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.

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.

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.

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.

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.

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

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.

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

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.

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

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.

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.

Grip Force and 3D Push-Pull Force Estimation Based on sEMG and GRNN

PubMed Central

Wu, Changcheng; Zeng, Hong; Song, Aiguo; Xu, Baoguo

2017-01-01

The estimation of the grip force and the 3D push-pull force (push and pull force in the three dimension space) from the electromyogram (EMG) signal is of great importance in the dexterous control of the EMG prosthetic hand. In this paper, an action force estimation method which is based on the eight channels of the surface EMG (sEMG) and the Generalized Regression Neural Network (GRNN) is proposed to meet the requirements of the force control of the intelligent EMG prosthetic hand. Firstly, the experimental platform, the acquisition of the sEMG, the feature extraction of the sEMG and the construction of GRNN are described. Then, the multi-channels of the sEMG when the hand is moving are captured by the EMG sensors attached on eight different positions of the arm skin surface. Meanwhile, a grip force sensor and a three dimension force sensor are adopted to measure the output force of the human's hand. The characteristic matrix of the sEMG and the force signals are used to construct the GRNN. The mean absolute value and the root mean square of the estimation errors, the correlation coefficients between the actual force and the estimated force are employed to assess the accuracy of the estimation. Analysis of variance (ANOVA) is also employed to test the difference of the force estimation. The experiments are implemented to verify the effectiveness of the proposed estimation method and the results show that the output force of the human's hand can be correctly estimated by using sEMG and GRNN method. PMID:28713231

Grip Force and 3D Push-Pull Force Estimation Based on sEMG and GRNN.

PubMed

Wu, Changcheng; Zeng, Hong; Song, Aiguo; Xu, Baoguo

2017-01-01

The estimation of the grip force and the 3D push-pull force (push and pull force in the three dimension space) from the electromyogram (EMG) signal is of great importance in the dexterous control of the EMG prosthetic hand. In this paper, an action force estimation method which is based on the eight channels of the surface EMG (sEMG) and the Generalized Regression Neural Network (GRNN) is proposed to meet the requirements of the force control of the intelligent EMG prosthetic hand. Firstly, the experimental platform, the acquisition of the sEMG, the feature extraction of the sEMG and the construction of GRNN are described. Then, the multi-channels of the sEMG when the hand is moving are captured by the EMG sensors attached on eight different positions of the arm skin surface. Meanwhile, a grip force sensor and a three dimension force sensor are adopted to measure the output force of the human's hand. The characteristic matrix of the sEMG and the force signals are used to construct the GRNN. The mean absolute value and the root mean square of the estimation errors, the correlation coefficients between the actual force and the estimated force are employed to assess the accuracy of the estimation. Analysis of variance (ANOVA) is also employed to test the difference of the force estimation. The experiments are implemented to verify the effectiveness of the proposed estimation method and the results show that the output force of the human's hand can be correctly estimated by using sEMG and GRNN method.

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.

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.

Modeling of the interaction between grip force and vibration transmissibility of a finger.

PubMed

Wu, John Z; Welcome, Daniel E; McDowell, Thomas W; Xu, Xueyan S; Dong, Ren G

2017-07-01

It is known that the vibration characteristics of the fingers and hand and the level of grip action interacts when operating a power tool. In the current study, we developed a hybrid finger model to simulate the vibrations of the hand-finger system when gripping a vibrating handle covered with soft materials. The hybrid finger model combines the characteristics of conventional finite element (FE) models, multi-body musculoskeletal models, and lumped mass models. The distal, middle, and proximal finger segments were constructed using FE models, the finger segments were connected via three flexible joint linkages (i.e., distal interphalangeal joint (DIP), proximal interphalangeal joint (PIP), and metacarpophalangeal (MCP) joint), and the MCP joint was connected to the ground and handle via lumped parameter elements. The effects of the active muscle forces were accounted for via the joint moments. The bone, nail, and hard connective tissues were assumed to be linearly elastic whereas the soft tissues, which include the skin and subcutaneous tissues, were considered as hyperelastic and viscoelastic. The general trends of the model predictions agree well with the previous experimental measurements in that the resonant frequency increased from proximal to the middle and to the distal finger segments for the same grip force, that the resonant frequency tends to increase with increasing grip force for the same finger segment, especially for the distal segment, and that the magnitude of vibration transmissibility tends to increase with increasing grip force, especially for the proximal segment. The advantage of the proposed model over the traditional vibration models is that it can predict the local vibration behavior of the finger to a tissue level, while taking into account the effects of the active musculoskeletal force, the effects of the contact conditions on vibrations, the global vibration characteristics. Published by Elsevier Ltd.

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

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.

Effects of hyperthyroidism on hand grip strength and function.

PubMed

Erkol İnal, Esra; Çarlı, Alparslan Bayram; Çanak, Sultan; Aksu, Oğuzhan; Köroğlu, Banu Kale; Savaş, Serpil

2015-01-01

Hyperthyroidism is a pathologic condition in which the body is exposed to excessive amounts of circulating thyroid hormones. Skeletal muscle is one of the major target organs of thyroid hormones. We evaluated hand grip strength and function in patients with overt hyperthyroidism. Fifty-one patients newly diagnosed with hyperthyroidism and 44 healthy controls participated in this study. Age, height, weight, and dominant hand of all participants were recorded. The diagnosis of hyperthyroidism was confirmed by clinical examination and laboratory tests. Hand grip strength was tested at the dominant hand with a Jamar hand dynamometer. The grooved pegboard test (PGT) was used to evaluate hand dexterity. The Duruöz Hand Index (DHI) was used to assess hand function. No significant differences were found in terms of clinical and demographic findings between the patients with hyperthyroidism and healthy controls (p > 0.05). Significant differences were found between the patients with hyperthyroidism and healthy controls regarding PGT and DHI scores (p < 0.05). Hyperthyroidism seemed to affect hand dexterity and function more than hand grip strength and seemed to be associated with reduced physical function more than muscle strength. This may also indicate that patients with hyperthyroidism should be evaluated by multidisplinary modalities.

[Reliability and validity of the analysis of hand grip and pinch force in isometric and isokinetic conditions].

PubMed

Benaglia, P G; Franchignoni, F; Ferriero, G; Zebellin, G; Sartorio, F

1999-01-01

Strength measurement of the hand grip is at the core of most protocols of functional assessment of the upper limb and in rehabilitation plays a major role in the analysis of treatment efficacy and patients' occupational ability. The aims of this study were to: a) verify the repeatability of strength measurements made during performance of the hand grip and three types of pinch, carried out under isometric and isokinetic conditions; b) compare maximal isometric strength with the corresponding isokinetic value for each of the manoeuvres studied; c) investigate the correlations between the strength expressed in the different manoeuvres, under both isometric and isokinetic conditions. We studied 14 voluntary subjects over three sessions conducted at 48-hr intervals, employing a computerized isokinetic dynamometer Lido WorkSet equipped with device N(o) 21 for the study of pinch (lateral pinch, pulp pinch, chuck pinch) and device N(o) 52 for the grip study. Isometric contractions resulted stronger than isokinetic ones, and the hand grip was found to be the manoeuvre able to produce most strength. The repeatability of each strength measurement test over the three days was high (Intraclass Correlation Coefficients: 0.89-0.93). Correlations between the isometric and isokinetic performance for each of the manoeuvres examined were always high (Pearson's r coefficients: 0.89-0.95) as were those between the different manoeuvres, whether performed in isometric or isokinetic modality (r: 0.60-0.94).

Investigation of index finger triggering force using a cadaver experiment: Effects of trigger grip span, contact location, and internal tendon force.

PubMed

Chang, Joonho; Freivalds, Andris; Sharkey, Neil A; Kong, Yong-Ku; Mike Kim, H; Sung, Kiseok; Kim, Dae-Min; Jung, Kihyo

2017-11-01

A cadaver study was conducted to investigate the effects of triggering conditions (trigger grip span, contact location, and internal tendon force) on index finger triggering force and the force efficiency of involved tendons. Eight right human cadaveric hands were employed, and a motion simulator was built to secure and control the specimens. Index finger triggering forces were investigated as a function of different internal tendon forces (flexor digitorum profundus + flexor digitorum superficialis = 40, 70, and 100 N), trigger grip spans (40, 50, and 60 mm), and contact locations between the index finger and a trigger. Triggering forces significantly increased when internal tendon forces increased from 40 to 100 N. Also, trigger grip spans and contact locations had significant effects on triggering forces; maximum triggering forces were found at a 50 mm span and the most proximal contact location. The results revealed that only 10-30% of internal tendon forces were converted to their external triggering forces. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

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.

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.

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.

Bilateral deficits in fine motor control and pinch grip force are not associated with electrodiagnostic findings in women with carpal tunnel syndrome.

PubMed

de la Llave-Rincón, Ana Isabel; Fernández-de-Las-Peñas, César; Pérez-de-Heredia-Torres, Marta; Martínez-Perez, Almudena; Valenza, Marie Carmen; Pareja, Juan A

2011-06-01

: The aim of this study was to analyze the differences in deficits in fine motor control and pinch grip force between patients with minimal, moderate/mild, or severe carpal tunnel syndrome (CTS) and healthy age- and hand dominance-matched controls. : A case-control study was conducted. The subtests of the Purdue Pegboard Test (one-hand and bilateral pin placements and assemblies) and pinch grip force between the thumb and the remaining four fingers of the hand were bilaterally evaluated in 66 women with minimal (n = 16), moderate (n = 16), or severe (n = 34) CTS and in 20 age- and hand-matched healthy women. The differences among the groups were analyzed using different mixed models of analysis of variance. : A two-way mixed analysis of variance revealed significant differences between groups, not depending on the presence of unilateral or bilateral symptoms (side), for the one-hand pin placement subtest: patients showed bilateral lower scores compared with controls (P < 0.001), without differences among those with minimal, moderate, or severe CTS (P = 0.946). The patients also exhibited lower scores in bilateral pin placement (P < 0.001) and assembly (P < 0.001) subtests, without differences among them. The three-way analysis of variance revealed significant differences among groups (P < 0.001) and fingers (P < 0.001), not depending on the presence of unilateral/bilateral symptoms (P = 0.684), for pinch grip force: patients showed bilateral lower pinch grip force in all fingers compared with healthy controls, without differences among those with minimal, moderate, or severe CTS. : The current study revealed similar bilateral deficits in fine motor control and pinch grip force in patients with minimal, moderate, or severe CTS, supporting that fine motor control deficits are a common feature of CTS not associated with electrodiagnostic findings.

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.

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.

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

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 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.

Hand-handle interface force and torque measurement system for pneumatic assembly tool operations: suggested enhancement to ISO 6544.

PubMed

Lin, Jia-Hua; McGorry, Raymond W; Chang, Chien-Chi

2007-05-01

A hand-handle interface force and torque measurement system is introduced to fill the void acknowledged in the international standard ISO 6544, which governs pneumatic, assembly tool reaction torque and force measurement. This system consists of an instrumented handle with a sensor capable of measuring grip force and reaction hand moment when threaded, fastener-driving tools are used by operators. The handle is rigidly affixed to the tool in parallel to the original tool handle allowing normal fastener-driving operations with minimal interference. Demonstration of this proposed system was made with tools of three different shapes: pistol grip, right angle, and in-line. During tool torque buildup, the proposed system measured operators exerting greater grip force on the soft joint than on the hard joint. The system also demonstrated that the soft joint demanded greater hand moment impulse than the hard joint. The results demonstrate that the measurement system can provide supplemental data useful in exposure assessment with power hand tools as proposed in ISO 6544.

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.

The effects of cold immersion and hand protection on grip strength.

PubMed

Vincent, M J; Tipton, M J

1988-08-01

The maximal voluntary grip strength (MVGS) of male volunteers was examined following a series of five intermittent 2 min cold water (5 degrees C) immersions of the unprotected hand or forearm. MVGS changes due to wearing a protective glove were also investigated. The surface electrical activity over the hand flexor muscles was recorded, as was the skin temperature of the hand and forearm. MVGS decreased significantly (p less than 0.01) following hand immersions (16%) and forearm immersion (13%). The majority of these reductions occurred during the first 2-min period of immersion. The effect of wearing a glove after unprotected hand cooling also produced significant (p less than 0.01) MVGS reductions which averaged 14%. These reductions were in addition to those caused by hand cooling. We conclude that both hand and forearm protection are important for the maintenance of hand-grip strength following cold water immersion.

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.

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.

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.

Grip preference, dermatoglyphics, and hand use in captive chimpanzees (Pan troglodytes).

PubMed

Hopkins, William D; Russell, Jamie L; Hostetter, Autumn; Pilcher, Dawn; Dahl, Jeremy F

2005-09-01

This paper examined the association between grip type, hand use, and fingerprint patterns in a sample of captive chimpanzees. Grip type for simple reaching was assessed for the left and right hand and classified as thumb-index, middle-index, or single-digit responses. Fingerprint patterns were characterized as whorls, loops, or arches on each finger. The results indicated that chimpanzees exhibit significantly more thumb-index responses for the right compared to the left hand. In addition, thumb-index responses were more prevalent for subjects that had a whorl compared to a loop or arch on their thumb. The results suggest that fingerprint patterns are associated with individual differences in grasping type in chimpanzees as well as some variation in hand use. (c) 2005 Wiley-Liss, Inc.

Grip Preference, Dermatoglyphics, and Hand Use in Captive Chimpanzees (Pan troglodytes)

PubMed Central

Hopkins, William D.; Russell, Jamie L.; Hostetter, Autumn; Pilcher, Dawn; Dahl, Jeremy F.

2007-01-01

This paper examined the association between grip type, hand use, and fingerprint patterns in a sample of captive chimpanzees. Grip type for simple reaching was assessed for the left and right hand and classified as thumb-index, middle-index, or single-digit responses. Fingerprint patterns were characterized as whorls, loops, or arches on each finger. The results indicated that chimpanzees exhibit significantly more thumb-index responses for the right compared to the left hand. In addition, thumb-index responses were more prevalent for subjects that had a whorl compared to a loop or arch on their thumb. The results suggest that fingerprint patterns are associated with individual differences in grasping type in chimpanzees as well as some variation in hand use. PMID:15761856

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

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

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.

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.

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.

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.

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.

The effect of hand dimensions, hand shape and some anthropometric characteristics on handgrip strength in male grip athletes and non-athletes.

PubMed

Fallahi, Ali Asghar; Jadidian, Ali Akbar

2011-09-01

It has been suggested that athletes with longer fingers and larger hand surfaces enjoy stronger grip power. Therefore, some researchers have examined a number of factors and anthropometric variables that explain this issue. To our knowledge, the data is scarce. Thus, the aim of this study was to investigate the effect of hand dimensions, hand shape and some anthropometric characteristics on handgrip strength in male grip athletes and non-athletes. 80 subjects aged between 19 and 29 participated in this study in two groups including: national and collegian grip athletes (n=40), and non-athletes (n=40). Body height and mass were measured to calculate body mass index. The shape of the dominant hand was drawn on a piece of paper with a thin marker so that finger spans, finger lengths, and perimeters of the hand could be measured. The hand shape was estimated as the ratio of the hand width to hand length. Handgrip strength was measured in the dominant and non-dominant hand using a standard dynamometer. Descriptive statistics were used for each variable and independent t test was used to analyze the differences between the two groups. The Pearson correlation coefficient test was used to evaluate the correlation between studied variables. Also, to predict important variables in handgrip strength, the linear trend was assessed using a linear regression analysis. There was a significant difference between the two groups in absolute handgrip strength (p<0.001) and handgrip/height ratio (p<0.001). The indices of body height, body mass, lean body mass and body fat content (p<0.001) were significantly greater in grip athletes. All hand variables except FS1-4 (p>0.05) were significantly different between the groups (p<0.001). After controlling body mass all hand anthropometric characteristics except thumb length (r=0.240, p= 0.135), hand shape (r=-0.029, p=0.858), middle finger length (r=0.305, p=0.056) and forearm circumference (r=0.162, p=0.319) significantly correlated with

The Effect of Hand Dimensions, Hand Shape and Some Anthropometric Characteristics on Handgrip Strength in Male Grip Athletes and Non-Athletes

PubMed Central

Fallahi, Ali Asghar; Jadidian, Ali Akbar

2011-01-01

It has been suggested that athletes with longer fingers and larger hand surfaces enjoy stronger grip power. Therefore, some researchers have examined a number of factors and anthropometric variables that explain this issue. To our knowledge, the data is scarce. Thus, the aim of this study was to investigate the effect of hand dimensions, hand shape and some anthropometric characteristics on handgrip strength in male grip athletes and non-athletes. 80 subjects aged between 19 and 29 participated in this study in two groups including: national and collegian grip athletes (n=40), and non-athletes (n=40). Body height and mass were measured to calculate body mass index. The shape of the dominant hand was drawn on a piece of paper with a thin marker so that finger spans, finger lengths, and perimeters of the hand could be measured. The hand shape was estimated as the ratio of the hand width to hand length. Handgrip strength was measured in the dominant and non-dominant hand using a standard dynamometer. Descriptive statistics were used for each variable and independent t test was used to analyze the differences between the two groups. The Pearson correlation coefficient test was used to evaluate the correlation between studied variables. Also, to predict important variables in handgrip strength, the linear trend was assessed using a linear regression analysis. There was a significant difference between the two groups in absolute handgrip strength (p<0.001) and handgrip/height ratio (p<0.001). The indices of body height, body mass, lean body mass and body fat content (p<0.001) were significantly greater in grip athletes. All hand variables except FS1-4 (p>0.05) were significantly different between the groups (p<0.001). After controlling body mass all hand anthropometric characteristics except thumb length (r=0.240, p= 0.135), hand shape (r=−0.029, p=0.858), middle finger length (r=0.305, p=0.056) and forearm circumference (r=0.162, p=0.319) significantly correlated with

Determination the validity of the new developed Sport Experts® hand grip dynamometer, measuring continuity of force, and comparison with current Takei and Baseline® dynamometers.

PubMed

Güçlüöver, A; Kutlu, M; Ciğerci, A E; Esen, H T; Demirkan, E; Erdoğdu, M

2015-11-01

In this study the Sport Experts ™ brand of hand grip dynamometer, measuring the continuity of force with the new developed load cell technology, was compared with Takei and Baseline® dynamometers, the current in use. It was tried to determine the correlation between them. In a study with provides use of clinical, orthopedic and rehabilitative purposes in the athletes and patient populations, this developed dynamometer can provide useful data by observing the continuity of force. The sample of the study included 60 badminton players in 2010-2011; consisting of Turkish Junior National male players (N.=16, age: 16.8±1.5), Junior National female players (N.=14, age: 16.9±1.6), amateur level male players (N.=15, age: 16.3±0.8) and amateur level female players (N.=15, age: 16.1±0.6). ANOVA was used in the statistical methods in order to compare the hand grip strength made by different brands; Pearson's correlation coefficient was used to determine the relationship level between dynamometers. Furthermore, test-retest reliability analysis was completed the new developed expert dynamometer. There was no statistically significant difference in the comparison of the dynamometers (P>0.05). Besides, a highly significant relationship (r=0.95 to 0.96) was found among all three dynamometers. However, the reliability coefficient was found (Chronbachs α: 0.989, ICC:0.97, r=0.97), (P<0.01) for the new developed expert dynamometer. Comparison between the dynamometers and the statistical results obtained from the correlation relationships shows interchangeability of dynamometers. As a result, our observation of force continuity (progression) of the athlete and patient populations is thought to be important.

Electromyography Biofeedback Exergames to Enhance Grip Strength and Motivation.

PubMed

Garcia-Hernandez, Nadia; Garza-Martinez, Karen; Parra-Vega, Vicente

2018-02-01

Hand strength weakness affects the performance of most activities of daily living. This study aims to design, develop, and test an electromyography (EMG) biofeedback training system based on serious games to promote motivation and synchronization and proper work intensity in grip exercises for improving hand strength. An EMG surface sensor, soft balls with different stiffness and three exergames, conforms the system to drive videogame clues in response to EMG-inferred grip strength, while overseeing motivation. An experiment was designed to study the effect of performing handgrip (HG) exercises with the proposed system versus traditional exercises. Participants, organized into two groups, followed a training program for each hand. One group followed a HG exergame training (ET) with the dominant hand and traditional HG training with the nondominant hand and inverse sequence by the second group. Initial and final grip forces were measured using a digital dynamometer. Questionnaires evaluated motivation and user experience, and exercise performance was evaluated in terms of work and rest time percentage and maximal voluntary contraction percentage over contraction periods. Data were analyzed for statistically significant differences and increase of means. Participants showed significantly better exercise performance and higher grip forces, with sustained intrinsic motivation and user experience, with the ET. Improvement in force level arises evidently from the synchronized work-rest time pattern and appropriated intensity of the muscle activity. This leads to support that EMG biofeedback exergames improve motor neurons firing and resting.

Real time relationship between individual finger force and grip exertion on distal phalanges in linear force following tasks.

PubMed

Luo, Shi-Jian; Shu, Ge; Gong, Yan

2018-05-01

Individual finger force (FF) in a grip task is a vital concern in rehabilitation engineering and precise control of manipulators because disorders in any of the fingers will affect the stability or accuracy of the grip force (GF). To understand the functions of each finger in a dynamic grip exertion task, a GF following experiment with four individual fingers without thumb was designed. This study obtained four individual FFs from the distal phalanges with a cylindrical handle in dynamic GF following tasks. Ten healthy male subjects with similar hand sizes participated in the four-finger linear GF following tasks at different submaximal voluntary contraction (SMVC) levels. The total GF, individual FF, finger force contribution, and following error were subsequently calculated and analyzed. The statistics indicated the following: 1) the accuracy and stability of GF at low %MVC were significantly higher than those at high SMVC; 2) at low SMVC, the ability of the fingers to increase the GF was better than the ability to reduce it, but it was contrary at high SMVC; 3) when the target wave (TW) was changing, all four fingers strongly participated in the force exertion, but the participation of the little finger decreased significantly when TW remained stable; 4) the index finger and ring finger had a complementary relationship and played a vital role in the adjustment and control of GF. The middle finger and little finger had a minor influence on the force control and adjustment. In conclusion, each of the fingers had different functions in a GF following task. These findings can be used in the assessment of finger injury rehabilitation and for algorithms of precise control. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

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.

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.

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

Force feedback delay affects perception of stiffness but not action, and the effect depends on the hand used but not on the handedness.

PubMed

Leib, Raz; Rubin, Inbar; Nisky, Ilana

2018-05-16

Interaction with an object often requires the estimation of its mechanical properties. We examined whether the hand that is used to interact with the object and their handedness affected people's estimation of these properties using stiffness estimation as a test case. We recorded participants' responses on a stiffness discrimination of a virtual elastic force field and the grip force applied on the robotic device during the interaction. In half of the trials, the robotic device delayed the participants' force feedback. Consistent with previous studies, delayed force feedback biased the perceived stiffness of the force field. Interestingly, in both left-handed and right-handed participants, for the delayed force field, there was even less perceived stiffness when participants used their left hand than their right hand. This result supports the idea that haptic processing is affected by laterality in the brain, not by handedness. Consistent with previous studies, participants adjusted their applied grip force according to the correct size and timing of the load force regardless of the hand that was used, the handedness, or the delay. This suggests that in all these conditions, participants were able to form an accurate internal representation of the anticipated trajectory of the load force (size and timing) and that this representation was used for accurate control of grip force independently of the perceptual bias. Thus, these results provide additional evidence for the dissociation between action and perception in the processing of delayed information.

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.

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

Mechanical impedance and absorbed power of hand-arm under x(h)-axis vibration and role of hand forces and posture.

PubMed

Aldien, Yasser; Marcotte, Pierre; Rakheja, Subhash; Boileau, Paul-Emile

2005-07-01

The biodynamic responses of the hand-arm system under x(h)-axis vibration are investigated in terms of the driving point mechanical impedance (DPMI) and absorbed power in a laboratory study. For this purpose, seven healthy male subjects are exposed to two levels of random vibration in the 8-1,000 Hz frequency range, using three instrumented cylindrical handles of different diameters (30, 40 and 50 mm), and different combinations of grip (10, 30 and 50 N) and push (0, 25 and 50 N) forces. The experiments involve grasping the handle while adopting two different postures, involving elbow flexion of 90 degrees and 180 degrees, with wrist in the neutral position for both postures. The analyses of the results revealed peak DPMI magnitude and absorbed power responses near 25 Hz and 150 Hz, for majority of the test conditions considered. The frequency corresponding to the peak response increased with increasing hand forces. Unlike the absorbed power, the DPMI response was mostly observed to be insensitive to variations in the excitation magnitude. The handle diameter revealed obvious effects on the DPMI magnitude, specifically at frequencies above 250 Hz, which was not evident in the absorbed power due to relatively low velocity at higher frequencies. The influence of hand forces was also evident on the DPMI magnitude response particularly at frequencies. above 100 Hz, while the effect of hand-arm posture on the DPMI magnitude was nearly negligible. The magnitude of power absorbed within the hand and arm was observed to be strongly dependent upon the excitation level over the entire frequency range, while the influence of hand-arm posture on the total absorbed power was observed to be important. The effect of variations in the hand forces on the absorbed power was relatively small for the bent elbow posture, while an increase in either the grip or the push force coupled with the extended arm posture resulted in considerably higher energy absorption. The results suggested

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.

Contribution of the Cerebellum in Cue-Dependent Force Changes During an Isometric Precision Grip Task.

PubMed

Kutz, Dieter F; Schmid, Barbara C; Meindl, Tobias; Timmann, Dagmar; Kolb, Florian P

2016-08-01

The "raspberry task" represents a precision grip task that requires continuous adjustment of grip forces and pull forces. During this task, subjects use a specialised grip rod and have to increase the pull force linearly while the rod is locked. The positions of the fingers are unrestrained and freely selectable. From the finger positions and the geometry of the grip rod, a physical lever was derived which is a comprehensive measurement of the subject's grip behaviour. In this study, the involvement of the cerebellum in establishing cued force changes (CFC) was examined. The auditory stimulus was associated with a motor behaviour that has to be readjusted during an ongoing movement that already started. Moreover, cerebellar involvement on grip behaviour was examined. The results show that patients presenting with degenerating cerebellar disease (CBL) were able to elicit CFC and were additionally able to optimise grip behaviour by minimising the lever. Comparison of the results of CBL with a control group of healthy subjects showed, however, that the CFC incidence was significantly lower and the reduction of the lever was less in CBL. Hence, the cerebellum is involved not only in the classical conditioning of reflexes but also in the association of sensory stimuli with complex changes in motor behaviour. Furthermore, the cerebellum is involved in the optimisation of grip behaviour during ongoing movements. Recent studies lead to the assumption that the cerebello-reticulo-spinal pathway might be important for the reduced optimisation of grip behaviour in CBL.

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…

Review and Evaluation of Hand-Arm Coordinate Systems for Measuring Vibration Exposure, Biodynamic Responses, and Hand Forces.

PubMed

Dong, Ren G; Sinsel, Erik W; Welcome, Daniel E; Warren, Christopher; Xu, Xueyan S; McDowell, Thomas W; Wu, John Z

2015-09-01

The hand coordinate systems for measuring vibration exposures and biodynamic responses have been standardized, but they are not actually used in many studies. This contradicts the purpose of the standardization. The objectives of this study were to identify the major sources of this problem, and to help define or identify better coordinate systems for the standardization. This study systematically reviewed the principles and definition methods, and evaluated typical hand coordinate systems. This study confirms that, as accelerometers remain the major technology for vibration measurement, it is reasonable to standardize two types of coordinate systems: a tool-based basicentric (BC) system and an anatomically based biodynamic (BD) system. However, these coordinate systems are not well defined in the current standard. Definition of the standard BC system is confusing, and it can be interpreted differently; as a result, it has been inconsistently applied in various standards and studies. The standard hand BD system is defined using the orientation of the third metacarpal bone. It is neither convenient nor defined based on important biological or biodynamic features. This explains why it is rarely used in practice. To resolve these inconsistencies and deficiencies, we proposed a revised method for defining the realistic handle BC system and an alternative method for defining the hand BD system. A fingertip-based BD system for measuring the principal grip force is also proposed based on an important feature of the grip force confirmed in this study.

