Oh my aching head! Many individuals who exercise have exertional headaches. Recent studies have delineated a clear-cut exertionial headache syndrome: Straining or a Valsalva-type maneuver precipitates the acute onset of severe throbbing pain, usually occipital, for a few seconds to a few minutes. The headache then settles to a dull ache lasting 4 to 6 hours. In subsequent weeks to months, the headache recurs with exertion. The patient has no history of migraine and a normal neurologic exam. Exertional headaches are thought to be vascular, but this is unproven. According to one theory, exertional headache occurs because exertion increases cerebral arterial pressure, causing the pain-sensitive venous sinuses at the base of the brain to dilate. Studies of weight lifters demonstrate that, with maximal lifts, systolic blood pressure may reach levels above 400 mm Hg and diastolic pressures above 300 mm Hg. The throbbing, migrainous nature of these headaches, together with the finding that intravenous dihydroergotamine mesylate can relieve them, supports the supposition that these headaches have a vascular basis.