Abstract Context Vitamin D is implicated in cardiorespiratory fitness (CRF) through its roles in skeletal muscle metabolism and vascular function. Despite numerous studies linking vitamin D to CRF, no comprehensive meta-analysis has quantified their overall correlation or the effect of vitamin D interventions. Objective The objective of this review was to investigate any association between vitamin D concentration and CRF, and the effect of vitamin D supplementation on CRF. Data Sources PubMed, Embase, and Web of Science were systematically searched from their inception to November 2024. Data Extraction A total of 20 observational studies (14 554 participants) and 9 interventional studies (733 participants) were included in the meta-analysis. Data Analysis The effect size, correlation coefficient r, and a 95% CI (CI) were employed to estimate the correlation between vitamin D concentration and CRF. A random-effects model was used to calculate the standardized mean differences (SMDs) and 95% CIs. A significantly positive yet weak association (r = 0.17; 95% CI: 0.11, 0.24; P .0001) was found between vitamin D concentration and CRF, with high heterogeneity (I2 = 88.0%, P heterogeneity .0001). The correlation coefficient in children (r = 0.05; 95% CI: 0.01, 0.09; P = .0273) was smaller than that in adults (r = 0.26; 95% CI: 0.17, 0.34; P .0001) (Psubgroup .0001). No significant differences were observed between study subgroups stratified by gender, CRF measurement method, vitamin D assays, or physical activity level (all Psubgroup .05). Interventional studies revealed that the effect of vitamin D supplementation on CRF is not significant (SMD: 0.03; 95% CI: −0.12, 0.17; P = .8959), with 0% heterogeneity. Conclusion This meta-analysis confirms there is a small but significant positive relationship between vitamin D concentrations and CRF, especially in adults. However, the studies found no improvement in CRF through vitamin D supplementation in interventional trials. Systematic Review Registration PROSPERO registration No. CRD42024574603.
Chen et al. (Tue,) studied this question.