Impulse/force in pounds for the time frame

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The discussion focuses on calculating the impulse force experienced by a machine lifting a 100-pound weight at a velocity of 2 m/s, particularly during the transition from lowering to lifting. Key points include the necessity of deceleration over a time interval to avoid instantaneous stops, which significantly affects the impulse force. Participants emphasize that the force on the machine can exceed its rated capacity of 125 pounds, especially during rapid changes in motion. The conversation also touches on the differences in force required for lifting versus lowering, with estimates suggesting that higher forces may be needed during quick lifts. Overall, the discussion highlights the complexity of accurately measuring forces in dynamic lifting scenarios.
  • #51
douglas wrote;That's Waynesphysics.Greater energy expenditure doesn't equate greater force.

Yes it does, we covered this in another debatehere on this forum. I thought everyone knows and agrees on this, you only have to go to any nutritional site of book to find this out. You “can not” move faster without “more” force, you “can not” use more force without using more energy, to say other trying to alter physics. WHY are we going here again.

Now for another contradiction.

douglas wrote;You spend more energy in fast lifting because it takes more energy to generate force than to maintain it.

You just said, I quote; Greater energy expenditure doesn't equate greater force you then say and contradict yourself, I quote; You spend more energy in fast lifting because it takes more energy to generate force

douglas wrote;You spend more energy in fast lifting because it takes more energy to generate force than to maintain it.

Yes yes yes, this is what I am and have been saying all along, bingo, yes it “does” take more energy to produce and generate more {more as in the longer you try and use force} and higher force than to maintain it, as in holding the weight half way up, or moving the weight up slow like in the slow repititions.

douglas wrote;It's a purely biological matter.

On a physics site, this is not an answer; it seems a way of getting round, you don’t seem to know. Or do you mean to move faster takes more force and higher force, and thus energy. In the fast you use more power, power is the rate at which energy is transferred, power is the rate at which this work is performed, thus I use more force doing more work and need more energy to do this.

You seem to be thinking energy is the force, it’s not, energy is the energy powering the force/strength of the muscles, and basically the muscles fuel is adenosine triphosphate or simply ATP, Creatine, phosphagen, glycolysis, and oxidative. I repeat, if you only have a certain amount of force/strength, when say lifting 80% {and we all do only have a limited force/strength to use} the faster, or the more of this limited force/strength you use, the faster the total or overall force/strength is used. So use low force/strength slower like you, and it “will” last longer, as it does, as you hit muscular failure about 50% slower doing the repetitions slower.

Wayne
 
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  • #52
sophiecentaur said:
Wayne.
Would you expect to conversation about tennis if you insisted on using the language of football? This is effectively what you are trying to do with your arrogant misuse of the vocabulary. Learn the right terms or go to a less rigorous forum. You may get a (wrong) answer that will make you happy.

I am sorry that my wording sounds arrogant, it’s not meant to be, I am trying my best. But if you “please” tell me what you do not understand, and I will explain it more. I don’t want a wrong answer.

Ok sophiecentaur let me try again.

1,
I imagine you know what am EMG machine is, but just in case, it’s a machine that measures the electrical signals in the muscles. I attached the pads to my muscles and did several tests, all the tests as you see in my earlier posts and a video, showed that there “was more” average muscle force/strength, muscle activity when the weight was moved very fast to very slow. As a physicist, I thought that would intrigue you that it a real life practical experiment showed you was wrong, and that you might want to find out why.

2,
When anybody moves a weight faster, but in this case is using 80% or the persons 1RM {Repetition Maximum or the most weight a person can lift up for a full repetition one time} “you” are saying that the person does not use more of the total or overall force they have, {and we all do only have a limited force/strength to use, and when using 80% its about 15 seconds or more} when moving it faster, am I right there ? If so, as this is what you’re saying, how when we only have a limited amount of force to use, does the person moving the 80% as fast as he can, hit muscular failure nearly twice as fast ? Or in other words the person moving the fastest, moves the weight faster, for more distance in the 50% less the time frame then the slow, thus his limited temporary force they have has been used up faster, but you are saying it’s not ? But then again you do say that the energy is used up faster, but not the force, please, this seems a contradiction to me. As if you’re using more energy, you “must” be using more or a higher amount of force that you have, right ? If not, why would you use more energy if you not using more of the limited force, or a higher force, of the limited force ?

If that’s got a bit complicated, and it has, let me explain a little different.

Clone 1 and 2 can lift up 100 pounds in 4 seconds, and lower the 100 pounds in 4 seconds 4 repetitions/times = 32 seconds, then they have hit muscular failure. {meaning they cannot lift the weight again, until the force, in this case the muscles have got they temporary force back, as the muscles need to replenish they energy supplies}

However, if Clone 1 and 2 lift up 100 pounds in 1 second, and lower the 100 pounds in 1 second, they “will” hit muscular failure far far far faster, in roughly 8 repetition or 16 seconds 4 times.

Does not this mean that when the Clones were lifting faster, they were using up more of the temporary total/over force they had, and faster ? You saeem to be saying no ? So why do they fail at diffrent times lifting the weight at diffrent speeds ?

3,
Also, you seem you be saying that it takes the same total/overall force/strength to move a weight a 1000mm and only a 166mm. If the faster accelerated the weight for just 60% 600mm, that would mean you’re saying that it takes the same force to accelerate a weight a 600mm and to move it at a constant velocity only 166mm. To me that’s saying F = ma is wrong. Also, power is the rate at which energy is transferred, power is the rate at which this work is performed, thus I use more force doing more work and need more energy to do this.

4,
Do you, agree, that the faster you move something with a force the more or the faster the energy is used. I think you will say yes, as we cover this in another debate, to which Douglas did admit he was wrong on that one.

5,
Can you have more power with the same amount of force ?

Wayne
 
  • #53
waynexk8 said:
On a physics site, this is not an answer;

Wayne

Actually, it's a very reasonable answer.

I think it's clear that you don't want a Physics site. What you want is a 'Chew the Fat site' in which no-one really knows what they're talking about but everyone has a good time playing with 'Science Sounding Words'. I'm afraid that PF is not like that. Take a look at the majority of other threads and see how people 'behave themselves' correctly, scientifically.

Like I said earlier, it's GIGO.
 
  • #54
@Wayne
I just read your long post. Your insistence on using terms wrongly can only be regarded as arrogant - when you have been told so many times what the right terms are. You equate force / strength / energy at every opportunity which makes the accompanying reams of stuff meaningless.
What's the point in saying that you're sorry if you continue to say the same old rubbish. You seem to want to pick holes in the explanations given by Douglass and others when they / we have no real idea what question you are actually asking. If you say that reading a Physics textbook is beyond you then how could you think that you would understand and be qualified to argue with what you read here?

I should just turn on your EMG /ESP /SPQR machine and enjoy reading the figures it shows you. That's what you paid your money for. Aim at making them higher (or lower) and see if you feel fitter / stronger as a result. Enjoy things at that level. No one will argue with you or get exasperated.
 
  • #55
sophiecentaur said:
I should just turn on your EMG /ESP /SPQR machine and enjoy reading the figures it shows you. That's what you paid your money for. Aim at making them higher (or lower) and see if you feel fitter / stronger as a result. Enjoy things at that level. No one will argue with you or get exasperated.

I stopped reading Wayne's posts.He has created a world where "you use force from the temporary available force" whatever that could possibly mean.

As for his EMG machine,he has stated that it doesn't give figures.It only gives the Root Mean Square values of the recorded electrical signal.So the numbers that his machines gives are the 70% of the peak recorded values.
Obviously with fast lifting the peaks of the fluctuated force are much higher than slow lifting so the Root Mean Square will also be higher.
 
  • #56
sophiecentaur said:
An EMG may not be Waynephysics but, without reading about what it claims to do, I have to assume it is EMGPhysics which may not be real Physics at all. It wouldn't be the only thing that's been sold on dodgy Science now, would it? Do you have a link about it?

Hi there sophiecentaur,

The Electromyography, EMG machine has been around for some time, in the medical Would it’s as well know as a Kidney machine, but its far far far more widely used, and used all Universities and medical sports science facility’s, its “NO” gimmick, it “DOES” measure the electrical signals that the muscles give out while at rest and exercise. It’s “ALWAYS” used in the studies of Kinology and Biomechanics.

http://www.google.co.uk/url?sa=t&rc...ErnCDx9vBBJgACT0w&sig2=llkClBp3LlPMSx1wQ9VEsg

http://www.google.co.uk/url?sa=t&rc...ErnCDx9vBBJgACT0w&sig2=llkClBp3LlPMSx1wQ9VEsg

Here is the one I bought.

http://www.tensmachines.co.uk/NeuroTrac-ETS-EMG-For-the-Professional_p_133.html

So please, as this gives out a reading of the fast average far higher every time, on its set time, could you please, or should I say hopefully comment more on why the physics equations are wrong.

Please for one moment could we just pretend we all just meet and you just heard of the debate. As too me, if I you or anyone else lifts say 80% of the 1RM, 6 times up and down say in the bench press, in the same time frame as lifting the weight 1 time up and down, it just seems that without even thinking about it, that you just have to use more force/strength to lift it up and down 6 times.

1,
More Power, the rate at which energy is transferred/used, but we all agree on this.
2,
More Work, but we all agree on this. As the fast has moved the weight 1000mm to the slow 166mm, and accelerated the weight 600mm. Since work is defined as a force acting through a distance, the fast as used more work/force acting though a distance ?

3,
You always fail faster about 50% faster in the faster repetitions, so if you fail faster, you “HAVE” used up your temporary force/strength, as you hit muscular failure faster thus you cannot lift the weight anymore. To me, if both Clones started the fast and slow lifting at the same time, as the slow Clone are still lifting the weights when the fast Clone has hit muscular failure and unable to lift the weight anymore, this “is/seems irrefutable, or categorically right to me, and I am not trying to sound smug or anything here, but if the slow Clone is still moving the weight, then the fast Clone “has” used up more overall or the total force/strength they had faster, if you see my point, please do you see what I am saying here ?

4,
EMG state you use more muscle activity when moving anything faster.

