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Girth theory: Pumping vs. clamping

Originally Posted by mravg

The stress you can apply with clamping is probably greater because there is less of a negative effect on the other structures from the internal pressure, and the pressure is mainly just effecting the tunica.

I wonder whether that is correct since the blood vessels and NERVES are running right under the skin and are under high stress under a clamp. My personal impression and may be that of others (Mr. Happy, I think) would be that clamping is riskier than pumping but probably more effective (see the current poll I mentioned earlier, with a link).


Later - ttt

Originally Posted by SteadyGains
One caveat I would add is that when clamping at full erection, the capillaries in the skin are stressed to the max as well. There are harmful effects caused by the clamping that is not caused by pumping.

I would not care some much about capillaries (the smallest blood vessels) but the arteries (bring in the blood and have the high blood pressure required for a good erection, and the nerves, also required for erectile function but beyond that, may cause numbness when damaged by clamping - which would be very unlikel while pumping even at high pressure.


Later - ttt

Originally Posted by petrus425
Happy new year!

Bonne annee a toi et a tous les autres.


Later - ttt

Originally Posted by marinera
My feeling is that mravg is right on this specific point. Even when clamping, seem to me that a minimal flow exist in the penis.

A 100% erection could maybe cease any blood-flow, but a 100% erection is near an ideal thing. Erections we have the most of time are under 100% of intensity.

But, returing on the topic of this thread, there is any difference in pressure effects on tunica, when pumping Vs. clamping?

I agree. With the hardest of erections, I never see discoloration, or darkening. With high pressure clamping, where I clamp to where I can neither kagel in any more blood or get any leakage of pressure…I get darkening.

I have always assumed that the darkening indicated lowering of the O2 levels in the blood of the penis, which indicates slowing or stopage of blood flow.

Based on this, my assumption is a normal hard erection may slow circulation, but not enough to cause critical oxygen loss, at least not for hours. High pressure clamping can cause it within minutes…hence the safety recommendations of time limits when clamping.

Now how much circulation is needed to maintain normal color, who knows? But based on some of the info posted here, it may not be much.

Once again, if we are only talking about generating highest pressures safely, then clamping is superior. However, I’m not entirely convinced that higher is better.

Again, I feel there may be two general effects here, and probably quite a bit of overlap. One, stretching of the tunica, and two, cellular stimulation.

I agree that clamping can more effectively generate higher expansive forces on the tunica, but I don’t know if its been determined that is is producing greater overall success. And by success, I mean total gains, rate of injury and time needed for gains.

Hell, don’t get me wrong, I’m not a advocate of any particular PE approach, I’m all for safe, quick gains. You show me what works best and I’m on it. My point again is I haven’t been shown that higher pressures directly relate to greater success. The PI concept is based on the fact that we are dealing with living tissues that react in a number of ways to stress, not all of them productive to gaining size and improved function.

Like I had alluded to before, that most successful pumpers report that modest vacuum forces work far better than high ones. This alone tends to indicate that its not a direct relation of higher forces equal better gains.

You always need to factor in tissue responses, not just injury but adaptive mechanisms to stress that may actually cause loss of size out of survival responses.

So, really the question is are guys getting more bang for their buck out of clamping? I actually am interested it the answer.

Pardon my delay in responding, been a little busy.

Originally Posted by mravg
Pudendum, I appreciate your knowledge of erectile physiology. I don’t pretend to know that much about it and don’t intend to question what you say. You provide good references. Blood flow in the penis during erection is apparently very low, or zero, but there is a big difference between zero, as stated in your first reference, and almost zero, as stated in your second.
Sure the penis can withstand low oxygen for “some time” but how much time is that? How much flow is almost no flow? I would guess that even very miniscule flow through the penis during marathon sex can do a lot to prevent oxygen deprivation.

Well, you answer your own question in your next sentence.

There you go. That doesn’t happen with the balloon. Actually it is more accurate to say that blood is forced into the penis by the heart, facilitated by less external pressure on the tissue, allowing it to expand.


It appears that you and others have not read my statement in an earlier post in this thread in response to Mr. Happy:

Originally Posted by pudendum
Understand that I picked a very discrete point in the erection; max.

The penis is not a simple system. You add the real issues of tunica compliance the decreases as the erection approaches max. You are not placing a direct inward force on the penis when you pump, you are in fact doing the opposite. This is why the clamp should have a greater effect at PEAK erection.

Again, I have no doubts that pumping works at lower levels of erection and I do not dispute success. But to get an understanding of a complex organ like the penis which to say the least undergoes dynamic changes experienced nowhere else in the body, you must break things down into discrete subsystems and/or situations. I picked peak erection to try to get some handle on that specific phase.


It is important to understand my posts in light of this. In my opinion, the dynamics of the penis at any other time (except when flaccid) is very complex and until we understand the penis at very specific times in erection, we’ll have no basis for comparison.

