This article is a modification of a similar one published in Prassas, S. & Gianikellis, K. (Eds.) (2002). Applied Proceedings of the of XX International Symposium on Biomechanics in Sports-Gymnastics. Department of Sport Science, University of Extremadura, Cáceres, Spain

Introduction

One might wonder why—even after hundreds and hundreds of repetitions—the chances of any gymnast consistently executing, without errors, difficult vaults such as the one depicted in the posted video are minuscule? Shouldn’t vaulting be the “easiest” among the apparatuses on which gymnasts compete? After all, what a competitor has to do is sprint down the runaway, takeoff from a springboard, touch the vaulting table with his/her hands, and execute “only one” skill. “Only one”, however is a curse as much as a blessing. If you miss the “one skill”, your chances of winning are all but guaranteed to vanish, for the one skill performed in vaulting is worth as many points (up to ten) as the sum of all skills comprising a routine in each of the other apparatuses.

Most gymnasts currently compete in three basic families of vaults. In (front) handspring type of vaults, gymnasts takeoff and maintain a square body configuration throughout the pre-flight and vaulting table support (Figure 1). In the Tsukahara family, gymnasts execute up to a half turn during pre-flight and contact the vaulting table one hand at a time (Figure 2). Yurchenko’s, which have become increasingly more popular, are round off entry vaults where the gymnast leaves the springboard rotating backwards (Figure 3). All vaults include the following elements:

The Sprint

In recognizing the importance of this aspect of vaulting in providing the majority of the energy required for the successful completion of a vault, coaches frequently advise/coerce their gymnasts to “run harder”. In spite of this, apart from qualitative observations, there is limited data on this aspect of vaulting. Based on available information, the following observations may be helpful:

Springboard Phase

During this phase of vaulting, the kinetic energy generated during the sprint/pre-vaulting table motion is transformed into appropriate linear and angular components. Figure 4 presents body position and mechanical variables from board contact to takeoff for a typical (front) handspring type of vault.

During the springboard phase the following variables define the gymnast’s motion:

At board contact (A, Figure 4), gymnasts lean backwards from the vertical position and begin pivoting over their feet until takeoff (B, Figure 4). Data from the literature suggest that in both, handspring and Tsukahara vaults gymnasts lean back about 30 degrees from the vertical axis. There is no similar data for Yurchenko vaults, but the round off entry dictates the body contact angle. The function of the board reaction force, F, as well as the time that force acts is to modify both the linear (M) and angular (L) momentum of the gymnast. The net horizontal component of that force is opposite to the direction of motion resulting in a net loss of horizontal velocity and the generation of angular momentum (L1). The vertical component initially decreases the (downward) vertical velocity and subsequently generates the upward velocity. With regard to rotation, the vertical force promotes angular momentum only when the center of mass (CM) passes over the base of support (feet). It should be noted that:

Pre-Flight Phase

The pre-flight phase of the vault is governed by the projectile and angular variables at the completion of the springboard phase of vaulting (B, Figure 4) as described above. It should be noted that, although the gymnast may make adjustments for less than optimum spring board to vaulting table distance, he/she may do so at the expense of breaking form and/or taking off from an area of the spring board which may not be optimum for full utilization of its elastic properties.

Vaulting Table Support Phase

The vaulting table support phase can be subdivided into an initial blocking or absorbing phase and a push off or repulsion phase. The initial linear and angular conditions and the actions of the gymnast during both the absorption and repulsion phases determine whether the gymnast may depart from the vaulting table with the required linear and angular momentum requirements to complete the intended vault.

Figure 5 presents schematics of this phase including:

As indicated above, contact mechanical variables (C, Figure 5) are the result of various combinations of the projectile variables, the angular momentum at springboard takeoff, and the springboard-vaulting table distance. During the brief time of board contact, the gymnast first is “compressed” by an amount proportional to the observed radial velocity and subsequently, if there is sufficient interaction between the gymnast and the vaulting table, “elongates” as he/she pushes against it. The vaulting table reaction force (F) acts on the gymnast in a similar manner as the springboard reaction force described in the springboard phase above.

