Objective:To assess the influence of a single bout of exercise on subsequent physical activity and sedentary timeamong overweight boys.Methods:A crossover study on 24 overweight boys (11–13 years old) was conducted with three different exper-imental sessions: control, one bout of moderate exercise, and one bout of vigorous exercise. Physical activity wasmeasured using triaxial accelerometers and time spent in light, moderate, vigorous, and sedentary activities wasassessed during six days of follow-up. Differences in daily percentage of time spent in sedentary, light, moderate,and vigorous activities among experimental sessions were analyzed using linear mixed-effect models.Results:Time spentinsedentary behavior was greater after moderate and vigorous sessions comparedto the con-trol, with statistically significant differences in trajectories between moderate (p = 0.04) and vigorous sessions(p = 0.006) compared to controls. Similarly, the time spent in moderate physical activity was smaller after mod-erate (p = 0.02) and vigorous sessions (p = 0.02) compared to the control. No differences in sedentary (p =0.50) and moderate (p = 0.97) activities were observed between moderate and vigorous sessions. The percent-age of time spent in vigorous physical activity showed a greater reduction in vigorous condition compared tomoderate and control (pb0.01) conditions, while time spent in light physical activities was not different be-tween sessions.Conclusions:Our results indicate a compensatory effect after a single bout of exercise due to decreases in moder-ate and vigorous physical activity and increases in sedentary time during the following six days.2020-08-05