However, several authors have cited some risks factors for muscle weakening, such as carnitine deficiency, malnutrition, myopathy, muscular atrophy, parathyroid hormone (PTH) excess and toxicity, uremic toxins and vitamin D deficiency.28,29 There is also atrophy of both types of fibers, mainly type II fibers.28 These findings may explain the low adherence to engagement in physical activity. This evidence concerns the gene PTH and vitamin D deficiency.