July 14, 2009

Study: Active Commuters Generally More Fit

According to a recent study examining more than 2,000 middle-aged Americans, walking or biking even a portion of the distance to work "” something done by only a small fraction of U.S. adults "” is linked to a higher level of overall physical fitness.

The study found that only around 17 percent of city-dwellers walk or ride a bicycle for any stretch of the way to their place of employment. Those who did, however, performed significantly better on treadmill fitness tests, even after researchers factored in their non-work-related physical activities. 

On other key health indicators like body mass index, blood pressure, insulin and triglyceride levels, male participants who actively commuted also had healthier numbers compared to their carpooling counterparts.  For women, however, the results were less pronounced.  Researchers noted that women tended to walk or bike shorter distances than males and the authors speculate that they likely do so at a slower pace, possibly leading to the gender discrepancy.

Experts blame dilapidated sidewalks, non-existent bike paths and discouragingly long distances for the abysmally low number of Americans who opt for an active commute to work.

"I would love to bike to work, but it is completely unsafe for me to do so," explained Penny Gordon-Larsen Ph.D. of the University of North Carolina at Chapel Hill, who spearheaded the study published in Monday's Archives of Internal Medicine. "There's one real small, narrow area where there's no bike lane."

Gordon-Larsen says she takes the car to work, but walks her kids to school beforehand.

The group's research was imbedded in a larger federally sponsored study on heart disease and included 2,364 participants in several major U.S. cities including Chicago, Minneapolis and Oakland.  The subjects took fitness tests and filled out a questionnaire about their daily commute to work during the previous year.

From the outset, researchers understood that their study had a rather significant methodological glitch: Participants already leading a generally active lifestyle were most likely the ones who also opted for an active commute, thus making it extremely difficult to isolate the effects of walking or riding a bike to work.  As Gordon-Larsen explained, it's a two-way street, with generally active people being more inclined to walk or bike to work, while sedentary people likely have a hard time mustering up the motivation to ditch the car and hop on a bike. 

Previous international studies have identified significant connections between countries where a large number of people bike or walk frequently and low levels of obesity. Prior to this study, however, little focus has been devoted to examining the comparative health status of Americans who bike or walk to work, explained James Sallis of San Diego State University.

"I'm really glad to see people starting to take a look at this in the U.S.," said Sallis, who researches environmental factors and government policies that influence physical activity.

Interestingly, Sallis explains that city zoning laws in the U.S."”which often create large distances between business districts and the homes of workers"”may play a significant factor in discouraging Americans from making a more physically challenging commute to the office.

"You're building in the impossibility of actively commuting to work," Sallis said.

Some cities such as Portland, Oregon have begun constructing bike paths in and around the city and have witnessed a significant jump in the number of people cycling to work.  At the same time, a number of local companies have responded by providing areas for employees to shower and change as well as secure areas to park their bikes.

The group's results corroborate evidence from previous studies showing that that walking or biking to work is physically beneficial.

"Public support for policies that encourage active commuting has been shown," wrote the group, "particularly for individuals with experience using active commuting and with positive attitudes toward walking and biking."

"Furthermore, increasing active commuting will have the dual benefits of increasing population health and reduction of greenhouse gas emissions. Environmental supports for commuting, such as physical environment and socio-cultural factors, have been shown to promote active forms of commuting."


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