Impact of manipulations of myogenesis in utero on the performance of adult skeletal muscle.

The possibility that early fetal programming affects health or disease status in adult life has been considered in relation to tissues such as the cardiovascular system but not with respect to skeletal muscle. Since muscle mass and function are important for life, it is pertinent to ask whether events during the development of muscle in utero can affect the performance of the tissue in later life. This review discusses the factors that influence muscle performance, outlines the current understanding of myogenesis and examines how manipulations alter myogenic outcome after birth. The performance of muscle is determined by the number, type and size of the muscle fibres, these in turn being affected by a number of factors, and the evidence indicates that the proportions of types of muscle fibre have a heritable component. The formation of muscle occurs early in embryogenesis and it appears that the major impacts on myogenesis are associated with extremes of treatment or embryo manipulations. The impact of extremes of treatment or embryo manipulations on myogenesis is seen in the secondary fibres whereas primary fibres appear to be insensitive or protected. Overall, the opportunities for manipulation of myogenesis in utero to improve adult performance are limited.