Elizabeth
Lewis, PT, OCS, WCS
Oct. 14,
2015
Pelvic
Physical Therapy Distance Journal Club
Description: This systematic review had a stated
purpose of developing a better understanding of PFM activation and strength
components in order to develop more specific PFM training regimens for female
SUI patients. The aim of this systematic
review was to summarize/evaluate existing studies investigating PFM
activation/strength components which influence female continence and SUI.
Introduction:
PFM-
training for SUI is effective and so is recommended as a first line of
therapy. However, the optimal training
regimen for achieving continence is still unknown. There is a question among
caregivers of optimal PFM training protocols.
There is high variability in PFM training protocols. A Cochrane review showed insufficient
evidence (due to heterogeneity) to make any strong recommendations about the
best approach to PFM training (in terms of supervision and content of
programs). Although specific training
methods and principles have been well described in the rehab/training
literature, PFM training needs to include them to improve maximal strength,
power, hypertrophy, strength-endurance and related muscle action forms. Also, PFM
training should also include periodization, which specifies optimum frequency,
intensity and type of contraction during training sessions. An understanding of
PFM activation in terms of the neuromuscular dimension is also necessary.
Methods: They used PRISMA (preferred
reporting items for systematic reviews and meta-analyses) guidelines and
published their a priori protocol in PROSPERO (register of SR reviews in health
and social work). This was a systematic review vs. a
meta-analysis because of the high heterogeneity of the data. The search strategy included strength and
activation related terms (such as muscle strength, force development rate and
power), clinical condition of SUI, terms assoc. with PFM and measurement
methods such as EMG, pressure, force, etc.
Studies reviewed were in English, French, Dutch and German (due to
reviewers).
(A systematic review comprehensively searches
all related studies on a topic with a goal of reducing bias by identifying,
appraising and synthesizing all relevant studies of a particular topic. A systematic review can include a
meta-analysis: which uses statistical techniques to synthesize data from
several studies into a single quantitative estimate or summary of effect size. A narrative review vs. a systematic review is
based on availability or author selection of studies and so can have the risk
of selection bias.)
Information taken from internet, not from this study.
Search Strategy: They did a systematic search of
the literature from January, 1980- November of 2013 in Pub Med, EMBASE and Cochrane
databases for cross-sectional studies comparing female SUI patients with
healthy controls and interventional studies of female SUI patients, looking at
the association between PFM strength and activation and urine loss. Their
search terms included terms for strength/activation, terms associated with the
muscle nomenclature, clinical condition (SUI) and measurements methods such as
pressure or EMG.
Inclusion and exclusion criteria were listed in Table 1, looking at Population: Female adults, with SUI
stage 1-3, 1 yr PP, parous, nulliparous, pre- and post- menopausal, Interventions/exposures: EMG and or
strength-measurements of PFM components with various electrodes and probes, Comparator: a) Healthy controls b) SUI
patients pre and post PFM therapy .
Main Outcomes:
a) Cross sectional studies reviewed: Association /no association between
CON/SUI and specific PFM components of
women with SUI vs healthy controls and
b) Pre and Post studies reviewed
Association/no association between CON/SUI and specific PFM components of women with SUI before/after PFM therapy.
They
looked at PFM components, definitions, measurement methods, study outcomes and
quality measures independently extracted based on the Cochrane risk of bias
tool
Results: Selection of studies went from 2,
630 abstracts to fourteen (see article).
Nine studies were cross sectional, comparing SUI with healthy controls
and five were clinical trials or intervention studies, (non-controlled pre-post
design on females with SUI). Two
cross-sectional studies were looking at the same sample with different
questions and two were investigating a vaginal probe, regarding the physics and
clinical data.
Table 3
shows the cross sectional studies and their characteristics. Measurement methods varied: Six studies
measured strength with varied terminology including force or pressure and
measured in Newtons or mmH20. Three
studies used EMG amplitude with varying probes.
Measured PFM components and their definitions were highly heterogeneous.
Risk of Bias is in Table 2 and include (“+”
here means succeeded to attain a low risk of bias) : (Summarizing for all nine
studies), random sequence generation (selection bias) + in 2 studies(low risk
of bias in 2 studies) , Allocation concealed (selection bias), + in 9 studies,
Blinding of participants (not possible) and personnel (performance bias) + in 2
studies, Binding of Outcome assessment (detection bias), + in one study, Incomplete outcome data ( attrition bias) +
in 5 studies, Selective reporting (reporting bias) + in all studies and, Other
sources of bias (+ in one study).
Table 4
summarizes the major characteristics of the five pre and post studies. All studies used PFMT and two were secondary
data analyses and one also used IFES.
The PFMT protocols and the measurement methods varied widely. All studies measured strength, (terminology
was strength, force or pressure). Probes
varied but were well established devices.
Changes in SUI were assessed with pad tests (varied) among other methods
and all studies showed an improvement of the SUI component
measured and decreased urine loss after intervention.
Again, pooling
of data for meta-analysis wasn’t possible due to high heterogeneity.
Discussion: Higher maximal, mean, endured and
increase of PFM strength and earlier onset PFM activation were positively
associated with female continence.
However, studies are heterogeneous in terms of methodology and
terminology as well as definitions of the PFM activation and strength
components and their characteristics.
Unclear terminology, test instructions and applications were applied,
such as EMG measures not normalizing raw EMG data to compare independent groups
(continent, SUI). This, in addition to
lack of information on the exact interventions given and the lack standardization
of each intervention, limits the comparison of outcomes among the studies.
Strengths: First comprehensive systematic
review on the topic of PFM activation and strength components influencing
female continence and SUI. They had a
strong interdisciplinary team to do the literature review.
Weaknesses: Small number of trials and subjects,
heterogeneity of terminology, test procedures and outcomes, so they couldn’t do
a meta-analysis. Subject ages varied
widely, from 30—60 but didn’t include women over 70 (they said: a large group
with SUI missed).
Conclusion: Noting the limitation of high
methodological variability across these studies, this study suggests that PFM
strength and activation components are associated with Female continence and
SUI and generally supports the import of PFM training because improvements in
PFM function may be related to improvement in SUI symptoms. But it’s difficult to get a clear cut picture
of SUI mechanisms.
They
recommend more detailed knowledge about physiological and pathophysiological
function of the PFM in terms of activation and strength (such as muscle
metabolism, muscle action forms, sensorimotor and muscle fiber recruitment
behavior, inhibition, voluntary/non-voluntary contractions, maximal strength,
rate of force development and all combined.
PFM
function has to be clarified for functional movements with SUI provoking
impacts such as running, coughing, etc. and not only in non- functional test conditions
(MVC in supine).
Specific
PFM training protocols could be developed on the basis of findings from
consistent terminology, standardized instructions of patient’s test behaviors
to provoke the respective PFM component and with well-matched diagnostic
equipment.
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