Johansson himself has said that during the past year he has felt overtrained.
He then suffered from covid-19 and was on a respirator.
Now the 22-year-old has beaten his personal best, which was also a Swedish record.
The Swede swam 800 meters freestyle at 7.49.14 today at the Olympic Games.
The previous record was 7.49.77, from the Swim Open in Stockholm 2018.
Persson on to the semi
Erik Persson also competed today.
The 27-year-old made a steady effort when he advanced to the semifinals in the test sessions of 200 meters breaststroke.
He landed a third place in his heat and the time 2.08.76 was the sixth best of the day.
The semifinals will be decided during the night towards Wednesday.
The 800 meter freestyle competition is in progress.