The Overlooked Role of Nutrition in Training Induced Fatigue

Missed my morning FaceBook post due to a 90+ mile bike ride, but it served as motivation for what to write about today.

One of the amino acids which even the most nutritionally ignorant among us has heard of is tryptophan. After all, that's what makes you sleepy after that turkey dinner on Thanksgiving, right? Well, not exactly. But that's not my point.

Tryptophan is the precursor for the neurotransmitter 5-hydroxytryptamine (5-HT), which is involved in fatigue. It's also one of the primary amino acids released when muscle is catabolized during times when fuel is inadequate to meet the demands placed on an organism's physiology. In the case of my group ride this morning, there were many examples of people getting tired. Some of those cyclists could blame their training, of course. Others, however, need to consider how their fueling strategy--both on AND off the bike--might be contributing to their fatigue at a given intensity/duration. When glucose levels/glycogen stores are not sufficient to keep muscle (along with free fatty acids, primarily in the form of PUFAs) from being catabolized to fuel the activity, performance of the activity will suffer or stop altogether.

And if you think about it, it's simply another ingenious example of the body trying to survive. The body believes that fuel is scarce. It has no idea you could simply stop at the next convenience store and buy a coke or, better yet, some o.j. But since you won't stop, you body stops you. Or slows you down--anything it can do to spare the body's limited resources. And it has a lot of built in safeguards at play in these conditions just in case. From the production of serotonin (not the happy hormone you've been led to believe) to the inhibition of glucose utilization via the Randle Cycle, the body's gonna win this one. So you can live to ride another day.

And this time, maybe you'll fuel yourself appropriately.

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