Tryptophan and Biking

It’s close upon us — the big Christmas dinner, usually featuring turkey with all the trimmings. And we all know what turkey brings to our bloodstream: tryptophan. That’s an amino acid that flows through your blood vessels to the brain, where it’s converted to serotonin, which is blamed for inducing the post-feast drowsiness that results in nap time after dinner.

But maybe you’ve had the experience of finishing a long and/or strenuous bike ride. It might be nothing out of the ordinary given your level of fitness. Still, a little while after the ride, a wave of drowsiness comes over you. You make your way to the bedroom and flop. And you’re out cold for two or three hours.


It turns out that the poor turkey gets a bum rap for our sleepiness after dinner. Tryptophan is found in most proteins, so it’s not the turkey. It’s the amount of protein we ingest.

What does that have to do with feeling tired after a ride? During strenuous exercise, your muscles use branch chain amino acids for fuel. Tryptophan competes with branch chain amino acids to get into the brain, and since you’re burning the BCAA’s, the tryptophan wins. That can produce fatigue during exercise, not after.

That’s why we munch on energy bars and gulp exercise drinks during rides. The muscles use the carbs as fuel, and in turn that cuts down the amount of tryptophan that can make it to the brain.

My ride the other day was a perfect example. I rode 25 miles, a distance I’m used to, although I don’t do it more than twice a week, and I felt pretty good. I carried one water bottle, and it was nearly drained when I pulled up to the house after the ride. But sure enough, while watching TV after my shower, I dozed off. I awoke just long enough to get to bed and zonk out for two hours.

During the ride, my body was using fatty acids — including tryptophan — for fuel. I just drank water, so I wasn’t doing anything to inhibit the tryptophan from getting to the brain. If I had brought an energy bar, I’m certain I would have stayed awake longer.

So if you’re going to do any riding over the Christmas weekend, keep these hints in mind:

  • Don’t fast before you ride. Fasting raises blood-fat levels, and makes it easier for the effects of tryptophan to be felt.
  • Don’t eat fatty foods for 12 hours before your ride. Fatty foods create the necessary condition for tryptophan to move through the bloodstream.
  • Do eat a carbohydrate meal two hours or so before your ride. That will reduce your blood-ft levels.
  • Do drink a sports drink every 10 minutes or so during your ride — and depending on how long you’re out there, take in some carbohydrate foods, too.

Following these steps not only will ward off fatigue during your ride, but keep you from napping — and missing Christmas activities with family or friends — once the ride is done.

Bike Noob will take a short break over Christmas, and we’ll be back next weekend. I wish the blessings of the season on everyone.


  1. chris says

    Thanks! I’ve trawled the net over the last few weeks/months and this is one of the most concise summaries of eating and exercise I’ve found. Merry Christmas to you and yours.

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