"Two years ago, I became a father of a son and my wife and I are expecting twins in February", Kooiman said. "In recent years, I have been away from home a lot to be able to skate at this level, so now I am looking forward to spend more time with them. It has been a difficult decision. To be honest, I had some sleepless nights, but I know this is the right thing to do. Now it's time for my family."

In 2018, Kooiman won the Alternatieve Elfstedentocht on the Weissensee after a long solo. In doing so, he followed in his father's (Jan Kooiman) footsteps, who was the strongest on the lake in Austria in 1993. He also managed to get two World Single Distance Championships medals. In 2015, he took silver in the men's 10,000-meter race at Thialf and a year later he captured bronze on the longest distance in Kolomna (Russia). Since December 9th of 2015, he has been the holder of the World Hour Record, which he set in Inzell: 43.735,94 meters.

"I look back on a wonderful speed skating career, since I was able to show some great things. For me, it is difficult to say what my absolute highlight has been. My win on the Weissensee and the World Hour Record are at the same level, but I am also still very proud of my two World Single Distance Championships medals. "

Now that the marathon competition is currently still due to COVID-19, Kooiman has only raced a few long track races this current skating season. At the qualification tournament for the World Single Distance Championships at Thialf, he finished fourth in a time of 13:00.76 in the men's 10,000-meter race. In the 5,000 meters, he ended up in eleventh (6.24.50) place. Earlier this season, he also participated in the Dutch Single Distance Championships. He finished eighth (5,000m) and fourth (10,000m).

"My 10K at the qualification tournament was a good race, but unfortunately not good enough for qualifying. Therefore, I hope that this season, there will still be some marathon races on natural and or artificial ice so that we can fight for victory with the team. It would be a nice way to end my career. If it happens, I will enjoy my last laps in the leading group even more", Kooiman said.