Sprint Interval Training (SIT) and the school curriculum: benefits upon the cardiorespiratory fitness, physical activity profiles and cardiometabolic risk profiles of healthy adolescents

Background: This study examined the impact of 4-weeks of a school-based sprint interval training (SIT) programme on cardiorespiratory fitness (CRF), daily physical activity (PA) behaviour and cardiometabolic risk (CMR) outcomes in adolescents. Methods: Fifty-six adolescents (22 females) were allocated to either an intervention (INT) (n = 22, 17.0 (0.3) years) or control group (CON) (n = 30, 16.8 (0.5) years). INT performed 5-6, 30 s “all out” running sprints, interspersed with 30s rest intervals, 3 times per week, for 4 consecutive weeks while CON performed their normal physical education lessons. CRF was estimated from the 20m Multi Stage Fitness Test and PA behaviour was determined by accelerometery. Fasted blood samples were obtained to measure biochemical markers of CMR. Results: Significant group x time interactions were observed for CRF (5.03 (1.66 - 8.40); p <0.001; d = 0.95), sedentary time (136.15 (91.91 - 180.39); p = 0.004; d = 1.8), Moderate PA (57.20 (32.17 - 82.23); p <0.001; d = 1.5), vigorous PA (5.40 (4.22 - 6.57); p < 0.001; d = 1.2), fasting insulin (0.37 (-0.48 - 1.21); p = 0.005; d = 1.0), HOMA-IR (0.26 (0.15 - 0.42); p < 0.001; d = 0.9) and clustered CMR score (0.22 (-0.05 -0.68; p < 0.001; d = 10.63). Conclusion: Findings of this study indicate that 4 weeks of school-based SIT improves CRF, improves PA profiles and maintains CMR in adolescents during the school term.