effect of variations in forced expiration effort.4

8/11/2019 Effect of Variations in Forced Expiration Effort.4

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ABSTRACTObjective: The purpose of this study was to investigate theeffect of variations in forced expiration effort on the auto-matic activation of pelvic oor (PF) muscles.Study Design: Quasiexperimental repeated measures.Background: The PF activates automatically, both squeez-ing and lifting, during times of increased intra-abdominalpressure for postural stability and continence. Expirationadditionally produces automatic activation of the PF mus-cles. No study to date has investigated the effects of forcedexpiration on PF displacement and squeeze pressure.Methods and Measures: A convenience sample of pre-menopausal, nulliparous, continent women was recruitedand instructed on 3 variations in forced expiration effort:(1) minimum; (2) moderate; and (3) maximum. Pelvic oorautomatic activation measurements were taken using peri-neometry (squeeze pressure) and transperineal ultrasoundimaging (PF displacement) during each type of expiration.Chi-square test was used to analyze the direction of PFdisplacement, and Friedman analysis by ranks was usedto analyze the magnitude of the squeeze pressure and PFdisplacement.Results: Data of 18 women, aged 24.8 2.5 years, wereanalyzed. There was a signicant difference in the vaginal

squeeze pressure ( P < .001) and magnitude of displace-ment in the horizontal plane ( P < .001) and the verticalplane ( P < .001) of the PF between the 3 variations of

INTRODUCTION

The pelvic oor (PF) is a dynamic and complexstructure that serves many functions, including pelvicorgan support, continence, respiration, and lumbo-pelvic postural stability. 1-3 A volitional contractionof the PF muscles displaces the PF cranially andventrally, closing the urethral opening and sup-porting the bladder neck from descending. 4-10 Thiscranial-ventral displacement with sphincteric closingforces supports continence. Successful rehabilitationfor individuals with stress and mixed urinary incon-tinence involves instruction and procient practiceof a volitional PF contraction that demonstratesthe proper cranial-ventral displacement and squeezepressure. 3 , 11

The PF muscles automatically activate duringrespiration, with greater activation during expirationthan during inspiration. 2 Moreover, PF displace-ment, measured by magnetic resonance imaging, hasbeen objectied during inspiration (caudal direction)and expiration (cranial direction). 12 The PF addi-tionally automatically activates during increases in

intra-abdominal pressure (IAP).13

,

14

This automaticactivation functions in a feedforward fashion to resistthe caudal pressure of the intra-abdomen, stabilizeposture, and support continence. 2 , 3 , 10 , 15

1 Clinical Musculoskeletal Research Laboratory, Centerfor Rehabilitation Research, Texas Tech University HealthSciences Center, Lubbock.2 Atlas Physical and Hand Therapy, Atlas Womens HealthPhysical Therapy, Eugene, Oregon.3 College of Pharmacy and Health Sciences, CampbellUniversity, Buies Creek, North Carolina.

The primary investigator supplied private funding.The authors declare no institutional funding or conicts ofinterest.DOI: 10.1097/JWH.0000000000000005

Effect of Variations in Forced ExpirationEffort on Pelvic Floor Activationin Asymptomatic Women

Lenore J. Kitani, PT, ScD1 Gail G. Apte, PT, ScD2 Gregory S. Dedrick, PT, ScD3 Phillip S. Sizer, PT, PhD1 Jean-Michel Brisme, PT, ScD1

expiration. Minimum effort of forced expiration createdthe most consistent PF displacement in a cranial-ventraldirection.Conclusions: Minimal forced expiration effort resulted inthe most consistent PF cranial-ventral displacement withvaginal squeeze pressure. These ndings provide basicscience information on PF activation applicable to PF train-ing programs.Key Words: pelvic oor , rehabilitation , respiration


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Copyright 2014 Section on Womens Health, American Physical Therapy Association. Unauthorized reproduction of this ar ticle is prohibited.

