The 31-year-old made history with long-standing team-mate Helen Glover at Rio 2016 as they became the first British female rowers to retain an Olympic title when they won the coxless pairs crown.

The duo had been the dominant force in the discipline, winning 39 consecutive races since the World Championships in Slovenia in 2011, and Stanning ends her career unbeaten with her trusted partner.

Stanning, who completed a tour of Helmand Province in Afghanistan with the Royal Artillery following her London 2012 triumph, insisted she had nothing to prove and admitted she would have struggled to motivate herself in the build-up to the Tokyo 2020 Olympics.

"If I was honest with myself and said I was going to commit to another four years, would I have the same drive and determination I had four years ago?," she said to BBC Sport.

"Probably not - therefore is it worth half-heartedly committing to something?

"There was no pressure on me to make a decision this year.

"I could have taken a whole year to make that choice, but I wanted to know what I was doing.

"As last season progressed I realised I'd achieved all I ever thought I could in the sport and, as you get older, it gets harder.

“I'm quite content with what I've achieved."

The announcement from Standing brings her partnership with Glover to an end but she claims it was not difficult to tell her compatriot she was retiring as it was a decision the 30-year-old was expecting.

"It will be the end of our partnership in a rowing boat but it's not the end of our friendship and that's just as important,” added Stanning.

“It seemed a normal, natural conversation, and I'm sure it was of no surprise to her.

“It was a great success and hopefully people enjoyed watching and supporting us as much as we enjoyed being part of it."

Glover thanked Stanning for the "success we shared" and for "making it the most fun journey possible".

"Heather has been my teammate for six years and in that time has been my voice of logic, a driving force, my friend, and my maid of honour," she said.

"I'm fortunate enough to have sat at the start line of two Olympic Games with Heather.

"There is nobody else I would have wanted in the boat with me in those moments.

"She is dependable, determined, and a formidable athlete."