Does Energy Expenditure Of Activity Interruptions In Prolonged Sitting Impact On Glycemic Responses?

Abstract

PURPOSE: To explore the impact of energy expenditure (EE) on glycemic responses when prolonged sitting is interrupted by three regular activity bouts. METHODS: Fourteenhealthy, sedentary, inactive adults (8 women; age 23.7±2.9 y; BMI, 22.2±2.4 kg/m2; VO2 max, 38.5±5.2ml·kg-1·min) completed four 26 h interventions in randomized order, including 22.5 h in an EE-testing calorimeter chamber. The four 9 h intervention periods were as follows: uninterrupted sitting (SIT); 30 min sitting/3 min brisk treadmill walk (60% VO2max, WALK3); 45 min sitting/5 min brisk treadmill walk (WALK5); or 60 min sitting/8 min brisk treadmill walk (WALK8). Meals and meal times were standardized across the trials for all participants. After adjustment for age, sex, percent of body fat, relative VO2max, treatment order, and corresponding baseline interstitial glucose concentrations, the relationship between EE and the incremental area under the curve (iAUC) for interstitial glucose was examined during the whole 26 h observation period and each segmentation period (intervention period, evening period, and sleep period). The interstitial glucose was obtained via continuous glucose monitoring. Random effects mixed model analyses were performed and data were represented as unstandardized coefficients with 95% confidence intervals. RESULTS: Model parameter estimates revealed that EE was negatively associated with glucose iAUC during the intervention period (β= -1.87 mmol·h·L-1·MJ-1[-3.68 - -0.05], P=0.04) and positively associated with glucose iAUC during the 2 h post-dinner period immediately following the intervention period (β=0.64 mmol·h·L-1·MJ-1[0.27 - 1.00],P=0.001). There was no significant association between EE and glucose iAUC during the entire 26 h observation or the other segmentation periods. The 2 h post-dinner iAUC was higher in men than in women (mean difference: 0.74 mmol·hL-1[0.16 - 1.33], P=0.01). CONCLUSIONS:Higher EE after the interruption of sitting time was associated with lower interstitial glucose responses during the intervention period in healthy, sedentary adults, but the opposite was true in the 2 h postprandial period immediately following the intervention period.