Key words
pelvic floor training - pelvic floor rehabilitation - bladder neck - perineal ultrasound
- pelvic floor contraction
Introduction
Urethral closing pressure, precontraction of the pelvic floor and bladder neck stability
are factors that ensure urinary continence [1], [2], [3], [4]. It is known that the bladder neck (BN) descends further on coughing in women with
stress urinary incontinence compared to continent women [5]. In contrast, correct pelvic floor contraction (PFC) elevates the bladder and bladder
neck (ventro-cranial movement) [5], [6], [7], [8]. The bladder neck is stabilised and descends significantly less if PFC is performed
before and maintained during coughing [9]. Both bladder neck descent and elevation can be well documented on two-dimensional
perineal ultrasound and can be quantified using validated methods [7], [8], [10].
Pelvic floor contraction before coughing or other exertions that cause an increase
in intraabdominal pressure has been termed “The Knack” or pelvic floor precontraction
[11]. Learning this skill is part of modern pelvic floor rehabilitation and is specifically
taught in international programs [11], [12], [13], [14]. However traditional pelvic gymnastics training in Germany is mostly comprised of
nonspecific exercises. In healthy women these nonspecific exercises may lead to pelvic
floor contraction through coactivation of abdominal or gluteal and pelvic floor muscles
[15], [16], [17], however it is not known whether the desired bladder neck elevation or at least
stabilisation is achieved. In addition, this automatic co-contraction can only be
expected in healthy subjects [17] and not in incontinent women: In healthy, continent women pelvic floor precontraction
occurs before a potentially destabilising activity and/or actions leading to increased
intraabdominal pressure. In contrast, this precontraction may be lost in incontinent
women [18], [19], [20], [21]. There are no data on the efficacy of traditional pelvic floor gymnastics as currently
performed in Germany.
The pelvic floor is increasingly being integrated into yoga and Pilates programs,
which are offered for both treatment and prophylaxis. The fact that 20 – 43% of women
cannot tighten their pelvic floor musculature on command, or worse even bear down
[22], [23], [24], is not sufficiently taken into consideration by fitness or traditional pelvic floor
gymnastic programs on offer.
The aim of this study was to determine the position of the bladder neck using perineal
ultrasound during selected exercises from traditional German pelvic floor gymnastic
exercises and Pilates in healthy women.
Materials and Methods
Subjects, inclusion and exclusion criteria
Fifteen healthy women without pelvic floor symptoms (screening using a validated pelvic
floor questionnaire) [25] and no previous vaginal births or urogynaecological operations were consecutively
recruited via notice boards and informational events. All women gave written, informed
consent. The measurements were part of a multilevel DFG (German Research Foundation)
funded project that was approved by the Charité ethics commission. Women with previous
vaginal births were excluded, since vaginal birth may lead to permanently altered
bladder neck position [6], [26], and the effects of levator avulsion (muscle disruption from the inferior pubic
rami), which occurs commonly, are uncertain [27]. The ability to voluntarily contract the pelvic floor musculature was a further
inclusion criterion and was tested by palpation and perineal ultrasound. All examinations
were performed by the same investigator (BJ) at a bladder volume of 150 to 300 ml
for optimal visualisation of the bladder neck [10] without subjects having an urge to urinate.
Exercises
Study subjects performed the following exercises, all of which are possible with simultaneous
application of the perineal ultrasound probe (abdominal probe) ([Fig. 1]): the shoulder bridge, the abdominal press, tiptoe and the Pilates clam exercise.
The first set of exercises was performed without any instructions regarding the pelvic
floor. For the second set, women were instructed to voluntarily contract their pelvic
floor muscles prior to starting each exercise (pelvic floor precontraction = PF-preC)
and to maintain the contraction throughout each exercise. A physiotherapist with Pilates
experience gave the instructions. Each exercise lastet for 3 – 7 seconds. We purposely
omited repetitions when the quality of the measurement was deemed satisfactory. There
were not more than three repetitions to improve study quality for any of the exercises.
Averages were not calculated.
Fig. 1 Study exercises: shoulder bridge (a), abdominal press (b), standing on tiptoe (c) and Pilates clamshell (d).
