POOR FORCE CONTROL PERFORMANCE AND UNVARIED EMG PATTERN AFTER AGONIST MUSCLE FATIGUE IN HUMANS

Abstract

Ballistic and accurately control of a targeted fast contraction relies on phasic activations of the agonist and antagonist muscles. The purpose of the study was to investigate the effect of tibialis anterior (TA) fatigue on the systematic bias and the consistence of the net dorsiflexion torque generation and the controlling pattern of the agonist-antagonist muscles. Ten subjects were tested twice with a week apart. Fast and slow dorsiflexion at 40%-MVG were measured before and after fatigue of the TA by voluntary isometric dorsiflexions. The EMG of the TA and soleus (Sol) were recorded. The results revealed that more post-fatigue increment of the systematic error was in the fast dorsiflexions, random error increment were similar in both speeds of isometric dorsiflexions, the cocontraction ratio increased after fatigue only in the slow dorsiflexions. Our results suggested that precision of the fast targeted isometric contractions was reduced after fatigue because of unvaried agonist-antagonist control strategy.