Background:​ Osteoporosis and sarcopenia are prevalent in older adults. Trabecular bone score (TBS) is a novel method to evaluate bone microarchitecture, whereas grip strength and gait speed are simple methods to assess muscle strength and function. Few studies have linked the relationship between vitamin D levels (25OHD) with TBS, grip strength, and gait speed in healthy community dwelling adults. We sought to investigate this relationship in older women with osteoporosis and multiple comorbid conditions residing in long-term care (LTC) facilities.

Methods:​ We analyzed baseline 25OHD, spine TBS, grip strength, and gait speed in 246 women with osteoporosis who were residents of LTC and enrolled in a randomized controlled clinical trial.

Results:​ On average, participants were 81.6 years old and had a BMI of 26.8 kg/m2. The correlation (r) of 25OHD with spine TBS, grip strength, and gait speed were (r = 0.15;​ p = 0.0208), (r = − 0.05;​ p = 0.4686), and (r = 0.19;​ p = 0.0041), respectively. Each 5 ng/dl increase in 25OHD was associated with an increase of 0.006 in spine TBS and 0.014 m/s in gait speed. After adjusting for covariates, each 5 ng/dl increase in 25OHD was associated with an increase of 0.004 in spine TBS (p = 0.0599) and 0.012 m/s in gait speed (p = 0.0144).

Conclusion:​ In older women residing in LTC facilities, 25OHD was associated with spine TBS and gait speed. The strengths of the associations suggest there may be other factors with a more prominent role in bone microarchitecture, muscle strength, and physical function in this population.

Mini abstract:​ Our study found in older women who are residents of long-term care facilities, vitamin D level is associated with bone microarchitecture and mobility performance.