Automatic PF activation patterns have beenmeasured with electromyography (EMG). 2 , 15 , 16Electromyography, however, does not quantify thefunctional squeezing pressure of the PF, nor doesit qualify the direction of PF displacement duringmuscle activation. Pelvic oor closing forces are mea-sured as a vaginal squeeze pressure, with manometryor perineometry demonstrating reliability appropriatefor clinical research. 17-21

Ultrasound imaging (USI) has gained popularityas a relatively inexpensive and clinically accessiblemethod for assessing the PF muscle activity and posi-tion. 22-24 It provides information on PF displacement,represented by changes in the position of the bladderbase (transabdominal USI) or bladder neck (trans-perineal [TP] USI) during a Valsalva maneuver 25-27or volitional PF contraction. 22 , 23 , 25 , 28-30 Together,squeeze pressure and displacement are measures thatoffer qualitative and quantitative information on thefunctional aspects of PF activation. 6,7,9 , 31-36

In PF rehabilitation programs, a volitional contrac-tion of the PF muscles can be taught with expiration,based on the understanding that expiration facilitatesPF muscle activation and cranial displacement. Amore forceful expiration results in even greater cra-nial displacement than quiet expiration, as well asgreater PF EMG activity. 12 , 13 However, forced expira-tion additionally results in increases in IAP with max-imum forced expiration against a closed glottis, or

Valsalva maneuver, resulting in PF descent and pos-sible disruption of continence mechanisms. 3 , 13 , 25-27 , 37Although forced expiration facilitates PF activation, itis still unknown how the PF automatically respondsto gradations of forced expirations. Specically, noinvestigator to date has measured automatic activa-tion of the PF muscles as squeeze pressure and PFdisplacement using TP USI to a standardized varia-tion in forced expiration effort. It was hypothesizedthat minimum and moderate forced expiration effortswould result in facilitation of automatic PF musclesqueeze pressure and lift. Therefore, the purpose ofthis study was to quantify automatic PF activationmeasured as PF squeeze pressure and PF displace-ment, in response to variations in forced expirationeffort in healthy, nulliparous women.

METHODS AND MEASURES

ParticipantsUsing a quasiexperimental repeated-measures design,a convenience sample of 26 young (age 18-35 years),nulliparous, premenopausal women was recruited.

Exclusion criteria included atypical PF muscle activity(caudal descent during a PF maximum volitional con-traction [MVC]), pregnancy, history of lower backor pelvic pain and/or surgical procedures, urinary

incontinence, history of PF dysfunction (bowel incon-tinence, pelvic pain, prolapse), diabetes, endometrio-sis, and neuromuscular or connective tissue disease.

Urinary continence status was assessed usingthe International Consultation on IncontinenceQuestionnaire (ICIQ). This questionnaire was chosenfor its brevity and reliability. 38 Participants scoringmore than zero on questions 1 and 2 on the ICIQwere excluded.

The study was approved by the local univer-sity institutional review board. Informed consent wasobtained for each subject. Medical history and demo-graphic information included age, weight, height, andquestions specic to exclusionary medical conditions.

InstrumentationA breathing device was used to create forced expira-tion using a Portex EzPAP positive airway pressuresystem, with a breathing lter attached to ensure nocontamination between subjects (Smiths MedicalASD, Inc, Keene, New Hampshire). The device wasmodied by interchangeable tubes of differing lengththat provided 3 variations in resistancemeasuredin a laboratory with spirometryat a constant owrate. The ow rate was set at a level that would allow5-second expiration for clinical testing.

Expiration pressure was measured in centimetersof water (cm H 2 O) by a manometer attached to thePortex EzPAP device and was used as an indication

of effort (Instrumentation Industries, Inc, BethelPark, Pennsylvania). The manometer measured pres-sure up to a maximum of 120 cm H 2 O in incrementsof 4 cm. There was a resettable pointer on the dialthat was used to set the target pressure for eachcondition.

To standardize the maximum forced expirationeffort for individual participants, each was instructedto breathe out as forcefully as possible, get to yourmost forceful breathing out as quickly as possible,and continue to breathe out at this force for 5 sec-onds. Participants practiced until they were ableto perform a sustained maximum forced expirationeffort for 5 seconds 3 times in a row. The mean ofthe 3 trials was used for each participants maximumforced expiration effort. Minimum and moderateefforts were then calculated as 33% and 66% of eachsubjects maximum effort, respectively. To practicemoderate and minimum forced expiration efforts, theinvestigator set the pointer on the manometer to thedesired effort. Both the participant and the investiga-tor visualized the manometer to ensure expiration atthe appropriate effort. Participants were instructed to

stay within 1 tick mark above and below the desiredeffort, which was 8 cm H 2 O of variability. The inves-tigator also monitored and cued participants on the5-second expiration duration.


