Research over the past 10 years has shown that girls take part in PE and games as much as boys in primary school but are six times more likely to try to avoid games when they reach their teens.
In a report to be presented to the Royal Society of Medicine women's health conference next week, Professor Neil Armstong, of Exeter University, blames overprotetive parents, lack of role models and uninspiring lessons.
He says the emphasis on competitive games has alienated teenage girls. He says:
"Girls may get a less inspiring, 'watered down' version of the boys' curriculum when what they want is individual or pair activities. It's much easier to join an aerobics class than get a group of more than 20 people together to play hockey."
A recent survey found that girls hated sports and swimming because it spoilt their hair and they did not like getting sweaty.