Effects of local muscular fatigue due to isotonic and isometric exercise upon fractionated reaction time components.

Fractionated RT for a right knee-extension task was assessed on eight male and eight female Ss over eight treatment days. Following four consecutive days of 75 RT trials /day to insure stabilized strength and RT components, Ss were administered two days of bench stepping and two days of isometric exercise designed to induce muscular fatigue of the knee extensors. Significant strength decrements of up to 24% were induced by both the isotonic (bench stepping) and isometric exercise treatment conditions but no changes were observed in fractionated RT components. The results would seem to indicate that performance differences in fine-versus gross-motor skill tasks due to fatigue need to be more carefully examined.