David Cameron has criticised teachers who are unwilling to help coach young talent as he called for a return to the "competitive ethos" in school sports.
The Prime Minister said more needs to be done if Britain is to build on its success at the London Olympics.
He was speaking the day after Sir Chris Hoy's second win in the Velodrome took Britain's medal tally to 48 - 22 gold, 13 silver and 13 bronze - the most since 1908.
The Prime Minister said the problem was not simply one of money, but of "some teachers not wanting to join in and play their part".
He told LBC 97.3 FM radio: "If we want to have a great sporting legacy for our children - and I do - we have got to have an answer that brings the whole of society together to crack this, more competition, more competitiveness, more getting rid of the idea all must win prizes and you can't have competitive sports days.
"We need a big cultural change - a cultural change in favour of competitive sports. That's what I think really matters."
Mr Cameron's remarks drew an angry response teachers' leaders who said they were "extremely unfair".
The Association of School and College said the selling off of playing fields, with 21 approved for disposal since the Coalition came to power, the lack of facilities and the removal of funding were key factors in the decline of sport in schools.
Chris Keates, general secretary of the NASUWT teaching union, added: "The real issue is the major cuts that this coalition Government has made to school sports."
On the sale of fields, the Government has said the schools concerned were being closed or merged, the land involved was marginal, or it was for reasons of improving sports access.
Olympics Minister Hugh Robertson promised maintaining funding for elite sport would be his top priority after the record-breaking performance of Team GB.
Meanwhile, a postbox that was painted gold in Jessica Ennis's home city to celebrate her Olympic triumph was vandalised within 24 hours.
Sheffield City Council leader Julie Dore said she hoped the culprit felt "thoroughly ashamed of themselves". Royal Mail has repainted the box, in Barkers Pool.