Staying Cool in Summer’s Heat and Humidity: Tips for Runners or Anyone Exercising Outdoors

Before the rainy season got underway in South Florida, the area saw record high temperatures. And a heat wave persists across much of the U.S. Even experienced runners or cyclists accustomed to sweltering heat and humidity have found it more challenging to stay cool and hydrated.

The overwhelming heat is a factor for everyone to consider if exercising outdoors this summer and fall, explains Alex Mafdali, M.D., a primary care sports medicine physician with Baptist Health Orthopedic Care.

“It is extremely important for even experienced runners and others who workout outdoors to take extra precautions when it comes to hydration and avoiding the peak times of the day,” said Dr. Mafdali. “Preparation is key , consider the timing of your workouts. I would advise against exercising during the peak hours of the hot summer day, and prefer exercising either in the morning or in the evening when the temperatures are cooler.”

Alex Mafdali, M.D., a primary care sports medicine physician with Baptist Health Orthopedic Care..

What’s the best time of day for exercising outdoors? Early morning or evenings usually offer the best time-frames. The key is to avoid the sun’s harmful UV (ultraviolet) radiation at the peak of the day, roughly 10 a.m. to 4 p.m.

“Besides cooler temperatures, exercising in the morning may provide better air quality, and can help establish a consistent routine where there are fewer distractions/commitments in addition to increasing metabolism and energy,” explains Dr. Mafdali. “Exercising in the evening also provides cooler temperatures. And it may be an opportunity to destress, allowing for greater flexibility. And can be more social. Plan your route and try to incorporate shaded areas. It is imperative to drink plenty of water before, during and after exercise. Take frequent breaks if needed.”

Many runners head outdoors during their lunchtime break close to noontime, which is peak time for UV radiation.

“I would recommend them finding an alternative time to run to avoid the excessive heat,” said Dr. Mafdali. “However, if this is the only time they are able to exercise, then there are couple of things I would recommend. Make sure to stay hydrated and dress appropriately. Wearing light-weight and light-colored, moisture-wicking clothing -- possibly even a hat and sunglasses. Do not forget about sunscreen.”

Here's more vital advice from Dr. Mafdali:

What are the top 3 tips you would give to someone who is considering or starting to exercise outdoors in this heat and humidity?
Dr. Mafdali: “Hydration, hydration, hydration. Listen to your body and know your limitations. Make sure to take the time to acclimate, with a gradual increase in the intensity and duration of your workouts over a week or two to allow your body to adapt. Time your workouts wisely.”

 Are sports drinks better than water to replace the sodium, chloride and potassium you lose through sweating in this intense heat and humidity?
Dr. Mafdali: “Both sports drinks and water play a pivotal role in hydration strategies for outdoor exercise in the heat and humidity. Sports drinks are particularly beneficial for longer, high-intensity workouts in hot conditions due to their electrolyte and carbohydrate content. Whereas for shorter or less intense activities watery is usually sufficient. Ultimately, the choice depends on the duration, intensity of your work out, and personal preference.”

Can you explain why muscle cramping can be a sign of dehydration?
Dr. Mafdali: “The main cause of heat cramps is dehydration and electrolyte imbalance, especially a lack of sodium. When you sweat heavily during exercise or exertion in hot environment, your body loses fluids and electrolytes. This can lead to muscle cramps, most commonly in the legs, abdomen and arms.”

What are the top signs of impending heat illness while exercising outdoors?
Dr. Mafdali: “Heat illness is typically grouped into two categories: Heat exhaustion and heat stroke. Heat exhaustion includes signs of heavy sweating, muscle cramps, weakness, headache or nausea. Heat stroke is a severe form of heat illness, which includes a body temperature above of 104 or higher, decreased sweating, and confusion or unconsciousness that requires immediate medical attention.

“If any of these symptoms occur, it is important to stop exercising, seek shade, hydrate cool down. And if symptoms worsen, seek medical attention. Cold water immersion is essential for those experiencing signs of heat stroke.”