Breaking up sedentary time, physical activity and lipoprotein metabolism

Objectives: Some authors report delayed responses of lipid metabolism after prolonged and interrupted sitting. To date no experimental studies have shown acute physical activity (PA) related changes of lipoprotein metabolism during sedentary behavior (SB). The purpose of this study was to examine immediate effects of a single PA-bout vs. regular PA-breaks on lipoprotein metabolism during postprandial SB. Design: Eighteen female subjects (25.6years +/- 2.6; 21.5 kg/m2 +/- 2.0) participated in a balanced crossover experiment with three trials: (1) 30 min PA prior to 4 h sitting (PRE), (2) 5 x 6 min PA within 4 h sitting (BREAK) (3) 4h sitting (CTRL). PA was ergometer cycling at 70%VO(2)max. Participants consumed one standardized breakfast in each trial. Methods: Total cholesterol (tChol), high density lipoprotein (HDL), low density lipoprotein (LDL) and triacyiglycerol (TAG) readings were taken in fasted state at the beginning (before), and immediately after each trial. Multiple 2 x 3-ANOVA5 (trial-arm*time) and post hoc t-tests were used. Results: ANOVA5 revealed triartime-effects for tChol (p = 0.043) and HDL (p = 0.007) and a tendency for LDL (p = 0.078). Before-to-after differences (Delta) of tChol during BREAK-trial (-0.89 +/- 5.49 mg/dI) significantly differed to Delta during PRE-trial (+3.56 +/- 5.32 mg/dl) (p = 0.005) but not to Delta CTRL (+2.16 +/- 8.72). Delta HDL during BREAK-trial (-2.11 +/- 3.31 mg/dl) significantly differed to Delta PRE (+0.83 +/- 4.26 mg/dl) (p = 0.007) and Delta CTRL (+0.06 +/- 4.15 mg/dl) (p = 0.028). Analysis of TAG revealed a time effect (p = 0.007) and significant differences between TAG before and after trial within BREAK (79.22 +/- 38.69 mg/di to 94.78 +/- 44.86 mg/di) and CTRL (80.94 +/- 32.94 mg/dl to 97.72 +/- 41.19 mg/dl) but not in PRE (78.83 +/- 33.13 mg/dl to 89.06 +/- 33.83 mg/dl). Conclusions: Breaking sedentary behavior with vigorous intensity PA seem to decelerate, postprandial lipoprotein metabolism during sitting. In contrast, prior PA, might be a stimulus for lipid metabolization. (C) 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.