High-intensity intermittent “5–10–15” running reduces body fat, and increases lean body mass, bone mineral density, and performance in untrained subjects

The present study examined the effect of intense intermittent running with 5 s sprints on body composition, fitness level, and performance in untrained subjects aged 36–53 years. For 7 weeks, the subjects carried out 3 days a week 5–10–15 training consisting of 3–9 blocks of 4 repetitions of 15, 10, and 5 s low-, moderate-, and high-speed running, respectively. Body fat mass was 4.3% lower (P < 0.01), and lean body mass and bone mineral density was 1.1 and 0.9% higher (P < 0.01), respectively, after compared to before the intervention period (INT). The plasma bone turnover markers osteocalcin increased (P < 0.01) by 147%, and procollagen-type I N propeptide and carboxy-terminal collagen crosslinks increased (P < 0.05) by 84 and 76%, respectively. Furthermore, the training improved performance in 1500 m (P < 0.001), 3 km (P < 0.001), Yo–Yo intermittent endurance test (P < 0.01), and incremental treadmill running (P < 0.001) by 8.1, 9.9, 17.2, and 23.9%, respectively. Furthermore, blood lactate after running at 85% of maximal aerobic speed was lower (P < 0.01) after compared to before the INT. Thus, 7 weeks of 5–10–15 training resulted in significant health beneficial changes and better performance in untrained subject.