Does a Muscle Fatigue-Inducing Protocol Alter the Magnitude of Jump Inter-Limb Asymmetry in Healthy Adolescents?

This study examined changes in jump asymmetry in adolescents over a 72-hour period following a muscle fatigue-inducing protocol. Single-leg 10-s hop jump (SL10J), single-leg countermovement jump (SLCMJ), and single-leg horizontal jump (SLHJ) asymmetries were measured at baseline, immediately post-exercise, and at 24, 48, and 72 h post-exercise in 7 female and 16 male adolescents aged 12-18 years. The bioelectrical impedance analysis derived segmental phase angle and ECW/TBW were used as indicators of muscle damage for each leg, while the Visual Analog Scale (VAS) assessed muscle soreness and the bilateral countermovement jump (BCMJ) and the bilateral horizontal jump (BHJ) indicated changes in absolute jump performance. A significant increase in SL10J asymmetry was observed 48 hours post-exercise (p < 0.001), while no significant changes were detected immediately post-exercise or at 24 and 72 h. No significant changes were found in SLCMJ or SLHJ asymmetry at any time point. BIA did not indicate significant muscle damage, though a significant increase in muscle soreness (VAS), peaking at 48 h post-exercise, was recorded. The kappa values indicated slight to moderate agreement for task specificity and slight to substantial agreement for time specificity, with the highest consistency between 24 and 48 h post-exercise for both the SLCMJ and the SL10J. To conclude, asymmetry significantly increased only for the SL10J at 48 h post-exercise, suggesting that repeated jump tests may be more sensitive to fatigue-induced asymmetry than single-jump tests. The substantial kappa values at 24 and 48 h highlight the potential to offer a more robust assessment of asymmetry when recovering from a fatigue-inducing event.