Evaluation of pliers' grip spans in the maximum gripping task and sub-maximum cutting task.

PubMed

Kim, Dae-Min; Kong, Yong-Ku

2016-12-01

A total of 25 males participated to investigate the effects of the grip spans of pliers on the total grip force, individual finger forces and muscle activities in the maximum gripping task and wire-cutting tasks. In the maximum gripping task, results showed that the 50-mm grip span had significantly higher total grip strength than the other grip spans. In the cutting task, the 50-mm grip span also showed significantly higher grip strength than the 65-mm and 80-mm grip spans, whereas the muscle activities showed a higher value at 80-mm grip span. The ratios of cutting force to maximum grip strength were also investigated. Ratios of 30.3%, 31.3% and 41.3% were obtained by grip spans of 50-mm, 65-mm, and 80-mm, respectively. Thus, the 50-mm grip span for pliers might be recommended to provide maximum exertion in gripping tasks, as well as lower maximum-cutting force ratios in the cutting tasks.

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.

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.

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.

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.

Computer vision-based classification of hand grip variations in neurorehabilitation.

PubMed

Zariffa, José; Steeves, John D

2011-01-01

The complexity of hand function is such that most existing upper limb rehabilitation robotic devices use only simplified hand interfaces. This is in contrast to the importance of the hand in regaining function after neurological injury. Computer vision technology has been used to identify hand posture in the field of Human Computer Interaction, but this approach has not been translated to the rehabilitation context. We describe a computer vision-based classifier that can be used to discriminate rehabilitation-relevant hand postures, and could be integrated into a virtual reality-based upper limb rehabilitation system. The proposed system was tested on a set of video recordings from able-bodied individuals performing cylindrical grasps, lateral key grips, and tip-to-tip pinches. The overall classification success rate was 91.2%, and was above 98% for 6 out of the 10 subjects. © 2011 IEEE

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

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

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

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

Hand grip strength and maximum peak expiratory flow: determinants of bone mineral density of adolescent students.

PubMed

Cossio-Bolaños, Marco; Lee-Andruske, Cynthia; de Arruda, Miguel; Luarte-Rocha, Cristian; Almonacid-Fierro, Alejandro; Gómez-Campos, Rossana

2018-03-02

Maintaining and building healthy bones during the lifetime requires a complicated interaction between a number of physiological and lifestyle factors. Our goal of this study was to analyze the association between hand grip strength and the maximum peak expiratory flow with bone mineral density and content in adolescent students. The research team studied 1427 adolescent students of both sexes (750 males and 677 females) between the ages of 11.0 and 18.9 years in the Maule Region of Talca (Chile). Weight, standing height, sitting height, hand grip strength (HGS), and maximum peak expiratory flow (PEF) were measured. Furthermore, bone mineral density (BMD) and total body bone mineral content (BMC) were determined by using the Dual-Energy X-Ray Absorptiometry (DXA). Hand grip strength and PEF were categorized in tertiles (lowest, middle, and highest). Linear regression was performed in steps to analyze the relationship between the variables. Differences between categories were determined through ANOVA. In males, the hand grip strength explained 18-19% of the BMD and 20-23% of the BMC. For the females, the percentage of variation occurred between 12 and 13% of the BMD and 17-18% of the BMC. The variation of PEF for the males was observed as 33% of the BMD and 36% of the BMC. For the females, both the BMD and BMC showed a variation of 19%. The HGS and PEF were divided into three categories (lowest, middle, and highest). In both cases, significant differences occurred in bone density health between the three categories. In conclusion, the HGS and the PEF related positively to the bone density health of both sexes of adolescent students. The adolescents with poor values for hand grip strength and expiratory flow showed reduced values of BMD and BMC for the total body. Furthermore, the PEF had a greater influence on bone density health with respect to the HGS of the adolescents of both sexes.

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

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.

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.

Fast-adapting mechanoreceptors are important for force control in precision grip but not for sensorimotor memory.

PubMed

Park, Susanna B; Davare, Marco; Falla, Marika; Kennedy, William R; Selim, Mona M; Wendelschafer-Crabb, Gwen; Koltzenburg, Martin

2016-06-01

Sensory feedback from cutaneous mechanoreceptors in the fingertips is important in effective object manipulation, allowing appropriate scaling of grip and load forces during precision grip. However, the role of mechanoreceptor subtypes in these tasks remains incompletely understood. To address this issue, psychophysical tasks that may specifically assess function of type I fast-adapting (FAI) and slowly adapting (SAI) mechanoreceptors were used with object manipulation experiments to examine the regulation of grip force control in an experimental model of graded reduction in tactile sensitivity (healthy volunteers wearing 2 layers of latex gloves). With gloves, tactile sensitivity decreased significantly from 1.9 ± 0.4 to 12.3 ± 2.2 μm in the Bumps task assessing function of FAI afferents but not in a grating orientation task assessing SAI afferents (1.6 ± 0.1 to 1.8 ± 0.2 mm). Six axis force/torque sensors measured peak grip (PGF) and load (PLF) forces generated by the fingertips during a grip-lift task. With gloves there was a significant increase of PGF (14 ± 6%), PLF (17 ± 5%), and grip and load force rates (26 ± 8%, 20 ± 8%). A variable-weight series task was used to examine sensorimotor memory. There was a 20% increase in PGF when the lift of a light object was preceded by a heavy relative to a light object. This relationship was not significantly altered when lifting with gloves, suggesting that the addition of gloves did not change sensorimotor memory effects. We conclude that FAI fibers may be important for the online force scaling but not for the buildup of a sensorimotor memory. Copyright © 2016 the American Physiological Society.

Prevalence of hand osteoarthritis and its relationship to hand pain and grip strength in Japan: The third survey of the ROAD study.

PubMed

Kodama, Rie; Muraki, Shigeyuki; Oka, Hiroyuki; Iidaka, Toshiko; Teraguchi, Masatoshi; Kagotani, Ryohei; Asai, Yoshiki; Yoshida, Munehito; Morizaki, Yutaka; Tanaka, Sakae; Kawaguchi, Hiroshi; Nakamura, Kozo; Akune, Toru; Yoshimura, Noriko

2016-09-01

To examine the prevalence and pattern of hand osteoarthritis (HOA), and determine its relationship with grip strength and hand pain. Among the participants of the third survey of the Research on Osteoarthritis/Osteoporosis Against Disability (ROAD) study, 507 Japanese men and 1028 Japanese women were included. Radiographs of both hands were graded for osteoarthritis (OA) using the modified Kellgren-Lawrence (KL) scale. HOA was defined as the presence of at least one affected joint. The absence or presence of subchondral erosion was also scored. The prevalence of HOA (KL grade ≥2) was 89.9% in men and 92.3% in women (p = 0.11), and it was significantly associated with age. OA in the distal interphalangeal (DIP) joint was the highest overall. After adjusting for age, sex, body mass index, and the residing area, both severity (KL grade ≥3) and erosion were significantly related to low grip strength and hand pain. With regard to the joint groups, severe OA in the DIP and first carpometacarpal joints were related to hand pain. This study showed a high prevalence of radiographic HOA and a significant relationship between hand pain and the severity of HOA, in addition to erosion.

The influence of cooling forearm/hand and gender on estimation of handgrip strength.

PubMed

Cheng, Chih-Chan; Shih, Yuh-Chuan; Tsai, Yue-Jin; Chi, Chia-Fen

2014-01-01

Handgrip strength is essential in manual operations and activities of daily life, but the influence of forearm/hand skin temperature on estimation of handgrip strength is not well documented. Therefore, the present study intended to investigate the effect of local cooling of the forearm/hand on estimation of handgrip strength at various target force levels (TFLs, in percentage of MVC) for both genders. A cold pressor test was used to lower and maintain the hand skin temperature at 14°C for comparison with the uncooled condition. A total of 10 male and 10 female participants were recruited. The results indicated that females had greater absolute estimation deviations. In addition, both genders had greater absolute deviations in the middle range of TFLs. Cooling caused an underestimation of grip strength. Furthermore, a power function is recommended for establishing the relationship between actual and estimated handgrip force. Statement of relevance: Manipulation with grip strength is essential in daily life and the workplace, so it is important to understand the influence of lowering the forearm/hand skin temperature on grip-strength estimation. Females and the middle range of TFL had greater deviations. Cooling the forearm/hand tended to cause underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force. Practitioner Summary: It is important to understand the effect of lowering the forearm/hand skin temperature on grip-strength estimation. A cold pressor was used to cool the hand. The cooling caused underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force. Manipulation with grip strength is essential in daily life and the workplace, so it is important to understand the influence of lowering the forearm/hand skin temperature on grip-strength estimation. Females and the middle range of TFL had greater deviations. Cooling the

Smoking impact on grip strength and fatigue resistance: implications for exercise and hand therapy practice.

PubMed

Al-Obaidi, Saud; Al-Sayegh, Nowall; Nadar, Mohammed

2014-07-01

Grip strength assessment reflects on overall health of the musculoskeletal system and is a predictor of functional prognosis and mortality. The purpose of this study was: examine whether grip-strength and fatigue resistance are impaired in smokers, determine if smoking-related impairments (fatigue-index) can be predicted by demographic data, duration of smoking, packets smoked-per-day, and physical activity. Maximum isometric grip strength (MIGS) of male smokers (n = 111) and nonsmokers (n = 66) was measured before/after induced fatigue using Jamar dynamometer at 5-handle positions. Fatigue index was calculated based on percentage change in MIGS initially and after induced fatigue. Number of repetitions to squeeze the soft rubber ball to induce fatigue was significantly lower in smokers compared with nonsmokers (t = 10.6, P < .001 dominant hand; t = 13.9, P < .001 nondominant), demonstrating a significantly higher fatigue-index for smokers than nonsmokers (t = -8.7, P < .001 dominant hand; t = -6.0, P < .001 nondominant). The effect of smoking status on MIGS scores was significantly different between smokers and nonsmokers after induced fatigue (β = -3.98, standard error = 0.59, P < .001) where smokers experienced on average a reduction of nearly 4 MIGS less than nonsmokers before fatigue. Smoking status was the strongest significant independent predictor of the fatigue-index. Smokers demonstrated reduced grip strength and fast fatigability in comparison with nonsmokers.

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.

MusicGlove: motivating and quantifying hand movement rehabilitation by using functional grips to play music.

PubMed

Friedman, Nizan; Chan, Vicky; Zondervan, Danny; Bachman, Mark; Reinkensmeyer, David J

2011-01-01

People with stroke typically must perform much of their hand exercise at home without professional assistance as soon as two weeks after the stroke. Without feedback and encouragement, individuals often lose motivation to practice using the affected hand, and this disuse contributes to further declines in hand function. We developed the MusicGlove as a way to facilitate and motivate at home practice of hand movement. This low-cost device uses music as an interactive and motivating medium to guide hand exercise and to quantitatively assess hand movement recovery. It requires the user to practice functional movements, including pincer grip, key-pinch grip, and finger-thumb opposition, by using those movements to play different musical notes, played along to songs displayed by an interactive computer game. We report here the design of the glove and the results of a single-session experiment with 10 participants with chronic stroke. We found that the glove is well suited for use by people with an impairment level quantified by a Box and Blocks score of at least around 7; that the glove can be used to obtain a measure of hand dexterity (% of notes hit) that correlates strongly with the Box and Blocks score; and that the incorporation of music into training significantly improved both objective measures of hand motor performance and self-ratings of motivation for training in the single session.

Force-independent distribution of correlated neural inputs to hand muscles during three-digit grasping.

PubMed

Poston, Brach; Danna-Dos Santos, Alessander; Jesunathadas, Mark; Hamm, Thomas M; Santello, Marco

2010-08-01

The ability to modulate digit forces during grasping relies on the coordination of multiple hand muscles. Because many muscles innervate each digit, the CNS can potentially choose from a large number of muscle coordination patterns to generate a given digit force. Studies of single-digit force production tasks have revealed that the electromyographic (EMG) activity scales uniformly across all muscles as a function of digit force. However, the extent to which this finding applies to the coordination of forces across multiple digits is unknown. We addressed this question by asking subjects (n = 8) to exert isometric forces using a three-digit grip (thumb, index, and middle fingers) that allowed for the quantification of hand muscle coordination within and across digits as a function of grasp force (5, 20, 40, 60, and 80% maximal voluntary force). We recorded EMG from 12 muscles (6 extrinsic and 6 intrinsic) of the three digits. Hand muscle coordination patterns were quantified in the amplitude and frequency domains (EMG-EMG coherence). EMG amplitude scaled uniformly across all hand muscles as a function of grasp force (muscle x force interaction: P = 0.997; cosines of angle between muscle activation pattern vector pairs: 0.897-0.997). Similarly, EMG-EMG coherence was not significantly affected by force (P = 0.324). However, coherence was stronger across extrinsic than that across intrinsic muscle pairs (P = 0.0039). These findings indicate that the distribution of neural drive to multiple hand muscles is force independent and may reflect the anatomical properties or functional roles of hand muscle groups.

Precision grip control while walking down a step in children with unilateral cerebral palsy

PubMed Central

Flament, Benoît; Arnould, Carlyne; Thonnard, Jean-Louis; Bleyenheuft, Yannick

2018-01-01

Aim To compare grip force (GF) and load force (LF) coordination while walking down a step between children with unilateral cerebral palsy (UCP) and typically developing (TD) children. Methods Twenty-five children with UCP (age 9.3±1.7 y) and 25 TD controls (age 9.4±2.1 y) walked down a step while holding a grip-lift manipulandum. Dynamic and temporal variables were analyzed. The maximum voluntary contraction (MVC) was also assessed. Results The temporal course was perturbed mainly in the more affected hand of children with UCP when compared to TD children because the increases in GF and LF onset occurred in a reversed order. Compared with the TD controls, the children with UCP presented higher LF values on both hands and a higher GF on the less affected hand. In children with UCP, the GF to LF adaptation was adequate on the less affected hand but overestimated on the more affected hand. Furthermore, children with UCP presented a lower MVC in the more affected hand, leading to a higher percentage of MVC used during the task. Interpretation Our findings highlight an anticipatory control of precision grip during a stepping down task in children with UCP that is adequate for the less affected hand but altered for the more affected hand. PMID:29390012

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

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.

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.

Development of force sensing circuit to determine the optimal force required for effective dynamic tripod grip/writing

NASA Astrophysics Data System (ADS)

Suraj S., S.; Kulkarni, Palash; Bokadia, Pratik; Ramanathan, Prabhu; Nageswaran, Sharmila

2018-04-01

Handwriting is a combination of fine motor perceptions and cognitive skills to produce words on paper. For writing, the most commonly used and recommended grip is the dynamic tripod grip. A child's handwriting starts developing during the times of pre-schooling and improves over time. While writing, children apply excessive force on the writing instrument. This force is exerted by their fingers and as per the law of reaction, the writing instruments tend to exert an equal and opposite force, that could damage the delicate soft tissue structures in their fingers and initiate cramps and pains. This condition is also prevalent in adults who tend to write for long hours under pressure. An example would be adolescence student during the exams. Clinically this condition is termed as `Writer's Cramp', which is usually characterized by muscle fatigue and pain in the fingers. By understanding and fixing the threshold of the force that should be exerted by the fingers while gripping the instrument, the pain can be controlled or avoided. This research aims in designing an electronic module which can help in understanding the threshold of pressure which is optimum enough to establish a better contact between the fingers and the instrument and should be capable of controlling or avoiding the pain. The design of FSR based electronic system is explained with its circuitry and results of initial testing is presented in this paper.

Short Term Microgravity Effect on Isometric Hand Grip and Precision Pinch Force with Visual and Propioceptive Feedback

NASA Astrophysics Data System (ADS)

Pastacaldi, P.; Bracciaferri, F.; Neri, G.; Porciani, M.; Zolesi, V.

Experiments executed on the upper limb are assuming increasing significance in the frame of the Human Physiology in space, for at least two reasons: -the upper limb is the principal means of locomotion for the subject living in aspace station -fatigue can have a significant effect the hand, for the ordinary work on board,and in particular for the extra-vehicular activities. The degradation of the performances affecting the muscular-skeletal apparatus can be easily recognized on the upper limb, by exerting specific scientific protocols, to be repeated through the permanence of the subject in weightlessness conditions. Also, the effectiveness of adequate counter-measures aimed to the reduction of calcium and muscular mass need to be verified, by means of specific assessments on the upper limb. Another aspect relevant to the effect of microgravity on the upper limb is associated with the alteration of the motor control programs due to the different gravity factor, affecting not only the bio-mechanics of the subject, but in general all his/her psycho- physical conditions, induced by the totally different environment. Specific protocols on the upper limb can facilitate the studies on learning mechanisms for the motor control. The results of such experiments can be transferred to the Earth, useful for treatment of subjects with local traumas or diseases of the Central Nervous System.In the frame of the mission of the Italian astronaut Roberto Vittori on board the International Space Station (ISS), the Italian Space Agency (ASI) has promoted the program "Marco Polo", with a number of experiments devoted to the study of the effect of microgravity on the human body. The experiment CHIRO ("Crew's Health: Investigation on Reduced Operability) is a part of the program. Its purpose is the determination of the influence of the altered gravity on the control of the grip force exerted by the hand or by a group of fingers and the adaptive behavior of this control through the

The Association Between Sleep Duration and Hand Grip Strength in Community-Dwelling Older Adults: The Yilan Study, Taiwan.

PubMed

Chen, Hsi-Chung; Hsu, Nai-Wei; Chou, Pesus

2017-04-01

Different pathomechanisms may underlie the age-related decline in muscle mass and muscle power in older adults. This study aimed to examine the independent relationship between sleep duration and muscle power. Older adults, aged 65 years and older, were randomly selected to participate in a community-based survey in Yilan city, Taiwan. Data on self-reported sleep duration, sociodemographic information, lifestyle, chronic medical and mental health conditions, sleep-related parameters, and anthropometric measurements were collected. Participants who slept ≤4 hr, 5 hr, 6-7 hr, 8 hr, and ≥9 hr were defined as shortest, short, mid-range, long, and longest sleepers, respectively. Muscle power was estimated using hand grip strength. A total of 1081 individuals participated. Their average age was 76.3 ± 6.1 years, and 59.4% were female. After controlling for covariates, including muscle mass of the upper extremities, both long (estimated mean [95% confidence interval, CI]: 19.2 [18.2-20.2], p = .03) and longest sleepers (estimated mean [95% CI]: 17.8 [16.4-19.2], p = .001) had weaker hand grip strength than mid-range sleepers (estimated mean [95% CI]: 20.9 [20.3-21.4]). When stratified by sex, the association between longest sleep duration and weaker hand grip strength was noted among men only. Older adults with long sleep duration had weaker hand grip strength irrespective of muscle mass. This finding suggests that decreased muscle power may mediate or confound the relationship between long sleep duration and adverse health outcomes. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

The Effects of Unit Exercises on the Hand Grip Strength of Arm Wrestlers

ERIC Educational Resources Information Center

Yonca, Sezer S.; Engin, Çelikel B.; Serdar, Yücel A.; Mustafa, Karadag; Yüksel, Savucu

2017-01-01

The aim of this research is to evaluate the change in the hand grip strength of the male arm wrestlers before and after a unit of exercise. The participants of the research consist of sportsmen (n=16) of Firat University arm wrestling team in 18-25 age group. Within the scope of the research, all of the tests and measurements (age, length, body…

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.

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.

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.

Effect of anaemia on hand grip strength, walking speed, functionality and 1 year mortality in older hospitalized patients.

PubMed

Joosten, Etienne; Detroyer, Elke; Milisen, Koen

2016-08-19

Anaemia is a common problem in hospitalized older patients and is recognized as a risk factor for a significant number of adverse outcomes. Data of the effect of anaemia on functional status during hospitalization and mortality after discharge are limited. Aim of the study is to examine whether there is an association between anaemia, hand grip strength, gait speed and basic activities of daily living (ADL) during hospitalization and mortality 1 year after discharge in geriatric patients. In a prospective study, data on age, sex, body mass index, Mini-Mental State Examination (MMSE), main clinical diagnosis, number of comorbidities, hand grip strength, gait speed, ADL, haemoglobin, C-reactive protein and estimated Glomerular filtration ratio (eGFR) were recorded in 220 older patients, admitted to the acute geriatric ward of a university hospital. Anaemia was defined as a haemoglobin level <13 g/dL for men and <12 g/dL for women and was further specified into severe (haemoglobin level <10 g/dL for both men and women) and moderate anaemia (haemoglobin between 10 and 12 g/dL for women and 10 and 13 g/dL for men). Gait speed (in meters per second) was calculated after a 4.5 m walk and hand grip strength (in kilogram) was assessed with a hydraulic hand dynamometer. Functionality was assessed in the six basic activities of daily living. Information about the vital status was obtained 1 year after discharge with a telephone call. Analysis of covariance (ANCOVA) was used to examine the effect of the anaemia status on the walking speed, hand grip strength and premorbid ADL index and logistic regression analysis was used to examine whether anaemia could be identified as risk factors for mortality 12 months after discharge. Overall, 106 (48 %) patients had anaemia. Hand-grip strength, gait speed and ADL score were not significantly different between anaemic and non-anaemic hospitalized geriatric patients. After adjustment for age, sex, body mass index, eGFR, MMSE

Vitamin D status predicts hand-grip strength in young adult women living in Auckland, New Zealand.

PubMed

von Hurst, P R; Conlon, C; Foskett, A

2013-07-01

The identification of the vitamin D receptor (VDR) in skeletal muscle tissue and research in muscle strength and development in VDR-null mice confirms a role for vitamin D in muscle function. The relationship between muscle strength and vitamin D status has been explored to some degree in older populations with regard to fall prevention, but there has been very little research in younger adults. This cross-sectional study considered the predictors of muscle strength in 137 young women (19-29 years) living in New Zealand. The following measurements were taken in the latter months of winter: plasma 25OHD, dominant (HGD) and non-dominant hand-grip (HGND) strength (hand-grip dynamometer), counter measure jump, and recreational physical activity (RPA) assessed from a recent physical activity questionnaire (RPAQ). Dietary intake was measured with a four-day food diary, and body composition using air displacement plethysmography. This was a relatively inactive group of women; total RPA ranged from 0 to 3.93h per week, mean (SD) 0.86(0.74) h, approximately 50% comprised outdoor activities. Mean 25OHD was 54(28)nmol/l, HGD and HGND were significantly different (t=6.049, p<0.001) at 27.3(5.8) and 25.6(5.7)kg respectively. Total RPA and 25OHD were entered into a linear regression model with handgrip strength as the dependent variable (Model R(2)=0.11, p=0.001 non-dominant, R(2)=0.13, p<0.001 dominant). Serum 25OHD was significantly associated with HGD (B(SE)=0.05(0.02), p=0.016) and HGND (B(SE)=0.04(0.02), p=0.019), independent of recreational physical activity. Recreational activity had an association with both hand-grip strength and serum 25OHD, and when each were adjusted to remove this association, 25OHD accounted for 4.3% of HGND and 4.5% of HGD. These results suggest that vitamin D status does have a small but significant association with hand-grip strength in this group of young women. Further investigation in this age group with a randomised controlled trial is

Isometric hand grip strength measured by the Nintendo Wii Balance Board - a reliable new method.

PubMed

Blomkvist, A W; Andersen, S; de Bruin, E D; Jorgensen, M G

2016-02-03

Low hand grip strength is a strong predictor for both long-term and short-term disability and mortality. The Nintendo Wii Balance Board (WBB) is an inexpensive, portable, wide-spread instrument with the potential for multiple purposes in assessing clinically relevant measures including muscle strength. The purpose of the study was to explore intrarater reliability and concurrent validity of the WBB by comparing it to the Jamar hand dynamometer. Intra-rater test-retest cohort design with randomized validity testing on the first session. Using custom WBB software, thirty old adults (69.0 ± 4.2 years of age) were studied for reproducibility and concurrent validity compared to the Jamar hand dynamometer. Reproducibility was tested for dominant and non-dominant hands during the same time-of-day, one week apart. Intraclass correlation coefficient (ICC) and standard error of measurement (SEM) and limits of agreement (LOA) were calculated to describe relative and absolute reproducibility respectively. To describe concurrent validity, Pearson's product-moment correlation and ICC was calculated. Reproducibility was high with ICC values of >0.948 across all measures. Both SEM and LOA were low (0.2-0.5 kg and 2.7-4.2 kg, respectively) in both the dominant and non-dominant hand. For validity, Pearson correlations were high (0.80-0.88) and ICC values were fair to good (0.763-0.803). Reproducibility for WBB was high for relative measures and acceptable for absolute measures. In addition, concurrent validity between the Jamar hand dynamometer and the WBB was acceptable. Thus, the WBB may be a valid instrument to assess hand grip strength in older adults.

Review and Evaluation of Hand–Arm Coordinate Systems for Measuring Vibration Exposure, Biodynamic Responses, and Hand Forces

PubMed Central

Dong, Ren G.; Sinsel, Erik W.; Welcome, Daniel E.; Warren, Christopher; Xu, Xueyan S.; McDowell, Thomas W.; Wu, John Z.

2015-01-01

The hand coordinate systems for measuring vibration exposures and biodynamic responses have been standardized, but they are not actually used in many studies. This contradicts the purpose of the standardization. The objectives of this study were to identify the major sources of this problem, and to help define or identify better coordinate systems for the standardization. This study systematically reviewed the principles and definition methods, and evaluated typical hand coordinate systems. This study confirms that, as accelerometers remain the major technology for vibration measurement, it is reasonable to standardize two types of coordinate systems: a tool-based basicentric (BC) system and an anatomically based biodynamic (BD) system. However, these coordinate systems are not well defined in the current standard. Definition of the standard BC system is confusing, and it can be interpreted differently; as a result, it has been inconsistently applied in various standards and studies. The standard hand BD system is defined using the orientation of the third metacarpal bone. It is neither convenient nor defined based on important biological or biodynamic features. This explains why it is rarely used in practice. To resolve these inconsistencies and deficiencies, we proposed a revised method for defining the realistic handle BC system and an alternative method for defining the hand BD system. A fingertip-based BD system for measuring the principal grip force is also proposed based on an important feature of the grip force confirmed in this study. PMID:26929824

Cross-talk in mechanomyographic signals from the forearm muscles during sub-maximal to maximal isometric grip force.

PubMed

Islam, Md Anamul; Sundaraj, Kenneth; Ahmad, R Badlishah; Sundaraj, Sebastian; Ahamed, Nizam Uddin; Ali, Md Asraf

2014-01-01

This study aimed: i) to examine the relationship between the magnitude of cross-talk in mechanomyographic (MMG) signals generated by the extensor digitorum (ED), extensor carpi ulnaris (ECU), and flexor carpi ulnaris (FCU) muscles with the sub-maximal to maximal isometric grip force, and with the anthropometric parameters of the forearm, and ii) to quantify the distribution of the cross-talk in the MMG signal to determine if it appears due to the signal component of intramuscular pressure waves produced by the muscle fibers geometrical changes or due to the limb tremor. Twenty, right-handed healthy men (mean ± SD: age  = 26.7±3.83 y; height  = 174.47±6.3 cm; mass  = 72.79±14.36 kg) performed isometric muscle actions in 20% increment from 20% to 100% of the maximum voluntary isometric contraction (MVIC). During each muscle action, MMG signals generated by each muscle were detected using three separate accelerometers. The peak cross-correlations were used to quantify the cross-talk between two muscles. The magnitude of cross-talk in the MMG signals among the muscle groups ranged from, R2(x, y) = 2.45-62.28%. Linear regression analysis showed that the magnitude of cross-talk increased linearly (r2 = 0.857-0.90) with the levels of grip force for all the muscle groups. The amount of cross-talk showed weak positive and negative correlations (r2 = 0.016-0.216) with the circumference and length of the forearm respectively, between the muscles at 100% MVIC. The cross-talk values significantly differed among the MMG signals due to: limb tremor (MMGTF), slow firing motor unit fibers (MMGSF) and fast firing motor unit fibers (MMGFF) between the muscles at 100% MVIC (p<0.05, η2 = 0.47-0.80). The results of this study may be used to improve our understanding of the mechanics of the forearm muscles during different levels of the grip force.

