It was the 4th of July, and I was doing a 100-mile (and 100-degree) charity cycling event. About 40 miles into the ride, while stopped at a red light, I glanced at the watch of the young, athletic woman paused next to me. Though she was standing still, the heart rate monitor on her wrist was at 192—quite high.
First, I urged her to drink. She was out of water. I convinced her to take one of my unopened bottles of electrolyte drink, but she claimed to be too nauseous to drink. She also remarked she had a slight headache. Then, it was one red flag after another—signs of heat illness were present, yet this athlete insisted she was fine and would continue riding.
By this time, several other cyclists had joined us, and all were concerned. After declaring that we were all quitting if she didn’t address her symptoms, she agreed to pull to the side and sit in the shade. We iced her neck for more than 20 minutes before her heart rate began to come down!
So, I ask you: What if that light had been green? She would have continued on and this story would perhaps have an ending that involved an ambulance.
Such stubbornness is common in endurance athletes. We believe that by sheer will, we can ignore the red flags our body throws up and continue on. But when it comes to heatstroke, a “mind over matter approach” is unwise, as the mind is likely not firing on all cylinders. Why? Because during an episode of heatstroke, the brain reaches temperatures above 105 degrees Fahrenheit—it’s too hot to do the things it should do, like regulate body temperature and heart rate.
But this is more than just a tough day of training. It’s life-threatening, and it’s up to us to watch out for our fellow athletes. Just as “friends don’t let friends drive drunk,” friends also don’t let friends suffer heat illness. If you suspect one of your fellow triathletes is exhibiting signs of heatstroke, say something! You might just save a life.
What Should I Look For?
Early signs of thermoregulation issues include nausea, dizziness, headache, rapid heart rate, out of proportion fatigue or weakness, goosebumps or chills. These symptoms occur as the body temperature is rising and signal heatstroke is imminent, unless there is a change. When these red flags are present, stop activity immediately, move to a cool environment, elevate their feet, and drink electrolyte beverages.
More serious signs include confusion or disorientation. This altered mental or cognitive state is the key criterion of heatstroke, and a sign medical intervention is needed immediately. Additionally, watch for those who may be unconscious. If you see an athlete resting with their eyes closed after a race or hard workout, check on them. So long as the athlete is responsive and answering questions coherently, it’s likely they’re fine; if they struggle with simple questions, however, it’s time to take action.
Another tell-tale sign of heatstroke is the absence of sweat. Look at their skin to see whether they have ceased to sweat. Don’t let prior sweat remaining on the skin fool you.
Without intervention, this situation can lead to coma and death. If an athlete exhibits the signs of heatstroke, move the person out of the sun and cool the whole body ASAP by putting the body in an ice bath or soaking the clothing and fanning vigorously. At this critical stage, ice bags on small areas are not effective—cool the entire body. Call 911, and send a bystander to be conspicuous and route the ambulance driver in.
Maintain hydration: 80% of body temperature control during exercise is via evaporation of sweat. Volume of fluid needed with exercise depends on multiple factors including environment, body size, effects of frequent training in the heat, and magnitude of muscular heat creation with exercise. To offer an example, a 75 kg or 165 lb athlete training on a hot, humid day might sweat 2 liters (67.6 oz) per hour. That would be 11.3 oz every 10 minutes. Many bike bottles are 24 oz, so this athlete would need to drink one of them every 20 minutes. That’s three tall water bottles just for the first hour—and that is an underestimate because the kidneys continue to form urine. To restore fluid balance, multiply the volume above by 1.25-1.5. About the choice of beverage composition, the American College of Sports Medicine recommends beverages with 0.5-0.7 grams of sodium per liter consumed during exercise of greater than one hour duration. Adding potassium may enhance fluid retention in the intracellular space and reestablish potassium excretion that accompanies sodium retention by the kidneys.
Weigh yourself (dry) before and after exercise. For every pound lost, drink 16 oz x 1.25-1.5 of fluid.
Dress for the environment: The highest sweat rates are mid- and low-back and forehead, so understand that any sweat that drips off or stays on the skin contributes nothing to cooling. Expose high sweat rate areas so that the sweat will evaporate off the skin, cooling the skin. Clothing that fits loosely and is made of fabrics that promote wicking [the free movement of water vapor through the fabric] enhances cooling. Wear as little as possible, except wear a hat in abundant sunshine.
Train (safely) in the heat: Don’t expect to train in air conditioning and be prepared to race outdoors in the heat. Allow for acclimatization. Increase heat tolerance gradually across 10-14 days. Athletes that train according to a heart rate range should stay in that range when in higher temperatures even though the speed at which they reach that heart rate will be lower. Be accepting of slower speeds and shorter distances. As you condition, training effects such as increased blood plasma volume will occur and speed will improve.
Take rest breaks in the shade: Take more (and longer) breaks as needed to keep heat stress symptoms at bay. Remember to drink frequently as noted above. Training effects include sweating sooner (cooling sooner), and sweating a more dilute (less salty) sweat thus keeping electrolytes in the body.
Make a deal with yourself before going out, especially to race: Heatstroke affects anyone and everyone, regardless of fitness level. Even the toughest triathletes have been brought to their knees because they didn’t know when to say when. Make a deal with yourself that if you feel symptoms of heat exhaustion coming on, you will take the appropriate actions as described above.
Greg McElveen, MS, MBA, CSCS, is the director of the Sports Performance, Lifelong Athlete and EverStrong programs for the Duke Sports Sciences Institute at Duke University Medical Center.