Effects of Maximal vs. Submaximal Isometric Fatiguing Exercise on Subsequent Submaximal Exercise Performance

Miller, WM, Ye, X, and Jeon, S. Effects of maximal vs. submaximal isometric fatiguing exercise on subsequent submaximal exercise performance. J Strength Cond Res 34(7): 1875-1883, 2020-Exercise-induced muscle fatigue directly influences subsequent exercise performance. Thus, we examined task failure times for submaximal intermittent fatiguing isometric contractions performed after a bout of sustained maximal vs. submaximal isometric fatiguing contractions with the dominant elbow flexors. Twenty physically active individuals 8 men (mean ± SD = 21.4 ± 1.8 years; 80.9 ± 12.5 kg; 180 ± 6.4 cm) and 12 women (mean ± SD = 21.4 ± 2.7; 66.8 ± 15.6 kg; 165.7 ± 7.1 cm) participated in a 3-visit randomized cross-over study. Visit 1 included familiarization, and 2 and 3 were randomized for sustained maximal (until force was below 50% of the maximal force value) or submaximal conditions (50% of maximal force until task failure), followed by submaximal intermittent isometric contractions to task failure. Surface electromyography was recorded through the biceps brachii during all fatiguing contractions. Task failure time was significantly shorter for the maximal compared with submaximal condition, and no significant difference in sex or condition was found for the subsequent fatiguing condition. Electromyography amplitude significantly increased in the submaximal intermittent isometric contractions from prefatigue and first and final postfatigue with no condition or sex differences. Electromyography mean frequency significantly decreased from prefatigue and first and final postfatigue for both sexes, with no condition or sex differences. With both maximal and submaximal exercises inducing the same level of force deficit, our results suggested that both exercises might have imposed a similar burden on the neuromuscular system, thereby not providing differential effects on the subsequent submaximal exercise performance.