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.

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.

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

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.

Development of a Prototype Over-Actuated Biomimetic Prosthetic Hand

PubMed Central

Williams, Matthew R.; Walter, Wayne

2015-01-01

The loss of a hand can greatly affect quality of life. A prosthetic device that can mimic normal hand function is very important to physical and mental recuperation after hand amputation, but the currently available prosthetics do not fully meet the needs of the amputee community. Most prosthetic hands are not dexterous enough to grasp a variety of shaped objects, and those that are tend to be heavy, leading to discomfort while wearing the device. In order to attempt to better simulate human hand function, a dexterous hand was developed that uses an over-actuated mechanism to form grasp shape using intrinsic joint mounted motors in addition to a finger tendon to produce large flexion force for a tight grip. This novel actuation method allows the hand to use small actuators for grip shape formation, and the tendon to produce high grip strength. The hand was capable of producing fingertip flexion force suitable for most activities of daily living. In addition, it was able to produce a range of grasp shapes with natural, independent finger motion, and appearance similar to that of a human hand. The hand also had a mass distribution more similar to a natural forearm and hand compared to contemporary prosthetics due to the more proximal location of the heavier components of the system. This paper describes the design of the hand and controller, as well as the test results. PMID:25790306

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.

Size-weight illusion and anticipatory grip force scaling following unilateral cortical brain lesion.

PubMed

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

2011-04-01

The prediction of object weight from its size is an important prerequisite of skillful object manipulation. Grip and load forces anticipate object size during early phases of lifting an object. A mismatch between predicted and actual weight when two different sized objects have the same weight results in the size-weight illusion (SWI), the small object feeling heavier. This study explores whether lateralized brain lesions in patients with or without apraxia alter the size-weight illusion and impair anticipatory finger force scaling. Twenty patients with left brain damage (LBD, 10 with apraxia, 10 without apraxia), ten patients with right brain damage (RBD), and matched control subjects lifted two different-sized boxes in alternation. All subjects experienced a similar size-weight illusion. The anticipatory force scaling of all groups was in correspondence with the size cue: higher forces and force rates were applied to the big box and lower forces and force rates to the small box during the first lifts. Within few lifts, forces were scaled to actual object weight. Despite the lack of significant differences at group level, 5 out of 20 LBD patients showed abnormal predictive scaling of grip forces. They differed from the LBD patients with normal predictive scaling by a greater incidence of posterior occipito-parietal lesions but not by a greater incidence of apraxia. The findings do not support a more general role for the motor-dominant left hemisphere, or an influence of apraxia per se, in the scaling of finger force according to object properties. However, damage in the vicinity of the parietal-occipital junction may be critical for deriving predictions of weight from size. Copyright © 2011 Elsevier Ltd. All rights reserved.

The Impact of Hand Grip Strength Exercises on the Target Shooting Accuracy Score for Archers

ERIC Educational Resources Information Center

Sezer, Süreyya Yonca

2017-01-01

The purpose of this research is to investigate the impact of hand grip strength exercises on the target shooting accuracy score for male archers. Thirty male archers (n1 = 15, 19.85 ± 1.35, n2 = 15 19.71 ± 1.31) ranging 18-20 years old were included in our study from the archery team of the city of Elazig, department of youth sports. The…

Retraining and assessing hand movement after stroke using the MusicGlove: comparison with conventional hand therapy and isometric grip training

PubMed Central

2014-01-01

Background It is thought that therapy should be functional, be highly repetitive, and promote afferent input to best stimulate hand motor recovery after stroke, yet patients struggle to access such therapy. We developed the MusicGlove, an instrumented glove that requires the user to practice gripping-like movements and thumb-finger opposition to play a highly engaging, music-based, video game. The purpose of this study was to 1) compare the effect of training with MusicGlove to conventional hand therapy 2) determine if MusicGlove training was more effective than a matched form of isometric hand movement training; and 3) determine if MusicGlove game scores predict clinical outcomes. Methods 12 chronic stroke survivors with moderate hemiparesis were randomly assigned to receive MusicGlove, isometric, and conventional hand therapy in a within-subjects design. Each subject participated in six one-hour treatment sessions three times per week for two weeks, for each training type, for a total of 18 treatment sessions. A blinded rater assessed hand impairment before and after each training type and at one-month follow-up including the Box and Blocks (B & B) test as the primary outcome measure. Subjects also completed the Intrinsic Motivation Inventory (IMI). Results Subjects improved hand function related to grasping small objects more after MusicGlove compared to conventional training, as measured by the B & B score (improvement of 3.21±3.82 vs. -0.29±2.27 blocks; P=0.010) and the 9 Hole Peg test (improvement of 2.14±2.98 vs. -0.85±1.29 pegs/minute; P=0.005). There was no significant difference between training types in the broader assessment batteries of hand function. Subjects benefited less from isometric therapy than MusicGlove training, but the difference was not significant (P>0.09). Subjects sustained improvements in hand function at a one month follow-up, and found the MusicGlove more motivating than the other two therapies, as measured by the IMI. Music

Retraining and assessing hand movement after stroke using the MusicGlove: comparison with conventional hand therapy and isometric grip training.

PubMed

Friedman, Nizan; Chan, Vicky; Reinkensmeyer, Andrea N; Beroukhim, Ariel; Zambrano, Gregory J; Bachman, Mark; Reinkensmeyer, David J

2014-04-30

It is thought that therapy should be functional, be highly repetitive, and promote afferent input to best stimulate hand motor recovery after stroke, yet patients struggle to access such therapy. We developed the MusicGlove, an instrumented glove that requires the user to practice gripping-like movements and thumb-finger opposition to play a highly engaging, music-based, video game. The purpose of this study was to 1) compare the effect of training with MusicGlove to conventional hand therapy 2) determine if MusicGlove training was more effective than a matched form of isometric hand movement training; and 3) determine if MusicGlove game scores predict clinical outcomes. 12 chronic stroke survivors with moderate hemiparesis were randomly assigned to receive MusicGlove, isometric, and conventional hand therapy in a within-subjects design. Each subject participated in six one-hour treatment sessions three times per week for two weeks, for each training type, for a total of 18 treatment sessions. A blinded rater assessed hand impairment before and after each training type and at one-month follow-up including the Box and Blocks (B & B) test as the primary outcome measure. Subjects also completed the Intrinsic Motivation Inventory (IMI). Subjects improved hand function related to grasping small objects more after MusicGlove compared to conventional training, as measured by the B & B score (improvement of 3.21±3.82 vs. -0.29±2.27 blocks; P=0.010) and the 9 Hole Peg test (improvement of 2.14±2.98 vs. -0.85±1.29 pegs/minute; P=0.005). There was no significant difference between training types in the broader assessment batteries of hand function. Subjects benefited less from isometric therapy than MusicGlove training, but the difference was not significant (P>0.09). Subjects sustained improvements in hand function at a one month follow-up, and found the MusicGlove more motivating than the other two therapies, as measured by the IMI. MusicGlove games scores correlated

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

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.

Hand grip strength and anthropometric characteristics in Italian female national basketball teams.

PubMed

Pizzigalli, Luisa; Micheletti Cremasco, Margherita; LA Torre, Antonio; Rainoldi, Alberto; Benis, Roberto

2017-05-01

The aim of this study was to investigate the influence of hand and body dimensions on hand grip strength and to define a reference scale for talent identification in basketball players. Body and hand anthropometric data and the maximal handgrip strength of 109 female Italian basketball National players (Under14-Seniores) were measured. Handgrip strength and arm length trend increased, raising the statistical significant differences only for players from the age of 19 (U20, Seniores) with respect to sub-elite groups (U14, U15) (P<0.05). Handgrip strength showed low positive correlations with height and Body Mass Index but a positive relationships with arm length (r=0.5; P<0.001). Findings underline training and years of practice have effects on increasing handgrip strength. Data show that to select female basketball players by arm length means selecting by handgrip strength. Thus it is possible to suggest that in addition to height, arm length could also be considered a useful parameter in young female talent identification.

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 influence of grip on oxygen consumption and leg forces when using classical style roller skis.

PubMed

Ainegren, M; Carlsson, P; Laaksonen, M S; Tinnsten, M

2014-04-01

The purpose of this study was to investigate the influence of classical style roller skis' grip (static friction coefficients, μS) on cross-country skiers' oxygen consumption and leg forces during treadmill roller skiing, when using the diagonal stride and kick double poling techniques. The study used ratcheted wheel roller skis from the open market and a uniquely designed roller ski with an adjustable camber and grip function. The results showed significantly (P ≤ 0.05) higher oxygen consumption (∼ 14%), heart rate (∼ 7%), and lower propulsive forces from the legs during submaximal exercise and a shorter time to exhaustion (∼ 30%) in incremental maximal tests when using roller skis with a μS similar to on-snow skiing, while there was no difference between tests when using different pairs of roller skis with a similar, higher μS. Thus, we concluded that oxygen consumption (skiing economy), propulsive leg forces, and performance time are highly changed for the worse when using roller skis with a lower μS, such as for on-snow skiing with grip-waxed cross-country skis, in comparison to ratcheted wheel roller skis with several times higher μS. © 2012 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Sustained effect of resistance training on blood pressure and hand grip strength following a detraining period in elderly hypertensive women: a pilot study

PubMed Central

Nascimento, Dahan da Cunha; Tibana, Ramires Alsamir; Benik, Franklin M; Fontana, Keila Elizabeth; Neto, Frederico Ribeiro; de Santana, Frederico Santos; Santos-Neto, Leopoldo; Silva, Renato André Sousa; Silva, Alessandro Oliveira; Farias, Darlan Lopes; Balsamo, Sandor; Prestes, Jonato

2014-01-01

Introduction Hypertension is the most prevalent modifiable risk factor with a high prevalence among older adults. Exercise is a nonpharmacological treatment shown to benefit all patients with hypertension. Objective This study examined the effects of a 14-week moderate intensity resistance training program (RT) on the maintenance of blood pressure and hand grip strength during an extended detraining period in elderly hypertensive women. Methods Twelve hypertensive sedentary elderly women completed 14 weeks of whole body RT at a moderate perceived exertion following a detraining period of 14 weeks. Results Following the training period, participants demonstrated an increase in absolute hand grip strength (P=0.001), relative hand grip strength (P=0.032) and a decrease of systolic (P=0.001), diastolic (P=0.008), and mean blood pressure (P=0.002) when compared to pre-exercise values. In addition, these effects were sustained after 14 weeks of detraining. Conclusion Resistance training may be a valuable method to improve muscular strength and blood pressure in elderly people with benefits being maintained up to 14 weeks following training cessation. PMID:24477221

Hand function is altered in individuals with a history of illicit stimulant use.

PubMed

Pearson-Dennett, Verity; Flavel, Stanley C; Wilcox, Robert A; Thewlis, Dominic; Vogel, Adam P; White, Jason M; Todd, Gabrielle

2014-01-01

Use of illicit stimulant drugs such as methamphetamine, cocaine, and ecstasy are a significant worldwide problem. However, little is known about the effect of these drugs on movement. The aim of the current study was to investigate hand function in adults with a history of illicit stimulant use. We hypothesized that prior use of illicit stimulant drugs is associated with abnormal manipulation of objects. The study involved 22 subjects with a history of illicit stimulant use (aged 29±8 yrs; time since last use: 1.8±4.0 yrs) and two control groups comprising 27 non-drug users (aged 25±8 yrs) and 17 cannabis users with no history of stimulant use (aged 22±5 yrs). Each subject completed screening tests (neuropsychological assessment, medical history questionnaire, lifetime drug history questionnaire, and urine drug screen) prior to gripping and lifting a light-weight object with the dominant right hand. Horizontal grip force, vertical lift force, acceleration, and first dorsal interosseus electromyographic (EMG) activity were recorded during three trials. In trial one, peak grip force was significantly greater in the stimulant group (12.8±3.9 N) than in the control groups (non-drug: 10.3±4.6 N; cannabis: 9.4±2.9 N, P<0.022). However, peak grip force did not differ between groups in trials two and three. The results suggest that individuals with a history of stimulant use overestimate the grip force required to manipulate a novel object but, are able to adapt grip force in subsequent lifts. The results suggest that movement dysfunction may be an unrecognized consequence of illicit stimulant use.

Hand Function is Altered in Individuals with a History of Illicit Stimulant Use

PubMed Central

Pearson-Dennett, Verity; Flavel, Stanley C.; Wilcox, Robert A.; Thewlis, Dominic; Vogel, Adam P.; White, Jason M.; Todd, Gabrielle

2014-01-01

Use of illicit stimulant drugs such as methamphetamine, cocaine, and ecstasy are a significant worldwide problem. However, little is known about the effect of these drugs on movement. The aim of the current study was to investigate hand function in adults with a history of illicit stimulant use. We hypothesized that prior use of illicit stimulant drugs is associated with abnormal manipulation of objects. The study involved 22 subjects with a history of illicit stimulant use (aged 29±8 yrs; time since last use: 1.8±4.0 yrs) and two control groups comprising 27 non-drug users (aged 25±8 yrs) and 17 cannabis users with no history of stimulant use (aged 22±5 yrs). Each subject completed screening tests (neuropsychological assessment, medical history questionnaire, lifetime drug history questionnaire, and urine drug screen) prior to gripping and lifting a light-weight object with the dominant right hand. Horizontal grip force, vertical lift force, acceleration, and first dorsal interosseus electromyographic (EMG) activity were recorded during three trials. In trial one, peak grip force was significantly greater in the stimulant group (12.8±3.9 N) than in the control groups (non-drug: 10.3±4.6 N; cannabis: 9.4±2.9 N, P<0.022). However, peak grip force did not differ between groups in trials two and three. The results suggest that individuals with a history of stimulant use overestimate the grip force required to manipulate a novel object but, are able to adapt grip force in subsequent lifts. The results suggest that movement dysfunction may be an unrecognized consequence of illicit stimulant use. PMID:25545892

How Predictive Is Grip Force Control in the Complete Absence of Somatosensory Feedback?

ERIC Educational Resources Information Center

Nowak, Dennis A.; Glasauer, Stefan; Hermsdorfer, Joachim

2004-01-01

Grip force control relies on accurate internal models of the dynamics of our motor system and the external objects we manipulate. Internal models are not fixed entities, but rather are trained and updated by sensory experience. Sensory feedback signals relevant object properties and mechanical events, e.g. at the skin-object interface, to modify…

Priming for Improved Hand Strength in Persons with Chronic Tetraplegia: A Comparison of Priming-Augmented Functional Task Practice, Priming Alone, and Conventional Exercise Training

PubMed Central

Gomes-Osman, Joyce; Tibbett, Jacqueline A.; Poe, Brandon P.; Field-Fote, Edelle C.

2017-01-01

Many everyday tasks cannot be accomplished without adequate grip strength, and corticomotor drive to the spinal motoneurons is a key determinant of grip strength. In persons with tetraplegia, damage to spinal pathways limits transmission of signals from motor cortex to spinal motoneurons. Corticomotor priming, which increases descending drive, should increase corticospinal transmission through the remaining spinal pathways resulting in increased grip strength. Since the motor and somatosensory cortices share reciprocal connections, corticomotor priming may also have potential to influence somatosensory function. The purpose of this study was to assess changes in grip (precision, power) force and tactile sensation associated with two different corticomotor priming approaches and a conventional training approach and to determine whether baseline values can predict responsiveness to training. Participants with chronic (≥1 year) tetraplegia (n = 49) were randomized to one of two corticomotor priming approaches: functional task practice plus peripheral nerve somatosensory stimulation (FTP + PNSS) or PNSS alone, or to conventional exercise training (CET). To assess whether baseline corticospinal excitability (CSE) is predictive of responsiveness to training, in a subset of participants, we assessed pre-intervention CSE of the thenar muscles. Participants were trained 2 h daily, 5 days/week for 4 weeks. Thirty-seven participants completed the study. Following intervention, significant improvements in precision grip force were observed in both the stronger and weaker hand in the FTP + PNSS group (effect size: 0.51, p = 0.04 and 0.54, p = 0.03, respectively), and significant improvements in weak hand precision grip force were associated with both PNSS and CET (effect size: 0.54, p = 0.03 and 0.75, p = 0.02, respectively). No significant changes were observed in power grip force or somatosensory scores in any group. Across all groups

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.

Tool making, hand morphology and fossil hominins

PubMed Central

Marzke, Mary W.

2013-01-01

Was stone tool making a factor in the evolution of human hand morphology? Is it possible to find evidence in fossil hominin hands for this capability? These questions are being addressed with increasingly sophisticated studies that are testing two hypotheses; (i) that humans have unique patterns of grip and hand movement capabilities compatible with effective stone tool making and use of the tools and, if this is the case, (ii) that there exist unique patterns of morphology in human hands that are consistent with these capabilities. Comparative analyses of human stone tool behaviours and chimpanzee feeding behaviours have revealed a distinctive set of forceful pinch grips by humans that are effective in the control of stones by one hand during manufacture and use of the tools. Comparative dissections, kinematic analyses and biomechanical studies indicate that humans do have a unique pattern of muscle architecture and joint surface form and functions consistent with the derived capabilities. A major remaining challenge is to identify skeletal features that reflect the full morphological pattern, and therefore may serve as clues to fossil hominin manipulative capabilities. Hominin fossils are evaluated for evidence of patterns of derived human grip and stress-accommodation features. PMID:24101624

Tool making, hand morphology and fossil hominins.

PubMed

Marzke, Mary W

2013-11-19

Was stone tool making a factor in the evolution of human hand morphology? Is it possible to find evidence in fossil hominin hands for this capability? These questions are being addressed with increasingly sophisticated studies that are testing two hypotheses; (i) that humans have unique patterns of grip and hand movement capabilities compatible with effective stone tool making and use of the tools and, if this is the case, (ii) that there exist unique patterns of morphology in human hands that are consistent with these capabilities. Comparative analyses of human stone tool behaviours and chimpanzee feeding behaviours have revealed a distinctive set of forceful pinch grips by humans that are effective in the control of stones by one hand during manufacture and use of the tools. Comparative dissections, kinematic analyses and biomechanical studies indicate that humans do have a unique pattern of muscle architecture and joint surface form and functions consistent with the derived capabilities. A major remaining challenge is to identify skeletal features that reflect the full morphological pattern, and therefore may serve as clues to fossil hominin manipulative capabilities. Hominin fossils are evaluated for evidence of patterns of derived human grip and stress-accommodation features.

Imagined Hand Clenching Force and Speed Modulate Brain Activity and Are Classified by NIRS Combined With EEG.

PubMed

Fu, Yunfa; Xiong, Xin; Jiang, Changhao; Xu, Baolei; Li, Yongcheng; Li, Hongyi

2017-09-01

Simultaneous acquisition of brain activity signals from the sensorimotor area using NIRS combined with EEG, imagined hand clenching force and speed modulation of brain activity, as well as 6-class classification of these imagined motor parameters by NIRS-EEG were explored. Near infrared probes were aligned with C3 and C4, and EEG electrodes were placed midway between the NIRS probes. NIRS and EEG signals were acquired from six healthy subjects during six imagined hand clenching force and speed tasks involving the right hand. The results showed that NIRS combined with EEG is effective for simultaneously measuring brain activity of the sensorimotor area. The study also showed that in the duration of (0, 10) s for imagined force and speed of hand clenching, HbO first exhibited a negative variation trend, which was followed by a negative peak. After the negative peak, it exhibited a positive variation trend with a positive peak about 6-8 s after termination of imagined movement. During (-2, 1) s, the EEG may have indicated neural processing during the preparation, execution, and monitoring of a given imagined force and speed of hand clenching. The instantaneous phase, frequency, and amplitude feature of the EEG were calculated by Hilbert transform; HbO and the difference between HbO and Hb concentrations were extracted. The features of NIRS and EEG were combined to classify three levels of imagined force [at 20/50/80% MVGF (maximum voluntary grip force)] and speed (at 0.5/1/2 Hz) of hand clenching by SVM. The average classification accuracy of the NIRS-EEG fusion feature was 0.74 ± 0.02. These results may provide increased control commands of force and speed for a brain-controlled robot based on NIRS-EEG.

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

Normative data for hand grip strength and key pinch strength, stratified by age and gender for a multiethnic Asian population.

PubMed

Lam, Ngee Wei; Goh, Hui Ting; Kamaruzzaman, Shahrul Bahyah; Chin, Ai-Vyrn; Poi, Philip Jun Hua; Tan, Maw Pin

2016-10-01

Hand strength is a good indicator of physical fitness and frailty among the elderly. However, there are no published hand strength references for Malaysians aged > 65 years. This study aimed to establish normative data for hand grip strength (HGS) and key pinch strength (KPS) for Malaysians aged ≥ 60 years, and explore the relationship between hand strength and physical ability. Healthy participants aged ≥ 60 years with no neurological conditions were recruited from rural and urban locations in Malaysia. HGS and KPS were measured using hand grip and key pinch dynamometers. Basic demographic data, anthropometric measures, modified Barthel Index scores and results of the Functional Reach Test (FRT), Timed Up and Go (TUG) test and Jebsen-Taylor Hand Function Test (JTHFT) were recorded. 362 subjects aged 60-93 years were recruited. The men were significantly stronger than the women in both HGS and KPS (p < 0.001). The hand strength of the study cohort was lower than that of elderly Western populations. Significant correlations were observed between hand strength, and residential area (p < 0.001), FRT (r = 0.236, p = 0.028), TUG (r = -0.227, p = 0.009) and JTHFT (r = -0.927, p < 0.001). This study established reference ranges for the HGS and KPS of rural and urban elderly Malaysian subpopulations. These will aid the use of hand strength as a screening tool for frailty among elderly persons in Malaysia. Future studies are required to determine the modifiable factors for poor hand strength. Copyright: © Singapore Medical Association

Normative data for hand grip strength and key pinch strength, stratified by age and gender for a multiethnic Asian population

PubMed Central

Lam, Ngee Wei; Goh, Hui Ting; Kamaruzzaman, Shahrul Bahyah; Chin, Ai-Vyrn; Poi, Philip Jun Hua; Tan, Maw Pin

2016-01-01

INTRODUCTION Hand strength is a good indicator of physical fitness and frailty among the elderly. However, there are no published hand strength references for Malaysians aged > 65 years. This study aimed to establish normative data for hand grip strength (HGS) and key pinch strength (KPS) for Malaysians aged ≥ 60 years, and explore the relationship between hand strength and physical ability. METHODS Healthy participants aged ≥ 60 years with no neurological conditions were recruited from rural and urban locations in Malaysia. HGS and KPS were measured using hand grip and key pinch dynamometers. Basic demographic data, anthropometric measures, modified Barthel Index scores and results of the Functional Reach Test (FRT), Timed Up and Go (TUG) test and Jebsen-Taylor Hand Function Test (JTHFT) were recorded. RESULTS 362 subjects aged 60–93 years were recruited. The men were significantly stronger than the women in both HGS and KPS (p < 0.001). The hand strength of the study cohort was lower than that of elderly Western populations. Significant correlations were observed between hand strength, and residential area (p < 0.001), FRT (r = 0.236, p = 0.028), TUG (r = −0.227, p = 0.009) and JTHFT (r = −0.927, p < 0.001). CONCLUSION This study established reference ranges for the HGS and KPS of rural and urban elderly Malaysian subpopulations. These will aid the use of hand strength as a screening tool for frailty among elderly persons in Malaysia. Future studies are required to determine the modifiable factors for poor hand strength. PMID:26768064

Closed-loop control of grasping with a myoelectric hand prosthesis: which are the relevant feedback variables for force control?

PubMed

Ninu, Andrei; Dosen, Strahinja; Muceli, Silvia; Rattay, Frank; Dietl, Hans; Farina, Dario

2014-09-01

In closed-loop control of grasping by hand prostheses, the feedback information sent to the user is usually the actual controlled variable, i.e., the grasp force. Although this choice is intuitive and logical, the force production is only the last step in the process of grasping. Therefore, this study evaluated the performance in controlling grasp strength using a hand prosthesis operated through a complete grasping sequence while varying the feedback variables (e.g., closing velocity, grasping force), which were provided to the user visually or through vibrotactile stimulation. The experiments were conducted on 13 volunteers who controlled the Otto Bock Sensor Hand Speed prosthesis. Results showed that vibrotactile patterns were able to replace the visual feedback. Interestingly, the experiments demonstrated that direct force feedback was not essential for the control of grasping force. The subjects were indeed able to control the grip strength, predictively, by estimating the grasping force from the prosthesis velocity of closing. Therefore, grasping without explicit force feedback is not completely blind, contrary to what is usually assumed. In our study we analyzed grasping with a specific prosthetic device, but the outcomes are also applicable for other devices, with one or more degrees-of-freedom. The necessary condition is that the electromyography (EMG) signal directly and proportionally controls the velocity/grasp force of the hand, which is a common approach among EMG controlled prosthetic devices. The results provide important indications on the design of closed-loop EMG controlled prosthetic systems.

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.

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

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.

FORCE MULTIPLIER FOR USE WITH MASTER SLAVES

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

Miles, L.E.; Parsons, T.C.; Howe, P.W.

1961-06-01

A force multiplier was designed. This piece of equipment was made to increase the gripping force presently available in the Model 8 master slave. The force multiplier described incorporates a clamp which can be quickly attached to and detached from the master slave hand. (auth)

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

A biomechanical assessment of isometric handgrip force and fatigue at different anatomical positions.

PubMed

Alkurdi, Ziad D; Dweiri, Yazan M

2010-05-01

The present work examined the handgrip force at different anatomical positions for both hands. Anthropometrics, handgrip force, and fatigue were obtained from a representative sample of 20 males randomly selected from the German Jordanian University students. The hand dynamometer first was calibrated with respect to the volunteer's maximal grip strength, and he was then asked to squeeze maximally until the grip force decreased to 50% of its maximal due to fatigue; this test was performed for both hands at different anatomical positions with 2 min of rest for recovery of muscle function. The results showed differences in the handgrip force between subjects of the same anatomical positions and for the different anatomical positions, differences in the time for 50% of the force maximal for both right hand and left hand, higher time required to achieve 50% of maximal handgrip force for the nondominant hand, and maximal handgrip force was obtained when arm adduction with 90 degrees forward at the elbow joint. Recommendations for future work are to measure fatigue time at different percentages, 25%, 50%, 60%, and 75% of maximal force and to investigate the factors affecting handgrip force over a larger sample.

Grip Strength and Its Relationship to Police Recruit Task Performance and Injury Risk: A Retrospective Cohort Study

PubMed Central

Stierli, Michael; Hinton, Benjamin

2017-01-01

Suitable grip strength is a police occupational requirement. The aim of this study was to investigate the association between grip strength, task performance and injury risk in a police population. Retrospective data of police recruits (n = 169) who had undergone basic recruit training were provided, including handgrip strength results, occupational task performance measures (consisting of police task simulations [SIM], tactical options [TACOPS] and marksmanship assessments) and injury records. Left hand grip strength (41.91 ± 8.29 kg) measures showed a stronger correlation than right hand grip strength (42.15 ± 8.53 kg) with all outcome measures. Recruits whose grip strength scores were lower were significantly more susceptible to failing the TACOPS occupational task assessment than those with greater grip strength scores, with significant (p ≤ 0.003) weak to moderate, positive correlations found between grip strength and TACOPS performance. A significant (p < 0.0001) correlation was found between grip strength, most notably of the left hand, and marksmanship performance, with those performing better in marksmanship having higher grip strength. Left hand grip strength was significantly associated with injury risk (r = −0.181, p = 0.018) but right hand grip strength was not. A positive association exists between handgrip strength and police recruit task performance (notably TACOPS and marksmanship) with recruits who scored poorly on grip strength being at greatest risk of occupational assessment task failure. PMID:28825688

Grip Strength and Its Relationship to Police Recruit Task Performance and Injury Risk: A Retrospective Cohort Study.

