I think I need to preface this by noting that on the face of it, this may sound odd. However, there exist a plethora of irrelevant results any time I've searched for this, due to the nature of the related keywords, and I don't have access to any medical databases to help me avoid the dross.

So. I'm an engineer by trade and I had a thought about a health product which I think could improve a lot of lives. I'm still in the concept stage and I'm looking into the feasibility of what would be required, from a technical perspective, for this product to function as-intended. Basically I am attempting to ballpark the specifications so I can bound the scope of the problem.

In order to do this, it would be exceptionally helpful if I could find numeric data regarding "typical" forces/pressures produced by human genitalia over time and/or under different conditions. I.e., durometer-equivalent measurement of penile stiffness vs. time and vaginal radial contraction pressure vs. time (and vs. position would be best, but those data may be challenging to obtain from an instrumentation perspective.)

So the question is this: might such data exist somewhere? Perhaps in some esoteric journal on human sexuality that might not be well-known outside that field? Or is it not likely to exist?

I might be able to develop instrumentation to estimate these data if they do not exist, but I fear that it may strain my relationship with my partner to request that she use said instrumentation... not to mention that it'd take a while to figure out how to keep the instrumentation relatively inexpensively while still medically safe to use.

My gut tells me these aspects of sexuality have been quantified, because many stranger things were quantified back in the 70's-90's, but I haven't been able to find anything about it on my own.

  • You'd also need to account for between-subjects variation. I was able to find within seconds the forces at birth, but the other ones are harder to find indeed.
    – Fizz
    Oct 17 '21 at 8:03
  • @Fizz I imagine there might be significant variation between individuals, primarily women, since things like pelvic-floor exercises can increase those forces like any other muscle. I'm primarily looking for a "mean" in some sense right now though, since I have no clue even what order of magnitude is typical. With men, I would imagine that the upper limit of the stiffness is bounded by the systolic blood pressure of the individual since it's more of a balloon than a muscle. Oct 17 '21 at 8:36

I think this may be what you're looking for on the woman's side.

Vaginal tactile imaging (VTI) allows for acquisition of bilateral pressure patterns along the entire length of the vagina. [...]

Data were analyzed for 42 subjects with normal pelvic floor support from an observational case-controlled clinical study. The average age was 52 years (range = 26–90 years). We introduced 8 VTI parameters to characterize vaginal conditions: (i) maximum resistance force to insertion (newtons), (ii) insertion work (millijoules), (iii) maximum stress-to-strain ratio (elasticity; kilopascals per millimeter), (iv) maximum pressure at rest (kilopascals), (v) anterior-posterior force at rest (newtons), (vi) left-right force at rest (newtons), (vii) maximum pressure at muscle contraction (kilopascals), and (viii) muscle contraction force (newtons).

enter image description here

That image is for insertion. The also have some similar ones for rotation and some snapshots over time for contractions. And some numerical figures are provided for many of those scenarios & parameters. There should be plenty of data to get you started. (I don't know if there are significant differences during sex or if the fact that the probe was fairly rigid makes a lot of difference.)

For the male side, you could probably look at almost any paper on erectile dysfunction measurements... as long as it has some healthy controls, e.g. see table 2 in Cheng et al.; it has elasticity measure (Young's modulus) for the two main parts of the penis at various "grades" of erection. I suspect there are papers that have more fine-grained data, i.e. measure at more than two points.

  • Ah! This is almost precisely what I was looking for! I have no idea what you searched or where you searched to find this but thank you! Oct 17 '21 at 8:39
  • @KennethAtkins finding hidden gems is an art. :D Oct 18 '21 at 8:07
  • I'm no expert, but "resistance to insertion" is not generally an important part of good sex. The contractions during orgasm might in theory be interesting to measure. Oct 19 '21 at 18:13
  • @KateGregory For the purposes of my concept, I'm interested in both. From the linked paper, though, I think I have enough relevant keywords to find some other useful stuff. Oct 20 '21 at 5:33

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