Ultrasound measurements
Bladder neck movements during the exercises were recorded on perineal ultrasound (abdominal
probe RAB 4 – 8-D, 5 MHz, Voluson E8, GE) and saved as videos in a computer program
(Tele Myo “Human performance measurements solutions” MR 3.0; Noraxon USA Inc). The
analysis was conducted offline by one investigator (KB) using a validated digital
tracking system [28]. Standardisation was performed according to Dietz with the distal pole of the pubic
symphysis used as the reference point for both the x- and y-axis [29]. A prerequisite for this is that the ultrasound probe with its outgoing cable remain
strictly in line with the body axis since changes in the tilt angle would result in
false measurements [30] ([Fig. 2]). Visible “shifting” of the symphysis, e.g. through increased intraabdominal pressure
during an exercise, was corrected in analogy to the validation according to Reddy
et al. [28]. The minimal detectible change in bladder neck movement on perineal ultrasound was
established at 3 mm [7].
Fig. 2 Schematic depiction of the bladder neck, the coordination system and correct application
of the ultrasound probe. Typical position during bladder neck descent (red) and bladder
neck elevation (green).
Analysis
All acquired data were analysed using the statistics program SPSS 22. Paired t-tests
were used to compare bladder neck movements between exercises for normally distributed
variables.
Results
Study subjects
Participants were aged between 21 and 45 years (median 32 years) with a median BMI
of 23 (18 – 31 kg/m2). Eight women were nulliparous and seven had given birth to one or two children via
caesarean section. All women were able to perform bladder neck elevating pelvic floor
contractions that were palpable and demonstrable on ultrasound.
Exercises without pelvic floor precontraction
Results are summarised in [Table 1]. Bladder neck (BN) movement during the exercises was highly variable and not identical
among all women for any of the exercises. When performed without voluntary pelvic
floor precontraction all exercises were associated with BN descent between 2.3 and
4.4 mm on average. In contrast to the shoulder bridge and abdominal press (BN descent
− 3.2 and − 4.4 mm respectively), the Pilates clam and tiptoe exercise stabilised
the bladder neck best (− 2.3 and − 2.6 mm respectively), however, differences between
individual exercises were not statistically significant. [Fig. 3 a] to [c] shows the typical progression of bladder neck descent on perineal ultrasound in
a woman with BN descent during the exercise.
Table1 Average bladder neck descent in mm (standard deviation) for series of exercises without
and then with pelvic floor precontraction (PF-preC). Negative values represent bladder
neck descent, positive values bladder neck elevation. Paired t-test for comparison.
|
Without PF-preC
|
With PF-preC
|
p
|
|
Shoulder bridge
|
− 3.2 (2.8)
|
− 2.1 (4.8)
|
0.574
|
|
Abdominal press
|
− 4.4 (1.9)
|
− 2.2 (4.2)
|
0.007
|
|
Tiptoe
|
− 2.3 (3.9)
|
2.7 (3.2)
|
0.086
|
|
Clam
|
− 2.6 (1.9)
|
− 0.5 (4.8)
|
0.580
|
Fig. 3 Typical perineal ultrasound images before, during and after the shoulder bridge exercise
from a woman with significant BN descent: a at rest, b obvious bladder neck descent during the exercise, c almost complete return to normal position after exertion.
Exercises with pelvic floor precontraction
Pelvic floor contraction prior to the exercises temporarily elevated the bladder neck
in all women, however there was subsequent BN descent of 0.5 to 2.1 mm on average
during execution of the shoulder bridge, the abdominal press and, to the smallest
amount, the clam exercise. The original BN elevation of 2.7 mm was maintained while
standing on tiptoe, though there were no statistically significant differences between
the exercises. [Fig. 4 a] to [c] shows an example of stable BN position with the pelvic floor contraction maintained
for the entire duration of an exercise.
Fig. 4 Typical perineal ultrasound images of a woman able to stabilise the BN for the duration
of the shoulder bridge exercise: a at rest, b pelvic floor precontraction prior to exercise causes BN elevation, c bladder neck stabilised with elevation held until exercise end.
Comparison of bladder neck descent for exercises with and without pelvic floor precontraction
There was less BN descent for exercises with PF precontraction than without, however
the difference was only statistically significant for the abdominal press (p = 0.007).
