between World War I and World War II. The spins performed by Norwegian skater Sonja Henie, which can be viewed in her films made during the 1930s, often reached 40 or more revolutions and were "usually well-centered, fast, and as exciting to watch today as they were then". By the late 1930s, all three basic spin positions were used. Skaters were expected to spin in both directions at the time, but as spins became faster and more difficult, they were only expected to spin in one direction. Skaters like American Ronnie Robertson in the 1950s, Swiss Denise Biellmann in the 1980s, and Swiss Lucinda Ruh in the 1990s, had "an uncanny ability to perform spins", and were sometimes able to execute up to seven revolutions per second in the upright position. Canadian figure skater Olivia Oliver holds the Guinness World Record for the fastest spin, 342 rotations per minute, which she completed in Warsaw in 2015. However, as researchers Lee Cabell and Erica Bateman stated in 2018, "Unfortunately, modern figure skaters often do not achieve these types of revolutions because the rules require skaters to perform spins in different body positions". World champion and commentator Scott Hamilton reported that Robertson would spin so fast that he would break blood vessels in his hands. Hamilton also stated that Robertson and Ruh were so good at executing spins that they "would find that part of the blade that had no friction with the ice, and they would spin at the same speed forever. It just seemed like it would never end, and they could change positions and then recrank the spin and make it happen again". Ruh, however, suffered from chronic nausea and dizziness, and would regularly lose consciousness during practices or in hotel rooms. She was eventually diagnosed with miniconcussions that were probably linked to executing spins and the forces generated by them, especially during layback spins. Ruh also later stated that the rotational speeds she was able to maintain and the long hours practicing and performing them most likely contributed to the severity of her injuries. Pair spins became part of competitive figure skating between the world wars; side-by-side spins, along with death spirals, lifts, throw jumps, side-by-side jumps, and side-by-side footwork sequences, were a part of pair skating by the 1930s. In ice dance, there were limitations to dance spins, as well as for other moves associated with pair