Wayne,
Let me clarify my question. Under which condition do you feel would produce the greatest amount of muscular force; 1) Someone who is lifting their 1 RM which is performed at a slow speed, or 2) Someone who is lifting 50% of their 1 RM at a very fast speed?
The problem that you are having regarding the physicist vs. physiologist scenario is that from a physiological standpoint your muscles are simply unable to lift heavy weights quickly. This is because as you increase the speed of the contraction the total number of actin-myosin cross-bridges that are formed at any given point in time are reduced. This needs to happen to allow the muscle to move at a faster velocity. It is only when these actin-myosin cross-bridges are formed that muscular force can be produced (please see my earlier "tug of war" example regarding that force can only be generated on the rope when the feet are in contact with the ground). This is the reason why you are able to hold a weight that is greater than your 1RM statically for a short period of time. This also explains why when you perform a 1 RM why the weight is moved slowly. To handle a weight close to your max you must maximize the total number of cross-bridges that are formed which occurs at a slow velocity. This is also the reason why when you move a weight quickly that less force is produced. The body is not a machine that is capable of producing endless amounts of forces at the velocities you provided in the examples above. These are the principles that your physicist must be aware of. He needs to understand how the body actually works in addition to the math.
In regards to your EMG data, others have provided you a clear rationale as to why your data analysis might be flawed. I am not going to pretend to know exactly how to interpret EMG data analysis, but I do understand basic muscle physiology. The EMG is not a direct measurement of muscular force, but rather the electrical activity associated with the muscle during movement. This could be increased through two different ways; 1) increased force of contraction & 2) increased velocity of the contraction. Your data analysis is focused exclusively on the first aspect while completely neglecting the second. As an example I will provide information from an ECG interpretation of the heart, which utilizes the same principles. An increase in ECG activity can be observed if 1) you were to increase the strength of each heart contraction or 2) if you were to increase your heart rate. I could very easily increase my heart rate without increasing the force of the heart contraction. If I were to solely look at ECG activity it would be increased, but this increase would have nothing to do with the force of each heart contraction.
In the observation I asked you to set up I was trying to test out this theory in regards to your EMG data. I wanted to set up a situation based on physiological principles where the amount of muscular force produced during the fast contraction speed have to be lower than the amount of muscular force produced during a 1RM. I also set up this experiment as a way of maximizing muscular power (which is a completely separate variable). If your EMG data is higher during the fast contraction with a weight that is 50% of your 1 RM compared to the slow contraction performed at your 1 RM your data analysis would be flawed in regards to the faster contraction being capable of producing more force. Instead, what I am suspecting that you are measuring is an increase in muscular power and the higher EMG signal is being caused by an increased rate of cross-bridge cycling due to the faster velocity (see heart rate in the above EKG example).
Let me ask you for the final time. Have you performed this simple observation yet and what are your results? If you don't understand the premise of the experiment and your answer to my initial question in this post is that the person who is lifting 50% of their 1 RM at a fast velocity would be capable of producing more force then your problem is that you simply don't understand physiology as this is not what is observed in reality as shown by the force-velocity curve.
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11-28-2011, 10:41 AM #121
Last edited by SumDumGoi; 11-28-2011 at 10:47 AM.
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11-29-2011, 04:09 PM #122
Yes, BUT how do you think that the median forces make up or balance out the faster peak forces ??? Yes I know the fast has a deceleration, but still how can 100% force for say 60% of the ROM, then this forces goes slowly down from 100 to zero {like the slow rep has to as well} be made up or balanced out by the faster reps, lets recap, there is one slow up at 3/3 and 6 fast reps at .5/.5
ANOTHER THING TWO THINGS WANT TO CLEAR UP, we did go over this before, but could we clear this up for once and for all. These numbers are just for this, so don’t take them as 100% fact. We break the fast concentric up into 15 parts of force, and if D. {bet he’s even got a Christmas present for me this year ROL} is right on deceleration it goes like this, as in a person using 80% {80 pounds} and the rep taking 1.5 seconds, the study says they decelerate at 60% of the ROM.
60% is on part 9.
