The impact of high-intensity interval training interventions on adult's bone mineral density and bone turnover markers: A systematic review and meta-analysis

Background: High-intensity interval training (HIIT) is a highly beneficial exercise training for significantly increasing cardiovascular fitness in individuals; however, few studies have explored its potential benefit on bone health. This systematic review aimed to assess the evidence of the effectiveness of HIIT on bone health in adult. Method: Seven electronic databases (PubMed, EMBASE, Medline, PsycINFO, SPORTDiscus, Web of Science, Scopus, and Cochrane Central Register of Controlled Trials [CENTRAL]) were searched till March 2025 using predefined terms. Studies published in English were included if they met the following criteria: the mean age of participants was 18years or older; the intervention protocol included at least one group performing HIIT intervention; comparator was another exercise intervention group or non-exercise control group; outcomes contained bone mineral density (BMD) or bone turnover markers (BTMs). The pooled effect size of Hedge's g was estimated using random-effects models in R. Meta-regression was performed for both categorical (menopausal status, duration of training programme, and frequency) and continuous moderators (mean age, female rate). Results: Nine eligible RCTs with 247 participants (88.7% female; 21.9–65.0years) were included in the quantitative analysis. The pooled effect size of total body BMD (g=0.309, 95% CI=−0.237, 0.892) and other sites of BMD showed insignificant difference between HIIT group and non-exercise control group. However, the results of meta-regression analysis indicated that HIIT demonstrated a greater significant effect on BMD (especially for lumbar spine and femoral neck) for postmenopausal women (g=0.933, 95% CI=[0.398, 1.227]). Additionally, the pooled effect size of bone formation BTMs and bone resorption BTMs also showed insignificant difference between HIIT group and non-exercise control group. Conclusion: While the HIIT intervention did not demonstrate a significant overall effect on BMD and BTMs, it shows promise for improving bone health in postmenopausal women with conditions like osteopenia or osteoporosis. Future studies in this area should employ more reliable and valid research methods to enhance the quality of evidence, allowing for more definitive conclusions.