Kenneth Gardner

Dear Mr. Gardner,

Your article in The Gleaner dated October 19, prompted me to send this email. I exercise almost daily. There are times at the end of my workout or prior to cooling down that I can feel the heat coming out of my body. Is this normal? What causes it?

What exactly is happening in my body at that time?

Marcia

Response to reader

Dear Marcia,

Many chemical reactions occur in our bodies causing changes in body temperature during exercise.

It is normal for our bodies to produce heat during our exercise routine. Body heat is a by product of the glucose that our body breaks down to provide us with energy to carry out the exercise.

With heat being the by-product of the chemical reactions in the body, the heat production is proportional to the number or rate of chemical reactions. The measurement of the heat generated by the body is a reflection of the rate of body responses to exercise.

The heat that the body produces during exercise in combination with the heat stress from the environment can also increase the experience of excessive body heat. Changes in your body temperature are mostly due to your body's chemical reaction to the heat load of the exercise. As the exercise intensity increases your body temperature will rise. The actual body temperature response is influenced by the fitness of your heart and lung and your degree of acclimatisation to heat exposure.

As you lose water during the exercise your body becomes dehydrated, your sweat rate decreases and your body temperature increases. Persons with a greater increase in body temperature and heat rate are likely to be less tolerant of exercise in a hot environment.

Improve heat tolerance

We can improve our heat tolerance after we have done endurance exercises in a hot environment. As you do more intense exercise routines your heat load becomes greater. In time you will adapt to greater heat load and similarly benefit in your acclimatisation.

One of the best methods to decrease your risk of developing a heat problem or injury is to gradually acclimate yourself to exercising in hot environments. Through this process, your heart rate and body temperatures, at a given exercise intensity, decreases. The first such session may last for as little as 10 to 15 minutes for safety reasons. You can then gradually increase the duration to 20 to 60 minutes. It takes most healthy persons 10 to 14 days to fully acclimate to hot environments.

The benefits of heat acclimation are lost quite rapidly when you stop exercising in the heat. With each two days of abstaining from heat exposure one day acclimation is lost. After three to four weeks without heat exposure you would be considered as not acclimatised.

Heat from fats

Your diet will also influence the amount of heat that your body produces. Carbohydrates and fats are our main sources of energy supply. Fats are basically twice as rich in their energy content compared with carbohydrates. Thus, a diet that is providing a greater amount of energy from fats is also likely to increase the production of heat during exercise. This will happen especially if the exercise is done at a moderate pace where fats are used more readily than carbohydrates for energy production.

The experiences that you are having are quite normal. These experiences are also indicative of the work that your body is experiencing from the exercise. From these experiences, you can expect improvements in your health and wellness.

Kenneth Gardner is an exercise physiologist at the G. C. Foster College of Physical Education: email: yourhealth@gleanerjm.com.