Carbs and overtraining

Author: Frédéric Delavier and Michel Gundill: Chapter from the book "Sports Supplements for Athletes".
2011-10-15

When intensive endurance testing continues day after day, muscles, as studies show, gradually deplete their glycogen stores. This deficiency is accompanied not only by decreased athletic performance but also by a constant feeling of fatigue. In this case, it is necessary to adhere to a diet that is very rich in carbohydrates to minimize the progressive depletion of glycogen.

For example, trained cyclists were subjected to overloads for a week to lose their athletic conditioning (S. Halson, 2004). One group of athletes consumed a diet containing moderate amounts of carbohydrates (6.43 grams per kilogram of body weight), while another group had a diet that was 22% higher in calories due to a higher carbohydrate content (9.4 grams per kilogram). The increase in caloric intake was achieved through the consumption of carbohydrates in liquid form before, during, and immediately after each workout.

During the final test, athletes had to pedal as fast as possible at 74% of their maximum VO2. The overtraining period caused the results in the group consuming moderate carbohydrate intake to decline by 25%. In the second group, following the carbohydrate-rich diet, the decline was only 16%. After an additional 2 weeks of moderate training, results exceeded baseline by 10% thanks to the carbohydrate-rich diet, while they remained 13% below baseline with the moderate carbohydrate intake diet.

Although a high-calorie carbohydrate-rich diet cannot prevent the loss of athletic conditioning during overtraining, it significantly limits its consequences. However, it should be remembered that energy recovery is just one aspect of overall recovery for the body. Beyond the energy aspect, recovery must occur at the level of muscle fibers, joints, tendons, ligaments, the digestive system, as well as the nervous, endocrine, and immune systems. Of course, one should never neglect the energy aspect, even though it is not the foundation of everything. Yet, as studies have shown, it can help an athlete experiencing overloads.

In the long term, overtraining will certainly change the way we typically utilize carbohydrates. During an entire sports season, researchers observed elite cyclists (J. Manetta, 2002). During the rest phase, the champions' ability to use carbohydrates as an energy source decreases. This ability is optimized when athletes are in very good shape at the beginning of the sports season. Then it declines as overtraining sets in and results worsen by the end of the season.