Studies carried out during the past 45 years on the effects of chronic low-frequency stimulation on skeletal muscle have revealed a multiplicity of adaptive changes of muscle fibres in response to increased activity. As reflected by induced changes in the metabolic properties, protein profiles of the contractile machinery and elements of the Ca2+-regulatory system, all essential components of the muscle fibre undergo pronounced changes in their properties that ultimately lead to their reversible transformation from fast-to-slow phenotype. The chronic low-frequency stimulation experiment thus allows exploring many aspects of the plasticity of mammalian skeletal muscle. Moreover it offers the possibility of elucidating molecular mechanisms that remodel phenotypic properties of a differentiated post-mitotic cell during adaptation to altered functional demands. The understanding of the adaptive potential of muscle can be taken advantage of for repairing muscle damage in various muscle diseases. In addition it can be used to prevent muscle wasting during inactivity and aging. Indeed, pioneering studies are still the sound grounds for the many current applications of Functional Electrical Stimulation and for the related research activities that are still proposed and funded.
Ca2+ regulatory proteins; Electrical stimulation; Energy metabolism; Muscle fiber transformation; Myofibrillar proteins