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investigator 1 was caudal to participants, instruct-ing and assessing proper PF MVC performanceand recording the perineometer and USI measure-ments. Investigator 2 was cranial to the participants,instructing the expirations, monitoring expirationeffort, and monitoring and cueing the 5-second timer.

After consent was collected, bladder volume wasstandardized as detailed. Weight, height, and medicalhistory were then taken. Participants were familiarizedwith instrumentation and then investigator 2 instruct-ed maximum forced expiration effort. Moderateand minimum expiration efforts were calculated asdetailed. Participants practiced the 3 variations offorced expiration until they were able to consistentlyexpire at each desired effort for 5 seconds. Then, theywere asked to undress from the waist down and laydown in the testing position.

Pelvic oor MVC was then instructed as squeezethe PF muscles as if you were trying to close allyour openings, and lift the PF toward the top ofyour head. Visual and palpatory assessments wereperformed to ensure that no accessory muscles wereused and no motions through the lumbopelvic areaor thorax were performed during PF contraction.Investigator 1 ensured that there was no gross caudaldescent of the PF by palpation assessment using thedorsum of the hand. Participants were allowed topractice PF MVC until they were able to adequatelyperform the contraction as indicated by visual and

palpation assessment.

Data Collection: PF Squeeze PressureFor standardization purposes, vaginal squeeze pres-sure was rst taken at rest and during a PF MVC.Pelvic oor MVCs were held for 5 seconds, and thepeak pressure was recorded. Consecutive readingswere taken 3 times at rest and then 3 times during aPF MVC, with a 30-second rest after each PF MVC.

Participants were then instructed to exhale attheir maximum, moderate, and minimum forcedexpiration efforts in a randomized order. Participantsperformed 3 trials each of maximum, moderate,and minimum forced expiration efforts (a total of 9trials), and no instruction was given on whether torelax or squeeze the PF during the forced expiration.Expirations were 5 seconds in duration, and the rest-ing and peak vaginal squeeze pressures were recordedduring each expiration. There was a 30-second restbetween each 5-second expiration.

Data Collection: PF PositionPelvic oor position data were taken after PF squeeze

pressure data collection was completed. For exclusionand reliability purposes, the PF position was taken atrest and during a PF MVC, using the on-off methoddescribed earlier. Pelvic oor MVCs were held for

The squeeze pressure of the PF muscles was mea-sured using a Peritron 9300A perineometer witha silicone vaginal sensor probe (Cardio Design PtyLtd, Lara, Victoria, Australia). This manometer hasdemonstrated good test-retest 17 and intra- 18 andinterrater 20 reliability in clinical studies. The sensorprobe with a protective covering and a small amountof gel was inserted in the vagina by the subject toa standardized depth of 7 cm. According to themanufacturer, the optional ination of the vaginalsensor probe decreases the sensitivity of the sensorsresponse, so the sensor was used uninated.

Pelvic oor position was measured by 2-dimensionalTP B-mode USI using MyLab25 (Biosound Esaote,Indianapolis, Indiana) with a 2.5- to 5-MHz curvilin-ear transducer (CA621). The transducer was appliedtranslabially in the sagittal plane according to themethod of Schaer et al 37 to capture an image of thebladder, bladder neck, urethrovesical junction, andpubic symphysis.

For USI, the intrarater reliability to reproduce a con-sistent image for each participant was analyzed by usingthe on-off method. Three images each were taken ofthe PF at rest and during an MVC for 22 participants.The transducer was displaced and replaced on the PFbetween each image. The same 6 images of each par-ticipant were taken again by the same rater using thesame method, at least 24 hours later. The images wereanalyzed using the coordinate system (described in the

Data Reduction section) at a later time.The intrarater reliability to consistently locate theurethrovesical junction using the coordinate system(described in the Data Reduction section) on theultrasound image was analyzed by 1 rater locatingthe structure 5 times each on 10 randomly selectedimages. The structure was located again on the same10 images, 5 times each, by the same rater at least24 hours later.

