This is how Sławosz Uznański-Wiśniewski is getting back into shape after his comeback. He's using special technology.

The European Space Agency (ESA) posted a photo of Sławosz Uznański-Wiśniewski exercising at a gym in Cologne on Friday on its X portal. The astronaut is using, among other things, an "anti-gravity" treadmill.

"And we're back to the gym!" the ESA post stated. It explained that the Polish astronaut was using an "anti-gravity" treadmill —as part of what it described as a recovery program aimed at adapting to Earth's gravity.

The device simulates weightlessness by using air pressure to reduce body weight, which causes less strain on joints and muscles, the agency said.

After returning from orbit, Uznański-Wiśniewski arrived on Wednesday in Cologne , home to ESA's European Astronaut Centre . There, at the German Aeronautics and Space Centre's (DLR) "Envihab" facility, he is undergoing rehabilitation, and ESA's space medicine team is monitoring his health and condition.

On Tuesday, members of the Ax-4 mission— Pole Sławosz Uznański-Wiśniewski, American Peggy Whitson, Hungarian Tibor Kapu, and Indian pilot Shubhanshu Shukla —returned to Earth after a stay on the International Space Station (ISS). The Dragon Grace capsule they carried splashed down in the Pacific Ocean near San Diego, California (USA). The Ax-4 crew spent 18 days on the station and a total of 20 days in space (including travel to and from the ISS).

Uznański-Wiśniewski is scheduled to arrive in Poland in the middle of next week. He announced upon arriving in Europe that he would spend about a week in the country and then fly to the United States.