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## Glute deactivation/amnesia. Devil's advocate question.

The question is at the bottom of this post.

Force and motion are two sides of the same coin. If a single object undergoes a change in motion, there is only one net force (with a specific direction and magnitude) that could have produced that change.

In the context of human movement, where we are dealing with a system of bones that rotate about joints, there is only one set of net torques that could have conspired to produce a particular pattern of movement. Note that even if a bone rotates with uniform circular motion (i.e. net torque of 0), gravity is often part of the equation, and a force must be generated by muscles to counteract the torque due to gravity.

If you tweak the net torques, the shape of the movement, across time and space, will change.

Accordingly, if a particular movement pattern requires a certain amount of force to be generated by any particular set of muscle fibers, then it is simply impossible for that movement pattern to occur without the contribution of those muscle fibers.

No reasonable and sane person who understood these principles could object to this. And, with a bit of common sense, and physical demonstration, they may be convinced that the best way to shape a movement pattern into a desired form is to practice the movement pattern itself, with the help of verbal, tactile, and visual cues, rather than to do some muscle activation corrective exercises.

But, they might say, what if you could achieve the same set of net torques with multiple possible patterns of muscular involvement? For example, if you had two separate muscles whose respective attachment points were offset by a small amount (e.g. muscle A's attachment points are a couple inches proximal of muscle B's attachment points) such that the direction of force is equivalent for each muscle. Then, there are an infinite combination of firing patterns that could produce the same net torque at the joint.

Or, more realistically, what if you had two separate muscles which, while having different angles of application, could still provide the same net torques. For example, tension in the hamstrings between the ischial tuberosity and an anchored tibia produces a torque in the acetabulofemoral joint about a different axis than does tension in the gluteus maximus between the ilium and the femur (the glutes pull more "sideways" compared to the hamstrings). Yet, if the joint is "stable", either due to constraint forces provided by the interaction of the head of the femur within its socket, or due to the contribution of stabilizing muscle groups (e.g. internal hip rotators), the net torque at the acetabulofemoral joint could be identical, across multiple combinations of glute and hamstring contributions.

To this, one might respond as follows:

If the muscle is lengthened during the eccentric phase of the movement, then it will contract during the concentric phase as it shortens. So, during the eccentric phase of the squat, if the glutes lengthen (and they cannot help but lengthen), then they will contribute accordingly during the concentric phase.

At this point there is one remaining objection. Well, they might say, just because a muscle shortens doesn't mean it was actually firing. If I flex my elbow joint, and then have someone extend my elbow, the triceps have gone from a lengthened state to a shortened state without tension being generated. Similarly, the glutes may shorten without producing their own tension - they may be "spotted" by the hamstrings on the way up in the squat.

My answer to this would be: I don't think that's how the neuromuscular system behaves. Movement is arguably one of the most fundamental tasks that mammals have to carry out. As such, our phylogeny and ontogeny have ensured us that we will use the appropriate muscle groups when solving a problem such as hip extension. In the absence of severe pathology (e.g. central or peripheral nervous system, or muscle lesion), the glutes will fucking contract when they're supposed to. In fact, it would be an extremely challenging thing to do, if not downright impossible, to contract the hips without "proper" glute activation.

Rip, my question to you is whether there is a better answer to this objection than the appeal to evolutionary common sense.

2. Don't have time to read this right now. Discuss amongst yourselves.

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I am a neuromuscular subspecialist. I think I know what you're asking....

Originally Posted by spacediver

Accordingly, if a particular movement pattern requires a certain amount of force to be generated by any particular set of muscle fibers, then it is simply impossible for that movement pattern to occur without the contribution of those muscle fibers.
The above is not true and I think self-evidently so. I see patients with neuropathies or myopathies that may cause infinite unique patterns of focal or non-focal muscle weakness or atrophy and many are able to reproduce the same normal movement patterns as before, albeit with less force or efficiency. There is redundancy in the neuromuscular system. For example, a patient with a mild myopathy (which causes non-uniform muscle weakness) might be able to squat with perfect range of motion with different relative contributions from muscle groups or motor units within those muscles. Such a person will have less neuromuscular reserve and thus less strength, however.

