Who Exercises and When? The Effects of Intra- and Inter-Individual Variation on the Likelihood and Duration of Exercise By

The current study examined the ability of interand intra-individual characteristics to predict the likelihood and duration of exercise as well as mood. One hundred forty-nine undergraduates (mean age = 19.11; 53% women; 79.19% White) participated in a six-day study. Online surveys measured participants’ self-reported exercise duration, emotion-regulation ability, hostility, depressive symptoms, sleep quality, anger, and mood. Higher depressive symptoms predicted higher odds of exercise. Higher hostility predicted lower odds of exercise but, on days when participants did exercise, higher duration of exercise. Higher anger predicted lower odds of exercise. Better sleep quality predicted higher positive and lower negative mood but only for older participants. Higher depressive symptoms predicted higher negative and lower positive mood. Results suggest an indirect relationship between hostility and heart disease may exist, via the relationship of hostility to exercise. Further research should investigate causality and the effectiveness of exercise interventions that foster exercise-conducive environments.