5,
Can you have more power with the same amount of force ?



sophiecentaur said:
You say you would "rather talk Physics" but you seldom actually do. That's my point. You talk your own home-brewed version which is not compatible with the real stuff.

I am trying my best, and have come here to learn the talk of physics, however, still you have not said what you don't understand what I am saying.


Thank you again for your time.


Wayne
 
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  • #57
You say you have come to "talk Physics" but you refuse to do just that. You have your own brand of vocabulary, a lot of which has nothing to do with Physics. I'm sorry but several of us have told, on many occasions, you that what you say is not understandable because you use meaningless combinations of a random set of words that you haven't defined.

That machine of yours is just telling you something about muscle activity and, hence, about the Energy that your Muscles are transferring. It tells you nothing about the amount of (and here I am using the term in the correct way) Work Done on the weights you are shifting. You want there to be a definite relationship. There is no reason why there should be, in general. It's often quite clear when you're doing more useful work and less work work - for instance, when running uphill with a pack and the EMG would probably agree. But when you are lifting weights, holding them and lowering them, there can be no useful connection. Why do you insist that you want one?
You won't accept that this is just not Physics. Proper Physics equations will not be "wrong" when applied to the right situation. This is just not one of those situations.

There are questions in the above list that you could answer for yourself just by looking at wikipedia and there are some which no one could answer because they don't relate to Physics.
 
  • #58
sophiecentaur said:
Actually, it's a very reasonable answer.

I think it's clear that you don't want a Physics site. What you want is a 'Chew the Fat site' in which no-one really knows what they're talking about but everyone has a good time playing with 'Science Sounding Words'. I'm afraid that PF is not like that.

No I definitely do not want that, I only look for the truth, that why we came here.

sophiecentaur said:
Take a look at the majority of other threads and see how people 'behave themselves' correctly, scientifically.

Like I said earlier, it's GIGO.

But I am behaving myself, I don’t know what you mean there, I have been polite all along, all I said was a straight forward scientific question, AND then put the reasons with proof, evince and facts why I think the fast uses more overall or total force/strength, like in 1 to 4 above, here is the question again, I don’t understand what’s wrong with it, if you don’t understand or think I ask it the wrong way, I would please like to know. As I do not want to get on anyone nerves, and as you say, I don’t want to piss you off. I just cont get why all this other stuff other than the debate is going on, ok, my Grammar is not that good, but surely you don’t hold that against me, as all spelling is fine.

Weight used roughly 80% of the persons 1RM. {Repitition Maxumun, or the most weight you can lift up once} Lift/exersice, bench press, {but it could be any exersice} 20 inch concentric and 20 inch eccentric.

Fast, 6 reps at .5/.5 = 6 seconds = 240 inch, or/and 24 reps at .5/.5 = 24 seconds 5760 inch.

Slow, 1 rep at 3/3 = 6 seconds = 40 inch, or/and 4 reps at 3/3 = 24 seconds = 160 inch.

Question,
As you only have a limited {as in time} temporary amount of force/strength available to lift 80% at both velocities, as you force/strength will temporary run out, which velocity will use the most overall or total force.

My debate/defence for the faster repetitions is as follows.

1,
More Power, the rate at which energy is transferred/used, but we all agree on this.
2,
More Work, but we all agree on this. As the fast has moved the weight 1000mm to the slow 166mm, and accelerated the weight 600mm. Since work is defined as a force acting through a distance, the fast as used more work/force acting though a distance ?

3,
You always fail faster about 50% faster in the faster repetitions, so if you fail faster, you “HAVE” used up your temporary force/strength, as you hit muscular failure faster thus you cannot lift the weight anymore. To me, if both Clones started the fast and slow lifting at the same time, as the slow Clone are still lifting the weights when the fast Clone has hit muscular failure and unable to lift the weight anymore, this “is/seems irrefutable, or categorically right to me, and I am not trying to sound smug or anything here, but if the slow Clone is still moving the weight, then the fast Clone “has” used up more overall or the total force/strength they had faster, if you see my point, please do you see what I am saying here ?


4,
EMG state you use more muscle activity when moving anything faster.

Wayne
 
  • #59
sophiecentaur said:
You say you have come to "talk Physics" but you refuse to do just that. You have your own brand of vocabulary, a lot of which has nothing to do with Physics. I'm sorry but several of us have told, on many occasions, you that what you say is not understandable because you use meaningless combinations of a random set of words that you haven't defined.

Is not force a push or pull ? Is not distance inches or other ? Is time, as in seconds or other ? “Please” I do not understand what you don’t understand, or what I am asking wrong, please could you either tell me what you don’t understand, or how I am saying it wrong ?

sophiecentaur said:
That machine of yours is just telling you something about muscle activity and, hence, about the Energy that you’re Muscles are transferring.

This machine is “NOT” telling me the energy I am using, its telling me the muscle “activity” as in Newton’s used, the machine measures this in μV. Do you know what I force plate is, it basically does the same thing. Electromyography (EMG) is a diagnostic procedure to assess the health of muscles and the nerve cells that control them (motor neurons).
Motor neurons transmit electrical signals that cause muscles to contract. An EMG translates these signals into graphs, sounds or numerical values that a specialist interprets.
An EMG uses tiny devices called electrodes to transmit or detect electrical signals. During a needle EMG, a needle electrode inserted directly into a muscle records the electrical activity in that muscle. A nerve conduction study, another part of an EMG, uses surface electrodes — electrodes taped to the skin — to measure the speed and strength of signals traveling between two or more points. EMG results can reveal nerve dysfunction, muscle dysfunction or problems with nerve-to-muscle signal transmission. An electromyography detects the electrical potential generated by muscle cells when these cells are electrically or neurologically activated. The signals can be analyzed to detect medical abnormalities, activation level, recruitment order or to analyze the biomechanics of human or animal movement.

http://www.nlm.nih.gov/medlineplus/ency/article/003929.htm

Please sophiecentaur, we need to clear this up first, the EMG reads up muscle activity, not the calories you’re using.

http://www.youtube.com/watch?v=B8gtp...ofilepage#t=3s


http://www.youtube.com/watch?v=pd0ZA...ofilepage#t=1s

sophiecentaur said:
It tells you nothing about the amount of (and here I am using the term in the correct way) Work Done on the weights you are shifting.

Yes is does, and this is a well known fact, as if someone is thought to have muscle atrophy, or disuse atrophy, is defined as a decrease in the mass of the muscle; it can be a partial or complete wasting away of muscle, these machines are used.

sophiecentaur said:
You want there to be a definite relationship. There is no reason why there should be, in general. It's often quite clear when you're doing more useful work and less work work - for instance, when running uphill with a pack and the EMG would probably agree. But when you are lifting weights, holding them and lowering them, there can be no useful connection. Why do you insist that you want one?

Right now I am maybe understanding you here. As I think of when I lift a weight up and down as strength used, and physics calls this the force used, as force is a push or pull, so that’s why I said force/strength. However are you saying I have to call force/strength work ? But I thought work is the force times the distance through which it acts, and if a constant force pushes on a object that moves in the direction of the force, then the work done by this force, so the force is doing the work, and the force in this case in the strength of my muscles.

sophiecentaur said:
You won't accept that this is just not Physics. Proper Physics equations will not be "wrong" when applied to the right situation.

Very true, but have all the variables been added in, I don’t think so, please read this, look at this from 5.00 min, it states I am right.



Fast
P = 695
F = 579
V = 192

Slow
P = 649
F = 546
V = 161

Please also read chapter 4, just the first 2 pages, it says like I have been trying to say all along, these forces that I talk about cannot be easily equated with physics.

http://www.findphysio.com/E-books/Biomechanical%20Evaluation%20of%20Movement%20in%20Sport%20and%20Exercise.pdf



sophiecentaur said:
This is just not one of those situations.

I think it is, as how do you explain I fail faster in the faster repetitions, thus I “HAVE” used up my force faster than the slow ?

sophiecentaur said:
There are questions in the above list that you could answer for yourself just by looking at wikipedia and there are some which no one could answer because they don't relate to Physics.

I have tried to learned physics a little, this may not mean much to you, but I can work out the power myself, see below, but force is far harder.

To determine the force we will need to figure out what the weight of the barbell is (W = mg = 91 kg x 9.81 m/s? = 892 kg.m/s? or 892 N). Now, if work is equal to Force x distance then, U = 892 N x 1.85 meter = 1650 Nm.

Power, takes time into consideration. If for example, it took .5 seconds to complete the concentric lift, then the power generated is 1650 J divided 1.7 s = 3300 J/s.

If it took 2 seconds to complete the concentric lift, then the power generated is 1650 J divided 2s = 825 J/s.


power = force {strength} x velocity. The force is greater if the SPEED is increasing. If the speed is increasing then the weight is accelerating.

Again, the force generated by the muscles is given by the following: F=mg + ma. The first term on the right (mg) is the load the gravitational contribution. The second term on the right (ma) is the contribution due to the acceleration.

If the speed is constant then a=0 and F=mg...equal to the load. If the speed is increasing, then a is not zero and F=mg + ma.

This is Newton's 2nd Law. It cannot be refuted. At least not in this Universe. In the equation F=mg + ma the speed is irrelevant in the first term on the right (mg=load). But it is not irrelevant in the second term (ma). If the speed is increasing, then there is a non-zero acceleration and a=v/t. A CONSTANT acceleration results in a force. This force is added to the load (mg). Acceleration is a change in SPEED.

Wayne
 
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  • #60
waynexk8 said:
This is Newton's 2nd Law. It cannot be refuted. At least not in this Universe. In the equation F=mg + ma the speed is irrelevant in the first term on the right (mg=load). But it is not irrelevant in the second term (ma). If the speed is increasing, then there is a non-zero acceleration and a=v/t. A CONSTANT acceleration results in a force. This force is added to the load (mg). Acceleration is a change in SPEED.

Wayne

Great!For the first time you used some physics!

So what's the change in SPEED when you start and end at rest as it's done when you lift a weight?
 
