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Your workouts might feel hard, but according to new research, we're not very good at determining what "hard" really is. (Photo: blyjak/ThinkStock)

Am I Estimating My Workout Intensity Correctly?

heart rate monitor intensity moderate vigorous exercise fitness pace outside online outside magazine

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How do we put this nicely? If you’re anything like the participants in a recent Canadian study, you’re probably wrong about your workout intensity. (And yes, you probably are like them, considering that the group contained both men and women of different ages, ethnicities, and BMI classes.) People know what “light” exercise is, say researchers at the University of York in Toronto, but they tend to go too easy on themselves when asked to demonstrate moderate or vigorous effort—the level at which exercise provides some of its biggest performance benefits.

Specifically, when the 129 participants were asked to walk on a treadmill at the minimal pace they believed would provide health benefits, only 19 percent walked at a moderate pace and only 5 percent at a vigorous pace, according to their heart-rate monitors. On average, the group walked at an intensity of 57.46 percent of their maximum heart rate, while “moderate” effort is defined as anywhere from 64 to 76 percent.

They did this even after being given descriptions of each level of effort. For light effort: ‘‘you are starting to feel warm and you have a slight increase in breathing rate’’; for moderate effort: ‘‘you are warmer and you have a greater increase in breathing rate’’, and; for vigorous effort: ‘‘you are quite warm and more out of breath’.”

So where’s the disconnect? Lead author Jennifer Kuk, PhD, believes that health promotion efforts are actually working too well at making people think that exercise isn’t hard. “A common message is that physical activity is easier than you think to incorporate into our daily lives,” she says. And while light activity does have some benefits, she says, it’s the harder stuff that really makes a difference cardiovascularly.

People like routine, she adds, and don’t like to push themselves—they walk or jog at one speed, or lift the same amount of weights every week. “Then when they get fitter, they don’t adjust the intensity and don’t challenge themselves like they should.”

This is particularly troublesome, since research has shown that plenty of people admit to not getting the recommended 150 minutes a week of moderate to vigorous exercise. If those who do claim to get this amount are actually overestimating, Kuk says, the problem could be even more widespread.

The study also suggests that following cues like breathing, sweating, and feeling “warm” don’t work so well; they can also be influenced by outside factors like temperature, says Kuk. That’s why, if you have a weight-loss or performance goal in mind—or you simply want to make sure you’re getting adequate cardio workouts in each week—wearing a heart-rate monitor is your best bet at measuring accurate intensity.

Bottom line: If a large part of your weekly fitness regimen involves walking, jogging, or doing what you’ve always done (at what you think is a “moderate” pace), you may be overestimating your intensity—and the cardiovascular benefits you’re getting from it. Try working out with a trainer, pushing yourself in a group fitness class, or wearing a heart-rate monitor if you want to be sure you’re exercising in the right zone.