Brain Aneurysms and Strenuous Activity
Brain aneurysms develop silently and most do so as a result of wear and tear on the arteries throughout a person’s lifetime, though no clear etiology can usually be established. The precise pathophysiological mechanisms leading to brain aneurysm rupture are not completely understood. There is compelling data suggesting that moderate to heavy physical activity, such as weightlifting, may trigger aneurysm rupture and/or subarachnoid hemorrhage (SAH). During heavy weightlifting and other strenuous activity (even including breath-holding associated with bowel movements) associated with breath holding, a person typical engages in the Valsalva maneuver (forceful attempt of exhalation against a closed airway) which results in increased intrathoracic pressure. The increase in intrathoracic pressure and subsequently induced venous hypertension, in turn, increases the transmural pressure gradient across an aneurysm’s wall and can trigger an aneurysm rupture. Another mechanism of aneurysm rupture is the activation of the sympathetic nervous system during strenuous physical activity. The increase in heart rate and blood pressure in conjunction with the Valsalva maneuver during physical efforts are transduced to the cerebrovascular system which thereby increases aneurysm wall tension and the risk of rupture.
Weightlifting is known to induce supraphysiologic blood pressures and intense physical exertion and can increase the risk of aneurysm rupture by as much as 15-fold. Catastrophic brain injury such as stroke, cerebral hemorrhage, SAH, retinal hemorrhage, and retinal detachment have all been associated with such activities because of these physiological responses. Prospective studies of large populations have found that moderate to extreme physical exercise was associated with tripling the risk of aneurysm rupture in the subsequent 2 hours whereas light or no activity was not associated with any increased risk. Surveys of activities preceding aneurysmal SAH have shown that is common for patients to be engaged in at least moderate activity before these events.