Editing Figure skating jumps (section)

==Execution==
According to Kestbaum, jumps are divided into eight parts: the set-up, load, transition, pivot, takeoff, flight, landing, and exit. All jumps, except for the Axel, are taken off while skating backward; Axels are entered into by skating forward.{{Sfn|Kestnbaum|2003|p=27}} Skaters travel in three directions simultaneously while executing a jump: vertically (up off the ice and back down); horizontally (continuing along the direction of travel before leaving the ice); and around.{{Snf|Kestnbaum|2003|p=282}}{{Snf|Cabell|Bateman|2018|p=21}} They travel in an up and across, arc-like path while executing a jump, much like the projectile motion of a [[pole vault|pole-vaulter]]. A jump's height is determined by vertical [[velocity]] and its length is determined by vertical and horizontal velocity.{{Snf|Cabell|Bateman|2018|p=19}} The trajectory of the jump is established during takeoff, so the shape of the arc cannot be changed once a skater is in the air.{{Snf|Cabell|Bateman|2018|p=20}} Their body absorbs up to 13–14 [[g-forces]] each time they land from a jump,{{Snf|Cabell|Bateman|2018|p=35}} which sports researchers Lee Cabell and Erica Bateman say contributes to overuse injuries and stress fractures.{{Snf|Cabell|Bateman|2018|p=38}}

Skaters add variations or unusual entries and exits to jumps to increase difficulty. For example, they will perform a jump with one or both arms overhead or extended at the hips, which demonstrates that they are able to generate rotation from the takeoff edge and from their entire body instead of relying on their arms. It also demonstrates their back strength and technical ability to complete the rotation without relying on their arms. Unusual entries into jumps demonstrate that skaters are able to control both the jump and, with little preparation, the transition from the previous move to the jump.{{Snf|Kestnbaum|2003|p=27}} Skaters rotate more quickly when their arms are pulled in tightly to their bodies, which requires strength to keep their arms being pulled away from their bodies as they rotate.{{Snf|Cabell|Bateman|2018|p=22}}

According to Deborah King and her colleagues from [[Ithaca College]], there are basic physics common to all jumps, regardless of the skating techniques required to execute them.<ref name="tanyalewis" /> Factors such as [[angular momentum]], the [[moment of inertia]], [[angular acceleration]], and the skater's [[center of mass]] determines if a jump is successfully completed.<ref name="evelynlamb"/>{{Snf|Cabell|Bateman|2018|p=27}} Unlike jumping from dry land, which is fundamentally a linear movement, jumping on the ice is more complicated because of angular momentum. For example, most jumps involve rotation.{{Snf|Petkevich|1988|p=193}} Scientist James Richards from the [[University of Delaware]] says successful jumps depend upon "how much angular momentum do you leave the ice with, how small can you make your moment of inertia in the air, and how much time you can spend in the air".<ref name="evelynlamb">{{cite news |last1=Lamb |first1=Evelyn |date=7 February 2018 |title=How Physics Keeps Figure Skaters Gracefully Aloft |work=[[Smithsonian (magazine)|Smithsonian]] |url=https://www.smithsonianmag.com/science-nature/how-physics-keeps-figure-skaters-gracefully-aloft-180968051/ |access-date=21 July 2022 |archive-date=31 January 2021 |archive-url=https://web.archive.org/web/20210131022223/https://www.smithsonianmag.com/science-nature/how-physics-keeps-figure-skaters-gracefully-aloft-180968051/ |url-status=live }}</ref> Richards found that a skater tends to spend the same amount of time in the air when performing triple and quadruple jumps, but their angular momentum at the start of triples and quadruples is slightly higher than it is for double jumps. The key to completing higher-rotation jumps is how they control the moment of inertia. Richards also found that many skaters, although they were able to gain the necessary angular momentum for takeoff, had difficulty gaining enough rotational speed to complete the jump.<ref name="evelynlamb"/> King and her colleagues agree, saying skaters must be in the air long enough, have enough jump height to complete the required revolutions, and the amount of vertical velocity they are able to gain as they jump off the ice, although different jumps require different patterns of movement. Skaters performing quadruple jumps tend to be in the air longer and have more rotational speed. King also found that most skaters "actually tended to skate slower into their quads as compared to their triples",{{Sfn|King|Smith|Higginson|Muncasy|2004|p=120}} although the differences in the speed in which they approached triples and quadruples were small. King conjectured that slowing their approach into the jumps were due to skaters' "confidence and a feeling of control and timing for the jump",{{Sfn|King|Smith|Higginson|Muncasy|2004|p=120}} rather than any difference in how they executed them. Vertical takeoff velocity, however, was higher for both quadruple and triple toe loops, resulting in "higher jumps and more time in the air to complete the extra revolution for the quadruple toe-loop".{{Sfn|King|Smith|Higginson|Muncasy|2004|p=120}} As Tanya Lewis of ''[[Scientific American]]'' puts it, executing quadruple jumps, which as of 2022, has become more common in both male and female single skating competitions, requires "exquisite strength, speed and grace".<ref name="tanyalewis" />[[File:Ando 2009 Worlds SP.jpg|left|thumb|Japanese figure skater [[Miki Ando]], first female skater to land a quadruple jump, in 2009]]
[[File:Ilia Malinin 2022 Skate America Short Program 1.jpg|left|thumb|American [[Ilia Malinin]], the first skater to successfully complete a quad Axel in competition, in 2022 ]]
For example, a skater could successfully complete a jump by making small changes to their arm position partway through the rotation, and a small bend in the hips and knees allows a skater "to land with a lower center of mass than they started with, perhaps seeking out a few precious degrees of rotation and a better body position for landing".<ref name="evelynlamb" /> When they execute a toe jump, they must use their skate's toe pick to complete a pole-vaulting-type motion off the ice, which along with extra horizontal speed, helps them store more energy in their leg. As they rotate over their leg, their horizontal motion converts into tangential velocity.<ref name="tanyalewis" /> King, who believes quintuple jumps are mathematically possible, says that in order to execute more rotations, they could improve their rotational momentum as they execute their footwork or approach into their takeoff, creating torque about the rotating axis as they come off the ice. She also says that if skaters can increase their rotational momentum while "still exploding upward"<ref name="tanyalewis" /> they can rotate faster and increase the number of revolutions they perform. Sports writer Dvora Meyers, reporting on Russian coaching techniques, says female skaters executing more quadruple jumps in competition use what experts call pre-rotation, or the practice of twisting their upper bodies before they take off from the ice, which allows them to complete four revolutions before landing. Meyers also says the technique depends on the skater's being small, light, and young, and that it puts more strain on the back because they do not use as much leg strength. As a skater ages and goes through puberty, however, they tend to not be able to execute quadruple jumps because "the technique wasn't sound to start with".<ref name="dvorameyers" /> They also tend to retire before the age of 18 due to the increase of back injuries.<ref name="dvorameyers" />