Bladder Volume StandardizationBladder volume was standardized by asking par-ticipants to void their bladder and then drink 24ounces of water. Approximately 20 minutes passedbetween drinking 24 ounces of water and the USIdata collection.

Testing PositionAll procedures were performed with the participantin the supine position with hips exed to 60 , kneesexed, and a 2-inch towel roll placed under the par-ticipants lumbar spine to provide support and allowfor mild lordosis during testing. 18 , 22 , 29 , 39

Testing Sequence and Data CollectionThe same 2 female investigators instructed par-ticipants and collected data. During data collection,


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5 seconds. The PF position was recorded consecu-tively 3 times at rest and then 3 times on the thirdsecond of a PF MVC. There was a 30-second restafter each PF MVC.

Participants were then instructed to exhale attheir maximum, moderate, and minimum forcedexpiration efforts in a randomized order. Participantsperformed 3 trials each of maximum, moderate, andminimum forced expiration efforts (a total of 9 trials),and no instruction was given on whether to relax orsqueeze the PF during forced expiration. Expirationswere 5 seconds in duration, and the PF position wasrecorded on the third second of each expiration.There was a 30-second rest between each 5-secondexpiration.

For the reliability study, participants were askedto return at least 24 hours later. Investigator 1 took6 images of the PF position, using the on-off methoddescribed earlier. Pelvic oor MVCs were held for5 seconds. The PF position was recorded consecutive-ly at rest and then on the third second of a PF MVC,with a 30-second rest after each PF MVC.

Data ReductionFor TP USI, the pubic symphysis was localized anda coordinate system was created with the x -axis fol-lowing the central axis of the pubic symphysis and they -axis at the caudal-inferior tip of the pubic symphysisand perpendicular to the x -axis 28 , 37 (Figure 1 ). The

bladder neck was located at the proximal ventralurethrovesical junction. Resting position was estab-lished as x 1 , y 1 and end position as x 2 , y 2 . Change inthe bladder neck position was calculated as follows:(1) horizontal displacement in a dorsal-ventral

direction ( x 1 x 2 ); (2) vertical displacement in a cra-nial-caudal direction ( y 1 y 2 ); and (3) a total changein bladder neck position calculated as vector length a(a = b 2 + c 2 , b = y 1 y 2 , c = x 1 x 2 ).28 , 37

Using this coordinate system, negative values in thehorizontal plane denoted PF displacement in the ven-tral direction, whereas positive values indicated dor-sal displacement. In the vertical plane, negative val-ues indicated cranial displacement whereas positivevalues indicated caudal displacement. The verticaland horizontal positions of the PF were calculated asthe average of the 3 trials. The distance function onMyLabDesk program and a manual protractor wereused to draw the coordinate system directly onto theultrasound image after data collection. Investigator1 performed all data reduction while blinded to theexpiration effort condition.

Data AnalysisThe following descriptive statistics (means, standarddeviations, and minimum and maximum values)were recorded for each participant: (1) age; (2) bodymass index; (3) maximum expiration effort; (4)vaginal squeeze pressures during PF MVC; (5) vaginalsqueeze pressures during the 3 variations in forcedexpiration effort; (6) direction of PF displacementduring PF MVC and the 3 variations in forced expi-ration effort; and (7) magnitude of PF displacementduring PF MVC and the 3 variations in forced expira-

tion effort.Inferential statistics were conducted using the SPSSstatistical software (version 15.0, SPSS, Inc, Chicago,Illinois). Intraclass correlation coefcient (ICC 3,3)was used to assess intrarater reliability to reproduce

Figure 1. Coordinate system of measurement. Ultrasound image (A). Representation of ultrasound image (B). Each image islabeled with the following: x , horizontal axis following the central axis of the pubic symphysis; y , vertical axis perpendicularto horizontal axis at the caudal-dorsal tip of the pubic symphysis; a, pubic symphysis; b, bladder; c, bladder neck; and d,proximal ventral urethrovesical junction. Horizontal position is distance from d to y. Vertical position is distance from d to x.


