An investigation into the physics behind figure skating and sports safety.
By Aishwarya Manoj
The year is 2018, and Olympic figure skater Nathan Chen has just set an Olympic record by completing five quadruple jumps at the Pyeongchang Winter Olympics. Skating fans are thrilled by the recent developments in the sport, but many begin to wonder if these successes in the field indicate that a quintuple jump may one day be landed in competition.
The difference between a quadruple and quintuple jump comes down to the number of rotations a skater completes while in the air. A quadruple jump requires a skater to complete four revolutions, whereas the fabled quintuple jump requires skaters to complete five.
Olympic figure skater Shoma Uno said he believed it would be possible for humans to accomplish the quintuple jump because of the similar discussion surrounding the quadruple jump in the past. Uno claimed that there was once contention surrounding the completion of a quadruple jump in competition, but the move has become somewhat commonplace over the years.
However, the question still remains: is a quintuple jump physically possible?
The Physics Behind It
Before diving into the physics behind a quintuple jump, a brief discussion of the physics of rotations is necessary. Torque can be thought of as a force that causes rotation, whereas the moment of inertia can be thought of as a value akin to mass that also relies on the distribution of mass. Angular velocity is a measure of the speed and direction in which an object rotates and angular momentum is the product of the moment of inertia and angular velocity.
In rotational motion, angular momentum is conserved as long as there are no external torques acting on a system. When a figure skater jumps, they are able to use the amount of angular momentum they have in order to execute their desired move. Skaters can often increase their angular momentum during takeoff before jumping.
MVHS junior Sophia Chen recounts her experience preparing for jumps as a figure skater.
“To get enough rotations [it requires] so much effort [from your body because] you have to prepare the jump,” Chen said. “Your body needs to be at a correct angle in order for you to take off and [be able] to rotate as many turns as you want [since you’re] defying gravity.”
MVHS junior Anika Mishra has found that there are ways to quickly gain velocity while on the ice.
“There’s a certain motion [you have] to do with your feet,” Mishra said, “[If] you put a little more weight and force when [you are] trying to pick up your foot, it helps you go faster.”
Skaters need enough angular momentum while in the air to allow them to complete spins. If a skater does not have a desired amount of angular momentum, they can decrease their moment of inertia by pulling their arms in, and thus increase their angular velocity. This allows skaters to complete more rotations with a given amount of angular momentum.
Astrophysicist Sabrina Stierwalt writes that a quadruple jump would require skaters to have an angular velocity of around 340 revolutions per minute, whereas a quintuple jump would require speeds closer to 500 revolutions per minute. This drastic difference is what causes people to debate the plausibility of landing a quintuple jump.
Athletic Trainer Javier Margarito discussed his views on the topic. “[Eventually], the sport [will have] to be analyzed [to discover] what can be improved. [For] example, [can] you make [the ice] less resistant to the ice skate?” Margarito said. “[But] you start [to wonder] how much of that is mechanical versus actual human endeavor.”
The Implications
Despite the allure of quintuple jumps and other figure skating moves that require many rotations, athletes such as Uno acknowledge the physical toll the sport can take on their bodies. Landing figure skating jumps exerts a great amount of force on an athletes body, often causing injuries in their joints.
As Debora King, a professor of exercise science and athletic training who specializes in the Biomechanics of Human Movement told The Daily Beast, “‘Overuse injuries come from too much load and not enough recovery time. [You] can get into a cycle where [muscle] continues to break down, particularly in the knee, lower leg, ankle, and foot.’”
“One of my coaches [had] a hip replacement because he was a professional figure skater,” Chen said. “ [He] was probably attempting jumps, because [they are very risky]. You spin through the air several times and you have to land on one foot. [It hurts more] if you [don’t fall] on your feet.”
Margarito also discussed injuries in the field of skating. “[In] figure skating, you see a lot of falls, [especially] on your rear end,” Margarito said. “[So] it stands to reason that [you will] eventually [bruise] or potentially break your tailbone. That’s [an injury that is] unique to figure skating.”
More rotations require higher jumps, resulting in the force exerted on skaters being equivalent to about three to five times their weight. King also told Science Friday that a skater landing “[would] be like slamming on your brakes to come to a stop at 60 miles per hour… [it takes a lot of force because] they come to a stop very quickly.”
And skaters experience this force frequently as they train heavily in order to perfect their jumps.
“[We] try to practice rotating twice or three times off-ice because if you can do that off-ice then you can [do it] on ice,” Chen said. “[We would] practice jumping up and down, then [jumping] up [and rotating] once, and then [rotating] twice [and rotating] three times.”
To combat the taxing aspects of their sport, skaters make an effort to minimize injury and protect their bodies.
“One of the biggest things they teach you in ice skating [is] how to fall [properly],” Mishra said. “[If] you properly fall and [tie] your shoes on [tight] so that your ankle is secure, [you are] less prone to injuries.”
The Consensus
Understanding the physics behind rotations and the toll skating takes on athletes leads to greater discussion about sports safety and precautions athletes must take in order to remain safe while on the ice. These lessons are fundamental to maintaining the safety of athletes as they continue to strive to accomplish difficult feats. So, will the quintuple jump someday be completed? Only time will tell.
Res Novae 