Background: Sedentary behaviour is a risk factor for cardiovascular disease and adverse cardiometabolic responses. Taking regular breaks from sedentary time lowers post-prandial glycaemia; however, little is known about its effect on appetite. An understanding of this relationship may provide further information about how sedentary behaviour is related to health and disease outcomes over time.
Objective: To determine if appetite in response to a test breakfast differs when taking regular activity breaks compared to prolonged sitting.
Design: Data for this study were collected from a randomised, cross-over, laboratory-based intervention trial. Thirty-six healthy, typically sedentary adults (mean age 25 y (SD 3.9), BMI 23.9 kg/m2 (SD 3.9)) completed four two-day interventions (6.5 h on Day 1, 5 h on Day 2), each separated with ~5 days washout: (1) Uninterrupted sitting on both days (SED); (2) sitting interrupted with 2-minute walks (regular activity breaks) every thirty minutes (RAB); (3) sitting combined with a 30 minute walk at the end of Day 1 but only uninterrupted sitting on Day 2 (SED+PA); and (4) regular activity breaks (on both days) combined with a 30 minute walk at the end of Day 1 (RAB+PA). For the first meal of Day 1, participants consumed a carbohydrate-based breakfast, and for the first meal of Day 2 a high-fat breakfast. During each two-day intervention, participants completed a five-question, visual analogue scale appetite and satiety questionnaire every sixty minutes. The mean of these five responses was then used as a single appetite score that measured overall hunger at each time point postprandially for ~3 h on Days 1 and 2. Area under the curve (AUC) for overall hunger was then calculated for this time period on Day 1 and Day 2 separately. Linear mixed models were used to compare appetite response (by AUC) between interventions and between days.
The timing of the physical activity (Day 1 of interventions SED+PA and RAB+PA) meant that it was unlikely for it to affect appetite on the next morning (Day 2). Therefore, the mean of the data from SED and SED+PA interventions is described as SED, and the mean of the data from RAB and RAB+PA interventions is described as RAB. This allowed comparisons between the regular activity breaks and sedentary behaviour interventions.
Outcomes: There was no significant difference in appetite AUC between the RAB and the SED interventions (Day 1: standardised effect 0.08; 95%CI -0.27, 0.11; p=0.394. Day 2: standardised effect 0.05, 95%CI -0.13, 0.23; p=0.588). When adjusted for intervention, Day 2 appetite AUC was 0.2 SD higher than Day 1 (95%CI 0.04, 0.33; p=0.011), showing an increased appetite response (higher hunger levels) to the high-fat croissant breakfast.
Conclusion: Interrupting prolonged sitting with regular activity breaks does not appear to increase appetite. Therefore, longer-term investigation into the effects of regular activity breaks on energy balance may be warranted.
