Sex-specific dose-response effects of a 24-week supervised concurrent exercise intervention on cardiorespiratory fitness and muscular strength in young adults: The ACTIBATE randomized controlled trial

Concurrent training has been postulated as an appropriate time-efficient strategy to improve physical fitness, yet whether the exercise-induced adaptations are similar in men and women is unknown. An unblinded randomized controlled trial was conducted to investigate sex-specific dose-response effects of a 24-week supervised concurrent exercise training program on cardiorespiratory fitness and muscular strength in young adults. One hundred and forty-four sedentary adults aged 18-25 years were assigned to either (i) a control group (n = 54), (ii) a moderate intensity exercise group (MOD-EX, n = 46), or (iii) a vigorous intensity exercise group (VIG-EX, n = 44) by unrestricted randomization. Cardiorespiratory fitness (VO2max), hand grip strength, and one-repetition maximum of leg press and bench press were evaluated at baseline and after the intervention. A total of 102 participants finished the intervention (Control, n = 36; 52% women, MOD-EX, n = 37; 70% women, and VIG-EX, n = 36; 72% women). In men, VO2max significantly increased in the MOD-EX (similar to 8%) compared with the control group and in the VIG-EX group after the intervention (similar to 6.5%). In women, VO2max increased in the MOD-EX and VIG-EX groups (similar to 5.5%) compared with the control group after the intervention. There was a significant increment of leg press in the MOD-EX (similar to 15.5%) and VIG-EX (similar to 18%) groups compared with the control group (similar to 1%) in women. A 24-week supervised concurrent exercise was effective at improving cardiorespiratory fitness and lower body limbs muscular strength in young women-independently of the predetermined intensity-while only at moderate intensity improved cardiorespiratory fitness in men.