The New Rules of Marathon Nutrition

Use these six cutting-edge tips to avoid the dreaded wall the next time you tackle 26.2.

When Meb Keflezighi and Ryan Hall reached the 23-mile mark of the 2012 U.S. Olympic Trials Marathon as co-leaders of the race, they were on pace to finish in 2:08:34. Keflezighi wound up stopping the clock at 2:09:08, Hall in 2:09:30. In other words, both runners hit a wall — not catastrophically, but enough to have felt it.

The third man to reach the 23-mile mark, Abdi Abdirahman, also slowed down over the last 3.2 miles of the race, as did the fourth- and fifth-place finishers. In fact, you have to go all the way back to 12th place to find a runner — Ricky Flynn — who held pace over the final 5K of the Olympic Trials marathon.

Yes, pro runners hit that imaginary but very real physiological wall, too, but it’s not nearly the problem that it is for the rest of us. Roughly three out of every four participants in any given marathon cover the second half of the race at least two minutes slower than the first. Many runners slow down even more dramatically after the 20-mile mark, where the wall traditionally hovers. By contrast, less than one in 10 half-marathon participants slow down by a comparable amount, and in races shorter than 13.1 miles hitting the wall is a rare occurrence.

The most common cause of hitting the wall is muscle glycogen depletion. Glycogen, a fuel derived from dietary carbohydrates, is stored in relatively small amounts in the muscles and liver, where it waits to be delivered to muscles via the bloodstream in the form of glucose. Most runners have enough glycogen in their bodies to run 13.1 miles at a good pace. But the marathon is fundamentally a metabolic challenge. If you run the first half of the race even one percent too fast, you risk depleting your glycogen levels. Finishing a marathon without hitting the wall requires storing and conserving enough glycogen fuel to avoid running out of it somewhere between 20 and 26 miles — which, as the statistics show, is not easy to do.

Good pacing is paramount. You’ll burn through precious glycogen stores more slowly if you maintain a consistent pace than you will if your pace is erratic, even if it averages out to be the same. Proper training also helps. A good marathon training plan will increase your capacity to store glycogen and improve your running economy and fat-burning capacity, enabling you to burn through stores at a slower rate.

But pacing and training aren’t enough. You must also maintain an appropriate nutrition plan throughout your training process. However, the thinking behind marathon (and half-marathon) training nutrition has shifted in recent years. Follow these six rules to maximize your training and avoid the wall in long-distance races.

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