Originally Posted by spacediver
But, they might say, what if you could achieve the same set of net torques with multiple possible patterns of muscular involvement? For example, if you had two separate muscles whose respective attachment points were offset by a small amount (e.g. muscle A's attachment points are a couple inches proximal of muscle B's attachment points) such that the direction of force is equivalent for each muscle. Then, there are an infinite combination of firing patterns that could produce the same net torque at the joint.
The above is thus true, even in a healthy individual. The nervous system evolved as a sensory processing organ, yes, but in humans especially, the majority of it is devoted to action selection and movement. It has become evident to AI/robotics researchers that joint movements are very complex and the computations that human cerebellum and other areas perform were grossly underestimated. As you learn a movement through repetition, the central pattern generators in the central nervous system are honed and converge upon the most efficient use of your neuromuscular assets for that movement. During the learning process, the same net force will be produced with a variety of neuromuscular outputs.

I think this is maybe what you're getting at--that as movement efficiency approaches 100%, the set of possible neuromuscular outputs to produce that movement approaches 1. That's where getting coaching and learning the lifts properly comes in.

By the way, I agree with the point Rip has made all along that training on just the basic lifts provides a set of inherently valuable movement patterns upon which a large number of useful movement patterns can be built.

4. Originally Posted by dfclark68
I am a neuromuscular subspecialist. I think I know what you're asking....
What is a neuromuscular subspecialist?

The above is not true and I think self-evidently so. I see patients with neuropathies or myopathies that may cause infinite unique patterns of focal or non-focal muscle weakness or atrophy and many are able to reproduce the same normal movement patterns as before, albeit with less force or efficiency.
Or perhaps more force and efficiency, albeit with either greater or lesser amounts or increments of neuromuscular subspecialization.

There is redundancy in the neuromuscular system.
But only in the redundancy-dependent subsystems subsequent to the frontal cortex/brain stem/other processor subcategories.

For example, a patient with a mild myopathy (which causes non-uniform muscle weakness) might be able to squat with perfect range of motion with different relative contributions from muscle groups or motor units within those muscles. Such a person will have less neuromuscular reserve and thus less strength, however.
However, we're seeing amelioration of these syndromes subsequent to the rather vigorous "myopathic fleshing" that sometimes quite frequently occurs in the normal course of "muscular revetment construction" during and immediately subsequent to normally-reinforced squat movement pattern reinforcement.

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As Rip has pointed out with excellent and well below average clarity, neuro, neurotic, and/or neuromuscular cessations preambulate despite intrusions from de-myelinated nerve cells. This compensatory intrusion will dominate within the pattern as loading variables wave vertically across the lateral force production milieu.

Commingling of disease states and training outcomes will, apparently, continue to dominate the therapeutic specificities, making Rippetonic clarity around the subject elusive.

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Originally Posted by dfclark68
The above is not true and I think self-evidently so. I see patients with neuropathies or myopathies that may cause infinite unique patterns of focal or non-focal muscle weakness or atrophy and many are able to reproduce the same normal movement patterns as before, albeit with less force or efficiency. There is redundancy in the neuromuscular system. For example, a patient with a mild myopathy (which causes non-uniform muscle weakness) might be able to squat with perfect range of motion with different relative contributions from muscle groups or motor units within those muscles. Such a person will have less neuromuscular reserve and thus less strength, however.
The bolded quote in my original post is a tautology, so it has to be true. The point you are making is that the premise:

if a particular movement pattern requires a certain amount of force to be generated by any particular set of muscle fibers...

is not true. If it were true, then this would reflect a case where there is no redundancy.

Originally Posted by dfclark68
The above is thus true, even in a healthy individual. The nervous system evolved as a sensory processing organ, yes, but in humans especially, the majority of it is devoted to action selection and movement. It has become evident to AI/robotics researchers that joint movements are very complex and the computations that human cerebellum and other areas perform were grossly underestimated. As you learn a movement through repetition, the central pattern generators in the central nervous system are honed and converge upon the most efficient use of your neuromuscular assets for that movement. During the learning process, the same net force will be produced with a variety of neuromuscular outputs.
This makes sense. Control theory is probably the appropriate discipline that can explore the mapping between neural events in the CNS and the resultant torques at a particular joint.

