Isolation and the absence of family and friends have taken a toll on athletes' mental health at the Tokyo Olympics, with some struggling to cope with the challenges posed by the COVID-19 pandemic while carrying their country's hopes on the global sports stage.After her stunning exit from the women's gymnastics team event on Tuesday, Simon Biles said she felt she had been carrying the weight of the world on her shoulders.That burden seems to have been exacerbated by a year of grief, loss and restrictions tied to the pandemic.Athletes have seen their pre-Olympic training disrupted by lockdowns and restricted access to athletic facilities.Their families and friends also can't cheer for them in the stands in Tokyo and their movements are heavily restricted.Biles - who also pulled out of an individual all-around competition on Wednesday - said quote: "Usually you hang out in the village, all that stuff… It does suck when you feel the weight of the world. There are no outlets with the amount of training that we do."Gymnast Angelina Melnikova of the Russian Olympic Committee, who beat the United States to win gold in the women's team event, said it has been “a difficult road since 2019."Other athletes have also contracted COVID-19 either before or even during the games threatening to derail their years of grueling work toward the Olympics.CARISSA MOORE: “I applaud her for putting herself first and doing what's right for her.”But amid the stress and fierce competition, athletes like U.S. Gold medalist surfer Carissa Moore are cheering Biles on for putting her mental health first.CARISSA MOORE: “That's hard to do in a world where people expect so much of you and have this idea of what success looks like. For her to take her power back, and just be like 'hey this is what's best for me, this is what success looks like for me.' That's really hard. “ USA Gymnastics said Biles is being evaluated to see if she can take part in the individual apparatus finals next week.