[Metabolic capacity of skeletal muscles and health]

The metabolic capacity of skeletal muscle plays a significant role for insulin sensitivity and the blood lipid profile. The metabolic capacity of the muscle is a function of the individual's physical activity level. This is also true for the content of type IIx muscle fibres, which is reduced and the number of capillaries, which is elevated with muscle usage. Several of these skeletal muscle features are risk factors for or linked with life style-induced diseases such as type II diabetes, hypertension, hyperlipidaemia and obesity. This central role of the skeletal muscle and its functional metabolic capacity for life style diseases highlights the importance of people maintaining daily physical activity. This article focuses on the link between the metabolic capacity of skeletal muscle and the metabolic syndrome and briefly discusses possible metabolic explanations for this relationship. An important aspect is that when skeletal muscle has a high capacity for lipid oxidation more saturated fatty acids are oxidized and more unsaturated fatty acids are built into the phospholipid fraction of the plasma membrane, giving it more fluidity and improved insulin sensitivity. Moreover, the article points at the role of these fatty acids in activating genes via the PPAR-receptor system essential for enzyme and transport proteins in the lipid metabolism.