Lior Lowenstein & Ilan Gruenwald & Irena Gartman & Yoram Vardi
Received: 7 October 2009 / Accepted: 2 December 2009 / Published online: 20 January 2010 # The International Urogynecological Association 2010
Abstract
Introduction and hypothesis This study aims to evaluate the association between pelvic floor muscle (PFM) strength and sexual functioning.
Methods Retrospective chart review of consecutive all women who were referred with a primary complaint of sexual dysfunction. Women underwent standardized clini-cal evaluation including pelvic muscle strength which was ranked from 0 (weak) to 2 (strong). The duration of pelvic muscle contraction was also recorded in seconds. Sexual function was evaluated by using a validated questionnaire, the Female Sexual Function Index (FSFI).
Results One hundred seventy-six women with a mean age of 37±11 years were included. Women with strong or moderate PFM scored significantly higher on the FSFI orgasmic and arousal domains than women with weak PFM (5.4±0.8 vs. 2.8±0.8, and 3.9±0.5 vs. 1.7±0.24, respec-tively; P<0.001). The duration of PFM contraction was correlated with FSFI orgasmic domain and sexual arousal (r=0.26, P<0.001; r=0.32, P<0.0001, respectively). Conclusions Our findings suggest that both the orgasm and arousal function are related to better PFM function.
L. Lowenstein (*)
Department of Obstetrics and Gynecology, Rambam Medical Center,
9 Ha’Aliya Street,
Haifa 31096, Israel
e-mail: [email protected]
L. Lowenstein : I. Gruenwald : I. Gartman : Y. Vardi Neuro-Urology Unit, Rambam Health Care Campus, Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology,
Haifa, Israel
Keywords
Duration of muscle contraction . Muscle strength . Pelvic floor muscles . Sexual function
Abbreviations
PFM – pelvic floor muscle
PFMT – pelvic floor muscle training
MVC – maximum voluntary contraction
FSFI – Female Sexual Function Index
SD – sexual dysfunction
Introduction
Pelvic floor muscle (PFM) strength is believed to be related to the amount of sensation a woman feels during vaginal intercourse and for the strength of grip felt by her partner [1].
The PFM, in particular the pubococcygeus and iliococ- cygeus muscle, are responsible for the involuntary rhythmic contractions during orgasm [2]. At the time of sexual stimulation, sensory impulses travel to the sacral cord through the pudendal nerve and in response, blood is directed to the genital organs, through the control of efferent fibers which innervates the vagina, uterus, and PFM [2]. In consequence to the increase in peripheral blood circulation, the vulva and the vagina become swollen (tumescent) and the glands which are connected to the reproductive tract increase their secretions during sexual arousal. With continued uninterrupted stimu- lation, the physiologic changes which characterize sexual arousal may progress and build up until they approach a maximum point. Once reaching to this point the PFMs are getting tensed, they rise to a new maximum tension which is maintained momentarily and then followed by instantaneous- ly release of all tension. That reflex, also known as orgasm, which is followed by PFMs spasm or convulsions, [2] between five and 15 times at 0.8-s intervals. PFM contraction is known to play an important role in the female orgasmic response [2]. Graber et al. demonstrated a significant decrease in the strength of pubococcygeus muscle contractions in anorgasmic women compared with orgasmic women [1].
The results of this study suggest that the pubococcygeus muscle plays an important role in the pathophysiology of female anorgasm [1]. This study was followed by two interventional studies, which demonstrated that women with weak muscles who receive PFM training (PFMT) to strength- en their muscles in this region, reported a positive effect on their sexual life [3–5]. These findings, suggesting that improved sexual function might be related to stronger PFMs.
Other supportive data for the role of PFM strength on sexual function was obtained by Messe et al., who evaluated the effect of vaginal musculature contractions (Kegel exer- cises) on sexual arousal. In this study, following only 1 week of Kegel exercise, women had a significant improvement in both subjective and objective measures of sexual arousal [6].
