A native of Nichols, Iowa, John Oostendorp was an all-state linebacker in football and the first state champion wrestler in the history of West Liberty High School. He pinned all but one opponent as a senior and won his state finals match 10-0.

Oostendorp wrestled and played linebacker at the University of Iowa. A four-year starter at heavyweight, he was a two-time All-American and a Big Ten champion while compiling a career record of 108-26 with 40 pins. As a senior, Oostendorp defeated eventual Olympic and World champion Rulon Gardner in the third-place match. Oostendorp won the Espior U20 National Championships in 1989 and represented the United States at the U20 World Championships, finishing fifth.

His redshirt freshman year at Iowa, he won the Junior Greco-Roman National Championships and represented the U.S. at the Junior World Championships, finishing fifth. Oostendorp competed in the 1995 World Championships and won the 1996 Greco-Roman national championship. He was the alternate for the 1996 Olympics and the 1997 World Championships.

Oostendorp is in his 22nd year as the head wrestling coach for Coe College in Cedar Rapids, Iowa. He is a three-time American Rivers Conference Coach of the Year and was named National Wrestling Coaches Association National Coach of the Year in 2009.

Oostendorp led the Kohawks to back-to-back fourth-place finishes at the 2008 and 2009 NCAA Championships, the two highest finishes in school history. He has guided Coe to 10 Top 10 finishes, including six trophy finishes, at the NCAA tournament. Oostendorp has coached seven national champions and more than 90 All-Americans during his career with the Kohawks.