Exercise in the heat: The good and the bad
Written by Jared Kauffman:
The Good:
There is a lot of time and energy spent on educating people on the dangers of exercising in the heat but there ARE some of great benefits to exercising in the heat! The heat is not all bad and here’s what you should know:
In hot and humid environments there is a natural rise in body temperature even before you begin your workout, decreasing the time it takes your body to warm up and reach on optimal internal state for workout.
For every degree celsius that your body temperature increases, your heart rate increases approximately 10 beats. A faster heart rate means more blood being pumped to your muscles which equals more oxygen and nutrients getting to your muscles.
Increased temperature causes dilation of blood vessels, which again causes more blood and nutrients to reach the areas they need to go.
Increased muscle temperature also aids in extensibility. Think about a rubber band; put it in the freezer, stretch it and it breaks, put it in a warm environment, stretch it, and it stretches much farther than it did at room temperature. (Now you understand the benefit of hot yoga!)
Lastly, less related to exercise, an increased body temperature has been shown to help the immune system work better. This is the same idea behind a having a fever when you are sick!
The Bad:
However, with the reward comes some risk. It is no secret that exercising outdoors too long in the heat can be dangerous. Next week, you’ll take a look at the common dangers of exercising in the heat. And how to make sure you stay safe.
When talking about temperature regulation in the heat, there are a few things you need to be aware of about temperature and humidity.
The body’s main defense against rising internal temperatures is to sweat.
The evaporation of the sweat off the skin cools the body off.
An issue occurs with this process when the temperature and/or the humidity are high enough that sweat does not evaporate.
At around 60 percent humidity, evaporation is inhibited, and around 80 percent humidity it stops altogether.
The most common dangers of exercising in the heat are dehydration from excessive sweating, and hyperthermia either from your body running out of sweat, or the humidity being so high that the sweat does not evaporate. It is important to stay well hydrated! When your body becomes excessively dehydrated, blood volume decreases so much that the circulatory system can stop working. When the body cannot cool itself down, due either to dehydration, or a too high level of humidity not allowing the water to evaporate, heat stroke can occur.
The Ugly
There are three stages leading to heat stroke:
Heat cramps - isolated or multiple muscle cramps or pains, and can be treated with fluids and moving into a cool environment.
Heat exhaustion - characterized by profuse sweating, slightly elevated body temperature, nausea, dizziness. Heat exhaustion can quickly become heat stroke and should be treated as a medical emergency.
Heat stroke - characterized by lack of sweating, very high body temperature, loss of consciousness, rapid and strong pulse. If heat stroke is suspected, call 911 immediately.
