Volume 63, Issue 4 p. 817-818
Letters to the Editor
Free Access

Exercising Caution: Prolonged Recovery from a Single Session of High-Intensity Interval Training in Older Men

Peter Herbert MA

Peter Herbert MA

University of Wales Trinity Saint David, Carmarthen Campus, Carmarthen, UK

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Fergal M. Grace PhD

Fergal M. Grace PhD

Institute of Clinical Exercise & Health Sciences, University of the West of Scotland, Hamilton, South Lanarkshire, UK

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Nicholas F. Sculthorpe PhD

Nicholas F. Sculthorpe PhD

Institute of Clinical Exercise & Health Sciences, University of the West of Scotland, Hamilton, South Lanarkshire, UK

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First published: 20 April 2015
Citations: 23

To the Editor: We read with interest the recent article by Adamson et al.,1 which reports positive outcomes after high-intensity interval training (HIIT) in a small sample of older adults. Improvements were achieved after twice-weekly HIIT sessions over 6 weeks using a method loosely based on a thrice-weekly HIIT protocol in young obese participants.2 There are no data available regarding recovery rates from HIIT in older participants. Previous work has indicated that older men require a longer recovery from resistance exercise than younger men,3 and this recovery may exceed 5 days.4 Although the optimal frequency of HIIT remains unresolved in younger and older individuals, the implementation of identical training frequencies assumes that both groups experience equivalent recovery between bouts, yet no studies have investigated time to recovery from a single HIIT session. Such information should form the basis of effective, age-specific HIIT programs. Therefore, the present study compared recovery time from a single HIIT session in older and younger men.

After approval was received from the institutional ethics committee at the University of the West of Scotland, 10 older (aged 63 ± 3.4, height 1.74 ± 0.04 m, weight 79.6 ± 9.2 kg) and 10 younger (aged 21 ± 2.1, height 1.77 ± 0.05 m, weight 81.0 ± 10.7 kg) apparently healthy men provided written informed consent to participate in the study. All participants were engaged in structured exercise training programs, and five were international masters athletes. After medical screening, participants were enrolled in the study and undertook two familiarization sessions to acquaint them with the peak power output (PPO) and HIIT protocols. Participants were instructed to refrain from their usual training for the duration of the study. The study used a parallel crossover randomized controlled design. All participants were initially evaluated for PPO (baseline), performed a single HIIT session on the same day, and were randomly assigned to 3 (3DR) or 5 (5DR) days of recovery before PPO reassessment. Seven days after the PPO reassessment, participants undertook a second, identical HIIT session and crossed over to the opposing arm of the trial. Complete cohort data for each group at baseline, 3DR, and 5DR were used for statistical analysis using a two-by-three mixed-design analysis of variance with Bonferroni-corrected pairwise comparisons and α set to P ≤ .05. 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.5 HIIT sessions consisted of six 30-second sprints at 50% of PPO determined at baseline. Each 30-second effort was interspersed with 3 minutes of active recovery against a low (0–50 W) resistance and at a self-selected cadence. All sessions were performed on a Wattbike Pro cycle ergometer.

There was a significant effect of recovery time (P < .001) and of age group (P = .001) and a significant interaction between the two (P < .001). The younger group generated greater PPO at all time points than the older cohort (baseline 1,171 ± 247 vs 852 ± 102 W, P = .002; 3DR 1,181 ± 256 vs 814 ± 88 W, P < .001; 5DR 1,182 ± 259 vs 861 ± 104 W; P = .002 for all comparisons). The older group experienced a significant reduction in PPO from baseline to 3DR (P = .001) that was not evident at 5DR (P = .17), whereas PPO remained unchanged in the young group between baseline and 3DR (P = .85) and 5DR (P = .07) (Figure 1).

Details are in the caption following the image
Peak power output for older and younger participants at baseline (BASE), and after 3 (3DR) or 5 (5DR) days of recovery. *P < .01 versus younger at the same time point. P < .01 versus abaseline, versus c5DR.

The findings of the present study indicate that, in young trained men, 3 days was sufficient for complete recovery of peak muscle power, whereas in their older counterparts, 3 days was insufficient to achieve full recovery of PPO. Furthermore, the current cohorts were athletically trained, and it is plausible that less-well-trained or long-term sedentary older individuals may experience even greater deficits in PPO after a single bout of HIIT. It has been suggested that older individuals take longer to recover from strenuous resistance exercise than their younger counterparts3 and that their recovery from muscle soreness can exceed 5 days.4 Despite this and the recent emergence of HIIT as an effective exercise mode, there are no previous reports of recovery rates from HIIT in older, apparently healthy individuals. The present findings indicate that failure to consider optimal recovery times when programming HIIT, risks exposing older individuals to accumulating fatigue and potentially hampering exercise adherence and tolerance.

In conclusion, the present data indicate that older men require longer than 3 days to recover from a single bout of HIIT and that care should be taken when prescribing HIIT regimens to older persons.

Acknowledgments

The authors would like to thank all participants who took part in the study.

Conflict of Interest: None.

Author Contributions: Sculthorpe, Grace, Herbert: study design. Herbert: data collection, manuscript preparation. Sculthorpe, Grace: data analysis, manuscript preparation.

Sponsor's Role: None.