Multi-directional strength and force envelope of the index finger

Li, Zong-Ming; Pfaeffle, H. James; Sotereanos, Dean G.; Goitz, Robert J.; Woo, Savio L.-Y.

doi:10.1016/s0268-0033(03)00178-5

Cited by 43 publications

(46 citation statements)

References 25 publications

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“…Since multi-finger adduction is a grasping (as opposed to releasing) pattern it may have evolved to be stronger than abduction in the same way that flexion is stronger than extension (e.g. Li et al 2003, Cruz et al 2005). …”

Section: Discussion Strengthmentioning

confidence: 99%

“…Similar to other MVC experiments (e.g. Li et al 2003) subjects were free to choose the manner in which they produced MVC; they tended to either ramp slowly to MVC or to generate MVC in a brief thrust. Post hoc analysis revealed that maximum force was not dependent on the time taken to generate that force (linear regression yielded a correlation coefficient of r 2 = 0.0025).…”

Section: Methods Designmentioning

confidence: 99%

“…Buschbacher 1997), measure individual finger strength separately (e.g. Matheson et al 1970;Schreuders et al 2000;Li et al 2003), or examine only kinematic quality (e.g. Sandqvist and Eklund 2000).…”

Section: Introductionmentioning

confidence: 99%

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Multifinger Ab- and Adduction Strength and Coordination

Pataky

Latash

Zatsiorsky

2008

Journal of Hand Therapy

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Simultaneous ab-and adduction of the fingers (finger spreading and finger squeezing) are fundamental to many prehension tasks. This is the first study to describe all finger forces during multi-finger ab-/adduction. Twenty one healthy subjects (12 female) produced maximal ab-/ adduction efforts against a stationary apparatus equipped with four independent multi-axis force transducers. Total force was computed as the sum of the absolute values of individual finger forces. The males were significantly stronger than the females, and adduction (squeezing) forces (42.4 N) were significantly greater than abduction forces (32.6 N). The relative contributions of individual fingers to the total force were consistent across the genders, implying that strength did not affect coordination. Ab-/adduction were coordinated symmetrically and multi-finger performance was not predictable from single finger strengths. The latter finding, in particular, indicates that multi-finger spreading/squeezing force measurements can provide information about hand function that cannot be derived from other tests.

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Section: Discussion Strengthmentioning

confidence: 99%

Section: Methods Designmentioning

confidence: 99%

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Multifinger Ab- and Adduction Strength and Coordination

Pataky

Latash

Zatsiorsky

2008

Journal of Hand Therapy

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“…The patterns of muscle activation were subject-independent and the activity levels scaled with the force magnitude. Distribution of maximal index-fingertip force in all directions was also studied by Li et al (2003).…”

Section: Introductionmentioning

confidence: 99%

Control of finger force direction in the flexion-extension plane

2004

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We have examined the interaction among individual finger forces in tasks that required the production of the total force by a subset of fingers in a particular direction in the flexion-extension plane. Nine subjects produced fingertip forces in a prescribed direction with a maximum voluntary contraction (MVC) effort and held the peak force for two seconds. Six finger combinations were tested, four single-finger tasks-Index (I), Middle (M), Ring (R) and Little (L)-one two-digit task (IM), and one four-digit task (IMRL). The subjects were asked to generate the finger forces in two directions, 0° (perpendicular to the surface of the transducer) and 15° toward the palm. In all task conditions, there were two experimental sessions, with and without visual feedback on the task force vector. The main findings were:1. The target direction significantly affected the constant error (CE) but not the variable error (VE) while removal of the feedback resulted in an increase in VE. 2.The direction of the forces produced by fingers that were not explicitly required to produce force (enslaved fingers) depended on the target direction. 3.In multi-finger tasks, the individual fingers produced force in directions that could differ significantly from the target direction, while the resultant force pointed in the target direction. There was a negative co-variation among the deviations of the directions of the individual finger forces from the target direction. If a finger force vector deviated from the target, another finger force vector was likely to deviate in the opposite direction. We conclude that a multi-finger synergy is involved in the control of the finger force direction.

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“…Physiologically, this allows the finger to produce the maximum palmar force when the finger is flexed and adducted. A study by Li et al [30] in which the finger strength in various finger configurations was measured also concluded that the finger strength is highest when MCP joint is adducted and flexed. Our results have proven that variations in moment arms of the finger muscles might have played a significant role in achieving configuration-dependent variations in finger strength.…”

Section: Implications For Force and Velocity Controlmentioning

confidence: 99%

Acquiring Variable Moment Arms for Index Finger Using a Robotic Testbed

Deshpande

Balasubramanian

et al. 2010

IEEE Trans. Biomed. Eng.

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Abstract-Human level of dexterity has not been duplicated in a robotic form to date. Dexterity is achieved in part due to the biomechanical structure of the human body and in part due to the neural control of movement. We have developed an anatomically correct testbed (ACT) hand to investigate the importance and behavioral consequences of anatomical features and neural control strategies of the human hand. One of the critical aspects of understanding dexterity is the analysis of the relationships between the hand muscle movements and joint movements, defined by the moment arms of the muscles. It is known that the moment arms for the hand muscles are configuration-dependent and vary substantially with change in posture. This paper presents a methodology for determining continuous variations in the moment arms with respect to multiple joints moving simultaneously. To determine variations in the moment arms of the ACT hand index finger muscles, we employed a nonparametric regression method called Gaussian processes (GPs). GPs give a functional mapping between the joint angles and muscle excursions, and the gradients of these mappings are the muscle moment arms. We compared the moment arm relationships of the ACT hand with those determined from the available cadaver data. We present the implications of the determination of variable moment arms toward understanding of the biomechanical properties of the human hand and for the neuromuscular control for the ACT hand index finger movements.

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Multi-directional strength and force envelope of the index finger

Cited by 43 publications

References 25 publications

Multifinger Ab- and Adduction Strength and Coordination

Multifinger Ab- and Adduction Strength and Coordination

Control of finger force direction in the flexion-extension plane

Acquiring Variable Moment Arms for Index Finger Using a Robotic Testbed

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