Selected Parameters and Mechanisms of Peripheral and Central Fatigue and Regeneration in Overtrained Athletes

Definition, types, symptoms, findings, underlying mechanisms, and frequency of overtraining and overtraining syndrome have been described in an introductory article to the present volume. During the past 10 years, our increasing knowledge in this field has also been discussed in different original and review articles well as presented at the 1996 Memphis Overtraining and Overreaching in Sports Conference and summarized in a book project. Aim of this present overview, which was presented during the 1997 Reisensburg Castle workshop, is an additional up-dating of our knowledge considering mechanisms underlying overtraining-related performance incompetence in affected athletes with respect to further results obtained in this field during the past 2 years. Particular emphasis has been given to the time-course of regeneration subsequent to overtraining as far as it is known at present. From an operational standpoint, the thesis was followed that findings such as impairment of neuromuscular function depressed β-adrenergic receptor density related depressed lipolysis, glycogenolysis, glycolysis, and heart rate response as well as depressed intrinsic sympathetic activity depressed turnover in contractile proteins depressed adrenocortical and pituitary-hypothalamic responsiveness in an advanced stage or iron deficiency can explain performance incompetence in overtrained athletes, whereas appropriate regeneration should be indicated by their normalization.