PubMed

Orr, Robin; Pope, Rodney; Stierli, Michael; Hinton, Benjamin

2017-08-21

Suitable grip strength is a police occupational requirement. The aim of this study was to investigate the association between grip strength, task performance and injury risk in a police population. Retrospective data of police recruits (n = 169) who had undergone basic recruit training were provided, including handgrip strength results, occupational task performance measures (consisting of police task simulations [SIM], tactical options [TACOPS] and marksmanship assessments) and injury records. Left hand grip strength (41.91 ± 8.29 kg) measures showed a stronger correlation than right hand grip strength (42.15 ± 8.53 kg) with all outcome measures. Recruits whose grip strength scores were lower were significantly more susceptible to failing the TACOPS occupational task assessment than those with greater grip strength scores, with significant ( p ≤ 0.003) weak to moderate, positive correlations found between grip strength and TACOPS performance. A significant ( p < 0.0001) correlation was found between grip strength, most notably of the left hand, and marksmanship performance, with those performing better in marksmanship having higher grip strength. Left hand grip strength was significantly associated with injury risk ( r = -0.181, p = 0.018) but right hand grip strength was not. A positive association exists between handgrip strength and police recruit task performance (notably TACOPS and marksmanship) with recruits who scored poorly on grip strength being at greatest risk of occupational assessment task failure.

Corticospinal control of the thumb-index grip depends on precision of force control: a transcranial magnetic stimulation and functional magnetic resonance imagery study in humans.

PubMed

Bonnard, M; Galléa, C; De Graaf, J B; Pailhous, J

2007-02-01

The corticospinal system (CS) is well known to be of major importance for controlling the thumb-index grip, in particular for force grading. However, for a given force level, the way in which the involvement of this system could vary with increasing demands on precise force control is not well-known. Using transcranial magnetic stimulation and functional magnetic resonance imagery, the present experiments investigated whether increasing the precision demands while keeping the averaged force level similar during an isometric dynamic low-force control task, involving the thumb-index grip, does affect the corticospinal excitability to the thumb-index muscles and the activation of the motor cortices, primary and non-primary (supplementary motor area, dorsal and ventral premotor and in the contralateral area), at the origin of the CS. With transcranial magnetic stimulation, we showed that, when precision demands increased, the CS excitability increased to either the first dorsal interosseus or the opponens pollicis, and never to both, for similar ongoing electromyographic activation patterns of these muscles. With functional magnetic resonance imagery, we demonstrated that, for the same averaged force level, the amplitude of blood oxygen level-dependent signal increased in relation to the precision demands in the hand area of the contralateral primary motor cortex in the contralateral supplementary motor area, ventral and dorsal premotor area. Together these results show that, during the course of force generation, the CS integrates online top-down information to precisely fit the motor output to the task's constraints and that its multiple cortical origins are involved in this process, with the ventral premotor area appearing to have a special role.

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.

Exploratory study on the effects of a robotic hand rehabilitation device on changes in grip strength and brain activity after stroke.

PubMed

Pinter, Daniela; Pegritz, Sandra; Pargfrieder, Christa; Reiter, Gudrun; Wurm, Walter; Gattringer, Thomas; Linderl-Madrutter, Regina; Neuper, Claudia; Fazekas, Franz; Grieshofer, Peter; Enzinger, Christian

2013-01-01

The brain mechanisms underlying successful recovery of hand fuenction after stroke are still not fully understood, although functional MRI (fMRI) studies underline the importance of neuronal plasticity. We explored potential changes in brain activity in 7 patients with subacute to chronic stroke (69 ± 8 years) with moderate- to high-grade distal paresis of the upper limb (Motricity Index: 59.4) after standardized robotic finger-hand rehabilitation training, in addition to conventional rehabilitation therapy for 3 weeks. Behavioral and fMRI assessments were carried out before and after training to characterize changes in brain activity and behavior. The Motricity Index (pre: 59.4, post: 67.2, P < .05) and grip force (pre: 7.26, post: 11.87, P < .05) of the paretic hand increased significantly after rehabilitation. On fMRI, active movement of the affected (left) hand resulted in contralesional (ie, ipsilateral) activation of the primary sensorimotor cortex prior to rehabilitation. After rehabilitation, activation appeared "normalized," including the ipsilesional primary sensorimotor cortex and supplementary motor area (SMA). No changes and no abnormalities of activation maps were seen during movement of the unaffected hand. Subsequent region-of-interest analyses showed no significant ipsilesional activation increases after rehabilitation. Despite behavioral improvements, we failed to identify consistent patterns of functional reorganization in our sample. This warrants caution in the use of fMRI as a tool to explore neural plasticity in heterogeneous samples lacking sufficient statistical power.

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.

An Investigation of the Mechanics and Sticking Region of a One-Repetition Maximum Close-Grip Bench Press versus the Traditional Bench Press

PubMed Central

Lockie, Robert G.; Callaghan, Samuel J.; Moreno, Matthew R.; Risso, Fabrice G.; Liu, Tricia M.; Stage, Alyssa A.; Birmingham-Babauta, Samantha A.; Stokes, John J.; Giuliano, Dominic V.; Lazar, Adrina; Davis, DeShaun L.; Orjalo, Ashley J.

2017-01-01

The close-grip bench press (CGBP) is a variation of the traditional bench press (TBP) that uses a narrower grip (~95% of biacromial distance (BAD)) and has potential application for athletes performing explosive arm actions from positions where the hands are held close to the torso. Limited research has investigated CGBP mechanics compared to the TBP. Twenty-seven resistance-trained individuals completed a one-repetition maximum TBP and CGBP. The TBP was performed with the preferred grip; the CGBP with a grip width of 95% BAD. A linear position transducer measured lift distance and duration; peak and mean power, velocity, and force; distance and time when peak power occurred; and work. Pre-sticking region (PrSR), sticking region, and post-sticking region distance and duration for each lift was measured. A repeated measures ANOVA was used to derive differences between TBP and CGBP mechanics (p < 0.01); effect sizes (d) were also calculated. A greater load was lifted in the TBP, thus mean force was greater (d = 0.16–0.17). Peak power and velocity were higher in the CGBP, which had a longer PrSR distance (d = 0.49–1.32). The CGBP could emphasize power for athletes that initiate explosive upper-body actions with the hands positioned close to the torso.

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

The Effect of Isometric Massage on Global Grip Strength after Conservative Treatment of Distal Radial Fractures. Pilot Study.

PubMed

Ratajczak, Karina; Płomiński, Janusz

2015-01-01

The most common fracture of the distal end of the radius is Colles' fracture. Treatment modalities available for use in hand rehabilitation after injury include massage. The aim of this study was to evaluate the effect of isometric massage on the recovery of hand function in patients with Colles fractures. For this purpose, the strength of the finger flexors was assessed as an objective criterion for the evaluation of hand function. The study involved 40 patients, randomly divided into Group A of 20 patients and Group B of 20 patients. All patients received physical therapy and exercised individually with a physiotherapist. Isometric massage was additionally used in Group A. Global grip strength was assessed using a pneumatic force meter on the first and last day of therapy. Statistical analysis was performed using STATISTICA. Statistical significance was defined as a P value of less than 0.05. In both groups, global grip strength increased significantly after the therapy. There was no statistically significant difference between the groups. The men and women in both groups equally improved grip strength. A statistically significant difference was demonstrated between younger and older patients, with younger patients achieving greater gains in global grip strength in both groups. The incorporation of isometric massage in the rehabilitation plan of patients after a distal radial fracture did not significantly contribute to faster recovery of hand function or improve their quality of life.

Effect of Isometric Hand Grip Exercises on Blood Flow and Placement of IV Catheters for Administration of Chemotherapy.

PubMed

Ozkaraman, Ayse; Yesilbalkan, Öznur Usta

2016-04-01

Complications may occur in the subcutaneous or subdermal tissues during IV administration of chemotherapy related to blood flow and catheter placement. Daily isometric hand grip exercises were evaluated for their effect on blood flow in the vessels of the nondominant arm before placement of IV catheters and the success rate of IV catheter placement on the first attempt. The study focused on patients with non-Hodgkin lymphoma receiving the first and second cycles of chemotherapy. The intervention group performed daily isometric hand grip exercises before chemotherapy with peripheral catheter insertion. The control group performed routine activities only. Blood flow was measured by ultrasound in the brachial artery (BA) and brachial vein (BV) of the nondominant arm before the first (T1) and second (T2) cycles of chemotherapy. Blood flow slightly increased in the intervention group at T2 compared to T1. In the control group, blood flow decreased in the BA and did not change in the BV at T2 compared to T1. The success rate for first-attempt placement of a peripheral IV catheter was the same for the intervention and control groups.

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.

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.

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.

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…

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.

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.

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.

Effects of hand configuration on muscle force coordination, co-contraction and concomitant intermuscular coupling during maximal isometric flexion of the fingers.

PubMed

Charissou, Camille; Amarantini, David; Baurès, Robin; Berton, Eric; Vigouroux, Laurent

2017-11-01

The mechanisms governing the control of musculoskeletal redundancy remain to be fully understood. The hand is highly redundant, and shows different functional role of extensors according to its configuration for a same functional task of finger flexion. Through intermuscular coherence analysis combined with hand musculoskeletal modelling during maximal isometric hand contractions, our aim was to better understand the neural mechanisms underlying the control of muscle force coordination and agonist-antagonist co-contraction. Thirteen participants performed maximal isometric flexions of the fingers in two configurations: power grip (Power) and finger-pressing on a surface (Press). Hand kinematics and force/moment measurements were used as inputs in a musculoskeletal model of the hand to determine muscular tensions and co-contraction. EMG-EMG coherence analysis was performed between wrist and finger flexors and extensor muscle pairs in alpha, beta and gamma frequency bands. Concomitantly with tailored muscle force coordination and increased co-contraction between Press and Power (mean difference: 48.08%; p < 0.05), our results showed muscle-pair-specific modulation of intermuscular coupling, characterized by pair-specific modulation of EMG-EMG coherence between Power and Press (p < 0.05), and a negative linear association between co-contraction and intermuscular coupling for the ECR/FCR agonist-antagonist muscle pair (r = - 0.65; p < 0.05). This study brings new evidence that pair-specific modulation of EMG-EMG coherence is related to modulation of muscle force coordination during hand contractions. Our results highlight the functional importance of intermuscular coupling as a mechanism contributing to the control of muscle force synergies and agonist-antagonist co-contraction.

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.

Force reflecting hand controller for manipulator teleoperation

NASA Technical Reports Server (NTRS)

Bryfogle, Mark D.

1991-01-01

A force reflecting hand controller based upon a six degree of freedom fully parallel mechanism, often termed a Stewart Platform, has been designed, constructed, and tested as an integrated system with a slave robot manipulator test bed. A force reflecting hand controller comprises a kinesthetic device capable of transmitting position and orientation commands to a slave robot manipulator while simultaneously representing the environmental interaction forces of the slave manipulator back to the operator through actuators driving the hand controller mechanism. The Stewart Platform was chosen as a novel approach to improve force reflecting teleoperation because of its inherently high ratio of load generation capability to system mass content and the correspondingly high dynamic bandwidth. An additional novelty of the program was to implement closed loop force and torque control about the hand controller mechanism by equipping the handgrip with a six degree of freedom force and torque measuring cell. The mechanical, electrical, computer, and control systems are discussed and system tests are presented.

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.

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.

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.

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.

Bimanual Force Variability and Chronic Stroke: Asymmetrical Hand Control

PubMed Central

Kang, Nyeonju; Cauraugh, James H.

2014-01-01

The purpose of this study was to investigate force variability generated by both the paretic and non-paretic hands during bimanual force control. Nine chronic stroke individuals and nine age-matched individuals with no stroke history performed a force control task with both hands simultaneously. The task involved extending the wrist and fingers at 5%, 25%, and 50% of maximum voluntary contraction. Bimanual and unimanual force variability during bimanual force control was determined by calculating the coefficient of variation. Analyses revealed two main findings: (a) greater bimanual force variability in the stroke group than the control group and (b) increased force variability by the paretic hands during bimanual force control in comparison to the non-paretic hands at the 5% and 25% force production conditions. A primary conclusion is that post stroke bimanual force variability is asymmetrical between hands. PMID:25000185

Motor Unit Number Estimate and Isometric Hand Grip Strength in Military Veterans with or Without Muscular Complaints: Reference Values for Longitudinal Follow-up.

PubMed

Li, Mian; Yao, Wenguo; Sundahl, Cynthia

2018-03-26

It remains unclear if Gulf War (GW) veterans have a higher risk of developing motor neuron disorder. We intended to establish baseline neurophysiological values, including thenar motor unit number estimate (MUNE) and isometric hand grip (IHG) strength, to compare future follow-ups of deployed GW veterans with or without muscular complaints. We evaluated 19 GW veterans with self-reported weakness, cramps, or excessive muscle fatigue (Ill-19) and compared them with 18 controls without such muscular complaints (C-18). We performed MUNE on hand thenar muscles using adapted multipoint stimulation method for Ill-19 and 15 controls (C-15). We measured IHG strength (maximum force, endurance, and fatigue level) on Ill-19 and C-18 with a hand dynamometer. We performed nerve conduction studies on all study participants to determine which subjects had mild carpal tunnel syndrome (CTS). We compared the MUNE and IHG strength measures between Ill group and controls and between those with CTS and those without CTS. We obtained thenar MUNE of Ill-19 (95% CI of mean: 143-215; mean age: 46 yr) and compared it with that of C-15 (95% CI of mean: 161-230; mean age: 45 yr), and 95% of CI of mean among IHG strength variables (maximum force: 324-381 Newton; endurance: 32-42 s; fatigue level: 24%-33%) compared with C-18 (maximum force: 349-408 Newton; endurance: 35-46 s; fatigue level: 21%-27%). There was no significant difference in either MUNE or IHG strength between Ill-19 group and controls. The MUNE and IHG maximum forces were significantly lower in those with CTS compared with those without CTS. As a surrogate of mild CTS, the median versus ulnar distal sensory latency on nerve conduction study was only weakly associated with MUNE, maximum force, and fatigue level, respectively. To our knowledge, no published study on MUNE reference values of military veteran population has been available. The quantifiable values of both thenar MUNE and IHG strength of military veterans serve as

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.

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

Cortical and reticular contributions to human precision and power grip.

PubMed

Tazoe, Toshiki; Perez, Monica A

2017-04-15

The corticospinal tract contributes to the control of finger muscles during precision and power grip. We explored the neural mechanisms contributing to changes in corticospinal excitability during these gripping configurations. Motor evoked potentials (MEPs) elicited by cortical, but not by subcortical, stimulation were more suppressed during power grip compared with precision grip and index finger abduction. Intracortical inhibition was more reduced during power grip compared with the other tasks. An acoustic startle cue, a stimulus that engages the reticular system, suppressed MEP size during power grip to a lesser extent than during the other tasks at a cortical level and this positively correlated with changes in intracortical inhibition. Our findings suggest that changes in corticospinal excitability during gross more than fine finger manipulations are largely cortical in origin and that the reticular system contributed, at least in part, to these effects. It is well accepted that the corticospinal tract contributes to the control of finger muscles during precision and power grip in humans but the neural mechanisms involved remain poorly understood. Here, we examined motor evoked potentials elicited by cortical and subcortical stimulation of corticospinal axons (MEPs and CMEPs, respectively) and the activity in intracortical circuits (suppression of voluntary electromyography) and spinal motoneurons (F-waves) in an intrinsic hand muscle during index finger abduction, precision grip and power grip. We found that the size of MEPs, but not CMEPs, was more suppressed during power grip compared with precision grip and index finger abduction, suggesting a cortical origin for these effects. Notably, intracortical inhibition was more reduced during power grip compared with the other tasks. To further examine the origin of changes in intracortical inhibition we assessed the contribution of the reticular system, which projects to cortical neurons, and projects to spinal

EMG activity of finger flexor muscles and grip force following low-dose transcutaneous electrical nerve stimulation in healthy adult subjects.

PubMed

Kafri, Michal; Zaltsberg, Nir; Dickstein, Ruth

2015-01-01

Somatosensory stimulation modulates cortical and corticospinal excitability and consequently affects motor output. Therefore, low-amplitude transcutaneous electrical nerve stimulation (TENS) has the potential to elicit favorable motor responses. The purpose of the two presented pilot studies was to shed light on TENS parameters that are relevant for the enhancement of two desirable motor outcomes, namely, electromyographic (EMG) activity and contraction strength of the finger flexors and wrist muscles. In 5 and 10 healthy young adults (in Study I and Study II, respectively) TENS was delivered to the volar aspect of the forearm. We manipulated TENS frequency (150 Hz vs. 5 Hz), length of application (10, 20, and 60 min), and side of application (unilateral, right forearm vs. bilateral forearms). EMG amplitude and grip force were measured before (Pre), immediately after (Post), and following 15 min of no stimulation (Study I only). The results indicated that low-frequency bursts of TENS applied to the skin overlying the finger flexor muscles enhance the EMG activity of the finger flexors and grip force. The increase in EMG activity of the flexor muscles was observed after 20 min of stimulation, while grip force was increased only after 1 h. The effects of uni- and bilateral TENS were comparable. These observations allude to a modulatory effect of TENS on the tested motor responses; however, unequivocal conclusions of the findings are hampered by individual differences that affect motor outcomes, such as in level of attention.

Biodynamic response at the palm of the human hand subjected to a random vibration.

PubMed

Dong, Ren G; McDowell, Thomas W; Welcome, Daniel E

2005-01-01

This study investigated the biodynamic response (BR) distributed at the palm of the hand subjected to a random vibration. Twelve male subjects were used in the experiment. Each subject applied three coupling actions (grip-only, push-only, and combined grip and push) on a simulated tool handle at three different levels (50, 75, and 100 N) of palm force. This study found that the hand-arm system resonated mostly in the frequency range of 20 to 50 Hz, depending on the specific test treatment and individual characteristics. The maximum vibration power transmission through the palm occurred at the resonant frequency. Increasing the effective palm force generally increased the BR magnitude and resonant frequency. The apparent stiffness measured at the middle frequencies (80-100 Hz) is correlated to the BR in almost the entire frequency range (20-1,000 Hz). Under the same palm force, the push-only action corresponded to the highest BR values while the grip-only action generally produced the lowest values. Since the resonant frequency range matches the dominant vibration frequency range of many percussive tools, it is anticipated that the palm BR and vibration power transmission may have an association with vibration-induced injuries or disorders in the wrist-arm system among the workers using these tools.

Multidigit force control during unconstrained grasping in response to object perturbations

PubMed Central

Haschke, Robert; Ritter, Helge; Santello, Marco; Ernst, Marc O.

2017-01-01

Because of the complex anatomy of the human hand, in the absence of external constraints, a large number of postures and force combinations can be used to attain a stable grasp. Motor synergies provide a viable strategy to solve this problem of motor redundancy. In this study, we exploited the technical advantages of an innovative sensorized object to study unconstrained hand grasping within the theoretical framework of motor synergies. Participants were required to grasp, lift, and hold the sensorized object. During the holding phase, we repetitively applied external disturbance forces and torques and recorded the spatiotemporal distribution of grip forces produced by each digit. We found that the time to reach the maximum grip force during each perturbation was roughly equal across fingers, consistent with a synchronous, synergistic stiffening across digits. We further evaluated this hypothesis by comparing the force distribution of human grasping vs. robotic grasping, where the control strategy was set by the experimenter. We controlled the global hand stiffness of the robotic hand and found that this control algorithm produced a force pattern qualitatively similar to human grasping performance. Our results suggest that the nervous system uses a default whole hand synergistic control to maintain a stable grasp regardless of the number of digits involved in the task, their position on the objects, and the type and frequency of external perturbations. NEW & NOTEWORTHY We studied hand grasping using a sensorized object allowing unconstrained finger placement. During object perturbation, the time to reach the peak force was roughly equal across fingers, consistently with a synergistic stiffening across fingers. Force distribution of a robotic grasping hand, where the control algorithm is based on global hand stiffness, was qualitatively similar to human grasping. This suggests that the central nervous system uses a default whole hand synergistic control to maintain

Initial development of a device for controlling manually applied forces.

PubMed

Waddington, Gordon S; Adams, Roger D

2007-05-01

In both simulation and manual therapy studies, substantial variability has been shown when therapists attempt to replicate an applied force. Knowledge about the forces employed during treatment could reduce this variability. In the current project, a prototype for a mobilizing device incorporating a dynamometer was constructed. The prototype device was built around a conventional "hand-grip" dynamometer to give dial visibility during application of mobilizing forces and a moulded handle was used to increase the hand contact surface during force application. The variability of the mobilization forces produced was measured, and ratings of comfort during a simulated spinal mobilization technique were obtained from therapists. Thirty physiotherapists were randomly allocated to apply either: (i) their own estimate of a grade III mobilization force using their hands in a pisiform grip or (ii) a 100N force with the manual therapy dynamometer, and to rate comfort during the performance of both techniques on a 100mm visual analogue scale. Variance in dynamometer-dial-guided force application was always significantly less than the variance in therapist-concept-guided force application. Repeated-measures tests showed that the mean force produced at grade III was not significantly different from 100N, but physiotherapist comfort ratings were found to be significantly greater (P<0.01) when the manual therapy dynamometer was used. Manually applied force variability was significantly less and therapist comfort greater when using a device with visual access to a dial giving immediate force readout.

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.

Nut-cracking behaviour in wild-born, rehabilitated bonobos (Pan paniscus): a comprehensive study of hand-preference, hand grips and efficiency.

PubMed

Neufuss, Johanna; Humle, Tatyana; Cremaschi, Andrea; Kivell, Tracy L

2017-02-01

There has been an enduring interest in primate tool-use and manipulative abilities, most often with the goal of providing insight into the evolution of human manual dexterity, right-hand preference, and what behaviours make humans unique. Chimpanzees (Pan troglodytes) are arguably the most well-studied tool-users amongst non-human primates, and are particularly well-known for their complex nut-cracking behaviour, which has been documented in several West African populations. However, their sister-taxon, the bonobos (Pan paniscus), rarely engage in even simple tool-use and are not known to nut-crack in the wild. Only a few studies have reported tool-use in captive bonobos, including their ability to crack nuts, but details of this complex tool-use behaviour have not been documented before. Here, we fill this gap with the first comprehensive analysis of bonobo nut-cracking in a natural environment at the Lola ya Bonobo sanctuary, Democratic Republic of the Congo. Eighteen bonobos were studied as they cracked oil palm nuts using stone hammers. Individual bonobos showed exclusive laterality for using the hammerstone and there was a significant group-level right-hand bias. The study revealed 15 hand grips for holding differently sized and weighted hammerstones, 10 of which had not been previously described in the literature. Our findings also demonstrated that bonobos select the most effective hammerstones when nut-cracking. Bonobos are efficient nut-crackers and not that different from the renowned nut-cracking chimpanzees of Bossou, Guinea, which also crack oil palm nuts using stones. © 2016 Wiley Periodicals, Inc.

Force Model for Control of Tendon Driven Hands

NASA Technical Reports Server (NTRS)

Pena, Edward; Thompson, David E.

1997-01-01

Knowing the tendon forces generated for a given task such as grasping via a model, an artificial hand can be controlled. A two-dimensional force model for the index finger was developed. This system is assumed to be in static equilibrium, therefore, the equations of equilibrium were applied at each joint. Constraint equations describing the tendon branch connectivity were used. Gaussian elimination was used to solve for the unknowns of the Linear system. Results from initial work on estimating tendon forces in post-operative hands during active motion therapy were discussed. The results are important for understanding the effects of hand position on tendon tension, elastic effects on tendon tension, and overall functional anatomy of the hand.

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.

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.

Increased Force Variability in Chronic Stroke: Contributions of Force Modulation below 1 Hz

PubMed Central

Lodha, Neha; Misra, Gaurav; Coombes, Stephen A.; Christou, Evangelos A.; Cauraugh, James H.

2013-01-01

Increased force variability constitutes a hallmark of arm disabilities following stroke. Force variability is related to the modulation of force below 1 Hz in healthy young and older adults. However, whether the increased force variability observed post stroke is related to the modulation of force below 1 Hz remains unknown. Thus, the purpose of this study was to compare force modulation below 1 Hz in chronic stroke and age-matched healthy individuals. Both stroke and control individuals (N = 26) performed an isometric grip task to submaximal force levels. Coefficient of variation quantified force variability, and power spectrum density of force quantified force modulation below 1 Hz with a high resolution (0.07 Hz). Analyses indicated that force variability was greater for the stroke group compared with to healthy controls and for the paretic hand compared with the non-paretic hand. Force modulation below 1 Hz differentiated the stroke individuals and healthy controls, as well as the paretic and non-paretic hands. Specifically, stroke individuals (paretic hand) exhibited greater power ∼0.2 Hz (0.07–0.35 Hz) and lesser power ∼0.6 Hz (0.49–0.77 Hz) compared to healthy controls (non-dominant hand). Similarly, the paretic hand exhibited greater power ∼0.2 Hz, and lesser power ∼0.6 Hz than the non-paretic hand. Moreover, variability of force was strongly predicted from the modulation of specific frequencies below 1 Hz (R 2 = 0.80). Together, these findings indicate that the modulation of force below 1 Hz provides significant insight into changes in motor control after stroke. PMID:24386208

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.

Hand Rehabilitation Learning System With an Exoskeleton Robotic Glove.

PubMed

Ma, Zhou; Ben-Tzvi, Pinhas; Danoff, Jerome

2016-12-01

This paper presents a hand rehabilitation learning system, the SAFE Glove, a device that can be utilized to enhance the rehabilitation of subjects with disabilities. This system is able to learn fingertip motion and force for grasping different objects and then record and analyze the common movements of hand function including grip and release patterns. The glove is then able to reproduce these movement patterns in playback fashion to assist a weakened hand to accomplish these movements, or to modulate the assistive level based on the user's or therapist's intent for the purpose of hand rehabilitation therapy. Preliminary data have been collected from healthy hands. To demonstrate the glove's ability to manipulate the hand, the glove has been fitted on a wooden hand and the grasping of various objects was performed. To further prove that hands can be safely driven by this haptic mechanism, force sensor readings placed between each finger and the mechanism are plotted. These experimental results demonstrate the potential of the proposed system in rehabilitation therapy.

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.

