The role of physiological tremor in isometric force control
Novak, Thomas S
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The purpose of this study was to investigate the influence of physiological tremor on isometric force scaling and hand dominance in relation to variability of isometric force control. Subjects were instructed to match a target line and minimize variability in a uni-manual isometric finger abduction task at 5%, 25%, 45%, 65%, and 85% of their maximal voluntary contraction (MVC). The experimental protocol was performed in separate blocks of the left and right hands, respectively. Physiological tremor correspondent to oscillation in the 8-12 Hz frequency band was enhanced with neural drive across all force conditions. This enhancement correlated directly to changes in both performance (RMSE) and structural variability (Sample Entropy) of the force signal. No significant findings were found between the dominant and non-dominant hands. The findings provide evidence that physiological tremor has a direct influence on the dispersion and structure of the variability of isometric force control.