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Traceurs, or parkour athletes, seem superhuman in their ability to scale up walls and drop down from rooftops without injury. But it turns out that there’s a fair amount of biomechanics at play behind these powers.

Hosted by: Hank Green

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Sources:
https://jeb.biologists.org/content/222/1/jeb190983
https://jeb.biologists.org/content/jexbio/222/1/jeb190983.full.pdf
https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1056&context=psychpubs
https://www.tandfonline.com/doi/abs/10.1080/02701367.2013.762300
https://www.tandfonline.com/doi/full/10.1080/10255842.2020.1714932
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3761764/
https://hal.laas.fr/hal-02042616/file/Maldonado-et-al-2018.pdf
https://content.sciendo.com/view/journals/hukin/72/1/article-p15.xml
https://www.tandfonline.com/doi/full/10.1080/10255842.2017.1382892?utm_source=TrendMD&utm_medium=cpc&utm_campaign=Computer_Methods_in_Biomechanics_and_Biomedical_Engineering_TrendMD_1&origin=a70d7697d3ec186bcd03b87562bebf24
https://www.tandfonline.com/doi/pdf/10.1080/10255842.2017.1382892?needAccess=true

Special thanks to Ronnie Shalvis for the parkour footage!
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https://www.istockphoto.com/photo/man-practicing-parkour-gm887533250-246313754
https://www.istockphoto.com/photo/group-of-friends-playing-basketball-gm611183278-105120405
https://www.istockphoto.com/photo/serious-female-soldier-leaving-home-gm1210807296-350915326
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[♪ INTRO].

If you’ve never seen parkour before, it is a sport that looks… kind of impossible. Traceurs, or people who do parkour, run up walls, they jump between buildings, and somehow they do not explode on impact after jumping off a second-story roof.

As you might expect, there’s a lot of biomechanics involved, and by analyzing parkour skills scientifically, researchers have gotten a pretty good idea of what it takes to parkour like a pro. One of the most common parkour stunts is wall climbing. It involves running toward a wall and then planting one foot on it — launching yourself up high enough to grab the top.

It looks pleasantly superhuman, and one thing in particular caught scientists’ attention: that in-between step transitioning from flat ground to the vertical wall. It is not easy to turn all that horizontal motion into vertical motion, but somehow traceurs pull it off gracefully. So in a 2019 study published in the Journal of Experimental Biology, researchers set out to see out how these athletes do it.

They built a DIY runway and wall and filmed a handful of experienced traceurs in action. Their setup had two force sensors: one on the runway to measure the force of the final horizontal step, and one on the wall to measure the force of the vertical step. This let the researchers measure how forcefully the traceurs stepped off the ground and how hard they landed on the wall.

Now, you might think that to make it up the wall, you’d need to be able to jump super high, but the experiment actually showed that technique was more important than raw strength. Most of the time, in a successful wall-climb, the foot on the wall landed below the traceur’s hip height. To figure out what was so special about that placement, the researchers took the data from the two sensors, along with the footage they’d collected, and they built a simulation.

The simulation showed that, by placing their foot in just the right spot, traceurs were able to sort of glance off the wall and conserve their momentum rather than losing a bunch of it to the wall. But that only worked if they were moving at the right speed. If the traceur ran too fast at the wall, their leg had to work extra hard to keep them from colliding with it, kind of like a shock absorber.

On the other hand, if they ran too slowly, the other leg would have to spend a lot of energy to thrust upward, so that wasn’t ideal either. They concluded that there was a sweet spot — an intermediate approach speed that was the most energy-efficient way to get up the wall. And the ideal approach speed they calculated was very close to what the athletes were already doing!

Another parkour skill is the kong vault, which involves scrambling over obstacles like an extreme version of leapfrog. And in spite of the name, it’s actually pretty different from other vaults, like the kind people do in gymnastics. The main difference is that a gymnast wants to vault as high as possible, while in parkour, the goal is to stay low and maintain horizontal speed.

As a result, the two moves use the body completely differently. In 2020, biomechanics researchers published the very first analysis of exactly what happens during this vault and how it compares to the more familiar gymnastics stunt. Similar to the wall-climbing study, they put force sensors on and around a.

DIY obstacle and brought in traceurs to vault over them. From the data they collected, they were able to build a model of a normal kong vault that included the forces and torques on individual joints at different points in the stunt. And they found that, as extreme as it looks, the kong vault is actually pretty gentle on the body.

Since the move stays so close to the ground, traceurs don’t need to spend much effort getting up in the air. Like, in one study, a gymnast kicked off the ground with a force more than seven times their body weight to get into a vault. In comparison, traceurs exerted a force just slightly higher than their body weight to do a kong vault — and they also had a much softer landing.

Which brings us to our last skill. As parkour has gotten popular, researchers have analyzed various parkour skills, but one question has attracted more attention than any other:. How do traceurs land so gracefully?

Often, they’re hitting the ground from very high up, but they never seem to have a hard landing. Sometimes when they hit the ground they’ll tuck their bodies and roll over one shoulder. Other times they stick the landing, but drop into a deep squat.

And based on the fact that traceurs don’t shatter their joints upon landing, it seems pretty clear that these techniques minimize the force these athletes feel on impact. Sure enough, a 2013 study backed that up by having experienced traceurs land on a force plate and comparing the impact of various landings. By bending into a deep squat or rolling out of a stunt, they were able to absorb that force over a greater period of time, instead of taking the hit all at once.

Now, this research doesn’t just apply to jumping off buildings. Scientists hope that strategies from parkour can help athletes, soldiers, and even weekend warriors stay active and avoid injury in their everyday lives. Thanks for watching this episode of SciShow!

And a special thank you to our patrons, who make up part of the amazing community that keeps SciShow going! We love making these videos and we couldn’t do it without you. So if you like what we do and you’d like to become a patron, you can find out more at patreon.com/SciShow. [♪ OUTRO].