Oct 23

Heatstroke: Some Explanations

by Kaitlyn Schaeffer

Heatstroke, or sunstroke, is the most serious heat-related disorder. Heatstroke is characterized by an internal body temperature of at least 104 degrees Fahrenheit. When an individual first begins to overheat, he or she can develop heat cramps. Failure to cool down leads to heat exhaustion, where one may experience nausea, extreme sweating, and faintness. If body temperature continues to rise, heatstroke occurs. It is important to seek immediate medical attention at this point; untreated heatstroke can result in permanent damage to the brain, kidneys, heart, and muscles, and can lead to death.

There are two types of heatstroke: exertional and non-exertional. Non-exertional heatstroke is generally caused by prolonged exposure to a hot environment that leads to a rise in body temperature, with or without physical activity. Exertional heatstroke is brought on by strenuous physical activity in a hot environment; those not accustomed to high temperatures are especially at risk.

Heatstroke and Seniors

One factor that increases an individual’s risk of heatstroke is old age. However, the aging process in and of itself is not responsible for heightened risk.

“The age card gets played way too much,” sighed Dr. Brent Ruby, director of the Center for Work Physiology and Exercise Metabolism at the University of Montana. Age is “not the primary driver” that increases one’s risk of heatstroke; “fitness level is a huge driver,” Ruby explained. “The more aerobically capable a person is, the more he or she is able to deal with heat stress.”

Unfortunately, Ruby noted, “as people age, they choose to be less active,” and inactivity leads to irregularities in ability to tolerate heat. “This means that even small amounts of work or exercise can lead to significant amounts of heat stress” Ruby cautioned.

Heat Stroke Prevention

Non-exertional Heatstroke

Non-exertional heatstroke comes on gradually as the result of being in a very hot environment for too long and not having enough fluid; these two factors combine to slowly but steadily increase the body’s core temperature. “For an older population that’s not very active, the non-exertional heat related illness creeps on sooner,” said Ruby. Seniors can combat increased risk for non-exertional heatstroke by working to increase their aerobic capacity, and making sure they stay hydrated and have cool, possibly air-conditioned places to rest.

Exertional Heatstroke

Exertional heatstroke occurs when an individual becomes overheated while performing physical activity in a hot environment. “When the body is active, it is producing heat,” Ruby explained. “You have to be able to offload this heat into the environment.” If an individual has difficulty offloading this heat, then the core temperature begins to rise and other heat-related symptoms begin to manifest. Active seniors need to pay attention to the intensity of their activities; different types of activity require different amounts of exertion – gardening may not require as much effort as going for a brisk walk.

While properly hydrating is essential for preventing exertional heat stroke, “frequent breaks are the most important asset,” Ruby emphasized. “Most people say that hydration is key, and it’s not! You can drink enough water and still not be fully protected if you’re working too hard for your fitness level in the environment that you’re in.”

Risk Factors

Certain factors put you at increased risk of heatstroke:

  • Some health conditions
  • Genetics
  • Lack of Air Conditioning
  • Certain medications
  • Abrupt exposure to hot weather
  • Old age

Heatstroke Symptoms

  • High body temperature
  • Headache
  • Nausea and vomiting
  • Confusion
  • Flushed skin
  • Racing heart rate
  • Rapid breathing
  • Unconsciousness
  • Muscle cramps or weakness

What to do when you think someone may have heatstroke

  • Seek immediate medical help by calling 911
  • Take steps to cool the person down:
  • Remove excess clothing
  • Move the person to a cooler area
  • Put ice packs or cool wet towels on the person’s neck, head, groin, and armpits


Dr. Brent Ruby, Ph.D., FACSM is director of the Montana Center for Work Physiology and Exercise Metabolism (Montana WPEM) at the University of Montana and a fellow of the American College of Sports Medicine (ACSM).

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