Exercising Safely in the Heat
As the temperature outside rises it is important to consider how exercising in the heat effects our body and its ability to thermoregulate or control your body temperature. When exercising due to inefficiencies in metabolic transfer more than 75% of the energy generated from skeletal muscle is liberated as heat (1). Our bodies are normally extremely efficient at dissipating this additional heat though several mechanisms such as, vasodilation of the small blood vessels near the skins surface and an increase in sweating (2). However, when the ambient air around us becomes hot and humid it can have a serious impact on our bodies ability to dissipate heat and can lead to an increased risk of heat related injury or illness (1).
The body has four ways of naturally cooling the body they are:
- Evaporation: Our bodies sweat and then the sweat evaporates creating a cooling effect. When temperatures get hot and humid the temperature and the amount of water in the air is high preventing sweat from evaporating. Thus, the body sweats more in attempt to reduce body temperature. During exercise this is the main way our body tries to cool itself.
- Radiation: is how the body loses heat to the atmosphere or objects around us through infrared rays. This occurs with out coming into contact with another object. An example would be the heat you can feel coming off the oven when you are cooking. This is the main way we discharge heat at rest.
- Conduction: Is the process of losing heat by physically coming in contact with another object. Putting an ice pack on your body or a cool cloth on the forehead would be examples.
- Convection: Is the process of losing heat when air or water moves around us. Cooling by convection occurs when swimming in cool water, taking a cold shower or standing in front of a fan.
5 Tips for staying safe while exercising during the heat:
- Make sure you are well hydrated
When exercising in hot weather it is particularly important that you stay well hydrated. As we become less hydrated our bodies become less able to deal with the demands placed on it and therefore become more susceptible to heat related injury. Did you know that drinking cold water when it is hot outside can help to reduce your body temperature?
- Adjust the level you are exercising at
If you are not accustomed to or acclimatized to exercising in the heat, consider working at a lower level than you normally do. This may mean running at a slower pace or covering less distance. But can also apply to any form of exercise including weightlifting.
- Consider where and when you are working out
If you normally work out in the middle of the day or in an enclosed room with no air conditioning you will want to adjust your routine. If your running route is in full sun, consider changing your route to a shadier one. Working out first thing in the morning or later at night can also help alleviate some of the stress from heat. Turning on fans, opening doors or working out in a different area (i.e., Shady outdoor area or air-conditioned room) can also be helpful. Just remember to be always exercising Safely in the heat.
- Clothing/ hats and sunscreen
When working out in the heat it is important to consider your clothing. Wearing lose fitting breathable clothing and light colours can help you stay cool. If you are going to be in the sun wear a hat and sunscreen as heat related illness can occur from exposure to the sun and heat even in the absence of exercise.
- Know your limits
When it is hot outside is not the time to start testing your limits. If you are not accustomed to working out in the heat do not try to run faster, farther or lift more weight than you normally do. Your body may respond in a way you were not expecting. Similarly, if you normally run 1 km in 6 minutes and in the heat, it is taking you longer this should be a good cue that the body is under stress from the heat and you may need to dial the amount of exercise back. Running indoors on a treadmill in an air conditioned room can be a good alternative.
- Try something new or switch it up
When its hot outside this can be a great time to try something new. Swimming can be great exercise while helping you stay cool. Running through the sprinkler, having a water balloon fight or anything that can help you stay cool while being active and having fun are great alternatives to your usual activity. Be sure that you are still hydrating as you can become dehydrated even when in the water.
Exercising Safely in the Heat
A final thought on staying safe in the heat:
Some groups are at higher risk of heat-related illness this includes young children, people with chronic illness and the elderly. These people should take extra precautions in extreme heat. Below is a chart from the Center of Disease Control and Prevention on the different types of heat related illnesses and their signs and symptoms and what to do if you believe you or someone you care about is developing a heat related illness.
Clinical Exercise Physiologist