Are they half as strong as they used to be? An experiment testing whether age-related social comparisons impair older people's hand grip strength and persistence

PubMed Central

Swift, Hannah J; Lamont, Ruth A

2012-01-01

Objective To assess how age-related social comparisons, which are likely to arise inadvertently or deliberately during assessments, may affect older people's performance on tests that are used to assess their needs and capability. Design The study randomly assigned participants to a comparison with younger people or a no comparison condition and assessed hand grip strength and persistence. Gender, education, type of residence, arthritis and age were also recorded. Setting Age UK centres and senior's lunches in the South of England. Participants An opportunity sample of 56 adults, with a mean age of 82.25 years. Main outcomes measures Hand grip strength measured using a manual hand dynamometer and persistence of grip measured using a stopwatch. Results Comparison caused significantly worse performance measured by both strength (comparison =6.85 kg, 95% CI 4.19 kg to 9.5 kg, control group =11.07 kg, 95% CI 8.47 kg to 13.68 kg, OR =0.51, p=0.027) and persistence (comparison =8.36 s, 95% CI 5.44 s to 11.29 s; control group =12.57 s, 95% CI 9.7 s to 15.45 s, OR =0.49, p=0.045). These effects remained significant after accounting for differences in arthritis, gender, education and adjusting for population age norms. Conclusions Due to the potential for age comparisons and negative stereotype activation during assessment of older people, such assessments may underestimate physical capability by up to 50%. Because age comparisons are endemic, this means that assessment tests may sometimes seriously underestimate older people's capacity and prognosis, which has implications for the way healthcare professionals treat them in terms of autonomy and dependency. PMID:22619267

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

Effects of Computer-Aided Interlimb Force Coupling Training on Paretic Hand and Arm Motor Control following Chronic Stroke: A Randomized Controlled Trial

PubMed Central

Lin, Chueh-Ho; Chou, Li-Wei; Luo, Hong-Ji; Tsai, Po-Yi; Lieu, Fu-Kong; Chiang, Shang-Lin; Sung, Wen-Hsu

2015-01-01

Objective We investigated the training effects of interlimb force coupling training on paretic upper extremity outcomes in patients with chronic stroke and analyzed the relationship between motor recovery of the paretic hand, arm and functional performances on paretic upper limb. Design A randomized controlled trial with outcome assessment at baseline and after 4 weeks of intervention. Setting Taipei Veterans General Hospital, National Yang-Ming University. Participants Thirty-three subjects with chronic stroke were recruited and randomly assigned to training (n = 16) and control groups (n = 17). Interventions The computer-aided interlimb force coupling training task with visual feedback included different grip force generation methods on both hands. Main Outcome Measures The Barthel Index (BI), the upper extremity motor control Fugl-Meyer Assessment (FMA-UE), the Motor Assessment Score (MAS), and the Wolf Motor Function Test (WMFT). All assessments were executed by a blinded evaluator, and data management and statistical analysis were also conducted by a blinded researcher. Results The training group demonstrated greater improvement on the FMA-UE (p<.001), WMFT (p<.001), MAS (p = .004) and BI (p = .037) than the control group after 4 weeks of intervention. In addition, a moderate correlation was found between the improvement of scores for hand scales of the FMA and other portions of the FMA UE (r = .528, p = .018) or MAS (r = .596, p = .015) in the training group. Conclusion Computer-aided interlimb force coupling training improves the motor recovery of a paretic hand, and facilitates motor control and enhances functional performance in the paretic upper extremity of people with chronic stroke. Trial Registration ClinicalTrials.gov NCT02247674. PMID:26193492

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.

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

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

Metal muscles and nerves—a self-sensing SMA-actuated hand concept

NASA Astrophysics Data System (ADS)

Simone, F.; Rizzello, G.; Seelecke, S.

2017-09-01

Bio-inspired hand-like grippers actuated by Shape Memory Alloy (SMA) wires represent an emerging new technology with potential applications in many different fields, ranging from industrial assembly processes to biomedical systems. The inherently high energy density makes SMAs a natural choice for compact, lightweight, and silent actuator systems capable of producing a high amount of work, such as hand prostheses or robotic systems in industrial human/machine environments. In this work, a concept for a compact and versatile gripping system is developed, in which SMA wires are implemented as antagonistic muscles actuating an artificial hand with three fingers. In order to combine high gripping force with sufficient actuation speed, the muscle implementation pursues a multi-wire concept with several 0.1 mm diameter NiTi wires connected in parallel, in order to increase the surface-to-volume ratio for accelerated cooling. The paper starts with an illustration of the design concept of an individual 3-phalanx-finger, along with kinematic considerations for optimal placement of SMA wires. Three identical fingers are subsequently fabricated via 3D printing and assembled into a hand-like gripper. The maximum displacement of each finger phalanx is measured, and an average phalanxes dynamic responsiveness is evaluated. SMA self-sensing is documented by experiments relating the wires change in resistance to the finger motion. Several finger force measurements are also performed. The versatility of the gripper is finally documented by displaying a variety of achievable grasping configurations.

Sweating responses to isometric hand-grip exercise and forearm muscle metaboreflex in prepubertal children and elderly.

PubMed

Amano, Tatsuro; Kai, Seiko; Nakajima, Michi; Ichinose-Kuwahara, Tomoko; Gerrett, Nicola; Kondo, Narihiko; Inoue, Yoshimitsu

2017-02-01

What is the central question of this study? Non-thermal factors (e.g. muscle metaboreflex) contribute to the sweating response during exercise. Although it is well recognized that the sweating responses caused by core temperature elevation in prepubertal children and the elderly are attenuated compared with young adults, it is unknown whether non-thermal sweating is also attenuated in these populations. What is the main finding and its importance? The non-thermal sweating response during isometric hand-grip exercise and isolated muscle metaboreflex were attenuated in prepubertal children compared with young adults in a non-uniform manner over the body, but only during the muscle metaboreflex in the elderly. This may explain the maturation- and ageing-related decline of sweating during exercise. The purpose of the present study was to investigate sweating responses to isometric hand-grip (IH) exercise and muscle metaboreflex in prepubertal children and the elderly. In hot conditions (ambient temperature, 35°C; relative humidity, 45%), 13 healthy young adults, 10 prepubertal children and 10 elderly subjects (aged 20.4 ± 1.2, 11.4 ± 0.5 and 63.5 ± 3.1 years, respectively) repeated a three hand-grip exercise protocol that consisted of 1 min IH exercise at 15, 30 or 45% of maximal voluntary contraction (MVC) followed by 2 min postexercise forearm occlusion. Local sweat rates (SRs) on the forehead, chest, forearm, thigh and palm were continuously measured (ventilated capsule method). The forehead SR in prepubertal children during IH exercise at 45% MVC was significantly lower than that of young adults (0.26 ± 0.22 and 0.08 ± 0.15 mg cm -2  min -1 for young adults and children, respectively; P < 0.05) but not of the elderly at any exercise intensities. The SR on the chest (0.22 ± 0.22 and -0.01 ± 0.05 mg cm -2  min -1 for young adults and children, respectively), forearm (0.14 ± 0.12 and 0.03 ± 0.04 mg cm -2  min -1 ) and thigh (0

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.

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.

The effect of bracing availability on one-hand isometric force exertion capability.

PubMed

Jones, Monica L H; Reed, Matthew P; Chaffin, Don B

2013-01-01

Environmental obstructions that workers encounter can kinematically limit the postures that they can achieve. However, such obstructions can also provide an opportunity for additional support by bracing with the hand, thigh or other body part. The reaction forces on bracing surfaces, which are in addition to those acting at the feet and task hand, are hypothesised to improve force exertion capability, and become required inputs to biomechanical analysis of tasks with bracing. The effects of kinematic constraints and associated bracing opportunities on isometric hand force were quantified in a laboratory study of 22 men and women. Analyses of one-hand maximal push, pull and lift tasks demonstrated that bracing surfaces available at the thighs and non-task hand enabled participants to exert an average of 43% more force at the task hand. Task hand force direction deviated significantly from the nominal direction for exertions performed with bracing at both medium and low task hand locations. This study quantifies the effect of bracing on kinematically constrained force exertions. Knowledge that appropriate bracing surfaces can substantially increase hand force is critical to the evaluation of task-oriented strength capability. Force estimates may also involve large off-axis components, which have clear implications for ergonomic analyses of manual tasks.

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

Foot forces induced through Tai Chi push-hand exercises.

PubMed

Wong, Shiu Hong; Ji, Tianjian; Hong, Youlian; Fok, Siu Lun; Wang, Lin

2013-08-01

The low impact forces of Tai Chi push-hand exercises may be particularly suited for older people and for those with arthritis; however, the biomechanics of push-hand exercises have not previously been reported. This paper examines the ground reaction forces (GRFs) and plantar force distributions during Tai Chi push-hand exercises in a stationary stance with and without an opponent. Ten male Tai Chi practitioners participated in the study. The GRFs of each foot were measured in three perpendicular directions using two force plates (Kistler). The plantar force distribution of each foot was measured concurrently using an insole sensor system (Novel). The results showed that the average maximum vertical GRF of each foot was not more than 88% ± 6.1% of the body weight and the sum of the vertical forces (103% ± 1.4%) generated by the two feet approximately equals the body weight at any one time. The horizontal GRFs generated by the two feet were in the opposite directions and the measured mean peak values were not more than 12% ± 2.8% and 17% ± 4.3% of the body weight in the medio-lateral and antero-posterior directions respectively. Among the nine plantar areas, the toes sustained the greatest plantar force. This study indicates that push-hand exercises generate lower vertical forces than those induced by walking, bouncing, jumping and Tai Chi gait, and that the greatest plantar force is located in the toe area, which may have an important application in balance training particularly for older adults.

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.

Assessment of coarse and fine hand motor performance in asymptomatic subjects exposed to hand-arm vibration.

PubMed

Popević, Martin B; Janković, Srđan M; Borjanović, Srđan S; Jovičić, Slavica R; Tenjović, Lazar R; Milovanović, Aleksandar P S; Bulat, Petar

2014-03-01

A frequently encountered exposure profile for hand-arm vibration in contemporary occupational setting comprises workers with a long history of intermittent exposure but without detectable signs of hand-arm vibration syndrome (HAVS). Yet, most of the published studies deal with developed HAVS cases, rarely discussing the biological processes that may be involved in degradation of manual dexterity and grip strength when it can be most beneficial - during the asymptomatic stage. In the present paper, a group of 31 male asymptomatic vibration-exposed workers (according to the Stockholm Workshop Scale) were compared against 30 male controls. They were tested using dynamometry and dexterimetry (modelling coarse and fine manual performance respectively) and cold provocation was done to detect possible differences in manual performance drop on these tests. The results showed reduced manual dexterity but no significant degradation in hand grip strength in the exposed subjects. This suggests that intermittent exposure profile and small cumulative vibration dose could only lead to a measurable deficit in manual dexterity but not hand grip strength even at non-negligible A(8) levels and long term exposures.

Hand digit control in children: motor overflow in multi-finger pressing force vector space during maximum voluntary force production.

PubMed

Shim, Jae Kun; Karol, Sohit; Hsu, Jeffrey; de Oliveira, Marcio Alves

2008-04-01

The aim of this study was to investigate the contralateral motor overflow in children during single-finger and multi-finger maximum force production tasks. Forty-five right handed children, 5-11 years of age produced maximum isometric pressing force in flexion or extension with single fingers or all four fingers of their right hand. The forces produced by individual fingers of the right and left hands were recorded and analyzed in four-dimensional finger force vector space. The results showed that increases in task (right) hand finger forces were linearly associated with non-task (left) hand finger forces. The ratio of the non-task hand finger force magnitude to the corresponding task hand finger force magnitude, termed motor overflow magnitude (MOM), was greater in extension than flexion. The index finger flexion task showed the smallest MOM values. The similarity between the directions of task hand and non-task hand finger force vectors in four-dimensional finger force vector space, termed motor overflow direction (MOD), was the greatest for index and smallest for little finger tasks. MOM of a four-finger task was greater than the sum of MOMs of single-finger tasks, and this phenomenon was termed motor overflow surplus. Contrary to previous studies, no single-finger or four-finger tasks showed significant changes of MOM or MOD with the age of children. We conclude that the contralateral motor overflow in children during finger maximum force production tasks is dependent upon the task fingers and the magnitude and direction of task finger forces.

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

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.

Hand function in workers with hand-arm vibration syndrome.

PubMed

Cederlund, R; Isacsson, A; Lundborg, G

1999-01-01

Hand-arm vibration syndrome has been specially addressed in the Scandinavian countries in recent years, but the syndrome is still not sufficiently recognized in many countries. The object of this preliminary study was to describe the nature and character of vibration-induced impairment in the hands of exposed workers. Twenty symptomatic male workers (aged 28 to 65 years) subjected to vibration by hand-held tools were interviewed about subjective symptoms and activities of daily living and were assessed with a battery of objective tests for sensibility, dexterity, grip function, and grip strength. The test results were compared with normative data. The majority of patients complained of cold intolerance, numbness, pain, sensory impairment, and difficulties in handling manual tools and in handwriting. The various objective tests showed considerable variation in indications of pathologic outcome, revealing differences in sensitivity to detect impaired hand function. Semmes-Weinstein monofilament testing for perception of light touch-deep pressure sensation, the small-object shape identification test, and moving two-point discrimination testing for functional sensibility provided the most indications of pathologic outcomes. The authors conclude that vibration-exposed patients present considerable impairment in hand function.

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.

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.

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.

Clinical disorders and pressure-pain threshold of the forearm and hand among automobile assembly line workers.

PubMed

Byström, S; Hall, C; Welander, T; Kilbom, A

1995-12-01

The prevalence of forearm and hand disorders was examined by questionnaire and clinical examination in 199 automobile assembly line workers and in 186 controls. The pressure-pain threshold, hand grip force and hand anthropometry were also studied. There was an increased prevalence of de Quervain's disease for male automobile assembly line workers, and of carpal tunnel syndrome in female workers. The prevalence of symptoms in the forearm and hand during the last 7 days were twice as high among automobile assembly line workers than controls for both men and women. The occurrence of symptoms in the last 7 days was associated with de Quervain's disease, carpal tunnel syndrome and sick-leave due to forearm or hand problems, and it also influenced activities of daily living. Hand grip strength and anthropometrics were not associated with findings in the clinical examination or the occurrence of symptoms in the last 7 days. Low pressure-pain threshold was not associated with findings in the clinical examination, except for reported occurrence of symptoms in the last 7 days for women. Pressure-pain threshold as an indicator of tissue damage is discussed.

Get a Grip! A Middle School Engineering Challenge

ERIC Educational Resources Information Center

Olds, Suzanne A.; Harrell, Deborah A.; Valente, Michael E.

2006-01-01

Investigating the field of engineering offers the opportunity for interdisciplinary, hands-on, inquiry-based units that integrate real-world applications. However, many K-12 students are not exposed to engineering until they enter college. Get a Grip! is a problem-based unit that places middle school students in the role of engineers who are…

Grip and slip of L1-CAM on adhesive substrates direct growth cone haptotaxis

PubMed Central

Abe, Kouki; Katsuno, Hiroko; Toriyama, Michinori; Baba, Kentarou; Mori, Tomoyuki; Hakoshima, Toshio; Kanemura, Yonehiro; Watanabe, Rikiya; Inagaki, Naoyuki

2018-01-01

Chemical cues presented on the adhesive substrate direct cell migration, a process termed haptotaxis. To migrate, cells must generate traction forces upon the substrate. However, how cells probe substrate-bound cues and generate directional forces for migration remains unclear. Here, we show that the cell adhesion molecule (CAM) L1-CAM is involved in laminin-induced haptotaxis of axonal growth cones. L1-CAM underwent grip and slip on the substrate. The ratio of the grip state was higher on laminin than on the control substrate polylysine; this was accompanied by an increase in the traction force upon laminin. Our data suggest that the directional force for laminin-induced growth cone haptotaxis is generated by the grip and slip of L1-CAM on the substrates, which occur asymmetrically under the growth cone. This mechanism is distinct from the conventional cell signaling models for directional cell migration. We further show that this mechanism is disrupted in a human patient with L1-CAM syndrome, suffering corpus callosum agenesis and corticospinal tract hypoplasia. PMID:29483251

A Low-Cost Hand Trainer Device Based On Microcontroller Platform

NASA Astrophysics Data System (ADS)

Sabor, Muhammad Akmal Mohammad; Thamrin, Norashikin M.

2018-03-01

Conventionally, the rehabilitation equipment used in the hospital or recovery center to treat and train the muscle of the stroke patient is implementing the pneumatic or compressed air machine. The main problem caused by this equipment is that the arrangement of the machine is quite complex and the position of it has been locked and fixed, which can cause uncomfortable feeling to the patients throughout the recovery session. Furthermore, the harsh movement from the machine could harm the patient as it does not allow flexibility movement and the use of pneumatic actuator has increased the gripping force towards the patient which could hurt them. Therefore, the main aim of this paper is to propose the development of the Bionic Hand Trainer based on Arduino platform, for a low-cost solution for rehabilitation machine as well as allows flexibility and smooth hand movement for the patients during the healing process. The scope of this work is to replicate the structure of the hand only at the fingers structure that is the phalanges part, which inclusive the proximal, intermediate and distal of the fingers. In order to do this, a hand glove is designed by equipping with flex sensors at every finger and connected them to the Arduino platform. The movement of the hand will motorize the movement of the dummy hand that has been controlled by the servo motors, which have been equipped along the phalanges part. As a result, the bending flex sensors due to the movement of the fingers has doubled up the rotation of the servo motors to mimic this movement at the dummy hand. The voltage output from the bending sensors are ranging from 0 volt to 5 volts, which are suitable for low-cost hand trainer device implementation. Through this system, the patient will have the power to control their gripping operation slowly without having a painful force from the external actuators throughout the rehabilitation process.

Ground reaction force characteristics of Tai Chi push hand.

PubMed

Chang, Yao-Ting; Chang, Jia-Hao; Huang, Chen-Fu

2014-01-01

Push Hand is an advanced training technique for the Yang-style old frame 108 forms Tai Chi Chuan. It is performed by two practitioners. To clarify how people use forces during Push Hand training, it is important to review the ground reaction force (GRF). Here, we quantify the characteristics of the GRF during Push Hand training. Kinematic data and GRF data from 10 Tai Chi Chuan practitioners (29.9 ± 7.87 years) were synchronously recorded using a three-dimensional motion analysis system (200 frames · s(-1)) and three-dimensional force plates (1000 Hz). The resultant GRF for both feet for the 0%, 50% and 100% phases of attack and defence were compared to body weight using a paired-samples t-test. The differences in the resultant GRF between the 0%, 50% and 100% phases of attack and defence were tested by one-way repeated-measures ANOVA. The significance level was set to 0.05. The total resultant GRF was almost equal to the participant's body weight in push hand. This result was consistent throughout the entire push hand process. Our results revealed that the GRF was comparable to the body weight, implying that practitioners do not push or resist their opponents during the push hand process.

Role of stag beetle jaw bending and torsion in grip on rivals.

PubMed

Goyens, Jana; Dirckx, Joris; Piessen, Maxim; Aerts, Peter

2016-01-01

In aggressive battles, the extremely large male stag beetle jaws have to withstand strongly elevated bite forces. We found several adaptations of the male Cyclommatus metallifer jaw morphology for enhanced robustness that conspecific females lack. As a result, males improve their grip on opponents and they maintain their safety factor (5.2-7.2) at the same level as that of females (6.8), despite their strongly elevated bite muscle force (3.9 times stronger). Males have a higher second moment of area and torsion constant than females, owing to an enhanced cross-sectional area and shape. These parameters also increase faster with increasing bending moment towards the jaw base in males than in females. Male jaws are more bending resistant against the bite reaction force than against perpendicular forces (which remain lower in battles). Because of the triangular cross section of the male jaw base, it twists more easily than it bends. This torsional flexibility creates a safety system against overload that, at the same time, secures a firm grip on rivals. We found no structural mechanical function of the large teeth halfway along the male jaws. Therefore, it appears that the main purpose of these teeth is a further improvement of grip on rivals. © 2016 The Author(s).

Role of stag beetle jaw bending and torsion in grip on rivals

PubMed Central

Goyens, Jana; Dirckx, Joris; Piessen, Maxim; Aerts, Peter

2016-01-01

In aggressive battles, the extremely large male stag beetle jaws have to withstand strongly elevated bite forces. We found several adaptations of the male Cyclommatus metallifer jaw morphology for enhanced robustness that conspecific females lack. As a result, males improve their grip on opponents and they maintain their safety factor (5.2–7.2) at the same level as that of females (6.8), despite their strongly elevated bite muscle force (3.9 times stronger). Males have a higher second moment of area and torsion constant than females, owing to an enhanced cross-sectional area and shape. These parameters also increase faster with increasing bending moment towards the jaw base in males than in females. Male jaws are more bending resistant against the bite reaction force than against perpendicular forces (which remain lower in battles). Because of the triangular cross section of the male jaw base, it twists more easily than it bends. This torsional flexibility creates a safety system against overload that, at the same time, secures a firm grip on rivals. We found no structural mechanical function of the large teeth halfway along the male jaws. Therefore, it appears that the main purpose of these teeth is a further improvement of grip on rivals. PMID:26763329

Relationship among maximal grip, throwing velocity and anthropometric parameters in elite water polo players.

PubMed

Ferragut, C; Vila, H; Abraldes, J A; Argudo, F; Rodriguez, N; Alcaraz, P E

2011-03-01

As independent aspects, body size, body composition, and physiological performance of elite athletes have aroused the interest of sports scientists but, unfortunately, studies that combine these aspects are scarcely avalaible in water polo. The aim of the present study was to: 1) to develop an anthropometric profile of highly skilled male Water Polo players, and 2) to identify significant relationships between these features and overhead throwing velocity in highly skilled male water polo players. Thirteen male water polo players, with a mean age of 26.10±4.82, were recruited from the Spanish Water Polo team and an anthropometric assessment on all of them was carried out. Throwing velocity was evaluated in three different situations from the 5 m-penalty line on the center of the water polo goal: A) throwing without a defender nor a goalkeeper; B) throwing with a goalkeeper only, and C) 3) armfuls running shot with goalkeeper. Maximal handgrip was also tested. Biacromial breadth shows a significative correlation with hand grip in water polo players (r=0.792; P=0.001) and also correlates with Throwing velocity (r=0.716; P<0.001). Biepicondylar femur breadth correlates significatively with hand grip (r=0.727; P<0.05) and also with throwing velocity in "throwing with goalkeeper" situation (r=0.664; P<0.05). Hand grip shows a significant correlation with throwing velocity in "throwing with goalkeeper" situation (r=0.603; P<0.05). In conclusion, body mass aspects are not related with throwing velocity in highly skilled Water Polo players. Maximal hand grip is related with throwing velocity in "throwing with goalkeeper" situation. More investigations about water polo are necessary.

Modeling the finger joint moments in a hand at the maximal isometric grip: the effects of friction.

PubMed

Wu, John Z; Dong, Ren G; McDowell, Thomas W; Welcome, Daniel E

2009-12-01

The interaction between the handle and operator's hand affects the comfort and safety of tool and machine operations. In most of the previous studies, the investigators considered only the normal contact forces. The effect of friction on the joint moments in fingers has not been analyzed. Furthermore, the observed contact forces have not been linked to the internal musculoskeletal loading in the previous experimental studies. In the current study, we proposed a universal model of a hand to evaluate the joint moments in the fingers during grasping tasks. The hand model was developed on the platform of the commercial software package AnyBody. Only four fingers (index, long, ring, and little finger) were included in the model. The anatomical structure of each finger is comprised of four phalanges (distal, middle, proximal, and metacarpal phalange). The simulations were performed using an inverse dynamics technique. The joint angles and the normal contact forces on each finger section reported by previous researchers were used as inputs, while the joint moments of each finger were predicted. The predicted trends of the dependence of the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joint moments on the cylinder diameter agree with those of the contact forces on the fingers observed in the previous experimental study. Our results show that the DIP and PIP joint moments reach their maximums at a cylinder diameter of about 31mm, which is consistent with the trend of the finger contact forces measured in the experiments. The proposed approach will be useful for simulating musculoskeletal loading in the hand for occupational activities, thereby optimizing tool-handle design.

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.

Hybrid force-velocity sliding mode control of a prosthetic hand.

PubMed

Engeberg, Erik D; Meek, Sanford G; Minor, Mark A

2008-05-01

Four different methods of hand prosthesis control are developed and examined experimentally. Open-loop control is shown to offer the least sensitivity when manipulating objects. Force feedback substantially improves upon open-loop control. However, it is shown that the inclusion of velocity and/or position feedback in a hybrid force-velocity control scheme can further improve the functionality of hand prostheses. Experimental results indicate that the sliding mode controller with force, position, and velocity feedback is less prone to unwanted force overshoot when initially grasping objects than the other controllers.

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.

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

Relationships between Mechanical Variables in the Traditional and Close-Grip Bench Press.

PubMed

Lockie, Robert G; Callaghan, Samuel J; Moreno, Matthew R; Risso, Fabrice G; Liu, Tricia M; Stage, Alyssa A; Birmingham-Babauta, Samantha A; Stokes, John J; Giuliano, Dominic V; Lazar, Adrina; Davis, DeShaun L; Orjalo, Ashley J

2017-12-01

The study aim was to determine relationships between mechanical variables in the one-repetition maximum (1RM) traditional bench press (TBP) and close-grip bench press (CGBP). Twenty resistance-trained men completed a TBP and CGBP 1RM. The TBP was performed with the preferred grip; the CGBP with a grip width of 95% biacromial distance. A linear position transducer measured: lift distance and duration; work; and peak and mean power, velocity, and force. Paired samples t-tests (p < 0.05) compared the 1RM and mechanical variables for the TBP and CGBP; effect sizes (d) were also calculated. Pearson's correlations (r; p < 0.05) computed relationships between the TBP and CGBP. 1RM, lift duration, and mean force were greater in the TBP (d = 0.30-3.20). Peak power and velocity was greater for the CGBP (d = 0.50-1.29). The 1RM TBP correlated with CGBP 1RM, power, and force (r = 0.685-0.982). TBP work correlated with CGBP 1RM, lift distance, power, force, and work (r = 0.542-0.931). TBP power correlated with CGBP 1RM, power, force, velocity, and work (r = 0.484-0.704). TBP peak and mean force related to CGBP 1RM, power, and force (r = 0.596-0.980). Due to relationships between the load, work, power, and force for the TBP and CGBP, the CGBP could provide similar strength adaptations to the TBP with long-term use. The velocity profile for the CGBP was different to that of the TBP. The CGBP could be used specifically to improve high-velocity, upper-body pushing movements.

Relationships between Mechanical Variables in the Traditional and Close-Grip Bench Press

PubMed Central

Callaghan, Samuel J.; Moreno, Matthew R.; Risso, Fabrice G.; Liu, Tricia M.; Stage, Alyssa A.; Birmingham-Babauta, Samantha A.; Stokes, John J.; Giuliano, Dominic V.; Lazar, Adrina; Davis, DeShaun L.; Orjalo, Ashley J.

2017-01-01

Abstract The study aim was to determine relationships between mechanical variables in the one-repetition maximum (1RM) traditional bench press (TBP) and close-grip bench press (CGBP). Twenty resistance-trained men completed a TBP and CGBP 1RM. The TBP was performed with the preferred grip; the CGBP with a grip width of 95% biacromial distance. A linear position transducer measured: lift distance and duration; work; and peak and mean power, velocity, and force. Paired samples t-tests (p < 0.05) compared the 1RM and mechanical variables for the TBP and CGBP; effect sizes (d) were also calculated. Pearson’s correlations (r; p < 0.05) computed relationships between the TBP and CGBP. 1RM, lift duration, and mean force were greater in the TBP (d = 0.30-3.20). Peak power and velocity was greater for the CGBP (d = 0.50-1.29). The 1RM TBP correlated with CGBP 1RM, power, and force (r = 0.685-0.982). TBP work correlated with CGBP 1RM, lift distance, power, force, and work (r = 0.542-0.931). TBP power correlated with CGBP 1RM, power, force, velocity, and work (r = 0.484-0.704). TBP peak and mean force related to CGBP 1RM, power, and force (r = 0.596-0.980). Due to relationships between the load, work, power, and force for the TBP and CGBP, the CGBP could provide similar strength adaptations to the TBP with long-term use. The velocity profile for the CGBP was different to that of the TBP. The CGBP could be used specifically to improve high-velocity, upper-body pushing movements. PMID:29339982

Effects of hand-training in persons with myotonic dystrophy type 1--a randomised controlled cross-over pilot study.

