High-intensity running and energy restriction reduces postprandial lipemia in girls

PURPOSE: This study examined the potency of combining acute high-intensity exercise and energy-intake restriction on postprandial triacylglycerol concentrations ([TAG]) in healthy girls. METHODS: Sixteen 11- to 13-year-old girls (mean(SD): body mass 45.1(7.6) kg; peak oxygen uptake (V˙O2) 43(6) mL·kg·min) completed three, 2-day conditions in a counterbalanced, crossover design separated by 14 days. On day 1, participants completed 10×1 min interval runs (HIIR), 5×1 min interval runs combined with 0.82(0.19) MJ energy-intake restriction (HIIR-ER) or rested (CON). Exercise was completed at 100% maximal aerobic speed, determined from an incremental peak V˙O2 test, with 1 min recovery between intervals. On day 2, capillary blood samples were taken in the fasted state and at pre-determined intervals throughout the 6.5 h postprandial period. A standardised breakfast and lunch were consumed immediately and 4 h, respectively, after the fasting sample. RESULTS: Based on ratios of the geometric means (95% confidence intervals (CI) for ratios), fasting [TAG] was 16% and 8% lower than CON in HIIR (-24 to -7%, effect size (ES) = 0.49, P = 0.002) and HIIR-ER (-17 to 1%, ES = 0.24, P = 0.09) respectively; HIIR was 8% lower than HIIR-ER (-17 to 1%, ES = 0.25, P = 0.08). The total area under the [TAG] versus time curve was 10% and 9% lower than CON in HIIR (-16 to -3%, ES = 0.30, P = 0.01) and HIIR-ER (-15 to -2%, ES = 0.28, P = 0.01) respectively; HIIR-ER and HIIR were similar (-1%; -8 to 6%, P = 0.80). CONCLUSION: Manipulations of HIIR and ER reduce postprandial [TAG] in girls. The magnitude of effect was marginally, though not meaningfully, greater following HIIR than HIIR-ER.