Five recommendations for a happier pelvic floor
The pelvis evolved throughout tens of thousands of years of bipedal behaviour in humans on earth, and nature shaped our pelvis to be the impressive part of the body that it is. No part of the body is perfect; where there are strengths there are also vulnerabilities. For example, our stomachs and abdominal viscera would be better protected if we had ribs all the way down our trunk, but that would put a serious damper on our ability to be pregnant or even eat. So nature made a trade-off. Ribs are a solution to protect lungs/heart without making a heavy solid bone which would not be able to move. So we can move a bit, protect a bit, and not be burdened by excess weight. It's a best case scenario.
When it comes to the pelvis, there is a hole in the bottom. This large gap is filled by muscle(s) called the pelvic floor. This hole is great when it comes to the biological functions of the pelvis - letting things in and out, at the appropriate times, is a joy when it's working well and a real pita when it's not. The muscles of the pelvic floor support the contents of the pelvis and the weight of those contents can change with a full bladder, bowel, a pregnancy, and even things like if you are running versus walking.
The pelvic bones have joints that can move a little but not a lot (with the exception of the hip joints, which connect our legs to the pelvis). Most of us think of joints in terms of muscles moving bones. So there's a lot of controversy over how much the sacroiliac joint can move for example. But instead of thinking of how these joints move, I like to consider how they are moved, from forces coming from above and below them. The sacroiliac joints and the pubic symphysis are heavily reinforced with some of the strongest ligaments in the body. You have to ask yourself why would that be the case? Could it be that they are like that trade-off between some mobility for the occasional (relatively speaking) pregnancy and ability to squat to defecate, and serious stability to withstand the forces of walking, running etc.?
The sacrum is like a key in a stone arch. Viewed from above, it's wider at the top and narrows at the bottom (ending in the tailbone). This means the sacrum can withstand the weight of the trunk, with the last vertebra of the spine sitting on the top of the sacrum, because this wedge shape allows it to be a "self locking mechanism." The forces coming from the ground are channeled up the leg bones and through the neck/head of the femur to the pelvis, and then through the front rim of the pelvis to the pubic symphysis (PS) where it meets an equal force coming from the opposite side, balancing the forces. This is if you are standing still. If you walk you have forces from one leg and then the other, so there are shear forces created at the pubic symphysis.
Did you know: One of the ligaments of the pubic symphasis is created when tissues from multiple muscles coming from multiple directions meet and interweave to create this strong defence against too much motion, which would literally render us unable to walk. These muscles include abdominal muscles; rectus abdominus and external obliques (plus pyramidalis), and inner thigh muscles; gracilis and adductor longus.
As I said above, the pelvis evolved over eons of walking humans. But what do most humans do now? They sit! Pelvic floor dysfunction is a real problem in our sedentary population. Whether you have an organ prolapse, where some of the contents of the pelvis start to drop through the various exits of the pelvic floor, sacroiliac joint pain, lower back pain, hip pain, or incontinence, the variety and incidence of pelvic floor problems beset by our population is getting worse not better. You'd think with all our knowledge and research we'd have more answers. But for over 50 years our movement solution to PFD has been to strengthen by contracting the pelvic floor, aka "Kegel."
Maybe we should be looking at absent behaviour and not layering on a "strength bandage" as I call it. If you Kegel for years but still pee when you jump or laugh, is it because the pelvic floor just isn't strong enough? Perhaps, but it's not your fault. Increasing muscle strength doesn't always come from a shortening (concentric) contraction. A too-short muscle also is a weak muscle. The scenario we want for our pelvic floor is one where there are a variety of abundant loads from a variety of directions over long periods of time. What our pelvic floor experiences now in general is no loads at all for long times (sitting) and then a vigorous amount of a single type of load as we run on a treadmill, or cycle (creating tight hips and inner thighs). So you can exercise, but it doesn't cancel the fact that you need to walk, and often.
As well, some exercises that help load the pelvic floor in a healthy way are inner thigh stretches, abdominal twists, and squatting.
Here are my top five recommendations for a happier pelvis: