Girth theory: Pumping vs. clamping

I have much more important things to do than to read about penis physiology, yet that is what I have been doing, and I have learned a lot, and I think answered some questions that have been lingering here. To start:

The question about whether or not blood flows during peak erection is not so simple. The answer is actually yes, and no!

As pudendum has pointed out, the ischiocavernosis muscle (ICM) contracts, which raises pressure in the CC’s above normal arterial pressure. This pressure can in fact cause complete stoppage of venous outflow.

However, studies have shown that ICM contraction is intermittant:

The intermittant contractions allow maintenance of pressure, as well as some inflow and outflow of blood to prevent the oxygen deprivation that we have been discussing!

These quotes were taken from the discussion section of this excellent paper:

http://www.andr ologyjournal.or … l/27/5/695#SEC2

Pudendum, in our discussion of your balloon model, and my tank model, I now think neither one is correct.

As you pointed out, the hose connected to my tank represents the arterial inflow at normal arterial pressure. Since the tank (CC) pressure is higher than this hose (arterial) pressure, this hose can not fill the tank.

The balloon model is also wrong because it doesn’t allow for inflow or outflow, which we know happens.

However, I think we can modify the tank model to be accurate if we add a linear peristaltic pump between the hose and the tank entrance, which is used as a "second stage" pump to pump at higher pressure. That is how I view the ICM intermittant contractions; a secondary pump that keeps the penis pumped up at higher pressures than the normal arterial pressure.

I think I am coming to a more clear picture of how vacuum pumping and clamping work differently, which I will post later.

One man’s expert is another man’s heretic.

If your interested, I have several references that talk about markedly elevated cavernosa pressures resulting from maximally full cavernosa and then the contraction of the paired Ischiocavernosus muscles that surround the cavernosa.

Pressures are as high as 200 - 300 mm HG.

I agree. I too think the reason the guys can marathon without discoloration is because there is some reduction of erection for relaxation of the Ischiocavernosus muscle and some venous outflow leading to new blood in through the arteries to the cavernosa.

In addition, since the pressure in the skin and the tissues under it do not climb above arterial pressure and the main vein does drain, the skin stays nicely colored throughout a gymnastic night. Now stick a clamp on it and stop blood in and out of the skin, that is a different story.

Yes. Yes he is.

Yes. Yes it is.

Exactly, the outflow can be stopped, but is the inflow stopped by the same process? My theory is that pumping will “suck” additional blood into the CC as well as some leaks out due to low intensity erection. I believe Pude is saying that the pump simulates the peak erection so the pump could only be pulling lymph fluid into the tube, not additional blood into the CC.

It is important to be clear on this point in order to further the discussion about pumping vs. clamping, so I will discuss this a bit more.

I never said that negative pressure outside the penis will increase pressure inside the penis. I was discussing pressure differential between inside and outside. It is the differential that determines how much stress is on the tunica. If you have 1000 psi inside but 1001 psi outside the penis, then the penis is collapsed and you have no tunica stretching, despite the high internal pressure.

Yes, and I hope now you see that it is true if we are discussing the pressure differential = P inside minus P outside.

So if you have 200mm inside and then you increase your cylinder pressure to 150mm above atmospheric outside, then you have 50 mm Hg differential. The differential is reduced from the original 200, so you have less force from inside stretching the tunica.

You are right. For your balloon model, which works for this example, positive pressure outside the balloon increases the pressure inside, but decreases, or fails to change, the pressure differential. The rigidity of the balloon wall will determine how much the pressure outside effects the pressure inside.

I think I know what you are getting at. Let’s look at a condom filled with water and a knot in the end.

There is a pressure on the water. Since there is no external source of pressure or flow, the pressure inside is a function of the elasticity of the condom wall, and the air pressure pushing on the condom wall.

If you put this water balloon in a vacuum cylinder, the pressure inside is still P(elasticity) + P(air pressure). Air pressure decreased so pressure inside decreased!

This example is different than the one where there is an external hose or pump attached. We were envisioning different models, so we came to different conclusions.

If you imagine the model of the tank with the hose and the booster pump (analgous, I hope, to the erect penis with ICM contracting to maintain pressure), then I look at it this way:

The pump maintains a constant pressure. Let”s say in the case of the erect penis it is 200 mm Hg.

Now there is one extra factor in the pressure inside the penis compared to the water balloon above.

Pressure(CC’s)= Pressure (wall elasticity) + Pressure (air pressure) + Pressure (Pump pressure).