A few studies, however, indicated that it is within a gymnast’s capability to increase angular momentum during this phase. This would require a slightly different body configuration—greater shoulder joint extension and a smaller hip joint angle—at vaulting table contact (C, Figure 4) as well as higher angular velocity at vaulting table impact.

Post-Flight Phase

The post-flight phase of the vault is governed by the projectile and angular variables at the completion of the push off vaulting table support phase (D, Figure 5). During this phase:

With respect to the relationship between takeoff angular momentum and the somersaulting/twisting actions in post flight, it should be noted that the preferable mechanism to generating twist(s) is through asymmetrical motion of the arms after leaving the vaulting table. Although other twisting techniques may be applied, this technique may be preferable since it can be removed before landing by reversing the arm action ensuring, thus, a more stable landing.

Landing

The landing phase of a typical forward translating forward rotating (e.g. handspring front somersault(s)) vault is depicted in Figure 6. As The variables dictating the success or failure of the landing are:

Data from the 2000 Olympics indicate overwhelmingly that the majority of both male and female gymnasts fail to “stick” the landing in vaulting. The same data indicate that more gymnasts over rotate than under rotate and that female gymnasts fair worse than males. Lastly, this data reveals that, in both sexes, forward translating/forward rotating vaults are the most difficult to control. An explanation of some of the reasons of why it is difficult to consistently “stick” landings has been offered in a previous paper and is adapted for the landing depicted in Figure 6.

Lets first assume that Figure 6 is a depiction of the landing phase of a handspring double front somersault—currently one of the most difficult vaults. A skill such as this requires that the gymnast take-off from the vaulting table with a large amount of somersaulting angular momentum (L3, Figure 5). Due to the momentum conservation principle, the gymnast’s angular momentum at touchdown (L4, Figure 6) will be the same as L3. L4 is reduced after touchdown due to the angular impulse from the floor. Angular impulse is the product of torque and the time the torque acts. Torque, in turn, is the product of force and its perpendicular distance from the axis of rotation. In equation form, this relationship—known otherwise as the Impulse-Momentum relationship—is expressed as:

It is an extremely difficult task to generate/withstand the high ground reaction forces generated at impact and to time to land with an “optimum” perpendicular CM-to-feet distance (d, Figure 6).

It should be mentioned that before the gymnast takes these step(s), he/she might attempt other corrective actions—such as rotating the arms in the same or opposite direction as body rotation and/or flexing the hips and/or knees. The first action is based on the conservation and “transfer” of angular momentum principles. If these principles are successfully applied, the body rotation may increase in the desired direction, may decrease, or even reverse thus enabling the gymnast to avoid the fall/step(s) described previously. The second action—flexing the hips and/or knees—is based on the gymnast attempting to increase the time interval for landing and, thus, the ground impulse which brings the body to rest.

The same principles apply to vaults where the gymnast lands facing the vaulting table (as in Figures 2 and 3). As reported in this web-site, the higher landing success rate for these type of vaults may be attributed to the gymnasts’ ability to get kinesthetic feedback, or visually “spot” the mat, and make necessary adjustments earlier than in forward rotating vaults (see also other articles on this site: 1, 2).

Finally, the difficulties in sticking landings in vaulting are multiplied when rotation(s) about the longitudinal axis are added to the vault. These difficulties are linked to the associated actions necessary to remove the twisting before landing and exaggerated when the twisting has to be stopped after touchdown.

Conclusion

Success in vaulting depends on a multitude of variables, some independent and some within a gymnast’s control. Generally:

With the understanding that all phases of vaulting, beginning with a short sprint and ending with landing, are important and inter-related, Figure 7 loosely presents a schematic of the factors that determine the post-flight score, which, from a judging point of view, contributes the most to the total score. Obviously, a model encompassing all aspects of vaulting would be much more chaotic/difficult to put it into perspective and understand. The good thing is that gymnasts do not have to think of these schematics—they “only” have to execute!

Suggested Readings