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Monday, March 30, 2015

Cycling While Fasted

Conventional wisdom: fuel, fuel, fuel, or horrible things will happen to you!  You'll bonk, you won't get the best out of your workouts, and things will just generally go off the rails.

No Fuel?

I have been reading a bit more about endurance athletes working out in a fasted state.  This article provides a pretty good summary, including some of the actual scientific studies that have been done.

The studies have generally been small, but suggest there may be something to this.  So I tried it.

Every impulse I have is that this is wrong... years of gulping down sports drinks have made me feel like I rely on getting those energy hits.

The Test

A two hour ride, with lemon juice + table salt mixture (pottassium+sodium) and a few Nuun tablets (only 10 calories each, so close enough to fasted for the purposes here).

Oh, and I was at the end of my 16 hour "fast" window... by the time the workout was done I had fasted for 17 hours.


Shockingly it went great.  Really, really great.  I had energy the entire ride, no sense of fatigue (other than what I would normally feel).   I honestly expected my energy output to be too high for my body to produce from just what was already in me (fat, glycogen) - and thought I would bail on the ride at some point to find some sugar, oh sweet wonderful sugar... but nope, got to the end no problem.

The Strava Data:


I certainly can't conclude this is a better or worse way to train, as I have no idea what the adaptations from this will be.  All I know is I felt good.  The studies suggest this kind of training increases your ability to store glycogen, significantly - so if true, then fasted training should lead to me having more energy in a race.

What I can conclude is that a lot of what I've come to know has been wrong.  I've relied on energy drinks, but that could be as much of a mental crutch as a physical need.

It will be interesting to try this in the summer for a truly long ride.  Until then I will make a weekly fasted ride/run part of my schedule, and we'll see!

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