It is a familiar sight in the streets and alleys around office blocks - women slipping out of their stilettos and into their pumps or trainers for the walk home.
But they might be better off if they don't change their shoes at all, according to research.
Women who spend most of their time tottering around in high heels will cause muscle damage that makes it very uncomfortable to walk in flat shoes, scientists claim.
Discovery: Scientists have found that changing into flats from heels is not as sensible as one might think
This is because, over time, walking in heels causes calf muscles to become shorter and weaker. When the wearer switches to flats, the muscles are suddenly stretched into a position they are not used to, causing pain and discomfort.
Scientists at Manchester Metropolitan University found that women who wear heels five days a week over two years can shrink their calf muscles by up to 13 per cent.
They say this shortening effect can be permanent, and the only way to prevent it is by doing stretching exercises at the end of the day.
The researchers found that even women who wear relatively low 2in heels can suffer from long-term muscle damage.
2High risks: Changing shoes can lead to problems, according to scientists at Manchester Metropolitan University
High risks: Changing shoes can lead to problems, according to scientists at Manchester Metropolitan University
High heels effectively cause the wearer to walk on tiptoes, reducing the distance between their ankles and the backs of their knees.
To compensate, the calf muscles contract - and will usually stretch out again once the heels are taken off.
But if high shoes are worn for most of the day, for weeks on end, the muscles can shrink permanently and become weaker. As a result, when these women try to walk in flat shoes, their calves are forced to stretch out, causing pain and discomfort.
The study, published in the Journal of Experimental Biology, involved women who had worn heels at least 2in high on a regular basis during the previous two years.
It found that their calf muscles were, on average, 13 per cent shorter than those who stick to flats. Professor Marco Narici, who led the research, said: 'Women who wear heels fairly regularly will see a chronic effect on their calf muscles.
'They will become progressively shorter and will find it very difficult to stretch out again once these shoes are taken off and the woman tries to walk around normally.
'Often it will be very uncomfortable for a woman to wear trainers or even walk in bare feet.
'The muscles are not used to being stretched and people may experience pain in the backs of their legs.
'It doesn't take very long for this to happen - our research looked at people who had worn heels regularly for the last two years.'
But the researchers advised heel wearers that regular stretching exercises after removing the shoes can prevent calf muscles from shortening.
One recommendation involves placing the right foot on a step, and the left foot on the next step up. The right foot should be moved so that the heel hangs off the step, and lowered until the calf muscle feels stretched. This should be repeated several times on each side.
culled from Daily Mail UK