Thoughts About "Right" and "Wrong" Technique (Part 2 - "Full" Range of Motion)

In a previous blog post, I examined some issues with the notion of what might be considered "correct" technique for exercise execution.  My main focus for that post was range of motion -- or more accurately, the guidelines that we sometimes give about "neutral" joint position and how that might differ from one person, joint, context, etc. to the next.

While the topic of neutral joint position could further be explored until we're blue in the face, I'll move on a bit to another subject that is often brought up in technique instructions that logically follows from that one: the idea of "full range."

The phrase "full range of motion" gets tossed around a lot and is often used in the context of maximizing hypertrophy (though it sometimes gets mentioned when we are talking about injury prevention as well).  Indeed, there is research suggesting that all (or at least most) other things being equal, excursion through a greater range of motion during an exercise may provide a greater mechanical stimulus to the working muscle, as more mechanical work is being done.  If you're moving at a given angular velocity, then moving through a greater range will result in a longer repetition and thus more "time under tension" for that rep (my issues with this phrase can be saved for another time).

Tension generation is a product of (among other things) a muscle's length, itself related to the length of sarcomeres within that muscle (OpenStax Anatomy & Physiology, Fig. 10.14 from Section 10.4)

It should be mentioned, however, that much of the available research relies on assumptions about how much internal tension a given muscle is generating at various points throughout the range -- particularly when we're looking at free weight compound movements such as a barbell squat.  Thus, we don't know how constant the linear tension generated by a given muscle actually is.  Taking the gluteus maximus as an example, you have a fan-shaped array of muscle fibers that are all shortening (or being lengthened) at varying rates and which may vary their contribution based on the external torque being applied to the hip and contribution of other hip extensors (read: three of the four hamstrings) and co-contraction of other muscles crossing the hip that may contribute to hip extensor demands.

What does this ultimately mean?  Well... I don't know.  At least, I can't give a single guarantee of an answer.  It suggests that while there may be a tendency for greater hypertrophic stimulus when we go through longer ranges, it may not always be the case, as in real-world scenarios involving loads that aren't controlled as tightly as they are in the lab, we can't know for certain what any given muscle is actually doing (in fact, even in the lab we have to make a lot of assumptions about that).  So just keep it in mind.

Now let's assume that we have decided on going "full range" anyway.  Which joint(s) are we talking about?

My deep squat will *never* look this clean.  I'm gonna blame my structure.

If we take the squat -- an exercise that I keep picking on, because why not -- we have to consider that your depth can be limited by one or more of the involved joints.  Maybe you get "stuck" with hip flexion as your limiting factor (ignoring rounding of the back and associated "neutral spine" stuff which relates to the previous blog in this series).  What if your knees still have a lot more flexion available?  Maybe you can shift your position somewhat to require a little less hip flexion and a little more knee flexion, though this can also shift the muscular demands (remember the earlier points about not knowing how much actual *tension* is being required of a given muscle?)

And hey, what about the ankle?  Might there be a situation in which we want to maximize range of motion at the ankle to get those sick calf gains?  (Don't laugh -- there may be a time and a place to do exactly that!)  What if the ankle is the limiting factor no matter how you shift things, meaning that you're not *really* accessing the full available range at the hip and the knee.

That brings me to my next point.  This whole time, I've been writing about the full range of a joint without really defining that.  There can sometimes be substantial differences between active range of motion (range through which you can voluntarily move a joint without some external force/torque assisting) and passive range of motion (range that is available when external forces push the joint to the point where passive structures and/or involuntary muscle contraction limits further movement).  Try actively flexing your hips, flexing your knees, and dorsiflexing your ankles, each separately.  Now see how much range you can get out of each of those as you settle into a body weight squat.  You may notice that there is a difference at one or more joints.

This individual may be tapping out their hip flexion range while still having some knee flexion and/or dorsiflexion available.  Thus, there may be near-full excursion of the glute max but not of the quads, etc.  This is something we should consider as we make decisions about which muscles are undergoing significant length changes while creating tension and how we might modify and/or combine exercises to stimulate the desired tissues.

The truth of the matter is that most exercises that we do -- in the ways that we normally do them, at least -- do not allow for a substantial amount of loading to be applied to the desired muscles through their available range of motion (active *or* passive).  This is especially true when we are talking about exercises wherein the resistance is primarily derived from a source whose vector doesn't change much (in the case of a band/cable that probably isn't changing its orientation relative to our body much throughout the range) or at all (such as with a free weight whose resistance vector in a controlled, constant-velocity rep will be pointing down the entire time, because gravity).  If you *really* want to get closer to applying resistance to a muscle or group of muscles through a larger range of available lengths (which is really what we're talking about when we're talking about "range"), you'll probably want to explore machine-based options.  See this post which talks about some considerations for bodyweight exercises for a few relevant points about machines and the opportunities they provide.

If all of that seemed like a big, confusing mess... don't worry.  That's to be expected.  There are a lot of factors to consider when trying to apply force to the body in a strategic way, and that sometimes means that we have to spend a while unpacking even things that seem pretty simple so that we can eventually put all of those pieces back together with greater understanding.  More posts will come which examine factors relevant to range of motion, tension created by muscles, hypertrophic stimulus, joint torque, etc.  

ALSO -- If you enjoyed this topic and want to explore things like it further, be sure to check out our membership options HERE.  We have weekly Q&A roundups, short special topic videos, full-length course lectures, and even a discussion forum where you can talk with other members about this stuff (or toss your questions directly at Alex and me!)

 - G

Source:

1) OpenStax, Anatomy & Physiology . OpenStax CNX. 2017
https://openstax.org/details/books/anatomy and physiology