Maximizing Adaptations in Concurrent Training: An Umbrella Review of Meta-analyses.

Abstract

Concurrent training (CT), the combination of resistance training (RT) and endurance training (ET), is widely used in athletic and clinical settings. However, concerns about a potential interference effect have prompted ongoing debate regarding its impact on strength, power, hypertrophy, and aerobic capacity. A systematic search was conducted in PubMed, Web of Science, SPORTDiscus, and PsycNet following PRISMA guidelines and the four-eyes principle (28th February 2025). Main outcomes included aerobic capacity, muscle strength, power, and hypertrophy. Subgroup analyses were performed based on training modality, performance level, age, resistance training load, and endurance intensity. Seventeen meta-analyses comprising 144 individual studies and 1492 healthy participants were included. Umbrella data revealed comparable improvements in aerobic capacity for CT and ET. CT revealed significantly greater strength adaptations compared with ET (standardized mean difference [SMD] 0.59; p < 0.001). Compared with RT, CT significantly improved aerobic capacity (SMD 0.77; p = 0.02), while strength, power, and hypertrophy outcomes were comparable. No significant effects of training sequence were found; however, trends suggest performing RT before ET may favor strength (SMD 1.69; p < 0.001) and hypertrophy (SMD 0.83; p = 0.36) gains. CT improves both aerobic capacity and strength-related outcomes, making it a valuable strategy for comprehensive fitness development for recreationally trained individuals. While no relevant differences were found regarding the training sequence, performing RT before ET may enhance strength and hypertrophy adaptations. However, data from highly trained to elite athletes remain scarce and warrant further investigation. CRD42025646460.