PubMed

Aldehag, Anna; Jonsson, Hans; Lindblad, Jan; Kottorp, Anders; Ansved, Tor; Kierkegaard, Marie

2013-10-01

To investigate the effects of a hand-training programme on grip, pinch and wrist force, manual dexterity and activities of daily living, in adults with myotonic dystrophy type 1 (DM1). In this randomised controlled trial with a crossover design, 35 adults with DM1 were, after stratification for grip force, assigned by lot to two groups. Group A started with 12 weeks of hand training, while group B had no intervention. After a wash-out period of 12 weeks, where none received training, the order was reversed. The Grippit® was used as primary outcome measure and the hand-held Microfet2™ myometer, the Purdue Pegboard, the Canadian Occupational Performance Measure (COPM) and the Assessment of Motor and Process Skills (AMPS) were secondary outcome measures. Assessments were performed before and after training and control periods, i.e. four times altogether. Ten persons dropped out and 13 had acceptable adherence. Intention-to-treat analyses revealed significant intervention effects for isometric wrist flexor force (p = 0.048), and for COPM performance (p = 0.047) and satisfaction (p = 0.027). On an individual level, improvements were in general showed after a training period. The hand-training programme had positive effects on wrist flexor force and self-perception of occupational performance, and of satisfaction with performance. No evident detrimental effects were shown. Myotonic dystrophy type 1 (DM1) is a slowly progressive neuromuscular disease characterised by myotonia and muscle weakness and wasting. People with DM1 are often concerned about their ability to carry out ADL and to participate in, e.g. work, sports and hobbies when they gradually become weaker. This pilot study showed that a hand-training programme improved wrist flexor force and self-perception and satisfaction of occupational performance. Resistance training of hand muscles with a silicon-based putty can be a therapy option for people with DM1 in clinical practise.

Clinical Outcomes of Living Liver Transplantation According to the Presence of Sarcopenia as Defined by Skeletal Muscle Mass, Hand Grip, and Gait Speed.

PubMed

Harimoto, N; Yoshizumi, T; Izumi, T; Motomura, T; Harada, N; Itoh, S; Ikegami, T; Uchiyama, H; Soejima, Y; Nishie, A; Kamishima, T; Kusaba, R; Shirabe, K; Maehara, Y

2017-11-01

Sarcopenia is an independent predictor of death after living-donor liver transplantation (LDLT). However, the ability of the Asian Working Group for Sarcopenia criteria for sarcopenia (defined as reduced skeletal muscle mass plus low muscle strength) to predict surgical outcomes in patients who have undergone LDLT has not been determined. This study prospectively enrolled 366 patients who underwent LDLT at Kyushu University Hospital. Skeletal muscle area (determined by computed tomography), hand-grip strength, and gait speed were measured in 102 patients before LDLT. We investigated the relationship between sarcopenia and surgical outcomes after LDLT performed in three time periods. The number of patients with lower skeletal muscle area has increased to 52.9% in recent years. The incidence of sarcopenia according to the Asian Working Group for Sarcopenia criteria was 23.5% (24/102). Patients with sarcopenia (defined by skeletal muscle area and functional parameters) had significantly lower skeletal muscle area and weaker hand-grip strength than did those without sarcopenia. Compared with non-sarcopenic patients, patients with sarcopenia also had significantly worse liver function, greater estimated blood loss, greater incidence of postoperative complications of Clavien-Dindo grade IV or greater (including amount of ascites on postoperative day 14, total bilirubin on postoperative day 14, and postoperative sepsis), and longer postoperative hospital stay. Multiple logistic regression analysis revealed sarcopenia as a significant predictor of 6-month mortality. The combination of skeletal muscle mass and function can predict surgical outcomes in LDLT patients. Copyright © 2017 Elsevier Inc. All rights reserved.

Maternal hand grip strength in pregnancy, newborn sex and birth weight.

PubMed

Żelaźniewicz, Agnieszka; Pawłowski, Bogusław

2018-04-01

Hand grip strength (HGS) is a non-invasive measure of physical strength, overall health, and nutritional status. The aim of the study was to test if HGS and its changes in pregnancy are related with offspring sex and birth weight. We conducted longitudinal study on 95 healthy pregnant women (mean age 29.57 ± 3.43). HGS was measured in each trimester. A woman's height and changes in weight in pregnancy were also measured. The information on a child's sex, birth weight and the pregnancy week at delivery were derived from hospital records. Fifty one women delivered a boy, and forty four women delivered a girl. HGS decreased from the first to the third trimester of pregnancy (F(2,188) = 15.94, p < 0.001). Women with greater HGS in each trimester were more likely to give birth to a boy (p < 0.05), and the decrease in HGS in pregnancy was comparable in the two groups of mothers (F(2,186) = 1.39, p = 0.25). HGS in pregnancy was related with offspring birth weight when controlled for a child's sex and week at delivery (F(2,182) = 3.15, p = 0.04). Maternal height also important predictor of HGS in pregnancy, and the decrease in HGS was only observed in shorter women. The results of this study indicate that HGS is a sensitive marker, differentiating the variation in physical condition in healthy, well-fed pregnant women in affluent population and pregnancy outcome (offspring sex and birth weight). Also, the result indicates that relatively taller women bear lower cost of pregnancy and are able to invest more in developing foetus. Copyright © 2018 Elsevier B.V. All rights reserved.

The Effects of Extravehicular Activity (EVA) Glove Pressure on Hand Strength

NASA Technical Reports Server (NTRS)

Mesloh, Miranda; England, Scott; Benson, Elizabeth; Thompson, Shelby; Rajulu, Sudhakar

2010-01-01

The purpose of this study was to characterize hand strength, while wearing a Phase VI Extravehicular Activity (EVA) glove in an Extravehicular Mobility Unit (EMU) suit. Three types of data were collected: hand grip, lateral pinch, and pulp-2 pinch, wider three different conditions: bare-handed, gloved with no Thermal Micrometeoroid Garment (TMG), and glove with TMG. In addition, during the gloved conditions, subjects were tested when unpressurized and pressurized (43 psi). As a percentage of bare-hand strength, the TMG condition showed reduction in grip strength to 55% unpressurized and 46% pressurized. Without the TMG, grip strength increased to 66% unpressurized and 58% pressurized of bare-hand strength. For lateral pinch strength, the reduction in strength was the same for both pressure conditions and with and without the TMG, about 8.5% of bare-hand Pulp-2 pinch strength with no TMG showed an increase to 122% unpressurized and 115% pressurized of bare-hand strength. While wearing the TMG, pulp-2 pinch strength was 115% of bare-hand strength for both pressure conditions.

Fingers' vibration transmission and grip strength preservation performance of vibration reducing gloves.

PubMed

Hamouda, K; Rakheja, S; Dewangan, K N; Marcotte, P

2018-01-01

The vibration isolation performances of vibration reducing (VR) gloves are invariably assessed in terms of power tools' handle vibration transmission to the palm of the hand using the method described in ISO 10819 (2013), while the nature of vibration transmitted to the fingers is ignored. Moreover, the VR gloves with relatively low stiffness viscoelastic materials affect the grip strength in an adverse manner. This study is aimed at performance assessments of 12 different VR gloves on the basis of handle vibration transmission to the palm and the fingers of the gloved hand, together with reduction in the grip strength. The gloves included 3 different air bladder, 3 gel, 3 hybrid, and 2 gel-foam gloves in addition to a leather glove. Two Velcro finger adapters, each instrumented with a three-axis accelerometer, were used to measure vibration responses of the index and middle fingers near the mid-phalanges. Vibration transmitted to the palm was measured using the standardized palm adapter. The vibration transmissibility responses of the VR gloves were measured in the laboratory using the instrumented cylindrical handle, also described in the standard, mounted on a vibration exciter. A total of 12 healthy male subjects participated in the study. The instrumented handle was also used to measure grip strength of the subjects with and without the VR gloves. The results of the study showed that the VR gloves, with only a few exceptions, attenuate handle vibration transmitted to the fingers only in the 10-200 Hz and amplify middle finger vibration at frequencies exceeding 200 Hz. Many of the gloves, however, provided considerable reduction in vibration transmitted to the palm, especially at higher frequencies. These suggest that the characteristics of vibration transmitted to fingers differ considerably from those at the palm. Four of the test gloves satisfied the screening criteria of the ISO 10819 (2013) based on the palm vibration alone, even though these caused

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.

Prosthetic Hand For Holding Rods, Tools, And Handles

NASA Technical Reports Server (NTRS)

Belcher, Jewell G., Jr.; Vest, Thomas W.

1995-01-01

Prosthetic hand with quick-grip/quick-release lever broadens range of specialized functions available to lower-arm amputee by providing improved capabilities for gripping rods, tools, handles, and like. Includes two stationary lower fingers opposed by one pivoting upper finger. Lever operates in conjunction with attached bracket.

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.

Pinch-force-magnification mechanism of low degree of freedom EMG prosthetic hand for children.

PubMed

Ye, Hesong; Sakoda, Shintaro; Jiang, Yinlai; Morishita, Soichiro; Yokoi, Hiroshi

2015-01-01

EMG prosthetic hands are being extensively studied for the disabled who need them not only for cosmesis but also for the functions to help them with basic daily activities. However, most EMG prosthetic hands are developed for adults. Since the early use of prosthetic hands is important for the children to accept and adapt to them, we are developing low degrees of freedom (DoF) prosthetic hand that is suitable for children. Due to the limited size of a child's hand, the servo motor which drives the MP joint are small-sized and low-power. Hence, a pinch-force-magnification mechanism is required to improve the pinch force of the EMG prosthetic hand. In this paper we designed a wire-driven mechanism which can magnify pinch force by increasing the length of the MP joint's moment arm. Pinch force measurement experiment validated that the pinch force of the prosthetic hand with the mechanism is more than twice of that of the hand with direct drive.

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.

Vibrotactile grasping force and hand aperture feedback for myoelectric forearm prosthesis users.

PubMed

Witteveen, Heidi J B; Rietman, Hans S; Veltink, Peter H

2015-06-01

User feedback about grasping force and hand aperture is very important in object handling with myoelectric forearm prostheses but is lacking in current prostheses. Vibrotactile feedback increases the performance of healthy subjects in virtual grasping tasks, but no extensive validation on potential users has been performed. Investigate the performance of upper-limb loss subjects in grasping tasks with vibrotactile stimulation, providing hand aperture, and grasping force feedback. Cross-over trial. A total of 10 subjects with upper-limb loss performed virtual grasping tasks while perceiving vibrotactile feedback. Hand aperture feedback was provided through an array of coin motors and grasping force feedback through a single miniature stimulator or an array of coin motors. Objects with varying sizes and weights had to be grasped by a virtual hand. Percentages correctly applied hand apertures and correct grasping force levels were all higher for the vibrotactile feedback condition compared to the no-feedback condition. With visual feedback, the results were always better compared to the vibrotactile feedback condition. Task durations were comparable for all feedback conditions. Vibrotactile grasping force and hand aperture feedback improves grasping performance of subjects with upper-limb loss. However, it should be investigated whether this is of additional value in daily-life tasks. This study is a first step toward the implementation of sensory vibrotactile feedback for users of myoelectric forearm prostheses. Grasping force feedback is crucial for optimal object handling, and hand aperture feedback is essential for reduction of required visual attention. Grasping performance with feedback is evaluated for the potential users. © The International Society for Prosthetics and Orthotics 2014.

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

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

A Biomechanical Assessment of Hand/Arm Force with Pneumatic Nail Gun Actuation Systems.

PubMed

Lowe, Brian D; Albers, James; Hudock, Stephen D

2014-09-01

A biomechanical model is presented, and combined with measurements of tip press force, to estimate total user hand force associated with two pneumatic nail gun trigger systems. The contact actuation trigger (CAT) can fire a nail when the user holds the trigger depressed first and then "bumps" the nail gun tip against the workpiece. With a full sequential actuation trigger (SAT) the user must press the tip against the workpiece prior to activating the trigger. The SAT is demonstrably safer in reducing traumatic injury risk, but increases the duration (and magnitude) of tip force exertion. Time integrated (cumulative) hand force was calculated for a single user from measurements of the tip contact force with the workpiece and transfer time between nails as inputs to a static model of the nail gun and workpiece in two nailing task orientations. The model shows the hand force dependence upon the orientation of the workpiece in addition to the trigger system. Based on standard time allowances from work measurement systems (i.e. Methods-Time Measurement - 1) it is proposed that efficient application of hand force with the SAT in maintaining tip contact can reduce force exertion attributable to the sequential actuation trigger to 2-8% (horizontal nailing) and 9-20% (vertical nailing) of the total hand/arm force. The present model is useful for considering differences in cumulative hand/arm force exposure between the SAT and CAT systems and may explain the appeal of the CAT trigger in reducing the user's perception of muscular effort.

A Biomechanical Assessment of Hand/Arm Force with Pneumatic Nail Gun Actuation Systems

PubMed Central

Lowe, Brian D.; Albers, James; Hudock, Stephen D.

2015-01-01

A biomechanical model is presented, and combined with measurements of tip press force, to estimate total user hand force associated with two pneumatic nail gun trigger systems. The contact actuation trigger (CAT) can fire a nail when the user holds the trigger depressed first and then “bumps” the nail gun tip against the workpiece. With a full sequential actuation trigger (SAT) the user must press the tip against the workpiece prior to activating the trigger. The SAT is demonstrably safer in reducing traumatic injury risk, but increases the duration (and magnitude) of tip force exertion. Time integrated (cumulative) hand force was calculated for a single user from measurements of the tip contact force with the workpiece and transfer time between nails as inputs to a static model of the nail gun and workpiece in two nailing task orientations. The model shows the hand force dependence upon the orientation of the workpiece in addition to the trigger system. Based on standard time allowances from work measurement systems (i.e. Methods-Time Measurement - 1) it is proposed that efficient application of hand force with the SAT in maintaining tip contact can reduce force exertion attributable to the sequential actuation trigger to 2–8% (horizontal nailing) and 9–20% (vertical nailing) of the total hand/arm force. The present model is useful for considering differences in cumulative hand/arm force exposure between the SAT and CAT systems and may explain the appeal of the CAT trigger in reducing the user’s perception of muscular effort. PMID:26321780

Effects of grip force on median nerve deformation at different wrist angles

PubMed Central

Nakashima, Hiroki; Muraki, Satoshi

2016-01-01

The present study investigated the effects of grip on changes in the median nerve cross-sectional area (MNCSA) and median nerve diameter in the radial-ulnar direction (D1) and dorsal-palmar direction (D2) at three wrist angles. Twenty-nine healthy participants (19 men [mean age, 24.2 ± 1.6 years]; 10 women [mean age, 24.0 ± 1.6 years]) were recruited. The median nerve was examined at the proximal carpal tunnel region in three grip conditions, namely finger relaxation, unclenched fist, and clenched fist. Ultrasound examinations were performed in the neutral wrist position (0°), at 30°wrist flexion, and at 30°wrist extension for both wrists. The grip condition and wrist angle showed significant main effects (p < 0.01) on the changes in the MNCSA, D1, and D2. Furthermore, significant interactions (p < 0.01) were found between the grip condition and wrist angle for the MNCSA, D1, and D2. In the neutral wrist position (0°), significant reductions in the MNCSA, D1, and D2 were observed when finger relaxation changed to unclenched fist and clenched fist conditions. Clenched fist condition caused the highest deformations in the median nerve measurements (MNCSA, approximately −25%; D1, −13%; D2, −12%). The MNCSA was significantly lower at 30°wrist flexion and 30°wrist extension than in the neutral wrist position (0°) at unclenched fist and clenched fist conditions. Notably, clenched fist condition at 30°wrist flexion showed the highest reduction of the MNCSA (−29%). In addition, 30°wrist flexion resulted in a lower D1 at clenched fist condition. In contrast, 30°wrist extension resulted in a lower D2 at both unclenched fist and clenched fist conditions. Our results suggest that unclenched fist and clenched fist conditions cause reductions in the MNCSA, D1, and D2. More importantly, unclenched fist and clenched fist conditions at 30°wrist flexion and 30°wrist extension can lead to further deformation of the median nerve. PMID:27688983

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

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.

Identification of Object Dynamics Using Hand Worn Motion and Force Sensors

PubMed Central

Kortier, Henk G.; Schepers, H. Martin; Veltink, Peter H.

2016-01-01

Emerging microelectromechanical system (MEMS)-based sensors become much more applicable for on-body measurement purposes lately. Especially, the development of a finger tip-sized tri-axial force sensor gives the opportunity to measure interaction forces between the human hand and environmental objects. We have developed a new prototype device that allows simultaneous 3D force and movement measurements at the finger and thumb tips. The combination of interaction forces and movements makes it possible to identify the dynamical characteristics of the object being handled by the hand. With this device attached to the hand, a subject manipulated mass and spring objects under varying conditions. We were able to identify and estimate the weight of two physical mass objects (0.44 kg: 29.3%±18.9% and 0.28 kg: 19.7%±10.6%) and the spring constant of a physical spring object (16.3%±12.6%). The system is a first attempt to quantify the interactions of the hand with the environment and has many potential applications in rehabilitation, ergonomics and sports. PMID:27898040

Hand rehabilitation after stroke using a wearable, high DOF, spring powered exoskeleton.

PubMed

Tianyao Chen; Lum, Peter S

2016-08-01

Stroke patients often have inappropriate finger flexor activation and finger extensor weakness, which makes it difficult to open their affected hand for functional grasp. The goal was to develop a passive, lightweight, wearable device to enable improved hand function during performance of activities of daily living. The device, HandSOME II, assists with opening the patient's hand using 11 elastic actuators that apply extension torques to finger and thumb joints. Device design and initial testing are described. A novel mechanical design applies forces orthogonal to the finger segments despite the fact that all of the device DOFs are not aligned with human joint DOF. In initial testing with seven stroke subjects with impaired hand function, use of HandSOME II significantly increased maximum extension angles and range of motion in all of the index finger joints (P<;0.05). HandSOME II allows performance of all the grip patterns used in daily activities and can be used as part of home-based therapy programs.

Design and Preliminary Feasibility Study of a Soft Robotic Glove for Hand Function Assistance in Stroke Survivors

PubMed Central

Yap, Hong Kai; Lim, Jeong Hoon; Nasrallah, Fatima; Yeow, Chen-Hua

2017-01-01

Various robotic exoskeletons have been proposed for hand function assistance during activities of daily living (ADL) of stroke survivors. However, traditional exoskeletons involve the use of complex rigid systems that impede the natural movement of joints, and thus reduce the wearability and cause discomfort to the user. The objective of this paper is to design and evaluate a soft robotic glove that is able to provide hand function assistance using fabric-reinforced soft pneumatic actuators. These actuators are made of silicone rubber which has an elastic modulus similar to human tissues. Thus, they are intrinsically soft and compliant. Upon air pressurization, they are able to support finger range of motion (ROM) and generate the desired actuation of the finger joints. In this work, the soft actuators were characterized in terms of their blocked tip force, normal and frictional grip force outputs. Combining the soft actuators and flexible textile materials, a soft robotic glove was developed for grasping assistance during ADL for stroke survivors. The glove was evaluated on five healthy participants for its assisted ROM and grip strength. Pilot test was performed in two stroke survivors to evaluate the efficacy of the glove in assisting functional grasping activities. Our results demonstrated that the actuators designed in this study could generate desired force output at a low air pressure. The glove had a high kinematic transparency and did not affect the active ROM of the finger joints when it was being worn by the participants. With the assistance of the glove, the participants were able to perform grasping actions with sufficient assisted ROM and grip strength, without any voluntary effort. Additionally, pilot test on stroke survivors demonstrated that the patient's grasping performance improved with the presence and assistance of the glove. Patient feedback questionnaires also showed high level of patient satisfaction and comfort. In conclusion, this paper

Slow but tenacious: an analysis of running and gripping performance in chameleons.

PubMed

Herrel, Anthony; Tolley, Krystal A; Measey, G John; da Silva, Jessica M; Potgieter, Daniel F; Boller, Elodie; Boistel, Renaud; Vanhooydonck, Bieke

2013-03-15

Chameleons are highly specialized and mostly arboreal lizards characterized by a suite of derived characters. The grasping feet and tail are thought to be related to the arboreal lifestyle of chameleons, yet specializations for grasping are thought to exhibit a trade-off with running ability. Indeed, previous studies have demonstrated a trade-off between running and clinging performance, with faster species being poorer clingers. Here we investigate the presence of trade-offs by measuring running and grasping performance in four species of chameleon belonging to two different clades (Chamaeleo and Bradypodion). Within each clade we selected a largely terrestrial species and a more arboreal species to test whether morphology and performance are related to habitat use. Our results show that habitat drives the evolution of morphology and performance but that some of these effects are specific to each clade. Terrestrial species in both clades show poorer grasping performance than more arboreal species and have smaller hands. Moreover, hand size best predicts gripping performance, suggesting that habitat use drives the evolution of hand morphology through its effects on performance. Arboreal species also had longer tails and better tail gripping performance. No differences in sprint speed were observed between the two Chamaeleo species. Within Bradypodion, differences in sprint speed were significant after correcting for body size, yet the arboreal species were both better sprinters and had greater clinging strength. These results suggest that previously documented trade-offs may have been caused by differences between clades (i.e. a phylogenetic effect) rather than by design conflicts between running and gripping per se.

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

Transmission of vibration through glove materials: effects of contact force.

PubMed

Md Rezali, Khairil Anas; Griffin, Michael J

2018-04-26

This study investigated effects of applied force on the apparent mass of the hand, the dynamic stiffness of glove materials and the transmission of vibration through gloves to the hand. For 10 subjects, 3 glove materials and 3 contact forces, apparent masses and glove transmissibilities were measured at the palm and at a finger at frequencies in the range 5-300 Hz. The dynamic stiffnesses of the materials were also measured. With increasing force, the dynamic stiffnesses of the materials increased, the apparent mass at the palm increased at frequencies greater than the resonance and the apparent mass at the finger increased at low frequencies. The effects of force on transmissibilities therefore differed between materials and depended on vibration frequency, but changes in apparent mass and dynamic stiffness had predictable effects on material transmissibility. Depending on the glove material, the transmission of vibration through a glove can be increased or decreased when increasing the applied force. Practitioner summary: Increasing the contact force (i.e. push force or grip force) can increase or decrease the transmission of vibration through a glove. The vibration transmissibilities of gloves should be assessed with a range of contact forces to understand their likely influence on the exposure of the hand and fingers to vibration.

Finger-Shaped GelForce: Sensor for Measuring Surface Traction Fields for Robotic Hand.

PubMed

Sato, K; Kamiyama, K; Kawakami, N; Tachi, S

2010-01-01

It is believed that the use of haptic sensors to measure the magnitude, direction, and distribution of a force will enable a robotic hand to perform dexterous operations. Therefore, we develop a new type of finger-shaped haptic sensor using GelForce technology. GelForce is a vision-based sensor that can be used to measure the distribution of force vectors, or surface traction fields. The simple structure of the GelForce enables us to develop a compact finger-shaped GelForce for the robotic hand. GelForce that is developed on the basis of an elastic theory can be used to calculate surface traction fields using a conversion equation. However, this conversion equation cannot be analytically solved when the elastic body of the sensor has a complicated shape such as the shape of a finger. Therefore, we propose an observational method and construct a prototype of the finger-shaped GelForce. By using this prototype, we evaluate the basic performance of the finger-shaped GelForce. Then, we conduct a field test by performing grasping operations using a robotic hand. The results of this test show that using the observational method, the finger-shaped GelForce can be successfully used in a robotic hand.

Association between Mediterranean diet and hand grip strength in older adult women.

PubMed

Barrea, Luigi; Muscogiuri, Giovanna; Di Somma, Carolina; Tramontano, Giovanni; De Luca, Vincenzo; Illario, Maddalena; Colao, Annamaria; Savastano, Silvia

2018-04-03

Mediterranean Diet (MD) is an eating pattern associated with multiple healthy benefits, including the conservation of skeletal muscle. Frailty is a major geriatric syndrome characterized by low muscle strength. The Hand Grip Strength (HGS) is the most frequently used indicator of muscle functional capacity for clinical purposes. The association between the adherence to the MD and HGS in elderly has not yet fully investigated. The goal of this study was to examine the association between the adherence to the MD and HGS in a not hospitalized elderly who participated in the project PERsonalised ict Supported Services for Independent Living and Active Ageing (PERSSILAA). Eighty-four elderly women were consecutively enrolled (aged 60-85 years) in this cross-sectional observational study. Anthropometric measures were evaluated. A validated 14-item questionnaire PREDIMED (PREvención con DIeta MEDiterránea) was used for the assessment of adherence to the MD. Dietary data were collected by a 7-day food records. Muscle strength was measured by HGS using a grip strength dynamometer (KERN & SOHN GmbH). The majority of participants were overweight (46.4%). An average adherence to the MD was found in 52.4% of participants, while the minority of them showed a low adherence (21.4%). HGS > cut-point of 20 kg were found in 43 subjects (51.2%). According to the adherence to MD, 39% participants with HGS values higher than cut-point presented a high adherence score compared with 14% of those with lower values of HGS (p = 0.018). The participants with HGS > cut-point presented significantly higher PREDIMED score than those with HGS < cut-point (p < 0.001). Based on ROC curves, the most sensitive and specific cut-point for the PREDIMED score to predict HGS categories was ≥8. No evident correlations were observed between HGS and age, while HGS was negatively correlated with hip circumference (r = -0.233, p = 0.033) and BMI (r = -0.219, p = 0.045), and positively

The use of clamping grips and friction pads by tree frogs for climbing curved surfaces

PubMed Central

Ji, Aihong; Yuan, Shanshan; Hill, Iain; Wang, Huan; Barnes, W. Jon P.; Dai, Zhendong; Sitti, Metin

2017-01-01

Most studies on the adhesive mechanisms of climbing animals have addressed attachment against flat surfaces, yet many animals can climb highly curved surfaces, like twigs and small branches. Here we investigated whether tree frogs use a clamping grip by recording the ground reaction forces on a cylindrical object with either a smooth or anti-adhesive, rough surface. Furthermore, we measured the contact area of fore and hindlimbs against differently sized transparent cylinders and the forces of individual pads and subarticular tubercles in restrained animals. Our study revealed that frogs use friction and normal forces of roughly a similar magnitude for holding on to cylindrical objects. When challenged with climbing a non-adhesive surface, the compressive forces between opposite legs nearly doubled, indicating a stronger clamping grip. In contrast to climbing flat surfaces, frogs increased the contact area on all limbs by engaging not just adhesive pads but also subarticular tubercles on curved surfaces. Our force measurements showed that tubercles can withstand larger shear stresses than pads. SEM images of tubercles revealed a similar structure to that of toe pads including the presence of nanopillars, though channels surrounding epithelial cells were less pronounced. The tubercles' smaller size, proximal location on the toes and shallow cells make them probably less prone to buckling and thus ideal for gripping curved surfaces. PMID:28228509

Results of telerobotic hand controller study using force information and rate control

NASA Technical Reports Server (NTRS)

Willshire, Kelli F.; Harrison, F. W.; Hogge, Edward F.; Williams, Robert L.; Soloway, Donald

1992-01-01

To increase quantified information about the effectiveness and subjective workload of force information relayed through manipulator input control devices, a space related task was performed by eight subjects with kinesthetic force feedback and/or local force accommodation through three different input control devices (i.e., hand controllers) operating in rate control mode. Task completion time, manipulator work, and subjective responses were measured. Results indicated a difference among the hand controllers. For the Honeywell six degree-of-freedom hand controller, the overall task completion times were shortest, the amount of work exerted was the least, and was the most preferred by test subjects. Neither force accommodation with or without reflection resulted in shorter task completion times or reduced work although those conditions were better than no force information for some aspects. Comparisons of results from previous studies are discussed.

Slip detection with accelerometer and tactile sensors in a robotic hand model

NASA Astrophysics Data System (ADS)

Al-Shanoon, Abdulrahman Abdulkareem S.; Anom Ahmad, Siti; Hassan, Mohd. Khair b.