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were analyzed ( Figure 2 ). Participants took 6 to 11trials to consistently expire at their maximum effortfor a 5-second duration. Moderate and minimumexpiration efforts were achieved in 1 to 2 practicetrials. Maximum expiration effort was 45.0 11.7(24-67) cm H 2 O. Each subject remained within 8 cmH2 O with respect to her target expiration effort foreach trial per the manometer.

Intrarater reliability to consistently locate the ure-throvesical junction using the coordinate system (ICC3,5) was 0.99 (95% condence interval [CI] = 0.97-1.00) in the horizontal plane and 1.00 (95% CI =1.00-1.00) in the vertical plane. Intraclass correlation(ICC 3,3) of intrarater reliability to reproduce thesame PF TP ultrasound image on each subject was0.93 (95% CI = 0.86-0.97) in the horizontal planeand 0.84 (95% CI = 0.68-0.92) in the vertical plane.

Descriptive statistical results for squeeze pres-sure (perineometry), PF displacement direction (USI),and mean PF displacement magnitude (USI) duringMVC and 3 conditions of forced expiration effortsare summarized in Table 1 . A PF MVC produceda mean squeeze pressure of 46.2 16.8 cm H 2 O,wherein 100% of the participants displaced the PFin a cranial-ventral direction. A PF MVC resulted ina mean horizontal displacement of 0.60 0.33 cmventrally and a mean vertical displacement of 0.20 0.15 cm cranially.

the same ultrasound image on each subject. Intraclasscorrelation coefcient (ICC 3,5) was used to assessintrarater reliability to produce consistent measure-ments using the coordinate system. A 2 test wasused to analyze the frequency distribution of directionof PF displacement during the variations of forcedexpiration effort. Alpha adjustments were madeusing the multiplicative correction for 3 pairwisecomparisons to maintain a family-wise level of.0167. Because the sample size was small and the datadid not meet parametric assumptions, 2 Friedman1-factor repeated-measures analyses of variance forranked data were used to compare (1) differences inPF squeeze pressure and (2) differences in magnitudeof PF displacement during variable expiration efforts.Wilcoxon signed rank tests with a Bonferroni correc-tion ( = .0167) were used post hoc to locate signi-cant differences.

RESULTS

Of the 26 women recruited, 4 were excluded becausethey did not meet the urinary continence criteria perthe ICIQ. After data reduction, 4 more participantswere excluded because they produced an atypicalcaudal displacement of the PF during an MVC. 3 , 9 , 36 , 40The data of 18 women aged 24.9 2.5 (21-30) yearsand body mass index 22.3 2.3 (18.2-26.6) kg/m 2

Figure 2. Study owchart. Abbreviations: PF, pelvic oor; USI, ultrasound imaging.


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variations, there was a signicant difference betweenminimum versus maximum ( P < 0.001) and moderate

versus maximum ( P = 0.006) conditions. There wasno signicant difference in horizontal displacementbetween minimum and moderate efforts ( Table 2 ).Pelvic oor ventral displacement occurred most oftenduring minimum effort (94.4% of participants), fol-lowed by moderate (61.1% of participants) and maxi-mum forced expiration efforts (16.7% of participants)(Table 1 ). In the vertical plane , PF cranial displacementoccurred in 61.1% of participants during minimumforced expiration versus 33.3% and 22.2% for mod-erate and maximum forced expiration efforts, respec-tively (Table 1 ), which were not signicant ( Table 2 ).

When comparing PF displacement in the cranial-ventral versus not cranial-ventral direction, minimumforced expiration effort produced a signicantlygreater frequency of cranial-ventral displacementthan moderate ( P = .002) and maximum forced expi-ration efforts ( P < .001). There was no signicantdifference in the frequency of cranial-ventral displace-ment when comparing moderate versus maximumexpiration effort ( Table 2 ). Minimum forced expira-tion effort produced cranial-ventral PF displacementin 55.6% of the participants compared with moder-

ate (22.2%) and maximum forced expiration efforts(5.6%) ( Table 1 ). Maximum forced expiration effortresulted in a large percentage of participants (66.7%)displacing the PF in a caudal-dorsal direction.

