As Movement Specialist at the Western Australian Institute of Sport, I’m fortunate to work with some of the best pole vaulters in the world and their expert coaches. I remember my first session with them at the track and being taken aback as I stood alongside the runway and Kurtis Marschall effortlessly soared over a 5.20 m bar from a casual 8-step run up. Well, it appeared effortless and casual but of course it’s not! I soon came to understand how complex and demanding the event is, working with Kurtis, Nina Kennedy and others, in the lead up to the Paris Olympics. This post describes the fundamental mechanics of pole vaulting as well as some of the more peculiar elements of athlete-pole interaction that make this sport so unique.
Expert performance in the pole vault is a spectacle to behold. It requires a wondrous combination of physical prowess, technical excellence and mental fortitude. Fundamentally, though, pole vaulting is an exercise in mechanical energy generation and transformation. This makes it not only a captivating event to observe as a spectator, but also an intriguing one to analyse as a biomechanist.
Maximum energy
Athletes aim to produce the maximum potential energy at the apex of the jump through a sequence of manoeuvres and utilisation of a flexible pole. The sequence starts with the run up where the athlete generates kinetic energy (a function of their body mass and velocity). After take-off, their kinetic energy initially decreases while potential energy (a product of their mass, height above the ground, and gravity) increases as they rise into the air. The pole’s contribution to performance occurs through elastic energy storage as it bends, which is then returned to the athlete as it straightens. Expert pole vaulters achieve an overall energy gain in the athlete-pole system from take-off until maximum pole bend (MPB) (that is, more energy is stored in the pole than is lost by the athlete), and further energy gain during pole straightening (the increase in athlete energy is greater than the decrease in pole energy).
Figure 1. Athlete, pole and system (athlete + pole) energy during the pole vault and movement sequence approximately aligned with key instants of energy transformation. E: energy, KE: kinetic energy, PE: potential energy.
Roll the pole
Besides managing energy production and losses during the jump, the athlete faces another vital challenge. To roll the pole forwards and over the end that’s planted in the box after take-off, so that when it starts to unbend, it launches them upwards and forwards towards the mat (not backwards towards the runway). It might seem at first glance that the athlete is just hanging off the end of the pole as they jump and swing to get upside down. However, they are in fact actively pressing the pole away from them to roll it towards the mat, simultaneously swinging their body to stay behind the line of the pole (shown in the image below). The execution of the swing – the timing, body positioning, and muscular work – is the key to adding energy to the system while the pole is bending.
The production of kinetic energy during the run up, rolling the pole after take-off and proficient execution of the swing combine to have a crucial effect on pole vaulting performance, because they determine the system energy gain and body position when the pole starts to unbend. The position of the athlete and pole at the instant of take-off and the actions immediately thereafter are therefore critical to set up the rest of the vault, and a large proportion of an athlete’s technical training is spent on this phase.
Choose your flex
A unique element of pole vaulting is the ability of the athlete to select the type of pole they use and manipulate where they position their grip. Poles range in length (most elite male vaulters are using 5.00 - 5.20 m poles, and females 4.30 - 4.60 m) and stiffness (represented by a number called the flex index; the lower the number, the stiffer the pole). The vaulter’s grip is measured to the position of the top hand. Lowering the grip on the pole makes it easier for the athlete to rotate the pole and effectively increases the pole stiffness. A stiffer pole is harder to bend but allows greater energy return, which is advantageous if the athlete is capable of bending it (requiring higher approach velocity and greater strength) while maintaining good technique. Therefore, as bar heights progress during competition, athletes make decisions about adjusting their grip and/or moving “up pole” (selecting a longer pole and/or one with a lower flex index) to achieve greater vault heights.
Varied technical approaches
From a mechanical energy perspective, the science of pole vault performance is quite black-and-white. However, because all athletes have different individual characteristics and there are so many interacting variables that contribute to the vault outcome, there is no single technical model that will optimise performance for all athletes.
This was the topic of a recent research study that analysed the best competition vault of 99 male athletes that cleared between 5.00 m and 6.22 m (52 of them jumped over 5.40 m). Two parameters that describe variations in the period of time from take-off to MPB were used to group athletes into one of four clusters. The first parameter was the position of the top hand relative to the foot on the ground at take-off, where athletes fell on a spectrum of being more “negative under” (hand further behind the foot) or closer to a neutral alignment (hand directly above or just in front of the foot). The second parameter was the direction that the top hand travelled from take-off to the point of MPB (defined as the angle between a line from the hand location at these two instants and the horizontal). The four clusters were therefore “negative and high”, “negative and low”, “neutral and high” and “neutral and low”.
Figure 2. Scatter plot of each athlete's under position and direction of the top hand, showing the four clusters of technical approaches. See a short video clip at the bottom of this post for some additional visuals on a selection of jumps and tracking of the hand during the vault.
There were no significant differences between the athletes in the four clusters for their height, body mass, grip height, take-off speed, or vault performance (the height of the bar they cleared). However, each approach was associated with different athlete-pole interactions that induced variations in pole bending at take-off and MPB.
At take-off, the two “negative under” clusters had already initiated pole bending, whereas the “neutral” groups had almost fully straight poles. It seems the more negative under take-off position utilises the contact period to initiate the pole bend, which can be an effective way to transfer energy into the pole but might carry greater injury risk because of the hyperextended spine and shoulder position and high forces occurring when doing this. Although the average pole flex index was similar between the two negative under clusters, the “negative and high” group achieved less bend by MPB, suggesting that they may rely more on maintaining athlete kinetic energy rather than transferring energy to the pole, compared to the “negative and low” group that experienced greater bend. Athletes in the “neutral and high” cluster utilised stiffer poles than any of the other three groups, and experienced less bend by MPB than the “neutral and low” group. It appears that a similar outcome can therefore be achieved from a neutral take-off with a stiff pole + less bend + higher trajectory, or a softer pole + more bend + flatter trajectory to MPB. A possible concern with the low trajectory, though, is that it might be more difficult to execute the next phase of the vault because the athlete has already travelled further horizontally – so there’s less margin for error as they invert and clear the bar.
The study concluded that equivalent pole vault performance can be achieved using each of these different technical approaches, but that they each have different implications for the athlete-pole interaction and physical and technical demands of the event. Coaches and performance support staff working with pole vaulters could potentially assess these two parameters to categorise their athletes and use it as a guide to improve the specificity of training. The findings also raise questions about when during the developmental pathway these preferred technical approaches form, and the constraints that influence their emergence. This knowledge might assist coaches of novice athletes to enhance the learning process.
Pole vaulting is in the spotlight of world sport at the moment, with Mondo Duplantis literally raising the bar to new heights at just about every major competition, and fierce competition in the women’s event where we just might see more athletes break that 5-metre barrier before long. Keep an eye on the field and see if you can spot any differences in technical approaches!
Thanks to Johan Cassirame for providing some of the visuals used in this post, including the above video.
References:
Cassirame J, et al. Clustering technical approaches of elite and world-class pole vaulters based on 10 years of measurement during competitions. J Sport Sci. 2024; 42(11):971-80. https://doi.org/10.1080/02640414.2024.2372940
Frère J, et al. Mechanics of pole vaulting: a review. Sports Biomech. 2010; 9(2):123-38. https://doi.org/10.1080/14763141.2010.492430
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