COMMENTARY

Preparing for a Hotter Globe: A Sports Physician's Perspective

Bert R. Mandelbaum, MD, DHL (Hon)

Disclosures

October 04, 2018

Over the summer, I went on an expedition into the Canadian Arctic, as close to the North Pole as 79° latitude. I wanted to get a sense of one of the world's great wilderness areas and the majesty of polar bears, narwhals, and beluga whales, but the trip proved bitter sweet. While I saw spectacular beauty, I also witnessed the indirect and direct consequences of the Greenland ice cap breakup. Our boat even had to change its itinerary because of a shifting ice floe.

As a species, human beings are headed on a dangerous course, with climate change threatening our very lives on this planet. As citizens, we must do everything we can to change this direction regardless of cause. And as sports physicians, we must react to the effects on our patients: more mosquitoes bearing more infectious diseases, more storms and fires, and, especially, more hyperthermia.

Around the world this past summer, record temperatures kept cropping up. Japan hit its highest temperature ever recorded.[1] On the other side of the globe, England had its hottest summer ever.[2] Even into September, heat waves swept such diverse places as Denver,[3] Miami,[4] and St. Louis.[5]

The heat is already killing athletes. On May 29, 19-year-old University of Maryland football player Jordan McNair collapsed from heatstroke during a practice in College Park, dying about 2 weeks later.[6]

The team ran 110-yard sprints in 80° F weather, according to ESPN.[7] McNair's body temperature reportedly reached 106° F by the time he got to the emergency room, and the university is accused of not adequately cooling McNair to prevent the symptoms. The sports network reported that coaches at the school belittled athletes who could not complete grueling workouts; head coach DJ Durkin was put on administrative leave along with athletic trainer Wes Robinson, and strength and conditioning coach Rick Court resigned.[8] Ours is not to find fault but to learn from this very sad outcome.

The incident recalls the death of Korey Stringer of the Minnesota Vikings under similar circumstances in 2001, which inspired the creation of the Korey Stringer Institute to raise awareness of hyperthermia and related conditions. Unfortunately, many stakeholders in sports seem to need the type of publicity generated by a horrific incident to be motivated to be more vigilant. I've seen a similar cycle in anterior cruciate ligament injuries: a cluster of incidents inspires efforts at prevention, but these trail off until another cluster occurs.

In this light, sports medicine specialists must be sure they know the state of the art for preventing and treating hyperthermia. That begins with taking the climate into consideration. Athletes should train and compete under similar but more extreme conditions. The human body possesses marvelous capacities for adaptation, and just as athletes who will compete at high altitude should train at a slightly higher altitude, so should they train at a slightly more extreme temperature. For example, to prepare for Ironman in October in Hawaii, you have to find an even hotter, more humid environment in which to train. Acclimatization should take place gradually over at least 10-14 days with a base training established over months.

Second, sports physicians must keep an eye on the weather for a specific event. That includes not just ambient temperature but also relative humidity, wind, and solar radiation (direct sunlight). WetBulb Globe Temperature (WBGT) devices that combine these measurements are easily available, and the American College of Sports Medicine (ACSM) has developed guidelines for applying them to exercise.[9] For the 2016 World Cup, ACSM developed guidelines for soccer.[9]

Such guidelines can help athletes and coaches determine when to schedule practices and competitions. For example, in equatorial Fortaleza, Brazil, humidity often reaches 90%. But if you delay practices and games until after 2 PM, you can at least avoid direct radiant heat. Often, the optimal conditions come after 4 PM. Even casual runners are well advised to run in the morning or evening on extremely hot days.

Third, sports physicians have to make sure athletes get adequate hydration and nutrition. They should drink until their urine turns as clear as they can make it. But they shouldn't just drink water; electrolytes are essential to avoid dilutional hyponatremia.

More Tips to Combat Hyperthermia

This is not a new concept. The Khoisan Bushmen rehydrate during long hunts in the Kalahari Desert by drinking hypertonic blood, as they apparently have for thousands of years. These days, most athletes prefer sports drinks. Back in the 1980s, a friend and I unsuccessfully pitched such a drink to the 7 Up board of directors—who said there wouldn't be a market. A few years later, Gatorade really took off. Many sports drinks contain too much sugar, though, and in most circumstances, I recommend the low-sugar or sugar-free versions on the market now. It's also possible to get electrolytes with your water by taking "salt pills," taking specialized electrolyte packets or just salting your food and eating a banana.

We've learned that different sports require different and scalable approaches to hydration. Long-distance cyclists, for example, have to more fully load their livers with glycogen before cycling long distances. And that process starts 3 hours before the event; what you need at 10 AM is what you should drink at 7 AM. In fact, endurance athletes can load up with carbohydrates in the 24 hours before the event. This isn't just a matter of consuming enough calories to provide fuel; glycogen is essential to controlling body temperature.[10]

While excessive carbohydrate consumption has become a concern because it can elevate the risk for chronic diseases such as obesity and diabetes, athletes competing at high intensity or duration in high temperatures really need that glycogen stored in liver and muscle.

Fourth, sports physicians must ensure that coaches, athletes, and trainers keep equipment on hand to treat hyperthermia and teach them to watch for its signs. In addition to a WBGT device, this includes a rectal thermometer and lubricating gel, a tub or kiddy pool, a cooler stocked with ice, a water source, towels, and a shade tent.

Symptoms typically start with weakness and fatigue and progress to confusion and disorientation. Athletes with heat exhaustion may appear pale and sweat heavily. The loss of electrolytes may lead to spasms, and cramps may become so severe that the athlete can no longer perform. In the next stage, the athlete may faint.

When these symptoms appear, it's essential to cool athletes down, first by moving them to a cooler place, such as shade. Remove excess clothing, elevate their legs, and provide fans, ice towels or ice bags, and oral fluids. Give athletes with cramps a solution containing electrolytes, and stretch or massage the cramped muscle. Athletes with heat exhaustion should not return to the activity for 24 to 48 hours.

Heat stroke is a potentially fatal condition. In addition to the symptoms of heat exhaustion, symptoms can include headache, nausea, vomiting, or diarrhea. It is characterized by a rectal temperature greater than 104° F. (Alternative temperature measurements are not reliable.) Athletes with heat stroke should be immersed as quickly as possible in a tub or tank with ice and water at a temperature of about 35-58° F. Stir the water and add ice throughout the cooling process. Maintain the ABCs: airway, breathing, and circulation.

Heat stroke is a medical emergency, and emergency responders should be contacted immediately by dialing 911. Cease cooling when the rectal temperature reaches 101-102° F.

These comprehensive measures should help sports physicians prepare for the rising heat of the coming years.

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