Effect of exercise intensity on post-exercise substrate utilisation

Abstract

A negative or neutral energy balance (EB) is essential for weight loss or maintenance, and post exercise (EE) energy expenditure (EE) is a significant contributor to total EE and therefore EB. Post-exercise (PE) substrate utilisation is also important to health, therefore we examined the effects of exercise intensity on the quantity and direction of PE EE in healthy men (n=5; age=20 ±1yr) and women (n=5; age 21±2yr). One continuous (30 mins @ 70% VO2max) and one interval (4x4min @85% VO2max separated with 3min active recovery @ 50% VO2max) exercise sessions that were match for total EE were performed and respiratory gas analysis was take for 1hr of PE recovery. Average HR and VO2 were not significantly (p>0.05) different during exercise and peak HR and VO2 were significantly (p<0.05) higher during the interval session compared to the continuous session. RER was significantly (p<0.05) lower during PE recovery after interval compared to continuous exercise (0.75±0.03 vs 0.78±0.04). The contribution of fat to total EE was higher during PE recovery compared to pre-exercise rest (81.5±4% vs 48±8%) and the interval exercise induced a greater metabolism of fat during PE recovery compared to continuous exercise (53.5 ± 7.2 vs 48.8 ± 6.1 KCal). It is concluded that achieving higher intensities increases the contribution of fat to PE substrate oxidation, which is an important benefit to health and fat mass control control.