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The objective of the study is to examine the effects of age and gender on finger coordination. Twelve young (24 +/- 8 yr; 6 men and 6 women) and 12 elderly (75 +/- 5 yr; 6 men and 6 women) subjects performed single-finger maximal contraction [maximal voluntary contraction (MVC)], four-finger MVC, and four-finger ramp force production tasks by pressing on(More)
Finger-pressing forces are produced by activation of the intrinsic hand muscles, which are finger specific, and the extrinsic muscles that connect to multiple fingers. We tested a hypothesis of greater weakening of intrinsic hand muscles with age and quantified associated indexes of finger interaction such as enslaving (force production by unintended(More)
We addressed a hypothesis that changes in indices of finger interaction during maximal force production (MVC) tasks are accompanied by changed coordination of fingers in multi-finger accurate force production tasks. To modify relative involvement of extrinsic and intrinsic hand muscles, the subjects produced force by pressing either at their distal(More)
Excitatory input to the alpha motor neuron pool from Ia afferents is enhanced by brief vibration, yet is depressed when vibration is applied for prolonged periods. The purpose of this article is to synthesize recent findings from several studies on the effects of prolonged vibration on motor unit activity and motor performance during maximal and submaximal(More)
Alternate muscle activity between synergist muscles has been demonstrated during low-level sustained contractions [< or =5% of maximal voluntary contraction (MVC) force]. To determine the functional significance of the alternate muscle activity, the association between the frequency of alternate muscle activity during a low-level sustained knee extension(More)
—This paper reports on the results of an experiment involving a wearable sensorimotor enhancer intended to improve tactile sensitivity in human fingertips. As briefly exposing tactile receptors to sub-sensory vibration is known to enhance tactile sensitivity thanks to a phenomenon called stochastic resonance (SR) in the somatosensory system, applying(More)
We used the uncontrolled manifold (UCM) approach to study the synergy formation during learning an unusual multi-finger task. The subjects produced accurate force ramps with challenging sets of four fingers (two per hand). We tested hypotheses on stabilization of the contributions of subsets of effectors to the task force ( F(TASK)) and to the moment in the(More)
To determine quantitatively the features of alternate muscle activity between knee extensor synergists during low-level prolonged contraction, a surface electromyogram (EMG) was recorded from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) in 11 subjects during isometric knee extension exercise at 2.5% of maximal voluntary(More)
The purpose of the study was to assess the effect of movement velocity on the relation between fluctuations in acceleration and the ability to achieve a target velocity during voluntary contractions performed by young (29.5 +/- 4.3 yr) and old (74.9 +/- 6.2 yr) adults. Subjects performed concentric and eccentric contractions with the first dorsal(More)
The study examined the hypothesis that altered synergistic activation of the knee extensors leads to cyclic modulation of the force fluctuations. To test this hypothesis, the force fluctuations were investigated during sustained knee extension at 2.5% of maximal voluntary contraction force for 60 min in 11 men. Surface electromyograms (EMG) were recorded(More)