Timing of Exercise Among Young Adults Previously Enrolled in a Randomized Controlled Weight Management Trial: An Observational Study

Abstract

This study examined self-reported exercise time of day and psychosocial/behavioral correlates in a cohort of young adults previously enrolled in a randomized controlled weight management trial. An online survey was distributed to participants of the trial 2 years after conclusion. Questions assessed physical activity (PA), PA self-efficacy, sleep parameters, and BMI. One item assessed exercise timing: “During the last 7 days, I tended to exercise in the…” Response options included: Early morning (04:00-08:59 am), Mid-morning (09:00-11:59 am), Afternoon (12:00-04:59 pm), Evening (05:00 pm-3:59 am), varied times, or no exercise. Differences in baseline or follow-up characteristics were examined across exercise time using Fisher’s Exact and Kruskal–Wallis tests. Of 107 participants contacted, 38 responded, and 31 provided eligible responses. Evening exercise was most frequently reported (N = 11), followed by varied times (N = 10), early morning (N = 4), mid-morning (N = 4), and afternoon (N = 2). PA self-efficacy was highest in evening exercisers (16.1 ± 2.6) compared with those exercising at other times ( P = .015). Moderate-to-vigorous PA was also highest in evening exercisers (265.0 ± 123.1 min/week) compared with those exercising at other times ( P = .035). Pending evidence from larger observational studies, evening may be a relatively popular time to exercise among young adults, and may be associated with greater PA self-efficacy and weekly PA.