They’ve endured a delayed Olympic Games, rigorous COVID-19 testing requirements and logistical hurdles. But the next biggest test for Olympians may be competing without anyone in the stands.

Driving the news: Psychologists don't know for sure how a spectator-less Olympics will impact athletes' performance, but Olympians are already expressing concern about what it will be like to compete without hearing the cheers of their families and fans.

• "I like to feed off of the crowd," U.S. gymnastics star Simone Biles recently told AP. "I’m a little bit worried about how I’ll do under those circumstances."
• "Hearing [coaches and teammates] talk about the energy from the crowd just sounds really amazing and inspirational and I am disappointed that I won't be able to experience that," Valerie Constien, a first-time Olympian in the women's 3,000-meter steeplechase, told Axios.

The big picture: Past research suggests that the presence of other people tends to enhance an athlete's performance, but because the Olympics are unlike any other sporting event, psychologists say it's hard to draw conclusions about how this year's spectator-less Games may or may not affect athletes in competition.

• "We don't really know" what the impact will be, said Sam Sommers, a Tuft University psychology professor and co-author of “This Is Your Brain on Sports."
• "Yes, the Olympians will be performing in front of empty arenas, but at the same time, they will be performing in front of millions and millions of virtual eyes watching on TV and the internet, and other very high-stakes conditions with Olympic medals on the line," Sommers told Axios. "It’s hard to know exactly how all of that will play out psychologically."

The "bigger concern" may be that athletes' families will be thousands of miles away, said Peter Haberl, a senior sports psychologist for the United States Olympic Committee.

• "It means the world to [athletes] to have their family there and to share the experience in person," Haberl told Axios.
• Sommers added that the "social support" families and friends provide is important especially for athletes' mental health. "I know it's only a couple of weeks ... [but] there's something to that idea that that might be just as big if not a bigger influence" on athletes, he said.

Constien explained that not having her sister and boyfriend with her in Tokyo is "going to be the most difficult part."

• "At the Olympic trials, my sister and my boyfriend were very instrumental in helping me stay calm before the race and going on runs with me before the race ... and getting to embrace them both after the final was so rewarding," she said.

Despite the worries, psychologists said the last year of fan-less sporting events likely provides a glimpse of what is to come in Tokyo.

• "We have already seen that wonderful performances can help in the absence of fans," Haberl said, citing performances in the French Open, the U.S. Open and the NHL. "So again, this does not have to get in the way of performance."

The bottom line: While it is unclear exactly how, if at all, athletes may be impacted by the fan-less Olympics Games, "everyone's in the same boat," Sommers concluded.

• "Everyone's competing in the same track with no spectators, everyone's competing in the same swimming arena or basketball court, so everyone's subject to the same thing."

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