Team sport is the only type of extracurricular activity to make a significant and consistent difference to students' academic grades, research has found.
Students who belong to extracurricular sports clubs are also more likely than their peers to complete their school education and go on to university.
Academics from the University of South Carolina and Pennsylvania State University, both in the US, studied data from 9,700 high-school students aged 14-18. The students attended schools in a range of urban, suburban and rural areas.
The academics found that students who lived in rural areas were more likely to take part in all kinds of extracurricular activities than their city-dwelling and suburban peers.
But the most significant findings related to the effect that after-school clubs had on academic achievements. Team sport was the only extracurricular activity to have a consistent and significant effect on students' grades across all schools.
Lead author of the study, Matthew Irvin, from assistant professor in the Department of Educational Studies at the University of South Carolina, said: "Sport allows you to develop a mentoring relationship with adults and with positive, school-oriented peers. They help socialise you into being more focused on school, and may help develop time-management skills, initiative and an ability to work with others."
Eileen Marchant, of the UK's Association for Physical Education, said being "physically able and physically competent often complements academic ability".
"It raises self-esteem and self-belief, and there's an absolute correlation between believing in yourself and what happens in other areas of the curriculum," she said.
Other activities were not without benefits, however. In urban high schools, for example, students who enrolled in academic clubs were likely to progress to college. And rural students who signed up for vocational or performing arts societies were also likely to go on to enrol on a degree course.
The academics found that the positive effects of such activities remained the same regardless of students' socio-economic backgrounds. But only sport had a consistently positive effect across all schools and all measures of academic success.
"Sport is often what brings a community together," Professor Irvin said. "The big event for the weekend is the high-school football or basketball game. It's what children are participating in. Maybe there's just more personal interest."
Ms Marchant attributed the positive impact to sport's competitiveness: "So much of extracurricular sport is focused on games, which are competitive... You're competing against yourself in PE, even in something like dance or gymnastics. Success does breed success. There's no doubt about it."