HIIT produces increases in muscle power and free testosterone in male masters athletes

High intensity interval training (HIIT) improves peak power output (PPO) in sedentary aging men but has not been examined in masters endurance athletes. Therefore, we investigated whether a 6-week programme of low volume HIIT would (i) improve PPO in masters athletes and (ii) whether any change in PPO would be associated with steroid hormone perturbations.Seventeen male masters athletes (60 ± 5 years) completed the intervention which comprised of nine HIIT sessions over six weeks. HIIT sessions involved six 30 s sprints at 40% PPO, interspersed with 3 min active recovery. Absolute PPO (799 ± 205 W and 865 ± 211 W) and relative PPO (10.2 ± 2.0 W·kg-1 and 11.0 ± 2.2 W·kg-1) increased from pre- to post-HIIT respectively (P<0.001, Cohen’s d=0.32-0.38). No significant change was observed for total testosterone (15.2 ± 4.2 nmol·l-1 to 16.4 ± 3.3 nmol·l-1 [P=0.061, Cohen’s d=0.32]), whilst a small increase in free testosterone occurred following HIIT (7.0 ± 1.2 ng·dl-1 to 7.5 ± 1.1 ng·dl-1 pre- to post-HIIT [P=0.050, Cohen’s d=0.40]). Six weeks’ HIIT improves PPO in masters athletes and increases free testosterone. Taken together, these data indicate there is a place for carefully timed HIIT epochs in regimes of masters athletes.