Breaking up prolonged sitting with light-intensity walking improves postprandial glycemia, but breaking up sitting with standing does not

Abstract

Objectives: To explore the effects of breaking up prolonged sitting time with standing or light-intensity walking on a range of cardiometabolic risk markers.

Design: A randomised three-period, three-treatment acute crossover trial.

Methods: Ten non-obese adults took part in three trials: (1) uninterrupted sitting; (2) seated with 2-min bouts of standing every 20 min; and (3) seated with 2-min bouts of light-intensity walking every 20 min. Two standardised test drinks (total 80.3 carbohydrate, 50 g fat) were provided after an initial 1-h period of uninterrupted sitting. Plasma glucose and blood pressure were assessed hourly to calculate area under the curve. Total cholesterol, HDL, and triglycerides were assessed at baseline and 5-h. ANOVAs were used to explore between-trial differences.

Results: Glucose area under the curve was lower in the activity-break condition compared to the uninterrupted sitting and standing-break conditions: mean area under the curve 18.5 (95% CI 17, 20), 22.0 (20.5, 23.5), and 22.2 (20.7, 23.7) mmol L/5-h, respectively, p<0.001; no difference between uninterrupted sitting and standing-break conditions (p>0.05). Systolic and diastolic blood pressure area under the curve did not differ significantly between conditions, nor did responses in lipid parameters (p>0.05).

Conclusions: This study suggests that interrupting sitting time with frequent brief bouts of light-intensity activity, but not standing, imparts beneficial postprandial responses that may enhance cardiometabolic health. These findings may have importance in the design of effective interventions to reduce cardiometabolic disease risk.

Keywords: Blood glucose; Exercise; Postprandial period; Sedentary lifestyle.