Sarcopenia - pathophysiology and clinical relevance.

The causes of sarcopenia are multidimensional. The loss of fast-twitch muscle fibres exceeds the loss of slow-twitch muscle fibres and ends as a clinical relevant loss of muscle power. On a sub-cellular level, age associated changes in the mitochondria lead to functional decline of the muscle. The reduction of motor units causes muscle fibre atrophy and loss of muscle strength. Low levels of anabolic hormones and the imbalance of pro- and anti-inflammatory cytokines are responsible for changes in body composition of older adults. Reduced levels of physical activity, vitamin D and protein are highly associated with muscle loss. Sarcopenia causes loss of independence and high medical and nursing needs resulting in great economic healthcare burden.