The effect of abdominal and pelvic floor muscle activation on urine flow in women. Sapsford RR, Hodges PW. Int Urogynecol J; Jan 26, 2012 (Epub ahead of print).

 Ann Dunbar May 9, 2012

Primary Aim: To determine whether urine flow can be interrupted or stopped when effort is made to stop the flow with a strong contraction of the lower abdominal muscles in healthy women and if present, to compare the time required to interrupt flow comparing a maximal voluntary pelvic floor muscle (PFM) contraction and a strong abdominal drawing-in.

Subjects:

Female physiotherapists who were familiar with PFMs, reported ability to contract them voluntarily and were without any of confounding criteria listed in study (n=10)

Study Design: Quasi-experimental


Methods:

Urine flow measurement 

• Flow time (time from start of urination to cessation of flow, seconds)
• Time to max flow (time from start of urination to peak flow, seconds)
• Maximum flow rate (amplitude of max flow, ml/sec)
• Voided volume (total volume of urine voided during urination, ml)
• Trace of flow curve produced
• Time to interrupt flow calculated as ‘flow time’ minus ‘time to maximum flow’ (time to stop, seconds)
• Latency between flow of urine and recording at base of device calculated (3 sec) (Note:  start of urination determined by recording mechanism at base of funnel-shaped collection device in flowmeter signaled by a light)

Familiarization procedures

Prior to testing, subjects attended session for instruction in lower abdominal contraction at end of expiration with standardized use of ultrasound imaging. Correct activation of pfm confirmed by external palpation of perineal body, upward movement with contraction and downward with relaxation.

Procedures

Testing done twice, 1 to 2 wks apart. Subjects were non-menstruating and had comfortably full bladder. They were given instruction in non-randomized pattern as to which muscle pattern to use (PFM contraction or lower abdominal ‘drawing in’; see paper for details). They were given command to either stop or interrupt their urine stream 4 sec. after sensor light indicated stream initiation. Alternate contraction pattern investigated at second session.

Data Analysis

Studied flow time, time to maximum flow, time to stop the flow, maximum flow rate, flow at time of stop, and voided urine volume. These were compared between PFM and abdominal muscle contractions with t –test. Relationships between voided volume / peak flow and between voided volume / time to stop flow were assessed with Pearson’s correlation coefficient to determine whether a relationship existed between the results of the aforementioned measures and voiding volume.

Results

Urine flow stopped with both PFM and abdominal drawing in maneuver

• PFM mean 4 sec (2-8)   and Abdom mean 4.3 (2-7)  (p=0.78)

At time of command, mean maximal flow rate greater for PFM trials than Abdom

• PFM mean 23.5 ml/s and Abdom mean 22.4 ml/s; (p=0.81)

No significant relationship between voided volume and maximal flow

• Voided volume (R²=0.12) and maximal flow (R²=0.01)

Discussion

Authors suggest the slowing and stopping of urine flow with the use of Abdominal drawing-in strategy occurs because of the co-contraction with the peri-urethral muscle complex with or without a contribution from levator ani.

 Methodological Considerations:

• Participants not “naïve” to the study aim
• Participants instructed to contract PFM or do abdominal maneuver, no co-contraction was mentioned
• Some participants hesitated in starting stream which challenged results; 2 dropped out
• Not possible to monitor muscle activity during trials

Cessation of urine flow:

• Time for PFM contraction to stop urine flow was longer than data from another study
• Urine flow at time of command to stop was similar to data from previous study and PFM flow greater than abdominal maneuver
• Results cannot be extrapolated; need to do study with larger population, not just PTs

Co-coordinated pelvic floor and abdominal muscle activity

Authors ask: “How can voluntary contraction of the PFM and the lower abdominal muscles (TrA and OI) produce similar effects on urine flow?”

Previous research findings:                        

• Voluntary abdominal m. activity generates PFM activity
• Amplitude of PFM activity recorded during PFM contraction is same as PFM amplitude recorded during a strong “drawing-in” maneuver.
• Bladder base elevates with mild co-contraction of TrA andiInternal oblique (per US imaging)
• Peri-anal and peri-urethral EMG activity reduced only when abdominal muscles were relaxed in stable sitting position, ie with feet on the floor.
• Increased mid urethral pressure with TrA contraction
• Sacral stimulation leads to activation of both PFM and abdominals in the motor cortex

Clinical Application

• Concerns about the study design (not possible to monitor muscle contractions during testing) and any solutions?
• Would these findings cause you to change anything in your treatment program? Eg, Abdominal exercise? More work with Type II fibers?   How to teach The Knack? Integration into ADLs?

www.pelvocpt.blogspot.com post of Feb 1/2012 reports on several articles related to the urine interruption test.