Girls are more likely to enjoy sport at single-sex schools because there are no boys to "impress", a leading headmistress has said.
Young women have more confidence to take part in sports activities without male classmates around, Caroline Jordan suggested.
And she argued that private schools should not be "embarrassed" by the number of Olympic athletes they have produced, but proud of the achievement.
In her speech to the Girls' Schools Association annual conference, Ms Jordan also issued a warning that, following the Brexit vote, there was a "real fear" among overseas parents about modern-day Britain.
Ms Jordan, headmistress of Headington School, Oxford, told delegates that a recent poll of GSA sports directors found that nearly three in five (59%) believe that non-competitive fitness activities now have equal status with competitive sport in their schools, with many saying that they go hand-in-hand and team sports offer girls the chance to learn skills such as leadership and build confidence.
She said: "Certainly we do see, time and time again, how girls' engagement in team sports is more apparent in girls' schools than it is in co-educational schools.
"This is partly about access to facilities - even the most progressive of our co-ed colleagues tend to schedule girls' sports once the boys are sorted - but in my experience it's really an issue of confidence and peer pressure.
"With no boys around to 'impress', I have always found that girls are far more likely to enjoy running around for an hour at lunchtime on the sports pitch than they might be in a co-ed environment."
Ms Jordan, president of the GSA, told delegates that 2016 would be partly remembered for the Rio Olympics and the top performances of athletes around the world.
"The disproportionate number of medallists and competitors - not just in Team GB - to have been educated in British independent schools has been well documented," she said.
"This doesn't embarrass me. Far from it. I believe it is something we should be proud to celebrate. GSA schools alone educated eight medallists, including silver medallist in rowing Katie Greves who is a former Headington pupil."
Ms Jordan also told the conference that schools were now facing the challenge of trying to deal with the potential impact of recent political events on pupils.
"Whatever your political leanings I doubt that many of you predicted both Brexit in the UK and the Trump victory in the US. The challenge we now face is to navigate the uncertainty and understand the potential impact on our pupils.
"Already many of us are reporting a real fear amongst our overseas parents and friends, mystified by a seemingly newly xenophobic Britain that they don't recognise or understand.
"Whatever happens with our country's plans for Brexit I believe we must maintain - and indeed amplify - our global outlook."