Correspondence and requests for reprints should be directed to:
Shari A.
Rone-Adams, DBA, MHSA, PT, GCS
Associate Professor
College of Allied Health and Nursing
Program in Physical Therapy
Nova Southeastern University
3200 S. University Drive
Ft. Lauderdale, FL 33328
(O) 954-262-1284
(Fax) 954-262-1783
srone@nova.edu
Citation:
Rone-Adams, S., Shamus, E., Hileman, M. Physical therapists evaluation
of the trunk flexors in patients with low back pain. The Internet
Journal of Allied Health Sciences and Practice. April 2004. Volume 2
Number 2.
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Abstract
Study Design: This study utilized a
single blind design in the observation of 20 initial low back
evaluations performed by physical therapists. The physical
therapists were blinded to what the researchers were observing.
Objective: The objective of this study was to determine whether or
not physical therapists were quantifying the strength of trunk
flexors when the patient’s chief complaint was low back pain.
Background: The literature has shown that there is a relationship
between back pain and decreased strength in the abdominal muscles.
Therefore, it appears important for physical therapists to
evaluate the abdominal muscles in patients with low back pain.
Methods and Measures: Twenty physical therapists participated in
the study. The researchers observed if trunk flexor strength was
quantified during the initial evaluation of 20 patients with low
back pain. Following the observation, each physical therapist was
given a questionnaire and asked to comment on their evaluation of
the trunk flexors. Results: Of the evaluations that were observed,
15% of the physical therapists evaluated the trunk flexors and 85%
did not. Conclusion: This study demonstrated that therapists did
not consistently quantify abdominal strength when treating
patients with low back pain.
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Key words and
terms: back pain,
abdominal muscle weakness, trunk flexor strength, functional
abdominal strength |
INTRODUCTION
Studies indicate that 70-80% of the population
experience at least one episode of back pain during their lifetime.1,2 Several factors have been associated with the
incidence of low back pain. The literature has identified clinical
factors to include changes in lumbar lordosis and pelvic tilt, leg
length discrepancy, foot pronation, and the length, strength and
endurance of various muscles of the trunk and lower extremity.3
One of the factors that has been highly associated with low back pain
has been abdominal muscle weakness. Studies have investigated
abdominal muscle weakness and its mechanical effect on the back. Some
studies have speculated that weak abdominal muscles result in an
increased anterior pelvic tilt and lumbar lordosis, while other
studies have negated the relationship between pelvic tilt, lumbar
lordosis and abdominal muscle weakness.4-7 But the
fact remains that many studies have shown that patients with low back
pain have weaker abdominal muscle strength than healthy controls.3, 8-15
In 2002, Nourbakhsh and Arab3 performed a study
with 600 men and women that showed that one of the factors associated
with low back pain was decreased strength in the abdominal muscles.
Other factors also associated with low back pain included muscle
length and endurance of the back extensors, and strength of the hip
flexors and hip adductors.3 Lee et al.14
investigated various factors associated with low back pain in an
industrial setting. A cross sectional study was carried out among
1,562 employees of a large utilities corporation. The results
indicated that abdominal muscle weakness was associated with chronic
low back pain. Bayramoglu et al.15 found that in a sample
of 25 female patients who had been experiencing low back pain for at
least 3 months, that decreased trunk muscle strength (extensors and
abdominals) and increased body mass index was directly associated with
chronic low back pain.
Helewa et al.8 compared four different measures of
abdominal muscle strength in 24 male subjects (12 with low back pain
and 12 without low back pain). The results showed that the subjects
with low back pain had significantly weaker abdominal muscles in three
of the four measures.8 In 1993, Helewa et al. 16
continued their research on the relationship between abdominal
muscle strength, lumbar stabilization, and low back pain.
In this study, three instruments were used to test the strength of
the abdominal muscles: a sphygmomanometer, a vigormeter, and a
myometer. Each of these methods required the subject to perform a
sit-up from supine. The test position was a half sit-up at 45 degrees
of hip flexion, knees at 90 degrees, and feet secured. The
results of the study showed that with all three instruments, the
subjects who proclaimed to have low back pain, also had abdominal
weakness and decreased lumbar stabilization when compared to the
controls.16
This study verified the results Helewa et al.8 found in
their 1990 study.
