Americans are increasingly obese and inactive; and urban designers, transportation planners and policy makers bear a large portion of the blame. This was the grim news delivered to some 230 health professionals, city and transportation planners, engineers, architects, pedestrian and biking safety advocates who attended Promoting Physical Activity and Health by Urban Design last week -- a conference sponsored by the Centers for disease Control and the Harvard Schools of Public Health and Design. Conference attendees were stunned to hear that the rate of adult obesity in the United States is three to four times higher than that found in similar populations in Europe. Climate is obviously not a factor, because the obesity rate in chilly Canada is 10 percent, one-third the rate seen in a similar demographic of U.S. citizens.

More dismaying was the news that these urban and transportation planners and policy makers are actually encouraging obesity with their own designs and policies. The researchers tied the epidemic of obesity in the United States and the subsequent explosion of diseases related to inactivity and poor nutrition, to the low and still declining rate of walking and cycling trips made by U.S. citizens over the normal course of everyday living, compared to their European or Canadian counterparts. Europeans make three to four times as many walking or cycling trips than their U.S. peers, according to research by John Pucher, Rutgers University professor of urban planning.

The discrepancy is particularly dramatic among groups of elderly Europeans and Americans. Walking increases with age in both Germany and the Netherlands, according to Pucher's research, while cycling falls off only slightly. Dutch and Germans 75 years of age or older make about half their daily trips by foot or bike, compared to only 6 percent of Americans aged 65 and older. While it's a very rare thing indeed to see an elderly cyclist in the United States, biking accounts for 25 percent of trips made by Dutch senior citizens, and 7 percent of the daily travel by Germans over the age of 75.

Equally stunning, walking is the mode of travel for 48 percent of Germans 75 or older, and 24 percent of their Dutch peers; this compares to 6 percent of the trips done by Americans over age 65. Their ability to perform routine tasks of living without auto dependency allows Dutch and German retirees to remain more self-sufficient and less isolated. All this exercise apparently does them good; both Dutch and German populations have a life expectancy three years longer than their American counterparts and a longer expectancy of healthy long life.

The stage had been set for the conference by a spate of jarring headlines about weight, exercise and health. In the previous week, a study had revealed that more than one-fourth of U.S. children under the age of two have televisions in their bedrooms and watch more than two hours of TV daily. A local woman had died following gastro bypass surgery, an increasingly popular treatment for obesity, at Brigham & Woman s Hospital, Boston. A report in London's Observer predicted that, untreated, the child obesity epidemic caused by lack of exercise and poor nutrition, could lead to the first drop in average life expectancy in over a century.

The researchers at the Harvard/CDC conference blame the bleak American activity profile on urban design trends over the last century that encouraged sprawl and kowtowed to the automobile, to the detriment of other transportation modes. While the move to suburbia made sense in the nineteenth century when post-Industrial Revolution population density in cities led to pollution and disease, it now approaches the nonsensical as housing developments are built miles from schools, work places and retail services, necessitating a greater and greater proportion of time spent in vehicles.

In Europe, where automobile ownership and maintenance costs twice what it costs in the U.S., cars are getting smaller, one researcher noted, while Americans are turning to larger and larger vehicles to accommodate the increasing time spent on the road.

The extreme auto dependency of America has serious public health consequences, Rutger's Pucher told the audience over a phone link from that New Jersey university. Besides lack of exercise and obesity, it contributes to pollution, social isolation, mental and physical diseases, depression, and traffic accidents, as well as physical conditions linked to inactivity such as atherosclerosis, asthma, diabetes and hypertension. The focus should be on how we can make walking and cycling part of America's everyday daily routine.

Conference presenters acknowledged that there has been much good design developed for walking and jogging parks and rail trails in America over recent decades, but noted that such developments were geared to leisure time activity disproportionately enjoyed by the young, fit, white and relatively affluent. To bolster health, they urged, opportunities for walking and cycling must be convenient, safe and cheap for all members of the population.

Increased walking and cycling in Germany and the Netherlands, in contrast, has been designed by the urban planners and governments of those countries to be integrated into daily living activities. Harvard School of Public Health professor Anne Lusk, who organized the conference with Dr. Walter Willet, chairman of the school s department of nutrition, highlighted the difference between American bikers and their Dutch counterparts with two slides. The Americans are road warriors shown on 10 speeds with hand brakes, she noted, accoutered in helmets, spandex jumpsuits, and toe clips. By contrast, the contemporary Dutch school kids are pictured on gearless bikes with coaster brakes like the ones we rode in the 1950s. (Boston, she said privately, has been characterized as the worst bicycling city in the nation, way behind other bike friendly burgs like Portland, Seattle, Pittsburgh, and Denver.)

The difference, of course, is danger. Cyclists are nearly twenty times more likely to die in an accident on a U.S. road than on a Dutch one. And therein lies the dilemma. You have to get more people (walking and biking) on the streets to make the streets safer, but in order to get more people on the streets, you ve got to make the streets safer, explained Ben Hamilton-Baillie, an architect and urban planner from Britain.

