Muscle function is of importance for physical function, autonomy and quality of life. Adequate nutrition with focus on protein, vitamin D and resistance training is prerequisite for of muscle mass and function. Sarcopenia is defined as loss of muscle mass and strength, associated with aging and linked to functional impairment with increased risk of falls. Sarcopenic subjects are vulnerable to metabolic stress since muscle protein is mobilized to provide amino acids for the metabolism. Sarcopenia is an essential component of physical frailty a geriatric syndrome of decreased reserve capacity and resistance to stressors, resulting from declines across multiple physiologic systems, causing vulnerability to adverse health outcomes.