Sarcopenia is a very common, but frequently overlooked and undertreated geriatric syndrome comprising pronounced muscle mass and strength/performance loss. Estimated prevalence is between 5 and 40% in the general population, accompanied by an exponential incline with increasing age. Sarcopenia is connected to atrophy and loss of muscle fibers and motor units, affecting primarily the fast-twitch muscle fibers und their motor units. Fast-twitch muscle fibers seem to be more prone to failure of function and loss over time. Main causes for the development of sarcopenia are hormonal changes (reduced release of testosterone, estrogen, and growth hormone), nutritional deficiencies, chronic inflammation, and particularly a decrease in physical activity due to sedentary lifestyle with advancing age. Treatment options for sarcopenia comprise an active lifestyle with physical activity and exercise training, modifications of nutritional intake, and pharmacological therapies. Strength training and an adequate nutritional intake form the basis of successful sarcopenia treatment.