The Steps to Understanding Exercise
Understanding exercise gets a reputation for being complicated. Usually that isn't down to a gap in scientific knowledge. It's not knowing where to begin.
We overcomplicate it. We try to be clever, or we get pulled in by whatever a fitfluencer posted this week. The process is simpler than that.
It starts with one question: which job are you doing?
Designing an exercise to target a specific muscle, or
Analyzing an exercise someone else has "designed"* to see what it challenges.
(*”Designed” being generous.)
Get the scenario clear and the thinking falls into place.
Designing an exercise for a specific muscle
You're here when a client wants to improve a particular muscle's size or function, or when a physio has flagged an "underactive" or weak muscle behind someone's pain.
This is the path that asks more of your anatomy. You need to know where each end of the target muscle attaches, and which joint function rotates a joint axis in the same plane as that muscle's fibers, so the muscle lengthens and shortens as fully as possible.
From there:
Identify the muscle (or muscles) you want to stimulate.
Picture the joint function that happens when that muscle shortens, then reverse it. You've just defined a concentric and an eccentric.
Build a setup that points resistance straight along that path of motion.
Hold that joint function and that line of resistance in place, and stop other joint functions creeping in (isometric control, or physical support).
Do that and the hard part is done. Now it gets personal:
Check the range of positions the individual actually has in that joint function, and set the exercise up to fit it.
Decide how much of the range you want to be a challenge, and shape the resistance through the range to match.
You've now got a setup aligned to one person and one goal.
Analyzing an exercise you've seen online
Someone posts a movement with a made-up name and a big claim about what it builds.
How do we challenge their ideas that performing a specific joint function (or combination of them) will achieve a certain muscular stimulus?
Start with the axis. Imagine driving a rod through the joint at the one angle that wouldn't interfere with the movement happening. That line is the axis.
Then the plane. Picture the working limb wiping a sheet of glass as it moves. That pane is the plane of motion, and the axis sits perpendicular to it.
With the axis and plane identified, check the resistance against two things:
Is it aligned with the plane of motion?
Is it pointing in the correct direction relative to the axis?
It sounds obvious .. but you'd be surprised how often people get the joint function right and then the application of rresistance is back to front.
With the resistance aligned with the plane and pointing the right way, you can read the working musculature, assuming that:
Every muscle on the opposite side of the axis to the resistance is working. The brain reaches first for the muscles best aligned with the plane of motion, and as you push toward failure it recruits everything that can contribute.
The muscle doing the most work, seeing the most stimulus and the biggest change in length, is the one most aligned with that plane.
The claim either survives that read or it doesn't.
None of this needs a lab. It needs a framework of analysis, applied the same way every time. We teach it joint by joint on RTS Level 1.