Pair skating, along with men's and women's single skating, has been an Olympic discipline since figure skating, the oldest Winter Olympic sport, was introduced at the 1908 Summer Olympics in London. The ISU World Figure Skating Championships introduced pair skating, along with women's singles, also in 1908. Hübler and Burger were the first Olympic gold medalists in pair skating in 1908; they also won the 1908 and 1910 World Championships. In 1936, Maxi Herber and Ernst Baier won the gold medal at the Olympics and went on to win the World Championships from 1936 to 1939. The first pair skating national competitions in Canada occurred in 1905 and the first time pair skating was included during a U.S. Championships was in 1914, but there are only a few descriptions of pair skating in North America before World War I. Side-by-side skating, also called shadow skating, in which partners executed the same movements and steps in unison, were emphasized in the early 1920s. Pair skating became more athletic in the 1930s; partners executed "a balanced blend of shadow skating coupled with increasingly spectacular pair moves, including spins, death-spirals, and lifts". Hines credits German pair skaters Maxi Herber and Ernst Baier and French team Andrée Brunet and Pierre Brunet with developing athletic elements and programs that included pair spins, side-by-side spins, lifts, throw jumps, side-by-side jumps, and side-by-side footwork sequences. By the 1930s, pair skating had advanced; Hines stated, "It was not yet viewed equally with singles skating, at least from a technically standpoint, but it had grown to be a much-appreciated discipline". Hines also reported that many single skaters during the era also competed in pair skating.