Achten, J., Halson, S., Moseley, L., Rayson, M. P., Casey, A., & Jeukendrup, A. E. (2003). Effect of diet on symptoms of overreaching in runners during a period of intensified training. Medicine and Science in Sports and Exercise, 35(5), Supplement abstract 1163.

The effects of a high carbohydrate (HCHO) and normal carbohydrate diets during a period of intensified training were compared for symptoms of overreaching. Trained male runners (N = 7) experienced seven days of intensified training after four days of normal training. On three days Ss performed steady state treadmill running for 60 minutes followed by a self-paced 8-km all-out run. On four days Ss ran 16-km all-out. During the two conditions they consumed a high or normal CHO diet.

Time to complete the 8-km run was significantly increased by 61 seconds in the HCHO condition and 155 seconds in the normal condition. The 16-km times were only increased in the normal CHO condition. POMS mood scores increased more in the normal condition. During exercise at 58% VO2max carbohydrate oxidation decreased significantly in the normal carbohydrate condition while there were no changes in the HCHO condition. On day 11, muscle glycogen during exercise was significantly higher in the HCHO condition than the normal condition.

The decrease in CHO oxidation during seven days of normal CHO diet was completely accounted for by a decrease in muscle glycogen oxidation. A HCHO diet stalls the occurrence of overreaching symptoms when compared to a normal diet but does not prevent it.

Implication. In comparison to a normal CHO diet, a high CHO diet allows a greater amount of intensified training sessions to be completed before overreaching occurs

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