The effect of vitamin d deficiency on exercise capacity, respiratory muscle strength, and peripheral muscle strength in patients with connective tissue diseases

Background Vitamin D is one of the fat-soluble vitamins and is also a group of sterols that are hormone and hormone precursors. Vitamin D deficiency and/or insufficiency have been found to be associated with many chronic diseases, including cancers, metabolic syndrome, and autoimmune diseases. Vitamin D is involved in modulation of immune responses in autoimmune disorders including multiple sclerosis, asthma, diabetes mellitus, connective tissue disorders such as rheumatoid arthritis (RA) or systemic lupus erythematosus (SLE). In addition; Previous studies conducted in other patient populations indicate that higher vitamin D levels are related to higher exercise capacity, muscle strength, and better lung function. Objectives The purpose was to investigate the effects of vitamin D deficiency on exercise capacity, respiratory muscle strength, and peripheral muscle strength in patients with connective tissue disease (CTD). Methods This cross-sectional observational study included CDT (SLE and systemic sclerosis (SSc)) patients and healthy participants. Serum 25(OH)D, calcium, and phosphorus levels were measured and Vitamin D levels 10.0-20.0 ng/mL defined insufficiency and levels <10.0 ng/mL defined deficiency. The exercise capacity, respiratory muscle strength, and peripheral muscle strengths were set as the primary outcomes of the study. Secondary outcomes included evaluation of physical activity, dyspnea, pain, emotional status, fatigue, and quality of life. Results There were 23 SLE (36.82±10.06), 21 SSc (44.38±14.63), and 24 healthy controls (37.62±11.74). Compared to healthy controls, CTD groups with vitamin D deficiency had significantly lower respiratory muscle strength (p<0.001), peripheral muscle strength (knee extension and shoulder flexion) (p<0.05), exercise capacity (p<0.05), physical activity (p<0.05), and quality of life (p<0.05) while having significantly more dyspnea (p<0.001), pain (p<0.001), fatigue (p<0.001), anxiety, and depression (p<0.05). Conclusion The results of our study indicate that vitamin D deficiency is associated with reduced muscle strenghts and related symptoms and complaints in CTD patients, hence, in order to increase the efficacy of rehabilitation and treatment programs, attention should be paid to vitamin D levels and should be corrected approprately. References [1]Sizar O, Khare S, Goyal A, Givler A. Vitamin D Deficiency. StatPearls. Treasure Island (FL): StatPearls Publishing. Copyright © 2022, StatPearls Publishing LLC.; 2022. [2]Vaidya B, Nakarmi S. Vitamin D in Rheumatic Diseases: Interpretation and Significance. Fads and Facts about Vitamin D [Internet]. London, United Kingdom: Intech Open; 2019. [3]Hassanalilou T, Khalili L, Ghavamzadeh S, Shokri A, Payahoo L, Bishak YK (2017) Role of vitamin D deficiency in systemic lupus erythematosus incidence and aggravation. Auto Immun Highlights 9(1):1. https://doi.org/10.1007/s13317-017-0101-x . [4]Dawson-Hughes B (2017) Vitamin D and muscle function. J Steroid Biochem Mol Biol 173:313-6. https://doi.org/10.1016/j.jsbmb.2017.03.018 . [5]Ahmed B, Nasir K, Mehmood A, Abid MA, Zehra NA, Khan AH, et al. (2021) Effect of physical activity and vitamin D compared with vitamin D alone on muscle strength, back flexibility and aerobic activity in patients with chronic kidney disease: A comparative study from Pakistan. Asia Pac J Clin Nutr 30(4):566-72. https://doi.org/10.6133/apjcn.202112_30(4).0002 . Acknowledgements: NIL. Disclosure of Interests None Declared.