Now you put the penis in a cylinder and pull a vacuum. The air pressure part of the equation goes down, but the pressure in the penis probably doesn’t because the pump (ICM contraction) is maintaining pressure.

However, the differential between inside and outside is now greater, because P(inside) is the same, but P (outside) is less.

Again, it is the differential that tells us that the force on the tunica has increased.

Well, if you imagine the model of a full tank with a hose coming in and a hose going out, if you pinch the exit hose, the incoming flow also stops because there is no where for additional water to go unless the tank stretches from the incoming water pressure.

This continues what I was saying in my last post. As I described, the vacuum in the cylinder results in more force pushing out on the tunica. If this force is enough to stretch the tunica (increase the total volume of the penis), then more blood will enter to fill that volume. So in essence, you are right, the vacuum sucks more blood in, but I don’t like using the term “suck”, except with my wife. :)

OK, we seem to have that sorted out…how about a monkey wrench tossed in the works.

I have been thinking about how jelquing with seemingly modest pressures can cause increased girth, and the phenomenon of the tissue under the clamp expanding best ( search Elliptical Strain in Aristocanes thread).

What I’ve been thinking is that PERHAPS because the tunica is essentially a wall or cylinder of fibrous tissue, that putting it under full pressure STRENGTHENS the wall and makes it more resistant to deformation.

The example I am thinking of would be imagine a balloon made of Kevlar fibers. If you inflate it to high pressure, trying to puncture it or more precisely, trying to pull apart the fibers with your fingers or a blunt instrument would be far more difficult than if it was un-inflated or at least partially uninflated.

PERHAPS, its the separation of the fibers from each other, or at least expanding the fibers in relation to each other that is the key. When you jelque at partial erectile levels, you are allowing enough “slack” in the fibers to allow you to make changes of the fibrous “mat” or stretch them apart slightly in relation to their normal inter relationship.

When you have a full erection, or beyond full erection, the fibers are pulled tight forming a very tough wall. Then it depends on the total strength as to whether it will deform enough with clamping or pumping to make progress.

I think it may well be that guys with very tough tunica may respond better to jelquing than high pressure clamping, because having part of the tunica unstressed will allow fibers to be moved or “spread apart” far easier in the part that is being stressed.

Just as the Elliptical Stain formed by the clamp, focuses greater stress on the area under the clamp, perhaps by lowering the overall “taughtness” of the tunica mesh, it is easier to make changes to other areas of the tunica.

I totally agree. This is why I picked a very specific point in the erection process that is reproducible in most guys who have the ability to reach max erection; particularly if you’ve been doing girth PE for a while. If you understand the situation with regards to the effects at this phase of erection, you can better decide when to apply the PE method you are going to use.

I also agree that after this long convoluted and sometimes confusing discussion in this thread, I think that most (but probably not all of us) would agree that a pump should be applied at a lower level of erection than peak. AGAIN, I will repeat that I am not saying that some volume-induced tension to the tunica is not possible at peak erection. I believe it is small. Success by pumpers in my mind proves that there must be.

You are misunderstanding me. I am talking about placing pump on a rigid max penis to start.

I don’t doubt that you will not bring your semi erect penis to max erection in the pump. If you remember what I have said in previous posts is that the pump probably has its greatest effect at lower levels of erection. This must be true because there are so many guys writing about pump successes and if most guys, like you, “find it near impossible to come close to a peak erection inside a tube.”

You know, bumblebees can’t “technically” fly either. ;)

Exactly, the tunica is a viscoelastic structure made up of dense connective tissue with a small elastic component. It has two layers, an inner layer with its collagen (and other fibers) arranged in a circular pattern (circumferential) and an outer layer with fibers arranged length-wise (longitudinally)

At peak erection you are extending the fiber lengths to their maximum, most probably in the inner layer though you cannot rule out an effect on the length-wise fibers (which probably explains length growth with pumping), overpowering the elastic component of the tunica. This is why compliance is very low at peak erection.

I don’t dispute that pumping is a time sensitive method. Again, I don’t dispute that at lower levels of erection this is more than likely very true.

By the way, in my discussion, I believe that I said that the effect of pumping at peak effect would be a volume effect, for the reasons I have expressed ad nauseam (vomit, cough, sputter, dry heaves!! I think I feel better now).

Great article, thank you for posting it. Interesting methods. As I told Stage in another thread, no ones going to stick needles in my penis unless I need it. But there are others who are more daring. that leads us to this report.

