Taller lifter stronger?

[spacediver]

That's an interesting post Savs.

I think the issue here (which is an interesting one) is one of balancing terseness with precision. I can see an argument made for the terse definition if we assume that in most cases, and within limits, individual' potential force application across any specified time/distance will be highly correlated. It would thus often be redundant to say that, in terms of squat-strength-for-3 seconds, Jason is stronger than Alfie, because Jason is almost certainly going to be stronger than Alfie in terms of squat-strength-for-2 seconds.

Also, do we measure displacement in units of distance? Or joint angle? And should we not specify the limits of these joint angles? (a partial squat can be done in any of an infinite number of sliding ranges). Similarly, if there is no displacement, and only time involved (as in an isometric exertion), should we specify the joint angle at which this occurs?

I like to think of strength as more of a "virtue", rather than a dimensional quantity. It's a good first approximation to an underlying set of properties (this set includes the potential force application across the infinite number of distances and times). We can practically say that Jason has a stronger squat than Alfie, and on the rare occasion that Alfie is able to outdo Jason on a tiny subset of force x times / force x distances, we can qualify our claim as needed.

We can think of strength as an underlying property of an organism that clusters together other properties which themselves can have different units. There is thus a statistical element to this definition, in the sense, for example, that an organism that is strong will probably be able to produce high amounts of both forcextime (impulse?), and forcexdistance (work).

[Philbert]

Yes. He got stronger on the bench press. In case there is some trick to the question: There isn't enough information to determine whether or not he got stronger overall. He may have detrained his deadlift by 150 lb, for example.

This question (of lifter anthropometry) and others like it have been raised and discussed many times on these forums. In my earlier post, I stated, "useful for our purposes here" and later stated, "not everyone will agree with the definition." I specifically had the number of reps in mind, although I didn't list that along with other possible objections. I apologize for that.



Yeah, at least. I won't get into the discussion of fairness (if that is actually being discussed). I don't give a shit. I think it's cool, though, that we can do some simple calculations to get some answers about force production for different limb lengths, insertion points, and muscle cross-sectional areas. The question about whether one should consider mechanical work and make that equal across all lifters (or use some other criterion) can be answered using the equations I posted earlier. I won't post that analysis here, maybe we've had enough of that already.



We want to make comparisons, and those require measurements. Yes, "my" definition isn't completely general, but I would describe it as more qualitative than quantitative. There's no formula one could use to plug in values and compute a value for strength.

Rip's definition is more general, but I believe it is incomplete for the purposes of serving as a general, qualitative formula. I'll explain why I believe that's the case, and I'll offer a possible fix. I'm not claiming I'm right. I'm presenting the argument for the sake of discussion and improvement in understanding. If I'm wrong, I'm happy to be corrected. (Maybe happy is too strong a word.)

In Rip's question to me (quoted at the top of the page), and in other places, it seems to me he uses a different definition for strength than the definition: "Strength is the production of force against an external resistance." I have difficulty making sense of the latter definition, and I'm confident I'm not the only one. Earlier, I described the definition as "too vague." I read unrahschuh's post #35 and Rip's response to him in which Rip restated the definition as: "Strength is the ability to produce force against an external resistance." I think the restated definition is better, but I think it's still incomplete.

I think the definition -- even a qualitative one -- ought to have some units, some dimensions; otherwise, it's not at all useful for discussing things like trends , making comparisons, or doing dimensional analysis. I have many times seen people interpret Rip's definition in a way that gives strength units of force (Newtons or pounds). That is, strength equals force. In Rip's example of the crane, he specified the strength of the crane in units of tons (a multiple of pounds). So perhaps units of force are the correct units, and the definition is similar to "Energy is the ability to do work," which is one physics definition of energy. Since energy therefore has units of work, perhaps in the same way strength has units of force.

If a definition describes strength in units of force alone, I will argue the definition is incomplete and thereby incorrect.

