Physics behind inflatable ball collision

[iDimension]

Hello all, I've seen the videos many times before, where two people run at each other with giant inflatable balls and one of them will go flying while the other will hold their ground. I always wondered what is responsible for one person being propelled into the air while the other person feels almost no effect.

Sometimes it's the person running the fastest, or the slowest, or the smallest, or the heaviest... It does seem rather random. So is there a way to run at someone and guarantee that you are not the one who gets sent across the room?

I imagine that if it was me I would run at them and then just as we are about to collide, place my feet in a stable position and try to maintain a lower centre of gravity while slowly leaning into the ball.

 

[Bystander]

lower centre of gravity

I think you've put your finger on the secret.