Exercise Adherence, Cardiopulmonary Fitness, and Anthropometric Changes Improve Exercise Self-Efficacy and Health-Related Quality of Life

Background: Regular exercise increases exercise self-efficacy and health-related quality of life (HRQOL); however, the mechanisms are unknown. We examined the associations of exercise adherence and physiological improvements with changes in exercise self-efficacy and HRQOL. Methods: Middle-aged adults (N = 202) were randomized to 12 months aerobic exercise (360 minutes/week) or control. Weight, waist circumference, percent body fat, cardiopulmonary fitness, HRQOL (SF-36), and exercise self-efficacy were assessed at baseline and 12 months. Adherence was measured in minutes/day from activity logs. Results: Exercise adherence was associated with reduced bodily pain, improved general health and vitality, and reduced role-emotional scores (P-trend <= 0.05). Increased fitness was associated with improved physical functioning, bodily pain and general health scores (P-trend <= 0.04). Reduced weight and percent body fat were associated with improved physical functioning, general health, and bodily pain scores (P-trend < 0.05). Decreased waist circumference was associated with improved bodily pain and general health but with reduced role-emotional scores (P-trend <= 0.05). High exercise adherence, increased cardiopulmonary fitness and reduced weight, waist circumference and percent body fat were associated with increased exercise self-efficacy (P-trend < 0.02). Conclusions: Monitoring adherence and tailoring exercise programs to induce changes in cardiopulmonary fitness and body composition may lead to greater improvements in HRQOL and self-efficacy that could promote exercise maintenance.