Vaginal Squeeze PressureWhen comparing vaginal squeeze pressure measure-

ments, there was a signicant difference between all 3expiration conditions ( P < .001) ( Table 2 ). Maximumforced expiration effort demonstrated the highestmean squeeze pressure (12.4 7.9 cm H 2 O), whereasmoderate and minimum efforts were 7.57 5.02 and3.67 2.84 cm H 2 O, respectively ( Table 1 ).

PF Displacement: MagnitudeWhen comparing PF displacement magnitude in thehorizontal plane , the 3 expiration efforts producedsignicantly different mean displacements ( P < .001)(Table 2 ). Maximum forced expiration producedthe greatest mean displacement of 0.23 0.34 cm.Minimum and moderate forced expiration effortsproduced mean displacements of 0.15 0.23 and0.09 0.35 cm, respectively ( Table 1 ).

There was also a signicant difference in PF displacement magnitude in the vertical plane between all3 expiration efforts ( Table 2 ). Maximum forced expi-ration again produced the greatest mean displacementof 0.27 0.29 cm. Minimum and moderate expirationefforts produced a mean displacement of 0.03 0.13 and 0.08 0.20 cm, respectively ( Table 1 ).

PF Displacement: DirectionWhen comparing the displacement direction in thehorizontal plane produced by the 3 forced expiration

Table 1. Squeeze Pressure (Perineometry), Direction, and Magnitude of Pelvic Floor (PF) Displacement (USI) During PF MaximumVoluntary Contraction (MVC), Minimum, Moderate, and Maximum Expiration Efforts

MVC,Mean SD (Range)

Minimum,Mean SD (Range)

Moderate,Mean SD (Range)

Maximum,Mean SD (Range)

Perineometry (pressure in cm of H 2 O), Mean SD(Range)

46.21 16.75(15.4-76.4)

3.67 2.84(0.68-10.70)

7.57 5.02(3.37-19.98)

12.35 7.90(3.65-29.82)

USI (PF horizontal displacement, magnitude in cm) ( ) = ventral, Mean SD (Range) (+ ) = dorsal, Mean SD (Range)

0.60 0.33( 0.09 to 1.31)

0.15 0.23( 0.49 to 0.57)

0.09 0.35( 0.32 to 1.01)

0.23 0.34( 0.20 to 1.34)

USI (PF horizontal displacement, direction), % 100% ventral 94.4% ventral 61.1% ventral 16.7% ventral

USI (PF vertical displacement, magnitude in cm) ( ) = cranial, Mean SD (Range) (+ ) = caudal, Mean SD (Range)

0.20 0.15( 0.02 to 0.64)

0.03 0.13( 0.24 to 0.20)

0.08 0.20( 0.31 to 0.48)

0.27 0.29( 0.16 to 0.98)

USI (PF vertical displacement, direction), % 100.0% cranial 61.1% cranial 33.3% cranial 22.2% cranial

USI (overall PF displacement, magnitude in cm),Mean SD (Range)

0.66 0.32(0.19-1.39)

0.29 0.12(0.14-0.57)

0.36 0.24(0.17-1.06)

0.47 0.35(0.14-1.66)

USI (overall PF displacement, direction), % 100.0% CRV

55.6% CRV 22.2% CRV 5.6% CRV

38.9% CV 38.9% CV 11.1% CV

5.6% CRD 27.8% CD 66.7% CD

11.1% CRD 16.7% CRD

Abbreviations: CD, caudal-dorsal; CRD, cranial-dorsal; CRV, cranial-ventral; CV, caudal-ventral; MVC, maximum voluntary contraction.


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However, these investigators did not incorporate astandardized forceful expiration. Neumann and Gill 13measured the PF response using surface EMG dur-ing a standardized forced expiration of 40 mm Hg(54.4 cm H 2 O) and observed a PF muscle response at57% of maximum activation. They did not objectifythe displacement of the PF during forced expiration,so it is impossible to know whether the increasedEMG activity was concurrent with PF descent orascent. Their forced expiration value was higherthan the mean value of maximum forced expirationeffort produced by our participants. These authorsfound a minimal increase in IAP during isolated PFand abdominal contractions (6-9 mm Hg) whereasforced expiration produced a 36-mm Hg increasein IAP. In concert with their ndings, there waslikely an increase in IAP in our participants during themaximum and moderate forced expiration efforts,which appeared true on the basis of PF displacementrecorded in our study. Maximum forced expirationeffort predominantly led to a caudal-dorsal displace-ment (66.7%), whereas minimum forced expirationeffort predominantly resulted in a cranial-ventralPF displacement. At the minimum forced expirationeffort, participants were most likely to demonstratean automatic PF muscle activation that may haveresisted the effort of forced expiration, leading to PFdisplacement in the ventral (94.4%), cranial (61.1%),and cranial-ventral (55.6%) directions.

