How the ban on spectators at Tokyo Olympics could impact athlete performance

Japanese Prime Minister Yoshihide Suga confirmed Thursday that Olympics events in Tokyo will have no spectators at any of the Games' venues.

The prime minister went on television and announced to the nation that a state of emergency with new COVID-19 restrictions will go into effect on July 12 and will remain in place through the Olympics.

After being delayed for a year, the Summer Olympics are scheduled to run from July 23 to Aug. 8.

Seiko Hashimoto, president of Tokyo 2020, said: "As for Tokyo 2020, a very heavy judgment was made" and that officials had "no choice" but to hold the games in a "limited way."

"There are many people who were looking forward to the Games. Those people who purchased tickets as well as the local community people. We are very sorry we are able to deliver only a limited version of the games but we want to have through operations to ensure a safe and secure games so that the people world over will be able to find the Olympic and Paralympic ideals," Hashimoto said.

The Tokyo Olympics organizing committee had already ruled that spectators from abroad won't be allowed "due to the prevailing worldwide COVID-19 pandemic," including the emergence of more contagious variants.

Tournaments and leagues across the globe have been slowly welcoming back fans, often at reduced capacity, in recent months. The 2020 Games will feature over 300 events representing 33 different sports. For the elite athletes competing, the question of whether fans' attendance can impact their performance, is an important one.

"Fundamentally, my experience in coaching professional and college athletes is that any change to the performance environment causes some level of stress," Jonathan Fader, a psychologist who has worked for the New York Mets and New York Giants and a founder of the coaching practice SportStrata, told ABC News. "That change could be weather, that change could be a new coach, that change could be fans."

There haven't been studies done during the pandemic on elite athletes and their performance with or without fans, Sam Sommers, a psychology professor at Tufts University and co-author of "This Is Your Brain on Sports," told ABC News. But "we do know that the presence of other people is physiologically arousing, it makes our heart beat faster, it focuses our attention on what we're doing," he said.

"We do perform differently in front of other people than we do on our own," Sommers said. "There are research findings that suggest that performing in front of others can be a good thing when you're doing something that is familiar and that you're well-practiced in."

Athletes themselves have talked about the difference with fans back in attendance. French tennis player Gael Monfils told ESPN that playing in front of a larger crowd at this year's French Open was "incredible."

"I could feel their energy. It definitely made me so happy. Cannot be happier than that," said Monfils, who reached the second round of the tournament. "I was missing the crowd."

For the home nation, there may also be benefits from an exuberant Olympics crowd. An analysis published in the Journal of Sports and Sciences in 2003 found that crowd noise can influence officials' decisions, resulting in a greater home advantage.

Whether or not fans in attendance matters could largely depend on the sport. The crowd at a professional baseball or basketball game is not the same as what you'd find in golf, for instance, Sommers said.

"I mean this with no disrespect, but your average archer or rower may not be used to performing in front of large groups, so the effects may be different," Sommers said. "You couldn't offer blanket across-the-board predictions, but there is evidence that suggests that the presence of a lot of people can change our performance."

Well-trained, seasoned athletes who typically compete in front of large, loud crowds are likely to train for those conditions to tune out any distractions, Fader said.

"What we know is that it helps, usually, to train under the same circumstances that we're gonna perform," Fader said. "What a lot of people do is they'll actually bring in crowd noise. [NFL football coaches] will train players in the cold if they know they're gonna play in the cold."

While some athletes may thrive off the energy of fans, there could be benefits to having no crowds in attendance, Fader said.

"There's less to focus on, and there's no one heckling you," he said.

A lack of a home crowd in particular could take the pressure off hometown athletes, one sports psychologist told Reuters ahead of the 2012 London Games.

At Fader's practice, which works with Olympic athletes, coaches help competitors deal with crowds in part through a mental practice called imagery.

"It helps you in terms of your ability to deal with crowd noise, or non-crowd noise, if you've mentally practiced that situation," Fader said.

Whether or not spectators are in attendance is part of a larger question about "not knowing what normal is anymore," Sommers said.

"This is a question not just about sports, it's for the whole world -- what's it going to be like in my college classrooms in the fall? What's it going to be like in restaurants? What does the future hold?" Sommers said. "All the stuff that we've learned over time is thrown into question. We're figuring it all out, sports is no different."