Great study design (though there are limitations) and amazing they got volunteers. There has always been discussions of cultural differences in pain perception. I’d think you’d be hard presses (hopefully not too hard, that might hurt as well) to get 18 American guys to volunteer unless they were well compensated. Even then I wouldn’t let anyone wave multiple needles around my penis, especially not on more than one day.

There are interesting results that they found in this study.

First, I know you’re going to say that the pressure inside the cavernosa (which they called ICP) was only 90.6 (plus or minus) 10.7 cm H2O (about 66 mm Hg). They used a 28 gauge needle to poke the tunica (ouch!). The dampening effect of this very small gauge needle would abolish the high and low pulsations to the effects of the beating heart (systolic and diastolic pressures), so all they would see is a mean pressure. Their diagram shows this to be the case Their 66 mm Hg pressure at max filling correlates with the mean pressure seen in the arteries of the rest of the body, so this pressure is the point where no further blood enters (because in inlet and cavernosa chamber pressures are equal).

What is interesting is that when the Ischiocavernosus muscle relaxed, the ICP was 86.3 (plus or minus) 8.6 cm H2O. The plus or minus difference that they report is standard deviation. If you have a working understanding of statistics, you will see that there is no statistical difference between the ICP at the point they call maximum filling and the ICP when the Ischiocavernosus muscles were relaxed. They do not report this (interesting). Is there a change in cavernosa volume at these 2 different times? Don’t know. they didn’t measure it. Does new blood come into the penis? It is interesting that they had a needle in the penis and they didn’t draw off any blood to send to look at the oxygen pressure (partial pressure of oxygen or PO2) in the cavernosa and compare it to a PO2 of blood taken from an artery in the wrist. This would have allowed them to say whether or not new blood with oxygen was bathing the inside of the cavernosa.

Their study is also limited because they do not take any measurements which would tell us about whether there was any blood flow out of the penis. A pressure in the cavernosa equaling mean arterial pressure presses on the veins that drain the cavernosa because the walls of the distended blood pools in the erect cavernosa pinch these draining veins (called the emissary veins) shut. So is there any blood in or blood out in their study? Don’t know.

I bring up these questions because older studies differ from this one. The authors write this hypothesis for there study:

Their study design allowed them to prove their hypothesis. Nice job.

However, you notice they did not hypothesize that the reflex contractions of the Ischiocavernosus (and Bulbocavernosus) muscles cause a rhythmic changes in pressure leading to blood exchange in the cavernosa and normal levels of oxygen.

I’d be willing to bet they tried when they first submitted this manuscript but the journal reviewers corrected their error. Having been both a writer and reviewer, I know what I can try to get away with as a writer and what I won’t let an author get away with as a reviewer.

Why is this important? They did not design their experiment to answer this extension of the hypothesis that they actually presented. They did not design their study to answer this hypothesis. They did not make measurements to prove this (and disprove older studies). Don’t get me wrong, this is a great study and I applaud the authors and particularly the volunteers for this investigation. But there are limitations

You can say just about anything in a discussion section (within reasons). I think that their suggestions that this may be a mechanism to keep the cavernosa tissues happy during rigid erection is definitely worth investigating and if true, it would change the mainstream urological and physiologic understanding of the penis at peak erection. I think they should proceed to study this further .

It is also interesting that since this was published in Sept/Oct 2006, this article has not been cited by any other articles or textbooks written since then (Web of Science - Science Citation Index; which is up to date to within 2 weeks of today). Unfortunately it may reflect a chauvinism of scientists particularly in the USA) to the work of others outside their country or to who they consider practice inferior science. Unfortunately this is a very common problem in medical research. I think it stinks and I try not to practice it myself. I think that science can be good where ever you do it and whatever language you speak.

mravg, thank you for finding this report. I think it elevates the discussion.

You’ll see in my evaluation of the study that you presented, that it does not prove or disprove whether blood enters or leaves the cavernosa at peak erection. I still am not convinced. We may end up agreeing to disagree on this point. The data just aren’t there to definitely prove or disprove either of our contentions.

Interesting thought. However, I don’t believe your model stands up for this reason. You are proposing a secondary pumping action in the inlet line (that being the arteries that feed the cavernosa). At peak erection, when cavernosa and arterial pressures become equal (the valve is now off), the Ischicavenosus muscles compress the cavernosa, not the arteries that feed it.

A more appropriate model would be to put a compressing mess over 1/3 to 1/2 of the tank and begin to compress it after turning off the valve. My alternative surmises that the compressing mesh can affect a change in the tank wall and transmit it to the fluid within (kinetic energy not just potential energy).