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You can always count on a heat wave during a Canadian summer. But lately those heat waves have been hotter and longer, making it more important than ever to stay cool when the temperature spikes. That’s especially true for anyone who’s determined to exercise in the heat.

Warnings about the health risks of physical activity during periods of high heat are well intentioned, but given that summers are getting warmer and heat waves more common, exercisers need to learn how to manage the heat so they can safely train, play and compete on days when people in the rest of the country are sipping cold drinks in the shade.

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The last two Summer Olympics have provided plenty of opportunities for athletes, coaches and organizers to test out some of the latest strategies for keeping participants cool. Tokyo in 2021 and Paris in 2024 both experienced heat waves in excess of 35 C, with the Tokyo Games considered the hottest in history. Organizers of the Paris Games originally planned to reduce their carbon footprint by forgoing air conditioning in venues and the Olympic Village. But when several countries said they would bring in their own air conditioning, 2,500 units were installed in the Olympic Village, proving the importance sports organizations place on keeping their athletes well cooled.

Hot and humid conditions take their toll on exercisers who can’t dissipate enough excess body heat during a workout or competition. The dangerous combination of intense exercise and intense heat causes fatigue, cramping, nausea, dizziness and elevated heart rate, and in rare cases can lead to death. It also diminishes athletic performance. The harder the body works to manage the heat, the less energy is available to sustain high-intensity exercise, which is why athletes and coaches are so invested in staying as cool as possible during periods of high heat and humidity.

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Tennis player Daniil Medvedev took several medical timeouts during his matches at the Tokyo Olympics, stating he feared for his life in the extreme heat. Numerous athletes vomited and fainted, with marathon swimmers, rowers, track and field athletes, golfers, and rugby, football, soccer and beach volleyball players all speaking out about the negative effects heat has on performance. The idea that global warming will eventually lead to the death of a high-performance athlete in a high-profile event is becoming more likely with each successive summer.

It’s not just Olympians who are faced with extreme heat while exercising. People who train or compete during the summer can’t always exercise indoors on days when heat and humidity spike. And while it’s always advisable to exercise outside of peak sunlight hours, wear light-coloured breathable clothing, drink plenty of water, and reduce the intensity and duration of workouts under those conditions, these strategies often fall short during the dog days of summer.

On days when exercising in the heat is unavoidable, cooling the body from the inside out (lowering core body temperature) and outside in (cooling the skin) are two important strategies aimed at reducing the risk of heat-related performance deficits and health issues.

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Cooling from the inside out is done primarily by drinking cold water or a slurry made of crushed ice. Not only do cool liquids effectively lower core body temperature, they reduce the feeling of being overheated, making it easier to exercise.

Lowering skin temperature can be done through techniques including the use of ice packs, wet towels, ice baths, misting and showers.

Adopting these two cooling strategies takes preparation and organization. The first step is pre-cooling, which lowers body temperature before exercise begins, thereby increasing the body’s capacity to tolerate heat. Taking a cold shower or bath before leaving the house, travelling to the venue in an air-conditioned vehicle, sipping on a cold drink and cooling the skin with ice packs or cold towels are all pre-workout strategies proven to delay the effects of a warm-weather workout.  

For anyone heading out to the soccer pitch, golf course, softball field or tennis and pickleball courts, pack a cooler with ice packs and wet towels, placing them on your neck, torso and back as needed. Keep a spray bottle in the cooler and mist yourself during any break in the action. If you don’t have space for a cooler, buy a water jug and pack it with ice so you have enough cool water to drink, and towel off during any breaks in play. Have another water bottle filled with an ice slurry and sip it as often as possible, being careful not to gulp down copious amounts of cold water, which can produce cramps or bloating.

Keep warm-ups short with intensity dialled down to avoid overheating before the workout or competition begins. If you’re competing, reach out to organizers to see if they have instituted any hot-weather strategies, like extra timeouts to cool off and installing misters or a sprinkler, and whether shade is readily available.

Studies have shown that combining cooling strategies, like drinking ice slurries and applying cold towels to overheated skin, is the best one-two punch on a hot day. Using the same tried and true cooling techniques as Olympians will make exercise during a heat wave safer and more comfortable.

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