Based on studies included in this systematic review, vitamin D supplementation does not have a significant effect on muscle strength in adults with baseline 25(OH)D >25 nmol/L. However, a limited number of studies demonstrate an increase in proximal muscle strength in adults with vitamin D deficiency.
Recent studies have demonstrated an inverse relationship between vitamin D levels and fatigue in systemic lupus erythematosus (SLE). The aims of this study were to evaluate proximal muscle strength, fatigue and vitamin D levels in women with SLE compared with healthy controls and to investigate relationships between these factors in a cohort of women with SLE. Forty-five women (24 SLE, 21 healthy controls) participated. Primary outcome measures were the fatigue severity scale (FSS), isometric muscle strength of dominant limbs using hand held dynamometry, two functional tests--the 30-second chair stand test and the 1-kg arm lift test, with vitamin D status measured using 25(OH)D. Overall 25(OH)D levels were 68.4 (22.4) nmol/L with no difference between SLE and control groups. There was a statistically and clinically significant difference in fatigue, 1-kg arm lift, 30-second sit to stand, knee extension, hip flexion, hip abduction, shoulder flexion and grip strength in the SLE group compared with the control group (p < 0.05). In the SLE group FSS was moderately correlated with both functional measures (1-kg arm lift r = -0.42, 30-second chair stand r = -0.44, p < 0.05). However, no statistically significant correlation between dynamometry measures and fatigue was evident. There was no association between fatigue and 25(OH)D level (r = -0.12). In summary, women with SLE were weaker and demonstrated reduced physical function and higher fatigue levels than healthy controls. Fatigue was related to physical function but not vitamin D status or maximal isometric strength in vitamin D replete individuals with SLE.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.