By Gina Pongetti Angeletti, MPT, MA, CSCS-ART,Cert. 

How does she do that? 

At the 2021 U.S. Classic, 2016 Olympic All-Around Champion and 25-time World Championships medalist Simone Biles performed a Yurchenko double pike, a skill that only a few men have even competed, becoming the first woman to perform or even attempt this skill in competition. 

The likes of LeBron James, Michelle Obama, Nadia Comaneci, and McKayla Maroney tweeted about how unbelievable the skill looked. Especially to the untrained eye. Those surrounding the sport have major respect for these feats, and those at home, well, they are just wondering if there was video editing or superhero movie magic involved!

The skill pushed the bar higher and heightened the conversation about the valuation of a vault that is no longer a “what if?” in women’s gymnastics. To push the sport forward, extraordinary efforts such as this need to be properly rewarded. Not only for Biles, but for those who come after her. 

With this achievement now marked in the history books (and countless media outlets throughout the world), we must acknowledge that the moving parts involved in this accomplishment, this vault, and its subsequent evaluation, are at best complex and must be examined. The evaluation of the skill, the risk versus reward, and the public’s role in cheering on superb, yet risky feats of difficulty, are all being called into question as part of the ongoing conversation surrounding the direction of the sport.

In 2019, a similar buzz surrounded Biles when she performed her double twisting double back tuck dismount off the balance beam at the World Championships in Stuttgart. Many speculated that the FIG, the international governing body of the sport of gymnastics, was attempting to control the reward and downplay the potential benefit in order to place a governor on the safety of these skills, by awarding the dismount a value lower than it deserved.

As it stands, so much conversation is circulating in the media as to the safety of performing skills such as Biles’ Yurchenko double pike. One can compare it to past buzz in pairs figure skating with throw triples, the speed of downhill skiing, tightrope walking, daredevil circus performers, aerial ski jumpers, and so many more. The more the risk, the greater the awe.

Common culture has also created and supported this dichotomy. People are concerned with the safety of contact sports such as hockey and football, yet parents weigh this risk-benefit and still enroll their kids. The world celebrates and wants bigger, higher and stronger; they want to see the envelope pushed with astonishing achievements even while knowing the potential outcomes and long-term effects. 

So, let’s break it down in terms of the code, the progressions and the physics. But first, let’s watch the vault itself!

Planning, Practice, Perfection and Performance 

The sport of gymnastics, as the code is built, rewards difficult skills by giving them a more advanced position in the alphabet, currently easiest (A) through most difficult (J) with an endless ceiling. The eventual difficulty ranking of the skill often combines difficulty of performance, fitness required to perform, comparison to prior skills that are lead-ups, and risk. 

There is a funny curve to this where gymnastics seems to value risk, to a point. When there is too high of inherent injury, skills are removed or banned, or even degraded to discourage their performance, or the risk-reward benefit. For example, the Thomas Salto, or tumbling ending in a roll-out, has been banned because of the injury risk and in some cases, as a response to injury. 

Because there is an “E” score (proper execution of the skill) and a “D” score (difficulty rating), the athlete and coaching staff need to weigh-in on when the increase in potential final score, which is a combination of the E and the D values, outweighs the risk of it either not being performed properly with too many deductions, or presenting too high of an injury jeopardy. 

As such, the science and the physics that go into the planning, practice, perfection and performance of gymnastics skills is quite extraordinary. We feel understanding the mechanics to perform a skill that reaches the pinnacle of human athletic achievement is important to examine.

First, there is so little time for decision-making in the middle of these spectacular skills because of how fast it all goes – the speed, the rotation, the flip, the transition, ultimately resulting in a commitment to the skill before the skill even begins. So essentially, the “if this, then this” theory is out the window. There is no time for perceiving, processing, and responding – the concept of a “reflex” in its true definition. There is no time to process what just happened before deciding what should happen next. For example, it is difficult to decide after blocking whether to completely invest in the skill and the energy it requires, or to bail safely. 

