A good way to find a personal trainer is to ask someone you trust -- a friend, relative, coworker, or health care provider. And if you are considering a particular trainer, don't be shy about getting references. Though some gyms give some free initial lessons, personal trainers don't come cheap: Sessions range from about $50 to well more than $100 in some areas.

Here's what to ask a potential personal trainer before picking up the dumbbells:

1) What is your educational and training background, and are you certified? Whether employed at fitness and health club facilities or in private practice, personal trainers in the U.S. often have a fitness-related bachelor's degree and some sort of certification. But more than 100 different organizations certify personal trainers, and there are no national standards. The level of knowledge needed to get certified varies widely among the organizations -- from having a degree in exercise physiology and passing a comprehensive exam to simply laying out the cash and taking an online open-book test. According to a survey of trainers, done by researchers at Brown University and published in Orthopedic Reviews in 2016, "personal trainer fitness related knowledge improves with a bachelor's degree and a more rigorous certification."

2) What organization is the certification from? Among the most respected certifying organizations are the American College of Sports Medicine (ACSM) and the National Strength and Conditioning Association (NSCA), which require personal trainers to pass an extensive exam, maintain continuing education credits once certified, and be certified in CPR. While many certifications, like NSCA, require a bachelor's degree, others like ACSM and the American Council on Exercise (ACE) require only a high school diploma or equivalency certificate; some have no education prerequisites at all. Whatever certification the trainer has, it should be accredited by a third-party agency, such as the National Commission for Certifying Agencies (NCCA, which is the most reputable) or the Distance Education Accrediting Commision (DEAC).

3) Do you have a specialty area? Does the trainer mostly work with hardcore athletes (such as marathoners and bodybuilders), seniors, pregnant women, or people with biomechanical issues (such as knee and back problems)? If you have a medical condition that can affect your ability to exercise safely, such as osteoporosis, severe scoliosis, asthma, or a prior heart attack, make sure to tell the trainer and find out if he or she has experience in that area. Some certifying organizations give trainers the opportunity to attain a specialty certification or more education in a specialty area. For example, an ACSM trainer may become a "Certified Cancer Exercise Trainer," while under ACE, a trainer may be further trained in such areas as fitness nutrition, senior fitness, and sports conditioning (which focuses on building speed, agility, balance, and strength).

4) How long have you been a trainer? Look for a trainer who has at least a couple of years of hands-on experience (or at least someone not brand new to the job). But other important factors to consider are if the trainer communicates well, is supportive and motivating, suits your personality, and can help you meet your fitness goals.

Final note: Personal trainers are sometimes confused with athletic trainers, who specialize in the evaluation, prevention, and rehabilitation of acute and chronic injuries and illnesses, and often provide emergency care at sports events. Working in health care settings or with sports teams (and not typically at gyms), athletic trainers have a minimum of a bachelor's degree (though master's degrees are common) and are certified through the national Board of Certification, a nonprofit credentialing agency established for this profession. In all states except California, athletic trainers must also be licensed.