title: Breaking up sedentary time, physical activity and lipoprotein metabolism.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  Eighteen female subjects (25.6years±2.6; 21.5kg/m2±2.0) participated in a balanced crossover experiment with three trials: (1) 30min PA prior to 4h sitting (PRE), (2) 5×6min PA within 4h sitting (BREAK) (3) 4h sitting (CTRL). PA was ergometer cycling at 70%VO2max. Participants consumed one standardized breakfast in each trial.
  
  
  METHODS
  Total cholesterol (tChol), high density lipoprotein (HDL), low density lipoprotein (LDL) and triacylglycerol (TAG) readings were taken in fasted state at the beginning (before), and immediately after each trial. Multiple 2×3-ANOVAs (trial-arm*time) and post hoc t-tests were used.
  
  
  RESULTS
  ANOVAs revealed trial*time-effects for tChol (p=0.043) and HDL (p=0.007) and a tendency for LDL (p=0.078). Before-to-after differences (Δ) of tChol during BREAK-trial (-0.89±5.49mg/dl) significantly differed to Δ during PRE-trial (+3.56±5.32mg/dl) (p=0.005) but not to ΔCTRL (+2.16±8.72). ΔHDL during BREAK-trial (-2.11±3.31mg/dl) significantly differed to ΔPRE (+0.83±4.26mg/dl) (p=0.007) and ΔCTRL (+0.06±4.15mg/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±38.69mg/dl to 94.78±44.86mg/dl) and CTRL (80.94±32.94mg/dl to 97.72±41.19mg/dl) but not in PRE (78.83±33.13mg/dl to 89.06±33.83mg/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.
authors.affiliation: Goethe-University Frankfurt, Department of Sports Medicine, Germany. Electronic address: engeroff@sport.uni-frankfurt.de.
authors.forename: Tobias
authors.initials: T
authors.lastname: Engeroff
authors.affiliation: Goethe-University Frankfurt, Department of Sports Medicine, Germany.
authors.forename: Eszter
authors.initials: E
authors.lastname: Füzéki
authors.affiliation: Goethe-University Frankfurt, Department of Sports Medicine, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Vogt
authors.affiliation: Goethe-University Frankfurt, Department of Sports Medicine, Germany.
authors.forename: Winfried
authors.initials: W
authors.lastname: Banzer
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D015444:Exercise; D005260:Female; D006801:Humans; D050356:Lipid Metabolism; D008074:Lipoproteins / Q000378:metabolism*; D019518:Postprandial Period; D011187:Posture; D057185:Sedentary Behavior; D055815:Young Adult
chemical_list: D008074:Lipoproteins
keywords: Active breaks; Inactivity; Lipid metabolism; Lipoprotein; Sedentary behavior; Sedentary physiology