May 8, 2012 -- Is the morning commute grinding your gears? It might also be hurting your health.
People who drive long distances to work are more likely to be overweight than their non-commuting counterparts, according to a new study that links urban sprawl with expanding waistlines.
"It could just be a function of having less discretionary time to be physically active," said Christine Hoehner of Washington University in St. Louis, Mo., lead author of the study published today in the American Journal of Preventive Medicine. "Or it could be related to people burning fewer calories because they're sitting longer."
Previous studies have tied time spent sitting to an increased risk of cardiovascular disease, cancer and early death.
To tease out the health effects of the daily drive, Hoehner and colleagues studied the medical records of nearly 4,300 commuters in Dallas-Fort Worth and Austin, Texas. They found the more people drove, the less they exercised.
"I think the message for folks who live a long way from work and have a desk job is to find ways to build physical activity into their day," said Hoehner, adding that workplaces should "allow and even encourage physical activity breaks."
Hoehner said diet could also be to blame, theorizing that commuters have less time to cook and more time to snack in the car.
Weight wasn't the only thing that increased with driving distance: The longer the drive, the higher the driver's blood pressure.
"Previous studies have pointed to daily exposure to traffic, particularly the unpredictability of traffic, as being a source of chronic stress," said Hoehner, describing how frustration can send blood pressure through the roof. "Our study is the first to show that long commutes are associated with higher weight, lower fitness levels and higher blood pressure, all of which are strong predictors of heart disease, diabetes and some cancers."
Roughly 28.5 million American adults travel 30 minutes or more to work, according to 2010 U.S. census data.
"Driving to work has become a part of American life. But there's no reason that taking walks during work breaks can't become part of daily life, too," said Hoehner.
A 2011 study of 21,000 Swedish workers found those who commuted by car or public transit reported more stress, exhaustion and missed work days than those who walked or bicycled to work. But few American cities are built for active commuters.
"We've engineered physical activity out of our lives," said Hoehner. "We need to change our communities and make improvements to the infrastructure to make the healthy choice the easy choice."
Dr. Redford Willams, director of Duke University's Behavioral Medicine Research Center, said commuters should make opportunities for physical activity during the work day.
"Even if it's no more than walking up three flights of stairs and back down again, it's going to be good for your physiological and psychological health," said Williams.
And during the drive, when traffic is at a standstill, tell yourself, "there's nothing I can do about it," Williams said.
"Instead of fuming at the slowness as you're sitting there in line, take a deep breath and say, 'There's no way I can make those people go faster, so I might as well just chill,'" he said. "Have some books on tape, or something fun to occupy your mind."