Instead of force alone, strength could be defined as force times something else. In this case, the units for strength are not pounds but pounds times either units of time or distance. As mentioned earlier, the question quoted at the top of this post uses units of force times number of reps (which is a function of distance), where in general the number of reps can be any number between zero and let's say 10. One value Rip gave was 550 x 3/4 lb-reps, to choose a number for the partial rep. As another example, The strength standards table uses units of lb-reps. The values are reported in pounds for one rep. An example is 387x1 lb-rep, which is shortened to 387.

It seems to me we therefore have two possible qualitative definitions that are useful for making comparisons. The first definition is one with units of force, and the second is one with units of force times something else. They cannot both be correct. The two entities being defined cannot be the same thing if they have different units. One of them must be wrong.

Lifter 1 squats 405 lb for 1 rep. Lifter 2 squats 405 lb for 5 reps. We say lifter 2 is stronger. If the definition of strength, however, only considers the force, then we can't say Lifter 2 is stronger since both lifters apply the same force to the bar. We'd say the lifters are equally strong, and the first definition of strength gives the wrong answer in this example. Increase the weight so that Lifter 1 squats a quarter rep and Lifter 2 squats the same weight for a full rep. Again we say Lifter 2 is stronger. We could, of course, fix the number of reps and vary the weight, and then we would say the lifter that lifts the most weight is stronger. The units, however, are still lb-reps. Other measurements or displays of strength could involve a force plate measuring force for some duration of time. Again, we could fix the time or fix the force. Either way, the units are lb-sec.

I believe a correct, useful definition should have the correct units. I see two definitions with different units, and I believe they can't both be right. I believe the definition of strength that uses units of force isn't the correct definition. I suggest the following for a general, qualitative definition for strength. I don't know if captures everything, but I think it's an improvement.

The ability to apply force against an external resistance for a specified duration of time and/or through a specified displacement.

No.
The ability to apply force to an external resistance in the context of interest.
While strength is a general quality, which can be developed in one context and used in another, the measurement must always be in a specific context. In the five rep vs one rep squat example above we would expect that lifter 1 would be capable of squatting less than than 405 (perhaps 365?) for 5 reps. If we measure his strength in 5 rep squats and find this to be true we can then say that lifter 2 is stronger in the 5 rep squat. The units are still pounds. If we measure lifter 2's one rep max we may find that he actually cannot lift 407.5 for a single, due to some combination of mental and neurologic factors. In that case we would have to say that in the context of 1rm both lifters are equally strong.
For general purposes of comparing lifters the context of a one rep max after a proper warmup is assumed, when I say Kyle Mask is a stronger squatter than me this is what I mean and what any sane person should be able to understand.
If you try to derive a universal unit which would apply across multiple contexts (pound-reps or some such) you can then formulate an equation whereby you prove in absolute terms that Haile Gebrselassie is stronger than Benedict Magnuson

[Tiedemies]

I think this has reverted to semantics.

Each lift measures the person's ability to produce force along a given trajectory relative to their particular anthropometry. This means that the lifts are not 100% accurate. If there were no limitations to lifting techniques, other than regarding gear, it would at first seem that the measure would be more accurate. But even this is not true.

For example, in strongman competitions, they lift the round boulders. But there bigger hands give an advantage. In deadlift, longer arms and shorter legs give an advantage. And so on. There is no single completely reliable way of measuring who is stronger but a man with a 700 deadlift will with very few exceptions be stronger, when measured with any other lift than a man with a 500 deadlift and there is probably no exception where he is stronger than a man with a 300 deadlift, assuming they have all their limbs in place.

Because there are people whose squats are stronger than their deadlifts, we can't say that a small difference in deadlift means that one is stronger than the other in general. But most likely if all the big lifts are close for persons A and B, then A and B will turn out to be close to equally strong when their strength is measured by some other means, provided that it really measures strength.

