Prolonged recovery to a single bout of high intensity interval training in ageing men

While the optimal frequency of HIIT remains unresolved in both young and ageing cohorts, there are currently no data available regarding recovery rates from HIIT in older participants. PURPOSE: To compare recovery time, from a single HIIT session, in older and younger men. METHODS: Following approval from the Institutional Ethics Committee at the University of the West of Scotland, 10 older (age=63±3.4yrs; height=1.74±0.04m mass=79.58±9.2kg) and 10 younger (21±2yrs; height 1.77±0.05; mass=81.0±10.7kg) apparently healthy males provided written informed consent to participate in the study. The study employed a parallel crossover RCT design. All participants were initially evaluated for PPO (Baseline) and performed a single HIIT session on the same day and were randomly assigned to either 3 days (3DR) or 5 days (5DR) of recovery before PPO reassessment. Seven days following the PPO reassessment, participants undertook a second, identical HIIT session, and crossed over to the opposing arm of the trial. PPO was assessed on a Wattbike Pro (Wattbike Ltd Nottingham, UK) cycle ergometer using a test that has been validated against PPO achieved during a standard Wingate test and described previously. HIIT sessions consisted of 6 x 30 s sprints at 50% of PPO determined at Baseline. Each 30 s effort was interspersed with 3 mins of active recovery against a low (0-50W) resistance and at a self-selected cadence. RESULTS: There was a significant effect of recovery time (P<0.01) and of age group (P<0.01) and a significant interaction between the two (P<0.01). Between groups, the younger group generated greater PPO at all-time points compared with the older cohort (Baseline= 852±102 versus 1171±247W, 3DR= 814±88 versus 1181±256W and 5DR= 861±104 versus 1182±259W for old versus young respectively; all P<0.01). Compared with baseline, the older group experienced a significant reduction in PPO at 3DR (P<0.01), which was not evident at 5DR (P>0.05), whereas PPO remained unchanged in the young group between baseline and 3DR and 5DR (P>0.05 for all comparisons). CONCLUSION: Older men require longer than 3 days to recover from a single bout of HIIT and the present study promotes the exercising of caution when prescribing standard HIIT regimens (3.session.week-1) to older persons.