Posted by Dave on July 7, 2011 | 8 Comments
Two separate individuals have pointed me to a new site, The Natural Running Center, which claims to be “a comprehensive web resource of information and education for all runners.” The site was founded by minimalist running gurus (advocates of running barefoot or with very reduced footwear), some of whom also happen to operate stores where you can buy minimalist running gear.
I’m always a little leery of accepting advice from folks who are trying to sell you something other than advice, but I do suspect that the people running the site probably believe in what they are doing. There’s also little doubt that there is some truth in some of the general principles they advocate. That said, so far the site unfortunately doesn’t live up to its promise.
Let’s just consider one example, a post on nutrition and injuries, which claims that diet is “perhaps the most important factor” causing injuries in minimalist runners. The article, written by a chiropractor, makes literally dozens of unsupported claims. I won’t try to debunk every one of them, but instead focus in on this one:
A high-carbohydrate diet, especially refined sugars like high fructose corn syrup, white sugar and flour, and yes, even agave, will contribute to the inflammation and even increase insulin levels over time. Eventually your tissues will become resistant to the insulin and blood-glucose handling problems will result. You may bonk or under-perform in a race because of this, or have mood swings and general body aches due to the carbohydrate sensitivity.
Don’t get me wrong, high-carbohydrate diets have contributed dramatically to the obesity epidemic in the U.S. and elsewhere in the world. But if you’re a runner who trains regularly and is at a healthy weight, does a high-carb diet in and of itself cause you to “bonk or under-perform in a race”? The evidence suggests otherwise. Carbo-loading, while difficult to achieve, does elevate muscle glycogen levels and may lead to improved performance in long races.
As Matt Fitzgerald points out in his book Racing Weight, a high-carbohydrate diet — over 65 percent of total calories — has been shown to improve racing performance in extreme circumstances. While more realistic tests have come up with mixed results, never has a study found that a high-carb diet diminishes performance or leads to bonking compared to other diets. And as Fitzgerald observes, the most-accomplished Kenyan runners as a group tend to consume extremely high proportions of carbohydrates: Over 75 percent of total calories, according to one study. If the best distance runners in the world consume extremely large volumes of carbs, there is little doubt that carbs don’t cause them to bonk.
But most nutritionists agree that highly-processed carbs like corn syrup and white bread are not great diet choices; they would suggest consuming most of your carbs in the form of fruits and vegetables and whole grains.
What does this mean for you? As long as you’re not gaining unwanted weight, there is no evidence that a diet rich in high-quality carbs like fruits and vegetables will impair your performance in races. Indeed, even some “low-quality” carbs like energy gels and drinks are probably fine as long as you’re burning those calories off in workouts.
And, most importantly, when reading nutrition advice, make sure your sources cite scientific data to back up their claims.