OVERTRAINING AND GLYCOGEN DEPLETION HYPOTHESIS

Low muscle glycogen levels due to consecutive days of extensive exerci se have been shown to cause fatigue and thus decrements in performance . Low muscle glycogen levels could also lead to oxidation of the branc hed chain amino acids and central fatigue. Therefore, the questions be come, can low muscle glycogen not only lead to peripheral and central fatigue but also to overtraining, and if so, can overtraining be avoid ed by consuming sufficient quantities of carbohydrates? Research on sw immers has shown that those who were nonresponsive to an increase in t heir training load had low levels of muscle glycogen and consumed insu fficient energy and carbohydrates. However, cyclists who increased the ir training load for 2 wk but also increased carbohydrate intake to ma intain muscle glycogen levels still met the criteria of over-reaching (short-term overtraining) and might have met the criteria for overtrai ning had the subjects been followed for a longer period of time. Thus, some other mechanism than reduced muscle glycogen levels must be resp onsible for the development and occurrence of overtraining.