Vaes AMM, et al. - In this cross-sectional study, researchers determined the association of serum 25-hydroxyvitamin D (25(OH)D) concentration with physical performance and frailty status in Dutch older adults, using multiple linear regression and prevalence ratios (PR). They measured the Timed Up and Go test (TUG) and knee-extension strength in a subgroup. Vitamin D decficiency was detected in 45% of the participants. Serum 25(OH)D concentrations were found to be significantly related to frailty status and measures of physical performance, including gait speed and TUG, but no association with strength-related outcomes was found.