Constant versus Cyclical Tension: Which is More Effective?

New restorers often ask whether manual methods or devices are more effective at growing skin. Although this is a reasonable question to ask, it is not exactly the best question to ask in terms of figuring out the best way to restore. Manual methods and devices are just different ways to grip the skin and apply tension. The main difference between the two is that devices are typically used to apply constant tension, while manual methods by their nature are typically used to apply cyclical tension. I think the important variable to look at is whether constant or cyclical tension is more effective at growing skin.                                      

In medical settings, skin expansion is always done with constant tension, 24 hours a day, usually with the tension being increased about once a week. As a result, almost every study done on skin expansion has used constant tension. There is one study that was done on mice showing that cyclical tension was more effective than constant tension.(1) However, to really understand the results of this study, we have to look more closely. One of the issues with the study is that constant tension was done for 4 days, and cyclic tension for only 8 hours. The conclusion that cyclic tension is better was based on extrapolation.

When cyclic tension was used, moderate tension resulted in a 3-fold proliferation of cells after 8 hours, and low tension resulted in a 1.8-fold increase in cells after 8 hours.(1) When constant tension was used, there was a 2.8-fold increase after 4 days using moderate tension, and a 4-fold increase after 4 days using low tension.(1) The authors concluded that this meant cyclical tension was better since it produced similar results in much less time. However, this is based on the assumption that proliferation would have maintained at this rate long term. Interestingly, in the constant tension group, proliferation in the moderate tension group peaked at 2 days, and started to slow down afterwards, whereas the low tension group had slower and steadier gains, overtaking the moderate tension group by the end of 4 days.(1) Similar results were seen when looking at vascular growth. After 8 hours, cyclic tension out preformed constant tension. In the constant tension group, vascular growth peaked at 2 days, and slowed thereafter.(1)

Had the cyclic tension group been measured out to 4 days as with the constant tension group, it is possible that proliferation would have continued at the same rate seen after 8 hours, but it is also possible that it would have slowed down as seen in the moderate constant tension group. Given that foreskin restoration takes thousands of hours, a study done for only 8 hours is in no way conclusive at determining the effectiveness of cyclic and constant tension over long periods of time. The only conclusion that can be drawn is that low constant tension outperforms moderate constant tension over time, but again, this was only after a short period of 4 days.

Also, as I have covered earlier, foreskin restoration is very different from regular skin expansion because of the presence of the dartos fascia. Because of this, I don’t think we can draw any conclusions either way about constant vs cyclical tension based on any available research. I do however think that it is worth experimenting with. 

I would also like to point out that in the mouse study that is often cited, tension was used 2 hours on and 1 hour off.(1) This is very far off from the schedules that most manual restorers use. Most manual restorers usually apply tension for several minutes at a time with an hour or more of rest in between. Also, manual restorers often use retainers or packing methods like o-rings in between, which do provide a constant, low amount of tension.

On the flip side, restorers who use devices aren’t exactly using constant tension either. Unless you are restoring at night, which I do not recommend for safety reasons, tension is not truly constant. Applying tension for 16 hours a day and resting for 8 hours at night is about the closest you can get to constant tension, but it is still a cycle. Although I can confidently say that men who restore during most waking hours at a comfortable tension tend to get good results, it does not mean this is the most effective cycle. It could be that applying tension 2 hours on and 1 hour off during the day is more effective. The number of possible cycles is endless, and different combinations may be worth trying, especially if you have a daily schedule with natural breaks anyway where it may not be feasible to restore at certain times.

There is also a common misconception that skin growth only occurs during rest periods. Medical skin growth uses 24-hour constant tension, so we know that this isn’t true. As for the dartos fascia, we currently don’t know for certain how the smooth muscle cells proliferate during restoration, but I have speculated how it probably occurs here and here. Smooth muscle proliferation is very different from how skeletal muscle grows in response to exercise. In skeletal muscle hypertrophy, exercise damages the muscles, and then they grow back larger during rest. However, there is no proliferation of skeletal muscle cells; the existing cells only grow larger. In foreskin restoration, mild mechanical stress does cause smooth muscle cells to proliferate, meaning that we are actually growing new cells and new tissue. The dartos fascia is probably expanding in much the same way that skin does, just at a slower pace.

At this point in time, there is enough evidence to say that both constant and cyclical tension work, but not enough to say one is better than the other. In The Complete Guide to Foreskin Restoration, I generally recommend using constant tension with devices or tape because it requires the least amount of active time per day. To date, I would say that the majority of men who have completed restoration have used constant tension during waking hours. It makes the most sense according to what we know about medical skin expansion, but it is also just the easiest schedule to follow. Foreskin restoration is a multi-year process, and maintaining a consistent schedule is much easier with passive tension. Manual methods require more active time per day, and this can make compliance difficult for all but the most dedicated. I think that the primary factor on deciding which to use should be whatever fits into your daily schedule the best, but for those interested, different tension cycles are worth experimenting with.

References:

1. https://pubmed.ncbi.nlm.nih.gov/17968184/

Image: Comfr, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons