Comparison Of High And Low 25(OH)-Vitamin D Concentrations On Recovery From Resistance Exercise In Men: 3004 Board #1 June 2 3

BACKGROUND: Vitamin D status (VITD) has been related to impaired skeletal muscle function, and may be associated with recovery after muscle injury. Limited data exists on the relationship between VITD concentrations, muscle damage and inflammatory markers from an acute bout of exercise. PURPOSE: Examine the effect of VITD concentrations on acute physiological responses and recovery indices from resistance exercise. METHODS: 15 resistance trained men (24±4 y) with at least 2 years of resistance training experience volunteered to participate in this study. Participants were grouped into a low 25(OH)-VITD (LVD; 26.7±1.7 ng·ml-1; n=7) or high 25(OH)-VITD (HVD; 37.2±7.2 ng·ml-1; n=8) group based upon baseline (BL) 25(OH)-VITD concentrations. Participants performed 8 sets of 10-12 repetitions at 70% of the maximal strength of the squat exercise, with 75 s of rest between sets. Performance [counter movement jump (CMJP), endocrine (testosterone [T] and cortisol [C]), inflammatory (IL-6 and C-reactive protein [CRP]), and muscle damage (creatine kinase [CK] and myoglobin [MB]) assessments were performed at BL, 30-min, 24-h, 48-h and 72-h post-exercise. Data was analyzed using a repeated measures ANOVA. To complement this procedure, magnitude based inferences were used to provide additional interpretation of the differences that VITD concentrations may have had on the recovery response. RESULTS: No significant interactions were noted between LVD and HVD in CMJP (p=0.26), C (p=0.97), T (p=0.21), CRP (p=0.30), IL-6 (p=0.58) or CK (p=0.16) responses to the exercise protocol. However, a significant interaction was observed in MB (p=0.05) responses. Although post-hoc analyses failed to see any significant differences between the groups at any time point, inferential analysis indicated that MB concentrations was “likely” higher at 30-min for LVD (87.2±57.4 ng·ml-1) than HVD (51.3±21.9 ng·ml-1). CRP levels were “likely” lower at 24-h (549±373 mg·L-1 vs.1344±1654 mg·L-1) and 48-h (565±386 mg·L-1 vs.1079±1077 mg·L-1) for HVD. Inferences for all other comparisons were unclear. CONCLUSIONS: Results indicated that HVD provides a degree of resiliency towards acute muscle damage and enhances recovery of high velocity resistance exercise compared to LVD. Further research using greater sample size appears warranted.