The 30k wall during the marathon - Copacabana Runners

During long distance races, like the marathon, it is usual to see athletes running most part of the course with satisfaction, joy, enthusiasm and even waving to the fans along the race. It seems these runners don't feel the heat, their strides are strong, their pace steady, but, with no clear reason, their arms become heavy and the legs move with difficulty; the muscles contract with pain, the pace slows down abruptly and each step become an endless torture.

This circumstance, which happens with frequency among long distance runners, is a physiological drawback known as "the 30k wall".

"Wall" is an appropriate word to describe this situation, since it seems to the runners they hit an almost impossible-to-overcome wall.

What determines the appearing of this "wall" is: the effort duration (too much time running), the effort intensity (too fast pace) and the climate conditions. So this "wall" shows up when there is lack of blood stream glucose, lack of muscle glycogen or body overheat.

In the first case, the runners hit the "wall" after 2-3 hours of running when the bloodstream glucose has been consumed by the muscles to produce energy. It provokes hypoglycemia (low level of blood stream glucose), so the body lacks fuel and the athlete have to slow down or quit the race.

Slow runners are the most affected by hypoglycemia because they don't have a good fitness level that allows then great performances during long distance races. So, they take hours to finish the race and, the more time they spend running, the more troubles they have to face. They can even go far, but they will suffer heavily the lack of blood stream glucose.

Nonetheless, hypoglycemia can be avoided as long as the runner starts the race with a high hepatic glycogen levels. The liver stores glycogen that, when it is necessary, can be converted in glucose to maintain the blood stream glucose levels. So, with the appropriate carbohydrate ingestion before and during the race, the athlete can run in a comfortable pace and get good performances at long distance races.

The second cause of the "wall" is the most frustrating one. It affects fast runners and attacks with no warning signals. The fast runners, due to the their strong pace, use their muscle glycogen stores as fuel which can be depleted too soon.

There is nothing you can do when glycogen stores are empty in the exercising muscles. The pace slows down very fast and the athlete, that was running very well, must give up the competition and watch, with no reaction, his opponents surpassing him. However, the lack of muscle glycogen can be prevented by well-oriented training and a diet that supplies the correct daily amount of carbohydrates (at least 60-65% of the total calories intake). Unfortunately during the race there isn't too much to be done.

The third cause of the "wall", body overheating, is the most dangerous. It can even put the athlete's life in danger. So, racing under unfair climate conditions when the temperature and humidity are too high for an athletic event, can disturb the athlete's heat regulation system leading to serious body damage and even causing death.

In order to avoid overheating, runners should drink with regularity during and after training and competitions following the specialist's recommendations.

We can overcame with success this physiological drawback by understanding the causes of the "wall" and how to avoid it with well oriented training, balanced diet and appropriated ingestion of drinks and carbohydrates during the race.

This article has informational purpose and isn't a substitute for professional advice.

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