High-Carb Diet May Increase Training Load Tolerance

Exercise scientists use the body’s testosterone-cortisol ratio (T:C) as one marker of overreaching and overtraining. Testosterone is an “anabolic” hormone, and testosterone levels tend to be higher when the body is being built up. Cortisol is a “catabolic” hormone, and cortisol levels tend to be higher when the body is being broken down. Thus, a low T:C ratio is associated with classic symptoms of overtraining, including performance decline. Carbohydrate intake influences the T:C ratio in athletes, mostly indirectly, by providing fuel for training and recovery. When carbohydrate intake is inadequate for any given training load, the T:C ratio is likely to decrease.

This was shown in a new study by researchers at the University of North Carolina. Twenty male subjects were subjected to three consecutive days of unaccustomedly challenging endurance exercise. Twelve of the 20 were placed on a 60 percent carbohydrate diet during this crash training camp, while the other eight were placed on a 30 percent carbohydrate diet. The authors of the study, which was published in the European Journal of Applied Physiology, found that the T:C ratio did not change over the three days of heavy training in the high-carbohydrate group but declined significantly in the low-carbohydrate group.

This is evidence that, to a point, the more carbohydrate you consume, the more training your body can handle.