100 100 100 100 95 90 85 80 75 70 65 60 30 10 zero on transition and reverse for the eccentric.
What about this.
100 100 100 100 100 100 100 100 90 80 70 50 40 20 zero on transition and reverse for the eccentric.
As does deceleration in EVERY case, mean you are then using less force than the weight, in this case 79 pounds, or can it mean you are not accelerating so fast, thus decelerating, so using less and less force as in 2.
Slow would be more like this.
80 80 80 80 80 80 80 80 80 80 80 70 60 40 zero
No need for an explanation, just say 2 can happen or it can’t. However to be honest I always would have thought 2 would have been deceleration, but I never thought about it or read about it before.
So next, the above on the deceleration at 60% was taken from a study that used 80% but the concentric rep took 1.5 seconds, what would happen to the deceleration if the rep took 3 seconds, and what would happen if it took .5 of a second, opinions and facts please. AND WITH THE SLOW REP, HOW DO WE NOT KNOW THIS REP IS DECELERATING FOR 40% OF THE REP AS WELL ???
Thx for all the help and time
Wayne
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11-29-2011, 05:25 PM #123
Your peak force is still not going to be higher during a faster rep compared to a slower rep. You lack a fundamental understanding of basic physiology and are therefore confused about the issue. But feel free to continue on with make believe numbers while never once attempting to perform the basic experiment I asked you to perform which demonstrates the point I made in my previous sentence.
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11-29-2011, 08:08 PM #124
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11-30-2011, 01:08 AM #125
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11-30-2011, 11:31 AM #126
Going out, internet seems ok, will get back to all tomorrow.
Hi all, just done the experiment, these were static holds with my EMG machine pads on my biceps and forearm. For those new into this thread, an EMG reads the muscle or in this case the average muscle activity for a certain time frame.
I was as I would have thought, not sure what other here was thinking, and looking forward to what this proves, me right in part of this EMG debate or me wrong. The machine times itself, and every time I had the weight in the midway point before I pressed the button.
First best say just in case people here do not know. You can lower more under control than you can lift. So if my repetition maximum was 100 pounds, I could lower say 130 to 140 pounds under control. This is because the muscle fibers are more efficient at lowering, {not 100% this is right} as think of a fish and its scales, you can slide you hand over the smooth fish, but try going backwards and it’s not the same story. Also the fast muscle fibers, the ones that are used for the repetition maximums, or the heaver lifting compeered to the slow muscles that are called upon for endurance work, well the lower calls upon these fast muscle fibers more efficiently.
Static holds, with weight getting 10 pound heaver every time, starting at 30.
1,
67.6
2,
105.6
3,
148.7
Then I did a slow and then fast with the last weight, on the fast I was still able to rep, but not full reps, meaning it was getting very hard.
4,
228.1
5,
257.
Wayne
From someone over at the physics forum.
Hmm, well, I believe part of it is that they like to keep this pretty textbook and educational, without a lot of stuff that would confuse students that came here, in my opinion.
If you could please do a few more EMG tests for me to get an idea of what is going on,
Please do a test where you hold your empty hand at that same height(grip your hand as tightly as you would grip the bar, if you can) and also do a slow and fast test with no weight.
This thread has made me realize that if we considered it to be two constant forces(i.e. if you pushed with a constant force, and gravity is the other) Then you should be able to determine the force applied, but it is also a simplification of what is happening, and doesn't directly represent what happens when one lifts weights.
I figure that since as was mentioned many times the impulse must be equal and opposite to have a 0 velocity on both ends, that means that
gT = Ft1
where g is the force of gravity, T is the overall time, F is the force you pushed with and t1 is how long you pushed for
The work done must also be the same so
gX = Fx1
where g is gravity again, X is the overall distance, F is the force applied, and x1 is the distance that it was applied
since f = ma we know that we can get the acceleration from the force, and so it must also be true that
x1 = .5(a)t12
where a = (F-g)/m because we need the net force during the time that we are pushing and gravity is pushing back. You can combine those equations and solve for
F = g2t2/(gt2-2xm)
So this gives you the constant force required to move an object against gravity for a distance of x in a time of t with a mass of mHmm, well, I believe part of it is that they like to keep this pretty textbook and educational, without a lot of stuff that would confuse students that came here, in my opinion.
