New research finds that short bouts of intense exercise can help an individual maintain or even lose weight.
The finding is contrary to traditional exercise prescriptions that have encouraged moderate activity to elevate heart rate for at least 10 t0 30 minutes.
In the study, University of Utah researchers found that even brief episodes of physical activity that exceed a certain level of intensity can have as positive an effect on weight as does the current recommendation of 10 or more minutes at a time.
“What we learned is that for preventing weight gain, the intensity of the activity matters more than duration,” said professor Jessie X. Fan, Ph.D., professor in the department of family and consumer studies.
“This new understanding is important because fewer than 5 percent of American adults today achieve the recommended level of physical activity in a week according to the current physical activity guidelines. Knowing that even short bouts of brisk activity can add up to a positive effect is an encouraging message for promoting better health.”
The current physical activity guideline for Americans is to get at least 150 minutes of moderate to vigorous physical activity, or MVPA, a week, which can be accumulated in eight to 10 minute periods.
MVPA is defined as greater than 2,020 counts per minute measured with a tool called an accelerometer.
For an average person in an everyday setting without a fancy gadget to gauge the exertion, that would translate roughly to a walking speed of about three mph. But taking the stairs, parking at the far end of the lot, and walking to the store or between errands are choices that can add up and can make a positive health difference, the researchers note.
The study shows that higher-intensity activity was associated with a lower risk of obesity, whether in “bouts” of fewer or greater than 10 minutes.
This may be especially important news for women, who were on average less physically active than men.
However, neither men nor women came close to the weekly 150-minute recommendation with bouts of eight to 10 minutes.
Nonetheless, when adding shorter bouts of higher-intensity activity, men exceeded the recommendation on average, accumulating 246 minutes per week, and women came close, at 144 minutes per week on average.
Researchers say that this shows that a little more effort can have an important health payback.
For the study, published in American Journal of Health Promotion, subjects were selected from the National Health and Nutrition Examination Survey, NHANES.
NHANES is a national program that has been collecting health and nutrition data from a representative sample of adults and children in the United States since 1999. From 2003 to 2006, participants in the survey wore accelerometers for seven days, which captured data on their physical activity.
This information was in addition to the broad range of demographic and health-related information collected in the NHANES program from interviews and physical examinations.
Researchers studied 2,202 women and 2,309 men from 18 to 64 years of age, excluding women who were pregnant or individuals with impairments that compromised their ability to walk. Researchers compared measurements of physical activity based on length of time and intensity.
Four categories were created: higher-intensity bouts (greater than 10 minutes exertion at greater than 2,020 counts per minutes, or CPM), higher-intensity short bouts (less than 10 minutes at greater than 2,020 CPM), lower-intensity long bouts (greater than 10 minutes and less than 2,019 CPM), and lower-intensity short bouts (less than 10 minutes and less than 2,019 CPM).
The study used body mass index, BMI, to measure weight status. A BMI between 18.5 and 24.9 is considered normal weight, whereas a BMI between 25 and 29.9 is overweight; and over 30 is obese.
Results show that for women, each daily minute spent in higher-intensity short bouts was related to a decrease of .07 BMI.
That is, each such minute offset the calorie equivalent of .41 pounds. This means that when comparing two women each 5-feet-5-inches tall, the woman who regularly adds a minute of brisk activity to her day will weigh nearly a half-pound less.
Results were similar for men. Importantly for both, each daily minute of higher-intensity activity lowered the odds of obesity — 5 percent for women, and 2 percent for men.
Source: University of Utah