Matsuo T, Ohkawara K, Seino S, Shimojo N, Yamada S, Ohshima H, Tanaka K, Mukai C. An exercise protocol designed to control energy expenditure for long-term space missions. Aviat Space Environ Med 2012; 83:783–9.Introduction: Astronauts experience weight loss during spaceflight. Future space missions require a more efficient exercise program not only to maintain work efficiency, but also to control increased energy expenditure (EE). When discussing issues concerning EE incurred through exercise, excess post-exercise energy expenditure (EPEE) must also be considered. The aim of this study was to compare the total EE, including EPEE, induced by two types of interval cycling protocols with the total EE of a traditional, continuous cycling protocol. Methods: There were 10 healthy men, ages 20 to 31 yr, who completed 3 exercise sessions: sprint interval training (SIT) consisting of 7 sets of 30-s cycling at 120% Vo_2max with a 15-s rest between each bout; high-intensity interval aerobic training (HIAT) consisting of 3 sets of 3-min cycling at 80-90% Vo_2max with a 2-min active rest at 50% Vo_2max; and continuous aerobic training (CAT) consisting of 40 min of cycling at 60-65% Vo_2max. During each session, resting metabolic rate, exercise EE, and a 180-min post-exercise EE were measured. Results: The EPEEs during the SIT, HIAT, and CAT averaged 32 ± 19, 21 ± 16, and 13 ± 13 kcal, and the total EE for an entire exercise/rest session averaged 109 ± 20, 182 ± 17, and 363 ± 45 kcal, respectively. While the EPEE after the CAT was significantly less than after the SIT, the total EE with the CAT was the greatest of the three. Discussion: The SIT and HIAT would be potential protocols to control energy expenditure for long space missions.