Primary exercise headaches

The exact cause of primary exercise headaches is unknown. One theory is that strenuous exercise dilates blood vessels inside the skull.

Secondary exercise headaches

Secondary exercise headaches are caused by an underlying problem, such as:

• Bleeding in the area between the brain and the thin membranes that cover the brain (subarachnoid hemorrhage)
• Abnormalities in a blood vessel leading to or within the brain
• Cancerous or noncancerous tumors
• Obstruction of cerebrospinal fluid flow
• Sinus infection
• Structural abnormalities in the head, neck or spine