Johan, born in Vriezenveen, had from a young age a strong interest in swimming. He hails from a family of amateur swimmers. In the small town where he was born and raised, schools include water polo and other aquatic sports in their curriculum. Johan' love of water polo, however, was sidetracked when he showed promise in competitive swimming.
In 1998, he won gold medals in both the 100 meter and 200 meter freestyle events in the European Junior Championships. At the 2000 Olympic Games in Sydney, Australia, Johan was a member of the bronze medal 4x200 meter freestyle relay team. He also helped the Netherlands win a silver medal at the FINA World Championships in Fukuoka, Japan in 2001 as a member of the 4x100 meter freestyle relay team.
However, by 2002, he was growing tired of the sport and close to retirement. His coach, Fedor Hes, helped him develop a different training strategy which involved spending more time on dry land. Seemingly invigorated by the new training style, Johan quickly progressed enough to win fourth place at the 50 meter freestyle event in the FINA World Championships in Barcelona, Spain. He was only 0.01 seconds behind the bronze medalist.
In the 2004 Olympic Games, Johan was a member of the Dutch Olympic swim team. As the starting swimmer in the 4x100 meter freestyle relay, alongside Pieter van den Hoogenband, Mitja Zastrow, and Klaas-Erik Zwering he played a critical role in securing a silver medal in the event.
Johan was one of only eleven openly gay or lesbian competitors in the 2004 Olympic Games in Athens, and also one of the youngest of world-class athletes to come out. Coming out so early wasn't intentional, he says. "I never meant to portray myself as a Gay athlete when I gave the interview to a newspaper right before Athens. It was just a subject that came along." Johan had mentioned in the interview that his boyfriend, Jose, was in Athens to watch him compete.
He says he was surprised by the small number of Gay athletes at Athens who came out. "I don't think there were only 11 Gay athletes in Athens," he says. "Reporters always talk to athletes about sports, because that's the reason why we are in the media in the first place. A subject like sexuality or something else of that nature doesn't come along in interviews that much. They are just focused on what they do best and that's competing."
Johan was also surprised by the media attention his casual revelation drew. "I never thought it would draw so much attention," he says. "But it did, and that's fine with me."
In November 2006 he announced that he would quit swimming on the highest level after the 2006 European Championships Shortourse in Helsinki, Finland. For now, Kenkhuis combines his studies in economics with his training. Johan is currently living in Amsterdam where he is a member of De Dolfijn SPAX swim club but trains with XLence Swimteam. He is a Business and Marketing major at the Johan Cruyff University in Amsterdam.