Pelvic Physiotherapy Think Tank
July 6, 2011
Ann Dunbar PT, DPT, MS
Introduction
1. Contraction of pelvic floor muscles (PFMs) elevates bladder neck and compresses urethra and provides firm base against which urethra is closed by increases in intra-abdominal pressure (IAP)
a. Authors conclude this is important for continence but probably not determined by PFM activity alone (eg: increased IAP may prevent elevation)
2. Study aims: (1)” to compare displacement of bladder neck, IAP, PFM and abdominal EMG between range of different abdominal and PFM contractions that aim to induce different pressures and m. activation patterns including sub-maximal efforts and (2) compare activity of PFM and abdominal m. and IAP between maximum contractions of each m.”
Methods
1. Sample of convenience; 9 women without PFM disorders; mean characteristics: age=42; height= 5’ 5”; weight = 146 pounds; in cohort, 4 are nulliparous, 5 had 1 to 2 vaginal deliveries
2. Bladder neck displacement assessed with perineal US
3. EMG
a. Vaginal PFM EMG recorded using Periform (manufacturer’s information listed)
shown in past to record PFM activity without crosstalk from other mm.
b. Vaginal EMG and perineal US recorded in separate trials because placement of
intravaginal EMG probe interfered with perineal US
c. Abdominal EMG recorded on R side with combination of fine-wire and surface
electrodes (equipment details listed)
d. Electrodes inserted with US guidance into lower transverse abdominis (TA) and
internal obliques (OI), middle TA and external oblique (OE), and rectus
abdominis (RA)
e. Surface electrodes placed over OI and OE
4. IAP
a. Recorded with custom-made air filled pressure catheter inserted into rectum and positioned cranial into external anal sphincter
5. Experimental tasks
a. Positioning: subjects supine with knees and hips flexed over pillow
b. Completed 6 tasks
i. Gentle PFM contraction—instructed to contract with effort of 2 on a 15
point modified Borg scale (“very light effort”). Had 1 investigator providing feedback and checking EMG. Subjects instructed to relax completely and then “gently lift” and tighter PFM with very light effort and maintain before breath in
ii. Moderate PFM contraction---similar but with effort of 8 on Borg Scale,
“moderate” or “somewhat hard effort”
iii. Isolated contraction of TA---contract with effort of grade 2 “draw-in”
without activating other abdominals per EMG. Subjects given feedback from
palpation of m. and US
iv. Brace contraction---instructed to brace by tightening abdominals while
widening waist with effort equal to 2
v. Valsalva---subjects performed forced expiration against closed glottis with
effort of 2
vi. Head lift---did gentle sit-up with effort of 2
6. Standardized maximum voluntary contractions done at start of trial in supine
including PFM, TA, OI, OE, RA, and IAP
Statistical Analysis:
1. See article (ANOVAs, t-test; Alpha level set at P<0.05)
Results
1. Bladder neck elevation (BNE) between 1.0 (0.3) and 3.3 (1.5) mm during contraction of PFM (Gentle and Mod) and TA but not Brace, Valsalva, and Head lift (P>0.56)
a. BNE during Mod PFM greater than all other tasks (P>0.002)
b. BNE during Gentle PFM greater than all Abd maneuvers (P>0.04)
c. BNE greater with TA than head lift or brace (P>0.03)
d. No difference in BNE between Head lift, Brace, Valsalva (P>0.33)
2. IAP increased in all tasks (see Fig 3) (P>0.05)
3. PFM EMG increased with all PFM and Abd tasks (all: P<0.01)
a. For Gentle PFM task, PFM EMG activity less than in Mod PFM task (P<0.01) but greater than during Brace, Head lift and Valsalva (P=0.01)
b. PFM activity similar during Gentle PFM and TA contraction (P=0.179)
c. PFM EMG activity greater during all Mod PFM tasks (P=0.014) than all other tasks (all:P>0.01)
4. Low TA EMG activity increased with all maneuvers except Gentle PFM (all:P<0.007)
5. Mid TA EMG increase with brace (P<0.02) and Valsalva (P<0.09) tasks; no change in Mid TA EMG with the TA, Gentle and Mod PFM contractions
6. OI EMG increased with Mod PFM, Brace, Valsalva (P<0.02) but not gentle tasks (Head lift, TA, PFM; all: P>0.19)
