First of all, it’s important to know that, contrary to popular belief, your so-called love muscle doesn’t contain any muscles (and definitely no bones) — that’s why you don’t have much physical control over its movement. The penis is really more like a sponge, which fills up with blood when a man is sexually excited, or in the right stage of sleep.
Blood builds up inside two cylinder-shaped chambers, causing the penis to swell and stiffen, blocking off the veins that normally carry blood away to other parts of the body. It’s at this stage that most of us first become aware of our ability to flex it — a sort of lurching movement that seems like it should be accompanied by a cartoon spriiing sound effect. Later, you’ll notice you can do it while you’re soft, too, making it look as if your penis is retracting slightly.
But what’s the point of this minor magic trick?
“When you’re erect, your penis does have the ability to flex naturally to allow proper penetration,” says Jamin Brahmbhatt, a board-certified urologist. “It’s a natural evolutionary process that allows humans to use it when you want to and make your penis a little bit more mobile.” The concept, Brahmbhatt explains, is akin to the way tall buildings are built with a little bit of elasticity in case of an earthquake. “Skyscrapers are built to be able to sway a few inches to the right and left in case of an earthquake or high winds — the flex in your erection is similar to that.”
As mentioned earlier, despite how it feels, you aren’t actually flexing any muscles in your penis to accomplish this. Instead, you’re flexing the muscles that surround the base of your penis — your pelvic floor muscles. “These muscles create a ‘floor’ between your tailbone and your pubic bone,” says Brahmbhatt. “They support your prostate, bladder, seminal vesicles, bowel and rectum. They help you control urination and defecation, and in this case, they play a role in sexual function.”
In other words, according to Brahmbhatt, it’s not a penis muscle but rather a penis-adjacent muscle. “The ischiocavernosus muscle is a muscle just below the surface of the perineum (less formally known as your taint) that helps flex your anus, and in males, stabilize the erect penis.”
But what about once it’s inside? Does the flexing have any more, well, sexy purposes?
“There’s no functional reason beyond having the needed mobility to penetrate during sex when erect,” says Brahmbhatt.
Keep in mind that if you’re the type of guy who considers this penis-flexor to be your “finishing move” (your penis de resistance as it were), flexing your penis too often isn’t a good idea, especially if it’s notably curved. “I don’t recommend men flex and bend their penis, because over-bending can cause cracks or scars in the tissue, which could put you at risk or abnormal curvature (a.k.a. Peyronie’s disease),” say Brahmbhatt, referring to an unpleasant condition that can make it difficult to get or maintain an erection.
So much for penis exercises making your penis bigger.