A new study in Archives of Internal Medicine attempts to answer the question of whether exercise counteracts the negative effects of being overweight or obese. The short answer is "not really," although the long answer is interesting for several reasons.

Let's start with the highlights, quoting from the Associated Press news report:

The first big limitation of the study is that it relied on self-reporting. (The MPF reader who gave me the heads-up flagged this; based on his experience in the health-care industry, he said, you always have to use caution with self-reported results.)

The second is that the definition of "exercise" leaves out strength training. Here's a direct quote from the paper:

The third problem is a near-total lack of consideration for the intensity of exercise. (There's one interesting exception, which I'll get to in a moment.)

Another problem arises from the way the story is reported. The headlines hone in on the "fit but fat" angle, but really, the researchers didn't measure fitness.

Let me say that again, in italics: The researchers didn't measure fitness.

They assessed physical activity, which is different. There were no treadmill tests to measure maximal oxygen uptake (VO2max), or timed 1.5-mile runs, or any other measure of fitness or performance. (And, of course, there were no assessments of strength or muscular endurance either.)

That's why there's an apples-and-oranges disconnect with these quotes toward the end of the story:

As I said, Blair's point refers to a separate issue, and I'm not sure if it's truly an important one. Since body size and VO2max are both strongly linked to one's genetics, someone could be born to be fat and fit. A treadmill test would only confirm that this unusual pairing of familial tendencies puts one at low risk of heart disease, despite appearances to the contrary.

Measuring physical activity strikes me as more democratic, since it's something an individual can actually control (to a point, I mean; I understand that some people are predisposed to be more active than others). Which brings me to a couple of interesting findings:

• If you look at this table, the "time spent walking" category shows what you'd expect at the extremes: Women who reported walking the least had the highest risk of heart problems, while the ones walking the most (four or more hours a week) had the lowest risk. But in between there's a non-linear glitch: Women who walk two to three hours a week had slightly higher risk than women who walk between one and one and a half hours.
• We get a glimpse of the benefits of higher-intensity exercise in the "usual walking pace" category. Women who report walking 3 mph or faster have much lower heart-disease risk than women who report walking slower. My guess is that this is one of the least-accurate categories of self-reporting -- I mean, unless you're on a treadmill, how do you know how fast you're walking? -- but if nothing else it probably indicates that if you think you're walking at a brisk pace, you get the benefit anyway.

Tuesday blog meat

• Syphilis: it's a tale of adversity, survival, and ultimate triumph (for the pathogen, not the unfortunate humans hosting it).
• Here's the ugly truth about cosmetic surgery.