What is more difficult: a golf swing or running?
It seems to be a pretty common opinion that running is a natural ability, you don’t need to learn it, and, for the most part, you are born with whatever speed you have. However, if we think about what is happening while running, it may even be more complicated and less intuitive than a golf swing.
I don’t golf, but I know that swinging a club takes a lot of practice. The first time someone swings a club, they might think to use their arms as the primary movers of the club. After learning and practicing, they discover that the hip initiates the entire movement and they have an epiphany when they feel the ease with which the swing occurs. The relative simplicity of the golf swing is that you only have to change direction once: wind it back and swing.
The challenge in running is to move one foot forward fast enough to have time for it to move the opposite direction and accelerate to a speed at least as fast as the relative speed of the ground. Then repeat that sequence over and over. The last part is what people seem to have trouble with - accelerating the foot backwards before it contacts the ground. This seems to be opposite of our intuition: to move forward, we must reach forward. It appears that more often, people are not able to accelerate the foot backward and the foot lands as it is moving forward. This is called braking - it slows you down and uses more energy.
Another added challenge in running efficiently is that you can do it wrong and not know it. If it is all you have ever done, you have nothing to compare it to. At least with a golf swing, you have some feedback from the flight of the ball.
To really asses the complexity of running, we have to add all of the other movements. If you consider the movements of the legs, arms, and core that are necessary to facilitate accelerating the foot backward, then you have the complex, and potentially beautiful, poetry called running.