Muscle glycogen provides a key fuel for training and racing a marathon. The term “hitting the wall” is really referring to the overwhelming fatigue that an athlete experiences at a later part of an event when muscle glycogen stores are depleted. Hence, carbohydrate (CHO) loading can enhance endurance/marathon performance by allowing the competitor to run at their optimal pace for a longer period before fatiguing.

Classic VS Modified
- The classic model (Ahlborg, Bergtrom & Brohult, 1967) follows a 7-day process which involves 3 to 4 days of depletion phase of hard training and low CHO intake follow by a 3 to 4 days loading phase.
- This is not practical as it can result in more fatigue and hence over training.
- Modified model only requires simply 3 days of high CHO intake while tapering for your event w/o any prior depletion of glycogen (Sherman, Costill & Fink, 1981).

Guidelines to a successful CHO-loading
- A CHO loading regime will involve 72 hours or CHO intake between 8 to 10g/kg body weight while keeping fat intake low (20 to 30g daily) and protein to 1g/kg body weight.
- Avoid high fiber product such as wholemeal or wholegrain as it is difficult to consume a large quantity of it to meet the demands of the loading.
- Athletes who struggle to meet the loading demands can utilize refined CHO such as soft drinks, jelly, pudding, candy etc. to supplement their intake.
- It is important for the athlete to know that CHO loading is likely to be associated with a weight gain of about 2kg. This needs to be viewed as positive reinforcement that they have significantly increase glycogen stores.

End of text references
- Ahlborg, G., Bergtrom, J., & Brohult. J. (1967). Human muscle glycogen content and capacity for prolonged exercise after different diets. Forsvarsmedicin, 3, 85-99.
- Sherman, W.M., Costill, D.L., & Fink, W.J. (1981). Effects of exercise-diet manipulation on muscle glycogenand its subsequent utilisation during performance.
- International Journal of Sports Medicine, 2,114-118.