  • #61
waynexk8 said:
But I am behaving myself, I don’t know what you mean there, I have been polite all along, all I said was a straight forward scientific question, AND then put the reasons with proof, evince and facts why I think the fast uses more overall or total force/strength, like in 1 to 4 above, here is the question again, I don’t understand what’s wrong with it, if you don’t understand or think I ask it the wrong way,
Wayne

Yes, you are being perfectly polite, which is why we continue to converse with you. However, your initial question was not complete and was not asked in Scientific terms. That was the "behaviour" I was referring to.

From your first post:
"But what would be the impulse/force on/from the components/parts if the weight was lowered at the above vilocity, and for how long in 10ths or whatever in time would that higher force have to be until the normal acceleration forces of the lift at rest."

Impulse and force are two different things. That's why two different words are used in Physics.
Likewise, for Force and Strength. So you ask about the relationship between one, non specific quantity and another, non-specific quantity. Is that scientific?

You claim that your machine tells you the force involved (in N) but then say that it reads electrical activity in μV. When you 'tense up' your arm, there is no net force at all (it stays still, in its original position) but there is loads of muscle activity, as your machine would show, but the antagonistic muscles are producing equal and opposite force. So there's no direct connection between muscle activity and force produced. That is unless you have electrodes on every muscle group and the machine can do some complicated 'addition' of the effects of all the muscles.

You are still after some relationship between that muscle activity and the measurable work done on a weight when lifting it. But if it's possible to have loads of muscle activity and Zero work done, then there clearly is not one. Can you not accept that?
There is really no more to be said on the topic (except for another acre of figures about rep rates and pounds lifted).

I can only suggest that you approach the manufacturers of your machine and ask them for their opinion. They may well be more prepared to speak you language as it is in their interest to sell as many of those machines as they can. I think they will tell you that the machine gives a good indication of how much energy the muscles are transferring and / or the forces. I have no problem with that (the neurological application of the machine seem very worth while). They may even launch into some link between that and the mechanical work done. That will make you happy. Great, but it won't make the Science any more valid.
 
  • #62
sophiecentaur said:
Yes, you are being perfectly polite, which is why we continue to converse with you. However, your initial question was not complete and was not asked in Scientific terms. That was the "behaviour" I was referring to.

Ok see your point. Sorry I asked it in layman’s terms, but people have got to start somewhere.

sophiecentaur said:
From your first post:
"But what would be the impulse/force on/from the components/parts if the weight was lowered at the above vilocity, and for how long in 10ths or whatever in time would that higher force have to be until the normal acceleration forces of the lift at rest."

Yes, that was quite a bad post.

sophiecentaur said:
Impulse and force are two different things. That's why two different words are used in Physics.

Yes I see that, here is my interpretation, hope you comment. I would say Impulse is a force acting on an object over a short period of time; like in the peak forces in my repetitions, as when I am lowering on the eccentric the weight, at say 2m/s for 20 inch, I then have to use my highest force I can in Milly seconds to slow, stop and restart the weight force the concentric. If I was using ? 80 pounds, I “think” the impulse force ON my muscles for say a tenth of a second could be from 120 to 160 pounds ?

Then to me the rest of the concentric lift is the force used by the muscles to lift. Both are forces but one is the fast impact force, then there is the lower force to carry on the lift ?

This “very” high impact/impulse force, puts huge tensions on the muscles, and is a BIG part of this debate, as I say that the very high impulse with the high forces from the accelerations cannot be made up or balanced out by the lower forces of the slow repetitions. As not only do the muscles doing the fast have higher forces on the accelerations, they have the “EXTRA” forces from the say tenth of a second huge impact/impulse forces. I am sure D. has not added these in, actually I know he has not added these in, if you have time could you comment on that as well please, the huge impact/impulse force on the muscles from the fast that the slow does not have, as a small force applied for a long time can produce the same momentum change as a large force applied briefly, because it is the product of the force and the time for which it is applied that is important.

sophiecentaur said:
Likewise, for Force and Strength. So you ask about the relationship between one, non specific quantity and another, non-specific quantity. Is that scientific?

Ok sorry, see your point again.

But is not a force a push or pull, and that’s what the muscles strength does.

sophiecentaur said:
You claim that your machine tells you the force involved (in N) but then say that it reads electrical activity in μV. When you 'tense up' your arm, there is no net force at all (it stays still, in its original position) but there is loads of muscle activity,

Not fully with you on that one sorry, or maybe reading you wrong. As when I tense up my arm with the pads on the moving muscles, let's say the biceps and foararm in the curl or arm flextion, if I just tence those muscles the reading on the machine tells me, if I just hold the weight half way up the machine tells me, and when I miove the weight up and down the machine tells me, and tells me the high signals, with my muscles are producing high force, and the lower end of the signals where my muscles are producing the lower force. So this is a net force, when you tense and when you lift.

sophiecentaur said:
as your machine would show, but the antagonistic muscles are producing equal and opposite force.

No, only the antagonistic do “not” produce equal and opposite force in any barbell exercises, they produce very little force, maybe as little as 5 or 10% the agonist muscles do all the lifting and all the lowering. {actually the lowering or eccentric portion of the lift which the biceps and forearm does, {as well as the concentric} able a person to lower 40% more under control, say lower in 6 second, than the person can lift for their 1RM.

So no the antagonistic muscles are not producing equal and opposite force. As the biceps are the curling or flexing muscles, and the triceps are the extending muscles.

sophiecentaur said:
So there's no direct connection between muscle activity and force produced.

Yes there is, it’s a direct comparison. As if I lift 30% then 80% the readings like the peak force and average force will be far higher.

sophiecentaur said:
That is unless you have electrodes on every muscle group and the machine can do some complicated 'addition' of the effects of all the muscles.

You only need the pads on the lifting muscles, as these are the ones producing the force for both up and down.

Yes the machine does do very complicated equations instantly all the time.

sophiecentaur said:
You are still after some relationship between that muscle activity and the measurable work done on a weight when lifting it. But if it's possible to have loads of muscle activity and Zero work done, then there clearly is not one. Can you not accept that?

Yes I understand the concept of work, if I do not move the weight no work has been done, but there is still muscle activity, energy and force being used.
sophiecentaur said:
There is really no more to be said on the topic (except for another acre of figures about rep rates and pounds lifted).

I find it odd you say that, but after reading the about you might differ.

What about this question then ? I am sure you can talk or understand scenarios outside of physics ? Like other branches of physics, kinology, biomechanics. Or, just thought of this, let’s say your back at university, and you have to do a practical test and scenario for your PhD, and the Lecturer asks you the below, and you have to answer. Or could you just have a go for me, or suggest another way I can ask it, but as a physics adviser, I thought you would like to try and work out how the equations do not add up in the real World tests/experiments as in below ? Please ? As I don’t see how you can step outside the box, as I thought all physics should be tested in the real World after they have been calculated on paper.

The Question.
You always fail faster about 50% faster in the faster repetitions, so if you fail faster, you “HAVE” used up your temporary force/strength, as you hit muscular failure faster thus you cannot lift the weight anymore. To me, if both Clones started the fast and slow lifting at the same time, as the slow Clone are still lifting the weights when the fast Clone has hit muscular failure and unable to lift the weight anymore, this “is/seems irrefutable, or categorically right to me, and I am not trying to sound smug or anything here, but if the slow Clone is still moving the weight, then the fast Clone “has” used up more overall or the total force/strength they had faster, if you see my point, please do you see what I am saying here ?

sophiecentaur said:
I can only suggest that you approach the manufacturers of your machine and ask them for their opinion.

These machines are/have been used in Hospitals and sports facilities for years, they are as efficient as your calculator, actually they are calculator/computers in another form. The machines are used as much as the everyday car; they are very well known and used.

http://medical-dictionary.thefreedictionary.com/electromyography

sophiecentaur said:
They may well be more prepared to speak you language as it is in their interest to sell as many of those machines as they can. I think they will tell you that the machine gives a good indication of how much energy the muscles are transferring and / or the forces. I have no problem with that (the neurological application of the machine seem very worth while). They may even launch into some link between that and the mechanical work done. That will make you happy. Great, but it won't make the Science any more valid.

IF, you want to prove your physics equations right, you would need to “try” and answer the question above, and say why the below happens in the real World, as I am in contact; New Scientist Magazine, Physicstoday Magazine and Physics World Magazine. If you could be the first to solve the puzzle of how and why the equations and real World tests on this Phenomena is, maybe you could be in these Mags.

Thank you for your time and help.

Wayne
 
  • #63
So it's more like force is the AMOUNT of "pushing", regardless of the time or distance. Take for example when you press your hands together, there is a certain force, even though there is no distance, and the time has nothing to do with the force, except that it might decrease as you get tired, and will certainly vary somewhat over time.

Consider if you took some dynamic(changing over time) situation and you had a spring in between something apply force and something being moved, you could take a snapshot at any time and determine the force being applied by measuring the spring(assuming you knew it's equilibrium length and spring constant), so time has nothing to do with it.

An impulse has doesn't mean a sudden impact, and doesn't mean its "high"(especially as that is relative to what you are talking about[an elephant can probably handle much higher impulses than a mouse]). You can have an impulse of .0001N*S, taking place over an hour(theoretically), What makes it an impulse is that it is force taking place over time, not just the force we would see in a snapshot, but the measure of that "amount of pushing" for some "amount of time". The same way that acceleration would have a different meaning that acceleration for some amount of time(which is a change in velocity, /delta v[\itex]).
 
  • #64
waynexk8 said:
The Question.
You always fail faster about 50% faster in the faster repetitions, so if you fail faster, you “HAVE” used up your temporary force/strength, as you hit muscular failure faster thus you cannot lift the weight anymore. To me, if both Clones started the fast and slow lifting at the same time, as the slow Clone are still lifting the weights when the fast Clone has hit muscular failure and unable to lift the weight anymore, this “is/seems irrefutable, or categorically right to me, and I am not trying to sound smug or anything here, but if the slow Clone is still moving the weight, then the fast Clone “has” used up more overall or the total force/strength they had faster, if you see my point, please do you see what I am saying here ?

Wayne

Look Wayne...you're an adult person.You MUST be able to understand this.

You don't USE any force from any "temporary available force/strength".You use energy from the available energy to be able to apply force.Apples and oranges.If you're not able to understand those terms and use them correctly,no discussion can be done.

