Glycogen loading and endurance performance

It is common for endurance athletes to engage in glycogen loading or carbohydrate loading as it is more commonly called. They believe that this coupled with a modified training programme will maximize glycogen stores and lead to improved performance. Some researchers such as Hawley et al. (1997) as cited in Antonio (2008) suggested that glycogen loading of supercompensation can be beneficial for endurance bouts that last longer than 90 minutes. It is reported by Hawley et al. (1997) that glycogen loading can reduce fatigue during endurance training and increase duration of exercise bout by 20% while increasing workload or distance completed by 2-3%.

Accordingly to Antonio (2008), the classic carbohydrate loading method requires a 3-4 day glycogen-depleting regime which contained hard exercise coupled with a low carbohydrate diet followed by a 3-4 day repletion phase in which training volume and intensity were decreased whereas carbohydrate consumption was significantly increased. The drawback of this method is that workout quality suffered during the depletion phase and optimal performance was not achieved.

Sherman et al. (1981) as cited in Antonio (2008) proposed an alternative method. It required the athlete to consume a 50% carbohydrate diet for 3 days while slowly reducing training volume. The athlete will consume 70% carbohydrate diet from the fourth day while still reducing training volume. On the seventh day, the athlete will compete. The authors reported that this modified method is highly effective for loading glycogen with less risk of performance decrements than the classic method.

References:

Antonio, J., Kalman, D., Stout, J. R., Greenwood, M., Willoughby, D. S., & Haff, G. G. (Eds.). (2008). Carbohydrates. In A. Haff, G.G (Eds.),  Essentials of sports nutrition and supplements (pp. 301). Chapter Humana Press.

Hawley, J. A., Schabort, E. J., Noakes, T. D., & Dennis, S. C. (1997). Carbohydrate-loading and exercise performance. An update. Sports medicine (Auckland, NZ), 24(2), 73.

Sherman, W. M., Costill, D. L., Fink, W. J., & Miller, J. M. (1981). Effect of exercise-diet manipulation on muscle glycogen and its subsequent utilization during performance. International Journal of Sports Medicine, 2(2), 114.