One of the main things onlookers say when they see people training parkour is, “Do a backflip!” As mentioned in my post 5 Things Not to Say to Someone Who Practices Parkour, asking if trainers can do a backflip is a really weird question that no one wants to be asked. Let me spare you the awkwardness and answer on behalf of (almost) all parkour trainers: Yes, they can do a backflip.
But this got me thinking about why backflips are so fascinating. I think there are several reasons, and I wanted to delve into each in turn. (Warning: physics stuff to come)
First of all, to start rotation, arms have to be swung with enough force to give initial angular momentum. Unlike normal momentum, which is the product of mass and velocity, angular momentum is the result of rotational mass and angular velocity. This rotational mass, i.e. the moment of inertia, is dependent on both the mass of an object, and the distribution of this mass. In short, generating enough force to fling yourself into the air is a feat in itself, one that I am scared to try even with supervision for fear of over-doing it and falling.
Once in the air, legs must be pulled in close to the chest to decrease rotational mass and increase angular velocity.
Finally, landing feet-first and maintaining stance despite momentum is the final hurdle of performing a backflip.
Overall, a backflip requires an appropriate power-to-weight ratio and rapid responsiveness which, for many years, was possible only for humans. However, in November 2017, a robot named Atlas, created by Boston Dynamics, became able to achieve this.
This just goes to show that, while a backflip serves no useful purpose, we as humans are fascinated by them as a marvel of physical prowess that now we’re building robots that can do them too.
While some argue that backflips are not a part of parkour, i.e. efficient movement from point A to point B, backflips are often featured in lines of the more creative movement discipline of freerunning.
Overall, parkour and freerunning are amazing physical disciplines that require equal parts skill and determination, both of which I admire in trainers, and are made up of more than just backflips. Keep that in mind the next time you see people training, and don’t be that person who shouts out, “Do a backflip!”
Until next time, remember, “the way of the parkour is to continue, not to stay here” (Sebastien Foucan, n.d.).