HIIT vs. MICT to Improve Cardiorespiratory Fitness and Exercise Capacity in Older Adult

Previous studies have shown that High-Intensity Interval Training (HIIT) is effective in improving maximal oxygen uptake, blood pressure, and physical health-related indicators in older adults. However, whether HIIT is more effective in improving cardiorespiratory fitness and exercise capacity in older adults compared with Moderate-Intensity Continuous Exercise (MICT) remains controversial. This review and META analysis assessed the outcomes associated with HIIT on cardiorespiratory fitness and exercise capacity in older adults by searching five electronic databases (PubMed, Embase, SPORTDiscus, Scopus, and Cochrane Library) (built to July 2022). Relevant studies were included using the Cochrane Risk of Bias Assessment Tool; statistical analyses were performed using REVMAN software. HIIT significantly improved VO 2max (HIIT vs. MICT) (weighted mean difference = 1.80, 95% confidence interval: 1.25-2.35, p < 0.001) and maximal heart rate, ventilation maximal power output compared to the MICT protocol. Subgroup analysis determined that training period < 12 weeks, training frequency three times/week, 20 min per intervention, < 80% intensity VO 2 peak, 3 repetitions, < 60s per training session, and ≤ 90s rest time had the greatest effect on VO 2 max. Compared with MICT, HIIT was more effective in improving cardiorespiratory fitness and exercise capacity in older adults.