Heat Syncope is also known as orthostatic dizziness. This refers to a fainting episode that someone can experience in high environmental temperatures, usually during the initial days of heat exposure. Heat syncope occurs when an individual in a hot environment does not have adequate blood flow to the brain, causing the person to lose conciousness. This commonly occurs when someone is standing for long periods of time without movement or sudden rising from a sitting or lying position in the heat.
How do you prevent heat syncope?
Heat syncope often occurs in individuals that are unacclimatized to the heat (the body is not used to increased environmental temperatures) therefore, individuals should adapt to exercise in the heat gradually acclimatize over 10-14 days by progressively increasing duration and intensity of work.
Heat syncope may also be due to dehydration, which limits total blood volume, and predisposes individuals to syncope. All exercising individuals should be appropriately hydrated prior to exercise and maintain hydration throughout practice to ensure a large blood volume. By drinking adequate liquids, individuals decrease their chance of succombing to exertional heat illnesses.
Additional ways to prevent heat syncope include avoiding alcohol, avoiding exposure to warm environments, wear clothing that blocks the sun's rays, and exercising during cooler times of the day.
What puts an individual at risk for heat syncope?
The common factor between occurrences of heat syncope is a temporary lack of adequate blood supply to the brain. Standing for long periods of time without muscular contractions allows blood to pool at the feet and not return centrally to the heart or to the brain. Additionally, wearing heavy equipment (such as football pads or firefighter bunker gear) and a uniform increases sweating, resulting in dehydration.
Look for these symptoms in athletes when heat syncope is suspected:
Individuals experiencing heat syncope typically have normal exercising body temperatures. They could present with the following:
|Dizziness (vertigo) or lightheadedness||Weakness|
|Loss of consciousness||Tunnel vision|
|Pale or sweaty skin||Decreased or weak pulse|
How do you treat an individual with heat syncope?
Typically individuals who experience heat syncope will recover relatively quickly, within 10-15 minutes with minimal treatment and monitoring
- Move the person to shaded/cool area to decrease body temperature
- Sit or lie down as soon as the patient begins to feel symptoms
- Monitor vital signs to ensure the person does not also acquire another medical condition
- Elevate legs to promote blood returning to the heart
- Rehydrate with water or a sports beverage
When can the individual return to activity?
An athlete may return to play once his/her symptoms have resolved and any other medical conditions have been ruled out. The athlete should to rehydrate as necessary and seek medical clearance before returning to practice.
Where can I get more information?
Please check out our general guidelines for heat illnesses and the heat cramps and exertional heat stroke pages for further information.
- Armstrong LE. Exertional Heat Illnesses. Human Kinetics; 2003.
- Armstrong LE, Casa DJ, Millard-Stafford M, Moran DS, Pyne SW, Roberts WO. American College of Sports Medicine position stand: exertional heat illness during training and competition. Med Sci Sports Exerc. 2007;39:556–572.
- Binkley HM, Beckett J, Casa DJ, Kleiner DM, Plummer PE. National Athletic Trainers’ Association position statement: exertional heat illnesses. J Athl Train. 2002;37:329–343.