Canoe sprint has been part of the Olympic Games since 1936 (Berlin) for men, and since 1948 (London) for women. Notable Olympic gold medal winners are Birgit Fischer-Schmidt (eight gold medals between 1980 and 2004) and Gert Fredriksson (six gold medals between 1948 and 1960). Canoe sprint takes place on a straight course divided in lanes, on calm water. The distances recognised by the ICF for international races are 200 m, 500 m, and 1000 m. Each boat has its own designated lane, except for races over more than 1000 m, where there also may be turning points. Men race in canoes and in kayaks, women in kayaks except in Canada and the United States where women's canoe is an event raced at both Canada Games and National Championships. For each race a number of heats, semi-finals and a final may be necessary, depending on the number of competitors.