Horizontal force production

[Jason Donaldson]

I'm more concerned with strength not being substantially increased for movement ranges outside what those exercises work. We wouldn't expect doing a bunch of rack pulls to greatly improve my strength off the floor right? And we wouldn't guess that someone who only trains half squats is going to have a fantastic full squat. I don't see that it would be particularly unreasonable to note that movements which don't extend beyond 180 degrees of hip angle may not be optimized for the production of a powerful extension at 185-200 degrees of hip angle

I think I see your confusion, Brookfine.

Strength training is geared toward developing the general adaptation of increased strength. We progress the exercises selected on the criteria of those that move the most weight using the most muscle mass through the greatest effective range of motion.

The ROM of the exercises in the program are selected to be effective for what? For building the general strength adaptation. They do not need to be the ROM most corresponding to that of the specific activities employing that general strength.

Does that help?

[Maybach]

1) the center of mass is gonna be somewhere a little below my sternum and a few inches from my spine

No, it is not. The center of mass is is going to be located somewhere out ahead of your body towards the thing you are pushing against. It is a point in SPACE, not a point on your BODY. If you are talking about only pushing the weight of your body, then yes, it will coincide with the center of mass of your body. During a horizontal force production event (whether pushing a sled or a person, or sprinting) where is the center of mass located relative to the midfoot? (here, the point where the musculoskeletal system interacts with the stationary earth)

2) The force vector does intersect the center of mass with a big but, but, the force vector is not coming perpendicularly from the ground. In sprinting sports you're going to have a large vertical component, but it will also have a significant horizontal component. When I sprint I come away with a stride that's over 2 meters long and I'll have a vertical oscillation of about 10-20cm.

Yes, the force you are exerting has a horizontal component. It's horizontal component is in fact, directly proportional to the displacement of the center of mass away from directly above the midfoot. This is a consequence of the way the human body works. The musculoskeletal system exerts a force vector pointing from it's contact with the stationary ground directly at the center of mass of the system. The result of this, plus the force of gravity (pointing directly down), is horizontal translation. If the vector points in any other direction than a line pointing straight from the midfoot to the center of mass, the result is not translation, but a rotation. If you push too high on a bottom heavy object, you upend it. This works the same for the unweighted human body. It can be represented as a point at the center of mass, acted upon by gravity and a vector pointing up from the ground at the midfoot contact point. The more horizontal force is produced, the further this point is from the midfoot.

Exerting force not perfectly perpendicular to gravity is a simple matter of body positioning. There is nothing special about the vertical direction except when using gravity as a resistance. The lifts do not train your body to exert forces perpendicular to the ground. Your body does not know the definition of perpendicular. They train them to exert force, full stop.

Attachment 8677

The attachment is not showing the vectors correctly. If the vectors from the foot pointed in the direction indicated, the resultant force would not be horizontal motion, but torque about the center of mass. This diagram implies a moment arm between the feet and the COM. No such moment arm exists in reality (at least, not appreciably. A gait physiologist might disagree.

3) The squat is going to load all muscles but it won't load them in the same positions as you will when sprinting. While everyone has a mental image of sprinters being basically at a 45 degree angle to the ground, however in reality for most of the race a sprinters torso will be vertical and the peak of force production will be from a position where the leg is fully behind the hips and almost straight (see image). This position represents a portion of the ROM that never occurs in any squat or deadlift variation. In fact, the only lift I can think of that does work that extension in any capacity is a power clean, coincidentally the one singular lift that every single sprinter and speed athlete swears by. Bolt famously hated the weight room and this was the one lift he liked.

This is the crux of your error. Strength training does not operate by "strengthening ranges of motion". This is a regrettable approximation arrived at by personal trainers trying to motivate/bully their clients. The human body does not work this way. The adaptations which strength training produces increase force production capacity, which cannot be "abbreviated." A gluteus muscle which doubles the force it produces by contraction will double it's force production capacity even if you strip it off the body and electrocute it (controlling of course for non-muscular improvements to force production.)

