Thread: Discussion on Muscle Friction

Originally Posted by Duncans Donuts

Any thoughts?

Ive got none.

Originally Posted by du510

Ive got none.

Quick, where's the 'surprised' icon...

Muscle friction causes you to lift heavier than you think your lifting. If you lift a 55 pound dumbbell muscle friction may be causing you to lift 55 pounds. But friction will make lowering the weight easier. With the same dumbbell you may be lowering 45 pounds. Muscle friction may also be partailly responsable for muscle soreness. That's what I was told, but I'm not sure if that has all been proven.

Originally Posted by ihateschoolmt

Muscle friction may also be partailly responsable for muscle soreness. That's what I was told, but I'm not sure if that has all been proven.

I remember reading something like that. I believe muscle friction is somewhat responsible for soreness, among other things.

As far as lifting speed goes, fast lifting creates momentum and doesn't promote blood flow to the muscle. Slow movement creates less momentum and less internal muscle friction. Slow lifting also requires a more even application of muscle power throughout the movement range which promotes rapid blood flow into the specific muscle you're training. To sum it up, the concentric, or positive phase of a lift should be performed faster than the eccentric (negative) phase. 1-2 seconds positive, 4-5 seconds negative.

Originally Posted by Duncans Donuts

concentric and eccentric exercise.

I know this is a stupid question, but what does that mean? I've never heard it and the definition in the dictionary doesn't make sence.

Originally Posted by ihateschoolmt

I know this is a stupid question, but what does that mean? I've never heard it and the definition in the dictionary doesn't make sence.

Concentric is the positive phase of a lift in which the targeted muscle is actually doing the work. Eccentric is the negative phase where you are returning the weight back to its starting position(resistance).

Correct me if I'm wrong...

Originally Posted by reg56

Concentric is the positive phase of a lift in which the targeted muscle is actually doing the work. Eccentric is the negative phase where you are returning the weight back to its starting position(resistance).

Correct me if I'm wrong...

Wow, the dictionary definition wasn't even close. It said something about a center point.

o sum it up, the concentric, or positive phase of a lift should be performed faster than the eccentric (negative) phase. 1-2 seconds positive, 4-5 seconds negative.

I usually don't dictate the speed of my concentric rather just think explosive. But that is a good way to do it......explosive concentric followed by a slower eccentric.

Concentric is positive, eccentric is negative

The board needs more threads like this. I usually have to search for advanced things like this.

Concentric is where the muscle contracts under tensions. Eccentric is where the muscle stretches under tension.

What is muscle friction anyway?

Friction against other muscles? or against bone? what?

Friction is a "force that resists the relative motion or tendency to such motion of two bodies in contact". Muscles by nature (contracting and stretching) generate friction within themselves.

So the individual fibres create friction against one another?Why would that be? Is it because some fibres are contracting/stretching at a different rate to others?

Perhaps muscle friction has something to do with the hypertrophy induction effects that eccentric motion has on skeletal muscle. Perhaps there is more friction during the eccentric part, or something of the sort? Just some random speculation; I've never looked into the topic of muscle friction.

Simply put, muscle friction works against your favor during the concentric contraction, and for your favor during the eccentric contraction. This is why negative strength is greater than positive strength.

Think of it like this: assume a car is going uphill. At this point, the car must overcome the load as well as several points of friction, including the tires on the ground and air resistance. However, in wanting to control the descent as soon as the car overcomes the hill goes down, the friction works in your favor.

Think about it for a moment: how much force is required to lift 100 pounds of weight, at any constant speed of upwards movement? The answer? 100 pounds of force, no more and no less; because, if you exert more than 100 pounds of upwards force, then the speed of movement would not remain constant; instead, the speed of upwards movement would increase. So the fact that the upwards speed of movement remains constant is clear proof that the upwards force is exactly equal to the downwards force produced by gravity that is acting upon the weight.

