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In a summer of repeated high heat advisories delivered with warnings to curtail outdoor exercise, how cautious do we really need to be when working out during a heat wave?

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Short workouts of moderate to low intensity may feel uncomfortable when the temperature soars, but most regular exercisers are unlikely to be impacted beyond moving a little slower and collecting a little extra sweat on their brow. But the longer and more intense the workout, the more the body struggles to regulate the one-two punch of the internal heat generated through exercise and the external heat of a hot summer’s day.

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In more temperate conditions, the body’s internal cooling process does a pretty good job of managing the increase in core temperature occurring during a tough workout. But add any combination of unrelenting sunshine, high heat and humidity, and that previously trusty cooling system can’t keep up.

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Some folks find it easy to change up their workouts to accommodate the heat, heading to the pool, exercising in the early morning or evening or modifying their schedule to allow for a rest day. But for team sport athletes (soccer, football, etc.), those with rigid training schedules (athletes training for competition) or athletes scheduled to compete, waiting out a heat wave isn’t an option. Hence the need for cooling strategies to lessen the effects of extreme summer weather.

Exercising and competing in the heat has been well-studied and well-tested in the field by elite athletes who work out regularly in hot climates. Most mitigation strategies focus on reducing the temperature of the skin and core and are easily adopted by the average exerciser and weekend warrior. Some tactics are best implemented in advance of physical activity, while others are designed for just before or during a game, competition or workout.

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Getting the body acclimated to the heat is the first step in making sure summer workouts don’t escalate from being uncomfortably hot and sweaty to something more serious, like heat stroke, heat exhaustion or heat cramps. Start by ramping up the cooling mechanisms already in place by performing short, controlled bouts of exercise in the heat of the day. Within five to 14 days your body will sweat more and earlier and start producing a less salty concentration of sweat, which helps preserve the balance of electrolytes. Once you feel that extra sweat response kick in, you can slowly increase the duration and intensity of the workout commensurate with the heat and humidity.

Sweat is an important component of the cooling process, as it moves excess heat away from the body’s core. But producing more sweat means it’s imperative to replace lost fluids with water. Dehydration puts stress on the heart and reduces blood flow, which impairs the cooling that occurs when the blood moves from the body’s core to the periphery. Increasing water intake is crucial, but how much you need to drink is less clear.

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There is an ongoing debate between drinking ahead of thirst and only when thirsty, with pros and cons associated with each strategy. If you wait too long to start replacing fluids, it may be tough to catch up. But if you drink too much, your internal body chemistry gets out of whack, which causes your body to retain water, resulting in its own set of serious health consequences.

The best option is to start your workout well hydrated, after which you can incorporate a drink-when-thirsty strategy, which should minimize the loss of body fluids in the heat. If you want to further enhance cooling, consider sipping on an ice slushie (ice crushed in a blender) before you lace up your shoes. Pre-cooling is one the newest strategies employed by athletes who have no choice but to exercise or compete in the heat. You can also opt for a cold shower or bath prior to pulling on your workout clothes or put on a cap you’ve had chilling in the freezer before heading out the door.

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Even the best pre-cooling strategies last only about 25 minutes, after which you need to move onto the next round of tactics. If you’re playing sports and can make it to the sidelines, have a cooler filled with ice packs and/or wet towels that can be applied on the neck and limbs. You can also fill a spray bottle with icy cold water and mist yourself to cool off. Endurance athletes like runners and cyclists might find it harder to incorporate mid-workout cooling strategies but planning routes that allow refilling a water bottle and the occasional head dunk under a tap or in a sprinkler can keep you rolling on a hot day.

Whatever strategies you adopt, remember it’s all about cooling the body from the inside out and the outside in — keeping internal body temperature from rising and your skin cool enough to reduce the discomfort associated with exercising in the heat. Summers are getting warmer, so the sooner you become adaptable to the heat the more comfortable you’ll be.

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