Organisers of the Brighton Half Marathon have apologised to runners after finding out its course had been 146m short for the last three years.
An investigation found a turning point just after the four-mile mark, near Roedean School, had not been positioned properly.
Organisers said the concerns, bought to them by UK Athletics, were based on an analysis of the GPS data of various runners.
In a statement they said: ‘We are devastated that this mistake has happened and apologise unreservedly to all runners who took part in the affected race years.’
This year’s race took place on February 26.
Simon Dowe, chief executive of the Sussex Beacon, the charity which organises the race, said: ’We can’t apologise enough for this mistake. I know it’s hugely disappointing to everyone who trained so hard.
‘I also know that for some, the news will be devastating as it affects race times, personal bests and records. Our thoughts are very much with the runners.
‘I’m so sorry that their remarkable achievements and the money raised for good causes may be overshadowed by this error.’
It is not the first time race organisers have been forced to apologise to runners, after revealing the course was too long in 2012.
Race director Martin Harrigan said: ‘We are a team of runners ourselves so we fully understand the impact of this news.
’We are really upset that this mistake has happened and we take full responsibility for this situation.
’We remain committed to making the 2018 Brighton Half Marathon a great event.’