Clarke Carlisle: PFA chairman and Northampton defender retires
Players' union chairman Clarke Carlisle has decided to end his playing career.
The 33-year-old's final game was Northampton's 3-0 League Two play-off final defeat by Bradford at Wembley.
Carlisle hopes to stay in post with the Professional Footballers' Association and plans to hold talks with chief executive Gordon Taylor.
He said: "One of the requirements for chairmanship is to be a current professional, but I won't abandon and leave the union in the lurch."
Carlisle made his league debut for Blackpool in 1997 and also played for Queens Park Rangers, Leeds, Watford, Luton, Burnley, Preston and York during a career in which he played more than 500 matches and won three caps for England's Under-21 side.
He said he was "utterly delighted" with his career but the time was right to bow out.
"It wasn't an easy decision but the fact of the matter is that my body can't do what I want it to do anymore.
"I can look back on my career with a whole spectrum of emotions. I have played at Wembley, the Millennium Stadium, represented my country and played in the Premier League," he told BBC Radio Northampton.
Carlisle made 18 appearances for Northampton during the 2011-12 season and returned to them on loan from York last November before completing a free-transfer move three months later.
He was under contract with the Cobblers until the end of next season and manager Aidy Boothroyd admitted he was surprised by Carlisle's decision to end his career now.
"He has done well for us, he was part of the team who got us out of trouble last season," said Boothroyd.
"He is a leader and an organiser and we wish him well."