A randomized trial of physical activity interventions: design and baseline data from Project Active

KOHL, HAROLD W. III; DUNN, ANDREA L.; MARCUS, BESS H.; BLAIR, STEVEN N.

Medicine & Science in Sports & Exercise: February 1998 - Volume 30 - Issue 2 - pp 275-283
Basic Sciences: Epidemiology

We report here the design and baseline data from Project Active, a 2-yr randomized trial designed to compare the effectiveness of a Lifestyle physical activity intervention with the traditional Structured exercise prescription approach. Primary outcome measures are energy expenditure in physical activity(estimated by kcal per kilogram of body weight of energy expenditure) and cardiorespiratory fitness (measured by maximal oxygen uptake). The participants, 235 initially sedentary and apparently healthy adults, were randomized into either the Lifestyle or Structured intervention groups. The Lifestyle treatment consists of a personalized approach that accounts for an individual's motivational readiness and preferences for integrating physical activity into daily routines. The Structured approach is the familiar exercise prescription that is based on a frequency, intensity, and duration formula. The primary hypothesis to be tested is that there will be a difference in physical activity and cardiorespiratory fitness measures between the two conditions at the end of 24 months. The secondary hypothesis is that both groups will make significant improvements from baseline in physical activity and cardiorespiratory fitness at the end of 6 months. Six months of active intervention are followed by 18 months of a tapered follow-up maintenance intervention in both groups. Primary outcome measures are measured after 6 and 24 months.

Cooper Institute for Aerobics Research, Division of Epidemiology and Clinical Applications, Dallas, TX; The Miriam Hospital/Brown University, School of Medicine, Providence, RI; and Baylor College of Medicine, Baylor Sports Medicine Institute, Houston, TX

Submitted for publication November 1996.

Accepted for publication June 1997.

We gratefully acknowledge the input of Ralph F. Frankowski, Ph.D., R. Sue McPherson, Ph.D., Milton Z. Nichaman, M.D., Sc.D., Abby C. King, Ph.D., and Guy S. Parcel, Ph.D., and Neil F. Gordon, M.D., Ph.D. to the design of Project Active. We gratefully acknowledge the efforts of the participants and staff of Project Active: Carolyn E. Barlow, Laura E. Becker, Ruth Ann Carpenter, Jo Coetzee, M.D., Sheila Darroch, Melissa Garcia, Keller S. Greenfield, M.D., James Kampert, Ph.D., Alan Levitt, Melba S. Morrow, Stephanie Parker, Nancy Pierce, Patrick Quinn, Ray Thompson, Jody Wilkinson, M.D., and numerous student interns. Funding for this study is from the National Institutes of Health (1R018HL 4859701, K07C A01757, and R29CA 59660) and by donations of exercise equipment from Nordic Track, Stairmaster, Cybex, and PreCor.

Current address for Drs. Dunn and Blair: Cooper Institute for Aerobics Research, Division of Epidemiology and Clinical Applications, 12330 Preston Rd., Dallas, TX 75230.

Current address for Dr. Marcus: Division of Behavioral and Preventive Medicine, The Miriam Hospital/Brown University, School of Medicine, 164 Summit Ave., Providence, RI 02906.

Address for correspondence: Harold W. Kohl, III, Ph.D., Baylor Sports Medicine Institute, Baylor College of Medicine, 6560 Fannin, Suite 400, Houston, TX 77030. E-mail: hkohl@bcm.tmc.edu.

©1998The American College of Sports Medicine