Association between vitamin D status and physical performance : the InCHIANTI study

BACKGROUND: Vitamin D status has been hypothesized to play a role in musculoskeletal function. Using data from the InCHIANTI study, we examined the association between vitamin D status and physical performance. METHODS: A representative sample of 976 persons aged 65 years or older at study baseline were included. Physical performance was assessed using a short physical performance battery (SPPB) and handgrip strength. Multiple linear regression was used to examine the association between vitamin D (serum 25OHD), parathyroid hormone (PTH), and physical performance adjusting for sociodemographic variables, behavioral characteristics, body mass index, season, cognition, health conditions, creatinine, hemoglobin, and albumin. RESULTS: Approximately 28.8% of women and 13.6% of men had vitamin D levels indicative of deficiency (serum 25OHD < 25.0 nmol/L) and 74.9% of women and 51.0% of men had vitamin D levels indicative of vitamin D insufficiency (serum 25OHD < 50.0 nmol/L). Vitamin D levels were significantly associated with SPPB score in men (beta coefficient [standard error (SE)]: 0.38 [0.18], p =.04) and handgrip strength in men (2.44 [0.84], p =.004) and women (1.33 [0.53], p =.01). Men and women with serum 25OHD < 25.0 nmol/L had significantly lower SPPB scores whereas those with serum 25OHD < 50 nmol/L had significantly lower handgrip strength than those with serum 25OHD > or =25 and > or =50 nmol/L, respectively (p <.05). PTH was significantly associated with handgrip strength only (p =.01). CONCLUSIONS: Vitamin D status was inversely associated with poor physical performance. Given the high prevalence of vitamin D deficiency in older populations, additional studies examining the association between vitamin D status and physical function are needed.