Ask a Doc: Heat Stroke

July 29, 2015
  •  98.6 degrees is considered the “normal” temperature for a human.

  • Heat Stroke may cause brain, kidney and muscle damage.

  • The hottest temperature recorded on Earth is 134 degrees.

Dear Doc:
I recently read an article about the dangers of exercising on hot days. What can I do to prevent “overheating” on my summer runs?

The human body is very good at trying to maintain a “normal” body temperature. When your body is too hot, the blood vessels in your skin dilate (expand) bringing the excess heat to the skin’s surface causing you to sweat. As the sweat evaporates, your body cools down. (Interestingly, dogs have limited sweat glands and need to rely on panting to cool down.) When your body is cold, the blood vessels constrict (narrow), and your body shivers which helps generate heat. The body is usually able to regulate its temperature in a narrow range to keep all of its organs functioning optimally.

The body temperature (temp) can be measured in many places including the mouth, ear, rectum, armpit or forehead (of course with a thorough cleaning or new probe between each measurement)! Traditionally, a “normal” temp is considered 98.6 degrees. This is an average of normal temperatures. Your specific “normal” temp may vary one degree or so to either side of 98.6. In fact, throughout the day your body temperature may rise by a degree depending on how active you have been. A woman’s temperature may fluctuate with her hormone cycle. Rectal or ear temps are higher than oral temps, while armpit temps will be lower than oral temps. In most adults, an oral temp above 100 degrees or a rectal / ear temp of 101 degrees is considered a fever.

The weather outside can clearly influence our body temperature. The highest recorded temp in Rochester was in July 1936, 102 degrees. The coldest was in February 1934, -22 degrees. Temps have warmed 1.53 degrees from 1880 to 2012. 2013 marked the 37th consecutive year of above average temperatures. The Earth and Moon are relatively the same distance from the sun, yet they have vastly different weather. On the moon, temps may reach 212 degrees during the day and may plunge to -279 degrees at night. On Earth, the hottest recorded temp was 134, recorded in Death Valley and the coldest was -128.6 noted in Antarctica. It is the Earth’s atmosphere (the moon does not have a significant atmosphere) that insulates the Earth and helps narrow the temperature gap from day to night. There is evidence that man’s use of fossil fuels and the resultant increase in CO2 added to the atmosphere has contributed to the rise in temperature on earth, the so called global warming.

Random fact: Experts say to maintain the best flavor quality; coffee should be served between 155 and 175 degrees.

Exercising in the heat can lead to significant fatigue and dehydration but the most serious consequence may be heatstroke. There are thousands of preventable heatstroke ER visits each year. Heatstroke develops when your body’s cooling adjustments cannot keep up with the heat being generated. You are considered to have heatstroke when your body reaches 104 degrees. When your body starts to overheat you may develop heat cramps. If your body does not cool down, heat exhaustion manifested by heavy sweating, nausea, and dizziness may develop. Heatstroke symptoms will develop if your body temp continues to rise. These symptoms may include vomiting, rapid breathing, rapid heart rate, confusion, headache, and further muscle cramps. If untreated, heat stroke may cause damage to your brain, heart, kidneys and muscles.

Those at risk for heat stroke include the very young and very old; their bodies don’t regulate temperature as well. In addition, those with chronic illness, Parkinson’s disease, uncontrolled diabetes, alcoholism, obesity, and those on certain medications may have an impaired ability to cool down in severe heat.

If you think heatstroke is developing, seek medical attention immediately. Take immediate action to cool your body. Remove excess clothing, seek shade, place ice packs or cool towels on the skin, and hydrate with cool liquids. Medical treatments may include intravenous hydration and the use of cooling blankets.

To prevent heat stroke: wear loose fitting, light colored clothing (which reflects the sun’s rays), drink plenty of fluid, limit the time spent exercising in the heat, and pay attention to the warning signs of overheating.

Stay hydrated and cool. Enjoy your summer runs and take satisfaction in the fact that by running instead of driving your car, you are doing your part to prevent further global warming and even more heat strokes!

Stay healthy and remember the quote by Sarah Condor, “Remember, the feeling you get from a good run is far better than the feeling you get from sitting around wishing you were running.”

Nagpaul_arunDr. Nagpaul is a medical doctor and is board-certified in Internal Medicine. He currently is the Medical Director at Newark-Wayne Community Hospital, DeMay Living Center and Wayne County Public Health. This column is meant to be educational and not intended to be used to make individual treatment decisions. Prior to starting or stopping any treatment, please confer with your own health care provider. To send questions, please email Dr. Nagpaul at and put “Ask a Doc” in the subject line.


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Rochester Regional Health is an integrated health services organization serving the people of Western New York, the Finger Lakes and beyond. The system includes 150 locations: five hospitals; more than 100 primary and specialty practices, rehabilitation centers and ambulatory campuses; innovative senior services, facilities and independent housing; a wide range of behavioral health services; and ACM Medical Laboratory, a global leader in patient and clinical trials. Rochester Regional Health, the region’s second-largest employer, was named one of “America’s Best Employers” by Forbes in 2015. Learn more at