The direct effect of PFM on sexual function is probably not just related to the strength of muscle contraction at the time of orgasm [3–5]. It is hypothesized that pelvic floor muscles control the anatomical position of clitoral erectile portion, with consequences to sexual stimulation [7]. This theory was investigated by Foldes et al. who used an ultrasound testing for the evaluation of the anatomy of the pelvic floor. The authors demonstrated that during contrac- tion of the ischiocavernous and bulbocavernous muscles, the clitoral bodies descend and come close to the distal portion of the anterior vaginal wall [8].
Currently, there is scarce data in the literature regarding the association between PFM strength and sexual function [3–6, 9, 10]. The aim of the current study was to evaluate the association between PFM strength and the different domains of sexual functioning.
Methods
This is a retrospective chart review study. After obtaining an institutional review board approval, we abstracted clinical and demographic data from consecutive charts of all women referred to our tertiary urogynecology clinic between October 1999 to January 2009, with a primary complaint of sexual dysfunction (SD). All women under- went a standardized clinical evaluation including the evaluation of pelvic muscle strength and gynecological examination. Maximum voluntary contraction of pelvic muscles was evaluated by one gynecologist (GI). Digital vaginal evaluation was performed with patients in a supine position with a pillow under their head, with their knees straight, and legs abducted. After positioning the investigator’s index finger into the distal part of the vagina, subjects were asked to contract their PFM. Women were instructed to lift their PFMs in an upward and inward fashion by squeezing their muscles around the examiners’ finger. The established constriction and elevation of the vaginal wall and the strength of PFM were ranked from 0 (weak) to 2 (strong). Weak PFMs strength was defined, when PFM contraction could not be detected or in cases of a very weak contraction which was difficult to detect by the examining finger. Medium PFMs strength was defined when PFM contraction, was well perceived but could not be maintained against moderate opposition from the examiner’s fingers. Strong PFMs was defined in cases of maximum contraction with strong resistance to opposition. For evaluation of the duration of PFM contraction, women were instructed to contract their PFMs as hard as they can for the longest possible period. The duration of PFM contraction was recorded by the examiner in seconds. The existence of vaginal mucosal atrophy (yes/no) was determined based on clinical evaluation. Sexual function was evaluated by using a validated questionnaire the Female Sexual Function Index (FSFI) [11]. The FSFI is a 19-item self-reported measure of female sexual function that provides scores in six domains. The instrument measures desire, arousal, lubrication, orgasm, satisfaction, and pain. Each domain is scored on a scale of 0–6, with higher scores indicating better function. For each six domains a score was calculated and the total score was obtained by adding the six domain scores. The total score range was 2–36 [11].
Statistical analysis
Independent Student’s t test was used to compare continuous variables between independent groups. For purpose of analysis we combined the group of patients with strong and moderate PFM strength to one category. Pearson’s correlation was used to evaluate the association between independent groups with continuous variables. Multivariate linear regression was used to identify independent factors associated with orgasmic and arousal scores. In the final model, we included age, menopause, parity, vaginal atrophy, muscle strength, diabetes, duration of PFM contractions, and urinary incontinence. All tests were considered significant at the 0.05 level.
Results
One hundred seventy-six women with a mean age of 37± 11 years were included in our study. Participants referred to our clinic for the following primary sexual dysfunction complaints: 47% low libido, 40% anorgasm, 8% dyspar- eunia, and 5% other, mean FSFI score was 14±7. Ten percent (18) of women were diagnosed to have strong muscle contraction, 41% (100) had moderate muscle contraction, and 41% (76) had weak pelvic muscle contraction. There were no statistical significant differences between women with strong or moderate and weak pelvic muscle strength with regard to demographic and medical history (Tables 1 and 2). Women with strong or moderate PFM contractions scored significantly higher on both the orgasmic and the arousal domains of the FSFI compared with women with weak PFM contraction (5.4±0.8 vs. 2.8±0.6 and 3.9±0.5 vs. 1.7±0.24, respectively; P<0.001). There were no significant differences in all other FSFI domains between patients with strong and moderate vs. weak PFMs (Table 3). The mean duration of PFM contraction was 8.7± 9.3 s. Interestingly, there was a moderate correlation between the duration of PFM contraction and FSFI orgasmic and sexual arousal domains (r=0.26, P<0.001; r=0.32, p< 0.0001, respectively).
