Effects of exercise training amount on physical activity energy expenditure

We examined the effects of three exercise training interventions on total physical activity energy expenditure (PAEE) or nonexercise PAEE in a randomized controlled trial where sedentary, overweight, and obese men and women were assigned to inactive control, low-amount/moderate-intensity, low-amount/vigorous-intensity, or high-amount/vigorous-intensity aerobic exercise.

To measure PAEE, triaxial RT3 accelerometers were worn by subjects for 7 d at the beginning and end of an 8-month exercise intervention. In total, 50 subjects (control, n = 8; two low-amount groups, n = 28; high-amount group, n = 14) had usable PAEE data collected at both time points.

At baseline, subjects had an average age of 53.2 yr, had a body mass index of 29.7 kg x m(-2), and a relative peak VO2 of 28.7 mL x kg(-1) x min(-1). There were no significant differences between groups at baseline. After the intervention, average change in total PAEE was 8.4 +/- 20.9 kJ x h(-1) for controls, 58.6 +/- 20.9 kJ x h(-1) for the two low-amount groups, and 138.1 +/- 33.5 kJ x h(-1) for the high-amount group (means +/- SE). The high-amount group experienced a significantly greater increase in total PAEE compared with the controls (P = 0.02). As expected, total PAEE increased with increasing exercise volume. Average change in nonexercise PAEE was 8.4 +/- 20.9 kJ x h(-1) for control, 25.1 +/- 20.9 kJ x h(-1) for the low-amount groups combined, and 62.8 +/- 29.3 kJ x h(-1) for the high-amount group. There was no statistically significant difference in change of nonexercise PAEE among groups.

We conclude that in middle-aged overweight or obese subjects participating in an extended exercise intervention, total PAEE increased, and there was no compensatory decrease in nonexercise PAEE.