If you chose to disbelieve the experts, who know a lot more than you and I do regarding the blood flow and pressures in the tunica at peak (or skeletal) phase of erection, that’s ok. They’ve done the experiments, had their work reviewed by other experts and then get it published in respected medical journals and textbooks. I haven’t. I tend to believe what when they say.

Tom Lue, MD is a respected expert in erectile dysfunction and Pyronie’s disease. He is a Professor, vice-chairman and occupies an endowed chair in the Department of Urology at the University of California San Francisco School of Medicine. When he says that blood flow entering and leaving the cavernosa ceases at the peak erection, I believe him. What you believe is up to you.

Originally Posted by mravg

Look at it this way: you connect a hose with 60 psi water pressure to a metal tank. there is a pipe on top of the tank with a valve on it. You fill the tank until water is coming out of the pipe, then shut the valve.
The water is still turned on, so there is 60 psi in the tank and hose, but there is no flow in or out.
Now, you magically turn the tank into a rubber walled tank that expands 5% due to the 60 pounds of pressure on it.
The tank has grown in size, water flowed to fill the additional space, then stopped when the system reached equilibrium. The pressure in the tank is still 60 pounds.
That is your penis.


No, that is not your penis at peak erection. Why not? Because the contraction on the cavernosa by the Ishiocavernosus muscles raise the pressure in the penis much higher that the inlet pressure, unlike in your example where tank pressure and inlet pressure are the same (ignoring where the inlet hose is attached). In the penis the cavernosa pressure is 200 - 300 mm Hg and inlet pressure is about 120 mm Hg.

Originally Posted by mravg

Put a giant cylinder over this tank and pull a vacuum. The tank will grow more, water will flow into it, it will reach equilibrium, and the pressure will still be at 60 pounds.


This is not the situation in the peak erect penis. The pressure in the cavernosa probably does drop to some small degree but never low enough to allow new blood into the penis AT peak erection. The movement of blood from the unpumped internal portions of the penis probably move into the pumped penis to cause a small but finite increase in volume-induced wall tension.

Originally Posted by mravg

The balloon full of water is much different:
Take the same example of the full tank.
This time you shut off the hose first with a valve at the tank where the hose connects to the tank. ( a knot in your balloon!)
Then you magically turn the walls in to rubber as before.
The tank grows due to the internal pressure, and as the tank grows, the pressure drops. It reaches equilibrium at some size smaller than the tank in example one, and the pressure is something less than the original 60 pounds.
Now put a giant cylinder over this tank and pull a vacuum. The tank will not grow more as in the first example.


The difference is the pump. The heart in your body, or the pump at your city water department. The balloon is a closed system, and the penis is not, because it is connected to your heart, even if there is no flow, there is pressure applied from the outside, just like that hose connected to the full and closed, tank.


If the vessel pressure is much higher than inlet pressure (blood pressure) than the effect of inlet pressure can be ignored. There have in fact been suggestions that maybe blood flow backwards in arteries because the cavernosa pressure is so high, but this has never been observed. If in your situation the tank pressure was double the 60 psi inlet pressure, flow would probably flow out UNLESS you close the system, like the penis at max erection..

I also notice that you have disregarded my explanation of the energies exerted on your original pipe and on the balloon (and I’ll grant that the change in volume with the change in pressure of a liquid is small) with a negative pressure. It is important to understand the effects of vessel was compliance on whether the applied force (or negative pressure in the case of pumping) is converted to kinetic energy and allows for expansion or whether the wall is so poorly compliant that the effect is only potential.

The tunica is more like the pipe than the balloon, with regards to the wall.

Originally Posted by ticktickticker
I get your point.

But let us look yet from an other angle, or from two other angles.

The negative pressure outside of the penis would increase it’s volume and increase the pressure inside of the corpora cavernosa. This is true but irrelevant for dick growth. The tunica is only interested in wall stress. Wall stress depends on volume, not on pressure.

The other point I made already some time ago is that in pumping the cavernosa are open towards the remaining circulation. Therefore, if the volume increases in the corpora because of tunica expansion there is a net influx of blood into the corpora. The pressure will tend to remain constant.


No. Pressure within the tunica does not rise, it drops. The pump probably causes a very small pulling effect on the wall of the tunica (like mravg’s example with his tank under pressure), decreasing the pressure in the chamber. Why?

In the very specific peak phase of erection when cavernosa pressure is well above arterial pressure, there will not be a net influx of NEW blood into the cavernosa. There will, however, probably be a small increase in volume in the cavernosa from blood in the unpumped penis (from the base to the root). This would be because the pressure of the blood in the unpumped penis (which will be still above arterial pressure) will be higher than in the pumped when the negative pump pressure causes its small effect on the very low compliance tunica. The penis will equalize the pressure by moving blood. This small volume effect might be enough to cause volume-induced wall tension necessary for growth of the circular fibers of the inner tunica to cause growth in girth.

