MECHANISM OF OVERREACHING AND REGENERATION-FROM MUSCLE TO THE BRAIN

Abstract

535 Training of athletes consists of repetetive phases of normal training, overreaching and regeneration, and, on the long term, performance should increase. Overreaching is defined as short-time overtraining which can be compensated by adequate regeneration and is associated with typical cellular, e.g. molecular, biochemical and regulatory findings which are discussed in this symposium. A myopathy is observed in skeletal muscle with depressed turnover of contractile proteins, e.g. in fast type glycolytic fibers with an concommitant increase in slow type myosines. Heat shock proteins are increased in overreaching possibly as molecular chaperones. Neuromuscular and alpha-motomeuron excitability are depressed. There is a mild form of a sympathetic nervous system insufficiency with decreased β-adrenoreceptor density and depressed intrinsic sympathetic activity. Adrenocortical response to ACTH is depressed and there is a mild hypothalamic depression of the ACTH and growth hormone response. The contribution of higher brain centers to these regulatory changes and concomitant psychological responses were also demonstrated. Understanding the mechanisms of overreaching will help to enhance the efficiency of training, will help to avoid overtraining and longterm staleness of athletes. Furthermore, the symposium will address possibilities of new therapeutic approaches to the problem of stale athletes.