Breathing with the pelvic floor?

ISSN 0937-3462, Volume 21, Number 4

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Int Urogynecol J (2010) 21:475–481 DOI 10.1007/s00192-009-1060-1

Author's personal copy

ORIGINAL ARTICLE

Breathing with the pelvic floor? Correlation of pelvic floor muscle function and expiratory flows in healthy young nulliparous women Helena Talasz & Markus Kofler & Elisabeth Kalchschmid & Michael Pretterklieber & Monika Lechleitner

Received: 12 August 2009 / Accepted: 11 November 2009 / Published online: 8 December 2009 # The International Urogynecological Association 2009

Abstract Introduction and hypothesis The aim of this cross-sectional study was to determine correlations between pelvic floor muscle (PFM) function and expiratory function in healthy young nulliparous women. Methods In 40 volunteers, PFM function was assessed by vaginal palpation. Forced expiration patterns were evaluated visually and by palpation of the suprapubic insertion region of the anterolateral abdominal muscles. Forced vital capacity (FVC) and forced expiratory flows (FEF) were determined by spirometry. Results Incremental positive correlation was found between voluntary PFM contraction strength and forced expiratory flow at 25%, 50% and 75% (FEF25%, FEF50%, FEF75%) of the FVC, respectively. Positive correlation was also found

H. Talasz (*) : M. Lechleitner Department of Internal Medicine, Hochzirl Hospital, Hochzirl 1, 6170 Zirl, Austria e-mail: [email protected] M. Kofler Department of Neurology, Hochzirl Hospital, Hochzirl 1, 6170 Zirl, Austria

between PFM contraction strength and forced expired volume in 1 s (FEV1). No correlation was found between PFM contraction strength and FVC or peak expiratory flow (PEF). Conclusions Despite some limitations of this study, the observed correlation between PFM contraction strength and forced expiratory flows may serve as theoretical background for a potential role of coordinated abdominal and PFM training in diseases with expiratory flow limitations. Keywords Abdominal core . Anterolateral abdominal muscles . Diaphragm . Expiratory flows . Pelvic floor muscles Abbreviations FEF FEF25%, FEF50%, FEF75% FEV1 FVC IAP PEF PFM %RV

Forced expiratory flows Forced expiratory flow at 25%, 50% and 75% of the forced vital capacity Forced expired volume in one second Forced vital capacity Intra-abdominal pressure Peak expiratory flow Pelvic floor muscles Percent of the reference value

Introduction E. Kalchschmid Training Centre West of Health Care Professionals, Innrain 98, 6020 Innsbruck, Austria M. Pretterklieber Center of Anatomy and Cell Biology, Department of Applied Anatomy, Medical University of Vienna, Waehringerstrasse 13, 1090 Vienna, Austria

The term “pelvic floor muscles” (PFM) refers to the plate of different muscular layers extending from the pubic symphysis along the sidewalls of the os ilium towards the coccyx [1]. These different muscles have different fibre directions; however, the only known voluntary contraction of the PFM is a mass contraction, which results in a cranioventral movement of the perineum and the pelvic organs,


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forcing of the abdominal contents induced by the inspiratory manoeuvre [2, 12, 14]. However, more recent scientific findings indicate that the PFM contract eccentrically during inspiration and concentrically contract together with the abdominal muscles during forced expiratory manoeuvres and coughing, thereby reducing the volume of the abdominal cavity and increasing the IAP, which forces the diaphragm upwards and enhances expiratory effort [9, 11, 15–17] (Fig. 1). There is growing evidence for differential involvement of the four anterolateral abdominal muscles (rectus abdominis, obliquus externus, obliquus internus and transversus abdominis muscles) in expiratory function [18, 19]. Hodges et al. [11] reported that the PFM increase their activity during inspiration but have a greater increase during expiration. Because of the postulated synergistic coactivation of PFM and anterolateral abdominal muscles, we hypothesise that expiratory manoeuvres are associated with a correlation of PFM function (as clinically assessed) and expiratory parameters (as determined by spirometry).

