The LaSalle Bank Chicago Marathon was run Sunday in the hottest temperature — 88 — ever recorded during the event, but participants would have been better off running in the heat of August, experts said.
At least then, when almost every day is hot, more runners would have been acclimated to the weather, said Kathy Weber, an attending physician in sports medicine at Rush University Medical Center. Acclimating can take 10 to 15 days, so the unseasonably hot day caught runners off guard, she said.
“I’m sure there were people pushing the envelope,” Weber said. “You can be a very experienced runner or a first-time runner. If the conditions aren’t right for you that day, it might just be a bad day.”
At least 312 runners were taken to medical tents and hospitals, Chicago Fire Department spokesman Larry Langford said. Most cases involved heat illnesses.
If the athletes had been training in hot weather, their bodies would have been better able to dissipate the heat by sweating, Weber said. Besides the high temperature, the humidity further diminishes the body’s ability to cool itself.
When a person sweats, part of that fluid comes from blood plasma, said Anne Thilges, an exercise physiologist at San Francisco State University who completed 10 Ironman Triathlons. As a result, that person’s blood pressure drops, she said.
“To counteract, the body will increase the heart rate in order to maintain cardiac output,” she said. “But this also means the body is working harder. Extremely hot weather can increase this effect, as can muscle fatigue. Thus, running a long distance in heat hits the body with a sort of double whammy.”
As athletes work harder, blood that should be sent to the skin’s surface to cool through sweating is instead used to keep the muscles working, said Mark Gorelick, assistant professor in San Francisco State’s Department of Kinesiology. This leads the body to sacrifice its ability to reduce its core temperature.
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There are three major heat illnesses: heat cramps, heat exhaustion and heatstroke. Dehydration is the main culprit.
Heat cramps cause sharp, stabbing pain and muscle aches, said Terry Vanden Hoek, associate professor in emergency medicine at the University of Chicago.
Heat exhaustion is characterized by dizziness, fatigue, nausea, vomiting, headache and signs of confusion. When the body reaches the most severe level, heatstroke, its cooling mechanism has shut down, Vanden Hoek said. The body temperature reaches 103 or 104 degrees, which can cause seizures, loss of consciousness, coma, cardiac arrest and death.
“It’s a normal thing to want to push yourself and do well, but it’s not worth risking your health over,” he said.
As a runner’s level of heat injury increases, the athlete becomes more and more disoriented, said Noel D. Nequin, a cardiologist with Swedish Covenant Hospital.
“You can’t reason with yourself,” he said, so that makes it harder to decide whether to stop or get more fluids.
“It’s dangerous when it’s that warm if you’re pushing yourself without all the precautions,” said ultrarunner Dean Karnazes. He is a six-time veteran and former champion of the Badwater Ultramarathon, a 135-mile race across Death Valley held in July, when the temperature soars to about 125 degrees. “When we do Badwater, we prepare for it.”
And even then, the heat can be deadly. Karnazes blacked out because of dehydration the first time he ran the race.
Karnazes suspected the Chicago runners might have had problems because they simply didn’t, or couldn’t, adjust to the conditions.
It gets dangerous, he said, “when the temperature gets that hot and people stay on the same pace and don’t scale back. They try to stay on the same programs as if it’s a normal Chicago year instead of going out slower.”
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When heat becomes life-threatening
Increased physical activity and prolonged exposure to the sun during hot, humid weather can bring on heatstroke, a dangerous condition in which the budy is unable to cool itself. Heat exhaustion is a condition in which the body becomes dehydrated.
Recognizing and treating heat-induced illnesses
HOW IT STARTS
HEAT EXHAUSTION: Insufficient water and salt intake are the primary causes. Faintness, dizziness and fatigue usually are the first signs of heat exhaustion.
HEATSTROKE: Heat exhaustion, if untreated, can develop into heatstroke as heat builds up in the body. (People who aren?t treated quickly can die.)
SKIN
HEAT EXHAUSTION: Usually cold and clammy, with heavy sweating.
HEATSTROKE: Hot, dry and red. Perspiration usually stops completely.
PULSE
HEAT EXHAUSTION: Rapid and weak.
HEATSTROKE: Rapid and strong.
BODY TEMPERATURE
HEAT EXHAUSTION: Usually low or normal.
HEATSTROKE: Above 103 degrees. At 107 degrees, usually is fatal.
OTHER SYMPTOMS
HEAT EXHAUSTION: Thirst, giddiness, weakness and lack of coordination.
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HEATSTROKE: Fainting or staggering, confusion or delirium.
TREATMENT
HEAT EXHAUSTION: Lie down in a cool, shady place; loosen clothing; sip water (unless nauseous); seek medical attention immediately if vomiting occurs.
HEATSTROKE: Seek medical attention immediately; move to a cool place; remove clothing; apply a wet sheet or immerse in cool water.
Sources: Centers for Disease Control and Prevention, American Medical Association Encyclopedia of Medicine, Complete Guide to Sports Injuries
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