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The Hot Zone
Avoiding Heat Injuries.
Heat injuries are not uncommon in anyone who spends time outside. Endurance athletes are particularly prone to these types of injuries because they tend to ignore the subtle signs that could be the prelude to a medical disaster. Heat injuries can occur anywhere in the world (even in cold weather), but it is obvious that the hotter and more humid the weather, the greater one’s chance of sustaining a heat injury.

Sunburn

Sunburn is more than just uncomfortable; it can take you out of competition, not to mention setting you up for serious skin problems as you age. It would be a good idea to understand what causes sunburn so one can see how and why one needs to prevent sunburn.

thehotzone
Heat injuries during competition range from the very minor to the very serious; prevention is key.
Ultraviolet (UV) radiation from the sun is what causes tanning and associated skin damage. There are three types of UV radiation: UV-A, UV-B, and UV-C. UV-A is the predominant UV radiation that reaches Earth, while UV-B is the most biologically active radiation. UV-C is generally completely absorbed by the ozone layer, so its effects are minimal. Although UV-A is less carcinogenic on a dose-for-dose basis than UV-B, ten to one hundred times the amount of UV-A radiation reaches Earth than UV-B. Together with UV-B, UV-A can be a significant factor in causing damage to the skin.

Melanin is the pigment that gives the skin colour. Dark-skinned people have more melanin in their skin than do light-skinned people. As a light-skinned person is exposed to the sun, the cells produce more melanin in an attempt to protect the skin. That is why most light-skinned people are darkly tanned after prolonged (weeks to months) exposure to the sun. As the years pass and the individual continues his or her sun exposure, changes occur in the skin: it becomes thicker and wrinkled. Changes can also occur on the cellular level, and these cellular changes can evolve into skin cancer.

Sunscreens
The best way to avoid the health risks associated with sunburn is to prevent it in the first place. According to the Canadian Dermatology Association (Association canadienne de dermatologie), one should look for a product with a minimum sun protection factor (SPF) of “15” to protect against the sun’s UV-B rays. The product should also contain ingredients that protect against UV-A rays that penetrate more deeply into the skin, are responsi¬ble for premature aging, and contribute to the development of skin cancer. Sunscreens that are labelled “broad spectrum” help protect against both. Sunscreens with a chemical called Mexoryl SX, that protects against both UV-A and UV-B rays, are available in Canada and Europe (but not in the United States) and have been shown to prevent or reduce skin sagging in mouse models.

Unfortunately, the U.S. does not allow the new and better sunscreen ingredients for UVA light protection. The American Food and Drug Administration (FDA) issued new labelling regulations in 1999 for over-the-counter sunscreens. According to the 1999 FDA guidelines, sunscreens sold in the United States are prohibited from making claims on their labels that are considered unproven or absolute such as “waterproof” and “all-day protection.”

The FDA warns that sunscreens should not be used to prolong one’s time in the sun; even with a sunscreen, one is not going to prevent all the possible damage that can be caused by the UV rays. The FDA proposed limiting the SPF values on a sunscreen label to “30”; products with an SPF value above “30” would be labelled “30+.” Two reasons were given for this action: there were limitations in testing methods for products with “SPF 30+” formulations, and concern that values above “SPF 30” may lead consumers to believe that they can spend more time in the sun than they should.

Chemical sunscreens absorb the dangerous wavelengths of radiation and convert them to a lower energy state, decreasing the chances of cellular damage. Although the use of a sunscreen with the highest SPF is encouraged, sunscreens with an SPF of “15” may block about ninety-five per cent of the harmful rays. Inadequate usage of sunscreens is very common. Apply a generous layer of sunscreen to all parts of your body that will be exposed to the sun; it takes about one ounce to cover the entire body. Most people use far too little sunscreen and get only a fraction of the protection it can provide.

Medications, both prescription and over the counter, can sensitize one’s skin to sunlight. Sulfur-based antibiotics, antihistamines, water pills (used to control high blood pressure), and many others can cause sensitization, so check with your health-care provider about sun exposure if you are prescribed these medications.

Endurance athletes would be wise to be aware of the side effects of medications. Some medication may not only make you sun sensitive but also affect the way your body metabolizes water. This may affect your stamina.

Treating sunburn
So you were out in the sun all day, and now you’re sunburned. What can you do about it?