and in an inward lift and squeeze around urethra, vagina and rectum [1–4]. According to the Pelvic Floor Clinical Assessment Group of the International Continence Society, normal PFM function is defined as “the ability to contract and relax PFM voluntarily and involuntarily”. The term “voluntary PFM contraction” denotes muscle contraction on demand. “Involuntary PFM contraction” refers to a muscle contraction that precedes a rise in intra-abdominal pressure (IAP), for example due to coughing, in order to prevent genital organ descensus and incontinence [1]. Two functions of the PFM are generally accepted: support of pelvic organs and contribution to closure mechanisms of urethra and anus [1, 3]. Recent findings, however, indicate that PFM do not work in isolation. Rather, they are considered to work in orchestrated synergies with other muscles surrounding the abdominal cavity, particularly anterolateral abdominal muscles and thoracic diaphragm [3, 5–11]. All these muscles together represent a muscular capsule, sometimes referred to as “abdominal canister” or “abdominal core” [3, 9, 10, 12] (Fig. 1). The “abdominal core” muscles are thought to both modulate and respond to changes in IAP [12, 13]. They also provide trunk stability during changes in posture, walking, talking, deep breathing, coughing and limb movements [6, 8, 10, 11]. Different opinions have been put forward about the role of the “abdominal core” muscles in connection with breathing patterns. For many years, it has been assumed that IAP “acts like a balloon in front of the spine that pushes down on the pelvic floor and up on the diaphragm to cause the spine to extend and thus prevent it from being flexed during lifting” [12]. Some authors argue that both PFM and anterolateral abdominal muscles should contract during inspiration, thereby creating a counter-pressure against the downward

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Int Urogynecol J (2010) 21:475–481

Subjects and methods We performed a cross-sectional study in order to determine correlations between PFM and expiratory function in healthy young women, applying the model of orchestrated synergy between the different muscle groups surrounding the abdominal cavity (deep anterolateral abdominal muscles, PFM and diaphragm in particular). The study was approved by the ethical committee of Innsbruck Medical University, Austria, and was carried out in Hochzirl Hospital, a nearby general hospital with departments of Internal and Geriatric Medicine and Neurology.

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Fig. 1 Theoretical model to demonstrate the movement of the “abdominal core” muscle groups during inspiration, forced expiration or coughing (D diaphragm, PF pelvic floor, AM anterolateral abdominal muscles, DAM deep anterolateral abdominal muscles, i.e. obliquus internus and transversus abdominis muscles). a During inspiration, the diaphragm concentrically contracts and moves downwards. Abdominal muscles and PFM relax. b During forced

expiration and coughing, anterolateral abdominal muscles contract and force the relaxing diaphragm upwards. Without PFM and deep abdominal muscle, co-contraction-increased intra-abdominal pressure may lead to PF descent and bulging out of the lower abdominal wall. c During forced expiration and coughing, PFM and deep abdominal muscles co-contraction protect the pelvic floor against descent and the lower abdominal wall from bulging out



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Forty volunteers, with mean age 25±5 years, ranging between 18 and 35 years old, not pregnant and in good general health, were included after granting written informed consent. Twenty-eight women (70%) were students or employees in a medical health profession, two (5%) were teachers and ten (25%) office workers. Most women demonstrated a high level of health consciousness; 11 (27.5%) had requested information about PFM function in the past for their own interest. The women were evaluated by applying a non-validated questionnaire about medical disorders, smoking habits and sporting activities. Body mass index was calculated by measuring the women's height and body weight. The participants' characteristics are presented in Table 1. All subjects underwent clinical assessment of PFM function and laboratory testing of expiratory function by spirometry.

