Comparison of Lifestyle and Structured Interventions to Increase Physical Activity and Cardiorespiratory Fitness: A Randomized Trial.

Dunn AL, Marcus BH, Kampert JB, et al (The Cooper Institute for Aerobics Research, Dallas, Texas; Miriam Hospital and Brown University School of Medicine, Providence, RI; Baylor College of Medicine, Houston, Tex; Vanderbilt University Medical Center, Nashville, Tenn), JAMA. 1999;281:327-334.

The purpose of this study was to compare the effects of a lifestyle physical activity program and a traditional structured exercise program on improving physical activity, cardiorespiratory fitness, and cardiovascular disease risk factors over a 24-month intervention. The study subjects were men (n = 116) and women (n = 119) who were sedentary with a self-reported physical activity level of less than 36 and 34 kcal/kg per day, respectively. The subjects were randomly assigned to either a lifestyle physical activity program or a structured exercise program. The authors defined a lifestyle physical activity program as a behaviorally based program "in which individuals increase moderate-intensity physical activity as part of their daily routines." The study did not include a control group because physical inactivity is known to increase the risk for several chronic diseases and to decrease longevity.

Participants in both groups received 6 months of intensive intervention and 18 months of maintenance intervention. Subjects in the structured exercise group received a traditional exercise prescription (exercise intensity of 50%-85% of maximal aerobic power for 20-60 minutes). Participants in the lifestyle activity group were advised to perform at least 30 minutes of moderate-intensity physical activity on most, and preferably all, days of the week, in a way uniquely adapted to each person's lifestyle. The subjects met with "group facilitators" who provided them with cognitive and behavioral strategies that were related to physical activity behavior.

Both the lifestyle and the structured interventions produced significant and comparable beneficial changes in physical activity, cardiorespiratory fitness, blood pressure, and percentage of body fat at 24 months. According to the authors, the data supported their hypothesis that a behaviorally based lifestyle physical activity intervention can significantly increase physical activity and fitness at 24 months. The fact that the behaviorally based lifestyle intervention produced benefits comparable to a traditional structured approach was an unanticipated finding. The researchers stated that the results show that individuals who were previously sedentary, but otherwise healthy, can make significant improvements in physical activity, cardiorespiratory fitness, and the risk factors for cardiovascular disease without performing high-intensity exercise.

Brad Stockert, PhD, PT
University of the Pacific
Stockton, Calif