In Germany and the Netherlands, where pedestrian and cyclist accident rates are low, non-vehicular use of the streets is supported by public policy including land use zoning, traffic calming techniques, roadway restrictions and enforcement, as well as vigorous public education. All German children, for instance, have received education on pedestrian and bike safety regulations by the time they are ten years old. German drivers training manuals, unlike their U.S. counterparts, hammer at the rights of pedestrians and cyclists. In accidents involving a pedestrian and a motorist, the motorist is presumed to be equally at fault. If the injured pedestrian is a child or a senior citizen, the motorist must take the blame, even if the victim was jaywalking.

Design interventions conducive to safer and more enjoyable walking and cycling include wider, well-lit and well-maintained sidewalks; well-marked pedestrian activated crosswalks at each intersection and mid-block; closely planted trees and street furniture to convey a sense of place; lane reductions or road diets to slow traffic and allow more room for walkers, cyclists, wheelchairs and baby carriages; and pedestrian islands and reduced vehicular speed. In large parts of Germany and Sweden, for example, vehicular speeds in residential communities have been reduced to 30 km, or 19 mph.

The design know-how to create walkable, bikable cities already exists on both sides of the ocean, according to Alan Kreiger, chair of urban planning and design at Harvard; the trick is lassoing the political will to change.

Failure to build exercise into the daily American routine has particular implications for our youth, our elderly, and our poor. Attitudes towards exercise are conditioned in childhood, several speakers pointed out, and right now the picture isn't a pretty one. Between the years 1977 and 1995, the number of walking and biking trips made by U.S. kids between the ages of five and fifteen plunged 40 percent, according to a Centers for Disease Control study. More than half these kids said the chief barrier to walking or biking was the distance involved.

Single-use land development: school here, houses here, malls over there -- all the rage for the last fifty years, has resulted in a nasty loss of physical activity by kids, complained Howard Franklin, M.D., chairman of environmental and occupational health at Rollins School of Public Health, Emory University. Wide roads, Franklin said, engineer walking out of the equation while absent sidewalks, broken and obstructed sidewalks, send the signal that walking is not valued.

Steve Gortmaker, director of the Harvard Prevention Research Center, studied the activities of 139 seventh and eighth graders from the towns of Lynn, Framingham, Somerville and Cambridge, MA, in order to determine their levels of physical activity. To his surprise, he found that the kids, who were fitted with monitors, were more active on school days than on weekends and that their highest level of daily activity was on the way to school and immediately after school, on the way home or to an after-school activity. To encourage more kids to walk or bike to school, Gortmaker called for engineering and traffic calming changes which give pedestrians and cyclists the protections normally reserved for vehicles, and tough enforcement of laws protecting walkers and bikers.

Pedestrian and bike education must begin young, Gortmaker emphasized, with programs like Safe Routes to School, organized locally by WalkBoston. A lot of parents of very young kids will drive them to school because they are very, very young and they are not safe walking alone. But then, when the kids get older, they expect to be driven to school. They are already conditioned.

Don Eunson, the assistant director of the Safe Routes to School program, trains school administrators, parents and children about safe routes to school and educates the children about safe walking and crossing practices. For very young children like kindergartners, he said, Safe Routes to School has devised walking school buses in which children and supervisory adults snake along as one unit, a la conga line.

The interventions or influences that will push a child towards or away from physical activity worry Dr. Judy Ann Bigby, a physician who focuses on health care of low income and minority women at Brigham & Women's Hospital. Bigby, who is the personal physician to Boston Mayor Thomas M. Menino, noted that the U.S. now has whole generations of people who have grown up without so-called primary experiences of physical activity -- personally walking or biking to school, to stores, to work. Secondary influences, the impressions made on a child by seeing important adults or peers engaged in daily walking or biking, are effective but equally rare in our contemporary society. Verbal persuasion, such as a one-on-one conversation with a doctor urging daily physical activity, can be powerful, Bigby noted, but it has more clout if it dovetails with modeling by others and habit.

Bigby underscored the importance of influencing children to be physically active at an early age. She cited research that modeling behavior of the mother, grandmother, or other female family member has a particularly strong influence on children in the African-American community, much more so than that of the father. From an activity standpoint, this is not a good thing since communities of color have a large population of middle aged urban dwellers with high rates of depression and isolation.

Ted Landsmark, president of the Boston Architectural Center, characterized the mature, urban, African-American woman as the canary in the coal mine whose success as a cyclist would signal that urban planners and policy makers are finally getting serious about building regular cycling and walking into their transportation models. What would it take to get a black woman to ride a bike? asked Landsmark. I haven't seen that in 25 years.

Landsmark, who is black, asked ten female friends and found that only his white friends biked outdoors. All the black women, despite voicing health concerns directly related to exercise, cited inconvenient apartment living, auto packed urban streets, storage issues, fear of male harassment, and the lack of companions as reasons to avoid cycling. How do we get Oprah or Beyonce to promote biking? How do we change the attitude that biking is unstylish? Landmark asked; I submit to you that is more important than building a bike route from Jamaica Plain to Boston.