Friday, June 10, 2011

Exercise For Brain Health, Maybe

An interesting study with some predictable findings and some findings that were a bit of a surprise.

The study involved 1,238 people who had never had a stroke. Participants completed a questionnaire about how often and how intensely they exercised at the beginning of the study and then had MRI scans of their brains an average of six years later, when they were an average of 70 years old.

The brain scans showed that 197 of the participants, or 16 percent, had small brain lesions, or infarcts, called silent strokes. People who engaged in moderate to intense exercise were 40 percent less likely to have the silent strokes than people who did no regular exercise. The results remained the same after the researchers took into account other vascular risk factors such as high blood pressure, high cholesterol and smoking. There was no difference between those who engaged in light exercise and those who did not exercise.
Because this was not an intervention study, we don't know how much or how "intensely" the participants were exercising - and because I didn't look the study up, I don't know how "intensity" was quantified in this study.  I have met people who were convinced they were strong and worked out intensely who were in fact nearly pathologically weak. 

Further, there's kind of a chicken and egg thing - if you start having mini-strokes, do you think that might have an effect on how often and how hard you work out?  It reminds me of the study that showed that all of the 80+ year old folks in some big city or another lived in apartments for which there was no elevator, and they lived on the 2nd floor or above.  Does that mean if you walk up a flight of stairs every day you'll live to 80+?  Maybe, but it might mean that if you are healthy enough to walk stairs, you can stay in your 2nd floor apartment and if you aren't, you moved out.

Another chicken and egg issue involves diet.  If, as Taubes et al suspect, a poor diet affects activity level in the same way it affects health (short summary:  High carb diets create the starvation effect and therefore reduce activity level while accelerating metabolic derrangement), the folks who are eating a high carb, low fat diet will not be exercising as much or as hard - they'll be "too tired" and "won't feel like it" and they will also likely have higher inflammation levels ("I'm hurting today, I don't think we can work out"). 

IOW - the poor diet (which in my book means high carb, low fat) drives low activity level AND other negative health outcomes from metabolic derrangement.

Further, the high intensity folks, although they suffered these mini strokes at a much lower rate, were not immune.

In short, while the study shows a significant statisitical correlation with intense exercise and brain health, it cannot tell us why that correlation exists. 

However, I still advocate frequent, intense, and relatively short workouts for all the other benefits which can be quantified by the results those types of workouts create - more muscle mass, improved health bio markers, faster and more significant adaptation to the higher intensity stimulus, and reduction of the negative adaptation associated with excessive amounts of "cardio" training (muscle consumption, inflammation, joint trauma, inferior range of motion, and too much time spent working out).

For more on how the paleolithic model applies to aging well, I recommend Art De Vany's book, "The New Evolution Diet", which provides a potent mix of anecdotal perspective (Art is 70+ and strong as a bull after 30 years of living like a hunter/gatherer) and science (Art's a PHD and provides a plethora of science that comports with his premise).

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