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Heat: Secret Weapon? (Part 2)

author : alicefoeller

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Make hot weather your secret weapon by understanding how it affects digestion.

Updated Aug. 31, 2020

Part 2: Eating and Drinking Smart When It's Hot

Part of the reason we feel terrible and have worse race results in very hot weather is because it's difficult for our bodies to handle food and even plain water when in extreme heat. In this article, we explore strategies to eat and drink strategically in hot weather, giving you an edge over the competition.

Beginning with a Disadvantage

Our digestive system is already not having a great day when we are exercising and trying to stuff food and drink in our mouths. Blood flow to the stomach and intestines is required for them to work, and exercise shunts that blood flow to our muscles. So, we're starting with a disadvantage.

Now let's add heat to the equation. Our body is trying to balance sending enough blood to fuel our muscles, and now diverting as much blood as possible to the surface of the skin, where sweat is getting our skin wet so the air can cool it. If it's really hot, the body is sending a lot of blood to the surface to try to cool it. That doesn't leave a lot of blood left to run our digestive system. As a result, the stomach tends to just shut down. We don't feel hungry. Our stomach might recoil at the idea of sports drink or even water. If we did eat something, it may feel like a rock in our stomach ... or worse, come back up.

Different race lengths = different strategies

For a sprint or even an Olympic on a very hot day, it makes sense to listen to your body and not force down unwelcome food or drink. There is enough stored energy in your liver to go for about an hour with easy-to-burn fuel. If you've been training well, your body has learned to burn fat after that, and you really don't need to eat. This will backfire if your maximum training sessions have been only an hour long, and the race is the first time you'll be going longer. If you are racing virtually, you can start earlier in the morning, when it's cool.

Tip 1: Start now by doing longer sessions on the swim and bike (where you won't get injured by going long) just to get your body accustomed to running out of stored sugar and switching to burning fat. That way if you can't stomach a sports drink or gel, you'll still be alright.

For a half-ironman or iron distance race, it's not realistic to race without taking on fuel of some kind during the event. The challenge at these distances is that it's much harder to simulate in training. Even if you swim longer than 2.4 miles in training, or bike longer than 112 miles in training, it's going to be difficult to do a 10+ hour training session without blowing your training plan or your race. That makes it tough to predict what you body needs at, say, 3pm when you've been going since sunrise.

Tip 2: For a longer race, formulate a nutrition plan, and practice it. Even though it won't be exactly like race day, you'll eliminate some variables by training with the type of food you plan to use on the course. If you aren't averse to what they will be serving at aid stations, find out what that will be and train with it. It's less to carry with you and worry about.

Tip 3: Pay special attention to how you feel on training days that are especially hot. Instead of chalking up a bad training day to terrible heat, see what you can learn. Be observant about what you tried and what didn't work. Did you feel OK drinking a sports drink, but you couldn't choke down an energy bar? Keep good records in your training log.

For all distances, you can give yourself an edge by timing your eating and drinking.

Tip 4: You are likely to feel the worst on the run, because it's later in the day when the sun is hotter, because your heart rate is the highest on the run, and because you are jostling your guts around with every step. Fuel as much as you can before the race starts, and in the beginning and middle of the bike portion.

If you are really suffering and you are not trying to win a spot on the podium, consider waiting to down that energy gel or even take the gulp of water when your heart rate is lower. Your heart is already struggling to take oxygen and fuel to the muscles, and to cool your body. Asking it to make your digestive system work, too, can be a tall order. For best results, time your consumptions to moments of lower heart rate.

Tip 5: If you are planning to take a walk break anyway, and you are feeling queasy, don't start drinking as soon as you break your stride to walk. Walk for 10 or 20 seconds and wait for your heart rate to drop a little. Or take on food or fluids during an easy section, such as a long, steady downhill. To help your heart even more, throw some cold water on your skin and head first so your body has help with the cooling process, and then put some water or sports drink in your stomach.

Technology has produced an endless array of new energy gels, bars, tablets, powders and drinks. Study the options against your normal training diet, and make a match. For example, if you don't eat dairy, make sure your race foods are dairy-free also. This will help head off stomach rebellion. It also helps to have established a healthy microbiome in your gut in the first place. If you've had to take a round of antibiotics, or you eat food containing preservatives (which preserve food by being toxic to bacteria) you may need help reestablishing healthy gut bacteria. New research is showing a healthy gut can also improve cardiac function and mood, so it's a no-lose proposition. The most important thing is not to surprise your body. If you do, it's likely to surprise you back, and not in a way that will help you reach your goal performance.

Tip 6: Train the way you race. Don't save a special food or sports drink for race day. Make your race day nutrition your regular "house brand" training food and drink. Pay attention, and if something doesn't agree with you in training, replace it with something that does before your race.