Dominant Leg Continuous Unilateral Hopping Impairs Contralateral Leg But Not Upper Body Explosive Performance

Many non-local muscle fatigue studies utilize continuous isometric contractions to induce unilateral fatigue and assess contralateral limb strength and endurance. The present study aimed to investigate the effects of dynamic unilateral lower-limb fatigue on contralateral lower-limb and upper-body explosive performance. Eighteen healthy adults (30.3 ± 9.3 years) completed sessions involving continuous exercise performed to induce fatigue (1 min of unilateral hopping), intermittent exercise performed to induce fatigue (two 30-s bouts of unilateral hopping), and a non-active control. Explosive performance was measured before the intervention and at 1, 5, and 10 min post-intervention using repeated single-leg hops (10 repetitions) and rebound push-ups (5 repetitions). Significant interactions showed that contralateral hop height (p = 0.048), reactive strength index (p = 0.003), and lower-limb power (p < 0.001) were significantly reduced 1 min post-exercise after unilateral continuous hopping. Hop height and power remained significantly lower at 5 min post-exercise (p = 0.03 and p = 0.008, respectively). In contrast, intermittent hopping did not induce significant contralateral lower-limb impairments but resulted in higher upper-body ratings of perceived exertion 1 min post-exercise compared with pre-exercise (p = 0.017) and 5 min post-exercise (p = 0.008). In conclusion, continuous unilateral hopping transiently impairs contralateral lower-limb explosive performance, whereas upper-body explosive performance remained unaffected. Intermittent hopping increases upper-body perceived exertion without affecting contralateral performance. These findings highlight the task-specific and structure-dependent nature of non-local fatigue.