The Ischiocavernosus Muscle: What Makes an Erection Rigid
The ischiocavernosus is the muscle that makes an erection rigid. There are two of them, one on each side, and each wraps one root of the penis where it attaches to the pelvic bone. When they contract during an erection, the pressure inside the penis can rise far above your blood pressure. In nine men measured during an erection, voluntary squeezes raised it by 100 to 525 mmHg.[1] Normal blood pressure peaks at around 120.
Blood flow fills the penis. The ischiocavernosus is what turns that filled penis hard.
Where it is
The shaft of the penis is built on two long spongy cylinders, the corpora cavernosa. Inside the body they split apart and anchor to the lower edge of the pelvis on each side, just inside the sit bones. These anchored parts are called the crura (one crus each).
Each ischiocavernosus starts at the sit bone and covers its crus like a sleeve. You can’t see or touch it directly, but it sits in the area between the scrotum and the anus, toward the sides.
What it does during an erection
An erection has two stages, and they use different machinery.
Filling. With arousal, the smooth muscle in the arteries and spongy tissue of the penis relaxes, blood rushes in, and the penis swells. The pressure inside climbs to roughly your blood pressure. This stage is driven by blood vessels and nerves, and the pelvic-floor muscles play no part in it. Recordings with needle electrodes found the ischiocavernosus silent during an erection from visual arousal alone.[2]
Rigidity. A penis at blood pressure is full but bendable. To get past that, something has to squeeze the blood that is already inside. When the ischiocavernosus contracts, it compresses the crura, and because the blood can’t escape quickly, the pressure in the whole shaft spikes. Physiology reviews describe the penis gaining extra rigidity when the ischiocavernosus contracts.[3] A 2014 review by sexual-medicine specialists says the pelvic floor raises the pressure “above maximum inflow pressure to achieve full penile rigidity”.[4]
The muscle fires in bursts: during thrusting, during touch, and whenever you squeeze it on purpose. It isn’t held the whole time, which is why stamina matters as much as peak strength.
What happens when it is weak
A weak ischiocavernosus can’t push the pressure as high, or can’t keep doing it. The erection gets full but not fully hard, or starts hard and fades during sex. Men often describe being “about 80%” or losing it when they change position.
Nobody has shown that a weak muscle causes erection problems on its own. What the trials show is that training it helps many men. In the best randomised trial, men who trained their pelvic floor for three months scored 7 points higher on the standard erection questionnaire than men who got lifestyle advice only, and after six months 41 of 55 had improved and 22 were back to normal.[5] The full trial results are in Do Kegels Help With ED?
If you rarely get hard at all, even in the morning, the problem is more likely the filling stage. The muscle can only squeeze what has already filled.
How to find it and train it
You can’t contract the ischiocavernosus on its own. It fires together with its neighbour, the bulbospongiosus, and the rest of the pelvic floor. What you can do is use cues that bring in the muscles at the base of the penis rather than only the back passage. In a study of young men watched on ultrasound, cues like “shorten the penis” and “lift the scrotum” got over 91% to contract the right muscle.[6]
- Sit or lie down with your stomach and buttocks relaxed.
- Pull the base of your penis in toward your body, as if shortening it, and lift your scrotum.
- If it is working, the base of the penis twitches in and the scrotum rises.
- Hold for a few seconds while breathing normally, then let go fully.
For rigidity, train two things. Strong holds, building toward 10 seconds, are the squeeze that raises the pressure. Quick, hard flicks match the bursts the muscle makes during sex. The trials used both, twice a day, made harder week by week for three months.
Common questions
Is the ischiocavernosus part of the pelvic floor? Yes. It belongs to the outer layer of the pelvic floor, together with the bulbospongiosus.
Can I train it with ordinary kegels? Mostly, yes, if the cue is right. “Stop the flow” or “hold in gas” cues lean toward the back of the pelvic floor. “Shorten the penis” brings in the muscles at the base.
How long until it gets stronger? In Dorey’s trial the measured gain came at three months, with no significant extra gain by six.[5] Plan on twelve weeks of daily work.
Where Sahara fits
Sahara’s Full Strength Protocol trains the ischiocavernosus with holds and flicks that get harder on a set schedule over twelve weeks, the same pattern the trials used. It takes 5 minutes a day, sends a notification at the times you choose, and tracks every session. How all three muscles work together is in The Three Muscles Behind Every Erection.
References
- Lavoisier P, Courtois F, Barres D, Blanchard M. Correlation between intracavernous pressure and contraction of the ischiocavernosus muscle in man. J Urol 1986;136(4):936–9. PubMed
- Gerstenberg TC, Levin RJ, Wagner G. Br J Urol 1990;65(4):395–402. PubMed
- Clement P, Giuliano F. Anatomy and physiology of genital organs: men. Handb Clin Neurol 2015;130:19–37. PubMed
- Meldrum DR, Burnett AL, Dorey G et al. J Sex Med 2014;11(5):1208–20. PubMed
- Dorey G et al. Randomised controlled trial of pelvic floor muscle exercises and manometric biofeedback for erectile dysfunction. Br J Gen Pract 2004;54(508):819–25. PubMed · Full text
- Ben Ami N, Feldman R, Dar G. Verbal instruction for pelvic floor muscle contraction among healthy young males. Int J Environ Res Public Health 2022;19(19):12031. PubMed
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Educational content, not medical advice. See a clinician for pain, blood in urine, or sudden changes. Results vary; the cited trial reflects its study population. Sources for every figure are available on request. Erection problems can be an early sign of heart or blood-vessel trouble, so see a doctor as well.