Middle age also starts later; a 60-year-old is now middle-aged, experts said

, women are 'old' at 73 and men at 70

aren't old until they are within 10 to 15 years of dying, scientists say

Retirement may be beckoning and your knees may be creaking. But if you are 60, you are merely middle-aged.

Scientists say that as we live longer, we need to rethink what we classify as being old.

They say that rather saying old age starts at a fixed age such as 60 or 65, we must factor in how much longer we have to live.

They suggest that we don’t think of ourselves as being old until we are within 10 to 15 years of the average life expectancy for our countrymen and women.

We need to reclassify what we think of as being old, Austrian scientists have declared in a new study. People shouldn't think of themselves as elderly until they are within 10 to 15 years of dying

The average life expectancy for women in the UK is 82.8 years, meaning British females needn't consider themselves old until they are 72 or 73.

Similarly, with male life expectancy at 79 years, men don't become old until they are close to 70.

And if old age starts later, by definition, middle-age does too.

Researcher Dr Sergei Scherbov, said: ‘Age can be measured as the time already lived or it can be adjusted taking into account the time left to live.

‘What we think of as old has changed over time and it will need to continue changing in the future, as people live longer, healthier lives.

‘Someone who is 60 years old today, I would argue is middle-aged.

‘Two hundred years ago, a 60-year-old would be a very old person.’

He has previously shown that many people who are classified as old are as strong as younger people.

For instance, highly-educated 65-year-old Americans had the grip strength of 60-year-olds with less education.

Dr Scherbov, of the International Institute for Applied Systems Analysis in Austria, said: ‘In terms of their physical strength, they are five years younger.’

Based on average life expectancy, men are now not 'old' until they are 70 and women aren't elderly until 73

In his latest study, which was funded by the European Research Council, he calculates that if we fix old age at a certain point, the proportion of old people will increase with increasing life expectancy.

But, if move the threshold for being old to take into account longer lives, the proportion of old people actually falls over time.

He added that modern medicine, education and improvements in sanitation, living conditions, diet and lifestyle, have all helped increase life expectancy.

Writing in the journal PLOS ONE, he said understanding just when people become old is key to all sorts of economic calculations, including state pension age and healthcare costs.

Dr Scherbov, said: ‘Health care costs depend on age but they are much higher in the last years of life.

‘As life expectancy increases, those last years of life happen later and later.

‘Ignoring this could produce distorted figures.’