Fast and excessive lymph fluid build up.
Another one of the drawbacks of high pressure pumping.
The lymphatic system has no central circulatory pump like the cardiovascular system. It’s more or less moving around by osmosis. And so the rate at which it builds up in the penis from pumping is directly related to the pressure at which one pumps. So high pressure, faster fluid build up.
The time required to pack the pump at a certain pressure can be a good indicator of gains occurring, but lymph build up in and of itself is entirely a liability in my perspective. It acts like a cushion, decreasing the forces on the target tissues.
Excessive lymph build up looks bad, and it’s probably not great for you either. It takes a while to drain, and it can limit how soon one can do their next workout. I think it can also contribute to skin pain around the donut area, and in the glans, by further stretching the skin.
Pumping at full vacuum magnifies all these problems. The rate of lymph fluid build up, and the overall amount at the end of the workout, are both greater than with normal pumping.
One of the positives maybe, is that the lymph can dampen the intensity of high pressure.
Overall though, it’s a liability. I see two ways to deal with it.
One is to have a well fitting tube. This is what PEforFun recommends. And I think it’s essential if you’re going to do any kind of flaccid or semi-flaccid pumping at high pressure. Mega lymph is going to happen, but at least a well fitting tube limits how much builds up.
The second way, and it’s pretty amazing if you ask me, is to pump erect and pull out of the tube every 10 - 60 seconds. And just do some light manuals. Even just edging. The result is very little lymph build up. Shockingly little.
There are a few things going on. One is that pulling out of the tube completely gives time at normal pressure. Remember that there is a partial pressure with PE4F pumping, even when your thumb is off the hole. So if you never leave the tube, there’s a constant one way street for lymph to build up. Spending half the workout out of the tube gives that lymph time to flow backward out of the penis (because there’s an osmotic gradient in that direction due to the build up in the penis).
Next is regularly refreshing the erection. Being erect limits the amount of lymph that can build up, in a similar way that having a well fitted tube does. There is less space for it. If you just stay in the tube the whole time, it’s at best a partial erection. By refreshing it every 20-60 seconds, it maintains a high erection level while in the pump.
And then it’s also preventing lymph build up by just massaging it. Preventing it from clumping up in the donut area.
When I get done with a 25 minute workout using the 10-20 seconds in the tube / 10-20 seconds out the tube and refreshing erection - there is so little lymph that I could hang an hour or two later if I wanted to. It’s about as much lymph as if I were pumping at 3”Hg instead of 30”Hg. It’s really amazing.
So I think it’s clear which style I favor. That said, there may be some advantages to pumping semi flaccid in a well fitted tube for gains purposes. To each his own. But if we’re talking about the safest and least negative side effects way of doing PE4F pumping, it is definitely by manually refreshing the erection between each cycle. If you don’t use that style, your unit will come out looking like the pillsbury doughboy.