[The concept of frailty--from phenomenology to therapeutic approaches].

Frailty--the weakness of many (oldest) old persons--induces a lot of human sorrow with functional disabilities as well as health-economic costs. Sarcopenia (loss of muscle mass) is also a form of frailty and a co-factor of two of the "geriatric Is"--immobility and instability. Pathophysiologically, both phenomena show signs of an inflammatory state. Physical activity and a healthy diet can partially reverse these health problems. Therefore, therapeutic strategies emerge to treat these frequent and clinically relevant phenomena.