the 20th century, well after the establishment of organized skating competitions, when jumps with the potential of being completed with multiple revolutions were invented and when jumps were formally categorized. These jumps became elements in athletic free skating programs, but they were not worth more points than no-revolution jumps and half-jumps. In the 1920s Austrian skaters began to perform the first double jumps in practice and refine rotations in the Axel. Skaters experimented with jumps, and by the end of the period, the modern repertoire of jumps had been developed. Jumps did not have a major role in free skating programs during international competitions until the 1930s. Athleticism in the sport increased between the world wars, especially by women like Norwegian world and Olympic champion Sonia Henie, who popularized short skirts which allowed female skaters to maneuver and perform jumps. When international competitions were interrupted by World WarII, double jumps by both men and women had become commonplace, and all jumps, except for the Axel, were being doubled. According to writer Ellyn Kestnbaum the development of rotational technique required for Axels and double jumps continued, especially in the United States and Czechoslovakia. Post-war skaters, according to Hines, "pushed the envelope of jumping to extremes that skaters of the 1930s would not have thought possible". For example, world champion Felix Kasper from Austria was well known for his athletic jumps, which were the longest and highest in the history of figure skating. Hines reported that his Axel measured four feet high and 25 feet from takeoff to landing. Both men and women, including women skaters from Great Britain, were doubling Salchows and loops in their competition programs. During the post-war period, American skater Dick Button, who "intentionally tried to bring a greater athleticism to men's skating", performed the first double Axel in competition in 1948 and the first triple jump, a triple loop, in 1952. Triple jumps, especially triple Salchows, became more common for male skaters during the 1950s and early 1960s, and female skaters, especially in North America, included a full repertoire of two-revolution jumps. By the late 1960s and early 1970s, men commonly performed triple Salchows and women regularly performed double Axels in competitions. Men would also include more difficult multi-revolution jumps like triple flips, Lutzes, and loops; women included triple Salchows and toe loops. In the 1980s men were expected to complete four or five difficult triple jumps,