Twelve weeks of low volume sprint interval training improves cardio-metabolic health outcomes in overweight females

This study compared the effects of 12-week sprint interval training (SIT), high-intensity interval training (HIIT), and moderate-intensity continuous training (MICT) on cardiorespiratory fitness (V.O-2peak), body mass and insulin sensitivity in overweight females. Forty-two overweight women (age 21.21.4years, BMI 26.3 +/- 2.5 kgm(-2)) were randomized to the groups of SIT (80x6-s sprints + 9-s rest), and isoenergetic (300KJ) HIIT (similar to 9x4-min cycling at 90% V.O-2peak+3-min rest) and MICT (cycling at 60% V.O-2peak for similar to 61-min). Training intervention was performed 3 dweek(-1) for 12weeks. After intervention, all three groups induced the same improvement in V.O-2peak (similar to +25%, p <0.001) and a similar reduction in body mass (similar to - 5%, p <0.001). Insulin sensitivity and fasting insulin levels were improved significantly on post-training measures in SIT and HIIT by similar to 26% and similar to 39% (p <0.01), respectively, but remain unchanged in MICT. In contrast, fasting glucose levels were only reduced with MICT (p <0.01). The three training strategies are equally effective in improving V.O-2peak and reducing body mass, however, the SIT is time-efficient. High-intensity training (i.e. SIT and HIIT) seems to be more beneficial than MICT in improving insulin sensitivity.Abbreviations: BMI: body mass index; CVD: cardiovascular disease; HIEG: hyperinsulinaemic euglycaemic glucose; HIIT: high-intensity interval training; HOMA-IR: homeostasis model assessment of insulin resistance; HR: heart rate; MICT: moderate-intensity continuous training; RPE: ratings of perceived exertion; SIT: sprint interval training; T2D: type 2 diabetes; V.O-2peak: peak oxygen consumption