Career
He owns three national records, two in long course 800 m and 1500 m freestyle. In short course he has one national record, 1500 m freestyle. Kienhuis participated in the 2007 European Junior Swimming Championships in Antwerp, Belgium where ended 16th in the 400 m freestyle and 12th in the 1500 m freestyle.
In December 2008 at the Swim Cup Eindhoven 2008 he broke the national records in the 800 m and 1500 m freestyle, long course.
Two weeks later at the national short course champions he lowered the national record at the 1500 m freestyle.