What qualifies as work in weightlifting

[Paul1]

If I'm not mistaken from P-chem 20 years ago, there is a thermodynamic definition of work that is different from mechanical work. So in this sense there would be work during an isometric contraction, like pushing against a wall. The energy transfer does not produce movement, in that case.

[JAT]

"If you really care about it that much", this: "The lifter does not benefit from the work the bar does on it because lifter does not store the energy (transfer by work) in a usable form. " is wrong when it comes to stretch reflex.

I said to re-read and understand every word if your really care that much. If you did so, you would have seen the phrase " The bar does work on you and you dissipate the vast majority of the energy it transfers to you (because you are much less useful than a spring)" Note the word majority dissipated because I was taking into account the stretch reflex.

By your definitions of "work done by the bar" (on the lifter) and work done by the lifter on the bar I'm almost certain that the work done by the bar "correlates" with with the energy expended by the lifter: The more work the bar does on the lifter (because it is heavier or moves through longer distance) the more energy the lifter will have to expend to return it to its original state.

The work done by the the bar and by the lifter do not correlate. This can be illustrated by the fact that a lifter benching the bar 3 ft expends a different amount of energy than the same lifter squating the bar 3 ft, yet the work done by the bar can remains the same (assuming the bar moves at the same speeds during the lifts). This is a result of different muscle efficiency, movement efficiency (leverage) and factors I am not aware of.

I'd also bet that in the case of similar lifters using similar programming "energy expended by the lifter" correlates quite well with "muscle increase".

Introducing your new criteria of similar lifter, similar training, similar rest, similar "lift form", sure maybe you get similar results. This does not constrain a relationship between the work done by the bar and the work expended by the apparatus moving the bar.

None of these things are all that relevant to the argument, but for an attempt at a smack-down your attention to detail was weak and you overreached.

Smack-down if you must

It's nice if you know physics, but don't be a douche about it.

I'm not a douche nor am I acting like one. Pretty sure this forum is a pretty straight forward talking one.

People that talk about entropy outside of the appropriate environments mostly do it to sound smart. I found it annoying and said so.

[JAT]

I agree, but I'm not really sure why you posted that, as it's what I already said.

I did not mean to say net work but had already posted by the time I realized. I meant to say net work, positive work, negative work or any work done by the lifter at any moment does not correlates to muscle increase.

Energy expended walking 1000 miles will not increase your squat.

And on this topic net work was assumed to be zero. And zero doesn't correlate with very much.

[Savs]

Disclaimer: This post has nothing to do with strength training, and it will be pedantic as all fucking hell. I am not advocating a new metric, I never was.

This thread seems to be somewhat painful.

You're right about that.

I'm not a douche nor am I acting like one. Pretty sure this forum is a pretty straight forward talking one.

Oh. Ok then... lets get to it.

The work done by the the bar and by the lifter do not correlate.

Said no physicist ever. Correlation functions are non-trivial things. Perhaps it would be wise to brush up on them before casually tossing around the word in a physics context. Did you mean related? In that case, I disagree since the work done by gravity and the work done by the lifter are equal and opposite to one another.

This can be illustrated by the fact that a lifter benching the bar 3 ft expends a different amount of energy than the same lifter squating the bar 3 ft, yet the work done by the bar can remains the same

Work and energy are not the same things.

(assuming the bar moves at the same speeds during the lifts).

Umm, no. Sorry. The work is velocity independent (and path independent in this case; we're using the gravitational field as a conservative field). The work depends only on the starting and ending points.

Back to the beginning of the paragraph:

The work done by the the bar

The bar does no work. Forces do work, and in this case they do work on the bar. On the way down, gravity does work on the bar and the lifter does an equal and opposite amount of work on the bar. Therefore, the bar is at rest at the bottom of the movement (see the work-energy theorem). Similarly, on the way up the lifter does work on the bar and gravity does negative work on the bar so once again no net work has been done on the bar. Considering the lifter, down and up, he/she does no net work, and the same is true for gravity. We can colloquially say the bar does work on the lifter, but it isn't completely correct.

Perhaps English isn't your first language, maybe you were having a bad day, or maybe you were angry and not thinking clearly. In any event, in my opinion sometimes a little humility would serve us better as we type about science, even the simple stuff.

[JAT]

It appears I have in my posts made a few misuse of words by accident. Foremost using the phrase work expended by the lifter when I meant energy expended by the lifter. Not withstanding the argument that I am trying to make is intact. You can refute what is listed below. This will prevent continuous rebuttals by picking up miscommunication and causing a circular discussion.

I will not speculate on your first language or whether your mood is distressed and just stick to the facts of the conversation. I do not care if I have been made wrong. I just care whether I am wrong. So far I've been called a douche and arrogant. I have yet to question or care about the character of those whose posts I disagree with. It is not often that anything on the internet upsets me.

Work is energy transfer. Is energy transfer energy? The better question is, why are we asking this question? To say energy transfer is not energy is like telling someone who has given you a money transfer, "That's not money."

Definition of variables:
F = Force Weight of Bar; H = Height; W = Work; PE = Potential Energy; ɳ = efficiency;
g = accretion due to gravity; a-up/a-down = acceleration of Bar; ΔE = Change in energy;
LA = Lifting Apparatus (Biological or mechanical); Q = energy dissipated
W (Bar Down) = F X H
W (Bar Up) = (- F X H)
Δ W (Bar) = W (Bar Down) – W (Bar Up) = 0
PE (Bar Down) = (- F X H)
PE (Bar Up) = F X H
Δ E (Bar Down) = W (Bar Down) = F X H
Δ E (Bar Up) = W (Bar Up) = (- F X H)
ΔE (Bar net) = W (Bar Down) – W (Bar Up) = 0
W (LA Down) = (-F X H)
W (LA Up) = (F X H)
Δ W (LA) = W (LA Down) – W (LA Up) = 0
PE (LA Down) = F X H – Q ≈ 0 (some small PE resulting from tissue elasticity)
Δ E (LA Down) = ɳ X F (Bar) X [1 – (a-down/g)] X H (note (F X H)+Q =0)
Δ E (LA Up) = ɳ X F (Bar) X [1 – (a-up/g)] X H
Δ E (LA) = Δ E (LA Down) + Δ E (LA Up) – F X H + Q = Δ E (LA Down) + Δ E (LA Up)
Δ E (LA) is not proportional to:
Δ W (LA), W (LA up), W (LA Down), Δ W (Bar), W (Bar Up), W (Bar Down)
ɳ (efficiency) varies across the duration and movement of the lift for many apparatuses and for all biological apparatuses. ɳ typically varies based on enumerable conditions including appendages (arms/legs) used to move the bar, acceleration of the bar, form, leverage, conditioning, muscle structure, etc.

[Mark Rippetoe]

A fascinating and very valuable contribution to what is I'm sure the most broadly interesting thread on the board in the last 5 years. Thank you.