One thousand calories. Roughly a third of many athletes' normal daily allotment. That's how many calories you're likely to burn during the swim of an Ironman-distance event. With a 5,000-calorie bike ride and a 3,500-calorie run yet to come, that's a pretty deep hole you've dug for yourself, and the event has only just begun.
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There's really no way to avoid burning a ton of calories during the swim—or to prevent an energy deficit by eating in the water—but your performance for the rest of the day depends on adapting your nutrition strategy to compensate for this deficit. Fortunately, a few tweaks to your pre-race routine and your bike-leg nutrition can help you catch up on lost calories from the swim and set yourself up for a strong run.
Keeping Topped Up
Breakfast is the most important meal of the day, and that old adage is never truer than on race day. You burned most of the carbohydrate stores in your liver overnight, and breakfast is your last big chance to pack more carbohydrate into your body. From then on, it's a constant battle between using energy and replacing it.
The body runs on a seemingly flawed system that lets us burn energy faster than it can be replaced; you can easily burn 800 to 1,000 calories per hour, but you can only replace a portion of that. To maximize performance, it's crucial that you start with as much fuel as possible in your body, and that you consume enough calories during the event to maximize the replenishment capacity of the system.
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Plan to get up a few hours before the start of the race so you can eat a large breakfast and give it time to digest. For most people, this means sitting down to your final pre-race meal three to four hours before the start. You obviously don't want to go to the swim start with food sitting in your stomach, so practice your race-day plan in training to know exactly what you'll be eating and how much digestion time you'll need to feel comfortable when you start racing.
Before shorter events, like sprint- and Olympic-distance triathlons, you can often get away with a smaller meal about two hours before the race. And for all race distances, it's a good idea to consume a bottle of carbohydrate-rich sports drink in the last hour before the start.
Before you know it, however, the gun goes off, the swim goes by in a blur and you're out of the water, ready to start hammering on the bike. And no matter what you did before the race, you're in a caloric deficit again. Some experts recommend taking 10 to 15 minutes on the bike to get adjusted before you start eating in order to avoid stomach problems, and if you have a finicky gut, this may well be the best tactic for you.
The problem with this approach, however, is that you're already low on calories, and another 10 to 15 minutes just puts you further behind. Thus, if you are able to handle calories immediately after the swim, you may want to double-up on calories at the beginning of the bike leg and then settle into your normal nutrition strategy. Specifically, instead of waiting for that first 20-minute timer to go off, take in your first bottle of sports drink plus a gel or a bar as soon as possible after exiting the water.
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If you can handle it, downing a bottle of sports drink in the transition area lets you roll out onto the course a step ahead on nutrition and hydration and with two full water bottles on your bike. Similarly, eating a gel or bar in transition or in the first few minutes out on the course will help replenish energy burned during the swim and put you on the right track to keep the tank as full as possible.
Breaking it Down
For most athletes, the bike leg is the easiest time to consume solid food. One good option is to break the food component of your race-day nutrition into more manageable 100- to 150-calorie chunks. That's the equivalent of a gel, half an energy bar or a large banana. Since most athletes find gels to be easier to eat—and easier on the stomach during the run—the bike is a good time to focus on solid food.
This is especially important in daylong events like an Ironman, because increasing the variety of foods in your nutrition strategy means you'll be more likely to keep eating frequently. Along with water, drinking a bottle of sports drink during the course of each hour will add about another 100 calories.
The long-course triathlete's plan boils down to this: Make sure you eat as large a breakfast as you can handle, then try to consume about 150 calories as soon as possible after you exit the water. Following that, settle into a normal feeding schedule of 100 to 150 food calories every 20 minutes. Combined with the sports drink, you'll be consuming about 400 to 550 calories per hour, which is about the maximum most people can handle.
It's not complicated, but inserting that carbohydrate-rich feeding before the bike is critical. It fills an important gap in the nutrition strategies of many athletes by replenishing some of the energy burned during the swim. This will lessen the caloric deficit most of your competition will be struggling with.
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