Beneficial postprandial lipaemic effects of interrupting sedentary time with high-intensity physical activity versus a continuous moderate-intensity physical activity bout: A randomised crossover trial

Objectives: To compare the postprandial cardiometabolic response to prolonged sitting, continuous moderate-intensity physical activity (PA) followed by prolonged sitting, and interrupting prolonged sitting with hourly high-intensity PA breaks. Design: Three-condition randomised crossover trial. Methods: Fourteen sedentary and inactive adults aged 29 +/- 9 years took part in three, 8-h conditions: (1) prolonged sitting (SIT), (2) a continuous 30-min moderate-intensity PA bout followed by prolonged sitting (CONT-SIT), and (3) sitting interrupted hourly with 2 min 32 s high-intensity PA bouts (SIT-ACT). The treadmill PA in conditions 2 and 3 were matched for energy expenditure. Two standardised test meals were consumed during each condition. Incremental area under the curve (iAUC) for each 8-h condition was calculated for glucose, insulin, triglyceride, and high-density lipoprotein cholesterol (HDL-C) concentrations. Statistical analyses were completed using linear mixed models. Results: Compared with SIT, SIT-ACT lowered triglyceride iAUC by 2.23 mmol/L.8 h (95% CI -4.33, -0.13) and raised HDL-C iAUC by 0.99 mmol/L.8 h (0.05, 1.93) (all p <= 0.038). There was no significant difference in triglyceride or HDL-C iAUC between CONT-SIT and SIT or SIT-ACT (p >= 0.211). There were no significant differences between conditions for glucose or insulin iAUC (p >= 0.504). Conclusions: This study suggests that interrupting prolonged sitting with hourly high-intensity PA breaks acutely improves postprandial triglyceride and HDL-C concentrations compared with prolonged sitting, whereas a continuous moderate-intensity PA bout does not. (C) 2018 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.