Second, there has to be trust in the process, routine after routine, training the body in a series of progressions and repetitions, that have to happen with no avail for decision-making time. To be successful, an athlete must advance these skills in a safe, carefully planned manner, varying landing surfaces that allow for a greater margin of error. 

This year has brought about the return of Chellsie Memmel, the 2005 World All-Around Champion and 2008 Olympic team silver medalist. At age 32, she has a different perspective on training than she did before marriage and two children (and a 9- year competitive hiatus)! She and her coach and father, Andy, weigh the risk of injury and her overall health in the orchestration of her routines. 

In November of 2020, when asked about constructing routines and planning new skills to acquire and old skills to re-acquire, Memmel explained, “We are working skill sets to see what’s going to fit. We are putting together the puzzle of what a routine should be and what could be easily competed, and then working toward getting those harder skills in there. In other words, what would be realistic to compete, not just what I can do!” 

In summary, the tighter the mind, the more focused the athlete. The more controlled the environment (mental and physical). The greater the proprioception and body awareness. In gymnastics, this all starts from the developmental point in training when the first vault block is taught. It is improved by ensuring that practicing and conditioning right, doing drills, and positioning right consistently, leads to the performance being right. It’s trust at its core.

So, what’s the point of reviewing all of this? We promise, there is one! It’s the physics lesson that you always (never) wanted. (Call that high school teacher and tell them thanks, what you taught me actually does have some application!)

When you watch elite competitions, you might think, “wow, how does she get that high?” or, “holy cow, she flipped so fast I couldn’t even count how many rotations there were!” The science behind this has to do with the physics of motion, the technology of the equipment, the reaction speed of the athlete and a little bit of luck. Let’s look at two key elements: reaction and procedural memory first.

As we mentioned, there is no time (or very, very little in the middle of most elite-level skills to react “in the moment.”) Response time is limited and is one of the contributing factors to the riskiness of the performance of skills. Of course, the faster the body is moving, the harder it is to stop the body in motion (we will address Newton’s law soon!). 

Because of this limited ability to react, athletes need to rely on training to make movements as memorized and natural, if you will, as possible. Thousands of repetitions, based on amazing preparation from basics to building into advanced skills, contribute to this process.  One of Vince Lombardi’s most famous quotes holds true here: “Practice doesn’t make perfect. Only perfect practice makes perfect.” 

Procedural memory, otherwise known as muscle memory, is a theory that explains how when motions or series of motions are repeated over and over again, the body learns these in sequence and can explain the perfection or improvement in motor skills. This applies as much to an infant as it does to an Olympian. Do you think about walking? Most likely unless you are 8 months old, the answer is no. Your body knows how to swing your arms, move legs, transition weight from left to right leg, front to back of the foot and more. This is often referred to as a predetermined way of responding, or anticipating response, without step by step feedback, but to the contrary, a pre-planned algorithm. 

In the case of Biles’ Yurchenko double pike there are three total flips, and a few places that can go wrong, to say the least: Run speed, hand placement for the roundoff, foot-landing position on the springboard, body vertical position–in relative–on the board, speed to the vault table, getting the hands back to the vault, the shoulders opened, the back arched -fast enough given the horizontal momentum, hand placement on the vault, friction of the surface to the hand, height, flipping speed, grip from hands to the legs to form the rotational velocity and tight pike position, air sense of when to prepare for landing, and the landing. 

From springboard to landing, from make it or break it, it’s 1.41 seconds. 

So, let’s talk about the variables that actually affect outcome, and examine each one as they relate to Simone’s vault and gymnastics skills overall.

The Brain

Prefrontal cortex, cerebellum and parietal cortex are the parts of the brain that contribute to processing. The cerebellum, specifically, does smoothness of motion and the timing of when things come before others, or in sequence. 

Timing of performance is key. As we noted about Biles’ vault, the whole process takes the same amount of time as the average adult’s single reaction time (which is 0.15 to 0.2 to one stimulus alone). This means that they receive stimulus from hearing, seeing, or feeling, and then create a response. 