If the only thing I knew about persons A and B was that one is 5ft and the other is 10ft, and that they deadlift the same, I'd probably bet on the shorter man squatting more. If they had the same big lifts and we'd put them in a strongman competition, I'd probably bet on the bigger guy.

[Savs]

Philbert, I think it's not just force and see nothing in your post to convince me otherwise.
Tiedemies, no disagreement from me.
spacediver, I have a minor quibble here and there, but otherwise agree with the bulk of what you wrote. I think the partial squat and other issues you raised can be explained by tweaking the definition some more. I think a more-precise definition is the following.

Strength is the ability to produce torque about joints to counteract torques produced by external forces.

Pretty it ain't, but I think it has it's advantages. Dimensions are squared away, time concerns are covered by including "produce", which was in the original definition, and I think the description provides a good starting point for answering questions about human movement and strength.

[Mark Rippetoe]

Sure, Savs, that's what it is. "Torques." What produces the "torques"?

[Tiedemies]

I don't agree with the torque definition. The muscles that produce torque don't produce it for torques sake, but in order for the organism to interact with it's environment. Qualitatively, strength is the ability to produce force against objects that resist, either due to inertia or due to gravity.

This definition should not be under debate.

The torque-production may explain why people with given anthropometry have an advantage in some situations and a disadvantage in others but it is merely a question of how the individual is best equipped to display strength.

The physics of the torque production may be of interest in some considerations about how to best measure general strength but even so, the measure is and always should be, ultimately, about how much force can the individual produce.

[Barry Charles]

Possibly a clarification. Probably not, but...

Force is the rate of change of momentum.

Torque is the rate of change of angular momentum.

That's it. Sav's knows this.

[Mark Rippetoe]

In our system, we defer to mechanical engineering for the terminology regarding forces/mechanics. Our term for leverage is moment, not torque, which is described here:

Couple (mechanics) - Wikipedia, the free encyclopedia

and which refers to a system's rotation about an axis, as with a crankshaft or a half-shaft. Since there are no rotating components like this in the human body, torque is not the proper term. Moment or leverage are the terms we use.

Savs should know this. There will of course be a detailed refutation forthcoming.

[Savs]

In our system, we defer to mechanical engineering for the terminology regarding forces/mechanics. Our term for leverage is moment, not torque, which is described here:

Couple (mechanics) - Wikipedia, the free encyclopedia

and which refers to a system's rotation about an axis, as with a crankshaft or a half-shaft. Since there are no rotating components like this in the human body, torque is not the proper term. Moment or leverage are the terms we use.

This is not to be confused with the term torque as it is used in physics, where it is merely a synonym of moment.

We've discussed this issue (posts #39 and 40).

I will not conform to all physics and/or engineering terminology used by your system; however, when interacting with this community, I should have defined "torque" every time I used it. I haven't done that, and I apologize for the confusion it may have caused. Everywhere I have written "torque", you may replace the word with "moment of force".

Sure, Savs, that's what it is. "Torques." What produces the "torques"?

Torque (moment of force) is determined with respect to a particular point. For a point that is located at the end of a body segment, I described (post #32) the forces (where I used the example of weight W for an external force), their positions with respect to the point, and the resulting torques about that point.

The muscles that produce torque don't produce it for torques sake, but in order for the organism to interact with it's environment.

The interaction is achieved by the rotation of body segments about their joints. A pure translation of a particular body segment requires rotations about multiple joints.

Qualitatively, strength is the ability to produce force against objects that resist, either due to inertia or due to gravity.

Yes, the muscular force produces a torque which in turn creates an action force that can act on a massive object. The resistance of the object to a change in its momentum can be described as a reaction force. In addition to that reaction force and gravitational forces, there are many other possible external forces (external to the body under consideration). Those external forces produce torques about joints.

There will of course be a detailed refutation forthcoming.

No, I'm done.

[Mark Rippetoe]

No, I'm done.

I don't believe you. Can anything be defined simply, for purposes of clarity and understanding? Or must the minutia always clutter the principle?