Sports Nutrition Part 1: Why to Eat

A few athletes have asked me questions in recent weeks about having no energy for workouts, or finding that about ninety minutes into a long run, everything turned south. In all of these cases, under-consuming food was the culprit. It’s an easy mistake to make, especially if you are exercising in part for weight loss! But you need carbohydrate accessible for your metabolism to use during your workouts. Folks sometimes err on the other side, eating too much (this happens often on the bike in a triathlon, when it’s easier to take in calories), and winding up with a bloated, sloshy, or nauseated feeling.

Thinking on nutrition during exercise is constantly changing. Not too long ago, athletes were prohibited from drinking water during a marathon! Now major races must caution runners about the dangers of hyponatremia, a blood sodium imbalance that can result from drinking too much water. Here are some guidelines on what works for me and my athletes; you will need to experiment to find your own best practice.

Each athlete will have a different set of nutritional needs, based on metabolic rate, stomach sensitivity, intensity of exercise, sweat rate, and other factors. Training is the time to try out various approaches to your nutrition before, during, and after exercise. Mistakes are opportunities to learn and adjust your approach. At least once in training, go with much less food and drink than you are used to, so you can feel the effects of running low on sugar. I find that when my thoughts start to turn negative, it’s usually the result of low blood sugar. At Ironman Coeur d’Alene, I noticed that I felt a little dizzy on the bike when I needed to eat. In our discussion of the race, winner Tyler Stewart pointed out that mood in races is often linked to sugar intake.

It’s much better to err on the side of taking in too little food than to take in too much. If you need more sugar, you can always eat; if you have too much, it’s not going to be pretty: it’ll try to get out the same way it came in.

Sport Nutrition ProductsSports nutrition products are designed to supply you with carbohydrate, which spins into the Krebs cycle, to produce energy by burning glycogen, fat, or protein. Other ingredients may be included in the products, including protein, sodium, or caffeine.

There are two forms of carbohydrate: simple and complex. Simple sugars (anything that ends in -ose: sucrose, dextrose, fructose) deliver glucose to the bloodstream very quickly. Complex carbohydrates (in these products, mostly maltodextrin) break down more slowly. Some products, such as Gatorade, contain only simple sugars. (And in Gatorade, it’s usually high fructose corn syrup.) Some products, such as those by Hammer Nutrition, including Heed and Hammer Gel, contain only complex carbohydrates. And some, such as PowerBar’s, contain a mixture of both simple and complex carbohydrates. Each of these will have a different effect on an athlete, so it’s wise to experiment and find one you find palatable and useful.

Carbohydrate is best absorbed in a concentration of 6 to 8 percent. That’s why you shouldn’t wash down a gel with sports drink: it creates a solution more concentrated than your gut can easily handle, so it sits in your stomach, sloshing around and possibly leading to nausea.

Some products also contain protein, which some athletes find useful, especially in longer events. The inclusion of protein will slow down the rate of digestion. If you’d like to experiment with protein, try Accelerade, Accel Gel, and Hammer’s Sustained Energy and Perpetuem.

Many products contain electrolytes such as sodium and potassium to replace what is lost through sweat. Studies are mixed on the benefit of sodium supplementation, either as part of nutrition or in a standalone product (Nuun, Hammer’s Endurolytes). Some athletes believe that sodium helps prevent cramping. Sodium does seem to help with processing of sports drink and even water, because it helps move the fluid out of the gut and into the bloodstream. This is another place where you’ll need to experiment to find what works best for you.

Caffeine is one of the few legal performance-enhancing substances. During training, try using a caffeinated product and see whether you notice a difference. Studies are showing that caffeine improves endurance by changing our interpretation of pain and by increasing mental acuity. We develop a caffeine tolerance, so you could consider tapering your caffeine intake in the week before a race (don’t cut it out cold turkey or you’ll be miserable), so that you receive more of a boost from the caffeine you ingest during the race.

If you are a coffee drinker, you’ll probably want to have a cup of coffee on race morning. In addition to waking you up and giving you the comfort of routine, it also helps you make a pit stop at home before leaving for the race site.

The most recent research I’ve been reading says that dehydration is not nearly the detriment to performance we have thought it was. If you drink to your thirst, you are probably going to be just fine. If you are a very heavy sweater, and thus losing more fluid, you may need to drink more, or remind yourself to drink; if you are a light sweater, you may need less.

In part 2, we’ll discuss just what to eat before, during, and after your workouts and races.

Photo Credit: Bert V. Jensen,

1 Comment
Tom Caawley

October 14, 2009 at 1:53 pm

Sage – very good piece – thank you. I am still trying to figure out what happened to me at Duke 1/2. I finished but didn’t get the time I wanted. I am now thinking it may have been food / drink related and your article makes me believe that I could have taken in too much on the bike – even though I had practiced with that same amount. I think the extra adrenaline of race day combined with my intake didn’t quite work….

Also, liked your opening line where you referenced that “everything went south.” To show you that it is all a matter of perspective, a quick story. I was getting some ice last year the day before Thanksgiving at a small store called “The Trading Post” located out by Allen & Son on old 86. When I went inside to ask for ice, the worker mentioned in a very thick Southern drawl that the ice machine had broken the day before. “Yup,” he said, “that darn thing up and went north on me yesterday.” I didn’t get it at first and asked him what happened. He said, “you know, it broke….it went north.” To this day, the only time I have heard that expression

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