In fast lifting you apply the same average force for the same duration as in slow lifting or even as in just holding the weight hence the force-time integral("overall force") is identical in any case.That's the only known fact.

To answer again your question,you fail faster with fast lifting because the fluctuations of the SAME force require energy at a higher rate.NOT because you use more "overall force".
Physics don't have an answer why this happens.It happens because biology tells us that the fluctuations of force make the muscles more inefficient.
 
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  • #65
@Wayne
Did you ever actually look up the definitions of the words we're all using?
If you haven't yet looked up what Impulse means (in Physics) then you have absolutely no business using it. Likewise for all the other terms we are using. You want Physics so the least you can do is read something about it. I don't think you could distinguish a Physics answer from a BS answer, so far.
 
  • #66
Been ill in bed all day with Sinus problems, will get back to you all.

Thank you for all the replies.

Wayne
 
  • #67
sophiecentaur said:
@Wayne
Did you ever actually look up the definitions of the words we're all using?
If you haven't yet looked up what Impulse means (in Physics) then you have absolutely no business using it. Likewise for all the other terms we are using. You want Physics so the least you can do is read something about it. I don't think you could distinguish a Physics answer from a BS answer, so far.

Did you miss my last post ? I explained what Impulse is. Impulse is force multiplied by the amount of time it used over. Or a force that is applied to an object over a time frame, the overall or total force with time added in.

Ok I will ask you a question,
When I lift a weight from a still start, to a moving, there will be two different amounts of forces, as the impulse force is different. When two objects collide, there will be an impulse; the impulse causes a change of momentum/movement.

1,
I lift 100 pounds from a still start, upwards 20 inch in .5 of a second.

2,
The 100 pounds is being lowered under control from a still stat, lowered at 20 inch in .5 of a second. Immediately at the 20 inch, I lift the 100 pounds upwards 20 inch in .5 of a second.

My point, is that if you separately added the force of lifting a weight up and down 6 times, too adding the force from lifting it up and down constantly 6 times, it would different.

Wayne
 
  • #68
douglis said:
Look Wayne...you're an adult person.You MUST be able to understand this.

You don't USE any force from any "temporary available force/strength".

You “have” to use force to move the weight, so why do you say you, “don't” USE any force from any temporary available force/strength ? You “have” to use force to move the weight

douglis said:
You use energy from the available energy to be able to apply force.

We ALL know you have to use energy to use the forces, we are NOT debating that you use more energy when you move something faster. We are debating the amount of force/strength use. “Why” bring up energy ?

douglis said:
Apples and oranges.If you're not able to understand those terms and use them correctly,no discussion can be done.

I understand that you use energy to create a force, but as I said, we are debating the amount of energy. It’s like how much force/strength must you use to lift 100 pounds one time 20 inch in 20 seconds, and how much force/strength must you use to lift 100 pounds ten times 20 inch in 60 seconds, or debate is similar to that. We are “NOT” on about the fuel/energy {calories} needed to fuel the force/strength. Or are you talking of something else, if so explain why and how you are talking about it.


douglis said:
In fast lifting you apply the same average force for the same duration as in slow lifting or even as in just holding the weight hence the force-time integral("overall force") is identical in any case.That's the only known fact.

1,
EMG states other.

2,
I fail faster in the faster reps, thus I “have” used up my tempery energy/force/strength.

3,
A weight of 100 pounds with an Acceleration of 20m/s, 100 x 200 = 20000N.
100 pounds with an Acceleration of 1m/s, 1 x 200 = 200N.
Ok we have to decelerate in the repping, however this deceleration will be very short, not the 40% as in the 1.5 time of the study.

douglis said:
To answer again your question,you fail faster with fast lifting because the fluctuations of the SAME force require energy at a higher rate.NOT because you use more "overall force".

Again, this is “NOT” an answer; the question is “WHY” the fluctuations of the force require energy at a higher rate. And it’s a direct contradiction on what you said, “IF” the fluctuations of the force require energy higher rate, “why” as you seem to think that the forces make up or balance out, if this was true the energies should/must also make up or balance out. As if my higher high or peck forces as you say take higher energies of fluctuations, then why does not my lowered force on the deceleration make up or balance out ? As it should be high fluctuations high energies, low fluctuations low energies.

Fact is the higher energies are because the higher forces do and cannot be made up or balanced out by your lower forces, as the EMG states.

douglis said:
Physics don't have an answer why this happens.It happens because biology tells us that the fluctuations of force make the muscles more inefficient.

Physics dose have an answer.

Wayne
 
  • #69
waynexk8 said:
Physics dose have an answer.

Wayne

If you're the Expert now, on what Physics can and can't do, then I suggest you answer the question yourself. I have just read your comments on Douglis's post and it is clear that you don't even read his sentences to the end. I have to conclude that you find us all to be totally incompetent in the field of Physics so I suggest you go and find a Forum in which the contributors know enough of the right sort of Physics to satisfy you.
Does it, for one minute, strike you that your whole idea could just be flawed? Your resolute use of the nonsense expression "force / strength" and others, demonstrates that you just don't really want to get to grips with the real stuff. Just why do you keep posting here?
 
  • #70
waynexk8 said:
You “have” to use force to move the weight, so why do you say you, “don't” USE any force from any temporary available force/strength ? You “have” to use force to move the weight

For God's sake...read my whole sentence and try to make your brain work.
You DON'T use force.You use energy to apply force.I "bring up" the energy thing because higher energy usage(as in fast lifting) does NOT equate greater force application.
Apples and oranges.Only in Wayne's world those two mean the same thing.

1,
EMG states other.

Your EMG states greater quadratic mean(RMS) as expected since in fast lifting the force has greater peaks.

2,
I fail faster in the faster reps, thus I “have” used up my tempery energy/force/strength.

Here it is again!Are you able to understand the difference of these three?

3,
A weight of 100 pounds with an Acceleration of 20m/s, 100 x 200 = 20000N.
100 pounds with an Acceleration of 1m/s, 1 x 200 = 200N.
Ok we have to decelerate in the repping, however this deceleration will be very short, not the 40% as in the 1.5 time of the study.Wayne

The acceleration is always exactly balanced by the deceleration regardless the length of each phase.That's why the average force is always equal with the weight.

Fact is the higher energies are because the higher forces do and cannot be made up or balanced out by your lower forces

NONSENSE.
The force-energy relation is NOT linear.The force "balances out" while the energy NOT
.
 
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  • #71
Leave it, douglis, it ain't werf it. :cry:
 
  • #72
sophiecentaur said:
@Wayne
I just read your long post. Your insistence on using terms wrongly can only be regarded as arrogant - when you have been told so many times what the right terms are. You equate force / strength / energy at every opportunity which makes the accompanying reams of stuff meaningless.

In this instance, and force is a basically a push or pull, and that’s what strength is in this instance, a push or pull in the form of strength. So I am calling the force that is pushing/pulling the weight force/strength.

And the energy that supplies the muscles for the force/strength is basically calories, broken down into many chemicals.

sophiecentaur said:
What's the point in saying that you're sorry if you continue to say the same old rubbish.

If you state what I am saying wrong and why, I will read and use or debate.

sophiecentaur said:
You seem to want to pick holes in the explanations given by Douglass and others when they / we have no real idea what question you are actually asking.

If you had/have no idea, you only had to ask.

Question.

Two Clones lift 80% of their 1RM, {Repetition Maximum or the most they can lift up one time} up 20 inch and down 20 inch. So .5/.5 means .5 of a second concentric, {up} and .5 of a second eccentric. {down} One repetition {rep for short} means one concentric and one eccentric, or once up and once down.

Fast,
1 reps at .5/.5 = 6 seconds = distance the weight is moved = 240 inch.
Slow,
1 rep at 3/3 = 6 seconds = distance the weight is moved = 240 inch.

Or the below just for another example.

However this example is a little false, but this needs to be told as it is part of the main of this debate. As if you did do 18 reps fast, you would not only do 3 reps with the slow = 18 seconds, but more like 5 to 6 reps = 3 to 36 seconds, as you always fail faster in the faster reps. This is because in “my” opinion, you have to use more overall or total force to move the weight faster and more distance in the same time frame. Total or overall force means in this instance, as you “only” {and this will apply to a machine or anything as well as human muscles} have a certain amount of available force to use, before it runs out, as you will hit muscular failure quite soon, meaning you cannot pick up the weight anymore as you have ran out of temporary force. So total or overall force means in this instance. As you only have a set amount of force to use in a set time, let’s call that 1000N. So which of the above and below use the most force, or the available force the fastest.

Fast,
18 reps at .5/.5 = 18 seconds = distance the weight is moved = 720 inch.
Slow,
3 reps at 3/3 = 18 seconds = distance the weight is moved = 140 inch.

MY main opinions as to why you must use more total or overall force with the fast.

1,
You fail faster, or hit momentary muscular failure faster on the faster reps, as you “have” to have used up all your temperedly force up and faster, and there is no question that you have not used up all your temperedly force up, because you have, as you hit momentary muscular failure, thus have no force left.

2,
You use more energy, as in calories when doing the faster reps, why do you more energy doing “anything” faster, not just repping weight ? In my opinion it’s because you’re using more force and/or more force faster.

3,
You move the weight with the fast in scenario, 6 times the distance in the same time frame. You accelerate the weight far further then the slow moves it at a constant velocity.

4,
EMG readings state more muscle activity in the faster. This machine is as reliable as a computer in adding equations.

sophiecentaur said:
If you say that reading a Physics textbook is beyond you then how could you think that you would understand and be qualified to argue with what you read here?

All I need is, the fast using the same force, less force or more force and why. And if some say they use the same force, how do they account for 1 to 4 ?

sophiecentaur said:
I should just turn on your EMG /ESP /SPQR machine and enjoy reading the figures it shows you. That's what you paid your money for. Aim at making them higher (or lower) and see if you feel fitter / stronger as a result. Enjoy things at that level. No one will argue with you or get exasperated.

I have come to the physics forum, as if some think physics states the same force, they why does 1 to 4 differ ? I would have thought most physicists would want to know why.

