Effects Of High-intensity Interval Training On Cardiometabolic Indicators Among Older Adults: A Meta-analysis

As a novel and time-efficient exercise form, high-intensity interval training (HIIT) has demonstrated immense potential in enhancing cardiometabolic health across various populations. However, empirical evidence on its efficacy among the elderly has not been well summarized. PURPOSE: This study aimed to meta-analyze the effects of HIIT intervention on older adults’ cardiometabolic indicators, including blood pressure (BP), cardiorespiratory fitness (CRF), body mass index (BMI), body fat percentage (BF%), and waist circumstance (WC), compared to the non-exercise control and other-exercise conditions. METHODS: The literature published between Jan 01, 2000 and May 31, 2023, was comprehensively gathered through extensive searches across eight databases (e.g., PubMed, Web of Science, Scopus, Medline, the Cochrane Library) and relevant review papers. Randomized controlled trials (RCT) featuring a minimum 2-week HIIT intervention for older adults (≥ 60 years) were included. The pooled effect size of Hedge’s g was estimated using random-effects model in R. Meta-regression was performed to identify potential moderators (e.g., mean age, attrition rate, duration and frequency of training program). RESULTS: Forty-four eligible RCT involving 1863 participants (52.1% female; mean age = 60.5-81.2 years) were included in the quantitative analysis. Results revealed that compared to non-exercise condition, HIIT significantly improved older adults’ systolic BP (g = -0.29, 95%CI = [-0.49, -0.10], P = 0.007), CRF (g = 0.76, 95%CI = [0.50, 1.02], P < 0.001), and BF% (g = -0.26, 95%CI = [-0.41, -0.11], P = 0.006). Compared to other exercises, HIIT significantly improved older adults’ systolic BP (g = -0.14, 95%CI = [-0.28, -0.01], P = 0.038), and CRF (g = 0.23, 95%CI = [0.07, 0.38], P = 0.008). No significant differences were found between HIIT and non-exercise control for diastolic BP, BMI, and WC, or between HIIT and other exercises for diastolic BP, BMI, BF%, and WC (all P > 0.05). Meta-regression analysis indicated that mean age and attrition rate moderated the effect of HIIT on systolic BP (b = 0.03, P = 0.048; HIIT vs non-exercise) and CRF (b = 0.03, P = 0.007; HIIT vs non-exercise), respectively. CONCLUSION: HIIT is an effective approach in improving older adults’ systolic BP, CRF, and BF%.