This of course implies that, given a common cadence, the same amount of force used to move the load MUST EQUAL the amount of downward gravitational force imposed by the load. So why is the negative part so much easier? Look to the above example.

So the individual fibres create friction against one another?Why would that be?

Because everything that has motion and mass has friction..

Originally Posted by CowPimp

Perhaps there is more friction during the eccentric part, or something of the sort?

There is the same amount of friction in both, but it is helpful on eccentric and makes concentric harder. It would be like if you had to pull a 90 pound box up a 20 degree incline. Would you rather use a ramp with a textured surface, or a smooth surface? Of course you want the smooth surface. The friction made by the smooth surface might be 10 pounds, making you push up 100 pounds. The friction produced by a textured surface might be 20 pounds of friction, making you push up 110 pounds. BUT if you wanted to lower the box down a ramp, you would want the textured surface because the friction produced would be 20 pounds still, so you are lower a 70 pound box. So the friction produced would be the same lower and raising the something, it just works with you on the eccentric. Hope that makes since.

I understand the concept of friction very well. Friction is strictly an opposing force whose quantity is equal to the normal force multiploed by the coefficient of friction between the two rigid bodies.

I should've phrased my statement better. It came out wrong. My speculation was that friction durring eccentric movement is actually causing more microtrauma to the muscle.

I was just thinking that perhaps muscle friction has something to do with the fact that eccentric motion is more effective at inducing hypertrophy.

Originally Posted by CowPimp

I should've phrased my statement better. It came out wrong. My speculation was that friction durring eccentric movement is actually causing more microtrauma to the muscle.

I was just thinking that perhaps muscle friction has something to do with the fact that eccentric motion is more effective at inducing hypertrophy.

That's interesting, I've never heard that before. Any studies backing that up?

Originally Posted by ihateschoolmt

That's interesting, I've never heard that before. Any studies backing that up?

I've read this for years

Originally Posted by Cold Iron

I've read this for years

I'm still kind of new to working out.

This thread is very interesting. Does the amount of friction change, based on the amount of weight being lifted? Or is it a constant level of friction?

If someone relaxes their arm, you can easily move it. Would seem there is little to no friction during rest.

Originally Posted by SlimShady

This thread is very interesting. Does the amount of friction change, based on the amount of weight being lifted? Or is it a constant level of friction?

Friction is strictly an opposing force whose quantity is equal to the normal force multiplied by the coefficient of friction between the two rigid bodies.

Originally Posted by ihateschoolmt

Friction is strictly an opposing force whose quantity is equal to the normal force multiplied by the coefficient of friction between the two rigid bodies.

Ok, yup, that's the def of friction... but the question still remains - does muscular friction increase as heavier weights are lifted? Any thoughts?

Originally Posted by CowPimp

My speculation was that friction durring eccentric movement is actually causing more microtrauma to the muscle.

This is indeed true because the eccentric phase promotes blood flow to the specific muscle being trained. Microtrauma helps in building your muscles even stronger during your rest days, so make sure you do some slow, painful negatives.

Originally Posted by reg56

This is indeed true because the eccentric phase promotes blood flow to the specific muscle being trained. Microtrauma helps in building your muscles even stronger during your rest days, so make sure you do some slow, painful negatives.

I don't understand what all the discussion is about?? I thought this was a known fact, just common knowledge.

Just thought I'd further explain what cowpimp originally said. I know the majority of people already know this, but I figured newcomers would benefit from it.

Originally Posted by SlimShady

Ok, yup, that's the def of friction... but the question still remains - does muscular friction increase as heavier weights are lifted? Any thoughts?

Yes. friction equal to the normal force (the heavier the weight the bigger this number)multiplied by the coefficient of friction between the two rigid bodies. So say you are lifting 50 pounds and say the coefficient is 0.15. The equation would be 50x0.15 thats 7.5 pounds of friction. Now say you are lifting 100 pounds. The equation is 100x0.15, that is 15 pounds of friction. (I think that's what it means at least).