First it was texter's thumb, closely followed by Blackberry cramp.

Now health experts have issued a warning about the latest in the long list of hi-tech ailments … iPod finger.

The problem, they say, is that users of the wheel-driven music player are changing songs too often.

By constantly clicking on and rotating the iPod's central control, used to select a song from the thousands that can be held, users run the risk of permanent hand damage.

"This is a really serious problem," said Carl Irwin of the British Chiropractic Association. "The action needed to move the wheel on an iPod is totally unnatural and effectively separates the joint in the thumb every time you use it.

"This causes inflammation in the thumb or fingers and can be very painful. We have also seen cases of iPod users where the problem has spread to their elbow and neck.

"Once you have problems with the thumb or fingers, the whole of your posture can be affected as a result."

Only a few cases have been reported in his Ealing practice so far, Irwin says. But he expects to see a lot more as people who have simply been putting up with what they thought were temporary problems seek medical advice.

"In the next six months I expect to see a big rise in the number of people with Repetitive Strain Injury-like symptoms from using these gadgets," he said. "The condition can be extremely painful."

Irwin said he is particularly worried about children using iPods for long periods, as their joints are still growing and extended usage could cause "problems they will not see until early adulthood".

Irwin called for Apple and other manufacturers to take RSI into account when designing devices.

But Apple, which has sold over 27 million iPods worldwide, refused to comment on the warning, backed up by the views of some American experts.

"Handheld electronics may require prolonged grips, repetitive motion on small buttons and awkward wrist movements. This combination can lead to hand, wrist and arm ailments such as carpal tunnel syndrome and tendinitis," said Donna Stanton of the US Society of Hand Therapists.

"Many users spend hours on their BlackBerries and iPods, responding to e-mails and spooling through music lists. These devices are getting smaller with even more features, which encourage heavy, extended use.

"More of the population could suffer hand ailments unless they learn to take preventative measures."

Stay in control

Use of a dial requires unnatural movements that can cause permanent damage

The problem

The action needed to move the wheel on an iPod is unnatural and effectively separates the joint in the thumb every time it is used.

This causes inflammation in the thumb or fingers and can be very painful.

This can even spread as far as the elbow and neck. Once people have problems in their fingers, this can affect their whole posture.

How to avoid it

Don't use your thumb to scroll. Instead hold the iPod in one hand, and use the finger of your other hand to move the wheel.

Use a neutral grip the wrist straight, not bent.

Switch the hand you use to hold your iPod frequently.

Rather than choosing songs individually, set up a playlist, or simply put your iPod on shuffle mode so it chooses the music.

Other ailments

Texter's thumb First hi-tech problem.

MP3 hearing problems Users listening to music players have been warned high volumes can permanently damage hearing.

TV eye Long periods staring at a television or laptop screen can cause sight problems.

Blackberry thumb Users of the e-mail phone have reported Repetitive Strain Injury-like symptoms.

PlayStation thumb Movements in games have led to a rash of problems among games addicts.