Six-month physical activity and fitness changes in Project Active, a randomized trial

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Project Active is a randomized clinical trial (N = 235) comparing a lifestyle physical activity program with a structured exercise program in changing physical activity (total energy expenditure [kcal·kg−1·d−1]) and cardiorespiratory fitness (V˙O2peak in mL·kg−1·min−1).


Sedentary but healthy adults (N = 235) aged 35-60 years received 6 months of intensive intervention.


Analysis of covariance (ANCOVA), adjusting for baseline measure, age, gender, body mass index (BMI), cohort, and ethnicity, showed that at 6 months both lifestyle and structured groups significantly increased energy expenditure over baseline (P < 0.001). The mean increases ± SE, 1.53 ± 0.19 kcal·kg−1·d−1 for the lifestyle group and 1.34 ± 0.20 kcal·kg−1 d−1 for the structured group, were not significantly different between groups (P = 0.49). For cardiorespiratory fitness, both groups had significant increases from baseline (P < 0.001). Mean increases ± SE were 1.58 ± 0.33 mL·kg−1·min−1 and 3.64 ± 0.33 mL·kg−1·min−1 for the lifestyle and structured groups, respectively. This was significantly greater in the structured group (P < 0.001). We also studied changes in intensity of physical activity. Both groups significantly increased moderate intensity activity from baseline, but the increase was significantly greater in the lifestyle group than the structured group (P = 0.02). In contrast, the structured group increased its hard activity more than the lifestyle group, but the difference was not significantly different (P = 0.18). Very hard activity significantly increased (P < 0.01) for both groups by 0.25 kcal·kg−1·d−1.


Both intervention approaches are effective for increasing physical activity and fitness over a 6-month period in initially sedentary men and women.

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