Young goalkeepers are suffering major wrist injuries because footballs are too heavy.
According to a report in the British Journal of Sports Medicine, adult-sized balls can damage children's joints.
At one clinic, 29 broken wrists were caused by young goalies trying to make a save.
The average age of the players was under 11.
Most of the time they were using an adult football (size five). These weigh up to 450g and can be kicked at speeds of 25m a second.
The Football Association recommends that children use smaller footballs: sizes three and four weigh less and are just as good.
In fact, several professional footballers including Gary Mabutt say they learnt using tennis balls - and that smaller sizes are actually better for practising and developing ball skills.