Many girls and young women are missing out on the benefits of playing sport due to a "gender gap", the charity Women in Sport has claimed.
Sport Wales figures for 2015 showed 69% of girls played sport outside school at least once a week compared to 74% of boys.
Women in Sport blamed "a lack of female sporting role models in the media".
Sport Wales said it was working to boost numbers of girls in sport, with a third more playing football last year.
Women in Sport will give evidence on Thursday to the Welsh Assembly's health, social care and sport committee into physical activity of children and young people.
Policy manager Laura Matthews said: "Many girls and women are missing out on the benefits that being active provides, such as improved health, reduced risk of disease, an increase in confidence, improved mental health and higher educational attainment.
"There is also a lack of female role models working and volunteering within the higher levels of sport in Wales.
"For example, only a third of chairs in national governing bodies of sport are female and only a quarter of chief executives are women in Wales."
Sport Wales said the proportion of young people involved in regular sport and activity rose from 27% in 2011 to 48% in 2015, according to the latest available figures.
The Welsh Government-funded organisation said it had focused its resources on boosting participation among women and girls, black and minority ethnic communities, people with disabilities, and communities in deprived areas.
A spokesman said: "Our Calls4Action project invested £3m specifically to address inequalities, including participation for women and girls.
"Girls' football has grown significantly, with the number of registered players increasing by 32% in the last year. The Welsh Rugby Union recently revealed that 10,000 girls now play rugby in Wales."
Sport Wales added its board had equal representation of men and women.