Born in Cologne, Frodeno started out as a swimmer in South Africa at the age of 15, and he entered triathlon in 2000. He then went to Germany to compete in the Triathlon-Bundesliga, and qualified for the national team in 2002. As part of the national team he trained at the Olympic Training Centre in Saarbrücken. Before his Olympic victory, his best result was placing sixth in the 2007 World Championships, and winning the German Championship the same year. He had previously also placed second and third in various races of the World Cup from 2005 to 2008.