Effect of high-intensity interval training and continuous endurance training on peak oxygen uptake among seniors aged 65 or older: A meta-analysis of randomized controlled trials

Background Ageing is intrinsically associated with a progressive decline in cardiorespiratory fitness (CRF) as measured by peak oxygen uptake (VO2peak). Improving CRF through physical activity contribute to better and healthy ageing. High-intensity interval training (HIIT) is a potent method of improving CRF among seniors, yet comparisons between this type of training and traditional endurance training (ET) are equivocal especially among older adults. Purpose To analyse the effects of HIIT and ET on the VO2peak of seniors aged 65 years or older when compared with controls and also when the two types of training were compared with one another. Methods A comprehensive, systematic database search for manuscripts was performed in Embase, Medline, PubMed Central, ScienceDirect, Scopus and Web of Science using key words. Two reviewers independently assessed interventional studies for potential inclusion. Fifteen randomized controlled trials (RCTs) were included totalling 480 seniors aged 65 years or over. Across the trials, no high risk of bias was measured. Results In pooled analysis of the RCTs, the VO2peak was significantly higher after ET sessions compared with controls (mean difference-MD = 1.35; 95% confidence interval-CI: 0.73-1.96). Furthermore, VO2peak was found significantly higher not only when compared HIIT with controls (MD = 4.61; 95% CI: 3.21-6.01), but also when compared HIIT with ET (MD = 3.76; 95% CI: 2.96-4.56). Conclusion High-intensity interval training and ET both elicit large improvements in the VO2peak of older adults aged 65 or over. When compared with ET, the gain in VO2peak was greater following HIIT. Nevertheless, further RCTs are therefore needed to confirm our results in senior's population.