Effect of Vitamin D supplementation on aerobic exercise performance in healthy adults; a randomised single blinded placebo controlled pilot study

Abstract

Background: 1,25-dihydroxyvitamin D (1,25(OH)D), the biologically active form of vitamin D, is thought to be directly related to exercise induced inflammation and skeletal muscle performance and deficiency has catabolic effects on muscle tissue, causes muscle weakness and impairs cross-bridge formation. 1,25(OH)D may also affect cardiovascular risk factors such as blood pressure (BP), which in turn may have an effect on aerobic exercise; however, at present evidence investigating this association are lacking. Therefore,the aim of this study was to investigate the effect of vitamin D supplementation on aerobic exercise following two weeks of intervention. Methods: A randomised placebo controlled single-blinded pilot study aimed to investigate the short term effects of vitamin D supplementation on aerobic exercise performance in a group of healthy adults. Eleven healthy adults were allocated to receive either 2000IU (50_g/day) of vitamin D or a placebo (sucrose) for 14 days. Physical activity and diet diaries were completed throughout the study. Aerobic exercise performance was assessed at baseline and day 14 following a 15-minute run on a treadmill set at a gradient of 1.5%. Height, weight, systolic/diastolic BP and heart rate (HR) were recorded at baseline and day 14 before running. Parameters of aerobic exercise exertion (BP, %HR and difference in blood lactate) were recorded before and after each run. The rate of perceived exertion (RPE) was recorded after each run. Results: HR reduced significantly by 2.5% (p = 0.002) from 91.5 4.5% to 89.0 3.7% in the intervention group, but not in the placebo group (1.2%; 87.8 4.5% to 86.6 5.1%. p = 0.4). The difference in blood lactate between pre and post run was smaller in the intervention group [(3.9 3.7 mmol/L; p = 0.2 SEM (1.5)] than in the placebo group [(5.5 3.8 mmol/L; p = 0.1; SEM (5.9)]; however,this did not statistically differ between [p = 0.5; SEM (2.2)] and within the groups. Finally, a statistically significant reduction [(p = 0.001; SEM (0.7)] in RPE was found in the intervention group only (15.8 1.9 to 14.7 2.2). Conclusion: The significant reduction in both percentage heart rate and rate of perceived exertion found in this study over a two week period suggest that short term vitamin D supplementation may improve aerobic exercise performance. However, larger scale studies are now warranted to verify these findings.