(Supplied photo shows Japanese sprinter Yoshihide Kiryu working out indoors on his YouTube channel)

Since the coronavirus pandemic largely moved indoors the lives of adults and children in Japan, many athletes have been giving the benefit of their expertise on social media to help viewers and followers stay trim without having to venture outside.

Olympic medalists and domestic sports stars are among those who have reached out to those who followed the advice of government and local authorities to stay home in a bid to curb the spread of the virus.

In a video uploaded to his official YouTube channel last month, sprinter Yoshihide Kiryu and his coaches introduced several exercises aimed mostly at junior high and high school students.

Kiryu, a silver medalist in the men's 4x100-meter relay at the Rio de Janeiro Olympics in 2016, demonstrated workouts, such as lunging and balancing on one foot, and offered tips to those watching the near-14-minute video on their computers, smartphones or tablets.

"I think how much you can concentrate on one exercise is what allows you to close or widen the gap between you and your rivals, so I've introduced muscle and balance training that you can do on just one tatami mat," said the 24-year-old.

Many students showed appreciation for the video in their comments, saying, "I'm so glad to have this video when I don't get to go to school", and "Thank you. I've been practicing by myself, so this video really helps."

Sports around the world have been put on hold due to the deadly virus, first reported in China last year.

This summer's Tokyo Olympics and Paralympics were postponed for a year following repeated requests by athletes and sports governing bodies to change the schedule, many domestic tournaments and leagues have been canceled or postponed, and some athletes are struggling to train due to the closure of facilities.

Nippon Professional Baseball has not decided when its season, due to start on March 20, will actually get under way, and the J-League, Japan's professional soccer league, suspended its season in February.

Meanwhile, domestic rugby and basketball leagues have abandoned the rest of the season as the country grapples with an uptick in the number of infections.

On Tuesday, Prime Minister Shinzo Abe declared a state of emergency for Tokyo, Osaka and five other prefectures after an alarming growth in cases in urban areas, again calling for people to stay indoors.

On the same day, the Japan Boxing Federation posted a clip of Sena Irie, who has secured a Tokyo Olympic berth in the women's featherweight division, giving advice on how to improve core muscle strength.

"I think we will continue to have difficult days under these circumstances, but we should all work hard," she said. "We should do whatever we can, so the coronavirus (outbreak) will end."

Japanese pro baseball powerhouse the SoftBank Hawks posted a series of videos online that allow viewers to learn the essence of the sport from manager Kimiyasu Kudo and his players.

"It's difficult to play baseball (outdoors). But I hope this helps relieve the stress of children," Kudo told reporters last month.

In a video uploaded this month, pitcher Nao Higashihama demonstrates how to practice throwing at home. He shows how to improve control with the use of a towel before Kudo explains the mechanics behind the exercise.

Meanwhile, the Japan Football Association has also created clips to help people stay healthy indoors. While some of it involves kicking the ball indoors or stretching, one clip shows how a child can develop quick reflexes in an exercise done with a parent.

"Soccer can even be played alone. We wanted to deliver (the videos) to children who feel stressed or anxious. The players willingly agreed to this idea," said Hiroshi Tada, a JFA official.

Maya Yoshida, captain of the men's national soccer team, advised that people stay home, considering his experience witnessing the coronavirus tragedy unfold in Italy, where he moved to after agreeing to a contract with Serie A club Sampdoria in January.

"Looking at the situation in Italy, I think everyone let their guard down when the outbreak started. Maybe people in Japan think it's something that's happening in Europe, but the virus spread really quickly," he said.