It is within subject repeated measure study to determine if touch screen use affect posture control in healthy adolescents.~200 normal adolescents between 14 and 18 years old will be included.~1st they will be assessed for posture control to determine normal values for their ages, then each child will be given smartphone to play a game while the sound is muted for 15 min then their balance will be re-assessed, finally they will use the phone for another 15 min but the children will use headphone piece this time then re-assess balance.
This is a study to determine if smartphone use affect posture control in adolescents.