Let me do a simple resume of what are you saying, pudendum, because your post are a bit complex (this is not a critic, of course) and many of readers could be exhausted here:

assuming a 100% erection, once the pressure in the cylinder-pump is zero, blood inside CC can expand tunica with max force. After this point, lowering the pressure inside the cylinder is not really effective for tunica, because it’ s compliance is too low and because no more blood can be pushed inside CC, giving the peak erection physiology.

So, lymph build-up is the main consequence of negative pressure, and this lymph is not stressing the tunica.

Is this right, or I have done errors?

Originally Posted by ticktickticker
Mrvag’s example of a metal tube vs. A condom (with the penis somewhere in between) is a very good concept. All our (sofar often incorrect) use of assumptions and formulas regarding pressure are distracting our view from the essential common point between clamping and pumping:

The V O L you M E effect.

I may be repeating myself, but it is the total volume of blood and the consequently stretched volume of the tunica and related structures that is relevant, because it is the volume change that is transformed into

A W A L L E X T E N S I O N and

A W A L L S T R E S S effect.

I would hypothesize that it is the increased wall extension and increased wall stress that ultimately causes physical deformation and biologic effects, which, in concert induce penis growth.

The volume effects are ultimately consequences of pressure effects, as described quite convincingly be mrvag.

An important difference between clamping and pumping is that the “balloon” is open to the rest of the circulation it the case of pumping, but that the balloon is closed (clamped) in the case of clamping.


I agree that pumping is a volume effect. But the volume effect on the tunica wall with pumping does not require that the penis be an open system with new blood flow as I described in the last post. Blood moves from the umpumped penis because the cavernosa pressure in the pumped area drops.

With clamping the volume increase is a result of increased pressure on discrete areas of the penis causing the movement of blood. Whether the tunica stress with clamping is because of volume and/or pressure-induced tunica stress is another debate.

Originally Posted by mravg
1. It sounds like we have a general idea of how much pressure differential is created by pumping (200mm Hg normal erection pressure + 150 mm Hg caused by the drop in external pressure (6 inches Hg). So the force on the tunica may be close to doubled from normal. I think Pudendum gave us these numbers. But how does that compare to the pressures involved in clamping? I expect clamping creates more pressure, but it would be nice to have some data.


You may but I don’t.

I’ll ask you again. If I apply a positive pressure of 150 mm Hg on the outside of penis that has a chamber pressure 200 - 300 mm Hg, by your logic, the applied pressure should be subtracted from the chamber pressure. You and I know that his makes no sense. Cavernosa pressure will rise, not fall.

So you guys have not explained to me how a negative pressure is added to make a higher chamber pressure. Explain it to me in the peak erect penis with a poorly compliant tunica. The pressure will equalize with the rest of the penis for the reasons I explained before.

My take on the 102% erection question

Originally Posted by Mr. Happy
Oh, and how does one measure 102% erection so precisely, I wonder?

When I clamp even moderately, I generally get an increase in girth from my normal erect girth of 5.875” to 6.25”. That’s a girth increase of .375 inches and occurs from the clamp position outward. Although there is some measure of compression at the clamp location, the increase plugged into the volume equation shows the following:

Normal erection size = 7.5” length and 5.875” girth = 20.819 cubic inches

Clamped erection size = 7.5” length (+) and 6.25” girth = 23.327 cubic inches

That’s a clamped erection size that’s 112% of normal size.

Even if I were to go to the point of calculating the volume decrease at thepoint of the clamp compression, that’s a small portion of the length and I think you get the point.

So I would estimate that I am clamping to a 110% erection over normal. I believe that this deformation of the tunica is where my gains are coming from.

As an aside, I have tried cable clamps that everyone raves about and I hate the buggers. They pinch, wrapping is a pain and they are still hard plastic which snaps under repeated use and kegels while clamped. I also believe the shape issue people have discussed is quite over-emphasized.

I use a trimmed rubber pipe junction fitted with a turn key cable clamp. After trimmed, the edges flair up and away from the penis when clamped and the thing works like a dream with much more precision (sometimes one more click with a cable clamp is too much!). It requires no wrap and works like a charm.

Originally Posted by marinera
Let me do a simple resume of what are you saying, pudendum, because your post are a bit complex (this is not a critic, of course) and many of readers could be exhausted here:

assuming a 100% erection, once the pressure in the cylinder-pump is zero, blood inside CC can expand tunica with max force. After this point, lowering the pressure inside the cylinder is not really effective for tunica, because it’ s compliance is too low and because no more blood can be pushed inside CC, giving the peak erection physiology.

So, lymph build-up is the main consequence of negative pressure, and this lymph is not stressing the tunica.

Is this right, or I have done errors?