I can see however, why you might misunderstand this, because "range of motion" is a principle enforced by many fitness voices, Starting Strength included. But this is not because if you fail to stretch your gluteii to their maximum capacity, they suddenly become weak as kittens when your hip angle dips below 60 degrees. A guy quarter squatting 600 pounds still gets quads that can quarter squat 600 pounds

There are, rather two reasons. First different muscles operate differently at different parts of the lift. The quads are more involved at the bottom of the deadlift, the traps more involved at the top. The Starting Strength lifts (i.e., "normal human movement patterns") are selected such that they take the entire musculature through limit efforts. Abbreviating the proscribed range of motion therefore definitionally leaves a muscle group inadequately stimulated. A high bar quarter squat does not represent a limit effort by the glutes, so they have no incentive to become stronger. The "weaknesses in certain ranges of motion" therefore do not represent the principle that a muscle has ranges of motion that can be strengthened independently, but rather that an abbreviated lift does not produce a full strength adaptation. The SS lifts are selected specifically to require a limit effort from every muscle involved in the force production event. A squat requires a limit effort by the entire system of the legs: therefore, the legs will become stronger in every situation they are in. Even if it is one that barely resembles the actual squat. That's why the squat is done the way it is done. The squat being a "normal human movement pattern" does not necessarily imply that all or even most lower body force production events resemble it (though because of anatomy, they DO), but rather that it represents the maximum force generation potential. Increasing that potential increases all force production the body engages in.

Trying to "load the muscles through a range of motion I use when sprinting" is akin to trying to "load the muscles with a bullet in them so I can be stronger when I'm shot." You need to change the way you think about training.

(The second reason is because abbreviating range of motion can become an undesirable training variable. If a guy takes even his quarter squat to 600 pounds, he might not get strong glutes, but he will get strong quads, because you still need to exert a lot of force to quarter squat 600 pounds. It might even make his real squat go up a little But if a guy starts out full squatting 300 pounds, and ends up quarter squatting 600 pounds...he hasn't really gotten much stronger. This is somewhat orthogonal to your concern, but is probably the most important to the actual insistence on correct form SS has)

I guess we can be more granular: how do I best work my ability to produce maximal force from a position where my hip angle is greater than 180 degrees, particularly how might I do this in a non-explosive capacity?

The squat and the deadlift will do this. It has never been observed that they fail to.

[Brookfine]

This is the crux of your error. Strength training does not operate by "strengthening ranges of motion". This is a regrettable approximation arrived at by personal trainers trying to motivate/bully their clients. The human body does not work this way. The adaptations which strength training produces increase force production capacity, which cannot be "abbreviated." A gluteus muscle which doubles the force it produces by contraction will double it's force production capacity even if you strip it off the body and electrocute it (controlling of course for non-muscular improvements to force production.)

I can see however, why you might misunderstand this, because "range of motion" is a principle enforced by many fitness voices, Starting Strength included. But this is not because if you fail to stretch your gluteii to their maximum capacity, they suddenly become weak as kittens when your hip angle dips below 60 degrees. A guy quarter squatting 600 pounds still gets quads that can quarter squat 600 pounds

This was extremely enlightening, my apologies for not getting back to you on this earlier. I read it and I really want to accept this premise, but I have a few tiny questions.

We know fascicles within a given muscle have different lengths, especially flared muscles like traps, and fat ones like glutes. There's also a lot of literature (1) that talks about differences in force production relative to degree of lengthening from the muscle down to the sarcomere level. We also know the damage that any component at any scale recovers from correlates with where encounter the highest degree of force (2).

If damage is proportional to degree of force, and different fasciles are going to be reaching different percentages of their peak length at different points (3) aren't we going to be inducing more damage to different fasciles at different parts of the movement?

Not trying to be disruptive here for the record, I'm more trying to get a good mental framework so I can hopefully stop annoying you guys.



