A new study on teenagers' fitness levels has found that boys are 42% fitter than girls.
The results of a fitness challenge, carried out by researchers at Dublin City University, found that the gap between boys and girls widens as they move through secondary school.
Almost 23,000 secondary school pupils took part in the Irish Life Health Schools Fitness Challenge last year.
Professor Niall Moyna from the Centre for Preventive Medicine at DCU, says there are a number of reasons why girls' fitness levels decrease: "For young girls, other things become more important, friends actually if your friends don't take part in sport, you tend to withdraw aswell.
"A lot of girls don't find competitive sport appealing, I think particularly with physical education in Ireland, even today talk to someone in their 30s and 40s and it is a negative feeling immediately."