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How Hard Are You Really Working Out?

A new Canadian study suggests that most adults are clueless about the intensity of their exercise. Researchers from Toronto’s York University recruited 129 inactive Canadians ages 18 to 64 to see what they know about strenuous workouts. Canadian guidelines specify that during moderate exercise your pulse rate should rise to between 64 to 76 percent of your maximum heart rate, and for vigorous exercise between 77 and 90 percent. U.S. guidelines say you should be able to "talk but not sing" during moderate exercise, and not be able to say more than a few words without pausing for breath during vigorous exercise.

Once they positioned their volunteers on treadmills, the Canadian researchers found that few were able to achieve and maintain a heart rate of 65 percent of their maximum during what they believed was moderate exercise, and even fewer were able to maintain a heart rate of 75 percent of maximum when they believed they were exercising vigorously. The researchers found that during every test, participants overestimated the intensity of their exercise.

To determine whether you’re meeting your intensity goals, you should take your pulse frequently during exercise, and if it remains below 65 percent of your maximum heart rate, step it up! The researchers also noted that the most accurate way to calculate your maximum heart rate is to subtract 64 percent of your age from 211.

My take? I don’t think it is necessary to calculate your target heart rate and take your pulse frequently during aerobic exercise to reap its benefits. I feel such monitoring can make workouts less enjoyable. If exercise is not fun, or if you do not see benefits from it fairly quickly, your motivation to continue may erode. If a period of aerobic exercise does not leave you feeling that you have labored, with your heart beating faster and your breathing stimulated, you likely have not performed it vigorously enough. If it leaves you collapsed on the ground painfully gasping for breath, you've probably overdone it. I think most people can figure out the right level of intensity without taking their pulse, consulting tables and charts, and worrying about whether they are in the target heart rate zone.

Jennifer L. Kuk, “Individuals Underestimate Moderate and Vigorous Intensity Physical Activity,” PLOS One, DOI: 10.1371/journal.pone.0097927