Elite Marathoners and Low Carb Training
A while back, I wrote a blog about intermittent fasting and the benefits of teaching the body to burn fat for fuel over carbs. As a runner, this could be important because your body can only hold a limited amount of carbs and once you burn through them, you are more susceptible to fatigue. On the other hand, your body has way more fat than you could ever burn through on a 26.2 mile run. Therefore, if you can teach your body to burn fat for fuel, you potentially have an unlimited fuel source. Personally, I enjoy carbs so I’m pretty sure I could never completely transition to fat over carbs. Nevertheless, I do think there is something to be said for doing a workout in a carb depleted state.
I came across this blog post from Sweat Science that picks apart the details of a recent article in International Journal of Sports Nutrition and Exercise Metabolism. Basically the article outlines many details of three elite marathoners but the part that interested me the most was that they incorporated hard workouts in carb depleted states into their training. Even the elites are trying to teach their bodies to burn fat more efficiently…
Alex Huthinson, Sweat Science:
Another topic the paper gives lots of details on is “low carb training” — in other words, training with “empty” muscles to force your body to adapt by learning to burn fat more efficiently. (As Stellingwerff points out, this is a question of when you take your carbs, not whether. None of the athletes was following a low-carb diet.) There have been lots of articles about the theory of carb-restricted training, but this is a rare glimpse of how elite athletes are actually using it.
During the early and middle phases of their training, the athletes averaged about 2.5 low-carb sessions per week; in the final weeks, they reduced that to 1.3 sessions per week. The vast majority of these sessions simply involved running first thing in the morning after taking only water or coffee. They also did some harder sessions that involved doing a hard interval workout in the morning, restricting carb intake during the middle of the day, then doing another run in the afternoon — but they only did a few of these (11 out of 107 total low-carb sessions) because they were so hard.
Working out on empty is hard. I’ve tried it before. But I’ve read quite a few articles and listened to several interviews from people who swear by the effectiveness of burning fat over carbs. The only thing though that everyone says is that there will be a few weeks of tiredness and low energy levels. But once you get past that, you’re good to go. (Side note: most of these articles and interviews were from people who completely cut carbs out of their diet, unlike the elites mentioned above who just ate carbs at different times throughout the day.)
I’m holding off on my long run until Sunday because my tendon is still a little swollen in my leg. However, tomorrow morning I will be at the gym for some cardio on the bike. Maybe I’ll go in a carb depleted state 🙂
Happy Trails and Happy Running,
Tracie
Run Inspired. 
I’m a big believer in glycogen depletion training and think it is a huge benefit of running before breakfast. I don’t think there has been anything more valuable in my marathon preparations than knocking out 20+ milers with some work at marathon paste consistently on very little fuel. In last fall’s marathon, I suffered no bonk despite not taking in any gels, only Gatorade, on the course.
That’s really interesting to know. Since I posted this yesterday a few people (who all just happen to be really fast like you) have told me that they do low carb training. To be able to run a marathon and not hit that energy low or have to worry about gels, would be really nice. In your opinion, since I run in the afternoon after work (before work just really isn’t possible since I leave for work before 6am), how would I incorporate the low carb training into my diet? Stick to low carbs throughout the day and then eat carbs after my workout? And is there a certain amount of time you would recommend not eating before a run to really be in that carb depleted state?
Most recommend fasting for 8 hours before you run, but that late in the day, I’d suspect eating an early lunch and going without anything for the afternoon should suffice. My approach isn’t so much diet-related (i.e., I don’t go low carbs), but because I run in the morning, it’s easy to consistently go out in a fasted state. This doesn’t need to be something you can do weekly – see if you can do a 90 minute run once/week this way – or your long run on the weekend, which may be easier for you to do in the morning.