There is a write up about pumping on pumptoys website, in the library bagman’s article "effective time"
TIME AND THE PUMPING PROCESS
Many pumpers feel that they grow fast in the early part of a pump session, then seem to "Plateau" or reach a point where enlargement either stops or greatly slows down. It would seem logical to say that the longer you pump, the larger you would get. Not necessarily true!
The question is one of effective time. "Effective" means any time when the flow and gain of fluids that cause enlargement is taking place at the desired rate, and that is not something that occurs continually. Effective time also varies in the level of efficiency- as the flow reduces, the level drops. Pumping up faster or larger is a factor of effective time only. Time spent in the pump that’s not effective is totally wasted.
This fluid flow and gain process that creates enlargement is restricted by the pumping operation itself, in these three ways:
As swelling takes place, tissues are engorged- including those of the passageways bringing fluid in, actually reducing the diameters of those passageways.
There is a pinching pressure attempting to close these passageways right at the point where the cylinder entry meets your body. The passageways are part of the tissue being compressed by the sealing surface of the tube.
It is further complicated by another easily demonstrated process, that of "vacuum collapse". Take a soft tube, and connect it to your vac pump. With an open end, it will suck indefinitely. Now squeeze the tube down in the middle. As the opening gets narrower, two things happen. One, the flow through the restriction reduces- and two, the vac level on the restricted portion increases. There comes a point where the internal vacuum itself pulls the tube closed- and all flow stops.
All of these conditions combine to either restrict or stop the process of enlargement. The longer the condition lasts, the tighter the restriction can get- and thereby further reducing the level of effectiveness, ultimately ending effective time altogether. The issue is one of making all the time in the pump effective time, and maximizing the level of that effectiveness.
HOW DO YOU FIND OUT WHAT WORKS?
We did an experiment to try and measure the extent of this. To determine exactly what gain was occurring, we went to Displacement Pumping. (Explained in another Advanced Pumping Article) Two pumpers who run close to the same in size and usual enlargement rate provided the comparisons. We selected the one that usually pumped up faster as the control subject; and the slower one as the test subject. Both used STJ’s as cylinders, and both pumped wet with precisely the same level of water in the jar. Both jars were marked for measurement by adding water that had been precisely measured and creating a CC (Cubic Centimeter) scale on the side The scale started with the zero set at the water mark with the jar vertical and inverted, with enough water to cover the pumper. As the enlargement develops, it displaces water and raises the level on the scale- precisely measuring the volume of change. We did this experiment on four occasions using different schedules each time, with substantially different results.
The control subject would pump at a vac level of 5", and hold it for 60 minutes.
The test subject would pump at the same vac level, but would interrupt the session with an alternate state as called for by the experiment schedule.
The result is measured in relative terms:
The change in volume (actual gain) of the test subject, as compared to the control subject expressed as a plus or minus percentage. The volume of the control subject’s gain over the zero mark would always be 100. If the test subject developed 10% less gain, the test score would be 90%. If the gain was identical, the score would be 100%; if the gain was 10% more, the score would be 110%. The "Relative effectiveness" is the score points gained per minute; obtained by dividing the score by the time at level.
Four test schedules were tried, as follows:
Break at 15 minute intervals, exit and massage 2 minutes, return to vac level. (3 breaks)
Reduce vac level to zero once every 15 minutes, hold zero for 1 minute, return to level.
Reduce vac to zero every once every 10 minutes, hold zero for 1 minute, return to level.
Reduce vac to 1" every 5 minutes, hold for 30 seconds, return to level.**********(this method was found to be the best, its #4 on below chart)
Here’s the scorecard of the test subject for these tests:
SCHEDULE SCORE TIME @ LEVEL RELATIVE EFFECTIVENESS
CONTROL 100 60 MINUTES 1.66
#1 108 54 MINUTES 2.00
# 2 111 57 MINUTES 194
# 3 121 54 MINUTES 2.24
# 4 133 54 MINUTES 2.46
SO-WHAT DOES IT MEAN?
In every schedule, taking breaks to restore circulation and relieve the closure resulted in faster net gain. Frequent reliefs of vacuum for short intervals are the most effective overall. The indication is that a sort of pulse-pumping with intervals is far more effective than constant pressure. It’s also logical to conclude that if the test had run for a two-hour period, the second hour score increases would have been greater than the first, because the loss of effectiveness in the control subject would be somewhat accumulative or progressive.
One other note- the subjects were sitting and not active during the tests. Activity would help relieve some of the restriction problems. It’s commonly recognized that being erect while in cylinder is more effective than a sitting position. This is due to the weight of the cylinder pulling downward, helping to reduce the pressure the vacuum can exert against the body in the seal area, thereby creating less restriction to fluid flow.
If you feel you have reached your "plateau", try the take-a-break system; get your fluid passages open again, and- pump on!