As a sports medicine and family medicine doctor, and indeed in this blog, I tend to focus on exercise, musculoskeletal and metabolic rather than neurologic conditions. In part, this is because, most of the research surrounding exercise are in these three areas.  However, while blood flow to the brain is the most important task for the circulatory system, yet there is little research into the effects of exercise on perfusion to the brain.  I recently read an article in this month’s Exercise and Sport Sciences Reviews that starts to address this deficiency.  Hirofumi Tanaka from the University of Texas at Austin concludes that exercise actually helps brain blood flow both during and after exercise.

The traditional thought was that during exercise, blood supply is constant to the brain but  is shunted away from the rest of the body and pushed to the muscles. After all, you can’t have a functioning stomach if you have just been killed by that lion because you could not run away. Brains are thought to have an intrinsic auto-regulatory function that allows this constant blood supply to keep us conscious even while exercising. According to experts Shigehiko Ogoh, Ph.D. and Philip Ainsle, Ph.D., from Toyo University in Japan and the University of North Texas, blood flow actually increase during and after exercise.

Cerebral blood supply is a complicated maze with its own set of rules since it is such a critical organ. Autoregulation as well as external cues like the level of carbon dioxide in the blood, blood pressure and how much blood the heart pumps out are all implicated in determining the amount of blood that is reserved for the brain during exercise.

What is interesting to me is the implication for diseases caused in part by a lack of blood flow to the brain like strokes, vascular dementia, as well as Alzheimer’s disease.  Ainslie PN, et. al in the Journal of Physiology showed that aerobic activity increases blood supply to the brain both during and after exercise. Preliminary research suggests that aerobic exercise may indeed prevent the decline of brain function that has been associated with these diseases and age related decline. Decreased brain blood flow has also been implicated in “brain fatigue,” that feeling of sluggishness that comes for instance after a poor nights sleep.  Perhaps, this may explain why exercise improves mood, overall energy and sense of well-being, as well as decreases the severity of depression in sufferers.

So what’s the take home message? While this area of research is in its infancy, suffice to say, the research certainly suggests that we should all exercise aerobically regularly, as long as it is safe to do so as determined by your physician or health care provider.

References:
1)    Tanaka, Hirofumi. Cerebral Blood Flow: Sleeping Beauty Awakened by Exercise. Exercise and Sport Sciences Reviews. 2009:37: 111
2)    Ogoh S, Ainslie PN. Regulatory mechanisms of cerebral blood flow during exercise: new concepts. Exerc. Sports Sci. Rev. 2009; 37: 123-9
3)    Ainslie PN, Cotter JD, George KP, et al. Elevation in cerebral blood flow velocity with aerobic fitness throughout healthy human ageing. J. Physiology. 2008; 586:4005-10

Posted by rpaul / July 7, 2009 12:54 pm / Permalink / Comments (1) / Trackbacks (0)