This is great news—really great news—for everyone.
Remember when we all first started talking about “aerobic” exercise (this goes back decades), and we were told that our heart rates had to remain elevated for at least 20 consecutive minutes to get any benefit? That’s why we exercised our patooties off in so many long Jazzercise classes back in the ’70s and ’80s. And that’s why some people who thought they didn’t have the time or stamina to work out for 20 minutes felt that there was no point in exercising at all.
Fast-forward to the first decade of the new millennium, when experts discovered that shorter bouts of exercise—just 10 minutes rather than 20—were enough to confer benefits, so long as a person reached a weekly total of 75 minutes of vigorous exercise or 150 minutes of moderate-intensity exercise.
The problem is, fewer than 4% of American adults do reach that goal.
Now the great news: A recent study reveals an easier way to hit that target, providing a motivational boost for exercisers and nonexercisers alike. What’s the secret? Every single minute of brisk activity counts when it comes to better health, even if you don’t clump those minutes together in bunches of 10. In other words, even a one-minute workout does a body good! Here’s why…
After the 20-minute-minimum mandate gave way to the 10-minute-minimum recommendation, researchers started wondering whether even shorter bursts of activity might be beneficial. They also wanted to know just how intense the activity had to be to show a benefit.
They used data from the ongoing National Health and Nutrition Examination Survey, in which participants undergo in-depth interviews and full physical exams. The analysis for the new exercise study also included data gathered when, for seven days straight, 4,511 participants wore accelerometers, devices that track the duration and intensity of movement measured in counts per minute (cpm).
Based on the accelerometer data, researchers created four categories of physical activity…
The higher-intensity long bouts correspond to the Centers for Disease Control and Prevention’s current recommendations, while allowing for the brief interruptions that may come when incorporating physical activity into normal living (such as pausing during a brisk walk before being able to cross the street and continue). Also, because there’s some controversy on exactly what constitutes moderate versus vigorous activity, the researchers looked at two commonly used thresholds of 760 cpm and 2,020 cpm. (I’ll translate activity level into real-life terms below.)
Most participants logged the majority of their activity in lower-intensity long bouts, while higher-intensity activity was primarily logged in very short bouts of one or two minutes.
Looking only at higher-intensity long bouts, women logged an average of just 46 minutes of high-intensity long-bout physical activity per week, while men logged 61 minutes…so both genders fell short of the recommended target. But: When shorter bouts of higher-intensity activity were factored in, women averaged 144 minutes per week and men averaged 246 minutes per week…a much more encouraging showing.
Then came the real test—determining whether those minute-long mini-bouts of activity actually did a body good. To that end, researchers looked at the participants’ body mass index (BMI) data. Of course, BMI isn’t the only measure of health and well-being, but a great many health risks are reduced when BMI is kept down within the normal range.
After adjusting for other factors that affect BMI (age, calorie intake, smoking status, etc.), the researchers found that lower-intensity activity was not associated with any differences in BMI. But higher-intensity activity was another story…
For women: Each minute of higher-intensity activity—whether from a short or long bout of activity—was associated with a better BMI. For example, for a typical 5-foot, 5-inch woman, each daily minute of higher-intensity activity had the equivalent calorie offset of 0.41 pounds for short bouts and 0.26 pounds for longer bouts. So if you were to compare two such women who followed the same diet, the woman who engaged in just one more minute per day of higher-intensity short-bout activity would weigh 0.41 pounds less than the other woman. Do the math and this can add up. If one woman typically gave that quick one-minute burst of activity just 10 times in the course of her day, she would weigh four pounds less than the other—which is the difference between having pants that fit and pants that don’t.
For men: Each minute of higher-intensity activity per day had the equivalent calorie offset of 0.27 pounds for short bouts and 0.20 pounds for longer bouts—again showing that short bouts of activity did have an impact. Analyzed another way, the researchers said, each extra minute per day of higher-intensity short-bout activity was associated with a 2% drop in a man’s likelihood of being obese.
The researchers were not sure why lower-intensity activity was not associated with lower BMI. It could be that only higher-intensity activity triggers the secretion of hormones that cause more calories to be burned even after a bout of exercise ends.
Why this is good news: For many people, short bouts of activity are much easier to accrue than long bouts—so a little extra effort can have an important health payback in terms of weight. Remind yourself, for instance, that it really is worthwhile to pick up your walking pace and to take the stairs instead of the escalator. Working such short little bursts of higher-intensity activity into your day absolutely adds up to better health!
Here are the cpm ratings (according to an earlier study from the University of Massachusetts, Amherst) for some everyday activities that qualify as “higher-intensity”…
