Physical Adaptations to High‐Intensity Multimodal Training in Recreationally Active Adults: A Randomised Control Trial

High‐intensity multimodal training (HIMT), combines aerobic and resistance exercise within a single session, offering a time‐efficient training mode. However, the efficacy of HIMT for physical adaptations compared to other combined training models (e.g., inter‐session concurrent training [ISCT]) remains unclear. This two‐arm parallel randomised controlled trial examined the physical adaptations of 7 weeks of HIMT compared to a matched active control (ISCT) in recreationally active adults. The HIMT group completed 4 × 45‐min sessions/week integrating aerobic and resistance exercises. The ISCT group completed 2 × 45‐min resistance sessions/week and 2 × 45‐min aerobic sessions/week. Training intensity was prescribed at ≥ 7 RPE (CR‐10) with weekly volume and exercise selection matched across groups. Maximal strength, aerobic capacity, anthropometry and body composition were assessed pre and post‐intervention. Both HIMT ( n = 38) and ISCT ( n = 37) demonstrated small improvements in upper‐ and lower‐body strength, peak oxygen uptake and maximum work rate ( p < 0.05). Trivial but significant improvements were also observed in fat mass, body fat percentage, lean mass, waist circumference and waist‐to‐hip ratio ( p < 0.05). A modest group × time interaction favoured ISCT for reducing body fat percentage ( b = −0.628, 95% CI [−1.21 to −0.046], p = 0.035 and d = −0.082). Seven weeks of HIMT and ISCT improved muscular strength, aerobic fitness and body composition. Separating high‐intensity aerobic and resistance sessions across days may offer a small advantage for reducing relative body fat. Longer interventions may be needed for greater adaptations. Trial Registration ETH24‐9364, ACTRN12624000556549, Protocol: available on the Open Science Framework