The Olympic and Paralympic Games are meant to be the ultimate test for competitors from around the world, and so it has proved with the mental strength of would-be Olympians and Paralympians challenged as never before by the incursions of the COVID-19 pandemic.

Fear and doubt; doubt and fear. Hope and despair; despair and hope. For those trying to ready themselves for the ultimate test of their mind, body and spirit - citius, altius, fortius - the fluctuating messages surrounding the ill-fated Tokyo 2020 Games have been deeply disturbing and distracting.

Following the original postponement of the Games from 2020, the new Olympic starting date of July 23 this year has been viewed by many with an increasing sense of incredulity, although both organisers and the International Olympic Committee (IOC) have pushed back.

Earlier this year, IOC President Thomas Bach insisted there was "no reason whatsoever" to think Tokyo 2020 would not open as planned and that there was "no plan B".

When British newspaper The Times ran a story which said the Japanese Government had already privately concluded Tokyo 2020 would be cancelled, quoting a member of the Japanese cabinet, another tremor went through the sporting movement.

British Para-athlete Stefanie Reid, a three-time Paralympic medallist and the 2017 world champion in the T44 long jump, expressed the emotions of many when she tweeted in response to this latest twist to the tale.

"This is exhausting," the 36-year-old said. "If it is true, make it official. If it's just a rumour, stop playing with emotions and mental health to sell stories."

Bach responded by saying such speculation about cancellation was "hurting athletes". Sebastian Coe, the President of World Athletics, expressed his concern about athletes being "swept along from rumour to rumour".

For the vast majority of potential Tokyo Olympians and Paralympians, the sense of uncertainty has remained almost to the last minute.

Of course, nobody in the world can be certain of the immediate future in the current circumstances. But, most people in the world do not face the task of presenting their best-ever self to a challenge in just over a month's time, that may prove to be a once-in-a-lifetime experience.

While most opted to wait, there are a number of distinguished athletes, many of them nearing the end of their careers, who decided another year of training and hoping for Tokyo 2020 to take place was just too much to ask. So they have retired.

Even the lure of competing at a home Games has not proven enough to keep some athletes on track to Tokyo.

Japanese women's volleyball player Risa Shinnabe, for instance. The 30-year-old announced her retirement from the sport in June, citing an injured right hand as a major reason.

Shinnabe said her plan was to end her playing career after competing at the Tokyo Games, but she could no longer commit after her injury required surgery in April.

"I thought that it would be a little difficult for me to play as well as I would hope to and contribute to the team in a year from now," she said.

The London 2012 bronze medallist said she was "devastated" when she heard the Games would be pushed back to 2021 because of the COVID-19 pandemic.

"That one year, to me, felt very long," she said.

When asked about her plans if the Games had gone ahead as scheduled last year, she responded: "I was going to do my best to try to be one of the 12 players on the roster."

But in the end Shinnabe, who missed the Rio 2016 Olympics due to injuries, decided to step back.

"I've felt that it was getting more difficult to maintain my physical condition and my performance was declining year in and year out," she said.

"And I could no longer imagine that I would be able to go through the same cycle for another year and maintain my condition."

Women's basketball point guard Manami Fujioka is another Japanese athlete for whom the Tokyo 2020 timing has been especially bad. In January, after returning to action following an ankle problem, the 27-year-old suffered a further injury which caused her to lay aside her ambition to compete in the Olympics.

One of the highest profile athletes who has decided the Olympics in 2021 are a year too far is China's badminton legend Lin Dan.

In July last year, at the age of 36, the men's individual gold medallist at the Beijing 2008 and London 2012 Olympics announced he would not be continuing his career in the hope of appearing at a fifth Games.

"From 2000 to 2020, after 20 years, I have to say goodbye to the national team. It is very difficult for me to say it out loud," Lin posted on his Sina Weibo account.

The phrase "Lin Dan retires" quickly earned 180 million views on Weibo within hours, with many expressing their dismay.

Lin won 666 singles matches, including his two Olympic golds and five individual world titles.

"My physical capabilities and injuries won't let me fight with my team-mates anymore," he wrote.

"I've dedicated everything to the sport I love. My family, coaches, team-mates and fans have accompanied me through many happy times and difficult moments."

With 15 months between the announcement of the Tokyo 2020 postponement and the new scheduled start date, numerous others have concluded that the delay is insurmountable.

Japanese rugby union winger Kenki Fukuoka took the decision to retire in order to pursue a medical career.

Fukuoka, now 28, had planned a last hurrah at the Games, where he would have been a key player for the hosts in the rugby sevens after producing inspirational performances for Japan at their home Rugby World Cup in 2019.

Japan would have been looking for the type of display he put in during that tournament, where he scored four tries as the hosts went on a run to the quarter-finals.