2015-11-01

Grasp planning is an interesting issue in studies that dedicated efforts to investigate tactile sensors. This study investigated the physical force interaction between a tactile pressure sensor and a particular object. It also characterized object slipping during gripping operations and presented secure regripping of an object. Acceleration force was analyzed using an accelerometer sensor to establish a completely autonomous robotic hand model. An automatic feedback control system was applied to regrip the particular object when it commences to slip. Empirical findings were presented in consideration of the detection and subsequent control of the slippage situation. These findings revealed the correlation between the distance of the object slipping and the required force to regrip the object safely. This approach is similar to Hooke's law formula.

Hand-arm Vibration Effects on Performance, Tactile Acuity, and Temperature of Hand

PubMed Central

Forouharmajd, Farhad; Yadegari, Mehrdad; Ahmadvand, Masoumeh; Forouharmajd, Farshad; Pourabdian, Siamak

2017-01-01

Effects of vibration appear as mechanical and psychological disorders, including stress reactions, cognitive and movement disorders, problem in concentration and paying attention to the assigned duties. The common signs and symptoms of hand-arm vibration (HAV) in the fingers and hands may appear as pins and needles feeling, tingling, numbness, and also the loss of finger sensation and dexterity. Laboratory Virtual Instrument Engineering Workbench programming software designed for occupational vibrations measurement was used to calculate HAV acceleration. Hole steadiness test is designed to measure involuntary movement of people. V-Pieron test is designed for one of the other aspects of the psycho motor phenomena of steadiness by moving the stylus across a V-form ruler. The two points test was an experiment of touch acuity, which used a caliper by placing the two styli very close on the pad of finger knuckles. The temperature of finger skin is also measured simultaneous to the above tests. Wilcoxon test indicated that a significant decrement in hand steadiness occurred after gripping a vibrating handle for 2 min (P ≤ 0.003). Wilcoxon test also represented a significant change in errors after gripping a grinder vibratory handle (P ≤ 0.003). The differences at all of the knuckles were significant with a confidence interval percentage of 99%. There was a significant reduction in finger skin temperature before and after exposure to vibration (mean = 0.45°C, based on paired sample test). The obtained results considerably demonstrated the relation between hand performance and vibrations due to gripping a grinder. It can be concluded that an injury or accident may happen after exposure to vibrations for the fine duties, in fast actions. PMID:29204383

Hand-arm Vibration Effects on Performance, Tactile Acuity, and Temperature of Hand.

PubMed

Forouharmajd, Farhad; Yadegari, Mehrdad; Ahmadvand, Masoumeh; Forouharmajd, Farshad; Pourabdian, Siamak

2017-01-01

Effects of vibration appear as mechanical and psychological disorders, including stress reactions, cognitive and movement disorders, problem in concentration and paying attention to the assigned duties. The common signs and symptoms of hand-arm vibration (HAV) in the fingers and hands may appear as pins and needles feeling, tingling, numbness, and also the loss of finger sensation and dexterity. Laboratory Virtual Instrument Engineering Workbench programming software designed for occupational vibrations measurement was used to calculate HAV acceleration. Hole steadiness test is designed to measure involuntary movement of people. V-Pieron test is designed for one of the other aspects of the psycho motor phenomena of steadiness by moving the stylus across a V-form ruler. The two points test was an experiment of touch acuity, which used a caliper by placing the two styli very close on the pad of finger knuckles. The temperature of finger skin is also measured simultaneous to the above tests. Wilcoxon test indicated that a significant decrement in hand steadiness occurred after gripping a vibrating handle for 2 min ( P ≤ 0.003). Wilcoxon test also represented a significant change in errors after gripping a grinder vibratory handle ( P ≤ 0.003). The differences at all of the knuckles were significant with a confidence interval percentage of 99%. There was a significant reduction in finger skin temperature before and after exposure to vibration (mean = 0.45°C, based on paired sample test). The obtained results considerably demonstrated the relation between hand performance and vibrations due to gripping a grinder. It can be concluded that an injury or accident may happen after exposure to vibrations for the fine duties, in fast actions.

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.

The effect of the involvement of the dominant or non-dominant hand on grip/pinch strengths and the Levine score in patients with carpal tunnel syndrome.

PubMed

Zyluk, A; Walaszek, I

2012-06-01

The Levine questionnaire is a disease-oriented instrument developed for outcome measurement of carpal tunnel syndrome (CTS) management. The objective of this study was to compare Levine scores in patients with unilateral CTS, involving the dominant or non-dominant hand, before and after carpal tunnel release. Records of 144 patients, 126 women (87%) and 18 men (13%) aged a mean of 58 years with unilateral CTS, treated operatively, were analysed. The dominant hand was involved in 100 patients (69%), the non-dominant in 44 (31%). The parameters were analysed pre-operatively, and at 1 and 6 months post-operatively. A comparison of Levine scores in patients with the involvement of the dominant or non-dominant hand showed no statistically significant differences at baseline and any of the follow-up measurements. Statistically significant differences were noted in total grip strength at baseline and at 6 month assessments and in key-pinch strength at 1 and 6 months.

Radiographic hand osteoarthritis: patterns and associations with hand pain and function in a community-dwelling sample.

PubMed

Marshall, M; van der Windt, D; Nicholls, E; Myers, H; Hay, E; Dziedzic, K

2009-11-01

Patterns of radiographic osteoarthritis (ROA) of the hand are often examined by row, with the four joints of the thumb studied inconsistently. The objectives of this study were to determine relationships of ROA at different hand joints, use the findings to define radiographic sub-groups and investigate their associations with pain and function. Sixteen joints in each hand were scored for the presence of ROA in a community-dwelling cohort of adults, 50-years-and-over, with self-reported hand pain or problems. Principal components analysis (PCA) with varimax rotation was used to study patterns of ROA in the hand joints and identify distinct sub-groups. Differences in pain and function between these sub-groups were assessed using Australian/Canadian Osteoarthritis Index (AUSCAN), Grip Ability Test (GAT) and grip and pinch strength. PCA was undertaken on data from 592 participants and identified four components: distal interphalangeal joints (DIPs), proximal interphalangeal joints (PIPs), metacarpophalangeal joints (MCPs), thumb joints. However, the left thumb interphalangeal (IP) joint cross-loaded with the PIP and thumb groups. On this basis, participants were categorised into four radiographic sub-groups: no osteoarthritis (OA), finger only OA, thumb only OA and combined thumb and finger OA. Statistically significant differences were found between the sub-groups for AUSCAN function, and in women alone for grip and pinch strength. Participants with combined thumb and finger OA had the worst scores. Individual thumb joints can be clustered together as a joint group in ROA. Four radiographic sub-groups of hand OA can be distinguished. Pain and functional difficulties were highest in participants with both thumb and finger OA.

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 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)

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.

Stability of hand force production. I. Hand level control variables and multifinger synergies.

PubMed

Reschechtko, Sasha; Latash, Mark L

2017-12-01

We combined the theory of neural control of movement with referent coordinates and the uncontrolled manifold hypothesis to explore synergies stabilizing the hand action in accurate four-finger pressing tasks. In particular, we tested a hypothesis on two classes of synergies, those among the four fingers and those within a pair of control variables, stabilizing hand action under visual feedback and disappearing without visual feedback. Subjects performed four-finger total force and moment production tasks under visual feedback; the feedback was later partially or completely removed. The "inverse piano" device was used to lift and lower the fingers smoothly at the beginning and at the end of each trial. These data were used to compute pairs of hypothetical control variables. Intertrial analysis of variance within the finger force space was used to quantify multifinger synergies stabilizing both force and moment. A data permutation method was used to quantify synergies among control variables. Under visual feedback, synergies in the spaces of finger forces and hypothetical control variables were found to stabilize total force. Without visual feedback, the subjects showed a force drift to lower magnitudes and a moment drift toward pronation. This was accompanied by disappearance of the four-finger synergies and strong attenuation of the control variable synergies. The indexes of the two types of synergies correlated with each other. The findings are interpreted within the scheme with multiple levels of abundant variables. NEW & NOTEWORTHY We extended the idea of hierarchical control with referent spatial coordinates for the effectors and explored two types of synergies stabilizing multifinger force production tasks. We observed synergies among finger forces and synergies between hypothetical control variables that stabilized performance under visual feedback but failed to stabilize it after visual feedback had been removed. Indexes of two types of synergies correlated

Digit ratio (2D:4D), testosterone, cortisol, aggression, personality and hand-grip strength: Evidence for prenatal effects on strength.

PubMed

Ribeiro, Evaldo; Neave, Nick; Morais, Rosana Nogueiro; Kilduff, Liam; Taylor, Suzan R; Butovskaya, Marina; Fink, Bernhard; Manning, John T

2016-09-01

Digit ratio (2D:4D) is a putative marker for prenatal testosterone and is correlated with performance in many sports. Low 2D:4D has been linked to strength but the evidence is mixed and strength is also influenced by mass, testosterone, and behavioural factors. It has been hypothesised that the 2D:4D-strength correlation may be strongest in challenge conditions when short-term changes occur in steroid hormones. We tested this suggestion in men. We used a cross-over study design with a challenge (an aggressive video of rugby tackles) and control (a blank screen) condition. 89 healthy men. Finger lengths (2nd and 4th for both hands), hand-grip strength (HGS), testosterone (T), cortisol (C), aggression (Buss-Perry Aggression Questionnaire) and personality type (Ten Item Personality Measure). In both conditions participants provided saliva samples (for hormone assays). In the challenge condition there was a highly significant increase in HGS, and modest changes in T, physical aggression and emotional stability. HGS correlated negatively with left hand 2D:4D. In a multiple regression, left hand 2D:4D was negatively related to HGS and emotional stability was positively related to HGS. In the control condition HGS was not correlated with 2D:4D. In a multiple regression, BMI, physical aggression, and emotional stability were significantly related to HGS. 2D:4D is a negative correlate of strength in challenge situations. This finding may in part explain associations between 2D:4D and sports performance. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

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.

Assessment of Nutritional Status in Children With Chronic Kidney Disease Using Hand Grip Strength Tool.

PubMed

Abd El Basset Bakr, Ashraf Mohamed; Hasaneen, Bothina Mohamed; AbdelRasoul Helal Bassiouni, Dina

2018-05-03

Muscle status assessment is crucial for diagnosis of protein energy wasting PEW/cachexia in chronic kidney disease (CKD) population. Hand grip strength (HGS) has been used in muscle power assessment in adult CKD. However, no data is available about its usefulness in children with CKD. Hence, we aimed to study the reliability of HGS in reflecting the muscle power and thus, nutritional status in children with CKD. In this Observational cross sectional study we enrolled 73 CKD children; 45 had end stage kidney disease (ESKD) on hemodialysis (HD) and 28 had CKD but not on dialysis yet. Assessment of children's nutritional status was done through biochemical variables (serum albumin and serum cholesterol) and anthropometric measures (height and BMI). Body composition monitor (BCM) device was used for lean tissue mass (LTM) assessment whilst muscle power was tested by HGS tool. The study showed that 69.8% of CKD patients had HGS values below 10th percentile for age and sex. Moreover, HGS was observed to be more affected in CRI patients and those with non - glomerular causes. HGS was also found to be positively correlated to height but not to lean tissue mass or serum albumin. HGS tool can be used as a reliable bedside tool for nutritional assessment in children with CKD. Copyright © 2018 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

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

Sensing and Force-Feedback Exoskeleton (SAFE) Robotic Glove.

PubMed

Ben-Tzvi, Pinhas; Ma, Zhou

2015-11-01

This paper presents the design, implementation and experimental validation of a novel robotic haptic exoskeleton device to measure the user's hand motion and assist hand motion while remaining portable and lightweight. The device consists of a five-finger mechanism actuated with miniature DC motors through antagonistically routed cables at each finger, which act as both active and passive force actuators. The SAFE Glove is a wireless and self-contained mechatronic system that mounts over the dorsum of a bare hand and provides haptic force feedback to each finger. The glove is adaptable to a wide variety of finger sizes without constraining the range of motion. This makes it possible to accurately and comfortably track the complex motion of the finger and thumb joints associated with common movements of hand functions, including grip and release patterns. The glove can be wirelessly linked to a computer for displaying and recording the hand status through 3D Graphical User Interface (GUI) in real-time. The experimental results demonstrate that the SAFE Glove is capable of reliably modeling hand kinematics, measuring finger motion and assisting hand grasping motion. Simulation and experimental results show the potential of the proposed system in rehabilitation therapy and virtual reality applications.

Force-endurance capabilities of extravehicular activity (EVA) gloves at different pressure levels

NASA Technical Reports Server (NTRS)

Bishu, Ram R.; Klute, Glenn K.

1993-01-01

The human hand is a very useful multipurpose tool in all environments. However, performance capabilities are compromised considerably when gloves are donned. This is especially true to extravehicular activity (EVA) gloves. The primary intent was to answer the question of how long a person can perform tasks requiring certain levels of exertion. The objective was to develop grip force-endurance relations. Six subjects participated in a factorial experiment involving three hand conditions, three pressure differentials, and four levels of force exertion. The results indicate that, while the force that could be exerted depended on the glove, pressure differential, and the level of exertion, the endurance time at any exertion level depended just on the level of exertion expressed as a percentage of maximum exertion possible at that condition. The impact of these findings for practitioners as well as theoreticians is discussed.

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)

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.

Hand-grip strength among older adults in Singapore: a comparison with international norms and associative factors.

PubMed

Ong, Hui Lin; Abdin, Edimansyah; Chua, Boon Yiang; Zhang, Yunjue; Seow, Esmond; Vaingankar, Janhavi Ajit; Chong, Siow Ann; Subramaniam, Mythily

2017-08-04

Hand-grip strength (HGS) serves as a proxy measure for muscle function and physical health. Studies have shown that low HGS is associated with common age-related disorders including frailty and sarcopenia. The aim of the present study was to establish the normative values of HGS among older adults in Singapore and to compare it with data from Western and other Asian countries. The study also aimed to explore the sociodemographic and anthropometric correlates of HGS. Data were collected from 2043 men and women aged 60 years and above who took part in the Well-being of the Singapore Elderly study in 2013. HGS was obtained using a Jamar Plus + digital hand dynamometer. Normative data were stratified by; 5-year age groups, sex and ethnicity. Relationships between the HGS with various sociodemographic and anthropometric correlates were examined using multiple linear regression analysis. The mean HGS demonstrate a decreasing trend with increased age across all ethnic groups and sexes. HGS among Singapore older adults were relatively low compared to Western and other Asian countries. Males in the youngest age group (60-64) and of Chinese ethnicity attained greater HGS values than their counterparts. When the regression analysis was stratified for sex, significant associations were found between height, upper arm circumference with HGS in the males sample, and between height, weight, waist circumference and HGS in the females sample. Older adults in Singapore have a relatively weak HGS compared to other countries. Greater height and weight, and smaller waist circumference are independently associated with greater HGS in females but not males. These results facilitate the interpretation of HGS conducting using Jamar digital-type dynamometers among the older adults in Singapore.

Gripping characteristics of an electromagnetically activated magnetorheological fluid-based gripper

NASA Astrophysics Data System (ADS)

Choi, Young T.; Hartzell, Christine M.; Leps, Thomas; Wereley, Norman M.

2018-05-01

The design and test of a magnetorheological fluid (MRF)-based universal gripper (MR gripper) are presented in this study. The MR gripper was developed to have a simple design, but with the ability to produce reliable gripping and handling of a wide range of simple objects. The MR gripper design consists of a bladder mounted atop an electromagnet, where the bladder is filled with an MRF, which was formulated to have long-term stable sedimentation stability, that was synthesized using a high viscosity linear polysiloxane (HVLP) carrier fluid with a carbonyl iron particle (CIP) volume fraction of 35%. Two bladders were fabricated: a magnetizable bladder using a magnetorheological elastomer (MRE), and a passive (non-magnetizable) silicone rubber bladder. The holding force and applied (initial compression) force of the MR gripper for a bladder fill volume of 75% were experimentally measured, for both magnetizable and passive bladders, using a servohydraulic material testing machine for a range of objects. The gripping performance of the MR gripper using an MRE bladder was compared to that of the MR gripper using a passive bladder.

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.

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)

Why pens have rubbery grips

NASA Astrophysics Data System (ADS)

Dzidek, Brygida; Bochereau, Séréna; Johnson, Simon A.; Hayward, Vincent; Adams, Michael J.

2017-10-01

The process by which human fingers gives rise to stable contacts with smooth, hard objects is surprisingly slow. Using high-resolution imaging, we found that, when pressed against glass, the actual contact made by finger pad ridges evolved over time following a first-order kinetics relationship. This evolution was the result of a two-stage coalescence process of microscopic junctions made between the keratin of the stratum corneum of the skin and the glass surface. This process was driven by the secretion of moisture from the sweat glands, since increased hydration in stratum corneum causes it to become softer. Saturation was typically reached within 20 s of loading the contact, regardless of the initial moisture state of the finger and of the normal force applied. Hence, the gross contact area, frequently used as a benchmark quantity in grip and perceptual studies, is a poor reflection of the actual contact mechanics that take place between human fingers and smooth, impermeable surfaces. In contrast, the formation of a steady-state contact area is almost instantaneous if the counter surface is soft relative to keratin in a dry state. It is for this reason that elastomers are commonly used to coat grip surfaces.

Design of a force reflecting hand controller for space telemanipulation studies

NASA Technical Reports Server (NTRS)

Paines, J. D. B.

1987-01-01

The potential importance of space telemanipulator systems is reviewed, along with past studies of master-slave manipulation using a generalized force reflecting master arm. Problems concerning their dynamic interaction with the human operator have been revealed in the use of these systems, with marked differences between 1-g and simulated weightless conditions. A study is outlined to investigate the optimization of the man machine dynamics of master-slave manipulation, and a set of specifications is determined for the apparatus necessary to perform this investigation. This apparatus is a one degree of freedom force reflecting hand controller with closed loop servo control which enables it to simulate arbitrary dynamic properties to high bandwidth. Design of the complete system and its performance is discussed. Finally, the experimental adjustment of the hand controller dynamics for smooth manual control performance with good operator force perception is described, resulting in low inertia, viscously damped hand controller dynamics.

The exploded hand syndrome: a report of five industrial injury cases.

PubMed

Al-Qattan, M M

2013-10-01

The term 'exploded hand syndrome' refers to a specific type of crush injury to the hand in which a high compressive force excessively flattens the hand leading to thenar muscle extrusion through burst lacerations. Out of 89 crushed hands seen over a period of seven years, only five had exploded hand syndrome. They were all male industrial workers ranging in age between 24 and 55 years. All patients had thenar muscle extrusion. Other concurrent injuries included fractures/dislocations, compartment syndrome, and ischaemia. All patients were treated by excision of the extruded intrinsic muscles, as well as primary management of concurrent injuries. All patients had functional assessment including: motor power and sensory testing, range of motion of hand joints, and the quick DASH score. Objective testing showed reduced sensibility in the thumb, reduced grip strength (mean 52% of contralateral hand), reduced pinch strength (mean of 27% of contralateral hand), reduced thumb opposition (the mean Kapandji Score was 5 out of 10), and deficits in the range of motion of the metacarpophalangeal and interphalangeal joints of the thumb. The quick DASH score ranged from 11 to 49 and only two patients were able to go back to regular manual work.

Grip form and graphomotor control in preschool children.

PubMed

Burton, A W; Dancisak, M J

2000-01-01

The purpose of this study was to examine the utility of the grip scale presented by Schneck and Henderson, the effect of grip form on drawing accuracy, and the effect of implement diameter on grip form and drawing accuracy. Sixty boys and girls who were 3, 4, and 5 years of age performed 20 trials of a precision drawing task, 4 trials each with five implements of varying diameters (4.7, 7.9, 11.1, 14.3, and 17.5 mm). First, all 1,200 grips could be coded according to Schneck and Henderson's 10-grip whole-configuration assessment system, but the interrater reliability was lower than expected (.67 proportion of perfect agreement). Second, using Schneck's five-level scoring system, the level of grip significantly affected drawing accuracy, with the highest grip level used most often with the highest accuracy scores and the lowest observed grip level used most often with the lowest accuracy scores. Third, increasing implement diameter led to significantly lower level grips but did not significantly affect accuracy. Therapists are recommended to use Schneck and Henderson's 10-grip scale only for documenting the persons' grips and changes in their grips, but if comparisons between individual persons are desired, then Schneck's five-level scale, which affords greater generalizability, should be used. Further, children with graphomotor performance deficits are not likely to benefit from grip manipulations because such strategies were shown to make better only performance that is already good.

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)

Compensatory changes accompanying chronic forced use of the nondominant hand by unilateral amputees.

PubMed

Philip, Benjamin A; Frey, Scott H

2014-03-05

Amputation of the dominant hand forces patients to use the nondominant hand exclusively, including for tasks (e.g., writing and drawing) that were formerly the sole domain of the dominant hand. The behavioral and neurological effects of this chronic forced use of the nondominant hand remain largely unknown. Yet, these effects may shed light on the potential to compensate for degradation or loss of dominant hand function, as well as the mechanisms that support motor learning under conditions of very long-term training. We used a novel precision drawing task and fMRI to investigate 8 adult human amputees with chronic (mean 33 years) unilateral dominant (right) hand absence, and right-handed matched controls (8 for fMRI, 19 for behavior). Amputees' precision drawing performances with their left hands reached levels of smoothness (associated with left hemisphere control), acceleration time (associated with right hemisphere control), and speed equivalent to controls' right hands, whereas accuracy maintained a level comparable with controls' left hands. This compensation is supported by an experience-dependent shift from heavy reliance on the dorsodorsal parietofrontal pathway (feedback control) to the ventrodorsal pathway and prefrontal regions involved in the cognitive control of goal-directed actions. Relative to controls, amputees also showed increased activity within the former cortical sensorimotor hand territory in the left (ipsilateral) hemisphere. These data demonstrate that, with chronic and exclusive forced use, the speed and quality of nondominant hand precision endpoint control in drawing can achieve levels nearly comparable with the dominant hand.

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.

Biomechanically determined hand force limits protecting the low back during occupational pushing and pulling tasks.

PubMed

Weston, Eric B; Aurand, Alexander; Dufour, Jonathan S; Knapik, Gregory G; Marras, William S

2018-06-01

Though biomechanically determined guidelines exist for lifting, existing recommendations for pushing and pulling were developed using a psychophysical approach. The current study aimed to establish objective hand force limits based on the results of a biomechanical assessment of the forces on the lumbar spine during occupational pushing and pulling activities. Sixty-two subjects performed pushing and pulling tasks in a laboratory setting. An electromyography-assisted biomechanical model estimated spinal loads, while hand force and turning torque were measured via hand transducers. Mixed modelling techniques correlated spinal load with hand force or torque throughout a wide range of exposures in order to develop biomechanically determined hand force and torque limits. Exertion type, exertion direction, handle height and their interactions significantly influenced dependent measures of spinal load, hand force and turning torque. The biomechanically determined guidelines presented herein are up to 30% lower than comparable psychophysically derived limits and particularly more protective for straight pushing. Practitioner Summary: This study utilises a biomechanical model to develop objective biomechanically determined push/pull risk limits assessed via hand forces and turning torque. These limits can be up to 30% lower than existing psychophysically determined pushing and pulling recommendations. Practitioners should consider implementing these guidelines in both risk assessment and workplace design moving forward.

Vision-Based Pose Estimation for Robot-Mediated Hand Telerehabilitation.

PubMed

Airò Farulla, Giuseppe; Pianu, Daniele; Cempini, Marco; Cortese, Mario; Russo, Ludovico O; Indaco, Marco; Nerino, Roberto; Chimienti, Antonio; Oddo, Calogero M; Vitiello, Nicola

2016-02-05

Vision-based Pose Estimation (VPE) represents a non-invasive solution to allow a smooth and natural interaction between a human user and a robotic system, without requiring complex calibration procedures. Moreover, VPE interfaces are gaining momentum as they are highly intuitive, such that they can be used from untrained personnel (e.g., a generic caregiver) even in delicate tasks as rehabilitation exercises. In this paper, we present a novel master-slave setup for hand telerehabilitation with an intuitive and simple interface for remote control of a wearable hand exoskeleton, named HX. While performing rehabilitative exercises, the master unit evaluates the 3D position of a human operator's hand joints in real-time using only a RGB-D camera, and commands remotely the slave exoskeleton. Within the slave unit, the exoskeleton replicates hand movements and an external grip sensor records interaction forces, that are fed back to the operator-therapist, allowing a direct real-time assessment of the rehabilitative task. Experimental data collected with an operator and six volunteers are provided to show the feasibility of the proposed system and its performances. The results demonstrate that, leveraging on our system, the operator was able to directly control volunteers' hands movements.

The Relationship of Digit Ratio (2D:4D) with Cerebral Lateralization and Grip Strength in Elite Swimmers

ERIC Educational Resources Information Center

Acar, Hakan; Eler, Nebahat

2018-01-01

The index finger and the 4th finger ratio (2D:4D) is the indicator of the prenatal testosterone. The aim of this study is to investigate the relationship between 2D:4D, hand preference and hand grip strength in swimmers. A total of 80 elite swimmers, participated in the study. Height, body weight, body mass index (BMI), hand 2D:4D finger…

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.

Feasibility study: Effect of hand resistance exercise on handwriting in Parkinson's disease and essential tremor.

PubMed

Bryant, Mon S; Workman, Craig D; Jamal, Fariha; Meng, Hao; Jackson, George R

A single group, repeated measures design was used. Tremor can lead to impaired hand function in patients with Parkinson's disease (PD) and essential tremor (ET). Difficulty with handwriting is a common complaint in these patients suffering from hand tremors. The effect of hand resistance exercise on handwriting is unknown. To explore the influence of 6 weeks of home-based hand resistance exercise on handwriting in individuals with PD and ET. Nine individuals with PD and 9 with ET participated in the study. The average age was 65.3 (6.0) years with an average disease duration of 7.8 years. Participants were instructed to perform a home-based, hand and arm resistance exercise program 3 times a week for 6 weeks. Samples of the area of handwriting and maximal grip strength were measured at baseline and after 6 weeks of exercise. The area of the handwriting sample and maximal grip strength measured before and after 6 weeks were compared. Mean grip strength of the participants with PD improved after 6 weeks of hand resistance exercise (P = .031), but grip strength did not change in ET (P = .091). The size of the handwriting samples (words and sentences) did not change after exercise in either participants with PD or ET. Micrographia in patients with PD and macrographia in patients with ET represent complex fine motor skills. More research is needed to understand what therapies could be effective in modifying the size and quality of handwriting. The purpose of this feasibility study was to explore the influence of home-based wrist resistance exercise on handwriting in individuals with PD and ET. Despite small gains in grip strength, the size of the handwriting samples (words and sentences) did not change for patients with PD or ET following a 6-week home-based hand resistance exercise program. Published by Elsevier Inc.

Effect of skin hydration on the dynamics of fingertip gripping contact.

PubMed

André, T; Lévesque, V; Hayward, V; Lefèvre, P; Thonnard, J-L

2011-11-07

The dynamics of fingertip contact manifest themselves in the complex skin movements observed during the transition from a stuck state to a fully developed slip. While investigating this transition, we found that it depended on skin hydration. To quantify this dependency, we asked subjects to slide their index fingertip on a glass surface while keeping the normal component of the interaction force constant with the help of visual feedback. Skin deformation inside the contact region was imaged with an optical apparatus that allowed us to quantify the relative sizes of the slipping and sticking regions. The ratio of the stuck skin area to the total contact area decreased linearly from 1 to 0 when the tangential force component increased from 0 to a maximum. The slope of this relationship was inversely correlated to the normal force component. The skin hydration level dramatically affected the dynamics of the contact encapsulated in the course of evolution from sticking to slipping. The specific effect was to reduce the tendency of a contact to slip, regardless of the variations of the coefficient of friction. Since grips were more unstable under dry skin conditions, our results suggest that the nervous system responds to dry skin by exaggerated grip forces that cannot be simply explained by a change in the coefficient of friction.

