Yoga for seniors can help with balance, agility and strength. But injuries do happen.

The elegant, silver-haired woman poked her head tentatively into my classroom as students were setting up their mats and chairs for a “gentle yoga” class. “Is it okay if I just watch?” she asked, then told me she had tried a yoga class to ease pain in her neck and back, only to find that actually made her problem worse.

It’s a complaint I’ve heard many times, particularly from older adults: that the supposedly healing practice of yoga caused pain. As a teacher specializing in therapeutic yoga for seniors and people with health challenges, I often work with those who have had a negative experience in a yoga class, frequently because it was an inappropriate style or level for the participant or was taught by an inexperienced or poorly trained instructor.

“Teaching yoga at a senior center is an entry-level job in many communities, which means they’re putting the least-trained people with the hardest crowd,” says Gale A. Greendale, a professor of medicine and gerontology at the David Geffen School of Medicine at UCLA. “There’s often a cacophony of preexisting conditions in this age group, and a yoga teacher has to be very skilled to not get older adults into trouble.”

With studies suggesting that yoga may be helpful in reducing heart rate and blood pressure, relieving anxiety and depression, and easing back pain, studios are filling up with baby boomers and older adults. Yet, seniors pose a special challenge for yoga instructors, because of their very mix of abilities and condition: Some 80-year-olds are still running marathons, and some 70-year-olds are unable to get up out of a chair.

“In general, older adults have less joint range of motion, less strength and poorer balance than younger men and women,” Greendale notes. “They also have more limiting musculoskeletal conditions, such as osteoarthritis and low back conditions, that may put them at higher risk of musculoskeletal side effects from yoga.”

Greendale first recognized this phenomenon when she led a study to assess whether yoga could decrease hyperkyphosis, an exaggerated curve of the thoracic spine sometimes called dowager’s hump. Her research, published in 2009, found that yoga improved the condition. However, during the six-month study, approximately 60 percent of the 120 participants — ambulatory people ages 60 to 90 — developed musculoskeletal soreness and/or pain significant enough to require modifications of their poses. Also, those with preexisting musculoskeletal conditions who hadn’t been bothered by those conditions were particularly likely to experience significant muscle or joint side effects.

“Most study participants had preexisting conditions in their hips, back, knees or shoulders that were quiescent until we started putting them through yoga poses — and we were already using versions of poses that were adapted in ways that we thought would be safer for seniors,” she recalls. “Even in robust seniors, the musculoskeletal risks were there, lying dormant until we woke them up.”

Like any physical activity, yoga has risks, Greendale says, but “I believe yoga’s benefits outweigh its risks as long as people start at the right level, don’t progress too fast and make appropriate modifications.”

One of the greatest risks of yoga for seniors may occur among those with compromised bone, since some common postures — such as straight-legged forward bends and end-range twists — can increase the risk of vertebral fractures, says Matthew Taylor, director of the Dynamic Systems Rehabilitation Clinic in Scottsdale, Ariz. “People with osteoporosis should work individually with a yoga instructor who has specialized training until cleared to safely participate in an appropriate group class,” says Taylor, past president of the International Association of Yoga Therapists.

Proper alignment is critical, notes Taylor, whose “Safe Yoga for Bone Health” webinar handout is offered on the National Osteoporosis Foundation’s Web site.

Safely practiced, yoga can be extremely helpful for older adults since “age and gravity are the tartar of our skeletal system,” he says. “Yoga is like postural dental floss. Just as we brush our teeth twice a day, we should do two, five-minute yoga practices a day. It doesn’t take a lot — just a few minutes to slow down, turn inward and move with attention.” This simple practice can help seniors learn — and be able to maintain — good posture, he says, which can enhance comfort, balance, respiratory function and mood.

For those interested in taking a yoga class, a good first step toward avoiding problems is to watch the yoga class and make sure the pace and moves being taught seem appropriate to your physical condition. Consider also whether the instructor explains the moves well and creates a non-competitive environment where students are encouraged to challenge themselves without straining. Be sure to start where you are — not where you think you should be — and if a move hurts, back off the pose. Talk with your teacher about modifications, and be honest and patient.

With the right class and instructor, you are likely to feel more relaxed and energized after your first class. Over time, you may experience enhanced strength, flexibility and balance. But pushing yourself to do too much, too soon can be a setup for injury.

The silver-haired woman who watched my gentle yoga class is now a regular participant and credits yoga with relieving her neck pain, easing chronic headaches and enhancing her sleep.

“The biggest surprise to me was the relaxation effect,” she says. “I had no idea how much tension I was holding in my upper back and shoulders, and yoga has helped me let go of my tendency to grip. Learning how to relax and breathe has made a huge difference in my life.”

Krucoff is co-director of the therapeutic yoga for seniors teacher training program offered by Duke Integrative Medicine and author of “Yoga Sparks: 108 Easy Practices for Stress Relief in a Minute or Less.”