(1) Frontiers | Stimuli for Adaptations in Muscle Length and the Length Range of Active Force Exertion—A Narrative Review
(2) Review. Use it or lose it: Multiscale skeletal muscle adaptation to mechanical stimuli - PMC
(3) The cross sectional muscle area increases during contraction as volume remains the same, but while fasciles with relatively linear paths are going to change their length linearly according to the length of the whole muscle, fasciles that are on the exterior of a muscle belly also will change length non-linearly in order to negotiate the increased path length around the thickened belly

[Jason Donaldson]

This was extremely enlightening, my apologies for not getting back to you on this earlier. I read it and I really want to accept this premise, but I have a few tiny questions.

We know fascicles within a given muscle have different lengths, especially flared muscles like traps, and fat ones like glutes. There's also a lot of literature (1) that talks about differences in force production relative to degree of lengthening from the muscle down to the sarcomere level. We also know the damage that any component at any scale recovers from correlates with where encounter the highest degree of force (2).

If damage is proportional to degree of force, and different fasciles are going to be reaching different percentages of their peak length at different points (3) aren't we going to be inducing more damage to different fasciles at different parts of the movement?

Not trying to be disruptive here for the record, I'm more trying to get a good mental framework so I can hopefully stop annoying you guys.



(1) Frontiers | Stimuli for Adaptations in Muscle Length and the Length Range of Active Force Exertion—A Narrative Review
(2) Review. Use it or lose it: Multiscale skeletal muscle adaptation to mechanical stimuli - PMC
(3) The cross sectional muscle area increases during contraction as volume remains the same, but while fasciles with relatively linear paths are going to change their length linearly according to the length of the whole muscle, fasciles that are on the exterior of a muscle belly also will change length non-linearly in order to negotiate the increased path length around the thickened belly

Too many people have built too much muscle mass using abbreviated ranges of motion, and without building weirdly proportioned muscles to conclude that these specifics you cite have much to do with where within the muscle growth occurs....

You are looking for micro-level details as to the mechanisms by which strength adaptation occurs. I submit to you that this is all extremely speculative. It is essentially impossible to observe these effects in vivo as they occur, and as Rip, Dr. Bradford, Dr. Sullivan, and Dr. Santana (among others) have pointed out at length, the "studies" trying to figure out these mechanisms have a list of problems as long as your arm.

What Rip, et al. have going for them is decades of amalgamated phenomenology. To what degree damage to the muscle occurs during the stress of exercise, by what mechanism this induces recovery and its strength adaptation, on what scale this is localized in the muscle, and so on...these are intriguing questions, but they are in no way necessary to answer in order to know how to train in order to increase strength. The two-factor model is a distillation of experience, filtered through rational analysis. It provides accurate prediction. It informs effective training. We may not know the manner in which adaptation occurs, but we definitely know how to make it occur, and with high efficiency.

By contrast, approaches like swinging a heavier bat to become a harder hitter, doing unstable surface exercises to get better at projecting force in unstable positions, and yes, exercising by exerting force horizontally to get better at moving horizontally all start with what I might call a purely rational approach. It's like the ancient Greek theory on the four elements - it explained some things in a logical framework, and reasoned more or less coherently from some assumptions, but it ultimately can't stand up to scrutiny, because it's FALSE. Rocks don't fall faster than feathers because their higher proportion of earth is attracted to the ground below, and feathers don't fall slower because their greater proportion of air is attracted to the sky above. Both types of errors have an internal consistency, which is necessary for a true framework, but not sufficient. The internal consistency must proceed from sufficient true assumptions for the system to correspond with observable reality.

Short answer to your post: Who knows how it works at the micro-level? But we know that it does work overall.

[Maybach]

Well first, "muscle damage" as a mechanism to drive growth has been more or less roundly debunked. The most you can say is that it often corresponds to a maximum of mechanical stress during a lift.

