What to Know About Sports Nutrition When It’s Hot

Summer is heating up, and I for one, am thrilled. The frigid winter in Salt Lake was excruciatingly long this year. However, hot weather comes with its own challenges especially when it comes to training outside. Physiological stress on the body is high while adjusting to the new, hot temperatures. So, here are a few tips to consider as we move into the full summer heat wave.

Burning Through Fuel

The increased metabolism and muscle contraction required for exercise results in increased heat production. Generally, athletes can dissipate heat through sweat production. In hot weather, core temperature rises because heat production accumulates faster than heat can be dissipated through the skin. Higher core temperatures mean higher physiological strain, and higher strain (read: intensity) results in increased reliance on carbohydrate for energy. Athletes often end up burning through their muscle glycogen stores more quickly in hot weather.

The fueling challenges don’t end there. Gastrointestinal function can also be affected by heat. Blood is diverted away from the GI tract and towards working muscles and skin in an effort to regulate and cool down. Diversion of blood flow away the gut along with increased core temperatures can lead to issues such as delayed gastric emptying, suppressed nutrient digestion, or suppressed nutrient absorption.

When adapting to warm weather, it's important to stay on top of carb intake. Small, evenly distributed intakes of around 45g carb/per hour is a good place to start. Fuel early and often. Because of the increased potential for GI issues, it's best to experiment with simple carbs initially, like sports drinks, gels, or gummies during exercise. If they’re well tolerated, you can experiment with more carb sources.

Staying Hydrated

Higher temps means increased fluid needs. Sweat rate increases in an effort to dissipate heat. Generally, higher sweat losses are a good thing because it means the body is effectively cooling itself off, keeping the core temperature lower for longer. Athletes should increase their fluid intake to account for these losses. Go into workouts well hydrated. Although imperfect, one of the simplest ways to monitor hydration status is to monitor urine color. The goal is to have a pale yellow color. Adequate hydration allows your body to function properly while dehydration can increase the likely hood of GI distress.

Stay on top of your hydration plan. During workouts, sodium based sports drinks tend to increase thirst and therefore increase fluid intake compared to plain water. If possible, keep beverages cold. This also increases palatability and your likelihood to drink. The night before a long ride, fill bottles halfway with water or sports drink, then stick them in the freezer. The next morning fill up the remaining bottle space with cold water. This delays the time for the fluids in the bottle to become hot.

Plan your training routes accordingly. Let’s face it, the most ideal scenario is to carry water with you while running and out riding. Find a hydration system that works for you. As someone who dislikes carrying water while running, I try to minimize the amount I have to carry by planning routes around water fountains and gas station stops. Try to find some shade and out of direct sunlight.

While hydration is important, too much fluid intake can cause its own issues. Exercise-Associated Hyponatremia is a dangerous condition where sodium levels in the blood drop below the normal range. Symptoms can range from mild to severe including lightheadedness, nausea, headache, and in serious cases vomiting, altered mental state, seizure, coma, or even death. The most common cause of exercise-associated hyponatremia is excessive fluid intake so be sure that fluid intake during exercise does not exceed fluid losses.

Post exercise, it’s important to replenish fluids that have been lost through sweat. For every pound of body weight lost, you’ll want to drink 16-24oz. Fluid intake doesn’t have to just come from beverages. Foods like watermelon, cucumber, citrus, tomatoes, lettuces, and strawberries have high water contents and help with hydration.

Keep Core Temperature Down

Summer season is slushie season… and also smoothie season. One of the fastest ways to decrease body temperature is to down an icy beverage. I find smoothies to be especially helpful for athletes in the summer because high core temperatures can diminish hunger cues, and smoothies can provide the necessary carbs, proteins and fluids needed for recovery post training.

Ice is one of the best tools for athletes to use to cool down. Stick some under your hat before heading out the door. Ladies, those sports bras/tops with phone pockets, try filling those pockets with ice. You won’t regret it. During training, keep yourself cool by tipping water over your head and exposed skin. This works especially well in hot dry climates (Hello, Arizona!). In areas with relatively high humidity, pre/post-cooling strategies such as ice vests or post exercise ice bath may provide more benefit. If other options aren’t available, starting and ending training sessions in a well air-conditioned room can diminish rises in core temperature.

For both athletic performance and safety, it’s important to try to minimize the risk of overheating. Whether you love or hate the hot weather, a thoughtful nutrition approach can help you beat the heat.

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