Effects of Complex and Contrast Training on Lower Limb Explosive Power and Eccentric Strength in Elite Male Track and Field Athletes: A 24-Week Randomized Trial

Xu, Z, Lin, Y, Zhang, F, Li, Q, Yu, L, Lin, M, Ning, F, and Wang, X. Effects of complex and contrast training on lower limb explosive power and eccentric strength in elite male track and field athletes: A 24-week randomized trial. J Strength Cond Res XX(X): 000-000, 2026-This 24-week randomized controlled trial compared the effects of complex training (postactivation potentiation) and contrast training (postactivation performance enhancement) on lower-limb explosive power (jump height, push-off power) and eccentric strength (drop height, countermovement impulse) in track and field athletes, while assessing arm swing's role in kinetic chain coordination. Forty-five national-level track and field athletes were randomized into complex training, contrast training, or control groups. Kinetic data were collected using a 3-dimensional force plate. Repeated-measures ANOVA and multivariate regression (ΔR2) analyzed intervention effects under arm-swing and non-arm-swing conditions, with cross-group comparisons. Cross-group analyses showed complex training significantly outperformed contrast training and control in jump height with arm swing (+30.9%, 0.55-0.72 m, P < 0.001 vs. +17.1%, 0.58-0.68 m, P = 0.012 vs. +7.7%, 0.52-0.56 m, P = 0.231) and drop height (+30.4%, 0.46-0.60 m, P < 0.001 vs. +15.2%, 0.46-0.53 m, P = 0.031 vs. +5.2%, 0.46-0.48 m, P = 0.672). Contrast training excelled in reducing push-off time without arm swing (-6.1%, 0.214-0.201 seconds, P = 0.002 vs. +1.2%, P = 0.721 vs. +0.8%, P = 0.821) and increasing push-off power (+17.1%, 122.23-129.02 W·kg-1, P = 0.009 vs. +9.8%, P = 0.041 vs. +2.3%, P = 0.762). Arm swing enhanced eccentric-concentric efficiency, with complex training showing stronger correlations (push-off power vs. jump height: r = 0.527, P < 0.001). Eccentric strength explained 43.1% of jump height variance (R2 = 0.431, P < 0.001). Complex training enhances elastic energy storage, whereas contrast training improves neural coordination. The results support tailored training based on eccentric strength and sport-specific needs.