EFFECT OF EXERCISE DURATION AND INTENSITY OF FITNESS, WEIGHT LOSS, AND BODY COMPOSITION IN OVERWEIGHT ADULTS

Abstract

Exercise is a significant behavioral factor for enhancing weight loss, however the optimal duration and intensity of exercise remains questionable. This study examined different doses of exercise on changes in fitness, weight loss, and body composition in overweight adults. Ninety-seven of 99 sedentary women (BMI = 32.9 ± 4.0 kg/m2, age = 37.6 ± 5.2 years) completed the initial 24 weeks of a 2-year behavioral weight loss program. The dietary intervention included strategies to reduce calorie intake and fat intake. Exercise was prescribed for 5 days/week. Subjects were randomly assigned to exercise for either 1000 (MD) or 2000 (HD) kcal/wk at either a moderate (MI) or vigorous (VI) exercise intensity. Thus, subjects were assigned to one of four exercise groups: MD/MI, MD/VI, HD/MI, HD/VI. Mean exercise duration was 171, 167, 191, and 195 min/wk in MD/MI, MD/VI, HD/MI, and HD/VI, respectively. Ratings of perceived exertion were MD/MI = 11.9, MD/VI = 13.5, HD/MI = 11.9, and HD/VI = 12.8 (p ≤ 0.05), with exercise heart rate (bpm) being MD/MI = 115, MD/VI = 138, HD/MI = 118, and HD/VI = 140 (p ≤ 0.05). Fitness increased significantly in all groups (MD/MI = 10%, MD/VI = 10%, HD/MI = 15%, HD/VI = 21%), with HD/MI and HD/VI increasing greater than MD/MI and MD/VI (p ≤ 0.05). Weight loss did not differ between groups (MD/MI = 7.5kg, MD/VI = 7.7kg, HD/MI = 8.5kg, HD/VI = 9.3kg), and percent body fat showed a similar decrease. Thus, a greater volume of exercise may result in greater increases in fitness in overweight adults. However, greater volumes of exercise may not result in greater reductions in weight within a 24-week behavioral program. Subjects are being followed to assess the impact across a 2-year period. Supported by the National Institutes of Health (HL64991)