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Overtraining following intensified training with normal muscle glycogen
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1995
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The study aimed to test whether adequate carbohydrate intake during intensified training prevents athletes from becoming over‑trained. Eight male competitive cyclists underwent three training phases—normal, high‑intensity overtraining, and recovery—while receiving 160 g of liquid carbohydrate within two hours post‑exercise, and overtraining was assessed using five criteria including workload, heart rate, lactate‑RPE ratio, cortisol, and questionnaire responses. Despite similar dietary intake, carbohydrate percentages, and resting muscle glycogen across periods, all participants met at least three overtraining criteria, indicating that short‑term overtraining can occur even when muscle glycogen is preserved.
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 over-trained. 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 μmol.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.