Olympic silver medallist Christian Sprenger has retired from swimming just months out from the start of the Olympic Games in Rio de Janeiro.

Sprenger says a lack of motivation and an ongoing shoulder problem forced him to quit the sport despite feeling he could still have earned a spot in the Australian team for his third Olympics.

"The injury I sustained in 2014 really took a bigger toll on me than I thought it would," the 30-year-old said on Thursday.

"After returning in 2015, after almost four months out of the water, I worked hard to get back what I had lost, but although I may have thought I wanted it, it wasn't enough.

"Towards the end of 2015, my breaststroke just didn't feel how it used to, and I became more and more frustrated.

"The Olympic gold is the only thing missing from my collection, but in this sport, if the mind and body are not perfectly in sync and focused beyond capacity, the performance will not come.

"Ultimately for me, I am not there anymore, and although I may be good enough to make the Olympic team, I can't just be a number on a team, that is not who I am."

He said the silver medal in the 100 metres breaststroke at the 2012 London Olympics after entering the Games ranked sixth was a highlight and the world championship the following year in Barcelona made him feel "unbeatable".

"It wasn't something people could see, but it was something that I could feel, and that’s all that I needed," he said.

Simon Cusack started coaching Sprenger in 2010 and oversaw a switch to the 100m sprint race.

"During the last month of Christian's time in the training pool, after we had discussed his retirement, I spent time just watching him execute his stroke," Cusack said.

"For me, it was the end of an era, and an era which I had the privilege of guiding this young man to the lofty heights of being the best in the world at his chosen craft."

AAP/ABC