Originally Posted by dfclark68
I think this is maybe what you're getting at--that as movement efficiency approaches 100%, the set of possible neuromuscular outputs to produce that movement approaches 1.
No, my question is this:

Suppose we accept the fact of redundancy (as in the example I give of the glutes and hamstrings in hip extension). A muscle activation proponent may come along and say:

"See? Because of this redundancy, there is no guarantee that just because a movement looks correct from the "outside", that the proper muscles are being activated. This poor patient, who suffers severe gluteal amnesia, may look like he's squatting correctly, but in fact, the hamstrings are doing a larger share of work than they should be, and the glutes are just going along for the ride without generating the amount of tension they should be. We must spend a few weeks teaching this patient how to activate their glutes, doing glute activation work"

A response to this is that the glutes must be doing work, because they are being stretched during the eccentric phase of the squat, and they will therefore actively contract during the concentric phase. This is the same argument Rip makes in his book when discussing the role of the adductors in the squat (top right paragraph, page 48 in SSBBT 3rd edition).

So now that you've responded this way to the muscle activation specialist, suppose he then replies:

Well just because a muscle lengthens doesn't mean it generates its own tension when it shortens (and they give the example of passive extension of the elbow joint without any tension generated in the triceps). My question is:

"How does one best respond to this final objection?".

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Originally Posted by Mark Rippetoe
However, we're seeing amelioration of these syndromes subsequent to the rather vigorous "myopathic fleshing" that sometimes quite frequently occurs in the normal course of "muscular revetment construction" during and immediately subsequent to normally-reinforced squat movement pattern reinforcement.
The Been is strong with you, sir.

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Originally Posted by Mark Rippetoe
What is a neuromuscular subspecialist?
I'm a neurologist (MD) who specializes in neuromuscular disorders. I loved Bill Been's recent presentation and am laughing at myself as I go back through my comments.

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Originally Posted by spacediver
The bolded quote in my original post is a tautology, so it has to be true. The point you are making is that the premise:

if a particular movement pattern requires a certain amount of force to be generated by any particular set of muscle fibers...

is not true. If it were true, then this would reflect a case where there is no redundancy.
Okay, I see where you're going now.

Originally Posted by spacediver
Suppose we accept the fact of redundancy (as in the example I give of the glutes and hamstrings in hip extension). A muscle activation proponent may come along and say:

"See? Because of this redundancy, there is no guarantee that just because a movement looks correct from the "outside", that the proper muscles are being activated. This poor patient, who suffers severe gluteal amnesia, may look like he's squatting correctly, but in fact, the hamstrings are doing a larger share of work than they should be, and the glutes are just going along for the ride without generating the amount of tension they should be. We must spend a few weeks teaching this patient how to activate their glutes, doing glute activation work"

A response to this is that the glutes must be doing work, because they are being stretched during the eccentric phase of the squat, and they will therefore actively contract during the concentric phase. This is the same argument Rip makes in his book when discussing the role of the adductors in the squat (top right paragraph, page 48 in SSBBT 3rd edition).

So now that you've responded this way to the muscle activation specialist, suppose he then replies:

Well just because a muscle lengthens doesn't mean it generates its own tension when it shortens (and they give the example of passive extension of the elbow joint without any tension generated in the triceps). My question is:

"How does one best respond to this final objection?".
There's no point in arguing with these quacks, but here are two points:
1) There is neuromuscular redundancy, but as the load goes up, more motor units that could contribute do. Then there are fewer ways to generate the net force to lift the load.
2) The motor system is going to also trend toward the path of least resistance for energy conservation. The most mechanically advantaged muscle and motor units are going to be used first in a given movement.

Unless you interfere with it somehow, the glute is just going to contract when you need it to.

Even laying aside the absurdity of the supposed "severe gluteal amnesia," it's their proposed solution that is the most ridiculous. The note E occurs with high frequency in Beethoven's 'Fur Elise,' so it must be critical to the piece, right? Now let's spend several weeks striking the E key with the right ring finger on the piano so we can master the song. The muscle activation specialist's program is no less silly than that...

10. Originally Posted by dfclark68
Unless you interfere with it somehow, the glute is just going to contract when you need it to.

Even laying aside the absurdity of the supposed "severe gluteal amnesia," it's their proposed solution that is the most ridiculous. The note E occurs with high frequency in Beethoven's 'Fur Elise,' so it must be critical to the piece, right? Now let's spend several weeks striking the E key with the right ring finger on the piano so we can master the song. The muscle activation specialist's program is no less silly than that...
Excellent.

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