Health officials are always encouraging those of us who can to lace up our walking shoes and go for a stroll.

And with good reason. Walking has been linked to a variety of health benefits, including a lower risk of dying prematurely from heart disease, stroke, type 2 diabetes, and breast and colon cancer. It can also help improve our mood.

We’re told to do our walking at a “brisk” pace. That way we can meet the minimum exercise recommendations of many U.S. health guidelines: either 150 minutes of “moderate-intensity” physical activity or 75 minutes of “vigorous-intensity” physical activity weekly.

But what exactly does “moderate” or “vigorous” — or even “brisk” — mean in that context? And how do we know if we’re achieving those levels of intensity when we’re walking — without, that is, having to do all those pulse measurements and math calculations to figure out our “target heart rate”?

Counting the steps

A study published recently in the International Journal of Behavioral Nutrition and Physical Activity offers some help. It provides new evidence for a simple and reliable way of measuring exercise intensity: counting the cadence of our steps.

For adults aged 21 to 40, walking about 100 steps per minute constitutes moderate intensity, the study found. And upping the pace to 130 steps per minute shifts the intensity to vigorous. (Running, which is also vigorous activity, generally begins at around 140 steps per minute.)

“This research establishes a very practical method to measure the intensity of walking, one that is very easy to communicate and also rigorously validated by the science,” says Catrine Tudor-Locke, the study’s lead author and a kinesiologist at the University of Massachusetts Amherst, in a released statement.

All you have to do is count your steps for 15 seconds and then multiply by four. That will give you the approximate intensity level of your walking workout.

This isn’t the first study to propose 100 steps per minute as a reasonable rule-of-thumb measure of moderate-intensity walking. But it does appear to offer the most rigorous evidence to date in support of that suggestion.

Study details

For the study, Tudor-Locke and her colleagues brought 76 healthy men and women in their 20s and 30s into a lab where they walked on treadmills at various speeds. The researchers counted the participants’ steps and computed the intensity at which they were doing the activity, using something called metabolic equivalents of task, or METs.

Moderate-intensity activity is generally defined as movement that requires 3.0 METs — or three times the amount of oxygen that a person would consume while sitting still. The lower limit of vigorous-intensity exercise is generally defined as 6.0 METs.

For the participants in the current study, moderate-intensity walking began at about 2.7 miles per hour — or at a pace of about 102 steps per minute.  Vigorous-intensity walking (six METs) began at about 4 miles per hour — a pace of about 129 steps per minute.

Interestingly (and encouragingly) the researchers found that the natural walking pace of 90 percent of the study’s participants was at the moderate-pace level. In fact, some of them struggled to walk at a slower pace.

“If you just tell people to walk at their normal speed, they probably are going to walk about 100 steps per minute,” says Elroy Aguiar, one of the authors of the study and a postdoctoral researcher at the University of Massachusetts at Amherst in a released statement.

Precise pace may vary

The pace recommendations that emerged from this study are heuristic — in other words, they are, as the researchers explain, “grounded in evidence, but may not be necessarily precise.”

Leg length, height, weight, gender and other factors will, of course, affect the precise number of steps that constitute moderate or vigorous activity for any individual walker.

Furthermore, the findings apply only to adults aged 21 to 40.

But it looks as though we’ll have steps-per-minute recommendations for older adults soon. Tudor-Locke and her colleagues are continuing their research to figure out walking-intensity thresholds for two more groups: people in their 40s and 50s and those aged 60 and older.

In the meantime, if you fall into one of those older age groups, just keep walking at any pace you can.

As Aguiar notes, “walking for exercise is a low-cost, low-skill, feasible activity choice which has the potential to drastically improve people’s health.”

“Our society has engineered movement out of our life,” he adds. “We have TVs, we have cars, we have remotes. It’s clear that you can achieve the public health guidelines for physical activity through walking.”

FMI: The International Journal of Behavioral Nutrition and Physical Activity is an open-access publication, so you can read the study in full on the journal’s website.