Endurance runners have higher risk for heat stroke than heart condition


September 24, 2014

Topic: heat-related illnesses

Researchers discovered that long-distance runners are more likely to deal with heat-related illnesses while running in warm weather than cardiac events.

Researchers discovered that long-distance runners are more likely to deal with heat-related illnesses while running in warm weather than cardiac events. Their findings were published in the Journal of the American College of Cardiology.

The study authors found that heat stroke is 10 times more threatening for runners than any type of heart condition. They believe their findings may contribute to the ongoing debate for pre-participation EEG tests that help identify health risks for runners during a race. 

Cardiac events vs. heat stroke
For a long time, physicians have recognized that the two greatest risks for runners in a warm climate are dealing with a heart arrhythmia, which is caused by undetected heart disease, or having a heat stroke. However, the researchers found that cardiac events get more attention than heat-related illnesses. Yet, they should not.

Lately, endurance races over six miles are becoming more popular. So, the researchers decided to figure out how many life-threatening situations that occurred during races were related to heat stroke and how many were related to heart conditions. Any occurrence that required hospitalization in an intensive care unit and mechanical ventilation was considered a life-threatening event.

The study authors examined data of hospitalizations and life-threatening scenarios from 14 popular endurance races in Tel Aviv between March 2007 and November 2013. Approximately 137,580 runners were used in the study. Only two considerable cardiac events occurred during the time period, and neither was life-threatening. In comparison, the study authors found 21 cases of heat stroke, two of which were fatal and 12 of which posed life risks.

Israeli sports law requires all participants on teams to have an EEG exam before entering a race, but not individual runners. Individuals only had to submit a statement confirming they were in good health. Researchers asked 513 of the runners surveyed if they had undergone an EEG screening before the race. Only 35 percent had an EEG the previous year and 46 percent had one in the past five years. These results indicated that the small amount of cardiac events found were not because of proper screening methods. 

Lead study author Sami Viskin, M.D., stated that, though heat stroke poses a significant risk to runners, there are no standard methods to prevent it from happening. Viskin noted that physicians should educate runners before events.

"It's important that clinicians educate runners on the ways to minimize their risk of heat stroke, including allowing 10-14 days to adjust to a warm climate, discouraging running if a person is ill or was recently ill because a pre-existing fever impairs the body's ability to dissipate additional heat stress, and developing better methods of monitoring body core temperature during physical activity," Viskin said in a statement.

Prevention tips
There are a few general tips that endurance runners should consider before participating in a marathon or other long-distance event, according to the U.S. Centers for Disease Control and Prevention. Some of these tips include:

  • Wear lightweight and loose-fitted clothing that is light in color.
  • Drink two to four glasses of a cool beverage each hour. Sports drinks can help replenish the salt and minerals lost in sweat.
  • Put on sunscreen of SPF 15 or higher.
  • Wear wide-brimmed hats.

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