Discussion
This study in a small number of healthy, continent women shows that traditional gymnastic
exercises for the pelvic floor do not necessarily stabilise or elevate the bladder
neck. This also applies when women contracted their pelvic floor muscles – with bladder
neck elevation demonstrated on ultrasound – prior to performing the exercises. Although
a specific pelvic floor contraction initially lead to BN elevation in all the women,
this bladder neck position was rarely maintained for the entire duration of the exercise.
The Pilates clam exercise and standing on tiptoe achieved the best bladder neck stabilisation.
BN descent was most marked with the abdominal press, however a voluntary pelvic floor
precontraction significantly reduced this descent.
Our study subjects were all able to evidently contract their pelvic floor muscles
on command. However, this ability can neither be assumed for all healthy women, nor
for incontinent women. A significant proportion of incontinent women is not able to
contract their pelvic floor muscles [22], [23], [24] and physiological pelvic floor precontraction is not always present [19]. Our results imply that the studied exercises can not provide the desired effects
for many incontinent women, since not all physiotherapists (or gynaecologists) in
Germany test the status of the pelvic floor musculature by palpation e.g. before physiotherapy.
It can be presumed that in many women with pelvic floor disorders the bladder and
urethra descend even further during these traditional exercises, especially when women
are unable to voluntarily tighten their pelvic floor muscles. Although gymnastic exercises
and Pilates or yoga certainly can achieve a coactivation of the pelvic floor, this
does not automatically translate into BN elevation or stabilisation. Also, the principles
of the actually intended muscle training are neglected: specificity, overload and
reversibility [31]. The first of these involves specific contraction of the pelvic floor, which internationally
is most often assessed on vaginal palpation by the therapist. The second, overload,
is achieved through purspecific contractions at a much higher intensity than the involuntary
contractions occurring in day-to-day life e.g. through co-contraction. The third characteristic
of a muscle training program, reversibility, shows up the limitations of an otherwise
internationally successful pelvic floor training program based on increasing the muscle
strength [32]. Physiotherapy studies that increase pelvic floor muscle strength attribute decreasing
continence rates after a number of years to reduced adherence and discontinuation
of training. It is currently being investigated whether a pelvic floor rehabilitation
program conceptually based specifically on coordination, BN elevation and pelvic floor
integration into everyday life [13] could provide long-term success. From work on the multifidi muscles, which, like
the pelvic floor, are predominantly composed of type 1 (slow-twitch) fibres, rehabilitation
for back pain is known to be effective in the long-term without further training [33].
Stabilising the bladder neck, which is partly achieved by sufficient pelvic floor
contraction, is essential for ensuring continence [1], [34], [35]. Perineal ultrasound allows good visualisation and quantification of bladder neck
elevation and descent. It is thus suitable for use as a biofeedback instrument and
is increasingly being used by physiotherapists for pelvic floor rehabilitation [8], [13], [36], [37], [38]. Vaginal and/or rectal palpation do however appear to be essential for assessing
the pelvic floor anatomically and functionally, enabling the development of individualised
rehabilitation programs. Pelvic floor palpation is currently not part of physiotherapy
training in Germany and appropriate skills have to be acquired at palpation courses.
It can be assumed that bladder neck descent occurs during many other exercises and
sports, especially among women with pelvic floor disorders. A comparative study on
this subject is currently in progress. Further studies are needed to define physiological
ranges, to investigate whether sport can worsen pelvic organ prolapse and whether
e.g. pelvic floor precontraction before exertion or other bladder neck supporting
measures such as pessaries can prevent pelvic organ prolapse.
Limitations of this study are the small number of study participants and the difficulty
performing perineal ultrasound for all the study exercises. The minimal detectable
change in bladder neck movement on perineal ultrasound is 3 mm [7], which was achieved in our study for most of the exercises. Strengths of the study
are the use of validated measurement techniques including questionnaires and ultrasound
assessment and interpretation. In addition, the acquisition of data from healthy women
contributes to the establishment of normal values and the planning of future studies.
Conclusion
Traditional gymnastic exercises for the pelvic floor frequently lead to bladder neck
descent in continent women. The bladder neck descends less when the pelvic floor is
contracted prior to, and held for the duration of an exercise. Since the ability to
voluntarily contract the pelvic floor cannot be generally assumed, the traditional
gymnastic exercises for the pelvic floor in Germany without prior confirmation of
correct pelvic floor contraction, should be abandoned.