Table 2 Graduation of the maximum pelvic floor muscle contraction according to the six-point Oxford grading scale modified by Laycock (2002)

Assessment of PFM function

Testing of respiratory function by spirometry

PFM function was assessed according to the International Continence Society [1] in supine position by digital vaginal palpation. The examination was carried out by a female physician with extensive experience in female PFM assessment and re-education. Subjects were asked to contract, lift inward and squeeze PFM, to cough and to “forcefully exhale without changing position”. Constriction and elevation of the vaginal wall and strength of PFM contractions were graded according to the six-point Oxford grading scale by Laycock (Table 2) [20]. PFM function was assessed during muscle contractions on demand, during coughing and at the beginning of a forced expiration. Co-

Spirometry was carried out according to the American Thoracic Society/European Respiratory Society (ATS/ERS) criteria 2005 [21, 22] on a portable flow/volume-sensing turbine spirometer with real-time graphic display (Micro Medical SuperSpiro, Kent, UK). In a sitting position, participants were instructed to exhale completely, then to take the deepest breath possible, insert the breathing tube into the mouth, seal the lips around the mouthpiece and start a forceful and complete exhalation. Forced vital capacity (FVC), defined as the total amount of exhaled air (expressed in litres (l)), forced expired volume in one second (FEV1), peak expiratory flow (PEF), and forced expiratory flows at 25%, 50% and 75% of the exhaled FVC (FEF25%, FEF50%, FEF75%, respectively)—all expressed in litres per second (l/s)—were recorded. The manoeuvres were repeated two or three times with accepted FVC and FEV1 differences 0.044

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Fig. 3 Correlation between PFM contraction strength (Oxford scale score 0–5) and FEF25%, FEF50%, FEF75%—expressed in percent of the reference value (%RV)—in the whole group of 40 women (n=40). The Pearson's test was used for statistical analysis

contraction; 16 women performed neither PFM nor anterolateral abdominal muscle contraction. However, due to the limitations of the clinical evaluation technique, no statistical analysis was performed to determine any possible correlation with the women's voluntary PFM contraction strength. Subjects' age, body mass index, amount of sporting activities, smoking habits and reported pulmonary symptoms (such as dyspnoea, chronic cough and hyperventilation) did not show any correlation with voluntary PFM contraction strength (graded according to the Oxford grading scale), or FVC (expressed in l, or in %RV), or FEF (expressed in l/s, or in %RV). Notably, none of the women was aware of synergies between PFM and abdominal muscles or about the potential role of PFM in breathing or coughing patterns.

Discussion The main findings of this study are: 1. As hypothesised, during forced expiration, expiratory flows were positively and incrementally correlated with PFM function, i.e. women with stronger voluntary PFM contractions were able to exhale more efficiently, particularly during the later phases of expiration. 2. A high percentage of young women were unable either to perform a voluntary PFM contraction on demand or an involuntary PFM contraction during coughing and at the beginning of a forced expiration. Furthermore, they were unaware of the role of PFM and abdominal muscles in breathing and coughing patterns. Despite a high level of instrumental diagnostic and therapeutic methods that deal with the female pelvic floor, a substantial lack of basic information still remains. Not only

did the study participants show poor awareness about PFM functions, but also the literature has little scientific data regarding potential synergies between PFM, abdominal muscles and the thoracic diaphragm in connection with breathing and coughing. During forced expiration patterns, contraction of the abdominal muscles is known to play an important role in making expiration more rapid and more efficient. They pull down the ribcage and facilitate the upward movement of the diaphragm. Additionally, through an inward movement of the abdominal wall they increase the IAP which further forces the diaphragm upwards. On the contrary, respiratory muscle weakness is known to reduce FVC and PEF [22, 23]. The significance of mid- and end-expiratory flows (FEF25%, FEF50%, FEF75%) is not clearly defined in literature. Some authors suggest that they are only caused by elastic recoil properties of the lung and resistive properties of the airways [15, 23]. On the other hand, it is also known that respiratory muscle weakness may produce a sharp fall in end-expiratory flows in forced spirometry manoeuvres [22]. In the present study, coughing and forced expiration were defined as reflexively or voluntarily initiated explosive expiration manoeuvres, using the same diaphragmatic, abdominal, and PFM patterns, with the intention to powerfully expel previously inhaled air or contaminants from the lungs [17]. Well-functioning synergies of the “abdominal core” muscles during coughing as well as during other expiratory manoeuvres provide the physiological basis for directing the IAP towards the relaxing diaphragm. In order to explain the results of the present study, we propose a theoretical model based on physiological properties of the “abdominal core” muscles. A fast synchronous maximum contraction of all four anterolateral abdominal muscles during coughing [19] or at the beginning of a voluntary forced expiratory manoeuvre, may cause a rapid initial rise in IAP, and thus may