Effect of skin hydration on the dynamics of fingertip gripping contact

PubMed Central

André, T.; Lévesque, V.; Hayward, V.; Lefèvre, P.; Thonnard, J.-L.

2011-01-01

The dynamics of fingertip contact manifest themselves in the complex skin movements observed during the transition from a stuck state to a fully developed slip. While investigating this transition, we found that it depended on skin hydration. To quantify this dependency, we asked subjects to slide their index fingertip on a glass surface while keeping the normal component of the interaction force constant with the help of visual feedback. Skin deformation inside the contact region was imaged with an optical apparatus that allowed us to quantify the relative sizes of the slipping and sticking regions. The ratio of the stuck skin area to the total contact area decreased linearly from 1 to 0 when the tangential force component increased from 0 to a maximum. The slope of this relationship was inversely correlated to the normal force component. The skin hydration level dramatically affected the dynamics of the contact encapsulated in the course of evolution from sticking to slipping. The specific effect was to reduce the tendency of a contact to slip, regardless of the variations of the coefficient of friction. Since grips were more unstable under dry skin conditions, our results suggest that the nervous system responds to dry skin by exaggerated grip forces that cannot be simply explained by a change in the coefficient of friction. PMID:21490002

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

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

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.

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)

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.

Change in the temporal coordination of the finger joints with ulnar nerve block during different power grips analyzed with a sensor glove.

PubMed

Wachter, N J; Mentzel, M; Häderer, C; Krischak, G D; Gülke, J

2018-02-01

Ulnar nerve injuries can cause deficient hand movement patterns. Their assessment is important for diagnosis and rehabilitation in hand surgery cases. The purpose of this study was to quantify the changes in temporal coordination of the finger joints during different power grips with an ulnar nerve block by means of a sensor glove. In 21 healthy subjects, the onset and end of the active flexion of the 14 finger joints when gripping objects of different diameters was recorded by a sensor glove. The measurement was repeated after an ulnar nerve block was applied in a standardized setting. The change in the temporal coordination of the metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints with and without the nerve block was calculated within the same subject. In healthy subjects, the MCP joints started their movement prior to the PIP joints in the middle and ring finger, whereas this occurred in the reverse order at the index and little finger. The DIP joint onset was significantly delayed (P<0.01). With the ulnar nerve block, this coordination shifted towards simultaneous onset of all joints, independent of the grip diameter. The thumb and index finger were affected the least. With an ulnar nerve block, the PIP joints completed their movement prior to the MCP joints when gripping small objects (G1 and G2), whereas the order was reversed with larger objects (G3 and G4). The alterations with ulnar nerve block affected mainly the little finger when gripping small objects. With larger diameter objects, all fingers had a significant delay at the end of the PIP joint movement relative to the MCP and DIP joints, and the PIP and DIP joint sequence was reversed (P<0.01). Based on the significant changes in temporal coordination of finger flexion during different power grips, there are biomechanical effects of loss of function of the intrinsic muscles caused by an ulnar nerve block on the fine motor skills of the hand. This can be

Bimanual Force Coordination in Children with Spastic Unilateral Cerebral Palsy

ERIC Educational Resources Information Center

Smits-Engelsman, B. C. M.; Klingels, K.; Feys, H.

2011-01-01

In this study bimanual grip-force coordination was quantified using a novel "Gripper" system that records grip forces produced while holding a lower and upper unit, in combination with the lift force necessary to separate these units. Children with unilateral cerebral palsy (CP) (aged 5-14 years, n = 12) were compared to age matched typically…

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)

Validation of the questionnaire on hand function assessment in leprosy.

PubMed

Ferreira, Telma Leonel; Alvarez, Rosicler Rocha Aiza; Virmond, Marcos da Cunha Lopes

2012-06-01

To validate the psychometric properties of the questionnaire on hand function assessment in leprosy. Study conducted with a convenience sample of 101 consecutive patients in Brasília (Central-Western Brazil), from June 2008 to July 2009. The individuals were adults affected by leprosy, with impairment of the ulnar, median and radial nerves. Interobservers and intraobserver reproducibility was analyzed through successive interviews, and construct validity was analyzed through association between age, clinical form of leprosy, duration of nerve injury, grip and pinch strength measured with a dynamometer, sensibility test performed with Semmes-Weinstein monofilaments and manual ability assessment using the Jebsen test of hand function. Pondered kappa coefficient was calculated and a Bland-Altman plot was constructed to assess the reproducibility of the instrument. For internal consistency, Cronbach's alpha coefficient was utilized. Pearson's correlation coefficient was calculated and a multiple regression model was used. The pondered kappa values for interobservers and intraobserver assessments ranged from 0.86 to 0.97 and from 0.85 to 0.97, respectively. The value of Cronbach's alpha coefficient was 0.967. Pearson's correlation coefficient showed an association (p < 0.001) among duration of nerve injury, grip and pinch strength, cutaneous sensibility and mean score in the Jebsen Test. The mean score of the questionnaire on hand functional assessment in leprosy was associated with operational classification of leprosy, duration of nerve injury, grip strength, cutaneous sensibility and manual ability (p < 0.0001 for the model as a whole). The questionnaire on hand functional assessment in leprosy presents almost perfect interobservers and intraobserver reproducibility, high internal consistency and correlation with operational classification of leprosy, duration of nerve injury, grip strength, cutaneous sensibility in the hands and manual ability.

The influence of respiratory acid-base changes on muscle performance and excitability of the sarcolemma during strenuous intermittent hand grip exercise.

PubMed

Hilbert, M; Shushakov, V; Maassen, N

2012-02-01

Acidification has been reported to provide protective effects on force production in vitro. Thus, in this study, we tested if respiratory acid-base changes influence muscle function and excitability in vivo. Nine subjects performed strenuous, intermittent hand grip exercises (10 cycles of 15 s of work/45 s of rest) under respiratory acidosis by CO(2) rebreathing, alkalosis by hyperventilation, or control. The Pco(2), pH, K(+) concentration ([K(+)]), and Na(+) concentration were measured in venous and arterialized blood. Compound action potentials (M-wave) were elicited to examine the excitability of the sarcolemma. The surface electromyogram (EMG) was recorded to estimate the central drive to the muscle. The lowest venous pH during the exercise period was 7.24 ± 0.03 in controls, 7.31 ± 0.05 with alkalosis, and 7.17 ± 0.04 with acidosis (P < 0.001). The venous [K(+)] rose to similar maximum values in all conditions (6.2 ± 0.8 mmol/l). The acidification reduced the decline in contraction speed (P < 0.001) but decreased the M-wave area to 73.4 ± 19.8% (P < 0.001) of the initial value. After the first exercise cycle, the M-wave area was smaller with acidosis than with alkalosis, and, after the second cycle, it was smaller with acidosis than with the control condition (P < 0.001). The duration of the M-wave was not affected. Acidification diminished the reduction in performance, although the M-wave area during exercise was decreased. Respiratory alkalosis stabilized the M-wave area without influencing performance. Thus, we did not find a direct link between performance and alteration of excitability of the sarcolemma due to changes in pH in vivo.

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.

The determination of the operating range of a twin-grip control yoke through biomechanical means

NASA Technical Reports Server (NTRS)

Gaertner, K. P.

1978-01-01

A twin-grip control yoke was designed as an ergonomic case study that allows dual axis control inputs, both axes being rotational. Inputs are effected by rotating the grips. How the handles were designed with respect to their shape and size and how the angular range of the control yoke in both rotational axes was evaluated. The control yoke which requires two-hand operation was tested to determine its operating range. The intention of this investigation was to find out the optimal form of the control yoke and the maximum permissible range in both rotating axes. In these experiments controls had no spring resistance.

GRiP - A flexible approach for calculating risk as a function of consequence, vulnerability, and threat.

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

Whitfield, R. G.; Buehring, W. A.; Bassett, G. W.

2011-04-08

Get a GRiP (Gravitational Risk Procedure) on risk by using an approach inspired by the physics of gravitational forces between body masses! In April 2010, U.S. Department of Homeland Security Special Events staff (Protective Security Advisors [PSAs]) expressed concern about how to calculate risk given measures of consequence, vulnerability, and threat. The PSAs believed that it is not 'right' to assign zero risk, as a multiplicative formula would imply, to cases in which the threat is reported to be extremely small, and perhaps could even be assigned a value of zero, but for which consequences and vulnerability are potentially high.more » They needed a different way to aggregate the components into an overall measure of risk. To address these concerns, GRiP was proposed and developed. The inspiration for GRiP is Sir Isaac Newton's Universal Law of Gravitation: the attractive force between two bodies is directly proportional to the product of their masses and inversely proportional to the squares of the distance between them. The total force on one body is the sum of the forces from 'other bodies' that influence that body. In the case of risk, the 'other bodies' are the components of risk (R): consequence, vulnerability, and threat (which we denote as C, V, and T, respectively). GRiP treats risk as if it were a body within a cube. Each vertex (corner) of the cube represents one of the eight combinations of minimum and maximum 'values' for consequence, vulnerability, and threat. The risk at each of the vertices is a variable that can be set. Naturally, maximum risk occurs when consequence, vulnerability, and threat are at their maximum values; minimum risk occurs when they are at their minimum values. Analogous to gravitational forces among body masses, the GRiP formula for risk states that the risk at any interior point of the box depends on the squares of the distances from that point to each of the eight vertices. The risk value at an interior (movable) point

Exploration of Force Myography and surface Electromyography in hand gesture classification.

PubMed

Jiang, Xianta; Merhi, Lukas-Karim; Xiao, Zhen Gang; Menon, Carlo

2017-03-01

Whereas pressure sensors increasingly have received attention as a non-invasive interface for hand gesture recognition, their performance has not been comprehensively evaluated. This work examined the performance of hand gesture classification using Force Myography (FMG) and surface Electromyography (sEMG) technologies by performing 3 sets of 48 hand gestures using a prototyped FMG band and an array of commercial sEMG sensors worn both on the wrist and forearm simultaneously. The results show that the FMG band achieved classification accuracies as good as the high quality, commercially available, sEMG system on both wrist and forearm positions; specifically, by only using 8 Force Sensitive Resisters (FSRs), the FMG band achieved accuracies of 91.2% and 83.5% in classifying the 48 hand gestures in cross-validation and cross-trial evaluations, which were higher than those of sEMG (84.6% and 79.1%). By using all 16 FSRs on the band, our device achieved high accuracies of 96.7% and 89.4% in cross-validation and cross-trial evaluations. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Significance of finger forces and kinematics during handwriting in writer's cramp.

PubMed

Hermsdörfer, Joachim; Marquardt, Christian; Schneider, Alexandra S; Fürholzer, Waltraud; Baur, Barbara

2011-08-01

Muscular hyperactivity during handwriting, irregular and jerky scripts, as well as awkward and slowed pen movements are the cardinal symptoms of writer's cramp. Accordingly, impaired kinematics and increased force have been reported in writer's cramp. However, the relationship between these symptoms has rarely been investigated. In addition, measurements of finger forces have been restricted to the vertical pen pressure. In the present study, the pen of a graphic tablet was equipped with a force sensor matrix to measure also the grip force produced against the pen barrel despite highly variable pen grips of the patients. Kinematics of writing movements, vertical pen pressure, and grip force were compared in 27 patients with writer's cramp and normal control writers during writing of a test sentence. As expected, all measures revealed a significantly worse writing performance in the patients compared to the control subjects. Exaggerated forces were more frequent than abnormal kinematics, and evidenced by prolonged movement times and reduced writing frequencies. Correlations were found neither between kinematics and force measures nor between the two forces. Interestingly, patients relaxed the grip force during short periods of non-writing by the same relative amount as control subjects. The finding of a large heterogeneity of performances patterns in writer's cramp may reflect the variability of dystonic symptoms as well as the highly variable compensatory strategies of individual patients. Measurements of finger force and in particular of the grip force are valuable and important descriptors of individual impairment characteristics that are independent of writing kinematics. Copyright © 2010 Elsevier B.V. All rights reserved.

The Grip of Gravity

NASA Astrophysics Data System (ADS)

Gondhalekar, Prabhakar

2001-09-01

Gravity is one of the most inexplicable forces of nature, controlling everything, from the expansion of the Universe to the ebb and flow of ocean tides. The search for the laws of motion and gravitation began more than two thousand years ago, a quest that Prabhakar Gondhalekar recounts in The Grip of Gravity. Beginning with Aristotle and concluding with Planck, Gondhalekar outlines a 'genealogy' of gravity and lucidly explains how previous explanations have shaped the most recent development in the field, string theory. In this work, physicist and astronomer Gondhalekar describes experiments, both planned and proposed, and clearly explains natural phenomena like ocean tides, seasons, ice ages, the formation of planets, stars, and exotic objects like black holes and neutron stars, which are all controlled by gravity. Including anecdotes and thumb-nail sketches of the personalities involved, The Grip of Gravity provides an introduction to the foundation of modern physics and shows how the current developments in string theory may lead to a new and radical interpretation of gravity. Prabhakar Gondhalekar is an Honorary Fellow in the Department of Physics and Astronomy, University College, London. Until his retirement in 1998, he was the head of the Space Astronomy Group at the Rutherford Appleton Laboratory, where he had been a researcher for 18 years. His research has included a number of topics in galactic and extragalactic astronomy, with his major work focusing on the interstellar medium and active galactic nuclei. Gondhalekar has been awarded Royal Society, Leverhulme Trust, and NATO Research Fellowships to do research in universities in the United States and Israel.

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

GRIP Experiment 2010

NASA Image and Video Library

2010-08-14

Jeffrey Beyon, lower right, and Paul Joseph Petzar, right, researchers from NASA's Langley Research Center, speak with Ramesh Kakar right, of the NASA Earth Science Division as they 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)

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

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

Effects of Isometric Hand-Grip Muscle Contraction on Young Adults' Free Recall and Recognition Memory.

PubMed

Tomporowski, Phillip D; Albrecht, Chelesa; Pendleton, Daniel M

2017-03-01

The purpose of this study was to determine if physical arousal produced by isometric hand-dynamometer contraction performed during word-list learning affects young adults' free recall or recognition memory. Twenty-four young adults (12 female; M age  = 22 years) were presented with 4 20-item word lists. Moderate arousal was induced in 12 adults by an initial 30-s maximal hand-dynamometer squeeze with force productions of 50% maximum; low arousal was induced in 12 adults by an initial 1-s maximal dynamometer squeeze with force production of 10% maximum during learning. Memory performances following dual-task conditions experienced during the encoding, consolidation, and recall phases of learning were compared to a single-task control condition during which words were learned in the absence of isometric exercise. Planned contrasts revealed that arousal coinciding with word encoding led to significantly poorer immediate recall, F(1, 23) = 10.13, p < .05, [Formula: see text] = .31, delayed free recall, F(1, 23) = 15.81, p < .05, [Formula: see text] = .41, and recognition memory, F(1, 23) = 6.07, p < .05, [Formula: see text] = .21, compared with when there was no arousal. Neither arousal condition facilitated participants' memory performance. The reduction in long-term memory performance specific to the encoding phase of learning is explained in terms of the dual-task attentional demands placed on participants.

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

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

Vision-Based Pose Estimation for Robot-Mediated Hand Telerehabilitation

PubMed Central

Airò Farulla, Giuseppe; Pianu, Daniele; Cempini, Marco; Cortese, Mario; Russo, Ludovico O.; Indaco, Marco; Nerino, Roberto; Chimienti, Antonio; Oddo, Calogero M.; Vitiello, Nicola

2016-01-01

Vision-based Pose Estimation (VPE) represents a non-invasive solution to allow a smooth and natural interaction between a human user and a robotic system, without requiring complex calibration procedures. Moreover, VPE interfaces are gaining momentum as they are highly intuitive, such that they can be used from untrained personnel (e.g., a generic caregiver) even in delicate tasks as rehabilitation exercises. In this paper, we present a novel master–slave setup for hand telerehabilitation with an intuitive and simple interface for remote control of a wearable hand exoskeleton, named HX. While performing rehabilitative exercises, the master unit evaluates the 3D position of a human operator’s hand joints in real-time using only a RGB-D camera, and commands remotely the slave exoskeleton. Within the slave unit, the exoskeleton replicates hand movements and an external grip sensor records interaction forces, that are fed back to the operator-therapist, allowing a direct real-time assessment of the rehabilitative task. Experimental data collected with an operator and six volunteers are provided to show the feasibility of the proposed system and its performances. The results demonstrate that, leveraging on our system, the operator was able to directly control volunteers’ hands movements. PMID:26861333

One-Channel Surface Electromyography Decomposition for Muscle Force Estimation.

PubMed

Sun, Wentao; Zhu, Jinying; Jiang, Yinlai; Yokoi, Hiroshi; Huang, Qiang

2018-01-01

Estimating muscle force by surface electromyography (sEMG) is a non-invasive and flexible way to diagnose biomechanical diseases and control assistive devices such as prosthetic hands. To estimate muscle force using sEMG, a supervised method is commonly adopted. This requires simultaneous recording of sEMG signals and muscle force measured by additional devices to tune the variables involved. However, recording the muscle force of the lost limb of an amputee is challenging, and the supervised method has limitations in this regard. Although the unsupervised method does not require muscle force recording, it suffers from low accuracy due to a lack of reference data. To achieve accurate and easy estimation of muscle force by the unsupervised method, we propose a decomposition of one-channel sEMG signals into constituent motor unit action potentials (MUAPs) in two steps: (1) learning an orthogonal basis of sEMG signals through reconstruction independent component analysis; (2) extracting spike-like MUAPs from the basis vectors. Nine healthy subjects were recruited to evaluate the accuracy of the proposed approach in estimating muscle force of the biceps brachii. The results demonstrated that the proposed approach based on decomposed MUAPs explains more than 80% of the muscle force variability recorded at an arbitrary force level, while the conventional amplitude-based approach explains only 62.3% of this variability. With the proposed approach, we were also able to achieve grip force control of a prosthetic hand, which is one of the most important clinical applications of the unsupervised method. Experiments on two trans-radial amputees indicated that the proposed approach improves the performance of the prosthetic hand in grasping everyday objects.

Frequency specific activity in subthalamic nucleus correlates with hand bradykinesia in Parkinson's disease.

PubMed

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

2013-02-01

Local field potential recordings made from the basal ganglia of patients undergoing deep brain stimulation have suggested that frequency specific activity is involved in determining the rate of force development and the peak force at the outset of a movement. However, the extent to which the basal ganglia might be involved in motor performance later on in a sustained contraction is less clear. We therefore recorded from the subthalamic nucleus region (STNr) in patients with Parkinson's disease (PD) as they made maximal voluntary grips. Relative to age-matched controls they had more rapid force decrement when contraction was meant to be sustained and prolonged release reaction time and slower rate of force offset when they were supposed to release the grip. These impairments were independent from medication status. Increased STNr power over 5-12 Hz (in the theta/alpha band) independently predicted better performance-reduced force decrement, shortened release reaction time and faster rate of force offset. In contrast, lower mean levels and progressive reduction of STNr power over 55-375 Hz (high gamma/high frequency) over the period when contraction was meant to be sustained were both strongly associated with greater force decrement over time. Higher power over 13-23 Hz (low beta) was associated with more rapid force decrement during the period when grip should have been sustained, and with a paradoxical shortening of the release reaction time. These observations suggest that STNr activities at 5-12 Hz and 55-375 Hz are necessary for optimal grip performance and that deficiencies of such activities lead to motor impairments. In contrast, increased levels of 13-25 Hz activity both promote force decrement and shorten the release reaction time, consistent with a role in antagonising (and terminating) voluntary movement. Frequency specific oscillatory activities in the STNr impact on motor performance from the beginning to the end of a voluntary grip. Copyright © 2012

Frequency specific activity in subthalamic nucleus correlates with hand bradykinesia in Parkinson's disease

PubMed Central

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

2013-01-01

Local field potential recordings made from the basal ganglia of patients undergoing deep brain stimulation have suggested that frequency specific activity is involved in determining the rate of force development and the peak force at the outset of a movement. However, the extent to which the basal ganglia might be involved in motor performance later on in a sustained contraction is less clear. We therefore recorded from the subthalamic nucleus region (STNr) in patients with Parkinson's disease (PD) as they made maximal voluntary grips. Relative to age-matched controls they had more rapid force decrement when contraction was meant to be sustained and prolonged release reaction time and slower rate of force offset when they were supposed to release the grip. These impairments were independent from medication status. Increased STNr power over 5–12 Hz (in the theta/alpha band) independently predicted better performance—reduced force decrement, shortened release reaction time and faster rate of force offset. In contrast, lower mean levels and progressive reduction of STNr power over 55–375 Hz (high gamma/high frequency) over the period when contraction was meant to be sustained were both strongly associated with greater force decrement over time. Higher power over 13–23 Hz (low beta) was associated with more rapid force decrement during the period when grip should have been sustained, and with a paradoxical shortening of the release reaction time. These observations suggest that STNr activities at 5–12 Hz and 55–375 Hz are necessary for optimal grip performance and that deficiencies of such activities lead to motor impairments. In contrast, increased levels of 13–25 Hz activity both promote force decrement and shorten the release reaction time, consistent with a role in antagonising (and terminating) voluntary movement. Frequency specific oscillatory activities in the STNr impact on motor performance from the beginning to the end of a voluntary grip

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.

Comparison of the effects of mirror therapy and electromyography-triggered neuromuscular stimulation on hand functions in stroke patients: a pilot study.

PubMed

Amasyali, Saliha Y; Yaliman, Ayşe

2016-12-01

To determine the effectiveness of mirror therapy and electromyography (EMG)-triggered neuromuscular stimulation on improvement of functions of the upper extremity in patients with subacute stroke in comparison with conventional therapy as well as to evaluate the advantage of each treatment over another, we conducted a prospective, randomized, and controlled trial involving 24 patients with ischemic stroke. The mean age and mean time since stroke of the patients were 58.79±11.49 years and 5.25±2.25 months. Patients were assigned randomly to a mirror therapy group (MT group, n=9), which consisted of therapy with a mirror box 5 days/week, 30 min/day, for 3 weeks, an electrostimulation group (ES group, n=7), which consisted of therapy with EMG-triggered stimulation (EMG-stim) of similar duration and frequency of treatment as the MT group, and a control group (n=8). All the groups received conventional physiotherapy for the same period as the MT group. Patients in the MT group practiced their therapy at home after supervised sessions. The Fugl-Meyer scores of the upper extremity, grip force, wrist extension, and Box and Block Test were evaluated at baseline, after treatment, and at 3 months after the treatment. All of these measures were evaluated by a blinded researcher. We found that there was no significant improvement in wrist extension range and grip force in control group. The MT and EMG-stim were effective in increasing the Fugl-Meyer motor scale for upper extremity (MT group: P<0.01), increasing wrist extension range, grip force, and hand dexterity determined by the Box and Block Test (MT group and ES group P<0.05). Furthermore, hand skills were increased significantly in the MT group compared with the ES group at the follow-up assessment (P<0.05). This pilot study suggested that MT was more efficient in improving motor performance than physiotherapy alone. Also, MT may be more useful in improving the hand skills compared with EMG-stim. We assume that this

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.

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.

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.

The efficacy of peloid therapy in management of hand osteoarthritis: a pilot study

NASA Astrophysics Data System (ADS)

Kasapoğlu Aksoy, Meliha; Altan, Lale; Eröksüz, Rıza; Metin Ökmen, Burcu

2017-12-01

Hand osteoarthritis (OA) is associated with pain, reduced grip strength, loss of range of motion (ROM), and joint stiffness, leading to impaired hand function and difficulty in performance of daily living activities. Mud bath therapy has been reported to play a primary role in the prevention and management of OA. Thus, we planned to conduct a study aimed at investigating the effects of peloid therapy on pain, functional state, grip strength, and the quality of life and performing a comparative analysis of the outcomes of peloid therapy. In this randomized, controlled, single-blind, pilot study, patients ( n = 33) underwent peloid therapy over 2 weeks, 5 sessions a week, for a total of 10 sessions and home exercise program in group 1. Patients in group 2 (control, n = 30) received only the same home exercise program as in group 1. Patients were evaluated just before, and 2 and 6 weeks after the start of the study with Visual Analogue Scale (VAS), Australian/Canadian Hand Osteoarthritis Index (AUSCAN), Health Assessment Questionnaire (HAQ), hand grip strength (HGS), and pinch strength (PS). Statistically significant improvements were observed in all parameters assessed at week 2 and week 6 in the group 1 ( p < 0.05). Statistically significant differences were observed in HGS scores in the group 2 at week 2 and in AUSCAN scores at week 6 ( p < 0.05). Intergroup comparisons of the scores revealed significant differences between the peloid therapy group and control group in VAS, HAQ, AUSCAN, HGS, and PS scores at week 2 and week 6 ( p < 0.05). This study demonstrates that peloid therapy might be an effective and confident treatment modality in the management of symptomatic osteoarthritis of the hand and may provide effective pain control and improvements in the hand functions, quality of life, and grip strength.

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

Performance of prioritized activities is not correlated with functional factors after grip reconstruction in tetraplegia.

PubMed

Wangdell, Johanna; Fridén, Jan

2011-06-01

To investigate the correlation between perceived performance in prioritized activities and physical conditions related to grip reconstruction. Retrospective clinical outcome study. Forty-seven individuals with tetraplegia were included in the study. Each participant underwent tendon transfer surgery in the hand between November 2002 and April 2009 and had a complete 1-year follow-up. Functional characteristics and performance data were collected from our database and medical records. Patients' perceived performances in prioritized activities were recorded using the Canadian Occupational Performance Measurement. Preoperative data included age at surgery, time since injury, severity of injury, sensibility and hand dominance. At 1-year follow-up, grip strength, key pinch strength, finger pulp-to-palm distance, distance between thumb and index finger and wrist flexion were measured. Correlation rank coefficient was used to test the possible relationship between physical data and activity performance. There were improvements in both functional factors and in rated performance of prioritized activities after surgery. There was no correlation between performance change and any of the physical functions, the factors known before surgery, or the functional outcome factors. No correlation exists between a single functional outcome parameter and the patients' perceived performance of their prioritized goals in reconstructive hand surgery in tetraplegia.

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

Functional and cosmetic outcome of single-digit ray amputation in hand.

PubMed

Bhat, A K; Acharya, A M; Narayanakurup, J K; Kumar, B; Nagpal, P S; Kamath, A

2017-12-01

To assess patient satisfaction, functional and cosmetic outcomes of single-digit ray amputation in hand and identify factors that might affect the outcome. Forty-five patients who underwent ray amputation were evaluated, 37 males and eight females whose mean age was 36.6 years ranging between 15 and 67 years. Twenty-eight patients had dominant hand involvement. Twenty-one patients underwent primary ray amputation, and 24 patients had secondary ray amputation. Eight out of the 23 patients with central digit injuries underwent transposition. Grip strength, pinch strength, tactile sensibility and functional evaluation using Result Assessment Scale (RAS) and DASH score were analysed. Cosmetic assessment was performed using visual analogue scale (VAS) for cosmesis. Median time of assessment after surgery was 20 months. Average loss of grip strength and pinch strength was found to be 43.3 and 33.6%, respectively. Average RAS score was 3.75. Median DASH score was 23.4. Eighty-three percentage of patients had excellent or good cosmesis on the VAS. Transposition causes significant increase in DASH scores for central digit ray amputations but was cosmetically superior. Middle finger ray amputation had the maximum loss of grip strength, and index finger ray amputation had greater loss of pinch strength. Affection of neighbouring digits caused greater grip and pinch loss, and a higher DASH score. Primary ray resection decreased the total disability and eliminated the costs of a second procedure. Following ray amputation, one can predict an approximate 43.3% loss of grip strength and 33.6% loss of pinch strength. The patients can be counselled regarding the expected time off from work, amount of disability and complications after a single-digit ray amputation. Majority of the patients can return to the same occupation after a period of dedicated hand therapy. Therapeutic, Level III.