Exercise caution on hot summer days

Summer is a great time to be outdoors and get some exercise… but what about those extreme heat and smog alerts? If you’re planning to take advantage of good weather to stay in shape, here’s what you should watch out for:

Heat and humidity

Extreme heat can be dangerous enough without the additional strain of exercise. Even when you’re resting, your system has to work harder than usual to stay cool. When you exercise, your body produces more heat. Usually it compensates by producing more perspiration, which cools the body as it evaporates. However, high humidity levels means sweat doesn’t evaporate well because the air is already saturated with moisture. You’re losing fluids — but you aren’t cooling down.

Another way your body will try to get rid of excess heat is to send extra blood to the surface of the skin to cool it, which means less blood is reaching your brain, organs and muscles. You might feel light headed, confused and weak. When the environment is hot, the blood doesn’t have a chance to cool down.

In short, when your body can’t keep itself cool your internal temperature can spike quickly and you become ill. Heat exhaustion and heat cramps can have unpleasant short term effects, but heat stroke (the most serious of the heat-related illnesses) can cause permanent damage or even death if not treated properly and immediately.

Poor air quality

In many parts of the country, high temperatures are often accompanied by another related health risk: smog. Studies over the past few years have proven that smog can have serious short and long term effects. For instance, in Ontario alone smog is thought to be a contributing factor for 9500 premature deaths each year according to the Ontario Medical Association. Approximately 1000 of those deaths occur during or just after a period of increased pollution.

Long-term exposure to smog can reduce the immune system’s ability to fight off respiratory infections and can damage lung cells. Even short-term exposure for healthy people is enough to trigger symptoms such as burning eyes, difficulty breathing, headaches and exhaustion.

What does this mean for fitness? There’s a reason smog alerts warn against strenuous activity, especially during the middle of the day. When you work harder, you breathe harder than usual. When you breathe harder, you inhale more pollutants and they reach deeper into your lungs. Your lungs are also working at a diminished capacity, causing more stress on your body as it tries to get oxygen to your cells. Simply put, exercising outdoors during such conditions isn’t healthy.

If the risks of heat and smog have you wondering “why exercise at all?” you should know that a little caution and planning can help you enjoy the benefits of regular exercise while mitigating any risks. There are a number of things you can do to make your activities safer when the temperatures soar.


Tips for a safer exercise regime

Go early or late. Early morning and later in the evening are the best times to fit some exercise into your routine. The temperature isn’t as high and the sun isn’t at its peak. The levels of most pollutants in the air are lower before 8:00 am and after 8:00 pm.

Avoid overdoing it. Short periods of exercise can help avoid over-exertion, especially in the early summer when we’re not used to the heat. Studies have shown that three 10-minute exercise sessions have the same benefits as a full half hour, so splitting up your routine won’t cost you in the long run. Lighten up your pace and take frequent breaks if you’re exercising longer.

Listen to the weather reports. Keep an eye out for any warnings for your area, such as heat advisories, smog alerts or other dangerous weather. Local weather reports also provide valuable information like UV index and air quality reports.

Avoid urban areas. Most experts agree: the worst thing to do is walk, jog or cycle on city streets where exposure to heat and pollution from cars is at its worst — especially during rush hour. If possible, shady environments are preferable.

Dress the part. Lightweight, loose fitting clothing is best to allow for evaporation of sweat. A wide brimmed hat and sunglasses are a must, and choose waterproof sunscreen that won’t wash off when you sweat. If you’re in the water or near the water, bear in mind that it will reflect sunlight. Choose a high SPF sunscreen and don’t forget to reapply often.

Keep hydrated. Hot weather is the time to pay extra attention to your fluid intake when you exercise. How much do you need? According to the Cleveland Clinic, drink 8-12 oz. of water before you exercise (ideally 20-30 minutes beforehand) and then 6-10 oz. for every 20-30 minutes of exercise, and another cup when you’re done. Drink plenty of water, even if you aren’t feeling thirsty.

Work out indoors. It’s sunny and warm, so who wants to be inside? You do, actually. Moving your workout indoors means cooler temperatures, better air quality and reduced humidity — conditions which make it easier to breathe and maintain a normal body temperature. You can stop whenever you want, and there’s often ready access to water, first aid and a phone.

If gyms or health clubs aren’t for you, look for drop-in classes and fitness swims at your community’s recreational centre. Many of these activities are pay-as-you-go rather than membership-based, so you’re not losing money when you don’t attend. Many facilities offer free access to walking tracks during the summer and early fall too. Check with your city’s recreation guide for more information.

Try something new. You won’t notice the temperature as much participating in swimming, aqua aerobics and water sports because cool water will take heat away from your body. Also, try a “gentle” activity such as yoga or tai chi to focus on strength and flexibility instead aerobic activity. Many gyms and studios offer special deals on these types of classes during the summer.

Know the warning signs and listen to your body. The most important thing you can do to safe guard your health is to stop and rest if you don’t “feel right.” Be on the lookout for the signs of heat-related illnesses, smog exposure and dehydration. The Mayo Clinic’s online First-Aid Guide covers the symptoms and treatment for heat exhaustion, heat stroke and heat cramps. Smog may be affecting you if you experience difficulty breathing, coughing, eye or throat irritation and fatigue. Any serious symptoms require emergency treatment.

You may want to take a pass if you aren’t feeling well. Smog can aggravate allergies or make a cold feel much worse, and you’ll be more susceptible to the effects of heat if you have a fever or are taking medications for a cold or virus.

Have a plan. Be proactive if you have any pre-existing health conditions and speak with a doctor about adjusting your fitness routine. Heart and breathing problems will be worse on heat and smog alert days, so it’s best to plan ahead to deal with any problems. Your doctor can also warn you if any medications you are taking will put you at increased risk such as blood pressure and heart medications, allergy pills, cough and cold remedies and thyroid pills.

Overall, exercise need not be shunned completely if you plan carefully, educate yourself about the risks and employ caution.

Centers for Disease Control: Extreme Heat
Cleveland Clinic: Exercise and the Heat
Health Canada: Extreme Heat Events
The Lung Association: Smog Smart Strategies
Toronto Public Health: Outdoor exercise during heat and smog alerts (PDF)