Exercise Can Be Done Anytime
It's July and a heat wave is on. You are used to exercising and enjoy your daily run, but the paper says that the heat index will be up today and to stay indoors during the elevated temperatures. What do you do? This is a common scenario in the state that I live in. In Texas, sixty to ninety days of each summer the temperatures soar above 100 degrees, and a ninety degree day is considered a "cold front".
Can Have Many Effects
Exercising in the heat can have many effects. When you are exercising, your body's muscles burn glucose as its fuel. This fuel burning will cause your body temperature to rise while you are exercising. Your body will also increase the blood flow to the skin, and begin sweating in response to this increased internal temperature.
Sweat Cooling
Exercises in the heat also does something else to your body. The sweat cooling by evaporation is how your body tries to cool itself off. But if the amount of heat produced is more than the evaporation of sweat can handle, or the weather is humid, which means that the sweat evaporates more slowly, the body's internal (core) temperature will rise and thermal, or heat injury, can occur.
Thermal Injury
This is more likely in hot weather, and extra caution is needed. Normally, a person who exercises and is in good condition can handle temperature ranges of 65 to 85 degrees, but as the temperature rises, special precautions need to be taken. Also, the more strenuous the activity, the greater the risk of heat related problems. With hot, humid weather thermal injury can begin to occur in 12 to 15 minutes after starting strenuous exercise (such as competitive sports, running, or biking up a hill).
Work Up Gradually:
How do you help your body stay cool enough when you are exercising in a hot climate or during the summer? The following ideas will help.
It is important to acclimate your body gradually to higher temperatures. This means take it easier and exercise for a shorter period of time when the weather is hot and humid. Cut back your normal routine as the thermometer rises, and then gradually work back up to a longer workout over the next few weeks. As a dedicated exercise enthusiast, and also a registered nurse, let me share the tips that I have learned for exercising during hot weather.
Look For The Shade
Warm up in the shade, doing your stretches there, if possible. Over time the body's core (internal) temperature will drop during exercise and the metabolic rate at rest will decrease as it acclimates to the heat. Your body will also learn to sweat more in response to exercise, helping to cool itself off. Try to exercise in the shade as much as possible by choosing shady tree lined streets for walking and jogging.
Time of day Counts
Exercise when the temperature and humidity are both high, since this increases the risk of hyperthermia so don't. This means that when the outdoor temperature is above 90 degrees F. and the humidity is above 75 % you should exercise inside, such as at a mall or health club, or only during the coolest parts of the day, such as early morning or late evening.
Avoid High Heat Hours
Avoid the hours of 10:00 a.m. to 2:30 p.m., when temperatures tend to soar. Listen to the heat indexes on the radio since they will also be a guide to how hot it feels to your body. A special caution: as a person ages, their ability to regulate body temperature decreases, and this precaution becomes doubly important.
Dress For The Heat
Minimal, loose fitting clothing that is comfortable will help promote heat loss and evaporation. Light colors and clothing made of cotton or sweat wicking fabrics are best. Avoid open-mesh jerseys and tank tops, since they will cause overexposure to the sun. A brimmed hat can help shade your face. And always use a good sunscreen product with a SPF of at least 15 (waterproof is best since you will be sweating) to prevent sunburn. A wet bandana or ice pack scarf around the neck can also help with staying cool.
Drink Up
One of the biggest risks of exercise in hot weather is dehydration. For this reason it is important to drink plenty of WATER while exercising. In hot weather, it is a good idea to drink plenty of water (two eight ounce cups) an hour or two before starting to exercise. Follow this with another cup every 20 minutes during exercise and an additional cup or two within a half hour after exercising. The body can lose up to a quart of water an hour while exercising, so drink up, even if you don't feel thirsty. Your body needs the extra fluid.
Avoid Sodas
Exercising or if you are competing strenuously, more than 90 minutes, a fluid with 5% to 8% carbohydrate, and minimal electrolytes, such as Gatorade or Powerade is okay. Avoid sodas, since they will tend to dehydrate you more (caffeine is a diuretic) and the fluid replacement is inadequate.