Choose the Right Clothing
Choose running clothing that wicks away sweat, not cotton fabrics that can become heavy and soaked with sweat and lead to inefficient cooling and chafing. Pick lighter-colored fabrics. Darker colors absorb the heat, while lighter ones help to reflect it. Even a light-colored cycling helmet can help keep you cooler. A light-colored running hat is also a great choice, as you benefit from its reflective properties. If you're still hot, fill you hat with ice from an aid stations.
Cultivate a Positive Mindset
Don't dwell on elements that are out of your control. The weather conditions are the same for everyone and you need to feel confident in your preparation to handle whatever the day throws at you.
Training and racing in hot and humid conditions can affect performance and possibly lead to severe heat illness. Be smart about exercising and competing in the heat.
Acclimatize for the expected conditions, choose events that are in cooler climates (when possible), train early in the day or indoors, hydrate well, and know the signs of heat illness. Remember that an athlete's response to heat is individualized and you must make adjustments based on your needs, experiences and goals.
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