How to stay cool this summer Feelin' hot, hot, hot? An exercise physiologist explains what happens to your body when it’s warm outside—and offers his top tips for staying cool. By Kate Daley Thinkstockphotos.ca When it's hot and humid out, it's all too easy to skip your workout and stay indoors to enjoy the A/C. But getting outside in Mother Nature can have positive psychological and physical benefits. Greg Wells, an associate scientist in Physiology and Experimental Medicine at The Hospital for Sick Children in Toronto, gives his hot-weather rules for your workout. How does the body adapt to hot weather? The body cools itself through sweating, explains Wells. As your blood circulates through your muscles and internal organs, it heats up. Then, when that hot blood reaches the skin, your sweat glands open and release moisture; as the sweat evaporates, heat gets pulled up and out of the body. Your body has to work extra hard in the summer to pump enough blood to produce sweat. Wells' rules for handling heat: 1. Embrace it. The body adapts to whatever conditions it's consistently exposed to, says Wells, so don't overdo it early on in the season before your system has adapted to the hot temperatures. As the weather heats up, spend small increments of time outside to help you acclimatize, spend small increments of time outside to help you acclimatize or try turning off your air conditioning during the day and use it only at night to help you sleep. 2. Wear light-coloured clothing. Dark colours absorb heat, whereas light colours reflect it. This is especially important if you're outside during peak sunlight (between 12 p.m. and 2 p.m.), or if you're in the sun for prolonged periods (playing a round of golf, for instance). 3. Pay attention to your body. A run in warm weather forces your heart to work harder—not only does it have to meet the demands of exercising, it has to provide energy for cooling the body. Accordingly, it takes less effort to achieve a higher heart rate in summer. Invest in a heart rate monitor to ensure you're staying within a safe zone. Instead of a long cardio workout, try high-intensity interval training. You'll spend less time outside while getting the same physiological benefits. If you start to feel fatigued or have muscle cramps, drink water with electrolytes and go inside and cool down. 4. Sweat it out. If you're not hydrated, you can't sweat, and if you can't sweat, your body can't properly manage heat. Drinking water helps you manage your internal temperature, says Wells. But beware of humidity: sweat doesn't evaporate as quickly in humid conditions, making it harder for the body to cool down. 5. Keep an eye on the kids. Children don't sweat as efficiently as adults, so they're particularly susceptible to hot, humid conditions. Practise preventive hydration by making sure children take drink and snack breaks. Dress them in light-coloured clothing and monitor them closely for muscle cramps, dizziness, nausea, or headaches.