If you could please do a few more EMG tests for me to get an idea of what is going on,
Please do a test where you hold your empty hand at that same height(grip your hand as tightly as you would grip the bar, if you can) and also do a slow and fast test with no weight.
This thread has made me realize that if we considered it to be two constant forces(i.e. if you pushed with a constant force, and gravity is the other) Then you should be able to determine the force applied, but it is also a simplification of what is happening, and doesn't directly represent what happens when one lifts weights.
I figure that since as was mentioned many times the impulse must be equal and opposite to have a 0 velocity on both ends, that means that
gT = Ft1
where g is the force of gravity, T is the overall time, F is the force you pushed with and t1 is how long you pushed for
The work done must also be the same so
gX = Fx1
where g is gravity again, X is the overall distance, F is the force applied, and x1 is the distance that it was applied
since f = ma we know that we can get the acceleration from the force, and so it must also be true that
x1 = .5(a)t12
where a = (F-g)/m because we need the net force during the time that we are pushing and gravity is pushing back. You can combine those equations and solve for
F = g2t2/(gt2-2xm)
So this gives you the constant force required to move an object against gravity for a distance of x in a time of t with a mass of m.
This would be a good time to reemphasize that this is a simplification, and doesn't directly represent what happens when one lifts weights. When one actually lifts weights I am sure the force applied varies greatly over time, and is NOT constant. This equation gives you what the force would be from a machine that supplied a constant acceleration and then stops instantly at t1
What you are saying is that a greater average speed(in terms of overall distace/overall time) must have had a greater force, and that does make sense
because gravity will slow the object down at 9.8m/s2 no matter the velocity it gets, so to go further in a short time it must build up velocity quickly
Running the data you gave me through that equation gives:
F = g2t2/(gt2-2xm)
A) 80lbs(36kg) is 352.8N for 1m in .5s
F = (352.82 * .52) / [( 352.8*.52) - 2 * 36 * 1]
F = (124467.84 * .25 ) / (88.2 - 72)
F = 31116.96 / 16.2
F = 1920.8N
B) 80lbs(36kg) is 352.8N for .166M in .5s * note all that changes is x
F = (352.82 * .52) / [( 352.8*.52) - 2 * 36 * .166]
F = 31116.96 / 79.848
F = 389.7N
But here is why we say that over the same time the force is the same:
gT = Ft1
F = ma
A) 352.8N(g) * .5s(T) = 1920.8(F) * t1
176.4 = 1920.8t1
t1 = .092s
So the greater force (1920.8) was only applied for .092 of the .5s that is 18.4% of the time.
B) 352.8N * .5 = 389.7N * t1
176.4 = 389.7t1
t1 = .45s
So the lesser force was applied for .45s that is 90% of the time
Maybe this will help though.
Wayne
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11-30-2011, 02:31 PM #127
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12-01-2011, 02:31 PM #128
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12-01-2011, 02:33 PM #129
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12-01-2011, 02:38 PM #130
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12-01-2011, 03:56 PM #131
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No Wayne. We all agree that peak force is LOWER the faster the bar speed, well everyone but you.
pounds of force 400 @ 1000 rpm = 76 horsepower
pounds of force 350 @ 2000 rpm = 133 horsepower
pounds of force 300 @ 3000 rpm = 171 horsepower
pounds of force 250 @ 4000 rpm = 190 horsepower
pounds of force 200 @ 5000 rpm = 210 horsepower
Force is dropping, horsepower is increasing as rpm increases. The human body does the exact same thing.
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12-01-2011, 05:02 PM #132
But this slow speed, will be as fast as the person can move the weight, and that’s what this debate is about.
The greatest force and time would be the 1RM.
But this is not the debate at all ???
Speed here is a relative word. Actually as I said, on heaver weight the muscles are trying to lift them as fast as possible.
This has basically nothing to do with the debate, think you may have the debate back to front, sorry there, could be part my fault, bet D. has had it wrong as well.
