Objectives: This study examined how different sequences of concurrent training impacted physical activity (PA), body composition, and physical fitness in young obese males. We also investigated whether the effectiveness of these interventions in reducing body fat percentage (BF%) was influenced by PA levels.

Methods: A 12-week randomized controlled trial involving a cohort of 45 obese young males (mean age: 22.42 ± 1.96 years, mean BMI: 29.78 ± 3.37) was conducted. Participants were randomly assigned to three groups: the CRE group (Resistance Training (RT) followed by Endurance Training (ET)), the CER group (ET followed by RT), and the control group (Con). The training sessions were held three times a week. Measurements, including PA level, body composition, bone density, VO2max, and muscle strength, were assessed before and after the intervention.

Results: Compared to those at baseline, following the intervention, both the CRE and CER groups showed significant improvements in various parameters, including PA level, body composition, bone density, VO_2max, and muscle strength (p < 0.05), whereas no significant changes were observed in the Con group (p > 0.05). Specifically, the CRE group demonstrated remarkable progress, as evidenced by an increase in MVPA level (η² _p = 0.37, p < 0.001), a reduction in fat mass (η² _p = 0.28, p < 0.001), BF% (η² _p = 0.28, p < 0.001), android fat (%) (η² _p = 0.21, p < 0.001), gynoid fat (%) (η² _p = 0.30, p < 0.001), and various physical fitness indices, such as maximum strength (η² _p = 0.20, p = 0.008), explosive strength (η² _p = 0.38, p < 0.001), and muscular endurance (η² _p = 0.55, p < 0.001), surpassing the improvements observed in the CER and Con groups. Changes in PA levels during the intervention influence the efficacy of CT in reducing BF%.

Conclusion: CT, particularly when RT precedes ET, had the potential to improve PA levels, overall physical fitness, body composition, and bone health in obese young males. Moreover, changes in PA levels during the intervention impacted the effectiveness of CT in reducing BF%.

Trial registration: ChiCTR, ChiCTR2200063892.

Keywords: Body composition; Concurrent training; Obesity; Young males.

© 2025 The Society of Chinese Scholars on Exercise Physiology and Fitness. Published by Elsevier (Singapore) Pte Ltd.