Short vs. long? Weak vs. strong? Pelvic floor dysfunction explained.
Updated: May 21, 2019
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).
If the muscle is not at its ideal length (either too long OR too short) binding sites will be too far or too close to connect with therefore making fewer connections (e.g. caterpillar legs) and will diminish the effectiveness of its force (i.e. strength).
In looking at the strength of a muscle, which is "the ability of a muscle group to develop maximal contractile force against a resistance in a single contraction", can you now see how EITHER long OR short pelvic floor muscles can contribute to a lack of strength? The right graph below illustrates is perfectly. Muscle "tension" (in this case meaning strength) is maximal when muscle length is somewhere in the middle.
In relation to urinary incontinence, pelvic floor muscle length (either short or long) can contribute to a "weakness" in these muscles reducing the function and contraction of the pelvic floor to help lift bladder neck to maintain continence under loads, pressure, and movement. This is important in that pelvic floor strengthening exercises (i.e. kegels, vaginal weights, etc.) are not for everyone with incontinence. It may make things worse if you are tight.
While this post focused on muscle length versus strength, there are many other possible contributing factors to urinary incontinence including myofascial restrictions, poor behavioural strategies, altered core control strategies and coordination with other core muscles, altered breathing and pressure systems, neural influences, pelvic organ prolapse, and more). It is also important to note that this post is discussing issues more related to stress urinary incontinence. There are also urge and mixed urinary incontinence that are contributed to more so by some of the other contributing factors rather than length.
When in doubt or for some guidance, consult your local women's health and pelvic floor physiotherapists for an assessment to determine which you are (short or long) and if it is even an issue with your pelvic floor and not one of the many other possibilities elsewhere.
Remember: It is common, but NOT normal. There is hope and treatment for these pelvic floor issues and you are not alone:)
Photo credit: www.imgkid.com
Photo credit: http://nicktumminello.com
Disclaimer - Everything shared is for informative purposes only. It is not intended for assessment, diagnosis or treatment purposes. If you feel there needs to be further investigation, please seek out a qualified health care professional for a proper assessment.