The Wall

"Hitting the Wall" is a running experience that typically happens around mile 20 and has been described by Dick Beardslee as "It felt like an elephant had jumped out of a tree onto my shoulders and was making me carry it the rest of the way in."

Hitting the Wall is about running out of energy. Usually when we think of this we think of muscle fatigue, but what about brain fatigue? Recent research on the relationship in central nervous system changes and exercise-related fatigue shows that there are neurochemical changes. These changes are likely to be involved in a runner hitting the Wall during a marathon.

During prolonged exercise, the brain's production of serotonin increases steadily and at least in animal studies peaked when an animal collapsed from exhaustion. Elevated serotonin levels cause feelings of tiredness, sleepiness, and lethary. This increase in serotonin is caused by increased delivery of tryptophan to the brain. Research has also shown that Dopamine which causes feelings of excitement, reward, motivation, and pleasure begins to drop as the levels of serotonin rise.

Nutritional approaches to preventing serotonin levels from rising and dopamine levels to fall are being investigated. At this point there is no sports drink or supplement to target these neurotransmitter levels, but one well known fatigue stopper is caffeine. Caffeine may delay fatigue by increasing dopamine levels in the brain. You might not want to down a triple espresso before your run however. ;)