Things to Know: Heat Illness

It’s that time of the year when temperatures are rising! As temperatures begin to rise and our activity continues, it’s essential to be able to prevent, recognize, and treat exertional heat illnesses. Taking the proper precautions when it comes these heat-related illnesses are crucial for your overall safety.

Common Exertional Heat Illnesses
  • Exercise-Associated Muscle Cramps: These types of cramps can technically happen in multiple environments (cold, warm, hot, etc.).1,2 Typically, the cause of these cramps is associated with dehydration, electrolyte imbalances, fatigue, and/or altered neuromuscular control.1,2 Common signs and symptoms that are associated are muscle twinges, stiffness, tremors, or contractures.1
  • Heat Syncope: Heat syncope is also known as orthostatic dizziness and typically occurs in those who are not acclimated to the heat.1 In addition to this, dehydration, venous pooling of blood, reduced cardiac filling, or low blood pressure can cause this condition.1 Common signs and symptoms include fainting, dizziness, tunnel vision, pale or sweaty skin, and a decreased pulse rate.1
  • Heat Exhaustion: This condition typically occurs in hot and/or humid environments and affects those who are not acclimated to the heat and/or dehydration.1,2 It presents due to elevated core body temperature and is frequently associated with a high rate of volume of skin blood flow, heavy sweating, and dehydration.1 Weakness, dizziness, nausea, and headache are common sights and symptoms.1,2
  • Exertional Heat Stroke: This is the most severe heat illness that has been described as neuropsychiatric impairment and a high core body temperature.1,2 This condition can progress to a systemic inflammatory response and multi-organ failure unless it’s quickly and accurately recognized and treated.1 The risks of morbidity and mortality increases the longer an individual’s body temperature remains elevated above the critical threshold ( > 104oF).1,2 Common signs and symptoms include disorientation, irritability, unusual behavior, loss of consciousness, dehydration, hypotension, and hyperventilation.1
Prevention Strategies
  • Acclimatization to the heat should occur gradually over 7 to 14 days.1-3 This involves progressively increasing the duration and intensity of the activity and phasing in additional equipment that may be worn during the activity.1 Heat acclimatization has been considered one of the most important ways to protect the health of athletes while also improving their performance in hot conditions.3
  • Clothing worn during exercise should not restrict sweat evaporation. It’s important to note, that sunburn can limit thermoregulation in the affected area of the skin, therefore runners should be cautious of lengthy/repeated unprotected exposure to the sun.2
  • Do not participate in activity if you are currently sick with a viral infection or other illness.
  • Maintain proper hydration and replace fluids appropriately.1,2 The aims of fluid replacement are to prevent a body mass loss of more than 2%.1
  • Proper nutrition intake before, during, and after exercise.1,2
  • Get at least 7 hours of sleep per night.1
  • Take appropriate rest breaks to match environmental conditions and intensity of exercise and be prepared with cooling strategies (cold towels, cold packs, etc.).1,2
  • Be aware of any supplements or other substances that have a dehydrating effect, increase metabolism, or affect body temperature and thermoregulation.1

Being aware of heat related illnesses is important for everyone, especially those who exercise outside for long periods of time. The prevention strategies mentioned above play a key role in our health and safety. In addition to this, recognizing the signs and symptoms that are associated with heat-related illnesses can quite literally save your life!


1. Casa DJ, DeMartini JK, Bergeron MF, et al. National Athletic Trainers’ Association Position Statement: Exertional Heat Illnesses. Journal of Athletic Training (Allen Press). 2015;50(9):986-1000.

2. Bergeron MF. Heat Stress and Thermal Strain Challenges in Running. Journal of Orthopaedic & Sports Physical Therapy. 2014;44(10):831-838.

3. Bouscaren N, Faricier R, Millet GY, Racinais S, Adams WM. Heat Acclimatization, Cooling Strategies, and Hydration during an Ultra-Trail in Warm and Humid Conditions. Nutrients. 2021;13(4):1085.

Michelle Singleton
Michelle Singleton

Michelle has a diverse background in the exercise and sport science world. She is currently finishing her PhD focusing on Human and Sport Performance, with additional backgrounds in athletic training and nutrition. In addition to this, she is a certified and licensed athletic trainer, personal trainer, and educator. She utilizes her extensive education and clinical experience in athletic training, nutrition, and exercise science to help guide and educate others.

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