Ever feel a bit woozy after you crossed that finish line of the marathon? Like you were about to fall over and collapse on the ground? This is a common medical condition called orthostatic hypotension. When you have orthostatic hypotension, you will feel very faint and dizzy upon standing, caused by low blood pressure. According to a recent study at the University of Otago in Dunedin, New Zealand, researchers found that this hypotension along with reduced baroreflex control may cause the brain to have decreased blood flow—and lower levels of oxygen delivered to the tissue. Lower levels of oxygen to the brain tissue usually contribute to collapse after a prolonged duration of exercise, such as a marathon. In this particular study, seven athletes were physiologically monitored before and after the marathon event, within four hours. At a 15 degree Celsius temperature, they all were able to finish the marathon in an average of 261 minutes. They were again monitored 48 hours after the race. Data on the subjects’ middle cerebral artery blood velocity, blood pressure, heart rate, and cardiac output were measured before and while they were asked to stand for six minutes. Following the marathon, it was discovered that the athletes’ blood pressures lowered even though their heart rate, cardiac output, and sympathetic control all increased during standing and supine rest. Cerebral autoregulation remained unchanged post-marathon. Why is all of this important? Blood flow to the brain must be maintained and controlled within very narrow limits because it has the highest requirement for oxygen delivery to its tissues. Without proper blood flow and thus enough oxygen, you could very easily lose consciousness as well as mental capacity. How can this be prevented? KEEP MOVING. Be sure to have immediate access to proper electrolytes and hydration. Eat something. Doing so may help raise your blood pressure a little bit. Even though it might be the last thing you want to do after being on your feet for so long, moving around will prevent much worse consequences than some slight muscle fatigue the week after you run your race. Keep that brain of yours happy and healthy! -------------------------------------------------------------------------------------------------- - Murrell, Carissa, Luke Wilson, James D. Cotter, Samuel Lucas, Shigehiko Ogoh, Keith George, and Philip N. Ainslie. “Alterations in autonomic function and cerebral hemodynamics to orthostatic challenge following a mountain marathon.” Journal of Applied Physiology. 103: 88-96, 2007. 20 March 2007. - Orthostatic Hypotension. Dizziness-and-Balance.com. January 5, 2008. http://www.dizziness-and-balance.com/disorders/medical/orthostatic.html. 9 January 2008. *Photo from http://asymptotia.com/wp-images/2007/08/homer-simpson-wallpaper-brain-1024.jpg