No time to exercise? Can’t afford a gym membership? Not to worry. Shoveling snow, raking the leaves, lugging laundry up the stairs, or pacing while chatting on the phone may be as effective as a formal workout — provided those short bursts of activity add up to 30 minutes a day, according to a new study.
Researchers at Oregon State University analyzed data on physical activity and markers of health such as cholesterol and blood pressure for more than 6,000 people ages 18 to 85, who had participated in the National Health and Nutrition Examination Surveys (NHANES) from 2003 to 2004 and from 2005 to 2006. NHANES is a program of studies that regularly assesses the health and nutritional status of American adults and children.
All the participants in the new study — their mean age was 48 — had worn an accelerometer, a device that measures movement, as they went about their daily lives. Only people who wore the accelerometer for 10 or more hours a day for at least four days were included in the new analysis. Using one-minute time periods, the tool calculated time spent doing routine activities as well as structured exercise sessions. Each study volunteer's blood pressure; triglyceride, LDL cholesterol and glucose levels; C-reactive protein; waist circumference; and body mass index, or BMI, were also measured.
After crunching the data, the researchers found that 43 percent of people who participated in bouts of 10 minutes or less of physical activity multiple times during the day — the so-called "active lifestyle" approach — met federal guidelines for being active. Slightly less than 10 percent of people who did longer, more structured bouts of exercise met the guidelines.
Those guidelines recommend getting at least 150 minutes a week of moderate-intensity aerobic activity — about 30 minutes a day — or 75 minutes a week of vigorous-intensity aerobic activity, or an equivalent combination of the two.
Not only did more people in the active lifestyle group meet federal guidelines, but also they fared as well as people who exercised for longer stretches in key measures of health, such as C-reactive protein, blood pressure, HDL cholesterol, waist circumference and metabolic syndrome.
For example, people who did short bursts of physical activity had an 89 percent chance of not having metabolic syndrome compared to 87 percent of people meeting federal guidelines with structured exercise. The one exception: Lifestyle exercisers didn't do as well as longer-bout exercisers in the BMI department. Their body mass index was slightly more than 1.5 points higher than the BMI of people who did structured exercise. While that may not sound like much, it translates into a 10- to 15-pound difference, enough to move someone from the overweight to the obese category, said study co-author Brad Cardinal, co-director of the sport and exercise psychology program at Oregon State.
"This study changes the way we think about activity," Cardinal said. Ten minutes of physical activity here and 10 minutes there "really does add up," Cardinal said. "Seeking out those opportunities to be active truly makes a difference in your health."
It is important that those short bouts of physical activity be of moderate to high intensity, Cardinal said, the equivalent of walking at about a 3.5- to 5-mile-per-hour pace. Even if your pace is slow, you can up the intensity by toting a heavy load, such as a backpack or a toddler.
"Extra load generates greater work on the body," Cardinal said. "When you do a higher intensity activity, you see extra benefits." For example, walking up and down stairs for 10 to 15 minutes — no easy feat — is the equivalent of a trip to the gym for most people, he added.
Doing short bursts of moderate to intense activity is "a more natural way to live," Cardinal said. "Movement and physical activity represent life. If we look at cells in a petri dish, the living ones are the ones moving."
That's not to say that if you're a committed exerciser or diehard gym rat you should forsake your usual workouts.
"I personally haven't missed a day of exercise since October 1, 2009," said Cardinal, who works out for an hour daily. Even so, he said he still looks for opportunities to build activity into his day, from doing jumping jacks in his office to taking the first parking spot he sees even if it is far from his destination. "Periodic activity breaks wake up my body," he said. "There are also some additional health benefits associated with doing more activity, though we didn't look at this directly in this study."
However, it's good to know that short bouts of activity may prompt exercise devotees who can’t find time to work out on a given day to at least do something, and may nudge people who hate formal exercise to squeeze physical activity into their life.
"People get it in their minds, 'If I don't get that 30 minutes a day I might as well not exercise at all,'" Cardinal said. "Our results give people meaningful, realistic options for meeting the physical activity guidelines."
Pass It On: Short bursts of physical activity are as good for health as longer workouts.