Andrew Luck: Indianapolis Colts quarterback retires at 29

Indianapolis Colts quarterback Andrew Luck has announced his retirement at the age of 29 to remove himself from the "cycle of pain" caused by injuries.

Luck was the number one pick in the 2012 draft and was second in the NFL for touchdown passes last season as the Colts reached the play-offs.

But after shoulder surgery in 2016, he missed the 2017 season and has had calf and ankle problems during pre-season.

"It's taken my joy of this game away," said the American.

"It's the hardest decision of my life - but it is the right decision for me.

"For the last four years or so, I've been in this cycle of injury, pain, rehab, injury, pain, rehab. It's been unceasing, unrelenting, both in-season and off-season - and I felt stuck in it.

"The only way I see out is to no longer play football."

Last season, Luck helped the Colts reach the play-offs for the first time since 2014, which led to him winning a fourth selection for the all-star Pro Bowl game and the NFL's Comeback Player of the Year award for 2018.

News of his impending retirement led to boos from some fans when Luck walked down the touchline during the Colts' pre-season game against the Chicago Bears on Saturday.

However, there has been an outpouring of support from fans and fellow professionals following his announcement.

"I haven't been able to live the life I want to live," Luck added at an arranged news conference after the game.

"After 2016, when I played in pain and was unable to regularly practise, I made a vow to myself that I would not go down that path again."