25(OH) Vitamin D Is Associated with Greater Muscle Strength in Healthy Men and Women

GRIMALDI, A. S., B. A. PARKER, J. A. CAPIZZI, P. M. CLARKSON, L. S. PESCATELLO, M. C. WHITE, and P. D. THOMPSON. 25(OH) Vitamin D Is Associated with Greater Muscle Strength in Healthy Men and Women. Med. Sci. Sports Exerc., Vol. 45, No. 1, pp. 157-162, 2013. Purpose: The purpose of the study was to examine the relation between serum 25-hydroxy vitamin D (25(OH)D) levels and muscle strength in 419 healthy men and women over a broad age range (20-76 yr). Methods: Isometric and isokinetic strength of the arms and legs was measured using computerized dynamometry, and its relation to vitamin D was tested in multivariate models controlling for age, gender, resting HR, systolic blood pressure, diastolic blood pressure, body mass index, maximal oxygen uptake ((V) over dotO(2max),), physical activity counts, and season of vitamin D measurement. Results: Vitamin D was significantly associated with arm and leg muscle strength when controlling for age and gender. When controlling for other covariates listed previously, vitamin D remained directly related to both isometric and isokinetic arm strength but only to isometric leg strength. Conclusion: These data suggest that there may be a differential effect of vitamin D on upper and lower body strength. The mechanism for this difference remains unclear but could be related to differences in androgenic effects or to differences in vitamin D receptor expression. Our study supports a direct relation between vitamin D and muscle strength and suggests that vitamin D supplementation be evaluated to determine whether it is an effective therapy to preserve muscle strength in adults.