Tips for Exercising in Summer Heat Safely

Headlines about otherwise healthy people — including teens and young adults — who die while exercising outdoors in summer heat have sadly almost become background noise. As the effects of climate change are increasingly making their mark, with heat waves becoming more common, they will only grow more common. Don't become a tragic statistic. Avoid heat exhaustion, and its most severe form; heatstroke. Exercise responsibly in extreme summer heat by following these vital tips. 

Essential Information for Avoiding Heatstroke

While people who live in dependably hot summer climates like Arizona, Texas, and Saudi Arabia build up resistance to heat, people who try to maintain their outdoor exercise routines during unusually hot heat spells are at special risk of heat stroke. Not being used to extreme temperatures, they need to take additional care.
 

What Is Heatstroke?

Heat-related illnesses exhibit a continuum of symptoms ranging from prickly heat, which is the irritation of the skin caused by heat, to heatstroke, in which body temperatures in excess of 106° F (42° C) literally coagulate the proteins of the brain. Warning signs that heatstroke may be on the way include twitchy muscles (tetany), loss of consciousness (syncope), and extreme fatigue.

Exertional heatstroke is most common in teens and young adults. This form of heatstroke occurs during heavy exercise outdoors in extreme heat. Exertional heatstroke is most likely to occur in areas that get regular hot weather, when young athletes underestimate their need for fluids.

Classic non-exertional heatstroke is most common in infants and the elderly. This form of the heatstroke is unrelated to exercise. It occurs when perspiration simply cannot keep up with the need to cool the body. This type of heatstroke can occur in babies because they do not have enough skin surface area to cool themselves. It can occur in elderly people because their peripheral nervous systems have been damaged and no longer trigger a sweating response, or because they take medications that prevent sweating. Non-exertional heatstroke usually occurs during heatwaves that bring unusual heat and humidity.
 

How Common Is Heatstroke?

In the United States, heatstroke is rare except among athletes in the hot summer states. In other parts of the country, however, on average 334 people a year die of heatstroke, less than half of them elderly persons suffering non-exertional heatstroke. In Russia in 2010, over 40,000 people died of heatstroke during their highest ever recorded summer temperatures.

In the United States, heatstroke is the second leading killer of teenaged athletes, most commonly striking teens who had recently arrived at hot-summer location from a cool-summer location. Untreated, 80% of cases of heatstroke cases sadly result in death.
 

What Can You Do About Heatstroke?

The most important thing teammates and observers can do when they see someone showing signs of heat exhaustion or heatstroke is to treat symptoms as if they were heatstroke. Heatstroke usually involves a body temperature of over 105° F (41° C) and anhidrosis, the inability to sweat, but brain damage can occur at lower temperatures and even when there is some ability to sweat. Muscle cramps, abdominal cramps, shortness of breath, dizziness, weakness, and "brain fog" may indicate heat exhaustion or they may indicate heatstroke. To be on the safe side, treat them as if they were heatstroke.

Survival from heatstroke depends on getting the victim to medical treatment during the first hour. Place the heatstroke victim or potential heatstroke victim in a position that keeps airways open. Remove restrictive clothing and apply cool cloths. Do not attempt to pack the victim in ice — it's possible to overshoot the desired body temperature and cause hypothermia. Getting medical treatment as quickly as possible saves lives. But there are also measures you can take to avoid heatstroke and heat exhaustion from ever setting in.
 

Tools for Safe Exercise in Summer Heat Aren't Just What Makes You Feel Cooler

The Journal of Athletic Training reports a study of ice collars to be worn around the neck as a tool for preventing heat exhaustion and heat stroke.

Exercise physiologists at Roehampton University in London heated an exercise room to what they called a "stifling" 31°C (87° F). (Unpleasant temperatures are relative. In Texas, where I live, 87° F on a summer day might be a record low.) They recruited volunteers to do a timed run on treadmills with and without an ice-filled neck collar. Not surprisingly, the volunteers could cover a significantly larger distance without any discomfort if they wore the ice pack.

Very surprisingly, the researchers found that the ice pack did not actually lower core body temperature. It only lowered the temperature of the skin on the neck. The ice pack collar did not lower temperature in the heart, lungs, or muscles of the legs thought to be more important to running.

In a second round of testing, the researchers asked a different group of volunteers to exercise in the hot room to the point of exhaustion. The scientists found that volunteers who wore the ice collars could exercise considerably longer, but that when they stopped, their core temperatures were considerably higher. Wearing an ice pack was associated with higher body temperature.

A higher body temperature, of course, is associated with greater risk of heat exhaustion and heat stroke, so what was going on?

The Roehampton University researchers concluded that wearing the ice collar masked the symptoms of heat exhaustion. (None of the volunteers was allowed to experience heatstroke, although some of the volunteers' rectal temperatures exceeded 40° C.) The volunteers' body temperatures went higher and higher, but they did not feel uncomfortable because the brain only registered the temperature of the skin at the neck.

Christopher James Tyler, a lecturer in sport and exercise physiology at Roehampton University and the lead author of the Journal of Athletic Training study, explained that ordinarily when an exerciser's core temperature reaches 40° C (104° F), the brain stops sending signals to the muscles that allow exercise and heating stops before heatstroke begins. When the neck is cooled, however, the brain is cooled and it does not stop exercise before heatstroke can occur.

So are ice collars safe for athletes? What about the older method of freezing a damp towel to drape over the shoulders or a wet bandana to put on the head before going out in the heat?

These cooling methods may give an athlete a competitive edge (assuming they do not cause a debilitating "brain freeze" headache when the cold cloth is applied to the skin), but at the cost of greater risk of heatstroke. "All-over" cooling methods such as overhead misters (popular in Arizona) and simple splash of water over the chest, arms, and legs offer much better protection against heat exhaustion and heatstroke. It is equally important to drink water before feeling thirsty, to maintain electrolytes, and to recognize that greater athletic performance despite heat is usually a sign the brain is not picking up the body's signals to seek cooling.

For comprehensive information about preventing exertional heatstroke, visit the Korey Stringer Institute pages at the University of Connecticut website.