[Structure and function of skeletal muscles].

Abstract

This review describes the structural make-up of muscle cells in term of the organization of the main myo-proteins into sarcomeres. The activation of muscle contraction is discussed on the cellular level as well as an integrative problem of activation of motor units for motor task. In this context the discrimination of muscle fibers into slow and fast types plays a role in particular with regard to specific athletic qualities. The energy supply systems present themselves as a sequence of distinct processes, which are responsible for power output for seconds, (phosphocreatine), minutes (glycolysis) and minutes to hours (oxidative phosphorylation). The supply of oxygen is a limiting condition for continued muscle work as the body does not maintain sizeable stores of oxygen. By contrast substrates (both carbohydrates and lipids) are stored in myocytes as well as systemically and do therefore not represent immediate limits to exercise performance.