Low frequency HIIT improves peak power and body composition in sedentary healthy older men

Ageing is associated with a decline in muscle peak power output (PPO), muscle mass and proprioceptive balance. Furthermore, in ageing individuals low PPO is highly predictive of future falls and dependence. Low volume high intensity interval training (HIIT) has been demonstrated as an effective and time efficient method of improving PPO in healthy young individuals. Recent evidence indicates that older individuals require longer recovery following a single bout of HIIT than younger counterparts. Consequently low training volumes achieved by reduced frequency of training (low frequency HIIT; LfHIIT) may be a suitable protocol for the maintenance of PPO in older individuals. There are currently no randomised controlled trials (RCT’s) of low volume or low frequency HIIT in sedentary but otherwise healthy older adults.
PURPOSE: To determine the efficacy of LfHIIT following general conditioning on PPO, lean muscle mass and balance in lifelong sedentary older adults.
METHODS: Following institutional ethical approval and using an RCT design, 31 lifelong sedentary older males where allocated to intervention (INT; n= 21, age=62.7±5.2yrs) or control (CON; n=10, age=64.1±4.0 yrs) groups. INT underwent 6 weeks of conditioning in line with the ACSM guidelines, followed by a further 6 weeks of LfHIIT comprising of one session every 5 days. Both INT and CON were assessed for PPO, anthropometrics and balance on enrolment to the study (Phase A), following 6 weeks of conditioning exercise (Phase B) and following 6 weeks of LfHIIT training (Phase C). Data were analysed using a 2x3 mixed design ANOVA with post-hoc Bonferonni corrected pairwise comparisons.
RESULTS: General conditioning had no effect of PPO or relative PPO (rPPO) in INT (P>0.05 for all comparisons). LfHIIT resulted in significant increases in both PPO (706.5±173.8 W to 831.1± 170.6W; P<0.01) and rPPO (8.1± 1.7 to 9.5±1.8 W.kg-1; P<0.01). LfHIIT also resulted in a significant increase in LBM (66.1±6.6 to 68.1±7.5 P<0.05). There were no effects on balance either in CON or INT (P>0.05 for all comparisons).
CONCLUSION: Despite a low total effort time and training frequency, LfHIIT is effective at improving PPO and rPPO in lifelong sedentary older males. In addition there were favourable changes in body composition, but balance was not affected by conditioning or LfHIIT.