Have you heard of a force plate or platform ? It’s a machine for taking many force reading, like ground force readings from runners, weightlifters and so on. I will either try to buy one or pay for some tests to be done, if this states the fast uses more force, what then, there will be 1 to 5. However I cannot see how anyone could argue with 1.

My opinion is that the higher forces the fast puts out on the accelerations, when the fast is on its lower force and decelerations, the constant medium forces of the slow, cannot makeup or balance out the fast higher acceleration higher forces. They may add on paper, but that’s not real World practical actions which apply in World.

Again, thank you for your time and help, and I have honestly come here to exasperate anyone, all I wanted was a nice quite polite debate.

Wayne
 
  • #73
douglis said:
Great!For the first time you used some physics!

So what's the change in SPEED when you start and end at rest as it's done when you lift a weight?

You did say “speed” and speed is the rate/time at which an object covers distance, or the rate of change of position.

So your slow rep is more of a speed, or constant speed, so as don’t basically have a change in speed {other than the initial acceleration and closing deceleration, you change in speed is basically zero.

“Please” you reason for this ?

As my faster reps have acceleration, and to accelerate an object is to change its speed, I have basically a constant change in speed on acceleration and deceleration.

I ask again, your reason for this please.

Now my questions,

1,
If you cannot move the/a weight, as in the faster reps when you hit momentary muscular failure, this means you do not have sufficient force to move to move the weight, yes you do not have sufficient force or no you do have sufficient force?

2,
If you can move the/a weight, as in the slower reps when Clone 1 has hit momentary muscular failure, in the faster reps, this means you do have sufficient force to move to move the weight, yes you do have sufficient force to move to move the weight or no you don’t have sufficient force to move to move the weight?

3,
Most people would say, yes you do not have sufficient force to 1, and most people would say, yes you do have sufficient force to move to move the weight to 2.

So this means you use up your temporary force faster on the faster reps, meaning you are using more total or overall force up. And faster, right ?


Wayne
 
  • #74
waynexk8 said:
So this means you use up your temporary force faster on the faster reps, meaning you are using more total or overall force up. And faster, right ?


Wayne

Everything is perfectly answered at my last post.I don't know what you can't understand but it's becoming ridiculous.
I'll follow sophiecentaur's advice and leave it.
 
  • #75
No sure if this is to me or all.

Zula110100100 said:
So it's more like force is the AMOUNT of "pushing", regardless of the time or distance.

Agree. However, for working things out you need to add in other quantities.

Zula110100100 said:
Take for example when you press your hands together, there is a certain force, even though there is no distance, and the time has nothing to do with the force, except that it might decrease as you get tired, and will certainly vary somewhat over time.

Agreed.

Zula110100100 said:
Consider if you took some dynamic(changing over time) situation and you had a spring in between something apply force and something being moved, you could take a snapshot at any time and determine the force being applied by measuring the spring(assuming you knew it's equilibrium length and spring constant), so time has nothing to do with it.

Time would have something to do with it.

As the more compressed the spring got the more force needed, and vice versa.

Also, if you were taking about applying muscular force, then time again would come into it.

Zula110100100 said:
An impulse has doesn't mean a sudden impact, and doesn't mean its "high"(especially as that is relative to what you are talking about[an elephant can probably handle much higher impulses than a mouse]). You can have an impulse of .0001N*S, taking place over an hour(theoretically), What makes it an impulse is that it is force taking place over time, not just the force we would see in a snapshot, but the measure of that "amount of pushing" for some "amount of time". The same way that acceleration would have a different meaning that acceleration for some amount of time(which is a change in velocity, /delta v[\itex]).
<br /> <br /> Agreed.<br /> <br /> Wayne
 
  • #76
sophiecentaur said:
If you're the Expert now, on what Physics can and can't do, then I suggest you answer the question yourself.

Never said I was an expert.

sophiecentaur said:
I have just read your comments on Douglis's post and it is clear that you don't even read his sentences to the end.

I have, and answer everything. Please show me what I have not answered ?

sophiecentaur said:
I have to conclude that you find us all to be totally incompetent in the field of Physics so I suggest you go and find a Forum in which the contributors know enough of the right sort of Physics to satisfy you.

I don’t understand why you say that. I asked a polite question, and “gave” 4 reasons why it could be wrong, and NOT once have you had a go at answering them. You seem to want to turn this into a mocking match; I simply do NOT want that. “Please” tell me why you can’t debate/answer my 4 reasons ? You seem to be trying to mock me because I ask a question.

sophiecentaur said:
Does it, for one minute, strike you that your whole idea could just be flawed?

Hmm, not sure there, as it does take a certain force/strength to move an object so and so distance in so and so time frame, so there should be an answer.

sophiecentaur said:
Your resolute use of the nonsense expression "force / strength"

I explained that, however you do not say why you think this is wrong. A force is basically a push or pull, in this instance the force is my muscle strength. If you say why it’s wrong maybe I will agree.

sophiecentaur said:
and others,

What others please. Tell me and I will explain or learn from you.

sophiecentaur said:
demonstrates that you just don't really want to get to grips with the real stuff. Just why do you keep posting here?

I do want to learn, honest.

Sophiecentaur, you don’t know me and I don’t know you, but I can honestly say I did or do not want it to turn out like this, all I want is a polite friendly debate, also I do not get why you do not try and debate/answer my 4 reasons, “OR” answer this question to which I asked before and is full physics.

Can you have more power and the same force in the same time frame ?

Please again Sophiecentaur, thank you for your time and help, and sorry if IO upset you, it was/is not intended.

Wayne
 
  • #77
There you go again with acres of unreadable (and unread) rambling. State your question like everyone else does: in a couple of lines, using the right terms (which you know by now). No one will make sense of that old ramble above.
Admit it, though, you just want an unending chat and not an answer.
 
  • #78
douglis said:
For God's sake...read my whole sentence and try to make your brain work.
You DON'T use force.You use energy to apply force.

We all know you use energy to apply force, no one is debating this ?

douglis said:
I "bring up" the energy thing because higher energy usage(as in fast lifting) does NOT equate greater force application.

You seem to be tying yourself in knots, as you are constantly contradicting yourself.

1,
We all agree that you have to use more energy the faster you do anything in the same time frame.

2,
When you do something faster in the same time frame you “have” to have high/faster/longer accelerations, these high/faster/longer accelerations “must” have higher forces, as you can’t have high/faster/longer accelerations without initial higher forces for the acceleration.

But you say, I quote; higher energy usage(as in fast lifting) does NOT equate greater force application.

3,
So do you think it’s “just” a coincidence that when you have high/faster/longer accelerations to a constant speed, that the energy needed for the high/faster/longer accelerations goes up ? Or do you think it’s because the force “has” to go up for the high/faster/longer accelerations ?

4,
Tell me, as of several months back you stated that you do not use more energy doing anything fast, you then over the debate got convinced you were wrong by someone from this forum, then agreed that you were wrong, and admitted that you have to use more energy when doing anything fast, and in our case lifting weight. Could you please state why you have to use more energy ? Is it a, when the accelerations and force go up, or b, on the deceleration when the force goes down ?

5,
What/why does equate greater energy application in the faster reps, is its not force ?

First on a physics forum, you “NEED” to “state/say” WHY you “think” higher energy usage does not equate greater force application.

douglis said:
Apples and oranges.Only in Wayne's world those two mean the same thing.

I “never” once said they mean the same thing, odd thing to say ?


douglis said:
Your EMG states greater quadratic mean(RMS) as expected since in fast lifting the force has greater peaks.

I have higher peak, and lower lows, please do not forget about the lower lows, as the EMG WILL take these reading to, and average them all up, or do you want to try and forget about my lows when its convenient ?

The RMS also known as the quadratic mean, is a statistical measure of the magnitude of a “varying” quantity. So YOU state that my high forces and my low forces are all balanced out by your medium forces. So if the EMG takes the highs and the lows on my high and low forcers, as you claim they should all balance out, but they do NOT do they ?

RMS It is especially useful when varieties are positive and negative.

It can be calculated for a series of “discrete” values or for a “continuously” “varying” function. The name comes from the fact that it is the square root of the mean of the squares of the values. It is a special case of the generalized mean/average.


douglis said:
Here it is again!Are you able to understand the difference of these three?

I never said I do not know the difference ? Why would you think or say that ? I said, I quote; I fail faster in the faster reps, thus I “have” used up my temporary energy/force/strength.

I fail in the faster reps because I have used my temporary energy up, as in the muscles energy ATP glucose and creatine. And used my temporary force up, push or pull. And used up my strength push or pull.

douglis said:
The acceleration is always exactly balanced by the deceleration regardless the length of each phase.That's why the average force is always equal with the weight.

Why do you “think” its balanced, you cannot say, if it was balanced, why is you energy and distance not made up or balanced out in your slower reps, if you claim its balanced out ?

douglis said:
NONSENSE.
The force-energy relation is NOT linear.The force "balances out" while the energy NOT
.

Again you state something with “nothing” to back it up ? You need to try and explain why the faster reps use more energy, you need to say why and how you think the forces balance out make up but the energy does not ? I say why, but you can not ?

So what if I buy or get tests done on a force plate, and they state what I claim, will you accept your physics equations are missing variables then ?

Wayne
 
  • #79
sophiecentaur said:
There you go again with acres of unreadable (and unread) rambling. State your question like everyone else does: in a couple of lines, using the right terms (which you know by now). No one will make sense of that old ramble above.

Please, just say what you do not get or understand and I will try to explain. I am not sure if I can say it short, as its “need” an explanation. As some things I need to explain, and I did my best trying to, what would you think or me if I left things out and told you later ?

Question short,

I lift a weight 1000mm in .5 of a second, you lift a weight 166mm in .5 of a second, which uses the most force, not the peak force used, but the total or overall force.

Question long as I think it needs more of an explanation as I know more about it.

Two Clones lift 80% of their 1RM, {Repetition Maximum or the most they can lift up one time} up 20 inch and down 20 inch. So .5/.5 means .5 of a second concentric, {up} and .5 of a second eccentric. {down} One repetition {rep for short} means one concentric and one eccentric, or once up and once down.

