Acute High-Intensity Interval Running Reduces Postprandial Lipemia in Boys

Introduction: Acute moderate-intensity exercise reduces postprandial lipemia in boys. However, the effect of high-intensity exercise has not been investigated. This study examined the effect of low-volume, high-intensity interval running (HIIR) on postprandial plasma triacylglycerol (TAG) concentrations. Methods: Fifteen healthy, active boys (means +/- SD; age = 11.8 +/- 0.4 yr, body mass = 42.8 +/- 8.0 kg, peak oxygen uptake [VO2] = 55 +/- 6 mL.kg(-1).min(-1)) completed two 2-d trials in a counterbalanced, crossover design separated by 14 d. On day 1, participants rested (CON) or completed 10 x 1 min running intervals at 100% maximal aerobic speed, determined from an incremental peak VO2 test, with 1 min recovery between intervals (HIIR). On day 2, capillary blood samples were taken in the fasted state and at predetermined intervals throughout the 6.5-h postprandial period while participants rested. A standardized breakfast was consumed at 0800 h, immediately after the fasting sample, and a standardized lunch meal was consumed at 1200 h. Results: Differences in fasting plasma TAG concentration were small to moderate (95% confidence interval [CI] = -0.11 to 0.01, effect size [ES] = 0.40). Postprandial TAG concentration was lower during HIIR compared with CON (95% CI = -0.19 to -0.02, ES = 0.58). The total area under the TAG concentration versus time curve was lower after HIIR compared with CON (5.2 +/- 1.1 vs 5.8 +/- 1.5 mmol.L-1 6.5 h; 95% CI = -1.18 to -0.12, ES = 0.50). Conclusion: This is the first study to show that low-volume HIIR attenuates postprandial TAG concentration in healthy, active 11- to 12-yr-old boys.