"Hitting the wall" is a term that athletes use to describe the condition where they physically run out of steam. This generally happens when a person uses up most of the nutritional reserves stored in the body. After hitting the wall, athletes may feel extreme fatigue and an inability to move—they may even experience some mental effects. If a person tries to persist in exercising after hitting the wall, he may pass out from exhaustion.
To avoid hitting the wall, most athletes will try to increase their carbohydrate intake prior to any exertion. When people are performing any kind of exercise, the body will generally burn either fat or carbohydrates. A person's body burns fat more slowly and efficiently, but it is harder for the body to access fat. Carbohydrates are burned more quickly, but they also run out quickly.
During an athletic performance, athletes are usually pushing themselves pretty hard. They may initially rely more on carbohydrates during the early portions of an event. Once a person uses up their carbohydrate stores, the body will generally switch to exclusively burning fat, and then at some point, the individual may hit the proverbial wall if they push things too far.
One of the main effects of hitting the wall is emotional. People may lose their sense of drive and suddenly feel depressed. They may also suffer from a general sense of confusion, and they may have trouble thinking clearly about what they are trying to do. Some experts think that these mental effects are caused by an overabundance of serotonin in the brain, which seems to be a common effect of running out of carbohydrate energy.
Another contributing factor that may cause people to hit the wall could be insufficient hydration. The body generally needs water to perform most activities, and any kind of endurance-based sport will often cause as lot of sweating, especially if the temperature is high. Sometimes athletes may not hydrate themselves sufficiently before undertaking an activity, and as a result, they might hit the wall faster than they normally would.
In some studies, women have shown more aptitude for endurance-based sporting events than men. Certain experts think this might be because their bodies are more tuned to burn fat during exertion. This would generally lead to a higher level of energy-burning efficiency, although men could potentially offset the difference by altering their dietary approach.