The investigators have taken part in the development of simple muscle function tests and studied physical training and energy turnover in patients with chronic obstructive pulmonary disease, COPD. The investigators have found that muscle wasting in COPD is related to poor prognosis and that physical training might lead to improved, less energy-demanding muscle function. Elderly subjects also suffer from muscle wasting that leads to frailty, poor autonomy and, secondarily, fractures. In the planned study the investigators will validate simple muscle function tests (hand grip strength, heel rise test, voluntary quadriceps muscle strength, 30 m walking test and balance tests) in both groups by relating them to an involuntary, magnet stimulated, test of quadriceps force, HRQL, tests of body composition (impedance, DXA) and recordings of physical activity. The relation between food intake, systemic inflammation, muscle mass and function will be analysed.