Plain language summary
The number of hours in a day is fixed and finite, distributed between obligatory time (such as time spent working, sleeping, domestic activities, commuting or eating) and discretionary time (the remaining ‘free’ time). The way individuals restructure the timing of their behaviours can influence the effectiveness of exercise, and have important health consequences, depending on what activities are displaced. The aim of this study was to investigate how previously inactive adults restructure their time when they undertake morning or evening exercise. This study was conducted within a larger randomised controlled trial which used a three-armed, randomised controlled trial design, with a 12-week lifestyle intervention. Participants (n = 100) were randomized into one of two intervention groups, or a waitlist control group at a 2:2:1 ratio. Results showed that time spent engaging in physical activity was significantly increased from baseline at both mid- and post-intervention for both intervention groups. Furthermore, participants in both intervention groups reported more time spent sleeping, and less time watching television/playing videogames. Authors conclude that the time for exercise was largely drawn from a discretionary time (watching TV), and the patterns of change in time use was similar when exercise was performed in the morning compared with the evening.
Abstract
The objective of this study was to investigate changes in sedentary and active behaviors when previously inactive adults start exercising in the morning or evening. One-hundred adults with overweight or obesity (BMI ≥ 25 kg/m2) were recruited for a 12-week intervention and randomized to one of three groups: (i) morning exercise (AMEx; 0600-0900); (ii) evening exercise (PMEx; 1600-1900); or (iii) waitlist control. AMEx and PMEx were prescribed self-paced aerobic exercise to achieve a weekly total of 250 min via a combination of supervised and unsupervised training. Sedentary and active behavior times were measured at baseline, mid- and post-intervention using the multimedia activity recall for children and adults. Time spent engaging in physical activity was significantly increased from baseline at both mid- (+ 14-22 min·day-1) and post-intervention (+ 12-19 min·day-1), for AMEx and PMEx. At 12-weeks, participants in both morning and evening exercise groups reported increased time spent Sleeping (+ 36 and + 20 min·day-1, respecitively), and reduced time spent watching TV/playing videogames (- 32 and - 25 min·day-1, respectively). In response to an exercise stimulus, previously inactive adults make encouraging modifications in how they use their time, and the patterns of change are similar with morning and evening exercise.
Methodological quality
Jadad score
:
3
Allocation concealment
:
Yes
