Most of us know that we should walk briskly for the sake of our health. But how fast is brisk?

A helpful new study of walking speed and health concludes that the answer seems to be about 100 steps per minute, a number that is probably lower than many of us might expect.

Current guidelines usually state that we should walk at a brisk pace rather than stroll leisurely. But the recommendations do not always define what brisk walking means.

Catrine Tudor-Locke, a professor of kinesiology at the University of Massachusetts in Amherst and her colleagues decided to see whether there was enough data available to develop a more precise and useful definition. They wound up with 38 studies that had included hundreds of men and women ranging in age from 18 to elderly and of many different BMIs.

But despite the differences in the participants, the data about what made their walking brisk, or "moderate," was consistent across all of the studies, Tudor-Locke said. "The good news is that this pace will probably not feel strenuous to most healthy people."

There were some small variations among people in the precise number of steps per minute needed to achieve brisk walking, she said. "For some people, it was 98; for others, 102. But 100 steps per minute is a good rule of thumb for almost everyone."

Unless you are older than 60. The ideal steps among older people were inconsistent. "Some older people needed to take quite a few more than 100 steps per minute" to walk briskly, she said, while others achieved briskness with lower step cadences.