Sprint interval and moderate-intensity cycling training differentially affect adiposity and aerobic capacity in overweight young-adult women.

The purpose of the study was to examine the effects of sprint interval training (SIT) and moderate-intensity continuous cycle training (MICT), with equal estimated energy expenditure during training on body composition and aerobic capacity. Body composition measured via dual-energy X-ray absorptiometry and aerobic capacity were assessed following 6 weeks of training in previously inactive overweight/obese young women (n = 52; age, 20.4 ± 1.5 years; body mass index, 30.3 ± 4.5 kg·m-2, 67.3% white). Training was performed in a group-exercise format that mimicked cycling classes offered by commercial fitness facilities, and included 3 weekly sessions of either 30-s "all-out" sprints followed by 4 min of active recovery (SIT), or continuous cycling at 60%-70% heart rate reserve to expend a similar amount of energy. Participants were randomized to SIT or MICT, attended a similar number of sessions (15.0 ± 1.5 sessions vs. 15.8 ± 1.9 sessions, P = 0.097) and expended a similar amount of energy (541.8 ± 104.6 kJ·session-1 vs. 553.5 ± 138.1 kJ·session-1, P = 0.250). Without significant changes in body mass (P > 0.05), greater relative reductions occurred in SIT than in MICT in total fat mass (3.6% ± 5.6% vs. 0.6% ± 3.9%, P = 0.007), and android fat mass (6.6% ± 6.9% vs. 0.7% ± 6.5%, P = 0.002). Aerobic capacity (mL·kg-1·min-1) increased significantly following both interventions (P < 0.05), but the relative increase was 2-fold greater in SIT than in MICT (14.09% ± 10.31% vs. 7.06% ± 7.81%, P < 0.001). In conclusion, sprint-interval cycling reduces adiposity and increases aerobic capacity more than continuous moderate-intensity cycling of equal estimated energy expenditure in overweight/obese young women.