Suzuki et al.13 investigated the differences in trunk
flexion strength, between 90 males with low back pain and 50 control
subjects. The subjects performed the sit-up from supine while both
isometric and isokinetic measurements were taken. Suzuki et al.13 discovered that the subjects with low back pain had
significantly greater weakness in the abdominal muscles than the
controls, when the abdominal muscles were tested with the legs
extended. The researchers also calculated the percentage
of strength decrements and found that there was a significant amount
of fatigue in the subjects with low back pain as compared to the
controls.13
In addition to the
research indicating that abdominal muscle weakness is associated with
low back pain, there is also considerable literature documenting the
efficacy of low back exercises in the conservative treatment of
chronic low back pain. In 1998, O’Sullivan et al.17
determined that conscious and automatic patterns of abdominal activity
could be altered by specific exercise interventions. Helewa et al.18
compared back exercises and back education programs for patient with
low back pain and found that the incidence of low back pain episodes
were same when comparing the group receiving exercise and back
education to the group receiving exercise only. In 2000,
Taimela et al.19 showed that exercises are beneficial after
guided treatment in the maintenance of the results of a physical
therapy program for low back pain.
Takemasa et al.20 performed a study with the purpose of
examining the differences in trunk muscle strength characteristics and
the effect of trunk muscle exercises on individuals with and without
detectable organic lumbar lesions. The study included 123
subjects with chronic low back pain and 120 control subjects. The
researchers evaluated trunk flexor and extensor muscle strength with
an isokinetic/isometric strength-testing instrument. The subjects were
seated in the device with their knees flexed at 90o, and
their hips flexed at 72o. To determine strength, the
subjects were tested in trunk flexion and extension, both
isometrically and isokinetically. The subjects were first asked to
build up tension until reaching their maximum isometric effort. At
the maximum effort, the subjects were instructed to hold the
contraction for a few seconds, and then repeated the trial after a 15
second rest.20 In the isokinetic testing, the subjects
moved from a range of 40o of trunk flexion, and 20o
of trunk extension at a speed of 60o per second.
Torque and motion angles were measured during the isokinetic testing.
Along with testing the strength, the researchers also evaluated the
patients’ clinical symptoms by using a visual analog scale (VAS) and
the Japanese Orthopaedic Association scores.20 These tools
were used so that the researchers would have a way of evaluating the
effect of strengthening on the patients’ symptoms.
After a baseline measurement was taken, the patients with chronic low
back pain were given a home-exercise program that included
seven-second isometric contractions of the trunk flexors and
extensors, that were to be performed ten times, twice daily. After
approximately three months the patients’ strength was re-evaluated.
The correlation between improvements in low back pain and the increase
in trunk muscle strength was analyzed.
The results showed that the maximum torque per unit of body weight was
significantly lower for the trunk flexors of the subjects with chronic
low back pain, than for the controls.20 Another important
finding was that after exercising for three months, the patients with
chronic low back pain had more significant increases in the strength
of their trunk flexors than the control group. Trunk strengthening
exercises reduced low back pain in both groups, but were more
effective in the group with back pain who had no detectable organic
lesions. The degree of correlation between increased trunk flexor
strength and improvement in low back pain was also higher in this
group. 20 These finding agreed with the results of the
previous studies 8,10,11,12,13,16 that also found that
patients with low back pain have weaker abdominal muscle strength than
control subjects and increasing abdominal strength leads to decreased
low back pain.
The literature supports the existence of a relationship between low
back pain and trunk flexor weakness. Based on this information, it is
important for physical therapists to assess abdominal muscle strength
and its contribution to lumbar spine stabilization in patients with
low back pain. The purpose of this study was to determine whether or
not physical therapists are quantifying abdominal muscle strength
during initial evaluations when the patient’s chief complaint is low
back pain.
Methods
Design
This study utilized a single blind design in the observation of 20
initial low back evaluations. The physical therapists being observed
were blinded to what the researchers were observing during the initial
evaluation. This design was used so that the physical therapist did
not change his or her evaluation techniques during the observation
period. This study was approved by Nova Southeastern University
Internal Review Board.
