Tryptophan floats around in the blood, it crossed the blood-brain barrier and is a precursor to seratonin. Seratonin affects mood, particularly lathargy and is linked to a central fatigue hypothesis, possibly also affecting cognitive processes important in orienteering (not just feeling tired).
As the bodies CHO stores are lowered, the ratio of tryptophan to certain amino-acids increases. The amino-acids (specifically branch-chain aminon acids) compete for transportation across the blood-brain barrier and in fact have a higher affinity for transportation.
I like that idea. Makes sense. But if this is the case then could runners just take Prozac to ward off fatigue. Easily tested ...
Eat enough meat (that doesn't means heaps)
Jo Fenn, 800m athlete, has put down her recent increase in performance to giving up vegetarianism at the start of 2003.
chinese hamster ovary?
Carbohydrates is the CHO in question, but who knows, chinese hamster ovaries may work equally well. Although they are a little less readily available.