In my last posting called “Exercise, Stress and The Brain,” I wrote about the experiment that was done at the University of Colorado on the stress-reducing changes on the brain produced by exercise. In that experiment rats that ran for only three weeks did not show much reduction in stress-induced anxiety, but those that ran for at least six weeks did. “Something happened between three and six weeks,” says Benjamin Greenwood, Ph.D., a research associate in the Department of Integrative Physiology at the University of Colorado, who helped conduct the experiments. Then he goes onto say “It’s not clear how that translates” into an exercise prescription for humans. We may require more weeks of working out, or maybe less. And no one has yet studied how intense the exercise needs to be.

Imagine, here we are in 2010 with all the advancements in medical knowledge and we still can’t come up with some kind of universal exercise prescription? Interesting. Perhaps coming up with an exercise prescription is not a science, but maybe an art form. However, it’s hard for me to accept that medical science does not have a great deal to say about how much we should move our bodies. Perhaps it’s a mixture of both art and science. We can look at some recent studies to help us formulate  an exercise prescription for most people.

Again, I pulled some information out from an article that Gretchen Reynolds wrote in the New York Times a few weeks ago http://well.blogs.nytimes.com/2009/12/30/phys-ed-how-much-exercise-to- avoid-feeling-gloomy/.

A reading of the latest sports science report makes it clear that the “amount of physical activity necessary to produce health benefits cannot yet be identified with a high degree of precision,” according to the authors of the 2008 Physical Activity Guidelines for Americans report http://www.health.gov/PAGuidelines/, which was produced by the Department of Health and Human Services and was based on the recommendations of an advisory committee of scientists. These experts waded through dozens of studies on the health effects of exercise, looking at the impacts that exercise can have on people’s risks for heart disease, obesity, diabetes, cancer, depression and, in general, premature death.

Despite the inconsistent results, caused in some part by even more inconsistent methodologies between the different studies, the advisory committee did ultimately reach some conclusions about how much – or, really, how little – exercise we should be doing. So here goes:

The committee concluded that a person needs to accumulate a weekly minimum of two and a half hours of a moderate activity, such as walking. Or a person could spend half as much time (an hour and 15 minutes) on a more robust form of exercise such as jogging, according to this committee, to have similar health effects.

Interestingly, they did not find that exercise beyond a certain point conferred significant additional health benefits. That is to say, that people who are the least active to start with get the most health benefit from starting to exercise. People who already are fit don’t necessarily get a big additional health benefit from adding more workout time to their regimens. Which is not to say that if you are a devoted runner or cyclist, you should reduce your workout time in 2010. It’s just you’re already well ahead in terms of health benefits. According to the Physical Activity Guidelines report, “ It has been estimated that people who are physically active for approximately seven hours a week have a 40 percent lower risk of dying early than those who are active for less than 30 minutes a week.”

Now we are getting somewhere.

So what does this mean as you plan your 2010 exercise routines? First, because “activity affects so many organs and pre-disease states,” according to Frank Booth, a professor in the department of biomedical sciences at the University of Missouri at Columbia, who has extensively studied the health effects of exercise, “any activity is better than no activity.” The bottom line here is do something. Booth adds “Inactivity is looking more and more like the one of the underlying causes of many chronic diseases,” And lastly, he adds, “you want to live to be 100, then don’t just sit all day.” Well there you go. I guess the scientists do have something to say about exercise.

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