Just as Moya Waterworth was beginning to recover from her battle with cancer, she suffered a stroke – and with the stroke came epilepsy. Already physically and mentally spent from the cancer treatment, Moya wasn't sure she had it in her to keep going. "I think I would have gone under," she says.

That was 2½ years ago. Today, Moya (69) shows very few outward signs of having had a stroke and there is little evidence of the emotional struggle it triggered.

So what happened? During the cancer treatment, Moya had taken up the ancient Chinese martial art of tai chi. The surgery to remove the cancer had left her in terrible pain and the strong pain medication she was using was causing her to hallucinate, making it impossible to get back to her life. At the pain clinic, one of the nurses recommended combining a less powerful painkiller, with tai chi, as an alternative way to manage the pain.

Moya could not find a suitable class locally. She tried a class that was very much martial-arts based, with “energised” men with weapons, but gained little from it. So she bought an instructional DVD.

“I found it very relaxing,” she says, “but I can’t say that I immediately found any difference with the pain. But it was a distraction and I was able to concentrate on something other than the pain.”

Later, Moya joined a class run by Suzanne Vaughan, a former occupational therapist who was now teaching tai chi. After only a few weeks, Moya found that she would forget about the pain during the class. "Later, in the afternoon, I became aware of it again, but the penny dropped that this really, really would help if I could do it more frequently."

Moya began to practise daily. Following the stroke, she turned to tai chi again and, although it hasn’t “cured” her, Moya believes it has helped with her recovery. “I’m not going to get 100 per cent better – and I’m not going to pretend that’s what happens – but in my case, tai chi has certainly helped. It has helped me recover my movements and co-ordination and to become better. I can walk perfectly well and I can run.”

Moya’s recovery is not unique. There are others in her tai chi class – and tai chi classes around the world – with similar tales of tai chi assisted recovery from illness. Alongside the anecdotal evidence, there is also growing scientific evidence that tai chi, which began as a form of self-defence, is a great way for the over-65s to recover from illness.

It is hard to accurately describe tai chi. Stuart Hudson, who attends the same class as Moya, jokes that "it's like kung fu, but in mega slow motion". However, according to instructor Suzanne Vaughan, "if you combine elements of yoga with elements of Pilates, and you add that to mindfulness, you're getting close to what tai chi is about."

While that may sound like a strange mix, the unique combination of slow, choreographed movements, controlled breathing and meditation can provide all manner of health benefits.

A 2013 study by the University of Arizona College of Nursing found that Yang-style tai chi could improve balance, strength, flexibility and aerobic endurance in stroke survivors, significantly reducing the risk of falls.

In a pooled analysis of 21 studies, published in the British Journal of Sports Medicine in 2015, it was found to improve the physical capacity and muscle strength in older adults with breast cancer, heart failure, osteoarthritis and COPD. Importantly, these improvements were provided without causing additional pain or breathlessness. In those older adults with COPD, tai chi reduced breathlessness.

At Griffith University in Brisbane, Australia, researchers developed a simplified form for wheelchair users. When elderly residents at a long-term care facility practised this tai chi, it improved their physical and mental health. At China’s Fujian University of Traditional Chinese Medicine, researchers have found evidence that it can provide some protection from age-related cognitive decline.

Part of the appeal is that there is no such thing as too old – or too out of shape. It is a low-impact exercise that anyone – regardless of age or ability – should be able to do. However, there have been a number of efforts to develop tai chi styles for older adults who may have experienced some reduction in their physical or mental abilities.

The Department of Nursing at Fooyin University, Taiwan, for example, developed the “Simplified Tai Chi Exercise Program (Step) for frail older adults”. Step, which has fewer leg movements and knee bends and less complicated hand gestures, is designed to be less challenging, physically and cognitively.

Vaughan believes that the traditional tai chi style she teaches is suitable for most people. “I teach Yang-style,” she says. “ Having tried various styles, this is the one that I think is the most suitable for everyone and that’s why I teach it. It has very rounded movements, so it’s particularly good if you’ve got problems with your joints. You can even do it seated or lying down.”

In addition to stroke survivors, Vaughan has taught tai chi to people with head injuries, fibromyalgia, osteoporosis, arthritis and multiple sclerosis. “If you’ve got a good teacher, a good teacher will be able to adapt any movement to what you can do,” she says.

You don’t have to be ill to enjoy the benefits, though. It has been found to be a good way to stay healthy, maintain mobility and keep the brain active.

One of the class participants is Laura, who practises to keep fit and flexible – and it’s working. At 88, Laura can still do a high kick.

Sally is 74 and is the main carer for her sister, who has dementia. She uses tai chi to help her cope with the demands of being a carer.

Marie finds tai chi an enjoyable way to relax, but she also believes it’s improving her memory and co-ordination.

Stuart, who started when recovering from a stroke, says the social side has given him back the “camaraderie” he enjoyed as a soldier.

Although tai chi may offer many health benefits, it is not a cure for anything. While it has helped Moya in her recovery, she accepts that there are some things she can’t fix. She may never get back to how she was before the stroke, but, physically and mentally, tai chi has brought her far.

“I can’t speak highly enough about it,” she says. “There are so many benefits, I could go on for hours. People should give it a chance – and stick with it for at least six weeks.” She does, however, have a warning.

“Pick your class carefully, because you could make the mistake I made of going to a martial arts tai chi class. While it was fascinating to watch a whole room of men swinging swords without anybody getting hurt, it wasn’t for me.”