Examining the moderating effect of depressive symptoms on the relation between exercise and self-efficacy during the initiation of regular exercise

Objective: People with depressive symptoms report lower levels of exercise self-efficacy and are more likely to discontinue regular exercise than others, but it is unclear how depressive symptoms affect the relation between exercise and self-efficacy. We sought to clarify whether depressive symptoms moderate the relations between exercise and same-day self-efficacy, and between self-efficacy and next-day exercise. Methods: Participants (n = 116) were physically inactive adults (35% reported clinically significant depressive symptoms) who initiated regular exercise and completed daily assessments for 4 weeks. Mixed linear models were used to test whether (a) self-efficacy differed on days when exercise did and did not occur, (b) self-efficacy predicted next-day exercise, and (c) these relations were moderated by depressive symptoms. Results: First, self-efficacy was lower on days when no exercise occurred, but this difference was larger for people with high depressive symptoms (p < .001). They had lower self-efficacy than people with low depressive symptoms on days when no exercise occurred (p < .03), but self-efficacy did not differ on days when exercise occurred (p < .34). Second, self-efficacy predicted greater odds of next-day exercise, OR = 1.12, 95% [1.04, 1.21], but depressive symptoms did not moderate this relation, OR = 1.00, 95% CI [.99, 1.01]. Conclusions: During exercise initiation, daily self-efficacy is more strongly related to exercise occurrence for people with high depressive symptoms than those with low depressive symptoms, but self-efficacy predicts next-day exercise regardless of depressive symptoms. The findings specify how depressive symptoms affect the relations between exercise and self-efficacy and underscore the importance of targeting self-efficacy in exercise interventions, particularly among people with depressive symptoms.