A jump combination, defined as "two (or more) jumps performed in immediate succession", is executed when a skater's landing foot of the first jump is also the take-off foot of the following jump. The limitation on the number of jumps skaters can perform in their programs, called the "Zayak Rule" after American skater Elaine Zayak, has been in effect since 1983, after Zayak performed six triple jumps, four toe loop jumps, and two Salchows in her free skating program at the 1982 World Championships. Writer Ellyn Kestnbaum stated that the ISU established the rule "in order to encourage variety and balance rather than allowing a skater to rack up credit for demonstrating the same skill over and over". Kestnbaum also stated that as rotations in jumps for both men and women have increased, skaters have increased the difficulty of jumps by adding more difficult combinations and by adding difficult steps immediately before or after their jumps, resulting in "integrating the jumps more seamlessly into the flow of the program".