Fast,
1 reps at .5/.5 = 6 seconds = distance the weight is moved = 240 inch.
Slow,
1 rep at 3/3 = 6 seconds = distance the weight is moved = 240 inch.

Or the below just for another example.

However this example is a little false, but this needs to be told as it is part of the main of this debate. As if you did do 18 reps fast, you would not only do 3 reps with the slow = 18 seconds, but more like 5 to 6 reps = 3 to 36 seconds, as you always fail faster in the faster reps. This is because in “my” opinion, you have to use more overall or total force to move the weight faster and more distance in the same time frame. Total or overall force means in this instance, as you “only” {and this will apply to a machine or anything as well as human muscles} have a certain amount of available force to use, before it runs out, as you will hit muscular failure quite soon, meaning you cannot pick up the weight anymore as you have ran out of temporary force. So total or overall force means in this instance. As you only have a set amount of force to use in a set time, let’s call that 1000N. So which of the above and below use the most force, or the available force the fastest.

Fast,
18 reps at .5/.5 = 18 seconds = distance the weight is moved = 720 inch.
Slow,
3 reps at 3/3 = 18 seconds = distance the weight is moved = 140 inch.

MY main opinions as to why you must use more total or overall force with the fast.

1,
You fail faster, or hit momentary muscular failure faster on the faster reps, as you “have” to have used up all your temperedly force up and faster, and there is no question that you have not used up all your temperedly force up, because you have, as you hit momentary muscular failure, thus have no force left.

2,
You use more energy, as in calories when doing the faster reps, why do you more energy doing “anything” faster, not just repping weight ? In my opinion it’s because you’re using more force and/or more force faster.

3,
You move the weight with the fast in scenario, 6 times the distance in the same time frame. You accelerate the weight far further then the slow moves it at a constant velocity.

4,
EMG readings state more muscle activity in the faster. This machine is as reliable as a computer in adding equations.

sophiecentaur said:
Admit it, though, you just want an unending chat and not an answer.

What I will admit, is I am sick of people not trying to give me an answer, because I seem to have proved them wrong, if you think I have not, then please post an answer and try and refute 1 to 4, is that too much to ask.




Let’s change this around for a minute, and YES I know this is different, but let’s say you ran up to the shop and back, which is uphill, 100m away, as fast as you could 6 times in 300 seconds = 1200m, most people would either not make it, or be totally exhausted. You then walk very slowly to the shop and back one time in 300 seconds = 200m, do you honestly think you have used the same overall or total force, or the same overall or total muscle force ?

I say again, I have not started this mocking type match; I have been polite and only asked questions, and said if anyone does not understand them to ask. All I want is some kind of answer.

Wayne
 
  • #80
waynexk8 said:
I have higher peak, and lower lows, please do not forget about the lower lows, as the EMG WILL take these reading to, and average them all up, or do you want to try and forget about my lows when its convenient ?

Wayne

I didn't even read all the rest you wrote because you're repeating the same NONSENSE that has been answered dozens of times.

The above is the only one that worth answering.
The RMS takes the square root of the mean of the squares of the values.By taking the squares of the values you turn the negative values into positives.
I know you have problems with basic maths but you must have been taught that in high school.For example...-2^2=4 not -4.

So...your EMG turns the "lower lows" into "higher peaks".The RMS is NOT the technical mean that we've been discussing so far...it's the quadratic mean...huge difference.
The RMS(quadratic mean) is exactly the 70% of the peaks...the positive peaks and also the negatives that turned into positive.
Since fast lifting has greater peaks will definitely have higher RMS.

Your EMG maybe fine for comparing the activation of a muscle group between different exercises but is NOT offered for a fast vs slow comparison.
That comparison could only be possible if you'll find the integrated EMG(iEMG) like they did in the push ups studies(and found greater iEMG for the slow push ups!) or as I did at the graphs I mailed you.
 
  • #81
Please see the video stating that more overall, total force was used with the fast rep, but this time the more force was used in "less" time, go from 5 min.



Fast
P = 695
F = 579
V = 192

Slow
P = 649
F = 546
V = 161

Wayne
 
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  • #82
waynexk8 said:
Please see the video stating that more overall, total force was used with the fast rep, but this time the more force was used in "less" time, go from 5 min.

That's an accelerometer.From the change in speed estimates the peak value of the acceleration and then from the equation F=mg+ma finds the peak value of force(Fmax).
Check their site..."Concentric strength(N) = Fmax in the push"
https://docs.google.com/viewer?a=v&...Vseg--&sig=AHIEtbSVGzCSQRrN1crmIrlXybsDwA_Pwg

The "total/overall force" can be found ONLY by using integrated electromyography(iEMG) like they did in the push ups studies.
 
  • #83
sophiecentaur, I was woundering why you did not replly to this post ? As without sounding sarcastic, you got the force produced by the agonist and antagonist wrong, thus i think we need to clear thins up, and the other things.

https://www.physicsforums.com/showpost.php?p=3725969&postcount=63

Could you go from here please;

sophiecentaur wrote;
You claim that your machine tells you the force involved (in N) but then say that it reads electrical activity in μV. When you 'tense up' your arm, there is no net force at all (it stays still, in its original position) but there is loads of muscle activity.

Not fully with you on that one sorry, or maybe reading you wrong. As when I tense up my arm with the pads on the moving muscles, let's say the biceps and foararm in the curl or arm flextion, if I just tence those muscles the reading on the machine tells me, if I just hold the weight half way up the machine tells me, and when I miove the weight up and down the machine tells me, and tells me the high signals, with my muscles are producing high force, and the lower end of the signals where my muscles are producing the lower force. So this is a net force, when you tense and when you lift.



sophiecentaur wrote;

as your machine would show, but the antagonistic muscles are producing equal and opposite force.

No, the antagonistic do “not” produce equal and opposite force in any barbell exercises, they produce very little force, maybe as little as 5 or 10% the agonist muscles do all the lifting and all the lowering. {actually the lowering or eccentric portion of the lift which the biceps and forearm does, {as well as the concentric} able a person to lower 40% more under control, say lower in 6 second, than the person can lift for their 1RM.

So no the antagonistic muscles are not producing equal and opposite force. As the biceps are the curling or flexing muscles, and the triceps are the extending muscles.


sophiecentaur wrote;

So there's no direct connection between muscle activity and force produced.

Yes there is, it’s a direct comparison. As if I lift 30% then 80% the readings like the peak force and average force will be far higher.



sophiecentaur wrote;

That is unless you have electrodes on every muscle group and the machine can do some complicated 'addition' of the effects of all the muscles.

You only need the pads on the lifting muscles, as these are the ones producing the force for both up and down.

Yes the machine does do very complicated equations instantly all the time.



sophiecentaur wrote;

You are still after some relationship between that muscle activity and the measurable work done on a weight when lifting it. But if it's possible to have loads of muscle activity and Zero work done, then there clearly is not one. Can you not accept that?

Yes I understand the concept of work, if I do not move the weight no work has been done, but there is still muscle activity, energy and force being used.


sophiecentaur wrote;

There is really no more to be said on the topic (except for another acre of figures about rep rates and pounds lifted).

I find it odd you say that, but after reading the about you might differ.

What about this question then ? I am sure you can talk or understand scenarios outside of physics ? Like other branches of physics, kinology, biomechanics. Or, just thought of this, let’s say your back at university, and you have to do a practical test and scenario for your PhD, and the Lecturer asks you the below, and you have to answer. Or could you just have a go for me, or suggest another way I can ask it, but as a physics adviser, I thought you would like to try and work out how the equations do not add up in the real World tests/experiments as in below ? Please ? As I don’t see how you can step outside the box, as I thought all physics should be tested in the real World after they have been calculated on paper.

The Question.
You always fail faster about 50% faster in the faster repetitions, so if you fail faster, you “HAVE” used up your temporary force/strength, as you hit muscular failure faster thus you cannot lift the weight anymore. To me, if both Clones started the fast and slow lifting at the same time, as the slow Clone are still lifting the weights when the fast Clone has hit muscular failure and unable to lift the weight anymore, this “is/seems irrefutable, or categorically right to me, and I am not trying to sound smug or anything here, but if the slow Clone is still moving the weight, then the fast Clone “has” used up more overall or the total force/strength they had faster, if you see my point, please do you see what I am saying here ?

sophiecentaur wrote;

I can only suggest that you approach the manufacturers of your machine and ask them for their opinion.

These machines are/have been used in Hospitals and sports facilities for years, they are as efficient as your calculator, actually they are calculator/computers in another form. The machines are used as much as the everyday car; they are very well known and used.

http://medical-dictionary.thefreedic...ectromyography


Originally Posted by sophiecentaur
They may well be more prepared to speak you language as it is in their interest to sell as many of those machines as they can. I think they will tell you that the machine gives a good indication of how much energy the muscles are transferring and / or the forces. I have no problem with that (the neurological application of the machine seem very worth while). They may even launch into some link between that and the mechanical work done. That will make you happy. Great, but it won't make the Science any more valid.

IF, you want to prove your physics equations right, you would need to “try” and answer the question above, and say why the below happens in the real World, as I am in contact; New Scientist Magazine, Physicstoday Magazine and Physics World Magazine. If you could be the first to solve the puzzle of how and why the equations and real World tests on this Phenomena is, maybe you could be in these Mags.

Thank you for your time and help.

Wayne
 
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  • #84
How can the machine distinguish between situations where there are and there aren't antagonistic muscles at work? Are you saying that your machine 'knows' when your arm is moving and when it's stationary? Does it know then you are holding, lifting and lowering the weights?

How can you expect to get a proper answer whilst you still insist on using the term force/strength? Do me a favour and look the individual words up. They describe entirely different aspects of Physics. Which one do you mean when you use that term? Why do you hang on to these deliberately nonsense terms instead of using the right one? You are saying black is white on every occasion.

The very least you could do, if you really do want some sense, is to use the correct terms. Imagine you had a calculator and the + key sometimes gave you a - and the X key sometimes gave you a ÷. You would say it was rubbish, wouldn't you? Constantly using confusing terms is the equivalent to a dodgy calculator.