In contrast to Single reaction time, Complex reaction time, is for certain not welcome in high level gymnastics. This is where you have many incoming stimuli to choose from, and you have to make educated decisions on which to respond to. Though more appropriate for gymnastics as a sport (with multiple stimuli), there is just no time for multiple choice answers. 

Hick’s Law essentially says that the more choices you have, the more likely you are to have a slower response time due to funneling through options. If one knows that the “block” before flipping happens to be off, there are quick choices to be made. Maybe their wrists were too flexed on the vault. Maybe the block sounded more like hands sliding and not a pop. Do they, then, turn it into a single, do a layout, pull hard if high enough, etc.? In hundredths of a second, how realistic is making that decision? 

The Body Position

So many variables go into the amazing feat of creating the space and time in the air to be able to perform the unimaginable. The run and steps have to be just right. The position of the body on the springboard needs to be exactly where the athlete needs it – not too vertical, not too hip flexed, feet exactly on the part of the springboard to give the most back to the athlete. The placement of the body, and the angle of impact, the openness of the shoulders and torso, the placement of the hands, the angle of the wrists all directly affect the transition of force, and whether an athlete will block enough to complete the skill and not land short. 

Coaches give feedback and instruction during conditioning to stay “tight” in the body, so that there is no give. This means, no bend in the shoulders, no slow-absorb in the elbows (small pushups), no buckle in the back or “arch,” prevented by keeping abdominals tight. This is because one wants there to be energy lost, if you will, and the force put into the vault to be given back to the athlete to make them go higher or transition this into rotational force. You get less height if you aren’t tight. If you go “slower” from the board to the vault table, you will most likely not go as high, either, because there is no force in to create force out. 

Proprioception, or knowing where your body is in space, is a key part of the feedback that automatically happens up the chain, or from body parts to the brain. The ankle usually responds, for example, to the outer ligaments feeling “stretching” or length, by saying, “uh oh, we may roll in or sprain.” With this new information, the muscles on the outside kick in to respond and prevent this from going any further. The reaction time depends on many things, including these variables: amount of repetitions practiced, basic strength, makeup of fast and slow twitch muscles, brain response training (speed of reaction time), hand-eye coordination, proprioception, etc. 

The elite-level athlete, therefore, should be able to respond faster, more accurately. For Biles’ vault, again as an example, how her wrists are flexed, or pressure on her shoulders, may give her suggestive feedback as to how high she will be and how to adjust if possible. They also know sooner if the environment is off. Examples of this are: my hands slipped or are slipping; I came on to the vault too high; I did not block high enough. Recognizing this should allow the athlete to safely adjust what comes next (pull harder) or pull “out” of a skill, doing a timer, or purposely balking. 

Friction

Let’s assume the preflight goes well. The contact with the board is perfect. The hands hit the vault, and there is a slip. Maybe a quarter of an inch, maybe a millimeter. How much is too much? Physics will tell you that any contact alteration will directly influence the quality of force that is lost. In this split second, the athlete has to decide whether to continue the pre-planned path or not. At times, there is more risk in balking that there is in pulling harder, pending many things. The keen sense that the experienced, elite athlete has to know, exactly how high they are off of the table and the speed of flip or rotation, is fine-tuned and is different in magnitude for each athlete. 

FIG has equipment mandates, or apparatus norms, for the surface make-up of each surface an athlete comes in contact with. This includes the covering on the vault table, balance beam, the rebound rating of the foam and springs in the floor. Friction, however, is a product of what comes in contact with it. Chalk, honey, spit (I know, but it happens), sugar water, the makeup of the leather of the grip, all are ways the athlete adjusts their “stickability” to a surface. Increasing the coefficient of friction will allow for more energy transition. 

Doubt 

Young and inexperienced athletes often experience phases of fear in the sport, which often result in doubt or a lack of confidence going into learning or performing a skill. Even the best gymnasts in the world have experienced this phenomenon. At times, this is because of a lack of preparation, mentally and physically, a lack of lead-up skills, numbers performed, watching another athlete fall or get injured, or just even a lack of confidence in one’s self. The elite athlete trains with such numbers, and such past success, that their confidence should be based in part because of a history of repetitive success. 

