Friday, November 21, 2008

What exactly is "moderate" exercise?

That's the question posed by a study in progress being done at the State University of New York and Syracuse University.

The Surgeon General recommends that everyone get 30 minutes a day of moderate exercise--but what, exactly, does that mean? Language is powerful but not always specific; what feels moderate to you might feel excessive to me, or maybe underwhelming.

Researcher Cameron Hall set out to explore people's perceptions of moderate exercise. I was lucky enough to be able to volunteer for the study, and it's been fun. On the first visit, I came into the lab, where they hooked me up to all kinds of monitors and meters and put me on a treadmill to measure my maximum exercise tolerance. They measured my oxygen consumption, heart rate, and perceived levels of exertion with one of those little charts where they ask you to point to how hard you think you're working. Pretty damn hard, by the end.

On the next visit, I was asked to walk around a track at what I thought was a moderate level of exercise. I booked it, let me tell you, wanting to surpass the researchers' expectations of me. I walked much faster than usual, averaging around 4 miles per hour instead of my usual 3.7. On the third visit, we were back in the lab, only now the researchers were telling me how fast and hard I had to work to hit the middle part of my range by the numbers.

It turned out that what I think of as moderate is nowhere near what the numbers say. Visit 3 was excruciating because we had to keep the treadmill flat for comparison purposes to the track we used on visit #2. I had to walk 4.2 miles an hour and even then could barely get into my moderate heart and oxygen consumption ranges. This might not have been a problem if I were, say, six feet tall. But I'm just about five one, and my legs just aren't that long.

So I learned what I personally have to do to get in the recommended half hour of "moderate exercise": Set that treadmill at 3.8 and crank up the incline to between 3 and 5 percent. I did it yesterday, and let me tell you, I was working hard. And that's what the researchers think will be the upshot of the study: You probably can't protect your cardiovascular health by strolling around the block with the dog or taking a leisurely stroll. You've gotta book it, baby.

What I love about this study is that it acknowledges both the power and pitfalls of language. Words are imperfect vehicles for expressing what we feel and what we know. But they're all we've got. Sometimes our task is to learn to use them more expressively. Sometimes, as in this case, our task is to connect them to cold hard facts.

The study results should be published within the next few months. I'll keep you posted.