Many overestimate exercise intensity, study shows

"Our study findings suggest that the majority of young and middle-aged to old adults underestimate the intensity of physical activity that is required to achieve health benefits," says Professor Jennifer Kuk, School of Kinesiology and Health Science. "This is worrisome both for personal and public health and well-being."

The 129 sedentary adult ages 18 to 64 recruited for the study, irrespective of their sex, ethnicity or BMI classifications, correctly estimated physical activities of light effort but underestimated moderate and vigorous effort, even after being given commonly used exercise intensity descriptors.

"We instructed volunteers to walk or jog on the treadmill at a speed which they felt corresponded to the 'light,' 'moderate' and 'vigorous' intensity descriptors used in the physical activity guide, yet they underestimated how hard they should be working to achieve moderate and vigorous intensity," lead researcher and graduate student Karissa Canning says.

Health Canada, as well as global physical activity guidelines using general terms to describe exercise intensity (determined by a given percentage of the maximum heart rate of an individual), recommend that adults ages 18 to 64 years should participate in two-and-a-half hours of moderate to vigorous physical activity per week for 10 minutes or longer at a stretch.

For adults to achieve a moderate intensity, their heart rates should be within the range of 64 to 76 per cent of their maximum heart rate and between 77 to 83 per cent for vigorous intensity, according to the Canadian and global physical activity guidelines.

Though there has been ample research that helped to develop the current guidelines, it is unclear whether individuals actually understand them as intended, notes Canning.

The Heart and Stroke Foundation funded study, "Individuals Underestimate Moderate and Vigorous Intensity Physical Activity" was recently published in PLOS ONE.