Doug French, of the Maths Association, said a government drive to boost the quality of teaching in maths would fail unless ministers took radical action.
The Government has announced a new national centre for excellence in maths teaching.
But Mr French said this would be a "damp squib" unless it was linked to a major programme of professional development for all staff, backed by guaranteed time to attend courses.
Mr French was speaking in a personal capacity, but his association believes staff shortages are blighting the subject.
Many students are taught by non-specialists, the Government's inquiry into the future of maths was told last month.
Mr French said schools were reluctant to send teachers on courses during the school day because of the shortage of cover. He said the Government should consider cutting the school year, set at 190 days, if it was serious about professional development.
He said: "I realise this is controversial. But we have to consider the quality of what is taught, as well as the quantity."
The Government is giving all teachers half a day a week away from lessons by 2005, but this is for marking and preparation, not for training.
Maths teachers and academics have welcomed the centre of maths excellence, but ministers are still looking for a sponsor. The pound;25 million national centre for excellence in science teaching, announced last year, is being funded by the Wellcome Trust. It is also unclear how the maths academy will link to grassroots professional development work done in schools.
The Government has asked Professor Adrian Smith, principal of Queen Mary College, London, who is leading the Government's inquiry into the future of maths, to advise it on costs and details.
Professor Smith's inquiry has been extended by three months to September after he said that the eight-month timetable was too tight.