Most people know that moderate exercise is great for your health. But according to research, surprisingly few of us know exactly what “moderate exercise” means. Gretchen Reynolds of the New York Times writes: “An instructive new study in PLOS One found that many of us underestimate how hard we should exercise to achieve maximum health benefits, and overestimate how vigorously we are actually working out.”

So how much exercise should we really be getting? According to the United States Physical Activity Guidelines for Americans, adults should engage in at least 150 minutes of moderate-intensity per week, or 75 minutes of vigorous-intensity aerobic exercise per week, in order to enjoy the significant health benefits they're after. Any activity is acceptable as long as the specified intensity is reached and maintained—whether it be gardening, water aerobics, or hiking. But it turns out that people have difficulty judging the intensity of their workout, and often miss the mark. 

Gauging exercise intensity

In a 2014 study published in PLOS One, researchers from York University in Toronto enlisted 129 adults aged 18 to 64 with the goal of understanding what they know about exercise and health. The majority of people were young, normal weight men and women with poor cardiovascular fitness.    

Participants were asked if they were familiar with the Canadian Physical Activity Guidelines. 80 percent indicated that the guidelines were easy to understand, and 57 percent reported that they met the minimum guidelines of 150 minutes of moderate intensity activity per week.

The participants were informed that “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’.”

When put to the test, however, the majority of adults underestimated the intensity of physical activity required to attain health benefits. Though participants accurately estimated light effort physical activity, they drastically underestimated moderate and vigorous effort, even after being provided with specified heart rate levels to gauge exercise intensity.  

Talk it out

Setting tangible intensity benchmarks is a better way to gauge how hard you’re actually working.  According to the Center for Disease Control, the talk test is a simple way to measure relative intensity. “As a rule of thumb, if you're doing moderate-intensity activity you can talk, but not sing, during the activity. If you're doing vigorous-intensity activity, you will not be able to say more than a few words without pausing for a breath.”

The perceived purpose of exercise can also impact eating habits, according to a related 2014 study published in Marketing Letters: A Journal of Research in Marketing. Researchers found that labeling a physical activity as “fun” reduced the amount of calories consumed, the amount of food served, and the choice of a healthy snack over junk food, whereas labeling an activity as “exercise” contributed to overeating.

Your takeaway? Seek activities that you look forward to rather than dread. “Listening to music during a run, making phone calls during a walk, or watching a video during a treadmill routine may be more related to weight loss success and perseverance,” the study concludes.