Athletic Performance after Complex Training Compared with Traditional Strength Training

Effects of≥4‑week complex training in trained/developmental athletes (three or more times/wk, local competition) are unclear. This review addressed this gap. Five databases were searched (updated June 2025) for randomized controlled trials (RCTs) comparing complex training with traditional strength training on jump, agility, and sprint. Three‑level meta‑analyses with moderation and Grading of Recommendations Assessment, Development, and Evaluation certainty assessment were used. Seventy‑five studies were included. Complex training produced moderate‑to‑large improvements in the countermovement jump (62 studies; effect size=0.58, p<0.01, I 2=33.99%), squat jump (23; effect size=0.77, p<0.01, I 2=68.59%), agility (29; effect size=− 1.05, p<0.01, I 2=63.97%; negative=faster), and sprint (50; effect size=− 0.65, p<0.05, I 2=56.04%). Larger effects were observed greater effects were found for technical/composite athletes and younger athletes. Dose–response meta‑regression revealed non‑linear associations. Peak countermovement jump effects were greatest at 1 rep minimum (standardized mean difference=1.69, 95% confidence interval: [0.56, 2.81]) and 14 repetitions maximum (standardized mean difference=1.36, 95% confidence interval: [0.34, 2.38]). The largest agility and sprint improvements occurred at six sets (agility: standardized mean difference=− 1.60, 95% confidence interval: I [− 2.37,−0.83]; sprint: standardized mean difference=− 1.28, 95% confidence interval: [− 2.01,−0.57]) and 12 reps (sprint min.rep: standardized mean difference=− 1.33, 95% confidence interval: [− 2.26,−0.40]), indicating attenuation at insufficient/excessive loads. Certainty is moderate. Complex training effectively improves athletic performance, moderated by athlete characteristics and optimized by outcome‑specific dosing. Complex training is recommended to enhance key athletic qualities in higher-level athletes. Prescriptions are individualized, with higher volumes for technical-sport and younger athletes. Optimal dose ranges (weeks, sets, and reps) for jumps, agility, and sprint offer evidence‑based guidelines for program design.