Vaginal squeeze pressure is 1 of 2 important PFmechanisms that create continence. 3 , 8 Most inves-tigators have demonstrated a signicant differencebetween participants with stress urinary incontinence(SUI) and controls in resting vaginal closing pres-sure, 33 , 41 maximum closing pressure, 33 , 42 and PFmuscle endurance. 41 Our ndings showed signicantincreases in vaginal squeeze pressure as effort offorced expiration increased. However, intravaginalpressure measurements can be affected by increases inIAP.43 , 44 Because many of our participants depressedthe PF in a caudal-dorsal direction, especially duringmaximum (66.7%) and moderate (27.8%) forcedexpiration efforts, there is an assumption of signi-cantly increased IAP. We hypothesized that minimumand moderate forced expiration efforts would resultin facilitation of automatic PF muscle squeeze pres-sure and lift. Because so many participants depressedthe PF during the moderate and maximum efforts,the vaginal squeeze pressure data had little descrip-tive value in these expiration conditions. For thisreason, also, vaginal squeeze pressure in all expirationconditions was expressed as raw data, rather than a

standardized percentage of each participants MVC.Knowledge of basic and applied physiology of PFmuscle activation is valuable in PF training programs,which have strong support in the literature as an

COMMENT

In this preliminary investigation, PF squeeze pres-sure and displacement in response to a standardizedvariation in forced expiration effort were measured.Because we were interested in gaining normative dataon these measures, we used an asymptomatic popu-lation that had no indication of atypical PF muscleactivation during an MVC.

Overall, a cranial-ventral PF displacement wasobserved most often during minimum forced expi-ration effort. It supports the use of minimumforced expiration effort during PF training pro-grams aimed at enhancing PF displacement in anoptimal and protective direction. The use of suchstrategy should rst be evaluated using PF palpationor USI, as 45% of the participants did not display

a cranial-ventral PF displacement during minimumforced expiration effort.Talasz et al 12 reported a PF cranial displacement

(0.51 0.47 cm) in response to forceful expiration.

Table 2. Comparisons of Squeeze Pressure, Direction of PelvicFloor (PF) Displacement, and Magnitude of PF Displacement byExpiratory Efforts

2 df Z -value P -value

Squeeze pressure a Min vs mod b

Min vs max b Mod vs max b

30.333

2

3.636

3.724 3.463

< .001 *< .001 *

< .001 *.001 *

Direction of PF displacement c Min vs mod (Hor)

Min vs max (Hor) Mod vs max (Hor) Min vs mod (Vert) Min vs max (Vert) Mod vs max (Vert)

4.018 d

22.0507.4812.7865.6000.554

111111

.045

< .001 *.006 *.095.018.457

Direction of PF displacement c Min vs mod (CV vs not CV)

Min vs max (CV vs not CV) Mod vs max (CV vs not CV)

9.402

17.5770.929 d

111

.002 *

< .001 *.335

Magnitude of PF displacement(Hor) a Min vs mod (Hor) b Min vs max (Hor) b Mod vs max (Hor) b

21.778

2

3.332 3.680 2.722

< .001 *

.001 *< .001*

.006*

Magnitude of PF displacement(Vert) a Min vs mod (Vert) b Min vs max (Vert) b Mod vs max (Vert) b

23.408

2

2.635 3.724 3.053

< .001 *

.008 *< .001 *

.002 *

Abbreviations: CV, cranial-ventral; Hor, horizontal; max, maximum;min, minimum; mod, moderate; Vert, vertical.a Friedman 1-way analysis of variance by ranks.b Wilcoxon signed rank test post hoc with Bonferroni adjustment.c 2 test.d With Yates correction.*Statistically signicant.


