Postcontraction errors in isometric force control.
Subjects learned to produce brief isometric force pulses that were 10% of their maximal voluntary contraction (MVC) force. Subjects became proficient at performing sets of 10 pulses within boundaries of 8-12% MVC, with visual feedback and without (kinesthetic sense). In both the control (Con, n = 10) and experimental (Exp, n = 20) groups, subjects performed two sets of 10 kinesthetically guided pulses. Subjects then either performed a 10-s MVC (Exp) or remained at rest (Con) between sets. Following the MVC, Exp subjects had force errors of +30%, whereas performance was maintained in Con. There was evidence for both muscular and neural contributions to these errors. Postactivation potentiation resulted in a 40% gain in muscle contractility (p = .003), and there was a 26% increase in the neural stimulation of muscle (p = .014). Multiple regression indicated that the change in neural input had a stronger relationship with force errors than the increased contractility.
Knight
Christopher A
CA
University of Delaware Human Performance Laboratory, Newark, DE, USA.
Marmon
Adam R
AR
Poojari
Dhiraj H
DH
D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007858:Learning; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000294:innervation*; D013997:Time Factors