If it’s a mild sunburn, take some ibuprofen or aspirin and sit in a cool bath. Ibuprofen and aspirin are anti-inflammatory medications, so either will decrease the pain and possibly some of the redness. The cool bath won’t do anything from a medical point of view; it just feels good. The pain should subside soon, and the redness will resolve in several days.

Severe sunburn is treated in a totally different manner. Severe sunburn involves the deeper layers of skin, accompanied by more pain.

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Chills and low-grade fevers are not uncommon. “Sun poisoning” is a term some use to refer to the systemic effects of the release of the chemical mediators produced by the sun-damaged tissue. After several days to a week, blisters develop (this is the damaged skin layer dying off), and the dead skin then sloughs off. There is nothing you can do to prevent blisters or the dead skin peeling off other than to prevent the sunburn in the first place. If nausea, vomiting, or fever develops, make an appointment with your health-care provider. And next time you’re out in the sun, or even a bright but overcast day, use the sunscreen. Chances of getting skin cancer may be related to the number of times someone is sunburned.

Other Heat Injuries

Sunburn isn’t the only problem you need to be aware of when competing. Prolonged exposure to high temperatures and the high exertion levels that endurance athletes experience can lead to dehydration, which can be an insidious process. This can result in heat exhaustion, heat cramps, or heatstroke. Heat cramps and heat exhaustion just make you miserable, but heatstroke can kill you.

Heat cramps
Heat cramps are caused by an excessive loss of sodium chloride (common table salt) by profuse sweating during strenuous activity at high temperatures. Sodium chloride is needed to maintain the water balance in the body and to maintain blood pressure. The problem is compounded if the humidity is also high; since the humidity prevents the sweat from evaporating, one continues to sweat in an effort to keep cool.

Heat cramps usually occur in those people who are not acclimatized to hot and dry climates where excessive loss of fluids is undetected because of rapid evaporation of the sweat.

The onset of heat cramps is abrupt, with the muscles of the arms and legs usually affected first. Severe spasms and pain occur, along with knotting of the muscles. The pain can then spread to the abdominal muscles. Fatigue, malaise, and nausea can accompany the cramps.

Treatment of heat cramps is simple and straightforward. Move into the shade and drink sips of water with some salt added or perhaps a sports drink that contains sodium chloride. Recovery is usually rapid and uneventful, but refrain from competing for several days.

Heat exhaustion
Heat exhaustion occurs when one rapidly loses too much fluid. Heat exhaustion can be brought about by the same things that cause heat cramps: excessive sweating, diarrhea, and vomiting, for example. The problem with heat exhaustion is that the blood thickens slightly and the heart doesn’t fill as efficiently, so the pulse becomes weak. Because of the lack of proper circulation, the brain doesn’t get the blood it needs, which means that the person can become confused, agitated, and sometimes even violent. It is not uncommon for a person suffering from heat exhaustion to become unconscious.

Prevention is the key. Ideally, one should stay in the shade and avoid exertion, but since that’s not an option for endurance athletes, drink plenty of water; if it’s a hot day and exertion levels are high, two-to-three gallons a day may be needed to avoid a heat injury. Lightly salt your food to replenish salt lost through perspiration.

Heatstroke
Heat stoke is the most severe and worrisome of the heat injuries. It is very rare, but it is a serious medical emergency. If not treated immediately and appropriately, death or serious brain damage can result. Heatstroke occurs when the mechanism that regulates the body’s temperature shuts down completely, allowing the body’s temperature to skyrocket as high as 104 degrees Fahrenheit to 106 degrees Fahrenheit. The skin is hot, flushed, and usually dry. The person will usually become unconscious and may have convulsions. Since it is unlikely anyone will have a thermometer handy to take the person’s temperature, watch for changes in behaviour (called mental status changes). This could indicate the early phases of heatstroke.
During endurance competitions, Emergency Medical Services are usually nearby, so the chance of suffering permanent damage is low; however, preventing the problem is always easier than trying to fix it, especially when it comes to one’s health.
Enjoy your competition. Just keep in mind some common-sense sun precautions to avoid turning a great day into a really miserable memory.

For additional information, visit www.dermatology.ca/outdoorworkers/index.html, which includes describes sun safety for outdoor workers and sun safety in general. 

About the Author

Joe Knight is a physician assistant and medical writer in Chowchilla, California.
 

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