The son of an American army doctor who was based in Germany after World War II, Shorter had early success with running. After winning the National Collegiate Athletic Association 6-mile run for Yale University in 1969, he won his first marathon in 1970 in São Paulo, Brazil. He followed that with a double victory in the 1971 Pan American Games, winning both the 10,000-metre run and the marathon.

At the 1972 Olympic Games in Munich, Shorter first competed in the 10,000 metres, placing fifth, but was dominant in the marathon, finishing 2 minutes ahead of the field in 2 hr 12 min 19.8 sec. His Olympic success was recognized with the Sullivan Award for the best American amateur athlete in 1972. At the 1976 Olympics in Montreal he earned the silver medal when he was upset by Waldemar Cierpinski of East Germany. Upon leaving competitive racing, Shorter founded a sportswear company, was a television sports commentator, and became involved in sports administration.