Effect of Moderate Versus Vigorous Exercise Intensity on Body Composition in Young Untrained Adults: The Activating Brown Adipose Tissue Through Exercise (ACTIBATE) Randomized Controlled Trial

The present study aimed to investigate the effect of a 24-week aerobic + resistance training programs at moderate versus vigorous intensity on body composition, and the persistence of the changes after a 10-month free-living period, in young untrained adults. This report is based on a secondary analysis from the activating brown adipose tissue through exercise (ACTIBATE) single-center unblinded randomized controlled trial. A total of 144 young adults (65.6% women) aged 18-25 years were randomly allocated to three different groups: (a) aerobic + resistance exercise training program based on the international physical activity recommendations at vigorous intensity (Ex-Vigorous group), (b) at moderate intensity (Ex-Moderate group), and (c) control group (no exercise). Body composition outcomes were determined by a dual-energy X-ray absorptiometry scanner. Both Ex-Vigorous and Ex-Moderate decreased body weight, fat mass, and visceral adipose tissue mass in a similar manner (all p < .04). After a 10-month free-living period, these parameters returned to baseline levels in both exercise groups (all ps < .03). No differences between the exercise groups and the control group were noted in lean mass changes (all ps > .1). A 24-week aerobic + resistance training intervention based on the international physical activity recommendations was enough to improve body weight, fat mass, and visceral adipose tissue mass in untrained young adults, independently of the exercise intensity (moderate vs. vigorous).

Automated summary

This study investigated the effect of moderate versus vigorous intensity aerobic + resistance training programs on body composition, and the persistence of the changes after a free-living period. The results showed that both intensity levels of exercise training were effective in reducing body weight, fat mass, and visceral adipose tissue mass. However, these changes returned to baseline levels after the free-living period. There were no significant differences in lean mass changes between the exercise groups and the control group.