Fueling for the long haul

Hey Athletes

I get a lot of questions about eating during races. Hopefully there is some useful info here for you. If you haven’t practiced your eating, get at’er!!

This was originally written specifically for 1/2 IM distance, but it can apply in general to any activity long enough to require intake of calories.  For most of us, that is 1.5-2 hours and more.  If you feel you need to eat earlier than that, it’s not a physiologic need but a psychological one.  (Unless you started the workout or race tired and bonky)

Half IM race day eating

Half IM for most of us normal humans is a 5-hours-or-more project. Most people will burn through 3500 or more calories (depends on your size of course, and the conditions).

The first thing to remember is you don’t need to eat 3500 calories. Through your extensive endurance training (right!?) your body has become a fat-burning machine. There are about 3500 calories in one pound of fat. Even if you’re very lean (under 10% fat), that still means you have enough fat to keep you going through a number of half ironman races.

The reason you need to eat at all is that at higher speeds, fat only supplies part of the energy you burn. Your body is like a hybrid car. A hybrid has electric power and gas power. At low speed it can run on electric only, but at higher power it has to turn on the gas motor as well. Your body has 2 main energy systems to supply the muscles. At low speeds you burn mainly fat.  As you speed up, you burn carbohydrate and the faster you go, the higher the proportion of carbohydrate to fat that you burn as you fuel mix..

Carbohydrate you burn during a race is mainly stored in your liver and muscles in the form of glycogen, but can also come directly from your bloodstream by what you ate recently and are digesting, or what you eat during the race. Running out of carbohydrate can result in that “bonk” feeling, that slows you down to a walk (at that slow pace the fat-burning system has no problem supplying your energy needs).

As an interesting aside, there is also another significant reason that consuming sugars (carbs) helps during a race. Your body largely slows down because your brain tells it to (probably an evolutionary protective mechanism). When you eat sugars, your brain tells the muscles to give’r, probably sensing that there are enough calories on the way to keep you going. (In some studies swishing gatorade around in your mouth and spitting it out helped as much as actually drinking it)

Just how much carb “fuel” you’ll need during a race depends on a lot of things. Your weight (bigger people need more). Your pace (in general, faster people will burn more carbs as a percent of fuel). Your genetics (some people can do fine with hardly any intake, others bonk easily). Your endurance training level (better training = better fat burning). Your stomach training (see below).

You can train your stomach. The normal physiologic response to exercise is that your body dilates blood vessels in your muscles, and shrinks the blood vessels to your stomach and bowel and “shuts them down”. That’s why you feel so gross if you eat a big meal just before Tuesday Track. But you can train your stomach and gut to turn back on somewhat during exercise by eating regularly during training. In general, most people find it easier to eat on the bike than during the run, something about the jostling and the upright position, and probably the higher heart rate that most people have when running.

So my recommendation is to experiment lots in training. See what you can handle on the bike. See what you can handle on the run. Purposely try some training on a full stomach. Get a sense of what’ll work for you and what won’t.

The only time I eat disgusting artificial things like gels and gatorade is during a race. In training I prefer nuts, raisins, fruit (dried and fresh) and good-for-you things like that. But the pre-packaged products are awfully handy while racing.

The last issue I’ll mention is salt. While many companies try to sell their product by talking about potassium, calcium, and other elements, the really important thing during racing is sodium. Too much water is actually a much more common problem than dehydration. Too much water and too little salt dilutes your blood sodium, resulting in cramps, dizziness, weakness, nausea, and even confusion or passing out. Drink to thirst, don’t force it down, and make sure to drink fluids that contain salt, or eat foods that contain salt. Again, everyone is different in how much salt they lose through sweating, so you’ll need to experiment. If the day is really hot, and you are a salty sweater, it’s actually hard to keep up on sodium by gatorade and gels alone, and you may need to think about salt tablets or foods like pretzels or crackers.

I could go on a lot more, but this is a start. I’m happy to answer any questions or talk to you individually about this sometime.

Be careful about listening to people with one-size-fits-all advice about X-number-of-gels-per-hour, or a prescribed fluid intake per hour. It’s just not that simple, and trying to follow a nutrition plan that works for someone else can lead to serious trouble for you as an individual. The right nutrition plan is the one that works for you – don’t slavishly try to follow a generically prescribed plan.

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