Kids are being warned to limit the amount of time they spend texting and playing computer games because it could lead to aches and pains in the future.
Doctors say more and more children are coming to them complaining of tingling and numbness in their hands and wrists.
The condition is known as repetitive strain injury (RSI). It's brought on if your muscles are put under strain by doing the same movements.
Experts say they want kids to be aware of the condition and to take care.
Newsround spoke to 12-year-old Alex, who has RSI in both hands after playing computer games for a long time.
"I was spending four to five hours on my computer every day," said Alex.
"I noticed that my arm was starting to ache."
Experts say kids' muscles and bones are not fully grown and the extra strain means they are in danger from RSI.
One doctor told Newsround: "We need to deal with it, or it will get worse."
The doctor said more needs to be done to teach kids about the dangers of texting and playing computer games too often.