ATLANTA - When Seema Shrikhande goes to work, she drives. When she takes her son to school, they drive. And when she goes shopping, to the bank or to visit friends, she gets into her car, buckles up and hits the road.

Driving is a way of life for Americans but researchers say the national habit of driving everywhere is bad for health.

The more you drive, the less you walk. Walking provides exercise without really trying.

Ideally, people should take 10,000 steps a day to maintain wellness, according to James Hill, professor of pediatrics at the University of Colorado.

But for those who only walk from their home to the car and from their car to an office and back again, that figure can sink to only 1,000 steps.

A car culture forces people to make time to exercise and driving long distances reduces the time available to work out.

If it (Atlanta) was a city where I walked more I would automatically get a lot of the exercise I need. Now I have to ... schedule it into my life. Sometimes it's very difficult because I'm busy, said Shrikhande, a professor of communications at Oglethorpe University in Atlanta.

Obesity and heart disease are two of many problems associated with a sedentary lifestyle.

Car dependence makes it harder to get the 75 minutes of intense weekly exercise or the 150 minutes of moderate exercise the government recommends, said Dr. Dianna Densmore of the Centers for Disease Control and Prevention.

Lawrence Frank of the University of British Columbia has even quantified the link between the distance people drive each day and their body weight.

Every additional 30 minutes spent in a car each day translates into a 3 percent greater chance of being obese, he said. People who live in neighborhoods with a mix of shops and businesses within easy walking distance are 7 percent less likely to be obese.

READJUSTING THE BALANCE

Older cities such as New York, Boston and Chicago contain neighborhoods built around a grid of densely populated streets and tend to have more public transport.

But fast-growing newer cities like Atlanta, Dallas and Phoenix are surrounded by sprawling suburbs that can only be navigated behind the wheel, not least because fiercely hot summers limit the attraction of walking.

Shrikhande said that as a student in Philadelphia she didn't own a car and walked a lot but in Atlanta car reliance was a small price to pay for a lifestyle whose benefits include better weather and living in a leafy suburb.

Health is just one factor that has caused town planners to seek alternatives to driving-only towns. High gas prices, a desire for more tightly knit communities and environmental concerns also play a role.

Atlanta is seeing a rise in inward migration as people move back into neighborhoods around the city center.

But the question of how to readjust the balance away from car dependence and toward sidewalks, cycle lanes and denser communities is intensely political.

Groups worried about climate change and others promoting a healthier lifestyle are lobbying for a new federal transport bill that shifts policy toward alternatives to car use.

We have designed cities to suppress walking, said David Goldberg of Smart Growth America, a coalition of nonprofit groups that works to improve town and city planning. It's much easier to widen highways in an ... exurb than to get money to retrofit an over-wide highway for non-driver..

In a country where the car is a symbol of freedom, efforts to promote alternatives are caricatured as social engineering or a bid to undermine the country's spirit by powerful lobbies representing the transportation and construction industries.

Even so, efforts are underway. In Atlanta, local governments have devised strategies to promote urban living, said Dan Reuter of the Atlanta Regional Commission.

The city is also exploring building light rail to connect northern suburbs with the center and has embarked on a project to link a disused Beltline tram loop around the city center with parks, communities and business, he said.

A CULTURAL THING

In interviews, commuters reflected on the impact of spending hours each week in their cars.

It's a total drain on my children, said Krystal Barrett, who drives her two sons to school each morning across Atlanta's northern suburbs -- a 45 minute journey on a good day.

Barrett and her husband want to move closer to work, school and church. Meanwhile, she often breaks the long journey home to let her two mall boys burn off energy at a playground.

But other commuters said they drove out of habit so ingrained it became a state of mind.

Francis Charfauros, a coffee shop manager in Scottsdale, Arizona, said he would drive to work at his previous job even though it was just a few yards away.

I don't know why, he said. It's a cultural thing.

(Additional reporting by Tim Gaynor in Phoenix; Editing by Alan Elsner and Pascal Fletcher)