Bone experts at the British Chiropractic Association (BCA) are getting really worried about TMI - text message injury.

It's a bit like repetitive strain injury (RSI) which usually hits computer users and game players.

When you text, you often tense your shoulders and upper arms.

This means not as much blood reaches your forearms. When you make small finger movements your hands actually need more blood supply.

Getting smaller

The bone experts say texters - especially young ones - aren't doing the proper exercises to stop them damaging themselves.

And making mobiles smaller and more dinky means texters have to make smaller movements with their hands.

The BCA says phone makers could help by making buttons bigger and thinking more about mobile design.

More people are texting every day.