BOSTON (MainStreet) — If you're trying to build abs that look like Matthew McConaughey's or a tummy as firm as Heidi Klum's, here's a look a five U.S. cities you definitely don't want to move to.

"These communities just don't have the [right] environment to support people who want to be physically fit," says Georgia State University's Walt Thompson, who oversees production of the annual American Fitness Index.

Compiled by the American College of Sports Medicine, the AFI grades the nation's 50 largest metro areas on a range of fitness factors, from obesity rates to how many residents walk or bike to work.

Thompson says cities with high AFI scores not only have healthy citizens, but also the infrastructure of parks, swimming pools and other facilities that help make physical fitness possible.

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But he says those who want to get or stay in shape should avoid communities with poor AFI rankings. "You won't find the kind of environment that's going to help you," Thompson says.

The American College of Sports Medicine prepared the year's rankings using data from the U.S. Centers for Disease Control and other public and private agencies.

Each community's score represents the average of how it ranked on all factors that researchers considered (a city would have to come in first place in every area to score a perfect 100).

All health statistics refer to residents of a given community's entire metro area, but figures on the prevalence of local fitness facilities (baseball fields, swimming pools, etc.) only refer to those within city limits.

The term "average" refers to averages among the 50 cities studied, while references to health problems "in the last 30 days" refer to issues that residents experienced within a month before talking to researchers.

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Here's a look at the five cities at the bottom of this year's AFI:

Fifth-least-fit city in America: Memphis, Tenn.
36 (out of a possible 100)

Perhaps it's no surprise that the city where a bloated Elvis Presley died has the highest obesity rate (33.6%) of any community that AFI researchers studied.

Memphis also has the highest death rate for cardiovascular disease and diabetes, and also comes in last place for the share of residents who reported engaging in any physical activity or exercise in the past 30 days.

In fact, Memphis scores below average for every personal-fitness factor considered except for asthma rates and the percent of people who experienced any physical or mental-health problems within the past 30 days.

The city likewise ranks below average on a per-capita basis for all local fitness facilities counted, except for golf courses.

Fourth-least-fit city in America: Louisville, Ky.

Located in the heart of tobacco country, Louisville has the highest smoking rate (28.1% of residents) of any metro area researchers analyzed.

Perhaps that's why the Derby City also has the second-highest angina/heart-disease rate — 5.4% of all citizens — of any community studied. In fact, Louisville scores below average on most personal-fitness measures the AFI includes.

Kentucky's largest city also rates poorly on almost all measures of fitness-friendly infrastructure. For instance, Louisville has just 0.8 swimming pools for every 100,000 residents — the fourth-lowest rate among America's largest cities.

Third-least-fit city in America: San Antonio

San Antonio rates below average on most personal-health gauges that AFI experts studied, coming close to last place in several categories.

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For example, the River City's 32.8% obesity rate is the fourth-worst showing among big U.S. cities.

San Antonio also scores poorly on virtually all measures of fitness infrastructure that the AFI reviewed. For instance, the city has some of the fewest parks and tennis courts on a per-capita basis of any large U.S. community.

Second-least-fit city in America: Detroit

Motor City residents might want to drive less and walk more, as they score below average on the vast majority of individual-fitness gauges that the AFI rankings include.

Detroit scores particularly badly when it comes to deaths from cardiovascular disease. Motown sees an estimated 240.7 such fatalities each year for every 100,000 residents — a rate second only to that of Memphis.

Detroit also has below average per-capita numbers for most of the physical-fitness facilities that researchers counted. For example, Michigan's most-populous city has no dog parks — one of only three major U.S. cities to lack them.

Least-fit city in America: Oklahoma City

Oklahoma's largest city has come in dead last in AFI rankings every year since researchers added the community in their study in 2009.

Residents fall well below average in every personal-fitness measure tracked, coming in last place for the percent of citizens who eat enough fruits and vegetables (15.8%) and those who take public transportation to work (0.5%).

Oklahoma City also has below-average per-capita levels of every type of fitness facility measured except for golf courses and acres of parkland. For instance, the community has just 0.6 baseball fields for every 10,000 residents — one of the lowest rates for any city studied.

Things are so bad that AFI experts met with Oklahoma City's mayor last year to recommend ways to improve local fitness. Researcher Walt Thompson says the city has adopted some suggestions, "but it takes a while for policy changes to take effect."

— By Jerry Kronenberg