Perkins has applauded the decision to postpone the Olympics for 12 months, saying it would not have been a level playing field if held this year due to different pandemic restrictions around the world for athletes, particularly swimmers.

"When you come off a high training load and just stop dead, the body goes into repair shutdown very quickly and you start to lose fitness very fast," Perkins told AAP.

"That is one of the reasons our team was calling for the Olympics to be postponed originally because there were athletes in Europe who had been in lockdown for a period of time.

"Even if they started training today they were not going to be fit at the highest level for July.

"It was certainly an appropriate thing to do."

However, Perkins said some swimmers still may not be able to reach full fitness by 2021 with uncertainty surrounding when athletes can again access pools.

"For me personally for every week I had off I needed two to three weeks to get it back," he said.

"When you start extending it out to three to six months, for some athletes it could take them a year to get back to where they were.

"There is no doubt even with the time frame we have got there will be athletes who are going to find it very difficult to get back (full fitness) in time."

With pools and swimming programs closed due to pandemic restrictions, athletes sick of dry land training have had to get creative to return to the water.

Olympic 10km champion Sharon van Rouwendaal of the Netherlands set the bar when she posted on social media video of her swimming in an inflatable backyard wading pool, remaining stationary thanks to a rope around her waist tied to a nearby post.

Perkins applauded the Dutch champion's ingenuity but admitted not all swimmers would be able to access water, sparking concerns racing may affected in 2021.

"I saw a very funny Instagram post from the Netherlands training in a blow up pool," he said.

"There are some creative ways to get around it. Some will but some won't and that is where the level playing field comes into it."

Asked if the standard in the 2021 pool may be affected by the shutdown, Perkins said: "If we are still not training in a year's time then absolutely.

"But if everyone is back in the water in the next two to three months then they will be fine.

"It will depend entirely on how long athletes are out of the water."

Australian Associated Press