Ohio residents Olga Stavridis, 53, left, and her daughter Maria Stavridis, 21, right, work out in a garage with personal trainer Caitlin Kennelly, who has a doctorate in physical therapy.

If you’re considering hiring a personal trainer in the new year, the coronavirus needn’t be an obstacle. Many trainers are offering virtual services; the only requirements to book a session are a WiFi connection and a way to pay digitally.

But there is one problem: “Anyone can say they’re a personal trainer,” says Francis Neric, the national director of certification for the American College of Sports Medicine (ACSM).

Even the title “certified personal trainer” isn’t necessarily a stamp of quality. According to Tyler Read, founder of PTPioneer, a website that helps aspiring personal trainers determine which certification to obtain, requirements vary widely among the approximately 30 organizations that offer personal trainer certification. One group says aspiring trainers pass its exam with as little as one week of preparation.

In an effort to create common professional standards, the International Health, Racquet & Sportsclub Association adopted a resolution in 2005 recommending that gyms hire only personal trainers who have completed programs that have been certified by a third-party accrediting organization, such as the National Commission for Certifying Agencies (NCCA), the Distance Education Accrediting Commission and American National Standards Institute. But, as with training programs, each third-party accrediting body has its own standards.

Thus, the personal training profession remains a “Wild West,” says Stephanie Cooper, assistant professor of kinesiology at the University of San Francisco and certified exercise physiologist.

Neric says the “alphabet soup” of credentials and certifying organizations can confuse consumers and leave them vulnerable to underqualified trainers. More than half a dozen fitness industry experts interviewed for this article named the National Academy of Sports Medicine as one of the most well respected certifications in the industry.

At best, working with an ill-educated trainer is a waste of time and money. At worst, it can lead to injury, says physical therapist Theresa Marko. According to Marko, owner of Marko Physical Therapy in New York, trainers are best for people who are already healthy and who want to be more fit. Although trainers have the skills to notice poor form, they’re “not trained on how to eliminate the biomechanical dysfunction” causing it, she says. Ideally, when clients have a limited range of motion or experience pain, their trainer should refer them to physical therapy, and the two providers should then collaborate.

So how do you know whether your trainer has the skills to help you meet your fitness goals safely? Here’s what to look for, as well as red flags to avoid:

Good signs

Our experts emphasized the importance of finding a trainer with an NCCA-accredited certification, relevant experience and education, and someone with whom you feel comfortable.

Given the dizzying number of certifications, it’s hard to know which ones are high quality. According to Neric, any certification from an NCCA-accredited organization is a safe bet. Read, who has researched many programs and has obtained multiple certifications, says the NCCA is the “gold standard,” because of the rigor required to obtain its recognition; organizations much prove their programs do not “teach to the test” and must require continuing education.

Non-NCCA-accredited programs are not necessarily held to the same standards. For example, one such program gives certificants who do their training online up to two months to complete their exam and no limit on the number of times they can stop and start the test.

Sarah Johnson, association director of group exercise at the YMCA of Metropolitan Washington, tends to hire personal trainers with credentials from NCCA-accredited groups. Both she and Read say the American Council on Exercise, American College of Sports Medicine, National Academy of Sports Medicine, National Council on Strength and Fitness, and National Strength and Conditioning Association are the most reputable organizations, having consistently remained on the NCCA list. Trainers will typically include their certification in their website bios or on their social media accounts.

Do your own vetting, even if you hire a trainer from your gym, says Shannon Fable, a fitness business consultant and American Council on Exercise emeritus board member. “You cannot make the assumption that just because someone is still raking in the clients and making money that they’re certified.” To find out whether your trainer’s credentials are up to date, search the US Reps database or the website of the certifying organization.

Certification is a good start. But even credentials from a well respected authority demonstrate only that a trainer has met “a minimum threshold to be safe and effective,” Neric says.

Ask potential trainers whether they’ve worked with people of your age and level of physical fitness, and whether they have an additional certification or relevant degree in a field such as physical therapy, occupational therapy, exercise physiology or kinesiology.

At the YMCA, Johnson avoids pairing new personal trainers with clients who have complicated medical histories. According to Lauren Korzan, regional program manager for a corporate wellness consultancy and an ACSM-certified exercise physiologist, anyone with an injury or chronic health issues such as heart disease, diabetes or an orthopedic condition should find a trainer with both relevant coursework and experience.

For example, if you take a beta blocker for hypertension and your trainer gives you a fitness assessment, that person needs to understand that the medication limits your ability to elevate your heart rate. Otherwise, Korzan says, “you keep pushing, pushing, pushing to get that heart rate to a certain number,” and you may never get there, potentially creating a “really dangerous” situation.

On the other end of the spectrum, people with high-level, sport-specific goals also should choose a trainer strategically. Cooper suggests that military personnel and first responders find trainers holding credentials such as tactical strength and conditioning facilitator. Similarly, Neric says, runners wanting to shave time off their marathon should find trainers who work with endurance athletes and who have completed relevant continuing education.

The best education and experience are no substitutes for a good relationship. “A lot of it comes down to trust,” Neric says.

Find someone you feel comfortable being “100 percent honest with,” Johnson says. Failing to tell your trainer about post-workout soreness or fatigue can hurt you if your trainer advances your programming based on a false understanding.

Your personal trainer should empower you, Fable says, and “shouldn’t just be wowing you with their six-pack abs and their craziest movements. They should be wowing you with the way that they make you feel.” Find someone who will help you become a “lifelong mover.”

Red flags

Even if it looks like someone has the right certification, experience and philosophy, there are still red flags to watch out for. If your trainer exhibits these behaviors, that person may not be right for you:

‘No pain, no gain’ mentality. “You don’t have to not be able to walk the next day for [training] to be effective,” Johnson says. Neric concurs; when he sees people doing “crazy things,” such as jumping from one stability ball to another, he wonders why. Most of the time, he says, the high risk of injury isn’t worth the potential reward.

Additionally, pain is an important signal, says Marko, the physical therapist. She suggests stopping any activity that induces a sharp, stabbing pain; tingling that radiates down your leg; or back spasms, regardless of your trainer’s directives.

Overpromising. Neric says promises of dramatic weight loss are “a complete red flag.” Fable agrees. “Before and after” pictures are “great marketing tools,” she says, but “there is no perfect program that is going to make you drop x-y-z pounds or inches in the next six weeks.” And if trainers promise you that their exercise programs will make a huge difference in your physique? “They’re lying,” Fable says.

Selling products. Cooper would be leery of any trainer selling nutritional supplements, which many do through multilevel marketing companies. Not only is this a conflict of interest, she says, but prescribing supplements and nutrition plans is also outside of a personal trainer’s scope of practice. Fable adds that even trainers who hold the appropriate degree or certification to legitimately recommend diet and supplement advice shouldn’t be “pushing [products] on you to get results.”

A good personal trainer always has your best interests in mind. To optimize your chances of reaching your goals and avoiding injury or burnout, look for someone with an NCCA-accredited certification, relevant experience and continuing education, and someone who will refer you to physical therapy or a dietitian if needed.

Also, make sure you have chemistry with your potential trainer. Because, as Fable points out, personal training is both “an art and a science.”

Moore is a Boulder, Colo.-based freelance writer, speaker, marathoner, Ironman triathlete and certified personal trainer.