The effect of high-intensity interval training and moderate-intensity continuous training on cardiorespiratory function in healthy elderly individuals: Systematic review and meta-analysis

BACKGROUND: This study aims to systematically evaluate the intervention effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on cardiovascular and pulmonary functions in healthy elderly individuals, providing evidence-based recommendations for the development of exercise prescriptions for this population. METHODS: A systematic search was conducted in the PubMed, Web of Science, Cochrane Library, and Google Scholar databases (through March 2025) to identify randomized controlled trials that investigated the effects of HIIT and MICT on cardiovascular and pulmonary functions in elderly individuals. Data were analyzed using RevMan 5.4 and Stata 15.1, employing a random-effects model to calculate the pooled effect size (weighted mean difference) and its 95% confidence interval (95% CI) for maximal oxygen uptake. RESULTS: A total of 16 studies (n = 1434) were included. In the MICT group (12 studies), maximal oxygen uptake levels were significantly improved (mean difference [MD] = 1.22, 95% CI: 0.90-1.53). In the HIIT group (11 studies), the improvement was more pronounced (MD = 1.62, 95% CI: 1.10-2.13). In studies that included both HIIT and MICT (7 studies), HIIT demonstrated significantly superior improvements compared to MICT (MD = 1.17, 95% CI: 0.52-1.82). Subgroup analysis revealed that the optimal MICT protocol consisted of a moderate duration (>3 months and 3 months and