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  • Deborah Thomas BPT MCSP MAPPI Chartered Physio

What is the "Knack" and how can it prevent urinary leakage?

Updated: May 29, 2020

You may have been asked by your pelvic health physio to perform, or use ‘the knack’ manoeuvre, as a strategy to help prevent leakage of urine, or reduce the loads on your pelvic floor organs and muscles.


A Knack, in the dictionary, is defined as: ‘an acquired or natural skill at doing something’, and in the pelvic health world, we mean to acquire a skill to help counter a sudden increase in intra-abdominal pressure. This is a strong, voluntary, short, pelvic floor contraction, which we use just prior to and then during occasions such as a cough, sneeze, or lifting – and it provides counter pressure to the pressure coming from above, to help keep the bladder neck closed, and therefore to prevent loss of urine. This is a skill that requires coordination and practice. Several factors contribute to its success, such as the strength of the muscles, the

timing of the contraction and how the muscles are used. The most important thing though – is to remember to relax the pelvic floor muscles afterwards.


So, lets investigate what intra-abdominal pressure is, what is stress urinary incontinence and what is the science behind ‘the knack’ manoeuvre.



In our body, several areas can operate as ‘chambers of pressure’ and this helps our normal functions, for example the chest cavity, the abdominal cavity, and the pelvic cavity. The constant monitoring and adjusting of the pressures in these helps our breathing, digestive and lymphatic systems operate normally and effectively. The term ‘inra–abdominal’ pressures, refers to the pressure inside the abdominal cavity, which is the area between our Diaphragm – the main breathing muscle, above, and the pelvic floor muscles, at the bottom of the pelvis, below. The side walls of this cavity are formed by the abdominal muscles, back and waist muscles and bony structures. You might imagine this as a canister, where the walls, roof and floor are flexible and responsive. This cavity has a very smart design, with several openings in it, and valves and sphincters to control what can go in or out, as well as help control the pressures inside it.


The movement of our Diaphragm is constant, but can change depending on our activity level, posture, any joint or spinal restrictions and habits. When we breath-hold, cough, sneeze or lift, this causes a downward pressure of the roof of this ‘canister’, and the pelvic floor muscles, as well as the abdominal muscles, coordinate their activity to adjust to this

change in pressure. We find, however, that in some instances, this coordinated response isn’t as effective as it can be; possibly, the pelvic floor muscles don’t respond in time, or don’t provide enough of a close and lift action to provide the counter pressure, and this can cause a total effect of a stronger downward pressure on the bladder, urethra and pelvic floor muscles, and therefor loss of urine. This is termed Stress Urinary Incontinence or SUI.

SUI can be a result of several factors: Pelvic floor muscles that are too tight, too weak, uncoordinated or lack motor control appropriate for the task. This is why it is important to book an appointment with a pelvic health Physiotherapist, to establish the cause of the incontinence.


The Knack itself is not a pelvic floor exercise, or a ‘Kegel’. It is not designed to ‘strengthen’ the muscles. As noted above, it may be that the muscles are too tight or over-working, and therefor this is not a strengthening regime. Although we are using the same muscles, the goals are different. The research looking into this technique was carried out by JM Miller et all in 2008: Clarification and Confirmation of the Effect of Volitional Pelvic Floor Muscle Contraction to Preempt Urine Loss (The Knack Maneuver) in Stress Incontinent Women.

In this study, pregnant on non-pregnant women participated, and they coughed, in standing, with a full bladder. Within one week of learning how to use the knack (instructed to contract their pelvic floor muscles one second before they coughed), they leaked 98.2% less with a medium cough and 73.3% less with a deep cough.


The skill, coordination and timing of the knack is what created the difference here, not the strength of the pelvic floor muscles. Therefore, to learn the skill, confirm its effectiveness and learn the timing, it is helpful to undergo an assessment and evaluation by a pelvic health physiotherapist.


We know from research, (Activity of Deep and Superficial Pelvic Floor Muscles in Women in Response to Different Verbal Instructions: A Preliminary Investigation Using a Novel Electromyography Electrode, R. Aljuraifani 2019) and (What is the most effective verbal instruction for correctly contracting the pelvic floor muscles? Ben Ami N et al 2018) that verbal cueing alone, does not produce an effective pelvic floor contraction: we may get a

contraction of the superficial layer instead of the deeper layer, and the coordination within the deeper layer may not be accurate.


Cough pressures vary significantly; it may be a serve in Tennis or Hockey, lifting a baby or toddler, or doing housework that you struggle with.


As part of a holistic therapy approach, your pelvic health assessment and treatment will look into the functions of the diaphragm, how to use diaphragmatic breathing to manage the intra-abdominal pressure effectively for your goals.


This post is intended to give you a summary on this topic and how to perform the Knack.


You now understand more about how we manage pressure and how a pelvic health physio can help you reduce the symptoms of SUI, by investigating the underlying causes, establishing a bespoke treatment plan to address your issues using the knack and many other techniques.



If you would like to come and see Deborah, book online with this link:


References:

1. R. Aljuraifani et al 2019: Activity of Deep and Superficial Pelvic Floor Muscles in Women in Response to Different Verbal Instructions: A Preliminary Investigation Using a Novel Electromyography Electrode.

https://doi.org/10.1016/j.jsxm.2019.02.008

2. R. Stafford et al 2015: Pattern of Activation of Pelvic Floor Muscles in Men Differs With Verbal Instructions. Neurourology and Urodynamics DOI 10.1002/nau

3. Ben Ami N et al 2018: What is the most effective verbal instruction for correctly contracting the pelvic floor muscles?

https://doi.org/10.1002/nau.23810

4. Miller JM et al 1998: Clarification and Confirmation of the Effect of Volitional Pelvic Floor Muscle Contraction to Preempt Urine Loss (The Knack Maneuver) in Stress Incontinent Women

https://dx.doi.org/10.1007%2Fs00192-007-0525-3

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