At least, you could do us all the courtesy of talking the right language. (The language that 11 year old kids are quite happy to learn to use in School.) Don't ask me to help you with this - just look up any word you want to use and see if it actually fits what you want to say. I get the impression that you are not looking anywhere else for your information but just want to be spoon fed by PF. This is unreasonable.

btw, I don't have to justify the Physics Equations in this context. They work fine for everyone but you so I am not out of step here. Give me a proper question (not ten pages of weight lifting jargon) and I can guarantee a good answer. Give me another 'Wayne' question and there will be no available answer from Physics.
 
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  • #85
douglis said:
That's an accelerometer.

It a accelerometer, with built in velocity, power, force and other, the unit uses three-dimensional accelerometer. By measuring body movement in three dimensions (backwards and forwards, up and down, side to side), the body can be tracked in space. The speed (and change in speed) of movement can be used to calculate such things as flight time, number and speed of repetitions and power. Many physical parameters can then be calculated from these parameters.

douglis said:
From the change in speed estimates the peak value of the acceleration and then from the equation F=mg+ma finds the peak value of force(Fmax).
Check their site..."Concentric strength(N) = Fmax in the push"
https://docs.google.com/viewer?a=v&...Vseg--&sig=AHIEtbSVGzCSQRrN1crmIrlXybsDwA_Pwg

Not sure if I get you there, as the fast produced more Newtons, yes ? So more Newtons is more total or overall force, right ? As how can more N be the same ?

douglis said:
The "total/overall force" can be found ONLY by using integrated electromyography(iEMG) like they did in the push ups studies.

integrated electromyography uses RMS, like my machine, I can set it for as many samples as I want. You have to use RMS to perform the integration. Do you know what Integrated means ? Combining or coordinating separate elements so as to provide a harmonious, interrelated whole = RMS.

Calculate the integrated EMG envelope on- and off-line. The integration function incorporates an RMS (Root Mean Square) feature set to operate over a user-specified number of samples. Adjust the RMS time constant by increasing or decreasing the number of samples used to perform the integration. The number of samples used in the RMS integration divided by the sample rate is proportional to the time constant of the integration.

http://www.biopac.com/researchApplications.asp?Aid=41&AF=61&Level=3

Do a search for integrated below, you will find RMS is part or integrated, as RMS has to be used, as RMS = Averaged or root-mean-square (RMS)

Integrated EMG (iEMG) important for quantitative EMG relationships (EMG vs. force, EMG vs. work) best measure of the total muscular effort, useful for quantifying activity for ergonomic research, various methods: mathematical integration (area under absolute values of EMG time series) root-mean-square (RMS) times duration is similar but does not require taking absolute values.

http://uk.search.yahoo.com/r/_ylt=A7x9QV9meiRPvTQAmu9LBQx.;_ylu=X3oDMTE0cTc5aTMzBHNlYwNzcgRwb3MDMgRjb2xvA2lyZAR2dGlkA1VLQzAwMV83MQ--/SIG=12jemp264/EXP=1327819494/**http%3a//www.health.uottawa.ca/biomech/courses/apa4311/emg-p2.pps

Why do you refer to RMS on my machine ? Show me the machine they used in the press up ?

I showed you the those press up studies were flawed, in that it was total muscle activity they took, and as the slow went on for longer.

Wayne
 
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  • #86
waynexk8 said:
Do you know what Integrated means ? Combining or coordinating separate elements so as to provide a harmonious, interrelated whole = RMS.
Wayne

So that is your definition of 'Integration'? It is not the Mathematical definition that is used (and works) in Physics so there is no point in your using the term.
 
  • #87
waynexk8 said:
Not sure if I get you there, as the fast produced more Newtons, yes ? So more Newtons is more total or overall force, right ? As how can more N be the same ?

No...the total/overall force(effect of force over time...impulse) is given by N*s...NOT by N.
The more N means greater peak force as they also state by themselves("Concentric strength(N) = Fmax in the push")

integrated electromyography uses RMS, like my machine, I can set it for as many samples as I want. You have to use RMS to perform the integration. Do you know what Integrated means ? Combining or coordinating separate elements so as to provide a harmonious, interrelated whole = RMS.


Yes...but you must also normalize the raw EMG data in order to integrate.Check the paragraph " materials and methods".It's described pretty well.The equation (1) shows that the integration is done for the normalized data.
http://jmbe.bme.ncku.edu.tw/index.php/bme/article/viewFile/635/839

Anyway...this discussion is meaningless.The fact is that the RMS is the 70% of the peak and naturally higher in fast lifting.End of story.

I showed you the those press up studies were flawed, in that it was total muscle activity they took, and as the slow went on for longer.

Wayne

Those press up studies are perfectly designed...your mind is flawed.
For example...compare the durations and the Total Muscle Activations.

Slow push ups:Duration=101.2 sec...TMA(triceps)=3145.29
Fast push ups:Duration= 84.2sec...TMA(triceps)=2138.91

The duration of the slow push ups is only ~20% greater but the Total Muscle Activation is ~47% greater.This is a direct PROOF that slow push ups have greater muscle activation per unit of time.
We have such a well designed study examining exactly what you're looking for and you're still around forums saying NONSENSE.
 
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  • #88
Back a little later.

This will please S. and D and the rest of the forum, some pure physics for a change.

Could anyone state the Newton’s needed for the below,

1,
From a still start, 80 pounds is moved up 20 inches, in .5 of a second, stops and reverses. Only the Newton’s for the forward.

2,
From a still start, 80 pounds is moved up 3.3 inches, in .5 of a second, stops and reverses. Only the Newton’s for the forward.

3,
80 pounds is being lowered under control at 20 inches in .5 of a second, then when still in full downward motion, it’s moved upward 20 inches, in .5 of a second, stops and reverses. Only the Newton’s for the immediate deceleration, {wherever this may be I would say the last 5%}
stop and forward/upward to stop.

Wayne
 
  • #89
Can't ba answered if you don't know the acceleration, I'm afraid.
Force=Mass X Acceleration
(Then add the weight, in this case)

Are you assuming constant force all the time?
 
  • #90
waynexk8 said:
Back a little later.

This will please S. and D and the rest of the forum, some pure physics for a change.

Could anyone state the Newton’s needed for the below,

1,
From a still start, 80 pounds is moved up 20 inches, in .5 of a second, stops and reverses. Only the Newton’s for the forward.

2,
From a still start, 80 pounds is moved up 3.3 inches, in .5 of a second, stops and reverses. Only the Newton’s for the forward.

Wayne

Again that question.Define the value of force you're interested in.The peak...the average or the "total" force(integration of force in respect of time)?

For the peak force...we need more data.

For the average force...in both cases you start and end at rest.The net change in momentum is therefore zero, which is equal to the net impulse delivered. Therefore, the average force is equal with the weight in both cases...80 pounds or 356N.

For the "total" force...again in both cases is equal with gravity's impulse for .5sec.So...356 X .5=153N*s.
 
  • #91
Calculate the peak force needed to throw a computer out of a window in sheer exasperation!
 
  • #92
sophiecentaur said:
Can't ba answered if you don't know the acceleration, I'm afraid.

Will change to Metric.

Hmm, thought I had put enough information in, as if I am moving the weight 500mm at every .5 of a second, I decelerate for say the last 20% thought you would/could work this out, or am I doing it wrong ? Seems I was wrong interesting.

I am moving the weight on 1, at 1m/s. {m/s 1 meter per second}

I am moving the weight on 2, {which is now 83mm} in .5 of a second. Moving it at 83m/s. {83mm per second} This is basically going at a constant speed, as its accelerated to moving at 83m/s.

So are you saying that I could have different accelerations and decelerations ? This is as I thought, but D. {douglis} seems to think other. {that is right is it not D. ?}


sophiecentaur said:
Force=Mass X Acceleration
(Then add the weight, in this case)

Misunderstand that a little, so best say and ask.

sophiecentaur said:
Are you assuming constant force all the time?

Hmm, with a muscle it would not be a constant force, but let’s says it’s a machine moving the weights and the force is constant.

Wayne
 
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  • #93
douglis said:
Again that question.Define the value of force you're interested in.The peak...the average or the "total" force(integration of force in respect of time)?

Impulse force, total, overall, integration of force in respect of time.

douglis said:
For the peak force...we need more data.

Enough now for 1 and 3, as 2 will not be much higher than the weight.

douglis said:
For the average force...in both cases you start and end at rest.The net change in momentum is therefore zero,

How do you work out the net change in momentum/movement is zero ? As the net force in 1 = 500mm and in 2 = 166mm. So the net, total momentum/movement will be 500 and 83 ?

I start at rest and end in rest, but the distance move on 1 = 500mm and 2 = 83mm

douglis said:
which is equal to the net impulse delivered. Therefore, the average force is equal with the weight in both cases...80 pounds or 356N.

For the "total" force...again in both cases is equal with gravity's impulse for .5sec.So...356 X .5=153N*s.

See, I don’t get how you come to this, as the below, shows the total or overall force to be higher for the faster moving in less time ? And its not the peak. Please see the video stating that more overall, total force was used with the fast rep, but this time the more force was used in "less" time, go from 5 min.



Fast
P = 695
F = 579Newtons
V = 192

Slow
P = 649
F = 546Newtons
V = 161

Wayne
 
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  • #94
sophiecentaur said:
Calculate the peak force needed to throw a computer out of a window in sheer exasperation!

WaynesWorldphysics ?

Please sophiecentaur, could you work out what the Newont force is below is, peak, average or total ?

Go from 5 min.



Fast
P = 695
F = 579Newtons
V = 192

Slow
P = 649
F = 546Newtons
V = 161

This one may help.

http://www.youtube.com/watch?v=Ycu6y4EHfog&feature=related

Wayne
 
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  • #95
sophiecentaur said:
So that is your definition of 'Integration'? It is not the Mathematical definition that is used (and works) in Physics so there is no point in your using the term.

I will write to an EMG expert, and ask then on intergration and RMS.

I will also write to the makers of my machine, and ask them what actualy my machine reads out on the average.

Wayne
 
  • #96
D. I just thought of somthing, I can video the machine and prove its NOT the peak force, but the average. Or you should be able to work it out here.

