Short sprints accumulated at school modulate postprandial metabolism in boys

INTRODUCTION: This study examined the efficacy of maximal sprint running accumulated during a typical school day to modulate postprandial metabolism in adolescent boys. METHODS: Nineteen adolescent boys completed three, 2-day experimental conditions; a standard-practice control (CON); accumulated in-school sprint running (ACC); and a single block of afterschool sprint running (BLO). On Day 1, a fasting capillary blood sample was taken at 07:35 in the school. Three subsequent postprandial blood samples were taken at predetermined times after consumption of standardised breakfast and lunch. During ACC, participants accumulated four sets of 10 × 30 m maximal-intensity sprint runs across natural breaks in lessons. During BLO, participants performed the same number of sprints (forty) in a single after-school exercise session. The blood samples from Day 1 were replicated on the day after exercise (Day 2). RESULTS: On Day 1, no significant differences in total area under the plasma triacylglycerol concentration versus time curve (TAUC-TAG) were observed between conditions (P = 0.126). However, TAUC-insulin was lower in ACC compared with BLO (-26%, ES = 0.86, P = 0.001) and CON (-22%, ES = 0.72, P = 0.010). On Day 2, TAUC-TAG was 12% lower after ACC (ES = 0.49; P = 0.002) and 10% lower after BLO (ES = 0.37; P = 0.019) compared with CON. No significant differences were observed between conditions on Day 2 for postprandial insulin or glucose (P ≥ 0.738). CONCLUSION: Four sets of 10 × 30 m sprints, accumulated in four separate bouts (<5 min) during the school day reduced postprandial triacylglycerol and insulin concentrations in adolescent boys and may represent an effective in-school exercise strategy to promote metabolic health.