J Bone Miner Res. 2020 Feb 20. Epub 2020 Feb 20. PMID: 32078180
Exercise may ameliorate the detrimental side effects of high vitamin D supplementation on muscle function in mice.
Vitamin D (VitD) is commonly prescribed to normalise deficiencies and to treat osteoporosis. However, the effect VitD supplements have on skeletal muscle health is equivocal. While VitD is known to play a role in the various processes that maintain muscle integrity and function, recent studies utilising high bolus dose VitD supplementation has demonstrated an increased risk of falls. Thus, the aim of this study was to investigate the effects of high VitD supplementation on skeletal muscle function with and without exercise enrichment. Four-week old C57BL/10 mice (n = 48) were separated into either normal VitD (1500 IU/kg diet; unsupplemented) or high VitD (20,000 IU/kg diet; supplemented) treatment groups. Each dietary group was further separated into interventional sub-groups where mice either remained sedentary or received exercise-enrichment for eight weeks in the form of voluntary running. Following the intervention period, whole body in vivo and ex vivo contractile analysis were performed. High VitD supplementation decreased force production in the slow-twitch soleus muscles of sedentary mice (p