But, on the pitch at least, there will be no more home heroics from Fukuoka.

Eddie Dawkins, New Zealand's three-time world champion and Olympic silver medallist from Rio 2016, is another top performer who believes the delay to the postponed Games is a bridge too far.

Dawkins retired from cycling in April, a month after the Games were delayed. He "wanted to commit everything I had into one last Olympic campaign for Tokyo 2020" as part of the men's sprint team, but the wait was too long.

"To now face a further year on top of that, and with no certainty even then, is a step too far for me," the 31-year-old said.

Dawkins' compatriot, hockey player Gemma McCaw, has also decided against a fourth Summer Games after retiring ahead of Tokyo 2020.

She played 246 times for the Black Sticks with her first Olympics coming at Beijing 2008. She finished fourth twice, at London 2012 and then Rio 2016, and has relinquished her hopes of a medal.

McCaw, who is married to All Blacks rugby union legend Richie, first stepped away from hockey after Rio, giving birth to their first child two years later. But she intended to make an Olympic return and resumed action with the Black Sticks in February 2019.

"When I came out of retirement to rejoin the Black Sticks, I was so excited to be back playing and working towards the 2020 Tokyo Olympics," the 31-year-old wrote on Instagram when announcing her decision. 

"No-one could've imagined a global pandemic getting in the way of that dream, but there are things beyond our control. Lockdown taught me many things, but most importantly those seven weeks at home brought into focus just how important family is.

"So, with that in mind, I've made the decision to end my Black Sticks journey here. I am so glad I gave it another shot and I'm proud to have done this as a mum, but I feel it's time now to focus on our family."

British rower Tom Ransley, an Olympic champion in Rio 2016 as part of the men's eight, was planning to compete at a third Summer Games in Tokyo.

However, the 35-year-old, who also won bronze at his first Olympics in London, has hung up his oars.

"Rio was very special," Ransley said. "I had a brutal time trying to get myself there, as did the rest of the crew. There were some really tough individual journeys along the way and I'm incredibly proud to be in the company of that eight."

Australian basketball player Andrew Bogut, who had planned to compete at his fourth Olympics in Tokyo and seek a place on the podium having finished fourth at the Rio Games, is another who has found the hiatus too demanding.

The 36-year-old conceded he would need to take "a lot of painkillers" to get to Japan, but felt it was "just not worth it" while claiming his body was "hanging by a thread".

Australian hockey co-captain Jodie Kenny, 33, decided the lure of trying to earn an Olympic medal at the third attempt was not enough to enable her to do what she knew was required to be in peak condition.

"Making this decision to retire was a mix of everything," she said.

"Emotions, motivation and uncertainty around what things will look like with COVID and the extra commitments around travel and quarantine periods.

"My heart was still wanting to go on and play but my head just wasn't anymore."

Others at the top of their sport have deliberated whether to go the extra mile to the shifted Games - and no-one has done so with more intensity than multiple Olympic and world gymnastics gold medallist Simone Biles, who made her ambivalence very clear before finally opting to extend her career until the other side of Tokyo.

The 24-year-old from Columbus in Ohio was one of many to suffer at the hands of disgraced team doctor Larry Nassar, and has been a strong critic of what she sees as the inadequate preventative and restorative measures taken by USA Gymnastics.

In tennis, identical twins Bob and Mike Bryan, who have won multiple Olympic medals in doubles, including the men's gold in 2012, and have won more Grand Slams than any other men's pairing, decided in August they would retire. The decision of the 43-year-old Americans came when it became clear what they hoped would be a farewell tour of their favoured courts would in fact be empty stands and remote viewing.

Julia Görges, one of Germany's leading tennis players, also made an unexpected announcement of her retirement.

Aged 32, she decided life outside her sport, which the pandemic lockdown obliged her to experience more fully than she had for many years, was calling her to new things.

"It just showed me how nice life can be away from tennis, too," she said. "If you just have it for two to three weeks like in the off-season, [retirement] never comes to your mind, but if you have stayed away from the tour for five to six months, it just opens up a whole different new chapter."

Happily, the Tokyo delay has worked the other way for some athletes for whom last year would have been an impossible ask. Britain's Helen Glover, who won coxless pairs rowing gold with Heather Stanning at the London 2012 and Rio 2016 Olympics, is one who will benefit.

At the age of 34 and having had three children since retiring after Rio 2016, Glover announced in January she was back in full-time training.

"As my scores and times started getting better, I began to wonder if I could be the first woman in British rowing history to make an Olympic team after having children," she said.

"I'm finding the journey exciting and extremely challenging."

Victory in the European Championships with partner Polly Swann made her ambition yet more realistic, and this month she received the news that she was in the Tokyo 2020 team. Her husband, TV naturalist and explorer Steve Backshall, will be looking after the kids...