10 Things Your Personal Trainer Won't Tell You

And yet not all so-called specialists are properly trained — on the fast-and-loose end of the spectrum, you'll find certification requirements as minimal as a $500 fee and passing an online exam. That worries John Buse, president of medicine and science at the American Diabetes Association, because when exercise isn't done properly, any vision problems and nerve damage in the feet that some diabetics develop could worsen, he says, in extreme cases to the point of blindness or amputation.

Given that 37% of health club members are beginners, personal trainers are largely catering to the unfit, according to IDEA Health & Fitness Association, a San Diego-based organization for fitness professionals. They're reaching out to seniors as well, since clients 55 years and older constitute one of the fastest-growing segments of gym members, says IDEA's executive director, Kathie Davis. Nonetheless, many trainers are guiding clients with a less-than-gentle hand. "The majority of people that come into the club haven't worked out since their high school gym class," Thomas says. "Then we're told to work them hard. It's dangerous." If you feel your trainer is being too tough, speak up. Remember, you're the boss.

This niche is growing because our kids are: Roughly 15% of American children are overweight, ranging from a high of 22.8% in Washington, D.C., to a low of 8.5% in Utah, according to nonprofit Trust for America's Health. But not all health clubs have trainers who work well with kids — or even know how to work them out safely, says Davis. Even a good trainer with the wrong attitude can turn impressionable kids off to working out.

Bottom line: Be selective. For starters, ask for a trainer with a background in teaching, coaching or child development, Davis says. And if your kid is involved in a particular sport, requesting a trainer with a similar background can help develop specific muscles and prevent injuries.

Though health clubs don't typically dangle the group option in front of you, most personal trainers will work something out if you ask. After all, it's a win-win situation. For a group of three, for example, the average fee of $60 per hour is reduced by half for each client, while the trainer brings in about 50% more than he typically makes in an hour. And it could mean a better workout: "There's a lot to benefit from group camaraderie, as long as you don't need a trainer counting every rep you do," says Richard Cotton, national director of certification for the American College of Sports Medicine.

"The best trainers serve clients by helping them become independent exercisers," Cotton says. He suggests asking prospective trainers how they'll help you get there. A spokesperson for the National Exercise Trainers Association says it encourages trainers to prove to clients there's more to working out than using big machines, in part because of the benefits of functional training.

Other health clubs are less stringent. Bally Total Fitness doesn't have a company-wide code of ethics by which trainers must abide, but says it's confident its trainers were adequately informed about general ethics during their individual certification programs. "Unfortunately, our industry does not have the same federal regulation as, say, a psychiatrist that risks losing a license if he shares personal information," Florez explains. Before divulging private health information to your health club, ensure that it has a strict privacy policy. And think twice before pouring your heart out to your trainer.

How to know what you're getting? Find a list of programs with third-party accreditation from the National Commission for Certifying Agencies at www.noca.org, an umbrella group that weeds out lesser training programs. Industry experts point to the American College of Sports Medicine and the National Strength and Conditioning Association as two of the most reputable organizations.

To find the right match, ask for a trial workout session with a trainer before you hire one. Florez specifically recommends a preliminary consultation, which should include no exercise but rather an in-depth conversation about your personality and goals. To evaluate a prospective trainer's ability to produce results, ask questions like, "Have you worked with someone like me before and been successful?" If the answer is yes, request a recommendation from that person.

The personal-training industry has high rates of employee turnover, partially because of low salaries, which average $32,900 for independent trainers and $35,000 for those employed by a health club, according to IDEA. Plus, the flexible nature of the gig attracts those who want to work part-time while following other pursuits, like acting or dance. Unfortunately for you, when your right-hand man lands a callback audition that conflicts with your next appointment, you're the one stuck rescheduling or settling for a sub. To help avoid future disappointment, ask about your prospective trainer's intentions and long-term career goals, especially if you're interested in purchasing a bigger package of sessions.

Not only that, but if you're facing certain health issues, nutritional advice given by trainers can sometimes do more harm than good. "Nutritional supplements, when mixed with other medication and strenuous exercise, can result in injury or even death," says a spokesperson for the American Council on Exercise. Take one of the country's growing epidemics — diabetes. For those suffering from it, "it's crucial that your health care provider knows you're taking nutritional supplements, because it can be dangerous," Albright says.

Buyer, beware: Before agreeing to alter or supplement your diet based on a trainer's recommendations, ask lots of questions, and keep your doctor in the loop, Albright advises. The best personal trainers don't pretend to be health professionals, but they are happy to facilitate an open channel of communication between a client and a health-care provider if the situation calls for it, says a spokesperson for New York Health & Racquet Club.