The physiology of muscle hypertrophy is quite poorly understood. We know pretty much that it occurs in response to force production demands, but that's about it. I'm sure you're familiar with the finding that sprinters all have psoas muscles that are larger than average, but this is mostly genetic and doesn't necessarily correspond to what we know about the physiology of running. Why does this muscle vary the most in size between gifted sprinters and the normal population? We don't know besides some very fuzzy gair physiology. Eddie Hall has similarly bizarre things going on: his biggest outlier is his sartorius muscle, which is obscure enough that even bodybuilders don't even talk about it.

The point is that even in the much more well understood lavele of the musculoskeletal system, our model of which muscles are "worked" differs quite substantially from which muscles "grow." Which is to say we don't really have a model of muscular hypertrophy at the macro level. We have a great deal of *data*, but no actual *model* that fully obtains.

At the level of an individual muscle? We do not have any real clue. The forces at work across an individual muscle depend so much on the muscle and the movement involved, and the bridge between in vitro and in vivo is thus so great, that we likely won't ever without some very novel technology.

We do however have some data, and the data we have indicates a few things that make the model you propose here unlikely. For one, we know that one cannot "sculpt" muscles. Muscular hypertrophy can tentatively be observed to occur unevenly across the body (though this tends to be much more exaggerated in the popular imagination than it ever is in practice. Bodybuilders talking about "lagging" body parts are talking about differences the layman basically can't perceive) but there is no such thing as changing the shape of your muscles by training.

This would seem to preclude the idea that different ranges of motion actually effect the muscle differently. If there were such a thing as "long fascicles" and "short fascicles", then there should be an observable difference between a "long trained" glute and a "short trained" glute. And we don't really see this. We have the classically murky data about sarcoplasm and myofobrils and some other things, but a big glute is basically a big glute. When it becomes ethical to train people for six months, then kill them and analyze their glute under the microscope, maybe this changes.

The real nail in the coffin is the extremely well reported observation that abbreviated ranges of motion do not merely stimulate less hypertrophy, they fail to stimulate hypertrophy [I]at all.[I/] If it were possible to stimulate only the "short fascicles", then a guy should be able to take his quarter squat up to 600 and get great big glutes with no problem. In fact, with *less* of a problem because the "long fascicles" don't need to recovery. Bodybuilders would seek to minimize range of motion wherever possible. Now, there are some crackpots who DO claim things like this (the good Dr. Seedman comes to mind) but their results are either mixed or hard to replicate at the very best.

Rather, that hypothetical 600 pound quarter squatter I mentioned is probably only hypothetical. Either he will have to start inadvertently abbreviating his range of motion further, or he'll just flat stall: the 550 pound quarter squat will be insufficient to product a 555 pound quarter squat. He will, of course, develop up to the point that he can quarter squat 550, but how much of this is actually developed by the training is not straightforward.

Think of it in these terms: if extended ranges of motion could produce strength adaptations in excess of the normally prescribed "effective ROM" of SS, then surely, abbreviated ranges of motion should produce strength adaptations proportional to the abbreviation. But rather, because the abbreviated ROM does not represent a limit effort, we observe hard stalls that are overcome as soon as full ROM is restored. A guy *with* a 600 pound quarter squat has decently strong legs, and can probably full squat 405, but he almost certainly cannot *achieve* decently strong legs by training his quarter squat.

The other part of this is that such specific responses of individual fascicles doesn't much jibe with our model of the muscle. Muscles are extremely well vascularized, and hypertrophy is very strongly mediated by endocrine factors. Note that steroid users don't "target" muscles with steroids: they introduce the steroids to the *blood* via intramuscular injection or oral intake. So it seems likely that the "long fascicles" which work during the abbreviated ROMs are experiencing the same "hypertrophic" endocrine environment they would during an extended ROM. This environment needs to be produced by the ROM which corresponds to a limit force production event. What is this ROM? It is an anatomical phenomenon: the "longest effective" ROM that SS uses.

The disappointing summary to all of this is basically that because the physiology of muscle training so so poorly understood, we have to decline to use any specifics as a model of strength training. What we *can* use is the things we observe to be true about training and ensure that the model obtains with those observations. The SS model obtains uniformly, the model in which different ROMs have unique training effects does not.