Sorry have not read all the posts yet, but most should know that an EMG takes the muscle activity, I mean what more do you want, as more activity more force/strength used right ??? I mean all have seen EMG test on bench press, incline bench press and decline bench press, which shows which has the most pec activity.
Right.
But to increase velocity, YOU MUST HAVE MORE FORCE/STRENGTH used.
No its not, force and velocity are sort of related, you can’t have one without the other. More force more velocity, more velocity more force, how can you have it another way ??? To change a body's velocity there must be a net force acting on that body. A car will decelerate when you take your foot off the pedal, because there will be forces acting to decelerate it, and when you hit the pedal again, the car accelerates with its opposing forces. Force has no direct relationship with velocity, only acceleration.
This is taken from a site;
The way I visualize it is to imagine a force acting on a particle for a particular amount of time--say 1 second.
The work done on the particle is Force × the distance it moved.
Power is work/time, so that is:
P = (force × distance) / time
But that's the same as:
P = force × (distance / time)
And since (distance / time) = speed,
P = force × speed
D. seems to this more power = more force is not true, but he can NOT explain why.
__________________
How could you increase your heart rate without increasing the force of the heart contraction ???
It’s not measuring power, its measuring muscle activity, force/strength.
Here are a few tests I did, two pads on biceps and two pads on foramens.
Held out 15 pounds in the middle of a concentration curl, then added 10 pounds and then another 10 pounds.
67.6
148.7
228
Held out arm only in the middle of a concentration curl. Held a 3.5 pound DB bar out only in the middle of a concentration curl. Did reps as fast as possible with the 3.5 pound DB bar.
8.5
17.2
123
Will do your test, but it will show the 1RM higher. But this is not the debate, as the weight is different and the time is different.
Wayne
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12-01-2011, 05:36 PM #133Zula wrote;
If you could please do a few more EMG tests for me to get an idea of what is going on,
Please do a test where you hold your empty hand at that same height(grip your hand as tightly as you would grip the bar, if you can) and also do a slow and fast test with no weight.
Sorry, on the first test the weight was 15 pound to start not 30.
Here are a few tests I did, two pads on biceps and two pads on foramens.
Held out 15 pounds in the middle of a concentration curl, then added 10 pounds and then another 10 pounds.
67.6
148.7
228
Held out arm only in the middle of a concentration curl. Held a 3.5 pound DB bar out only in the middle of a concentration curl. Did reps as fast as possible with the 3.5 pound DB bar. Just held my hand out, and lightly griped. Did a slow curls with no weight. Did fast curls with no weight.
8.5
17.2
123
15.2
16.5
80.7
Zula wrote;This thread has made me realize that if we considered it to be two constant forces(i.e. if you pushed with a constant force, and gravity is the other) Then you should be able to determine the force applied, but it is also a simplification of what is happening, and doesn't directly represent what happens when one lifts weights.
Yes my force/strength pushing a weight and gravity pushing back, and the harder you push the more resistance there will be.
Zula wrote;I figure that since as was mentioned many times the impulse must be equal and opposite to have a 0 velocity on both ends, that means that
gT = Ft1
where g is the force of gravity, T is the overall time, F is the force you pushed with and t1 is how long you pushed for
The work done must also be the same so
gX = Fx1
where g is gravity again, X is the overall distance, F is the force applied, and x1 is the distance that it was applied
since f = ma we know that we can get the acceleration from the force, and so it must also be true that
x1 = .5(a)t12
where a = (F-g)/m because we need the net force during the time that we are pushing and gravity is pushing back. You can combine those equations and solve for
F = g2t2/(gt2-2xm)
So this gives you the constant force required to move an object against gravity for a distance of x in a time of t with a mass of m
This would be a good time to reemphasize that this is a simplification, and doesn't directly represent what happens when one lifts weights. When one actually lifts weights I am sure the force applied varies greatly over time, and is NOT constant.
