The Ofsted chief inspector has called on the government to do more to increase sport in schools amid growing concern that physical education is being squeezed out of the curriculum as a result of funding cuts and excessive focus on exam results.

Amanda Spielman told the Observer it was essential that ministers and school leaders acted to show they understood what should be obvious – that sport and exercise for young people were vital parts of a full and balanced education.

In a summer that has already seen English successes on the national stage in the women’s football and men’s cricket World Cups, as well as progress for English tennis players at Wimbledon, she said action was also needed if the country was to continue producing stars capable of winning at the highest level. “Both government and schools should be taking this seriously if we’re to inspire the next Ellen White or Andy Murray.”

Her comments come as the government prepares to announce a new school sports action plan, following criticism that it has failed to capitalise on the 2012 London Olympics and instead sent sport in the state education sector into decline.

Research by the Youth Sport Trust, covering the 2017-18 academic year, found that 38% of English secondary schools had cut timetabled physical education for 14- to 16-year-olds since 2012, while almost one in four (24%) had done so in the previous 12 months. Separate figures produced by Sport England, cited in a recent parliamentary report, showed that just 17.5% of children and young people were now meeting the current chief medical officer’s guidelines of taking part in sport and physical activity for at least 60 minutes every day.

Spielman said Ofsted would be playing its part by recognising schools that offer sport and exercise both in and outside the curriculum in a new inspection regime to be introduced in September. “Squeezing subjects like PE out of the curriculum overlooks the fundamental purpose of education, which is surely about giving children the skills, knowledge and qualities they need to succeed in life,” she said. “Schools that offer children a broad, balanced education, including plenty of opportunities to get active during the school day and through extracurricular activities, will be rewarded under our new inspection regime.”

The Youth Sport Trust last week wrote to the two contenders to be the next Tory leader and prime minister, Boris Johnson and Jeremy Hunt, telling them that in state-funded English secondary schools “physical education has been cut by more than almost any other subject, with over 51,000 hours of curriculum PE lost between 2010 and 2017”. Its letter, backed by groups including the RFU, England Netball, England Hockey, and England Athletics, is evidence of mounting clamour from sports organisations about a perceived lack of support from government.

Geoff Barton, general secretary of the Association of School and College Leaders, said: “Sport and PE are under pressure in schools because of real-terms cuts in education funding and timetables which are bursting at the seams with all the things that schools are expected to deliver.”