Modulation Of Acute Metabolic And Inflammatory Responses To Resistance Exercise By Vitamin D3 Injection In Vitamin D-deficient Males

Abstract

Vitamin D deficiency has been previously associated with impaired metabolic functions which may impact the acute effects of resistance exercise (RE) on insulin sensitivity, inflammation, and muscle damage. The effects of exogenous vitamin D on the metabolic, inflammatory, and muscle damage responses to an acute bout of RE in vitamin D deficient subjects have yet to be explored. PURPOSE: To evaluate the effects of a single vitamin D3 injection on the metabolic, inflammatory and muscle damage responses to an acute bout of RE in vitamin D-deficient resistance-trained males. METHODS: Blood samples from 14 vitamin D-deficient resistance-trained males were obtained during two separate trials: lower vitamin D (LVD, after saline injection) and higher vitamin D (HVD, after vitamin D3 injection). Metabolic, inflammatory, and muscle damage markers were evaluated at baseline and immediately then one hour after RE. Differences in mean values for each variable between trials were compared by repeated measures ANOVA followed by LSD test for pairwise comparisons. RESULTS: There were significant trial x time interactions for serum insulin and Homeostatic Model Assessment (HOMA) of Insulin Resistance which were both lower (p˂0.05) at 1-hour post-RE in the HVD compared to LVD trial. There was a significant decrease (p<0.05) for blood sugar and increase (p<0.05) for creatine kinase, lactate dehydrogenase, and interleukin 6 1-hour post-RE across both trials with no interaction of time. There were no significant changes in other inflammatory and cardiovascular markers following either trials. A single injection of vitamin D3 demonstrated efficacy in reducing insulin resistance following RE in previously vitamin D-deficient resistance-trained males. Conversely, muscle damage and inflammatory response to acute RE were not altered. CONCLUSION: Intramuscular vitamin D replacement in vitamin D-deficient resistance-trained males may have key implications for the promotion of glucose metabolism and lowering the risk of diabetes in this population.