The evaluation of skeletal muscle strength in severly ill or cognitive impaired patients is an unresolved problem especially during the rehabilitation process. The aim of this study is to correlate morphological parameters assessed with muscle ultrasound and isometric muscle strength to establish an objective progression parameter for rehabilitation therapies.

Inclusion Criteria:

• group 1: patients between 18 and 35 years
• group 2: patients between 60 and 80 years

Exclusion Criteria:

• neuromuscular diseases
• hip or knee prosthesis in the investigated leg
• any trauma of the hip, knee or ankle of the investigated leg during the last 12 months
• cognitive impairments
• pregnancy
• diabetes mellitus Type II
• acute or chronic pain in the investigated leg
• chronic maligne or non - maligne diseases (of the heart, lung or kidney)

outpatients or inpatients of the institute of physical medicine and rehabilitaion