Hard Math: Adding Up Just How Little We Actually Move
By Sumathi Reddy, WSJ, March 11, 2013
Working out at the gym might not be enough to stay fit if you spend much of the rest of the day sitting down.
Americans are more sedentary than ever, government surveys show. That is a problem even among people who exercise regularly.
An increasingly popular way people are trying to coax more exercise into their lives is by tracking their movements using a bevy of small electronic devices from companies like Fitbit Inc., Jawbone and Nike. Some devices are pedometers, tracking steps. More sophisticated gadgets, known as accelerometers, measure the rate at which a person moves and convert this into calories expended.
"We've been very focused on exercise and making sure you get your half-an-hour a day of moderate and vigorous physical activity. But what we've not focused on so much is how you spend the rest of your day," says Bonnie Spring, director of the Center for Behavior and Health at Northwestern University.
Americans on average take 5,117 steps a day, according to a 2010 study published in the journal Medicine & Science in Sports & Exercise. A good daily goal, by contrast, is 10,000 steps, according to the American Heart Association and other experts. Research studies have found that such a regimen results in modest weight loss, improved glucose tolerance in people at risk of developing diabetes and other benefits, says David Bassett Jr., co-author of the 2010 study and a professor in the department of kinesiology, recreation and sport studies at the University of Tennessee.
Walking a mile roughly equals 2,000 steps. Climbing a flight of stairs--roughly 10 steps--is equivalent to taking 38 steps on level ground, Dr. Bassett says.
A study that followed more than 240,000 adults over 8½ years found that watching a large amount of television was associated with a higher risk of death, including from cardiovascular disease--even for participants who reported seven or more hours a week of moderate-to-vigorous exercise. The research, published in 2012 in the American Journal of Clinical Nutrition, used TV viewing and overall sitting time as a proxy for sedentary behavior.
"Our results suggest that exercise alone may not be enough to eliminate risks associated with too much sitting," says Charles Matthews, lead author of the study and an investigator with the National Institutes of Health. He says estimates from government surveys indicate that people's sedentary time outside of work has increased by about 40% between 1965 and 2009.
People who live in Colorado, where obesity rates are relatively low, take an average of 6,500 steps a day, a 2005 study found. By contrast, residents of Tennessee and Arkansas, where the obesity rates are much higher, take an average of 4,500 steps a day. "We don't know that it's cause and effect obviously, but the states with lower obesity rates have the higher number of steps," says James Hill, executive director of the Anschutz Health and Wellness Center at the University of Colorado.
All the movements a person does during the day--from getting up to close the garage to rocking in a chair--are non-scheduled physical activities that can make a big difference in terms of daily calorie expenditure by causing a person's metabolism to increase, says Gabriel Koepp, program manager of the Non-Exercise Activity Thermogenesis (NEAT) laboratory at the Mayo Clinic in Rochester, Minn. While walking is the main NEAT activity, other things can include washing the dishes instead of using a dish washer, making bread dough by hand rather than using a mixer, and even chewing gum, he says.
Health experts say people still need moderate to vigorous exercise, which has been shown to reduce risks of cardiovascular disease and other disorders. Dr. Bassett says a doctoral student in his department conducted a study in which 58 people watching 90 minutes of television marched in place in front of the TV during commercial breaks. "They increased their steps by about 3,000 per day just by doing this during commercials," says Dr. Bassett. "That's equivalent to about 30 minutes of walking." The study was published last year in the International Journal of Behavioral Nutrition and Physical Activity.
Pedometers have been shown, at least in the short term, to motivate some people to increase their daily activity if they chart progress toward a goal in a diary. More sophisticated accelerometers, with wireless synchronization, effectively log your progress for you.
In a 2007 analysis of several studies, people who used pedometers increased the number of steps taken by an average 2,491 a day and boosted overall physical activity by about 27% from previous levels, says Dena Bravata, a senior science affiliate at the Center for Primary Care and Outcomes Research at Stanford University.
Participants' body-mass index, a common measure of healthy weight, and blood pressure also declined, she says.
Eric Lent, of Atlanta, says starting to use an accelerometer made him "aware of how much time I was sitting in my office." The device--after he lost his Nike FuelBand, he replaced it with a Jawbone UP--motivates him to regularly work out and to be less sedentary through the day, says the 44-year-old chief marketing officer for an entertainment company.
Mr. Lent says he makes a point of parking in the farthest spot from the entrance to work. And he sets the Jawbone UP to vibrate if he is idle for 30 minutes or more. He aims to do 10,000 steps each day.
Carrie Mundy, a stay-at-home mom and photographer in San Diego, bought her Fitbit in February. She says she is regularly hitting 15,000 steps a day and has already lost 4½ pounds. To accumulate more steps, the 36-year-old says she walks down every aisle in the grocery store and makes extra trips back and forth when folding and putting away her laundry.
Ms. Mundy says her Fitbit also motivates her to get out and walk. "I'm constantly chasing these two people who I haven't caught up to," she says, referring to two friends whose total number of steps she can view on her device's display screen.
"It's like a videogame. I have such a competitive personality, so I'm going to beat these people today."
