From “sliding” to “winding” filaments theory: A narrative review of mechanisms behind skeletal muscle contraction

The physiological mechanisms behind muscle contraction are a main concept in sport medicine andrehabilitation. The sarcomere is the functional unit of skeletal muscle and several proteins definite its complexstructure. The most common theory to explain muscle contraction was proposed in the last 50’s and hasbecome widely popular and accepted: the “sliding filaments” theory. Even if this hypothesis was able to justifysome form of muscle contraction, other processes are not fully described by it. Eccentric contraction andsome phenomena, like the “force enhancement during stretch” concept described in the 2002, are notexplicable according to the sliding filament theory. Therefore, several hypotheses have been suggested overthe years, such as the “popping sarcomeres” theory and the “winding filament” theory. Some other proteins,like titin, have gained a main role in the physiology of the sarcomere and should be relevant to explainmechanisms of eccentric contraction, where the sarcomere generates highest level of tension while it islengthening. The aim of this review is to summarize the physiological theories of muscle contraction and todefine concepts applicable in sport medicine and in rehabilitation areas.