Effects of interrupting sitting with different activity bouts on postprandial lipemia: A randomized crossover trial

To determine whether interrupting prolonged sitting with three different activity breaks has both acute and chronic effects on postprandial lipid metabolism immediately after the activity-break period and on the following day, this study is a secondary analysis of an experimental research, which included 16 sedentary healthy adults (7 men, 24 ± 3 years, BMI 22.2 ± 2.3 kg/m² ) who completed four 26-h laboratory trials. Participants spent 22.5 hours in a whole room calorimeter for testing energy expenditure (EE), including a 9-h activity-break period: (a) 9-h prolonged sitting (SIT); (b) 3 minutes of brisk walking (60% VO_2max ) in between every 30-min sitting bout (WALK3), (c) 5 minutes every 45-min (WALK5), and (d) 8 minutes every 60-min (WALK8). Total area under the curve (tAUC) and incremental AUC (iAUC) for 2-h postprandial serum triglyceride (TG) levels and non-esterified fatty acid (NEFA) levels were examined immediately after the 9-h trial (post-dinner) and the next morning (post-breakfast). WALK8 reduced the post-breakfast TG tAUC by 11% (P = .041) relative to SIT, and the effect was attenuated after adjustment for EE. The tAUC and iAUC indicated no significant treatment effects on post-dinner TG and NEFA, and post-breakfast NEFA in any of the activity-break trials. EE was positively associated with the post-breakfast NEFA iAUC (unstandardized β = 0.17 µmol/L/MJ [0.05-0.28], P = .006). There was a chronic effect of interrupting sitting with short bouts (8 minutes) of brisk walking every 60 minutes on postprandial lipemia the following morning after intervention, and higher activity bout-induced EE may be more effective in sedentary, healthy adults.