Since the tendency of an edge is toward the center of the circle created by that edge, a skater's upper body, arms, and free leg also have a tendency to be pulled along by the force of the edge. If the upper body, arms, and free leg are allowed to follow passively, they will eventually overtake the edge's rotational edge and will rotate faster, a principle that is also used to create faster spins. The inherent force of the edge and the force generated by a skater's upper body, arms, and free leg tend to increase rotation, so successful jumping requires precise control of these forces. Leaning into the curvature of the edge is how skaters regulate the edge's inherent angular momentum. Their upper body, arms, and free leg are controlled by what happens at the time of preparation for the jump and its takeoff, which are designed to produce the correct amount of rotation on the takeoff. If they do not have enough rotation, they will not be at the correct position at the takeoff; if they rotate too much, their upper body will not be high enough in the air. Skaters must keep track of the many different movements and body positions, as well as the timing of those movements relative to each other and to the jump itself, which requires hours of practice but once mastered, becomes natural.{{Snf|Petkevich|1988|pp=193–194}}

The number of possible combinations jumps are limitless; if a turn or change of feet is permitted between combination jumps, any number of sequences is possible, although if the landing of one jump is the takeoff of the next, as is the case in loop combinations, how the skater lands will dictate the possibilities going into subsequent jumps. Rotational momentum tends to increase during combination jumps, so skaters should control rotation at the landing of each jump; if a skater does not control rotation, they will over-rotate on subsequent jumps and probably fall. The way skaters control rotation differs depending upon the nature of the landing and takeoff edges, and the way they use their arms, which regulate their shoulders and upper body position, and free leg, which dictates the positioning of their hips. If the landing on one jump leads directly into the takeoff of the jump that follows it, the bend on the landing leg of the first jump serves as preparation for the spring of the takeoff of the subsequent jump. If some time elapses between the completion of the first jump and the takeoff of the subsequent one, or if a series of movements serve as preparation for the subsequent jump, the leg bend for the spring can be separated from the bend of the landing leg.{{Sfn|Petkevich|1988|pp=271–272}}