Health experts in Britain have warned that heavy use of smartphones may result in ailments from "text neck" to "text thumb injury", AFP reports. Making inroads

According to them the strain injuries, stemming from long periods spent staring at small screens and tapping at tiny keys, can be debilitating — and the injuries are becoming more common as high-tech gadgets grow ever more popular. This was revealed in recent YouGov poll.

The poll says that  44 per cent of Britons use their mobile phones for activities other than making calls, for between 30 minutes and two hours per day. The pollster quizzed 2034 adults over several days in September.

"I had a patient who developed inflamed tendons in her thumb from using her smartphone, and was unable to use her hand for weeks due to pain," said Tim Hutchful from the British Chiropractic Association.

"The phones are far too small, with keys that are too small," she said, noting that pain in the upper limbs forced one of her patients to stop texting, and instead switch to voice-recognition software.

As well as hand injuries, experts point to problems among smartphone and tablet users arising from hours spent leaning over tiny screens.

"The weight of an average human head is between 4.5 to 5.5 kilograms," said Hutchful.

In an ideal posture, where a vertical line can be drawn from your ear through your shoulder, hip, knee and ankle, "the weight is carried efficiently", he noted.

But if the head is constantly held forward to squint at a screen, then the unusual posture makes the head feel up to four times heavier, increasing strain across the whole body, he explained.

"Text neck" is, in effect, the latest manifestation of repetitive strain injury (RSI), a condition that affects one worker in 50 in Britain.

RSI is the name given to a group of injuries affecting the muscles, tendons and nerves, primarily of the neck and upper limbs. It is particularly prevalent among workers who spend long periods using computers and computer mouses.

It is a treatable condition, but experts warn that it is essential not to ignore the early warning signs.

In France, RSI is the main cause of sick leave in the workplace.Emmanuelle Rivoal, a Paris-based physiotherapist and osteopath, has observed an increasing number of patients who are paralysed by pain "because they spend more than five hours a day in front of a screen".

While stressing that he did not want to "demonise smartphones", Hutchful offered some pointers for gadget aficionados to avoid injury, such as keeping smartphone use at under 40 minutes.