Slumping in front of the television or a computer for hours at a time may damage important back muscles, according to scientists.
Australian researchers studied a group of 19 young men who spent eight weeks in bed.
They found that the lack of movement weakened the muscles that support and protect the spine, New Scientist magazine reported.
The researchers said that hours sat at a computer could have the same effect.
The researchers said the pain was as bad as having a physical injury.
Previous studies have shown that in most cases of lower back pain, the muscles that keep the vertebrae in place, or those that hold the pelvis together, are inactive.
In some cases, both sets of muscles are not working.
In about 15% of cases, this is caused by heavy lifting, whiplash or other injuries that damage these support muscles.
clipped from: news.bbc.co.uk 