It is a familiar scene at many schools: a group of adolescent boys compete to show their prowess on the sports field, while their female peers, perhaps more self-conscious about their bodies, look for any excuse not to take part.
But the reluctance of girls to participate in physical education (PE) could have a damaging effect on their health in later life, a new study has suggested.
A medical researcher in Sweden found that girls who scored low grades in PE experienced more health problems when they were older than girls who achieved high grades.
Simon Timpka, from Lund University, also found that girls with poor PE grades faced an increased risk of muscular and skeletal disorders when they were adults. The researcher said he had not found a similar link between boys' grades and health.
Dr Timpka looked at the records of nearly 2,000 people for 30 years, beginning when they were at elementary school. He used detailed population and health data, including statistics on sick leave taken, in-patient care and visits to a doctor, to measure physical impairment. He said, however, that although his study found a link between low PE grades and health problems among women, it did not "examine or determine" cause and effect.
This suggested that there could be other, undiscovered factors connecting the two, he said. Other influences, such as smoking, obesity or insufficient physical activity "could potentially explain the observations", he added.
"Girls with a low PE performance may be an important group to target with public health interventions of some sort," Dr Timpka concludes in his report.
Sue Wilkinson, strategic lead at the Association for Physical Education in the UK, said there was a problem with girls being reluctant "to engage with physical education" in many schools. "There is a drop-off at 14 and we have got to work to get them involved," she said. "It can be a problem for boys, too, but it seems to be more common among girls, where there are often issues of body image, weight and self-esteem.
"A lot is being done to widen the curriculum - for example, by introducing dance as a form of PE - and also to ensure that girls wear PE kit that they are comfortable with or that is appropriate to their culture."
But efforts needed to be boosted, Ms Wilkinson said. "The evidence suggests that, as well as the health benefits, physical education can also improve academic performance."
Dr Rachel Sandford, lecturer in young people and sport at Loughborough University in England, said that many girls were turned off sport because they thought it would make them look muscular and they associated "big" with "fat".
"That means they will not get the health benefits of being physically active when they are young and, as this new study shows, could suffer health consequences when they get older," she said. "Young girls are self-conscious about their body image and it is more of a problem today because they are bombarded with images of the 'ideal', which is portrayed as slender. Peer pressure is also a huge factor."
By contrast, the boys' ideal was more often portrayed as "strong and muscular", which was more likely to encourage physical activity, she added.
Gary Stidder, principal PE lecturer at the University of Brighton, said that a significant number of teenage girls in particular "hated" traditional forms of the subject.
He was concerned that the revised national curriculum due to be introduced in England from September 2014, with its emphasis on competitive sport, would "give the green light to dinosaur games teachers with one ball and a bag of bibs".
Dr Stidder called for teachers to be more creative and engage girls by offering activities such as yoga, pilates and cheerleading, providing clean changing rooms and allowing girls to choose their own kit.