When we look at running technique, it's often easy to focus too much on specific actions that are incidental to other more fundamental actions. Then when we try to imitate those incidental actions, all hell breaks loose.
For example, if we move our body forward, our feet will move quickly to catch up. This fast cadence is observed by a student of running, and that student might jump to the conclusion that she/he needs to move his/her feet quickly to match the technique of that runner. But, from that runner's point of view, she/he simply tried to move forward, and her/his feet moved quickly in response to get back under their body.
Another example is "leaping". Running, by definition, means that both feet are off the ground at some point in each step. So the observer may conclude that "leaping" or "jumping" is fundamental to running. It almost makes sense, if the feet both need to be off the ground to be running, then it must be necessary to launch the body up into the air, in a jumping manner.
However, it isn't necessary, and in fact, it can be counter-productive to TRY to jump with each step. After all, the fundamental goal of running is to move the body forward. "Leaping" or "Jumping" is up and down movement, which may be incidental to a fast cadence while the body is moving forward quickly... But fast cadence, itself, as I mentioned above, is incidental to moving the body forward.
Will the body move up and down while running? Probably. But if you TRY to launch your body into the air, we lose several things;
1. Forward momentum - we have just diverted our bodies from moving forward (the direction we're trying to go).
2. Cadence - The harder we push our body up into the air, the longer we need to wait for it to come crashing down again - that excess time necessarily slows down our cadence.
3. Gentleness - The harder we push our body up into the air, the harder we come crashing down again.
Anyway, it's a lot easier to use our massive (relative to our feet) body to lift our small (relative to our body) feet, than it is to launch our massive (relatively speaking) body into the air using our small (relative to our body) feet.
So, essentially, running (and walking) is about moving the body forward. Most every other action, it could be argued (and I am), is incidental to that.
The following video is old, but it emphasizes the same point:
Running Technique: Fundamental and Incidental Actions
Blog entry posted by Barefoot Ken Bob, Jan 12, 2015.
About the Author
Webmaster and founder of the Original Running Barefoot website (1997-present) - BarefootRunning.com, President Los Angeles Chapter of The Barefoot Runners Society (2010-present), Co-author; Barefoot Running Step by Step (2011), Barefoot Running Guru (1997-present), completed more than 400 races barefoot (as of 2012), including 79 marathons (26.2 miles each), and one ultra-marathon (50 kilometers+)