Yes. At peak erection there is such a high pressure in the blood chambers, blood flow in and out of the cavernosa ceases and the penis in essence becomes a closed system, so no more new blood can be pushed in. The veins are pinched and the artery pressure is lower than cavernosa pressure. The small effect caused by pumping is by some small pull on the tunica by the negative pump pressure causing blood already in the penis to be pulled into the part of the penis under the pump.

The pressure caused by edema fluid from high negative pressures should not be high enough to have any resisting effect on the tunica, in my opinion.

Is this explanation any clearer?

Originally Posted by sparkyx
I agree. With the hardest of erections, I never see discoloration, or darkening. With high pressure clamping, where I clamp to where I can neither kagel in any more blood or get any leakage of pressure…I get darkening.

I have always assumed that the darkening indicated lowering of the O2 levels in the blood of the penis, which indicates slowing or stopage of blood flow.

Based on this, my assumption is a normal hard erection may slow circulation, but not enough to cause critical oxygen loss, at least not for hours. High pressure clamping can cause it within minutes…hence the safety recommendations of time limits when clamping.

Now how much circulation is needed to maintain normal color, who knows? But based on some of the info posted here, it may not be much.


The arteries and veins to the skin (and the tissues between it and the tunica) are different than those feeding the cavernosa (lets not talk about the spongiosum here because it is different; it has to stay soft enough for ejaculation). Even at peak erection, blood flow continues, so the skin will continue to look pink and healthy.

However the medical information with regard to the cavernosa is different. The arteries and veins of the cavernosa are set up so that as the blood fills and expands it, the veins are pinched and no longer drain. The erection chambers continue to fill until the pressure inside is equal to the arteries filling it. So blood flow in ceases and blood flow out is pinched.

I think I now see the confusion with my statement that blood flow to the penis ceases at peak erection. It is the blood flow to the cavernosa, not the skin and tissues below it. So the penis will continue to look nice and healthy and pink (or whatever color your health penis has).

Thanks for helping me to clarify this, Sparkyx.

Originally Posted by pudendum
Yes. At peak erection there is such a high pressure in the blood chambers, blood flow in and out of the cavernosa ceases and the penis in essence becomes a closed system, so no more new blood can be pushed in. The veins are pinched and the artery pressure is lower than cavernosa pressure. The small effect caused by pumping is by some small pull on the tunica by the negative pump pressure causing blood already in the penis to be pulled into the part of the penis under the pump.

The pressure caused by edema fluid from high negative pressures should not be high enough to have any resisting effect on the tunica, in my opinion.

Is this explanation any clearer?

Thank you.
I basically agree with your explanation, but there is a little problem :

it should be a consequence of that explication that mild erection would be more beneficial, when pumping, if I’ m not wrong in something. Adversely, as ThunderSS pointed, and near every guy who tried pumping could agree, when pumping there is more lymph build-up with lower intense erections than with peak erections.

This is why I supposed that others tissue than tunica could augment their volume more easily than tunica, so the effect on these tissues are worse then when we clamp, and effects on tunica are lower.

But it seem you don’t agree.

So, what are we missing?


Last edited by marinera : 01-04-2008 at .

Originally Posted by sparkyx
Once again, if we are only talking about generating highest pressures safely, then clamping is superior. However, I’m not entirely convinced that higher is better.

Again, I feel there may be two general effects here, and probably quite a bit of overlap. One, stretching of the tunica, and two, cellular stimulation.

I agree that clamping can more effectively generate higher expansive forces on the tunica, but I don’t know if its been determined that is is producing greater overall success. And by success, I mean total gains, rate of injury and time needed for gains.

Hell, don’t get me wrong, I’m not a advocate of any particular PE approach, I’m all for safe, quick gains. You show me what works best and I’m on it. My point again is I haven’t been shown that higher pressures directly relate to greater success. The PI concept is based on the fact that we are dealing with living tissues that react in a number of ways to stress, not all of them productive to gaining size and improved function.

Like I had alluded to before, that most successful pumpers report that modest vacuum forces work far better than high ones. This alone tends to indicate that its not a direct relation of higher forces equal better gains.

You always need to factor in tissue responses, not just injury but adaptive mechanisms to stress that may actually cause loss of size out of survival responses.

So, really the question is are guys getting more bang for their buck out of clamping? I actually am interested it the answer.


I believe you are very right here. The effect on, let’s say the tunica, to different PE methods and intensity is a matter of degree. The tension-induced connective tissue remodeling mechanisms are the same for small stresses as they are for intense injury induced stress (though there are more white blood cells and other inflammatory cells involved with injury). The bodies physiologic response to these stresses will also be a matter of degree.

As you have already explained well in your PI article, the body will tell you what it “thinks” about the stresses and methods you use. Sensible PE and close monitoring of the bodies physiologic response are the true keys to success.

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