Is Energy Expenditure of Regular Activity Breaks Associated with their Effects on Postprandial Metabolism? Secondary Analysis from the ALPhA and ABPA Studies

Abstract

Background Sedentary behaviour is a well-known risk factor for cardio-metabolic disease. Regularly interrupting prolonged sedentary behaviour with activity breaks has shown to be beneficial for glycaemic control. However, the influence of the energy expended during these activity breaks on metabolic response is relatively unknown. Objective To investigate the potential association between the energy expenditure incurred by regularly interrupting prolonged sitting with short bouts of activity, and postprandial glucose and insulin levels and the triglyceride responses. Design Data was utilised from two separate randomised crossover trials (the ALPhA: Active Living and Physical Activity, and ABPA: Activity Breaks and Physical Activity studies) that investigated the effects of regular activity breaks on postprandial glucose and insulin levels and the triglyceride responses in healthy adult participants, of a normal weight range. Seventy adults participated in 3 single day 9 h interventions in the ALPhA study: 1) prolonged sitting for 9 h, 2) 30 min physical activity and 3) sitting with regular activity breaks (RAB; 1 min and 40 sec of brisk walking) every 30 min. Thirty-six adults completed 4 interventions in the ABPA study: 1) prolonged sitting, 2) sitting and then 30 min activity at the end of day one, and sitting on day two, 3) RAB (2 min of brisk walking) every 30 min, and 4) a combination of physical activity and RAB. Indirect calorimetry was used to estimate energy expenditure. In this secondary analysis, regression modelling was used to determine the association between the energy expended during the regular activity breaks intervention of each study and postprandial glucose, insulin and triglyceride responses. Results Energy expenditure was not found to be associated with postprandial incremental area under the curve (iAUC) for glucose, insulin or triglyceride responses in either study after the adjustment for age, sex, body mass index, carbohydrate content of meal, and baseline fasting values (p>0.05 for all). The relationships between energy expenditure and metabolic response were not substantially different for the regular activity breaks intervention compared to the prolonged sitting. Conclusion While the results of several studies indicate that regular activity breaks reduce postprandial glucose and insulin responses when compared to prolonged sitting, the results of this preliminary investigation indicate that in healthy, normal weight adults, performing moderate intensity regular activity breaks, the energy expenditure related to this activity does not appear to be associated with magnitude of postprandial response.