In the late 1980s, David Belle was watching his father Raymond lay the foundations of what would become “Parkour,” or “free-running.” Raymond, a skilled athlete, got the brick and mortar he needed to do so from a French naval officer named Georges Hébert, and Hébert got his inspiration from the “flexible, nimble, skillful” native peoples of Africa. He put together a training regiment based on these movements for military officers and imparted this wisdom to Raymond Belle, who in turn taught his son David. Soon, David and a training group came up with “Parkour,” from the French parcours du combatant, or an obstacle course used to train soldiers of the French military.
In 1998 The Legend of Zelda: Ocarina of Time made the biophysics of Parkour a game mechanic.
“When you jump off a high cliff, if you hold forward, you will roll on the ground when you land and won’t get hurt from the fall. I can’t guarantee it will work, though, if the cliff is really, really high, heh heh!”
That’s the advice you get from a Deku scrub after deflecting a giant nut back into its face. And it turns out to be good advice. Fall off an infuriatingly small ledge in the Fire Temple? Just make sure you hold the N64 controller joystick forward and you won’t lose any hearts. But even rolling won’t save you from the highest of heights. Ocarina of Time understood the biophysics of Parkour before Parkour was cool.
No one is suggesting that the minds behind one of the most critically acclimated games of all time consulted doctors and scientists when devising a way to save Link from fall damage. It was probably simpler than that. Perhaps there were a cross-pollination of ideas. Maybe a developer knew of a technique from the burgeoning extreme sport of Parkour. Maybe it was just a coincidence, or nothing. Still, rolling after a fall made intuitive sense. It makes scientific sense too.
They say it’s not the fall that kills you; it’s the rapid change in momentum. Okay, nobody says that, but it’s still true. Momentum is a product of mass and velocity. And if you change momentum over time, it produces a force (F=m*((vf-vi)/(tf-ti)) if you want to get technical about it). That is to say, the quicker something moving comes to a stop, the more force that is applied to it. It is the reason why you can catch an egg safely on a sheet but not on concrete – the egg has more time to stop.
Extend this principle to a Parkour roll. There is nothing special about the roll itself — it’s simply a motion where you can bend your legs almost all the way to absorb an impact without smashing your knees or stopping dead. The longer your body has stop, the less force on you.
And what a force that could be. Let’s do a quick calculation. Say I throw my 70 kilograms off a 3-meter (10-foot) ledge. Ignoring air resistance (like a good introductory physics student), by the time my feet touch the ground I will be traveling at around 8 meters per second (18 miles per hour). When I do hit the ground, I lock my knees. All of my momentum comes to rest in maybe a hundredth of a second. I experience 50,000 Newtons (12,000 pounds-force) of force.
Here’s where the Parkour technique makes sense. If I can extend my impact with a half-a-second roll, absorbing the force over time with my legs, the force on me is reduced to only 1,100 Newtons (242 pounds-force), or one-fiftieth what it was.
Like a lot of advice you’ll get in a gym, however, the Parkour roll could be all talk and no physiology. Who’s to say that rolling like Link really works? Well, according the conclusion of a study published in the Journal of Sports Science & Medicine, “The landing techniques encouraged by local Parkour instructors such as the precision and roll appear to be more appropriate for Parkour practitioners to perform than a traditional landing technique due to the lower landing forces and loading rates experienced.”
It works in Ocarina, physics, Parkour practice, and the medical literature. But there is a limit.
Even if you roll, there is a maximum height you can fall from. Imagine a chart showing how much you can increase your time of impact versus the velocity you hit the ground with. Beyond a certain height, you will be going too fast upon impact for the extended time to mitigate the force on your feet.
For Parkour athletes, that might be any height above 15 feet, though some can roll safely out of falls much higher. Medically, the height that is fatal for half of fall victims is around 50 feet or four stories. That’s potential survival for a fall much higher than 15 feet, but keep in mind that no one exactly walks away from a 50-foot fall to collect more Pieces of Heart.
If you go by Google search trends, Parkour itself didn’t really enter the pubic consciousness until the mid 2000s. That’s two decades after David Belle learned the art of movement from his father, and almost a decade after Ocarina of Time was released. Again, it’s probably just a fluke that Link and his animators made falling damage dependent on rolling after a fall, but maybe the next time a talking bush has some biophysics advice for you…Hey, you should listen!
Kyle Hill is the Science Editor at Nerdist Industries. Follow on Twitter @Sci_Phile.
IMAGE: Sacred Flames
Hat tip to manga artist Sara E. Mayhew for the article idea.