Conference Agenda

Purpose: This study investigated changes in functional inter-limb asymmetry magnitude over 72 hours in adolescents following a muscle fatigue–inducing protocol.

Methods: Asymmetry magnitude in single-leg 10‑s hop jumps (SL10J), single‑leg countermovement jumps (SLCMJ), and single‑leg horizontal jumps (SLHJ) was assessed at baseline, immediately post-fatigue protocol, and 24, 48, and 72 hours post‑protocol in 7 female and 16 male adolescents aged 12–18 years. Segmental phase angle and ECW/TBW ratios derived from bioelectrical impedance analysis (BIA) were used as indicators of muscle damage, while muscle soreness was evaluated using a Visual Analog Scale (VAS).

Results: SL10J asymmetry magnitude significantly increased at 48 hours post‑exercise (p < 0.001), with no significant changes at other time points. SLCMJ and SLHJ asymmetry remained stable throughout testing (p = 0.468–0.714). BIA markers showed no significant evidence of muscle damage, although VAS scores indicated a significant rise in muscle soreness peaking at 48 hours (p < 0.05). Kappa coefficients revealed slight to moderate task‑specific agreement (κ = −0.123–0.493) and slight to substantial time‑specific agreement (κ = −0.137– 0.732), with the greatest consistency observed between 24 and 48 hours for both SLCMJ and SL10J.

Conclusion: Asymmetry magnitude increased significantly only for the SL10J at 48 h post‑exercise, suggesting an asymmetrical recovery from exercise‑induced fatigue between limbs and resulting in temporary shifts in inter‑limb asymmetry. Since asymmetries may affect sport performance and injury risk, a task‑ and time‑specific monitoring approach that accounts for athletes’ fatigue levels is recommended when assessing (recreational) athletes.