Exertion headaches differ from other types of headaches in that physical activity triggers them.
In sports medicine and research literature, an “exertion headache” is recognized as a distinct condition, says Colin Tomes, PhD, PT, an assistant clinical professor of health sciences at Moravian University in Bethlehem, Pennsylvania. “This term is crucial because headaches may occur during physical exertion that stem from another cause, which may be of concern.”
That said, the physical event that triggers an exertion headache can vary. It could be anything from running to yard work to sex, says Klee Bethel, MD, an anesthesiologist pain interventionist at the Neil Riordan Center for Regenerative Medicine in Tempe, Arizona.
It’s not clear why exertion headaches occur in some people and under some circumstances but not others. One theory is that strenuous exercise dilates (widens) blood vessels in the skull. When this reaches a certain threshold, throbbing and pain can result.
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Regardless of the exact mechanism, however, certain factors increase the likelihood of an exertion headache. They include:
Exercise
An exertion headache is often a result of overexertion during exercise. The combination of dehydration (more on this shortly), pressure inside the skull, and muscle tension that results from intense or prolonged exercise can create a perfect storm for head pain, Dr. Chen says. The high-impact nature of running makes it particularly likely to cause headaches, he adds.
Dehydration
A lack of fluids can be a significant contributor to exertion headaches, especially when exercising outdoors or in high temperatures. “Low fluid levels thicken blood and stress blood vessels, reducing nutrient and oxygen delivery and potentially triggering headaches,” says Dr. Tomes.
Too Much Sun
Sun overexposure is a risk factor for heat exhaustion, which often shows up with a headache.
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Exercising in sunny conditions can make you more prone to heavy sweating, causing dehydration that can trigger head pain.
Tomes recommends gradually increasing your outdoor exercise to acclimate yourself to the heat slowly.
Low Blood Sugar
One benefit of exercise is that it can help lower blood sugar for up to 24 hours.
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For most people, that’s a good thing. However, for people with existing blood sugar problems, low blood sugar could cause a headache, says Dr. Bethel.One study, for example, found that some types of migraine, which often causes head pain, may happen when the brain is unable to use glucose (sugar) effectively.
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If you have a tendency toward low blood sugar, you might have a higher risk of exertion headaches.
Poor Exercise Form
Headaches after running, cycling, or strength training could signal an issue with your body mechanics. When your exercise technique isn’t on point, it places excess stress on your muscles and joints, causing tension.
“Muscle tension, particularly in the neck and shoulders from poor posture or overexertion, can compress nerves and blood vessels, contributing to headache onset during physical activity,” says Chen.
Underlying Health Conditions
Not all exertion headaches are as simple as they seem. “Some headaches are secondary to health issues, such as blood vessel problems, heart disease, and structural brain lesions,” says Tomes.
For example, reduced blood flow to the brain caused by blood vessel or heart issues could predispose you to headaches. Brain lesions from neurological conditions like multiple sclerosis, meanwhile, are known to cause head pain even without physical exertion.
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Consult your primary care provider if your symptoms are new or you suspect your exercise headaches have an underlying cause.