Multivariate linear regression demonstrated that the duration of PFM contraction was the only independent factor associated with orgasmic and arousal scores (β=0.24, P<0.002 and β=0.35, P<0.0001, respectively); for every 1 s increase in the duration of muscle contraction there was a 0.24 U increase on the FSFI orgasmic domain score and 0.35 U increase on the FSFI arousal domain score.
Discussion
Our study suggests that PFM strength is associated with sexual function. More specifically, it was found that both orgasm and arousal functions are associated with PFM strength. The role of PFM contractions at the time of orgasm is well recognized [1, 3–5]. Yet there is not enough data to support the association of PFM strength with sexual function. More than 50 years ago, Kegel [9] identified for the first time, that PFM weakness can result in sexual dysfunction [9]. It was hypothesized that at the time of intercourse, sexual pleasure is enhanced by the contractions of the pubococcygeous and iliococcygeus muscles [10]. Our results demonstrated that women with stronger PFM scored higher on both orgasm and arousal domains of the FSFI
support this hypothesis. These findings are also supported by Graber et al. who demonstrated that weakness of PFM provide insufficient contractions necessary for vaginal friction and blood flow, and consequently resulting in inhibiting of the orgasmic potential [1]. Hence, it is reasonable to propose that strengthening weak PFMs may positively affect sexual function.
Previous studies which evaluated the role of PFMT on sexual function demonstrated that in women with urinary incontinence who received pelvic floor rehabilitation and consequently had strengthening of the muscles in this region noticed a positive effect on their sexual life [3, 5]. This study had a selective population, and therefore, it is not clear whether the improvement in sexual function was due to PFM strengthening, or as a consequence of improvement in urinary incontinence.
Sexual dysfunction is multifactorial and its etiology may be a result of physical, social, and psychological factors. SD is categorized according to commonly accepted domains: orgasmic, libido, arousal, satisfaction, pain, and vaginal lubrication. To the best of knowledge our study is the first to evaluate the correlation between PFM strength with the different FSFI domain. Since the orgasm phase involves PFM contraction, the correlation between the strength of PFM and orgasm quality is colloquially accepted. Our findings regarding the correlation between sexual arousal and PFM strength is also supported in the literature. A previous study by Shafik evaluated the direct effect of PFMT on the different domains of sexual functioning, and demonstrated that strengthening of PFM resulted in improvement of sexual desire, performance during coitus, and achievement of orgasm [10]. These findings may probably be explained by the fact that PFMT results in changes of muscle morphology by increasing cross-sectional diameter. PFMT may also improve neuro- muscular function by increasing the number of activated motor neurons and their excitation frequency [12]. These changes may affect both pelvic muscle contraction and sexual arousals [13]. Exercise may also affect sexual function by improving circulation to the genital organ, mainly to the PFM, which is responsible for engorging the clitoris during the arousal phase.
The limitation of our study is using a grading system for the evaluation of pelvic muscle strength with a different ranking scale from the modified Oxford scale [14]. This limitation may be overcome by the fact that muscle strength was evaluated by using two different parameters; (1) a subjective evaluation of PFM contraction by one examiner and (2) an objective measure of the endurance of PFM contractions [15]. The direct association of orgasmic and arousal scores, with the endurance testing of PFM contrac- tion, support the significance of pelvic muscle strength in sexual function. PFM tonus was not measured in our study. Though currently there is no standardized tool for the PFM tonus measurement, it can affect sexual function, as is often recognized in a patient with pelvic pain [10]. In addition, our study may be possibly biased by its retrospective character and its selective population, as being a referral clinic, the diversity of the incidence of womens’ primary complaint may differ from that of the general population. Future studies are needed to evaluate if these correlations are maintained in women without sexual dysfunction.
Conclusions
Women with greater PFM strength reported higher scores on the FSFI orgasmic and arousal domain and have an improved sex function. Future comparative effectiveness trials are needed to evaluate the role of PFM exercise in females on sexual function and orgasm.
Conflicts of interest None.
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