WEST LAFAYETTE, Ind. – The nation’s aging, overweight population is fueling demand for personal trainers skilled at prodding the out-of-shape of all ages to get fit.

But there’s no guarantee those buff trainers know the best workout for a 65-year-old man with heart disease or an obese woman in her 50s with diabetes.

Virtually anyone can become a certified trainer because there are no national educational standards for the field. Numerous Web sites offer personal trainer certification after just a few hours of online training – and a few hundred dollars.

That situation galls personal trainers such as Ken Baldwin, who has seen people become disillusioned or injured by working with unqualified trainers.

The Purdue University instructor helped create that school’s four-year undergraduate personal fitness trainer degree, which he believes is the first of its kind in the nation. The year-old program is built on Purdue’s health and fitness major, which already focused on exercise physiology, basic health studies, fitness evaluation and program management, psychology and nutrition.

“Large or medium-sized health club chains can’t grow because they don’t have good, qualified individuals to manage and oversee growth. There’s just a dire need for that,” said Baldwin, who oversees personal fitness training at Purdue’s Department of Health and Kinesiology.

The program has enrolled 30 students who learn the nuances of toning muscle groups and proper exercise movements, and get hands-on experience with cardiac rehab patients and people in physical therapy after injuries or surgery.

Students also work with seniors and children in fitness settings and take business and management courses so they can manage fitness clubs.

Sarah Hession, a junior from Indianapolis, originally planned to major in engineering but ditched it for a career engineering finely tuned bodies.

“It just felt right for me, the idea of helping other people get in shape, because it’s so important,” said Hession, 20, who hopes to open her own gym someday.

Purdue’s program is part of a national push to turn out better-educated personal trainers.

Mike Clark, CEO of the National Academy of Sports Medicine in Calabasas, Calif., said the nation’s aging population and the rise in obesity, diabetes, heart disease and other illnesses is driving the need for more sophisticated trainers.

Within a few years, he predicted, the standard for personal fitness trainers will be a bachelor’s degree and certification from an accredited organization.

“Personal training used to be the best-looking man or woman in the gym who’d try to teach you to get in shape. That sort of thing worked fine helping someone who’s already lean get in shape, but it’s another thing if your 65-year-old mother with cardiovascular problems goes to a gym and wants to get fit,” Clark said.

Clark’s group, which certifies about 10,000 people a year, began offering a fully accredited personal training undergraduate degree online this summer through California University of Pennsylvania. It also offers an online master’s degree.

He said the online programs are based on models that have taken 20 years to develop and aren’t like the “fly-by-night” certification programs rampant on the Internet.

Out of roughly 275 certification programs in the fitness world, he said, only four are certified by a third-party accreditation organization.

Marjorie Albohm, a board member of the Dallas-based National Athletic Trainers’ Association, urged consumers to ask about a personal trainer’s qualifications before they join a health club.

“We spend weeks shopping for a new car, but we walk into a gym and say, ‘I want someone to train me,’ and we don’t ask what their credentials are,” she said. “You’re trusting this person with your body – the most valuable piece of property that you own.”