination of multiple-joint movements and this has been related to deficient prediction and compensation of movement-induced torques. To study the effects of disturbed torque control on feedforward grip-force control, two self-generated load conditions with different demands on torque control-one with movement-induced and the other with isometrically generated load changes-were directly compared in patients with cerebellar degeneration. Furthermore the cerebellum is thought to be more involved in grip-force adjustment to self-generated loads than to externally generated loads. Consequently, an additional condition with externally generated loads was introduced to further test this hypothesis. Analysis of 23 patients with degenerative cerebellar damage revealed clear impairments in predictive feedforward mechanisms in the control of both self-generated load types. Besides feedforward control, the cerebellar damage also affected more reactive responses when the externally generated load destabilized the grip, although this impairment may vary with the type of load as suggested by control experiments. The present findings provide further support that the cerebellum plays a major role in predictive control mechanisms. However, this impact of the cerebellum does not strongly depend on the nature of the load and the specific internal forward model. Contributions to reactive (grip force) control are not negligible, but seem to be dependent on the physical characteristics of an externally generated load.

Deficits in Coordinative Bimanual Timing Precision in Children With Specific Language Impairment

PubMed Central

Goffman, Lisa; Zelaznik, Howard N.

2017-01-01

Purpose Our objective was to delineate components of motor performance in specific language impairment (SLI); specifically, whether deficits in timing precision in one effector (unimanual tapping) and in two effectors (bimanual clapping) are observed in young children with SLI. Method Twenty-seven 4- to 5-year-old children with SLI and 21 age-matched peers with typical language development participated. All children engaged in a unimanual tapping and a bimanual clapping timing task. Standard measures of language and motor performance were also obtained. Results No group differences in timing variability were observed in the unimanual tapping task. However, compared with typically developing peers, children with SLI were more variable in their timing precision in the bimanual clapping task. Nine of the children with SLI performed greater than 1 SD below the mean on a standardized motor assessment. The children with low motor performance showed the same profile as observed across all children with SLI, with unaffected unimanual and impaired bimanual timing precision. Conclusions Although unimanual timing is unaffected, children with SLI show a deficit in timing that requires bimanual coordination. We propose that the timing deficits observed in children with SLI are associated with the increased demands inherent in bimanual performance. PMID:28174821

Multi-Attribute Sequential Search

ERIC Educational Resources Information Center

Bearden, J. Neil; Connolly, Terry

2007-01-01

This article describes empirical and theoretical results from two multi-attribute sequential search tasks. In both tasks, the DM sequentially encounters options described by two attributes and must pay to learn the values of the attributes. In the "continuous" version of the task the DM learns the precise numerical value of an attribute when she…

The Role of Cue-Target Translation in Backward Inhibition of Attentional Set

ERIC Educational Resources Information Center

Houghton, George; Pritchard, Rhys; Grange, James A.

2009-01-01

Backward inhibition (BI) refers to a reaction time cost incurred when returning to a recently abandoned task compared to returning to a task not recently performed. The effect has been proposed to reflect an inhibitory mechanism that aids transition from one task to another. The question arises as to precisely what aspects of a task may be…

In the Grip of the Scorpion Claw

NASA Image and Video Library

2010-09-21

Gripped in the claw of the constellation Scorpius sits the reflection nebula DG 129, a cloud of gas and dust that reflects light from nearby, bright stars. This infrared view of the nebula was captured by NASA Wide-field Infrared Survey Explorer.

78 FR 47531 - Airworthiness Directives; Various Restricted Category Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-06

... Technology, Inc.; Hagglund Helicopters, LLC (previously Western International Aviation, Inc.); International.... This AD requires creating a component history card or equivalent record for each main rotor grip (grip....); California Department of Forestry; Garlick Helicopters, Inc.; Global Helicopter Technology, Inc.; Hagglund...