Abstract
The aim of this study was to test the hypothesis that intraindividual variability in isokinetic knee extension/flexion relates positively to muscle fatigue, i.e., the less the muscle fatigue during exercise, the greater is the variability of torque fluctuation. Twelve healthy males performed 100 continuous knee extensions and flexions with maximal intensity at 180°/s. The main findings were: 1) the knee extension muscle exhibited more fatigue and less intraindividual variability than the knee flexion muscles; 2) intraindividual variability in knee extension (SD for torque fluctuation in 100 repetitions) relates closely to fatigue. We conclude that intraindividual variability in isokinetic knee-extension torque relates inversely to muscle fatigue.