Racing is hard, but racing in the heat adds another challenge. There are a few ways we can mitigate race-day heat stress, including specific cooling strategies and dialing in our hydration and fueling for the conditions.
Cooling strategies
Cooling strategies can help us tolerate the conditions sometimes, even if it simply reduces our perception of heat and/or temporarily relieves some of the physiological strain induced by the heat. Unfortunately, the key word here is temporarily; some of these cooling strategies generally offer very limited benefits in the context of a long event.
Cooling garments
This category includes ice socks, cooling neck towels, and ice placed in sports bras or jerseys. These can typically be applied at aid stations and at store stops on self-supported rides.
Sprinkler or cold water spray
Sprinklers are quick but unreliable, but water an also be poured over the head at an aid station, or we can grab an extra bottle of cold water to drip over our heads as we ride. However, this strategy is less effective in very humid conditions.
Ice slurry/Cold fluid ingestion
These can be used in hot, humid, and still environments but are not as effective in warm, dry, and windy environments, as they may reduce sweating efficiency.
Menthol
Menthol induces sensations of freshness, coolness, and nasal patency via cold receptors present on the tongue and mucous membranes. Menthol mouth rinsing can provide cooling effects, and topical menthol creams/gels/sprays might also help our sensations.
Clothing
Unzipping and/or choosing clothing that allows for air flow across the skin, sweat evaporation, and sunlight reflection helps promote heat dissipation.
Hydration strategies
During hard exercise, one of the most important ways our bodies dissipate extra heat is through sweating. Our individual sweat rate will increase in warmer and more humid conditions, when the intensity is high like at race pace, and when we are heat acclimatized. When we sweat, we are mostly losing the fluid portion of our plasma volume, which can lead to hypohydration or dehydration and related issues if we don't replace enough fluids through drinking. In long events in warm conditions, moderate to severe dehydration is a risk if we don't have a fluid replacement strategy in place.
The warmer or more humid the ride and the more intense, the more fluids we'll want to drink, as our sweat rate will be higher. For example, if your normal rate of drinking is ~500 ml per hour, you could increase that to ~700 ml per hour. Of course, it's a good idea to have planned targets, but don't forget to pay attention to thirst, also.
Rather than drinking plain water, we should use something with added sodium that is palatable and encourages drinking. If it's a sports drink that offers carbohydrates, as well, that's a bonus! My go-to sports drinks for during-ride hydration are Fluid Performance and Skratch Hydration. For reference, a serving of Skratch hydration mix contains 800 mg sodium/L, and a 16-ounce serving of Fluid Performance contains ~500 mg/L. I recommend choosing a product that suits your taste preference and does not cause GI issues at your race intensity in the heat. If you are combining gels and chews with your sports drink, make sure you account for the sodium content in those products, as well. Pay attention to your thirst and taste for salt. Our brains have mechanisms in place to regulate hydration status and sodium concentration, so if you're thirsty for plain water or craving salty foods, listen to those signals.
Keep in mind that our sweat sodium concentration is often highest when we are not heat acclimated. After some time acclimatizing to the heat, our bodies will learn to preserve sodium so that we aren't losing as much per liter of sweat, though our sweat rate will remain high to accommodate the body's need for cooling. When in doubt, listen to what your body is craving. Sometimes we will want more salty fluids, and sometimes we'll want less flavor or more water.
Higher-sodium drinks like Fluid Tactical Oral Rehydration Solution with 1700 mg of sodium per liter can be used for pre-hydrating the night before the race and/or a few hours before the race. They can also be used for rapid rehydration after the race.
Heat, hypohydration, and dehydration can also increase the likelihood of GI distress during racing, so I highly recommend spending a few weeks training your gut to handle higher rates of carbohydrate and fluid intake at race intensity in the heat. For example, if your goal is to race with 90 grams of carbohydrate per hour, make sure you can tolerate at least 90-100 grams of carbohydrate per hour during your pre-event race simulation sessions.
At BaseCamp, we believe that every cyclist has the potential to achieve greatness, no matter where they start. Our mission is to create a community-driven training environment where cyclists and triathletes of all levels can train together, support each other, and grow stronger, faster, and more confident in their abilities. Our cycling training programs are expert driven and tailored to your needs. Whether you're a seasoned pro or just getting started, BaseCamp is where you belong.
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