By Jane Elliott
Health reporter, BBC News
Flo's family say the classes have kept her active
Flo Harmsworth is a good example of the old adage, "It's never too late to get fit."
At the age of 90 her doctor prescribed exercise classes to help combat the painful effects of peripheral vascular disease - narrowing of the arteries.
Her legs were aching and, despite having a very active life, she was starting to find it too painful to walk.
Now a decade later the centenarian is still taking part in the Royal Free Hospital weekly classes and loving them.
Over the years she has done Scottish dancing, basic step and aerobics and is still doing gentle circuit training and step although, because of her increasing frailty, Flo now does part of the class from her chair.
But says she still loves it.
Flo, from north London, said: "It's no good sitting there and looking on, you have to do the exercises."
She said she also enjoys the social aspect of the classes.
"It is something to do."
Daughter Eve Murfin feels the classes have been a key factor in her mother reaching her century.
"It has helped her longevity. Everyone is amazed by the fact that she got to 100 and that she was in an exercise class.
"She was always very active. She has always done plenty of walking and she reckons this has kept her fit.
"She was the youngest of nine and she's a strong, fit woman. After my father died she even took up Outward Bound for the elderly," she said.
Flo has done gentle circuits and aerobics
The classes were set up by exercise nurse specialist, Tina Theothilus, and nursing sister Phyllida Morris-Vincent.
Tina helps to run two exercise programmes for patients with vascular disease attending the Royal Free. The hospital exercise programme involves 12 weeks of exercise classes aimed at 70 to 100-year-olds, and about 20 people attend each week.
She also runs a community programme for patients who have completed the 12-week hospital programme to ensure they continue to exercise and maintain good health.
The classes are mainly to treat peripheral vascular disease but many of the patients suffer from other problems such as osteoarthritis, painful joints and balancing problems.
The patients are told to "walk into the pain", to improve circulation in their legs.
They are also taught how to maintain balance and strength by doing basic exercises, usually holding onto the back of a chair or doing exercises sitting in a chair while listening to music.
Tina calls her patients once a week. "We keep phoning the patients to encourage them as the exercise is so agonising but they are so strong-minded," she said.
She said Flo, who is a good decade older than most of the other patients, is the definite star of the show.
"She has been amazing."
Tina said that when Flo, who now has additional health problems associated with poor circulation and coronary heart disease, first started exercising with the class she was encouraged to take a brisk 30-minute walk each day.
"She had a boyfriend at the time with a Zimmer frame who could not walk as fast as her though and she was always complaining that he could not keep up with her and how could she do her brisk walking," said Tina.
Age Concern's director general, Gordon Lishman, said it was vital the elderly kept as active as they can.
He said more than 90% of the over-75s failed to achieve the recommended level of at least half an hour of exercise five-times a week.
And he said 21% of those over 65 could not even walk 200m without discomfort or stopping.
Mr Lishman said classes, like those attended by Flo, would improve their health.
"It is incredibly important for older people to take regular exercise to stay fit and well in order to maintain their physical and mental health," he said.
"Exercise can help older people to stay mobile and independent, ensure a healthy heart, keep weight and stress levels under control, and promote better sleep.
"Short bursts of exercise don't have to be overly strenuous and can make a big difference to an older person's health.
"Exercise through social activities such as interactive games can also play an important role in maintaining the physical and mental wellbeing of older people.
"Despite the benefits, many older people still aren't exercising enough.
"We would urge any older person who is willing and able to exercise to find out what classes are available locally or introduce an easy activity, such as walking, into their lifestyle," he said.