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


Medicine & Science in Sports & Exercise: July 1998 - Volume 30 - Issue 7 - p 1076-1083

Six-month physical activity and fitness changes in Project Active, a randomized trial. Med. Sci. Sports Exerc., Vol. 30, No. 7, pp. 1076-1083, 1998.

Purpose: 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).

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

Results: 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.

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

Cooper Institute for Aerobics Research, Dallas, TX 75230; Vanderbilt University Medical Center, Nashville, TN 37232; The Miriam Hospital and Brown University School of Medicine, Providence, RI 02906; and Baylor College of Medicine, Baylor Sports Medicine Institute, Houston, TX 77030

Submitted for publication July 1997.

Accepted for publication January 1998.

The authors gratefully acknowledge the efforts of the participants, interns, staff, and the Project Officer of Project Active. Staff includes Carolyn Barlow, Laura Becker, Ruth Ann Carpenter, Jo Coetzee, M.D., Sheila Darroch, Larry Gibbons, M.D., Keller Greenfield, M.D., Alan Levitt, Melba Morrow, Stephanie Parker, Nancy Pierce, Patrick Quinn, Ray Thompson, and Jody Wilkinson, M.D. The Project Officer was Elaine Stone. Funding for this study was from National Institutes of Health Grants HL 48597, K07CA01757, and R29CA59660 and by donations of exercise equipment from Nordic Track, Stairmaster, Cybex, PreCor, and the Yamax Corporation.

Address for correspondence: Andrea L. Dunn, Cooper Institute for Aerobics Research, 12330 Preston Road, Dallas, TX 75230. e-mail:

© Williams & Wilkins 1998. All Rights Reserved.