Short vs. long? Weak vs. strong? Pelvic floor dysfunction explained.

A common myth about pelvic floor dysfunction (in relation to urinary incontinence) is that "If I leak, I must be weak"... AND pelvic floor muscles are long and need to be strengthen with kegels. While this may be the case for some, it is not so for everyone. A lot of the time women leak because of increased tension in the pelvic floor (or because there is something in the way - i.e. pelvic organ prolapse; this will be looked at in a different post). I think a lot of the confusion comes from the idea that weakness means less tension or longer/ stretched pelvic floor muscles. This is not always true. To explain this, we need to get into the physiology of muscles (the science nerd in me is getting excited!). But first, what and where

is the pelvic floor?

The pelvic floor is the group of muscles and connective tissue that sit at the bottom of the pelvic basin providing support for the internal organs, controlling elimination of bladder and bowels, influencing sexual sensation and muscular action, as well as providing a pumping action for the lymphatic system. The pelvic floor is also one of the four key anticipatory core muscles, working in concert with the respiratory diaphragm (main muscle of breathing), transverse abdominis (deepest abdominal muscle), and multifidis (small spinal stabilizers).



Like all voluntary muscles in the body (e.g. muscles we control to create movement like the biceps, triceps, glutes, quads, etc.), the pelvic floor muscles contract and relax. While they can be voluntarily contracted (e.g. kegels) they also tighten and release with the ebb and flow of our breath and should reflexively contract with increased abdominal pressure.

Its prime movement when contracting (i.e. shortening) is to flex/ tuck the tailbone forward toward the pubic bone, as well as lifting the bladder neck (urethra) to close it off to prevent leaking under loads (e.g. coughing, sneezing, laughing, jumping, lifting, etc.). When it relaxes, it allows for opening of the sphincters that control the bladder and bowels to eliminate.

Now that we know where and what the pelvic floor is and does, how does muscle length relate to strength (i.e. function)?

First, let's break down how muscles work. Muscles are made up of numerous fibers that divide smaller and smaller to the sarcomeres where the contraction (muscle fibers shorten) and relaxation (muscle fibers lengthen) of the muscle takes place. I like to imagine them like two caterpillars faced belly to belly with legs overlapping. These legs (myosin heads) need to be ideally lined up in order to connect with the binding sites to contract and do its work (or with the caterpillar, feet need to be able to reach one another to permit advancement).