During the last decades there has been an increase in the relative proportion and life expectancy of elderly people in the industrialised countries. Consequently the amount of elderly with diseases and disabilities related to aging has increased. It therefore appears paramount to gain a better understanding of how disuse and immobilisation affects neuromuscular properties in the elderly, as well as to identify training regimes that ensures an effective rehabilitation.The population of interest in the present study was elderly individuals with long term hip-osteoarthritis undergoing a hip-replacement operation. The study was divided in two parts, a cross-sectional study and an intervention study.