Hot, humid weather can place significant stress on the cardiovascular system. Bright sunlight, high humidity and lack of wind and shade challenge the body’s ability to dissipate heat and maintain a normal body temperature. The mechanics of it are simple: under extreme temperatures, the heart has to beat faster than usual to pump blood to the surface of the skin to assist with sweating to cool the body. This causes strain on the heart. Too much of it – and not enough cooling – can cause damage to vital organs, leading to a potentially fatal condition known as a heat stroke.
Heat stroke can happen to anyone, but those with cardiovascular disease are at greater risk, explains scientist Jennifer Reed, PhD, program chair of cardiac rehabilitation and director of the Exercise Physiology and Cardiovascular Health Laboratory at the Ottawa Heart Institute.
“Patients with heart disease including heart failure and hypertension are at increased risk of heat-related illnesses, especially during exercise or vigorous levels of physical activity,” says Reed.
Reed warns that patients who are prescribed medications to manage their disease may be at elevated risk. “Medications such as beta-blockers which lower heart rates may limit the amount of blood that is redistributed to the extremities and skin for cooling. Research has also shown that blood vessel dilation is impaired in patients with heart failure.”
Patients are advised to talk to their doctor about how their medication may affect their heart in extreme heat.
The Ottawa Heart Institute encourages everyone to follow these important tips below to keep cool this summer.
Here are six tips to avoid heat related injuries.
1. Drink plenty of water to keep your body hydrated
Reed says drinking water before, during and following exercise in the heat is important to maintain good hydration. She recommends drinking approximately 3 to 8 oz of water (a 'gulp' of fluid is about 1-2 oz) every 15 to 20 minutes during exercise.
2. Avoid vigorous, high-intensity activity in extreme heat conditions
Reed says exercising in an air-conditioned or well-ventilated facility or in a cooler, shaded area is best for hot days. “Or, better yet,” she said, “find a pool or beach to keep cool, swim laps and have fun!”
3. Wear comfortable, light-coloured, loose-fitting clothing to help you stay cool in the sun
Reed says wearing shorts and a t-shirt exposes the skin and encourages heat loss from sweat. She recommends wearing materials such as cotton that wick sweat to the surface to help with heat loss.
4. Wear sunscreen and a hat
Reed says sunburns make it more challenging for the body to cool itself. It is best to apply sunscreen up to 40 minutes before sun exposure to get the best results.
5. Be aware of the symptoms of heat injury
Chills, nausea, dizziness, weakness, fainting, and profuse sweating are all warning signs of heat exhaustion and heat stroke. If you experience any of these symptoms, find a cool shaded area, relax and drink plenty of water and, if you’re feeling unwell, consider returning home to rest.
6. Don’t be shy to ask for help
If you need a fan, to borrow some sunscreen, a cool place to stay – or anything else to help beat the heat – ask a friend or family member for help.
For more information:
- To learn more about how you and your family and friends can maintain a heart-healthy lifestyle this summer, consult the Ottawa Heart Institute’s Prevention and Wellness Centre.
- Explore practical prevention and rehabilitation tips to help you stay active, healthy, and heart-smart all season long.
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