One session of high-intensity interval training (HIIT) every 5 days, improves muscle power but not static balance in lifelong sedentary ageing men A randomized controlled trial

Abstract

Background: Declining muscle power during advancing age predicts falls and loss of independence. High-intensity interval training (HIIT) may improve muscle power, but remains largely unstudied in ageing participants. Methods: This randomized controlled trial (RCT) investigated the efficacy of a low-frequency HIIT (LfHIIT) intervention on peak muscle power (peak power output [PPO]), body composition, and balance in lifelong sedentary but otherwise healthy males. Methods: Thirty-Three lifelong sedentary ageing men were randomly assigned to either intervention (INT; n=22, age 62.3±4.1 years) or control (n=11, age 61.6±5.0 years) who were both assessed at 3 distinct measurement points (phase A), after 6 weeks of conditioning exercise (phase B), and after 6 weeks of HIIT once every 5 days in INT (phase C), where control remained inactive throughout the study. Results: Static balance remained unaffected, and both absolute and relative PPO were not different between groups at phases A or B, but increased significantly in INT after LfHIIT (P<0.01). Lean body mass displayed a significant interaction (P<0.01) due to an increase in INT between phases B and C (P<0.05). Conclusions: 6 weeks of LfHIIT exercise feasible and effective method to induce clinically relevant improvements in absolute and relative PPO, but does not improve static balance in sedentary ageing men. Abbreviations: ACSM = American College of Sports Medicine, CON = control group, GP = general medical practitioner, HIIT = high-intensity interval training, HRR = heart rate reserve, INT = intervention group, LfHIIT = low-frequency high-intensity interval training, PAR-Q = Physical Activity Readiness Questionnaire, PPO = peak power output, rPPO = relative peak power output, rPPOFFM = rPPO relative to fat free mass, VO2 max = maximal oxygen uptake.