Adherence and attrition with intermittent and continuous exercise in overweight women

Few people are active to the levels recommended by Healthy People 2010. Intermittent exercise has been promoted as an exercise prescription which may enable more people to meet recommended guidelines. However, few data are available on intermittent exercise over the long-term. The purpose of the current study was to compare the effects of long-term (72 weeks) continuous (CON) and intermittent (INT) exercise on attrition and adherence in previously sedentary, moderately obese females. Participants were randomized to continuous walking at 60 to 75% of maximum aerobic capacity, 3 days per week, 30 minutes per session, or intermittent exercise for two 15-minute sessions, 5 days per week. Adherence was calculated as the number of sessions completed compared to the number of sessions prescribed. At 12-week intervals, attrition was calculated as the number of participants in the study compared to the total number of participants originally enrolled. For the participants who completed the study, body weight decreased for CON from 80.17 +/- 5.75 kg at baseline to 79.70 +/- 5.40 at 16 months (p < 0.05). For INT, body weight did not change from baseline (85.85 +/- 13.13 kg) to 16 months (85.05 +/- 12.90 kg). By design, INT walked significantly (p < 0.05) further (819 +/- 128 km) compared to CON (527 +/- 46 km). Attrition was 58% for both groups baseline to 72 weeks. However, attrition was greater for CON (38 %) compared to INT (16%) in the first 24 weeks. Adherence was excellent for both groups (> 83%) throughout the study. These results suggest that intermittent and continuous exercise both have considerable attrition rates within 72 weeks of exercise initiation; however, the pattern of attrition differs considerably. That is, it appears that intermittent exercise may reduce attrition in the first 24 weeks of an exercise program; however, attrition does not appear to be different than continuous exercise at 72 weeks.