a. No increase in OE EMG (P>0.22) or in the RA EMG (P>0.10) in any task
7. Relationship between BNE, IAP, and Abd m. activity shown in Fig. 3
a. Summarized data suggest bladder neck is elevated during PFM contractions however, IAP increases as well; authors suggest PFM activity is sufficient to overcome pressure with the result being BNE
b. During Abd tasks (except TA task) no bladder neck elevation occurs; authors suggest that the PFM activity is not sufficient to overcome downward pressure from IAP on the PFM
c. With Max PFM, activity of all Abd mm. increased between 8.2% and 32.8% of the maximum voluntary contraction
Discussion
1. BNE during PFM contraction is influenced by relationship between PFM activity and IAP
2. BNE occurred consistently only with PFM and Gentle TA
3. Gentle Brace, Valsalva, and Head lift increased IAP and prevented significant BNE
4. With OI, OE, RA m. contractions, PFM activity was not sufficient to overcome IAP; no BNE occurred
5. Current study also showed co-contraction of PFM and TA already present w/ sub maximal effort
Methodological Considerations
1. Superficial EMG recordings have potential for crosstalk: strong PFM contraction with Max OE and OE with thigh and UE resistance was unexpected (demand for PFMs with these tasks was small) suggesting possible crosstalk from hip rotators
2. Authors used Borg scale to standardize effort of contractions, a strength of the study
3. Authors state they purposefully chose to study sub maximal effort because there is minimal interference from other mm.
Co-ordination Between PFM and Abd M
1. Results of this study may help explain discrepancies from previous studies
a. Authors list other studies suggesting PFM/TA contraction accompanied by bladder neck descent in some women
b. These studies involved higher PFM efforts which lead to co-contraction of other Abd mm.
2. Current study suggests differences in activation of Mid and Lower TA; authors list other studies identifying morphological and functional differences; Authors suggest current study confirms Lower TA is more active with PFM and Gentle TA contractions
Implications for PFM Rehabilitation
1. Outcomes suggest maximal PFM contraction is associated with activity of all Abs which increases IAP; This needs to be considered in PFM rehab since women with stress UI have been shown to have greater OE activity during maximum PFM and during postural perturbation
a. Suggest multifaceted assessment of PFM with consideration of bladder neck position, IAP, and activity of PFM and Abs
2. Initial activation of PFM achieved by gentle contraction of TA; it may be helpful for women unable to perceive PFM to use this strategy and then proceed to appropriate PFM training for strength and coordination
Conclusion
1. Although co-contraction of lower part of TA and PFM occurred with all tasks, BNE occurred consistently only during PFM and TA contraction
2. When OI is recruited with Valsalva, Head lift, and Brace, PFM contraction was not sufficient to overcome the greater increase in IAP in order to elevate the bladder neck
3. Because a maximum PFM contraction is associated with activity of all the Abs as well as considerable increases in IAP, authors chose to study sub maximal efforts and confirmed that PFM and TA are recruited “concomitantly”
Discussion Questions
1. Are there findings from this study that would lead you to change your practice?
2. What is the optimal strategy for teaching PFM exercise?
3. How do the findings in this study affect your understanding of the optimal PFM exercise prescription?
Journal club participants had many points and discussions about this article. Lots of good interaction. Listen to the recording for full details.
Other articles of interest brought up
Weir LF et al Postoperative activity restrictions any evidence? Obstet & Gynencol 2006;107:305-309.
DeLancey J. Why do women have stress urinary incontinence? Neurourology and Urodynamics. 2010 29(S1):pages S13–S17.
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