Take a look at the slow rep video, you will notice the peak force = ? was it a 190 somthing ? BUT the average was a 140 !

http://www.youtube.com/user/waynerock999?feature=guide#p/u/36/B8gtpp8ozvU

What do you say to that my friend D. ?

Wayne
 
  • #97
sophiecentaur said:
How can the machine distinguish between situations where there are and there aren't antagonistic muscles at work?

If I am curling, arm flexion, then I will but the four pads on my biceps, as these are the prime moves.

sophiecentaur said:
Are you saying that your machine 'knows' when your arm is moving and when it's stationary? Does it know then you are holding, lifting and lowering the weights?

Yes the machine know when my arm is moving and when it's stationary, holding, lifting and lowering the weights. As the pads detect “all/every” of the electrical signals in my muscles the pads are on.

Here take a look at the makers video, go to 1.40min



Or I could make a video if you want.

So if they say the fast as a higher average, as a Physicist, thought you would be very interested, that is, if you do agree with D ? But to me he has not added in all the variables, like ground reaction muscle force and so forth, and left out Kinology and Biomechanics.

sophiecentaur said:
How can you expect to get a proper answer whilst you still insist on using the term force/strength? Do me a favour and look the individual words up. They describe entirely different aspects of Physics. Which one do you mean when you use that term? Why do you hang on to these deliberately nonsense terms instead of using the right one? You are saying black is white on every occasion.

Ok sorry, I will try the stick with force.

sophiecentaur said:
The very least you could do, if you really do want some sense, is to use the correct terms. Imagine you had a calculator and the + key sometimes gave you a - and the X key sometimes gave you a ÷. You would say it was rubbish, wouldn't you? Constantly using confusing terms is the equivalent to a dodgy calculator.

Ok get your point.

sophiecentaur said:
At least, you could do us all the courtesy of talking the right language. (The language that 11 year old kids are quite happy to learn to use in School.) Don't ask me to help you with this - just look up any word you want to use and see if it actually fits what you want to say. I get the impression that you are not looking anywhere else for your information but just want to be spoon fed by PF. This is unreasonable.

btw, I don't have to justify the Physics Equations in this context. They work fine for everyone but you so I am not out of step here. Give me a proper question (not ten pages of weight lifting jargon) and I can guarantee a good answer. Give me another 'Wayne' question and there will be no available answer from Physics.

Ok, I will try and use physics, if I can't will ask.

Wayne
 
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  • #98
waynexk8 said:
WaynesWorldphysics ?

Please sophiecentaur, could you work out what the Newont force is below is, peak, average or total ?

1. If you can't tell me the acceleration (i.e. what is the variation of velocity with time during the lift? There are infinite possible combinations that will get the weight from bottom to top of the lift in a given time.) I cannot tell you the force. (Did you not read my F=mA formula?)

2. Because the weight starts and ends stationary, the Mean additional force must be zero and the mean force will be the weight.. (I think this had been pointed out several times already.)

3. What does "total force" mean? Do we add up the forces, measured every second, every tenth of a second, every 100th of a second? It's a nonsense concept as you can only validly add forces that operate at the same time.. Ask the makers of your machine for an answer. There is not a PF answer for you.

It matters not whether you are working in Imperial or Metric - all three questions are either nonsense of indeterminable.
 
  • #99
Big thank you for staying with me.

sophiecentaur said:
1. If you can't tell me the acceleration (i.e. what is the variation of velocity with time during the lift? There are infinite possible combinations that will get the weight from bottom to top of the lift in a given time.) I cannot tell you the force. (Did you not read my F=mA formula?)

Hmm, I thought I told you this on my other post ? Ok, this is where your help will have to come in, as I am not sure how to work this out. Can we call it for now a constant acceleration ? If so, on 1, the weight accelerates from rest to 400mm in 0.4 of a second, then decelerates the last 100mm in .1 of a second

sophiecentaur said:
2. Because the weight starts and ends stationary, the Mean additional force must be zero and the mean force will be the weight.. (I think this had been pointed out several times already.)

So as I push up with the force of the weight to move the weight, and then the weight cancels that force out, then you call the mean additional force {that my muscles creating force} must be zero ? If I am right, sort of get that, however, I have used forces, from a 100 to 1 pounds, and that’s all we are concerned about ? Or am I missing something.

My other point is, that I don’t think that when I am using far higher forces, like 100 pounds for the accelerations, that when I am then using slightly less force than 80 pounds for the decelerations, that when the slow rep is roughly using a constant 80 pounds, that the slow reps medium forces can NOT make up or balance out the very high force {the very high tensions that the very high forces have put on the muscles, as of the action reaction force thus tensions on the muscles} that the fast reps are putting out, that’s why the fast reps have used more energy and moved the weight 6 times further in my opinion.

Not sure you get what I say there, please say if you don’t, it’s like a person hits you with great force, and it hits you down, but it would take far more lower force hits and more “time” {but in this debate the time is the same} to hit you down with lower force hits. THIS is why you always fail at lifting the weight, or you hit momentary muscular failure faster with the faster reps, as they ARE doing more damage with the higher forces.

I am not saying the physics equations are wrong, it’s just they cannot tell the full story, as all the variables as liker the high force to medium force has not been worked out, that’s why the ENG states more average force used in the faster reps.

sophiecentaur said:
3. What does "total force" mean? Do we add up the forces, measured every second, every tenth of a second, every 100th of a second? It's a nonsense concept as you can only validly add forces that operate at the same time.. Ask the makers of your machine for an answer. There is not a PF answer for you.

It matters not whether you are working in Imperial or Metric - all three questions are either nonsense of indeterminable.

What I mean with total or overall force, is that if you lift say 80% of your 1RM, you can only lift it for a certain amount of times in a time frame at a certain speed. Let’s say you could lift it up and down 10 times at 1 second up and 1 second down, then at 20 seconds you could not lift it again, so you had in your muscles 20 seconds or 10 lifts in you at that rep speed, of force, after that your force was temporary no longer. Yes I know that sounds a bit daft, but that is actually what happens, and if you had lifted the same weight up and down in .5 of a second up and .5 of a second up, you would have most probably failed to lift the weight in 10 to 12 seconds. Meaning you have used up your temporary force up far faster.

So let’s “just” {please this is just an example to get my point over} say for an example you had 1000 forces to lift the weight, in the fast, you used up this force far far far faster, meaning if you both lift the weight for a set time, and do “not” lift until momentary muscular failure, the faster reps “must” be using up more force faster, as you fail faster lifting faster. Example of how the fast are using more force and faster, more energy used, more distance the weight has been moved, faster to muscular failure, the EMG states more muscle activity or muscle force. I know all the above sounds a bit complicated, but there is total since in there.

Thank you again for you time and help, not sure about the acceleration, hope to learn more on that.

Wayne
 
  • #100
waynexk8 said:
Big thank you for staying with me.

Hmm, I thought I told you this on my other post ? Ok, this is where your help will have to come in, as I am not sure how to work this out. Can we call it for now a constant acceleration ? If so, on 1, the weight accelerates from rest to 400mm in 0.4 of a second, then decelerates the last 100mm in .1 of a second

O.K. I'll try to help you understand once again.
Let's say in your above example the load is 800N(81.5kg) while your maximum force ability is 1000N.

For the first 0.4sec you're applying your Fmax (although in reality that's biomechanically impossible) so the net force is 1000-800=200N.
So your acceleration for those 0.4sec is a=F/m=200/81.5=2.45m/s^2

For the last 0.1sec you let the gravity decelerate the load so the net force is -800N
So your acceleration for those 0.1sec is a=F/m=-800/81.5=-9.81m/s^2 and obviously it's equal with g.

So as I push up with the force of the weight to move the weight, and then the weight cancels that force out, then you call the mean additional force {that my muscles creating force} must be zero ? If I am right, sort of get that, however, I have used forces, from a 100 to 1 pounds, and that’s all we are concerned about ? Or am I missing something.

My other point is, that I don’t think that when I am using far higher forces, like 100 pounds for the accelerations, that when I am then using slightly less force than 80 pounds for the decelerations, that when the slow rep is roughly using a constant 80 pounds, that the slow reps medium forces can NOT make up or balance out the very high force {the very high tensions that the very high forces have put on the muscles, as of the action reaction force thus tensions on the muscles} that the fast reps are putting out, that’s why the fast reps have used more energy and moved the weight 6 times further in my opinion.

As I proved you above you used positive acceleration equal with 2.45m/s^2 for the 80% and 4 times greater negative acceleration equal with -9.81m/s^2 for the last 20%.
That's why we're telling you the acceleration is offset by the deceleration.The average acceleration is always zero.
In the equation of force F=mg+ma the "ma" part is always zero so F=mg or else the force is equal with the weight.No Mean additonal force is required.The forces "make up","balance out" or call it whatever you like.

I don't believe it's possible to get a more simple explanation.

I am not saying the physics equations are wrong, it’s just they cannot tell the full story, as all the variables as liker the high force to medium force has not been worked out, that’s why the EMG states more average force used in the faster reps.

No...your EMG states that greater RMS is used in faster reps...not average force.

What I mean with total or overall force, is that if you lift say 80% of your 1RM, you can only lift it for a certain amount of times in a time frame at a certain speed. Let’s say you could lift it up and down 10 times at 1 second up and 1 second down, then at 20 seconds you could not lift it again, so you had in your muscles 20 seconds or 10 lifts in you at that rep speed, of force, after that your force was temporary no longer. Yes I know that sounds a bit daft, but that is actually what happens, and if you had lifted the same weight up and down in .5 of a second up and .5 of a second up, you would have most probably failed to lift the weight in 10 to 12 seconds. Meaning you have used up your temporary force up far faster.

Wayne

This is the last time I bother to even read that particular question.

You "fail" in a weight lifting set when you have no longer enough energy to apply force equal with the weight.
"Failing" faster with a certain kind of lifting means that with this kind of lifting you spend energy at a higher rate...NOT that you use more force.In all cases the average force is equal with the weight.
It's the fluctuations of force that are more energy demanding.That's the only scientific answer you can get.
 
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