• Melton Truck Lines Inc. replaced sodas in the Tulsa, Okla., headquarters vending machines with green tea, water and diet drinks. The company also offered a 12-week weight-loss series.

• Con-way Freight of Ann Arbor, Mich., saw annual workers compensation claims plunge 80 percent and lost work days drop 75 percent in Los Angeles after its trial of a wellness program two years ago. Now leaders of such programs are being hired at other hub offices.

• Schneider National Inc. of Green Bay, Wis., screened 10,000 of its 15,000 drivers for apnea, a disorder that interferes with breathing during sleep and can leave the sufferer groggy and exhausted. The company provided the 10 percent who had the disorder with special air masks to help them sleep.

Some drivers are responding to all the health campaigns, working out at loading stations, cooking for themselves and even walking laps around their rigs. (Thirty-two times around an 18-wheeler is a mile.)

Sammy Belvin, a driver for Oklahoma-based Melton Truck Lines, has been getting advice from a wellness coordinator with the company. He carries weights in his truck, and for meals, he eats cereal and cooks chicken breasts on an electric grill in his cab.

A driver for 23 years, Belvin says these days he's not the only one jogging around in the mornings before he drives off for the day.

Lisa Miles, an independent driver based in Fort Wayne, Ind., lifts weights in the cabin of her semi, too, while her partner driver takes the wheel. She gave up smoking three years ago and now is trying to lose 30 pounds.

"It's real easy to let your personal health be the last of your priorities," she said.

As many as half of drivers are regular smokers, compared to about one-fifth of all Americans. Many truckers are obese, and only about one in 10 get regular aerobic exercise. More details will be available in a soon-to-be-published study for the Transportation Research Board, an arm of the National Academy of Sciences. All those bad habits can fuel high blood pressure and chronic conditions like heart disease and diabetes.

Sleep apnea, which is linked to obesity, is rampant too. An industry study a few years ago found 28 percent of drivers had it; that compares with about 4 percent in the general population who have the disorder.

Government numbers say the trucking industry has the most fatalities of all occupations. The Bureau of Labor Statistics says truck drivers account for nearly 15 percent of all worker deaths in the most recent data available, from 2005. (The death rate per 100,000 is higher for other occupations.) Of those trucker deaths, 80 percent involved traffic accidents, the bureau said.

Truck drivers also report more injuries, such as sprains, than workers in any other category, according to the Occupational Safety and Health Administration. Many of them unload the goods they carry, risking back injuries. Truckers pose unique challenges when it comes to improving health, said Ilene Masser, director of such a program for faculty and staff at New York University Medical Center. They sit for long periods, are out on their own, eat a lot of fast food and most of them are men, who often need more prodding than women to make changes, she said.

Changes are worth it. About three-quarters of employers with at least 1,000 workers have a wellness program, she said. And for every dollar invested, they get about $3.14 back, including savings on health-care costs and added productivity.