Recovery of dynamic muscle function following isokinetic fatigue testing

This study was designed to evaluate recovery of dynamic muscle function following muscle fatigue produced by isokinetic testing. Sixteen physically active males (age = 29.2) performed fatigue and recovery tests on an isokinetic dynamometer (KIN-COM 500H). The fatigue test involved concentric contractions of the quadriceps femoris performed until force output fell below 50% MVC for 3 consecutive contractions. This test was repeated 3 times, with 1 minute rest between sets. Recovery of force output was measured during the following 8 minutes. Following post hoc analysis, subjects were grouped into 1 of 3 groups based on their time to recovery of 80% MCV; Recovery immediately following fatigue exercise (Group 1), between 3 and 6 minutes (Group 2), or no recovery during the 8 minute period (Group 3). Analysis revealed a significant decline in peak force between bouts of a three-bout fatigue test for Groups 2 and 3 (p < 0.001), and no decline in Group 1. There was a significant relationship between decline in force output and time to recovery. Thus, subjects developing a greater amount of muscle fatigue took longer to recover following this isokinetic test. It was concluded that an isokinetic fatigue test to 50% MVC, repeated 3 times, is an appropriate fatigue generating protocol for most active males; that recovery time following isokinetic fatigue exercise varies among active males; and recovery may be directly related to decline in force output between bouts of a three-bout fatigue test.