Impact of manipulations of myogenesis in utero on the performance of adultskeletal muscle

The possibility that early fetal programming affects health or disease stat us in adult life has been considered in relation to tissues such as the car diovascular system but not with respect to skeletal muscle. Since muscle ma ss and function are important for life, it is pertinent to ask whether even ts 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 ex amines how manipulations alter myogenic outcome after birth. The performanc e 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 ind icates that the proportions of types of muscle fibre have a heritable compo nent. The formation of muscle occurs early in embryogenesis and it appears that the major impacts on myogenesis are associated with extremes of treatm ent 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 f or manipulation of myogenesis in utero to improve adult performance are lim ited.