Effects of thirty and sixty minutes of moderate-intensity aerobic exercise on postprandial lipemia and inflammation in overweight men: a randomized cross-over study

Abstract

Background: The transient rise in blood lipids following a high-fat meal (HFM), known as postprandial lipemia, is linked to systemic inflammation and cardiovascular disease, but can be blunted by exercise. However, minimal research has investigated the effects of realistic exercise bouts on postprandial lipemia and inflammation in at-risk individuals. The purpose of this study was to assess the effects of moderate-intensity aerobic exercise lasting 30 or 60 min performed the evening before a HFM, on postprandial lipemia and inflammation in overweight, insufficiently active men.

Methods: In this randomized-crossover study, twelve participants remained sedentary (CON), or performed a brisk walk on a treadmill at 60 % VO2peak for either 30 min (EX-30) or 60 min (EX-60), after which they consumed a small snack (270 kcal) to partially replace exercise energy expenditure. Following a 12-h overnight fast, participants consumed a standard HFM (1 g fat/kg; 1 g CHO/kg; 1117.8 ± 117.0 kcal). Blood draws were performed at baseline (pre-HFM) and 1, 2, 4, 6, and 8 h post-HFM to assess glucose, insulin, lipids, and systemic inflammation.

Results: There were no significant differences (p > 0.05) in fasting triglycerides between EX-60 (118.7 ± 68.3 mg/dL), CON (134.8 ± 66.2 mg/dL) or EX-30 (135.5 ± 85.4 mg/dL). There were no differences in peak, time-to-peak, total or incremental area-under-the-curve between trials for triglyceride response (p > 0.05). There was no significant main effect of time (p > 0.05) in IL-1ra, IL-4, IL-5, IL-6, IL-10 or TNF-α from baseline to 8 h post-HFM in any trial.

Conclusions: In summary, we found that in overweight, insufficiently active men, neither 30 nor 60 min of moderate-intensity exercise performed 12 h prior to a HFM attenuated postprandial lipemia or inflammation, which could potentially be explained by the partial caloric replacement of exercise energy expenditure.

Keywords: Cytokines; High fat meal; Triglycerides.

Fig. 1

Schematic of study protocol. Participants either exercised (EX-30, EX-60) or remained sedentary (CON) the evening before (~12 h) the meal tolerance test. Resting metabolic rate (RMR) and respiratory exchange ratio (RER) were assessed for 30 min upon arrival at the laboratory the next morning, and again between hours 7 and 8 post-high fat meal (HFM). Blood draws (black arrows) were performed at baseline and 1, 2, 4, 6, and 8 h after the HFM. The HFM was consumed immediate after the baseline blood draw. RMR, resting metabolic rate; RER, respiratory exchange ratio; HFM, high-fat meal

Fig. 2

Hourly metabolic responses to the high-fat meal. These figures display the hourly triglyceride (top panel), glucose (middle panel), and insulin (bottom panel) responses to a high-fat meal in the CON, EX-30, and EX-60 trials. Blood draws were performed at baseline (time 0) and serially 1, 2, 4, 6, and 8 h after the high fat meal. Data are presented as Mean ± SE. In two-way repeated measures ANOVA, there were no significant trial effects for triglycerides, glucose, or insulin (p > 0.05), although there were some between-trial differences with regard to triglycerides at certain time points. * CON significantly different than EX-60. ^# EX-30 significantly different than EX-60

Fig. 3

Hourly inflammatory responses to the high-fat meal. These figures display the hourly interleukin (IL)-4 (top panel), IL-6 (middle panel), and IL-10 (bottom panel) responses to a high-fat meal in the CON, EX-30, and EX-60 trials. IL-4, IL-6, and IL-10 are commonly assessed cytokines in previous studies. Blood draws were performed at baseline (time 0) and serially 1, 2, 4, 6, and 8 h after the high fat meal. Error bars reflect standard error (SE). There were no significant trial effects for any cytokines (p > 0.05), nor were there trial differences at any time points. IL, interleukin