Association of vitamin D deficiency with muscle strength and quality of life in postmenopausal women

Aim The aim of this study was to analyze the effect of vitamin D deficiency on muscle strength and quality of life in postmenopausal women. Methods Self-sufficient, community-dwelling, postmenopausal women over 55 years old attending the Physical Medicine and Rehabilitation outpatient clinic were included in the study. 25-Hydroxyvitamin D levels below 20 ng/ml were accepted as indicative of vitamin D deficiency. A computerized isokinetic dynamometer (Cybex 770 Norm, Lumex Inc., Ronkonkoma, NY, USA) was used for testing knee extensor muscle strength. Results Forty-nine postmenopausal women with median age 64.3 years (interquartile range 59.0-69.5 years) were included in the study. Vitamin D deficiency was detected in 49% of the participants. There was no relation between vitamin D deficiency and knee muscle strength in both right and left legs. Vitamin D deficiency was found not to be associated with any of the domains of SF-36. Conclusions Vitamin D deficiency is not related to decreased muscle strength and lowered quality of life in postmenopausal women. Other factors rather than vitamin D deficiency should be investigated for illuminating the causalities of these two common clinical conditions.