Tuesday, July 9, 2013

Exercise in Extreme Heat: Staying Safe While Training and Racing

By Dr. Lisa Colvin, PCG Elite Coach


Whether you're cycling, running, playing outdoors with your children, or working in your yard, take special care now that temperature have risen, particularly if it’s coupled with high humidity levels. As you’re now training and racing outdoors, use these common-sense precautions to prevent heat-related illnesses.

The Effects of Heat on Your Body

According to the U.S. Centers for Disease Control, exercising in extremely hot weather puts extra physiological stress on your body. Even when you’re riding and feel like the wind is cooling you off, take the temperature and humidity reading seriously. Both the exercise itself and the air temperature significantly increase your core body temperature. To cool itself, your body sends increased blood flow to circulate through the skin, leaving less blood volume for your working muscles, which in turn increases your resting and exercise heart rate. If the humidity is high, also, your body faces added stress because sweat doesn't readily evaporate from your skin, which pushes your body temperature even higher.

What Is Extreme Heat?

The CDC defines conditions of extreme heat as summertime temperatures that are substantially hotter and/or more humid than average for a particular location at that time of year. Humid or muggy conditions, which add to the discomfort of high temperatures, occur when a "dome" of high atmospheric pressure traps hazy, damp air near the ground. Extremely dry and hot conditions can provoke dust storms and low visibility. A heat wave combined with a drought is a very dangerous situation.

To protect your health and preserve your race when temperatures are extremely high, remember to keep cool and use common sense. The following tips are important for all cyclists:

1. Drink Plenty of Fluids

This seems like common sense, but it is interesting how many riders do not use this simple process to assist with cooling during outdoor exercise. In hot weather you need to increase your fluid intake, regardless of your activity level. Don't wait until you're thirsty to drink, because by then it’s too late; you’re already dehydrated, and your condition can turn into a poor physical outcome.

During heavy exercise in a hot environment, drink 16-32 ounces of cool fluids each hour. This is particularly easy to do on your bicycle. You can utilize water bottles (with insulated jackets) that keep the cool in the drink for some time, or you can freeze bottles and place them in your water bottle cages and in your jersey pocket. Warning: If your doctor generally limits the amount of fluid you drink or has you on a diuretic, ask how much you should drink while exercising in these extreme temperatures.

2. Replace Salt and Minerals

Heavy sweating removes salt and minerals from the body. These are necessary for your body and must be replaced. When you ride you can use a cool sports beverage of your choice that can aid in replacing the salt and minerals you lose in sweat. However, if you’re on a low-salt diet, talk with your doctor before drinking a sports beverage or taking salt tablets.

3. Sunscreen

Sunburn affects your body's ability to cool itself and causes a loss of body fluids. It also damages the skin and can be quite painful. When you train and race, protect yourself from the sun by putting on sunscreen with an SPF of 15 or higher (the most effective products say "broad spectrum" or "UVA/UVB protection" on their labels) thirty minutes prior to going out. Make sure the sunscreen you use has zinc oxide or titanium oxide in the ingredients; otherwise you’re wasting your time and money. Continue to reapply it according to the package directions.

4. Schedule Outdoor Activities Carefully

Try to schedule your training sessions in morning and evening hours. If you have to race in these extreme conditions, assure your safety by monitoring your power output, your heart rate, and the ambient temperature on your data collection device. If your heart rate is higher than normal for a given activity and/or your power outputs drops off, it is time for you for discontinue the ride/race and live to cycle another day.

5. Use a Buddy System

A buddy system is very simple to use for us cyclists, since we frequently ride together. When training in the heat, monitor your fellow riders’ condition and have someone do the same for you. If you’re riding alone, make sure someone knows where you’re riding and have some ID on you, in case you find yourself in an emergency situation. Heat-induced illness can cause a person to become confused or to lose consciousness while training and racing.

6. Adjust to the Environment

Be aware that any sudden change in temperature, such as an early summer heat wave, will be stressful to your body. You’ll have a greater tolerance for heat if you limit your physical activity until you become accustomed to the heat. If you travel to a hotter climate, allow yourself several days to become acclimated before attempting any vigorous exercise outdoors, and work up to it gradually.
NCEH’s Health Studies Branch offers the following tips to keep cool and use common sense:

  • Avoid hot foods and heavy meals; they add heat to your body.
  • Drink plenty of fluids and replace salts and minerals in your body. Do not take salt tablets unless under medical supervision.
  • Dress infants and children in cool, loose clothing and shade their heads and faces with hats or an umbrella while at your races.
  • Limit sun exposure during mid-day hours and in places of potential severe exposure.

Hot Weather Health Emergencies

Even short periods of high temperatures can cause serious health problems. During hot weather health emergencies, keep informed by listening to local weather and news channels or contacting local health departments for health and safety updates. Doing too much on a hot day, spending too much time in the sun, or staying too long in an overheated place can cause heat-related illnesses. Know the symptoms of heat disorders and overexposure to the sun, and be ready to give first aid treatment.

