Evaluation of a method for bimanual testing coordination of hand grip and load forces under isometric conditions

Jarić, Slobodan; Knight, Christopher A.; Collins, Jeffrey J.; Marwaha, Rahul

doi:10.1016/j.jelekin.2005.03.003

Cited by 32 publications

(41 citation statements)

References 23 publications

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Section: Discussionsupporting

confidence: 93%

“…Regarding task performance, a deterioration of task performance in MS patients was noticed in all three tasks. This finding is in line with our previous results (Jaric, Knight, Collins, & Marwaha, 2005;Marwaha, Hall, Knight, & Jaric, 2006) and generally suggests that the ability to exert an accurate pattern of external forces could be one of the first signs of functional impairment of the hands associated with the progress of the disease.Force coordination was assessed through G/L ratio, force coupling, and G modulation. When compared with healthy controls, MS patients showed a higher G/L ratio in all three tasks This result is in line with findings obtained from other neural pathologies (see the introduction for details) and suggests that, in addition to inaccurate L pattern, an elevated G/L ratio could also be an early sign of hand function impairment in MS.…”

supporting

confidence: 93%

“…First, we tested simple manipulation tasks that closely resemble everyday activities, such as lifting and holding an object or exerting a force against a fixed object or external support. Second, most of the derived variables have already demonstrated either a moderate or high reliability (Jaric, Knight, Collins, & Marwaha, 2005). Therefore, one could conclude that the study provided both valid and reliable data regarding hand function in the tested subjects.…”

Section: Discussionmentioning

confidence: 71%

“…About 10% of the maximum pinch G of the weaker hand served as the instructed peak L in the main experiment. According to our previous findings, this level was well below the one that could cause fatigue over the course of the experiment (Jaric, Knight, Collins, & Marwaha, 2005). As a result, the maximum level of the prescribed L was participant specific and ranged from 4 to 10 N. Thereafter, the tasks were explained and demonstrated, and the participants practiced the tasks over approximately 15 min.…”

Section: Experimental Device and Proceduresmentioning

confidence: 85%

“…If the results support the hypotheses, the findings would not only reveal the specific aspects of impairment of hand function in mildly impaired MS patients, but also speak in favor of the applied approach as a methodology sensitive enough to detect a mild level of impairment of hand function in MS. The latter could be of particular importance due to a general lack of objective quantitative methods for assessment of hand function in MS, as well as in other neurological diseases (Jaric, Knight, Collins, & Marwaha, 2005). …”

mentioning

confidence: 99%

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Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Krishnan¹,

Freitas²,

Jarić³

2008

Motor Control

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We investigated hand function in mildly involved Multiple Sclerosis (MS) patients (N = 16; EDSS 1−5, 9-hole peg test 14−32 s) during static and dynamic manipulation tasks using an instrumented device. When compared with healthy controls (N = 16), the patients revealed impaired task performance regarding their ability to exert prescribed patterns of load force (L; force acting tangentially at the digits-object surface). Regarding the coordination of grip force (G; normal component) and L, the data only revealed elevated G/L ratio, although both the G and L coupling (maximum correlation coefficients and the time lags between them), and G modulation (gain and offset of G with respect to L) remained comparable in the two groups. Finally, most of the data suggested no MS-specific effects of switching from uni-to bimanual tasks, from available visual feedback to deprived feedback conditions. We conclude that the deterioration in the ability for precise control of external forces and overgripping could precede the decoupling of G and L and decreased G modulation in early phases of the disease. The results also suggest that the applied methodology could be sensitive enough to detect mild levels of impairment of hand function in MS and, possibly, other neurological diseases.Keywords hand function; grip; load; force coordination; coupling; task performanceThe main hand function is to grasp and manipulate objects and external supports. This function is essential for everyday life, and, consequently, an impaired hand function (e.g., associated with neurological diseases or injuries) could be an important obstacle to living an independent life. When an externally fixed (e.g., a handle providing external support) or a free-moving object (a cup of coffee, or a tool) is held with the opposing tips of the thumb and fingers, a load force (L) is applied tangentially to the surfaces in contact to move the object or exert a reaction force. The slippage of the object is countered by friction force originating from grip force (G) acting normally to the surface. A consistent finding throughout the literature has been that the changes in G and L appear to be highly coordinated. This coordination is based not only on an ability of the neural controlling mechanisms to assess the skin-object friction coefficient and, based on it, apply a relatively low safety margin [i.e., G slightly higher than necessary to prevent slippage; (Johansson & Westling, 1984)], but also to modulate G in parallel with L without any considerable time delays between them [i.e., using anticipatory mechanisms (Flanagan & Wing, 1995. The result appears to be a stable and relatively low grip-toload (G/L) ratio (Johansson, 1998), high coupling of G and L (as assessed by both high correlation coefficient and virtually no time lags between them [Blakemore, Goodbody, & Wolpert, 1998;Flanagan & Tresilian, 1994]), and a high level of modulation of G with respect to changes in L [i.e., high gain and low offset assessed through the slope and intercept, respectively, o...

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Section: Discussionsupporting

confidence: 93%

supporting

confidence: 93%

Section: Discussionmentioning

confidence: 71%

Section: Experimental Device and Proceduresmentioning

confidence: 85%

mentioning

confidence: 99%

See 3 more Smart Citations

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Krishnan¹,

Freitas²,

Jarić³

2008

Motor Control

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Force coordination in static manipulation tasks: effects of the change in direction and handedness

2007

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A number of studies have demonstrated high coordination of the hand grip force (GF; normal component of force acting at the digits-object contact area) and load force (LF; tangential component) in a variety of manipulation tasks. The aim of the study was to explore the mainly neglected effect of the change in LF direction and the effect of handedness on GF and LF coordination in bimanual manipulation task. Subjects (N = 14) exerted a bimanual sinusoidal LF pattern against externally fixed handles in trials that gradually changed from unidirectional (LF exerted only in one direction) to fully bidirectional (equal LF peaks in two opposite directions). Despite the gradual change of LF, unidirectional trials demonstrated high indices of force coordination, while in all bidirectional trials, no matter how low and brief LF exertion was in the opposite direction, all indices of GF and LF coordination deteriorated to a considerably lower level. The non-dominant hand demonstrated both a higher directional accuracy of exerting LF and higher GF modulation than the dominant one. We concluded that manipulation tasks performed in a single and two alternating directions may be based on partly distinctive neural control mechanisms, as well as that a switching of muscle synergies required in bidirectional tasks could play a role in the observed phenomenon. Regarding the effect of hand dominance, the recorded advantage of the non-dominant hand could be considered as an addition to the current views of the non-dominant arm/hemisphere specialization in controlling limb position.

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

Freitas

Jarić

2009

Exp Brain Res

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

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Evaluation of a method for bimanual testing coordination of hand grip and load forces under isometric conditions

Cited by 32 publications

References 23 publications

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Impaired Object Manipulation in Mildly Involved Individuals with Multiple Sclerosis

Force coordination in static manipulation tasks: effects of the change in direction and handedness

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

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