Exercising in the Heat of Summer

While some of my favorite summer activities include water – swimming & paddle boarding – that doesn’t mean I stop running, biking, or playing tennis. Longer days and steamy temperatures just mean I need to be smarter about it. Our bodies need time to adapt to the increased physiological demands of training in the heat, and even if you’re an avid exerciser, avoiding heat-related illnesses takes preparation and planning.

What are heat-related illnesses?  As you’ll see in the handy chart below, they include heat cramp, heat syncope, heat exhaustion, and heat stroke.

I honestly feel like we went from 70 degrees to 90 overnight. So it may take a few weeks for the body to fully acclimate. Be OK with doing a little less for a bit. Maybe you take shorter runs or bike rides, breaks along the way, or just get outside at a cooler part of the day. Early mornings are my favorite because they’re often less sticky than evenings. It’s important to note that heat-related illnesses generally have a greater affect on those with lower levels of fitness. So if you are starting a new fitness routine, go slowly and build up intensity gradually.

Staying hydrated is one of the keys to preventing heat related illness, as inadequate hydration decreases the body’s sweat rate. Your body needs to be able to sweat in order to cool itself off!  If you plan on training outdoors for extended periods of time, be sure to have access to water and/or a high quality sports drink. Some signs that you are dehydrated include headache, dry mouth, dizziness, and decreased energy. And it’s not just during exercise that you need to hydrate – remember to replace the water you lost while you were exercising after you’re finished. If you’re urine is a medium to dark yellow, or you’re down a few pounds immediately after exercising, chances are you need to hydrate.

Bonus – most fruits and veggies are high in water content and make a delicious way to help keep the body hydrated! Side note – carbonated beverages may ‘quench’ your thirst, but they are not as hydrating as non-carbonated beverages.

Did you know that evaporation of sweat is the body’s key mechanism for staying cool? And that humidity decreases the rate of sweat evaporation, as can wearing too many clothes? Wearing loose fitting, weather appropriate gear will help prevent your body from overheating, and moisture wicking fabrics will increase the rate of sweat evaporation over less permeable materials. I know some people like to wear sweat pants and sweat shirts while exercising in order to ‘sweat off the pounds’.  What they are really doing is sweating off water weight and creating an unsafe level of heat for their bodies. I do not recommend this at all.

Heat can also affect children differently since their thermoregulatory systems are not completely developed, and they have a delayed response and limited ability to sweat. It is important to give them more rest breaks, extended warm-ups and cool-downs when they are playing sports, and frequent reminders to hydrate.

Heat-related illnesses are preventable, but can become life threatening in just a matter of minutes. Review the signs, symptoms and care of heat illnesses so that you can quickly identify and appropriately respond to these potential medical emergencies. Happy exercising!

Heat Illness Signs and Symptoms* Immediate Action
Heat Cramp Muscle spasming and cramping that occurs during or after exercise, especially common in the calf. Stop activity, hydrate, apply pressure or begin gentle stretching, massage of muscle.
Heat Syncope Headache, nausea, dizziness, tunnel vision, fainting Move to shaded area, hydrate, elevate legs, and monitor vital signs.
Heat Exhaustion Collapse, possible loss of consciousness, heavy sweating, dizziness, fainting, slightly elevated body temperature, shallow breathing, headache, weakness, thirst, nausea, vomiting, cool, wet skin Move out of sun and heat, force to hydrate, elevate legs, remove excess clothing and equipment to cool with fans, wet towels, ice packs. Refer to a physician.
Heat Stroke Skin is dry, hot or flushed, body temperature is elevated (104+), behavior change, confusion, headache, labored breathing, unresponsiveness, seizures, coma. Treat as a medical emergency and transport to hospital immediately (activate emergency medical system). Remove excess clothing and equipment, begin cooling immediately starting at the head and moving down the body, using ice packs, fans, cold water focusing on major vessels (armpit, neck, groin).
*Not all individuals will have all the signs and symptoms.
Adapted from Powers and Howley, 2012, Exercise Physiology 4th ed. and NATA’s Position Statement: Exertional Heat Illnesses.


Adapted from National Academy of Sports Medicine Blog: https://blog.nasm.org/fitness