Defining "moderate-intensity" exercise

 

Defining "moderate-intensity" exercise

Engage in moderate-intensity physical activity for a minimum of 150 minutes each week. That's the current national recommendation on physical activity. It's easy enough to understand, except for the "moderate intensity" part. Does that mean walking? So-called "brisk" walking? Jogging?

San Diego State University researcher Simon Marshall has come up with a practical rule of thumb for figuring out "moderate intensity" as it applies to walking: it's akin to taking at least 100 steps per minute.

To get to this definition, Marshall and his colleagues recruited 97 women and men. Each walked on a treadmill four times at four different speeds—from 2.4 miles per hour to 4.1—while a machine measured the amount of energy he or she was expending. The volunteers also wore pedometers to count their steps.

Complex calculations later, the researchers determined that walking at a speed of at least 100 steps per minute fulfilled the lower limit of moderate-intensity exercise (American Journal of Preventive Medicine, May 2009).

Aim for 100

This number, 100 steps per minute, is a useful guide. You can see how your pace stacks up to it using a few simple tools: a pedometer, a watch, a notebook, and a pencil.

A pedometer is a small device that, when clipped to your belt or pocket, records every step you take. Some have advanced features that calculate how far you have walked or how many calories you've burned. You can buy one for as little as $5 or as much as $50.

To calculate your steps per minute, put on your pedometer and head to your favorite walking spot. Walk at an easy pace for a few minutes to get warmed up. When you are ready, note the number on the pedometer. Walk for exactly one minute and note the new number on the pedometer. Subtract the starting number from the ending number and you have the number of steps you take in a minute. For an even more accurate estimate, walk for five minutes, and divide the number of steps you took by five.

If you cover more than 100 steps in a minute, great. The more intense your activity, the better it is for your heart. If you cover fewer than 100 steps a minute, think about gradually trying to pick up your pace.

Keep in mind that this 100-steps-per-minute figure is for generally healthy people with no physical limitations. And it's just a guide—the number of steps per minute that got people to the moderate-intensity mark ranged from 92 to 102 steps for men and 91 to 115 steps for women.

Other ways to gauge moderate intensity

There are other ways to gauge if your activity is in the moderate-intensity zone. Using a heart monitor, exercise so your heart rate is between 50% and 85% of your maximum heart rate (220 minus your age). Or do the "talk test." You are exercising at moderate intensity if you are breathing faster than normal but can still say a sentence or two out loud or sing a snatch of a favorite song. If you aren't the least bit out of breath, you are walking at low intensity; if you have trouble finishing a sentence, you are exercising at high intensity.

Engaging in moderate-intensity activity for 150 minutes a week is a good choice for many people. But it isn't an upper limit, nor is it right for everyone. Some people can't exercise that strenuously, or aren't ready to do so. Others prefer to exercise more vigorously for shorter amounts of time. If walking isn't your thing, try swimming, water aerobics, tai chi, bicycling, ballroom dancing, tennis, or any other activity that speeds up your breathing and makes your heart beat faster.