Overtraining following intensified training with normal muscle glycogen

The purpose of this study was to determine if consumption of appropriate amounts of carbohydrate during a period of increased exercise training would protect the athletes from becoming overtrained. Eight male competitive cyclists were monitored and tested during three training periods: a) normal training (moderate intensity, long duration, 7 d, NORM); b) overtraining (high intensity training, 15 d, OVER); and c) recovery (minimal training, 6 d, REC). Throughout the training 160 g of liquid carbohydrate were consumed within the first 2 h after the daily exercise bout. Mean dietary intake (NORM = 13.7 +/- 1.6, OVER = 14.1 +/- 1.0 MJ.d-1) and carbohydrate percent (NORM = 64.0 +/- 2.1, OVER = 67.4 +/- 2.5%) were not different during the different training periods. Similarly, resting muscle glycogen levels were not different (NORM = 530.9 +/- 42.5, OVER = 571.2 +/- 27.5 mumol.g-1 dry weight). Five criteria were used to determine if overtraining occurred in a subject (decreased maximal workload, maximal heart rate, ratio of maximal lactate to rating of perceived exertion (HLa:RPE), and resting plasma cortisol levels, increased affirmative response to a daily questionnaire). All subjects met at least three of the five criteria and thus were classified as overtrained. Therefore, short-term overtraining may occur even when resting muscle glycogen levels are maintained.