Yes there will be many different forces thought the rep, as of the biomechanical advantages and disadvantages. However, I don’t mind working it out on a machine lifting the weights, as it’s the same, the faster you lift the more the opposing force, thus more and more force will be needed the faster you go, also the faster you go the more distance you will move the weight in the same time frame, and to move a weight further in the same time frame needs more force.
Zula wrote;This equation gives you what the force would be from a machine that supplied a constant acceleration and then stops instantly at t1
What you are saying is that a greater average speed(in terms of overall distace/overall time) must have had a greater force, and that does make sense
because gravity will slow the object down at 9.8m/s2 no matter the velocity it gets, so to go further in a short time it must build up velocity quickly
Running the data you gave me through that equation gives:
F = g2t2/(gt2-2xm)
A) 80lbs(36kg) is 352.8N for 1m in .5s
F = (352.82 * .52) / [( 352.8*.52) - 2 * 36 * 1]
F = (124467.84 * .25 ) / (88.2 - 72)
F = 31116.96 / 16.2
F = 1920.8N
B) 80lbs(36kg) is 352.8N for .166M in .5s * note all that changes is x
F = (352.82 * .52) / [( 352.8*.52) - 2 * 36 * .166]
F = 31116.96 / 79.848
F = 389.7N
But here is why we say that over the same time the force is the same:
gT = Ft1
F = ma
A) 352.8N(g) * .5s(T) = 1920.8(F) * t1
176.4 = 1920.8t1
t1 = .092s
So the greater force (1920.8) was only applied for .092 of the .5s that is 18.4% of the time.
B) 352.8N * .5 = 389.7N * t1
176.4 = 389.7t1
t1 = .45s
So the lesser force was applied for .45s that is 90% of the time
Maybe this will help though
Sorry I don’t get why the two are different ??? ANYONE HERE PLEAE.
Originally Posted by Zula110100100
Hmm, sorry I still don’t get it, still don’t get why you say that over the same time the force is the same, As I don’t understand the two physics equation, don’t understand why or how you worked out two different equations for the same lifts, could you please try and tell me why they worked out different in more layman’s terms ??? Also still not sure why you say that the fast greater force (1920.8) was only applied for .092 of the .5s that is 18.4% of the time, Am I not Appling, {that’s if it’s a machine moving the weight} 1920.8 for just about the whole 60% of the rep ??? And if it’s the second rep, the forces must be bigger as of the higher peak forces.
Put this over at BB.com, would you like to join and post over there, or carry on like this if you like and I will post these over there, as there a lot very clever people over there.
Wayne
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12-01-2011, 05:57 PM #134
NO NO NO, WHAT ARE YOU TWO ON ABOUT NOW, WE ALL AGRRED FROM THE FIRST SECOND OF THE DEBATE THE FAST REP CREATS MORE PECK FORCE.
What you some of you people on about ??? Think you got the debate the wrong way round, sorry that could be part on me, but don’t see how. I am not talking about the force/velocity curve for the last time, I am not on about that you can generate more force on a very heavy weight than a light one, I know and agree with all that, that has nothing to do with this debate.
We lift the same weight, let’s say 80% for 1m up, I lift the weight fast as I can, this will create the highest force possible, I mean just jump on a scales lift the weight slow, then lift it as fast as possible, you will then see the reading go up by a long way, as when you push up the is an opposite reaction. The Newton is the SI unit for force; it is equal to the amount of net force required to accelerate a mass of one kilogram at a rate of one meter per second squared. In dimensional analysis, F = ma, multiplying m (kg) by a (m/s2), SO THE MORE NEWTON FORCE YOU USE ON THE SAME OBJECT THAT’S THE SAME WEIGHT, YOU HAVE MORE ACCELERATION AND VELOCITY, AND MORE PEAK FORCE, AND MUCH MORE PEAK FORCE ON THE TRANSITION FROM NEGATIVE TO POSITIVE.
F = ma lets us work out the forces at work on objects by multiplying the mass of the object by the acceleration of the object.
Example:
The force at work on a Formula 1 car as it starts a race! If the F1 car has a Mass of 600kg and an Acceleration of 20m/s/s then we can work out the Force pushing the car by multiplying the Mass by the Acceleration like this 600 x 20 = 12000N. SO IF IT MOVES FASTER LIKE 40M/S/S ITS 600 X 40 = 24000N.