The trust in one’s coach and the respect for their opinion (i.e. you are ready to take this to high beam, let’s flip today, you can do this without spot or matting, etc.) plays into the level of confidence the athlete has. This has to be present in order to perform some of the world’s most difficult skills in any sport. A developmental gymnast can say “split, then step down, lift arms, square hips” for a simple handstand step-down. An elite cannot wait to flip, or initiate flipping, when planning a Yurchenko pike single let alone a double. The more flipping and twisting, the harder the skill, the higher the velocity or rotational velocity, the less room there can be for doubt, mistakes, or even equipment malfunction.

Physics

Now for the best part! Let’s nerd out on a concept called Linear Kinematics which is the culmination of the pattern, the form and the sequence of movement over time. This is important as we look at the risk of the skill in relation to what observers see as speed, how much actually happens over a period of time, on top of the concept of sequencing that we have already touched on. 

The speed that is applicable in gymnastics is called velocity, which has a direction and a magnitude. We look at horizontal (side to side) and vertical (up and down) velocities. The speed of the run creates horizontal velocity. It can be changed vertically, by means of an object changing its path (hands hitting the vault for example). This turns into angular velocity, depending on the contribution of each, and their ratio. And, thus, you have the Pythagorean Theorem. Remember that? 

Of course, all of this is complicated (or made more interesting, depending upon your point of view) by things like friction, energy transfer (if the body is loose, elbows bent, shoulders soft, etc.). There are forces inside and outside of the body, or internal and external forces. External forces are, truly, what make gymnastics different now than years ago- springs that can store and give more energy, the density of the foam, spring in a bar, rebound of the vault table, etc.  The difference between gymnastics when Natalia Yurchenko originally performed the namesake vault in 1982 (a single flip) is a mountain of advances in equipment. Even she is in awe of adding a second flip. 

There is a “flight path,” or curve, that the athlete takes after they leave the object that changes their direction, for example to make running velocity and springs in the vault turn into a curve that goes up and then comes down. Add in rotation, and we refer to it as angular movement (speed or velocity). We can consider the vault block that will potentially be affected by Newton’s Law (the first) as well (objects keep moving unless something makes that different). 

With good friction, as we spoke of earlier, motion can be changed, and the energy lost minimized. If hands slide or slip, motion stays in that direction (i.e. linear with some vertical and a touch of rotation in vault pre-flight and at impact of hands to the vault table) then less motion will be transferred to vertical. Thus, not enough height to make a double pike. 

Jade Carey, Senior National Team Member and Tokyo contender, is also tempting physics this week in Fort Worth by  planning to perform a triple twisting laid out double backflip on floor, from a roundoff back handspring takeoff, after a few simple steps of a run.

The position of the back handspring when she takes off is purposeful. For a triple twist with a single flip, the athlete wants to take horizontal velocity and change that into vertical velocity. The more twists there are, the higher the degree of angle on takeoff. One flip, three twists. They will take off at a negative angle relative to vertical. For Jade, she has the nearly impossible charge of flipping two times, twisting three times, and not doing too much of either. This would result in over-flipping (missing her feet and falling to back or even more) or over or under-twisting (knee and ankle purgatory). She is close to vertical upon setting as she needs the height, and time to flip. 

The craziest part are the athletes who are trained so highly that they can perform a triple twist, a double layout, a double-double and a triple-double – all skills that require such fine tuning. Changes between each are so minute that confusion is a concern. The angular momentum (direction) and the angular velocity may be in different planes of motion. All with such subtle changes in angular and rotational velocity, take off angle and organization of the order of magnitude of each, that hundredths of a second make a difference. Twisting at a certain velocity versus flipping at a different one. Again, with such marginal room for error. 

At the end of the day, the respect due to the athletes and the coaches who guide them through these feats is astonishing. The hours of preparation and repetition are unfathomable. When the art and science of sport come together, anything is possible.

Photos by Lloyd Smith for Inside Gymnastics

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