Otto Breg started out as a weighlifter. He collected various medals at Austrian championships, including the 1974 overall title. He then switched to being a bobsleigh runner. As a member of the four man sled, he won a second national title in this sport, and represented Austria at international championships. His most notable result was a 6th place in the 1976 Olympics, in the sled piloted by Werner Delle Karth. Breg later owned a bureau for electrotechnical engineers in Braunau am Inn, and was involved in local roller hockey and motor sport clubs.