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activation, so we did not believe that their automaticPF activation would provide normative data.

Because this was an investigation of asymptomaticwomen, it lacks generalizability to other populationsand provides limited information on rehabilitationapplications to symptomatic populations. Furtherinvestigations with larger sample sizes and usingsymptomatic individuals are needed.

Intra-abdominal pressure was not monitored ormeasured because it was beyond the scope of thisstudy. On the basis of the ndings of this preliminaryinvestigation, further studies are warranted to objec-tify therapeutic levels of forced expiration with IAPquantication in symptomatic populations.

CONCLUSION

Forced expiration resulted in PF activation. Minimalforced expiration effort resulted in the most consis-tent cranial-ventral displacement with vaginal closingpressure of the PF. This provides important clinicalinformation on the use of forced expiration in PFtraining programs.

ACKNOWLEDGMENTS

The authors thank Texas Tech University HealthSciences Center for providing equipment and labora-tory space for the completion of data collection for

this study.

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10. Constantinou CE , Govan DE . Spatial distribution and timing of transmit-ted and reflexly g enerated urethral pre ssures in healthy wom en . J Urol .1982 ;127 (5):964 969 .

11. DeLancey JO . Structural support of the urethra as it relates to stressurinary incontinence: the hammock hypothesis . Am J Obstet Gynecol .1994 ;170 (6):1713 1720 ; discussion 17201723.

12. Talasz H , Kremser C , Kofler M , Kalchschmid E , Lechleitner M , Rudisch A .Phase-locked parallel movement of diaphragm and pelvic oor during breath-ing and coughing: a dynamic MRI investigation in healthy females . Int Urogy- necol J . 2011 ;22 (1):61 68 .

appropriate conservative approach for women withSUI. Investigations have demonstrated improvementsin SUI symptoms 45-51 and quality of life 45 , 46 , 52 in PFtraining program participants. The mechanism ofefcacy of such programs has not been elucidated.The relative contributions of PF muscle strengthen-ing,34 , 47 , 50 , 51 bladder neck mobility control, 53 , 54 andimprovements in PF contraction motor control andtiming 15 , 16 to the positive outcomes of PF trainingprograms remain unclear. Conversely, the literatureconsistently reports that conservative SUI manage-ment should emphasize patient education that focuseson methods for increasing PF muscle strength, timing,and endurance during functional forced expirationsuch as coughing, sneezing, and laughing, 4 , 13 , 55 whenurinary leakage often occurs. Despite the importanceof appropriate PF muscle activity before and duringtimes of forced expiration, few authors have dis-cussed respiration concepts and methods in a clinicalPF rehabilitation program. Sapsford 55 and Hunget al 46 were the rst to introduce the respiratoryfunction of the PF and diaphragm to PF rehabili-tation programs. These authors theoretical basisfor retraining diaphragmatic breathing was to leadpatients to a functional forced expiratory patternthat incorporates the diaphragm and abdominal andPF muscles, ultimately improving continence mecha-nisms during forced expiration. On the basis of thepresent study, a simulated forced expiratory pattern

at minimal effort facilitates an automatic squeezingcontraction with a cranial-ventral displacement of thePF. Clinicians can use this facilitation to achieve theappropriate PF squeeze with cranial displacement. Inaddition, individuals will improve PF strength andtiming strategies during times of functional forcedexpiration, when they most need effective control forcontinence. Pelvic oor rehabilitation programs usingminimal forced expiration effort could be used inSUI prevention programs for asymptomatic, prenatalpopulations. Further research is needed before spe-cic suggestions can be made regarding PF trainingprograms using forced expiration effort on symptom-atic populations.

Methodological ConsiderationsWe used a small, convenience sample of womenbecause of the invasive component of this study. Inaddition, we excluded 18% of our participants (4/22)because they were unable to demonstrate typicalPF activation during an MVC. This exclusion wasjustied because we were interested in automatic PFactivation in a normal population that demonstrated

typical PF activity. Participants who demonstratedPF caudal displacement during a volitional contrac-tion were already outside the limits of typical PF


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Research Report

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effect of variations in forced expiration effort.4

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