When do you become a senior citizen?
That's an increasingly important question in Japan, the world's oldest nation, where the challenge is to keep people healthy and productive as they live longer.
The answer should be 75, ten years older than many people think now, according two groups of medical experts who specialise in ageing.
People aged 65-74 ought to be thought of as "pre-old," the Japan Gerontological Society and the Japan Geriatrics Society said in a report last month.
"Old" would be better defined as 75-89, and a special label of "super-old" could be adopted for people 90 and above, they said.
While these experts approached the subject chiefly from a medical viewpoint, applying theses definitions to the labour force could have profound economic implications for the nation, boosting the number of potential workers by more than 10 million.
Thanks to better nutrition, health care and sanitation, today's senior citizens are much fitter than past generations, and labelling them as retirees is a waste, said Yasuyoshi Ouchi, one of the architects of the report.
"There are many people who are older than 65 and are healthy and energetic," said Ouchi, who himself is spry at 68. "They are willing to contribute to the society by working, whether paid or unpaid."
A government survey of nearly 4000 people age 60 and over found that 51 per cent didn't consider themselves senior citizens. Most said that the label should be for people 70 and older.
Faced with a shrinking labour force and rising welfare costs, Japan's government is gradually raising the starting age for receiving pension payments from 60 to 65.
Ouchi, a medical doctor who is president of Toranomon Hospital in Tokyo, said it wasn't his intention to provide political cover for delaying pensions.
The aim of working longer is to stay active and healthy, and to contain soaring medical costs while lightening the burden on younger generations, he said.
Do you agree? Or are there more pressing issues?
Written Yoshiaki Nohara. First appeared on Stuff.co.nz.