Heymans has represented Namibia numerous times, including at the 1991, 1995, 1999 and 2003 All-Africa Games. He also competed for his country at the 1994, 1998, 2002 and 2006 Commonwealth Games. As for the Summer Olympics, Heymans has participated in the 2000, 2004 and 2008 Summer Olympics. In the 2008 games, Heymans was the country's flag-bearer at the opening ceremonies. Heymans won the inaugural Transalp Mountain Bike stage race in 1998 and then the first Absa Cape Epic in 2004.