1. Heat Stroke

Heat stroke occurs when the body is unable to regulate its temperature. The body's temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. Body temperature may rise to 106°F or higher within ten to fifteen minutes. Heat stroke can cause death or permanent disability if emergency treatment is not provided.

Warning signs of heat stroke vary but may include the following:

  • An extremely high body temperature (above 103°F when measured orally)
  • Red, hot, dry skin (no sweating)
  • Rapid, strong pulse
  • Throbbing headache
  • Dizziness
  • Nausea
  • Confusion
  • Unconsciousness 

If you see any of these signs, you may be dealing with a life-threatening emergency. Have someone call for immediate medical assistance while you begin cooling the individual. Do the following:

  • Get the victim to a shady area.
  • Cool the victim rapidly using whatever methods you can. For example, immerse the victim in a tub of cool water, place the person in a cool shower, spray the victim with cool water from a garden hose, sponge the person with cool water, or if the humidity is low, wrap the victim in a cool, wet sheet and fan him or her vigorously.
  • Monitor body temperature and continue cooling efforts until the body temperature drops to 101-102°F.
  • If emergency medical personnel are delayed, call the hospital emergency room for further instructions.
  • Do not give the victim fluids to drink.
  • Get medical assistance as soon as possible.

Sometimes a victim's muscles will begin to twitch uncontrollably as a result of heat stroke. If this happens, keep the victim from injuring himself, but do not place any object in the mouth and do not give fluids. If there is vomiting, make sure the airway remains open by turning the victim on his or her side.

2. Heat Exhaustion

Heat exhaustion is a milder form of heat-related illness that can develop after several days of exposure to high temperatures and inadequate or unbalanced replacement of fluids. It is the body's response to an excessive loss of the water and salt contained in sweat. 

Warning signs of heat exhaustion include the following:

  • Paleness
  • Muscle cramps
  • Tiredness
  • Weakness
  • Dizziness
  • Headache
  • Nausea or vomiting
  • Fainting

The skin may be cool and moist. The individual’s pulse rate will be fast and weak, and breathing will be fast and shallow, even when exercise is stopped. If heat exhaustion goes untreated, it may progress to heat stroke. Seek medical attention immediately if any of the following occurs:

  • Symptoms are severe
  • The individual has heart problems or high blood pressure

Otherwise, help the person to cool off, and seek medical attention if symptoms worsen or last longer than one hour. Cooling measures that may be effective include the following:

  • Cool, nonalcoholic beverages
  • Rest
  • Cool shower, bath, or sponge bath
  • An air-conditioned environment
  • Lightweight clothing

3. Heat Cramps

Heat cramps typically affect cyclists who sweat a lot during training and/or racing. Sweating depletes the body's salt and moisture. The low salt level in the muscles may be the cause of heat cramps. Heat cramps may also be a symptom of heat exhaustion. Heat cramps are muscle pains or spasms—usually in the abdomen, arms, or legs—that may occur in association with strenuous activity.

If medical attention isn’t necessary, take these steps:

  • Stop all activity and sit quietly in a cool place.
  • Drink water and/or a sports beverage.
  • Do not return to strenuous cycling, because further exertion may lead to heat exhaustion or heat stroke. 
  • Seek medical attention for heat cramps if they do not subside in one hour.

4. Heat Rash

Heat rash is a skin irritation caused by excessive sweating during hot, humid weather. It can occur at any age. You may have seen cyclists in the Grand Tours wearing arm protection and using zinc oxide on their exposed skin. This is not uncommon to see in the Tour de France and can be affectively managed to allow training and racing to proceed. Heat rash looks like a red cluster of small blisters or pimples. It is more likely to occur on the neck and upper chest, in the groin, under the breasts, and in elbow creases.

If you experience heat rash, try to keep the affected area as dry as possible when not training or racing. While outdoors, the use of arm sleeves that protect but allow the skin to breathe is now a technique used frequently by susceptible riders. Use sunscreen that contains zinc or titanium oxide to best protect the skin when your race requires you to be in extreme heat. Heat rash typically usually does not require medical assistance.

Congratulations on your season so far, and good luck as you move forward!


Dr. Lisa Colvin is a professor of exercise physiology and the director of the University of Louisiana at Monroe (ULM) Human Performance Laboratory. Dr. Colvin is an elite coach with Hunter Allen’s Peaks Coaching Group and is a USA Cycling Level II, USAT Level II, ASCA Level IV, and USATF Level 1 coach and power-based training coach.  She can be reached at lisa@peakscoachinggroup.com or through www.peakscoachinggroup.com.

3 comments:

  1. Thanks Lisa! I get terrible heat rash on my arms and neck. I have sun sleeves but don't wear them after May as I thought it'd be too hot, I will definitely give that a try.

    When I saw the article title I rolled my eyes, so many heat related articles come out of northern states, so I was really excited when I saw it was written by you, as you are definitely in tune to the heat and humidity of the "real" south ;)
    Louise

    ReplyDelete
  2. Thanks Louise! From now until October will remain a training and racing challenge. If I would like more information, I would like to help!

    Lisa

    ReplyDelete