A force however will produce acceleration, according to Newton's Second Law: F=ma, or force = mass x acceleration. Newton's Second law of motion states that the net force on an object is directly proportional to its rate of change of momentum. Thus F= m(v-u)/t where F = Force, M = mass, v = final speed, u = initial speed and t is the change in time. This is because a change in momentum is m(v-u). (v-u)/t is the rate of change of velocity which is acceleration. Thus, F=ma. Acceleration = Force / Mass.
Wayne
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12-02-2011, 10:32 AM #135
Let’s see you try and prove this, with basic numbers
40 + 40 x 0 + 1 = ???
Is not 40 + 40 = 80 ??? Now we x 80 by 0, and whatever we x 0 by it will always be 0 right ??? So we are now at 0 right ??? So add 1 to 0 = 1 right ???
Wayne
D. wrote;
Instead of trying to prove nonsense learn to do the mathematic acts at the right order or find a kid to show you.
D. YOU CAN NOT CHANGE THE QUESTION NOR THE ORDER OF THE QUESTION, WHY DO YOU DO THIS ??? HAVE YOU BEEN DOING THIS IN THIS DEBATE TOO SUIT THE ANSWER YOU WANT. PLEASE TELL ME WHY YOU CHANGED MY QUESTION AROUND, THAT JUST CANT BE DONE, AS I ASK THE QUESTION, YOU CAN NOT CHANGE IT
LOOK, you CANT change the order of the question to suit you, WHY, and when I say WHY, I mean please give me an answer as why you THINK you can change the order of the question ??? IF you change the order of the QUESTION, it NO longer because the same question, thus you CAN NOT changed the dammed order of the question, I can’t believe anyone can THINK they can answer a question like this, with changing the order of the question.
He is what happens when you change questions, ONE, YOU HAVE NOT ANSWERED THE ORIGINAL QUESTION, HAVE YOU ??? YES OR NO ???
TWO, I ask you this question, 4 + 4 = 8 x that number by 2 = 32, YOU might think I am wrong, but ho not, well I am not, well I am but I am now doing what you did, {and what you’re doing in our big physics debate} I changed the question to suit myself, I changed it to this, 4 x 4 = 16 x that number by 2 = 32.
I cannot believe anyone could try and change the question, have you a good explanation for this ???
Wayne
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12-02-2011, 10:47 AM #136
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12-02-2011, 10:56 AM #137
Yes you can measure the above.
Right.
All depends on the amount of time you do both lifts.
The high velocity/low weight, it would only be higher force if it was dome for a longer time span. But in my debate we are talking of the same time span, so if it took 4 seconds to do your 1RM, then you would have to do the other reps for 4 seconds, but then the weight is different, and that’s not the debate.
Yes, what you say was good, and I thank you.
Wayne
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12-02-2011, 11:01 AM #138
EMG does NOT measure the CNS.
Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. thus more activity more force, just like I told you years ago.
http://en.wikipedia.org/wiki/Electromyography
Wayne
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12-02-2011, 11:02 AM #139
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12-02-2011, 11:05 AM #140
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12-02-2011, 11:09 AM #141
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12-02-2011, 11:10 AM #142
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12-02-2011, 11:12 AM #143
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12-02-2011, 11:15 AM #144
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12-02-2011, 11:16 AM #145
Well an EMG signal will not necessarily reflect the total amount of force (or torque) a muscle can generate. The number of motor units recorded by electrodes will be less than the total number of motor units that are firing.
Electrodes can't pick up all motor units.
So, if a newly recruited motor unit is close to the electrode the relative increase in the EMG signal amp will be greater than the corresponding increase in force. Likewise I'm sure if a motor unit is too far from the elctrode the ampl will not change but the force will increase.
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12-02-2011, 11:17 AM #146
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12-02-2011, 11:18 AM #147
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12-02-2011, 11:19 AM #148
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12-02-2011, 11:22 AM #149
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12-02-2011, 11:26 AM #150
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