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influence PEF. The deep abdominal muscles (transversus abdominis and obliquus internus muscles), may therefore act as a type of “bellows” that increases IAP in a more persistent manner, thereby forcing the diaphragm upwards by a delayed synergistic contraction (Fig. 1). Bolser et al. showed, that graded expiratory threshold load elicited graded increases of EMG activity in these muscles [19]. Caudal fibres of both muscles insert into the pubic crest and —by forming a conjoined tendon—into the inguinal ligament [24], where their contraction may be felt by digital palpation in the suprapubic region as an inward movement of the lower abdominal wall [20]. There is evidence of functional co-activation of PFM and deep anterolateral abdominal muscles, particularly transversus abdominis and obliquus internus muscles [3, 6, 8]. Hence, an inadequate contraction of these muscles during a rapid rise in IAP may be responsible for the often observed bulging out of the lower abdominal wall and for the descent of the pelvic floor (Fig. 1). A stronger contraction of the abdominal wall muscles is known to be associated with a greater coordinated PFM response [8]. The present findings suggest also the converse: women with stronger voluntary PFM contractions are more likely to have efficient co-contractions of the deep abdominal muscles; consequently, they are also likely to exhale more efficiently, particularly during the midand end-phase of expiration. Notably, this is consistent with the notion that singers learn to exhale forcefully and to powerfully expel the air “from the deep abdominal space” [25]. Remarkably, those four women in this study who showed PFM and abdominal muscle co-contraction during coughing and at the beginning of a forced expiration had received intensive musical education in the past as singer or brass instrumentalist. Perhaps, they may also have used different inspiratory patterns, as they are likely to have received specific instruction in breathing techniques, including abdominal breathing with a large abdominal excursion during inspiration. It is possible that they used this pattern during the forced expiration manoeuvre. Intravaginal palpation and assessment of voluntary PFM contraction on demand by the Oxford grading scale is an easy and reliable method to evaluate PFM function. Correct PFM contraction can be assessed, and co-contractions of abdominal muscles are easily identified [4, 20]. Evaluation of involuntary PFM and abdominal muscle function by digital palpation in dynamic conditions is much more difficult and imprecise. Validity, inter-tester reliability and reproducibility of this method have not been tested yet. Therefore, in the present study no statistical analysis was applied to determine whether the presence of an involuntary PFM and anterolateral abdominal muscle contraction during coughing and at the beginning of a forced expiration depended on the women’s voluntary PFM contraction strength.


Another limitation of the present study is that participants do not represent a typical cross-section of the general population due to their young age, above-average medical knowledge, and high health consciousness. Their limited and insufficient knowledge, however, about PFM function and physiological breathing and coughing patterns may be explained by the general education in western civilization. The participants' posture may also have influenced the results, as supine and upright position exhibit different PFM and abdominal muscle activity at rest [26], which may affect the recruitment of these muscles in different exercises, during PFM assessment, and during spirometry. Unfortunately, when carrying out digital vaginal PFM palpation, presence or absence of a PFM contraction was not assessed during the whole period of forced expiration, but only at its beginning. In order to evaluate possible “abdominal core” muscle contractions occurring later in the course of expiration, it would have been important to assess PFM function during the whole expiration period, perhaps using electromyography. The present study reveals for the first time a positive correlation between PFM and expiratory function in young healthy women. Even though the underlying mechanisms are still hypothetical, we believe that the demonstrated correlation of PFM function and EF may foster clinical and therapeutic implications for the understanding and management of diseases with expiratory flow limitations. It might also serve as theoretical background for a potential role of combined PFM and abdominal muscle training in the treatment of respiratory diseases. Conflicts of interest None.

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