Expectancy-value constructs and expectancy violation as predictors of exercise adherence in previously sedentary women.

This prospective study examined effects of expectancy of exercise benefits, value of benefits, expectancy violation, and self-efficacy (SE) on exercise behavior and study dropout in sedentary women (n=86). SE predicted exercise for study completers but did not predict study dropout. After 6 and 12 weeks, participants evidenced expectancy violations, particularly for fitness and weight. Initial value, expectancy, and Expectancy X Value did not predict exercise for study completers, but dropouts had higher initial positive expectancies than did completers. Expectancy violations produced in Weeks 1-6 did not predict exercise in Weeks 7-12 in study completers, but dropouts in Weeks 7-12 had higher expectancy violations for weight in Weeks 1-6 than did completers. Follow-up revealed that study dropouts stopped exercising. Identifying individuals with high initial expectancies and expectancy violations may improve health behavior intervention and research.