Subjects
Twenty physical therapists (and their patients) participated in
the study. This was a sample of convenience and consisted of physical
therapists practicing in outpatient sport medicine physical therapy
clinics in South Florida. The clinics selected were those that
routinely treated a large number of patients with low back pain. The
physical therapists were selected to participate in the study if they
had an evaluation scheduled with a patient who met the following
inclusion criteria: (i) at least 18 years of age, (ii) reported
low-back pain that had persisted for greater than one month. Each of
the twenty therapists was observed during one evaluation.
The physical therapists signed an informed consent form. The
explanation of the procedures stated that the researcher would observe
the interaction between the physical therapist and patient during the
initial evaluation. It did not explain that the researcher would be
observing whether the physical therapist was evaluating trunk flexor
strength during the evaluation. The consent form was worded in this
way so that the therapists would not change their normal procedures
for a low back evaluation. Consent to observe the evaluation was also
obtained from the patients.
Procedures
Two physical therapy students collected the data. Prior to data
collection, the students were trained by a physical therapist with
expertise in evaluation and treatment of low back dysfunction on what
assessments would qualify as quantified trunk flexor strength
assessments. A data collection form was developed by the researchers
(See Appendix A). A pilot study was performed where the two students
observed five evaluations together. The results of the two student’s
observations were compared for consistency using the data collection
form and found to be consistent.
During the actual data collection period, the two students
simultaneously recorded whether or not the physical therapists
quantified trunk flexor strength during the initial evaluation of
twenty patients with a primary complaint of low back pain. Each
therapist was observed evaluating one patient. If more than one
physical therapist was observed at the same clinic, there was no
communication among the participating physical therapists until after
all physical therapists had completed the observation period.
Following the observation, each physical therapist was given a
questionnaire and asked to comment on their evaluation of the trunk
flexors. The questionnaire also collected demographic information
about the physical therapists (See Appendix B).
Results
Seven of the twenty (35%) physical
therapists participating in the study were male and 13 of 20 (65%)
were female. Twelve of the twenty (60%) therapists had a Bachelor’s
degree in physical therapy, and 8 of 20 (40%) had an entry level
Master’s degree in physical therapy. The physical therapists varied in
the number of years that they had been practicing physical therapy
(See Figure 1).
Of the 20 initial evaluations
that were observed, 3 of 20 (15%) included objective measures to
quantify trunk flexor strength. Of the 17 out of 20 (85%) that
did not, the two most common reasons given for why the trunk flexors
were not assessed were: 1) the patient was in too much pain, and 2)
abdominal strength or endurance was not a big focus of their initial
evaluation. Other reasons included the following: there was not
enough time during the evaluation, they saw the patient’s strength as
they moved, they forgot, or the patient said that they had weak
abdominal muscles, so there was no need to test the strength or
endurance (See Figure 2). Only 5% of the physical therapists
stated they would quantify trunk flexor strength on the next visit.
Discussion
The majority (85%) of physical therapists observed did not quantify
trunk flexor strength at the initial low back evaluation. Some
physical therapists may feel that assessments of the trunk flexors are
not good measures of a patient’s functional capabilities. The
fact that a patient has good trunk strength does not necessarily mean
the patient can stabilize the lower trunk during a functional
movement. Takemasa et al.,20 Helewa et al.8
and Suzuki et al.,13 confirmed a link between trunk flexor
muscle strength and low back pain. Each of these researchers
found that patients with low back pain had weaker abdominal muscles
than the control subjects without low back pain. The current study
included patients who reported low back pain that had persisted for
over a month, although the researchers did not quantify the level of
pain of the subjects. Further study in this area should include an
objective assessment of the subject’s level of pain.
According to the APTA Guide to Physical Therapy Practice,21
there are 25 categories of tests and measures in Physical Therapy. The
physical therapist selects those tests and measures most appropriate
to the patient's signs, symptoms, and concerns using the clinical
decision-making model. The goals, plan for treatment, and outcomes are
based upon objective findings. Without proper documentation of the
patient’s initial status, the development of intervention plans may be
compromised.22
The literature
suggests that physical therapists may be aware of the relationship
between low back pain and trunk flexor weakness, as evident in their
choices of treatments.15, 17, 19 Research by O’Sullivan
et al.17 and Taimela et al19 have demonstrated
that conscious and automatic patterns of abdominal muscle activation
can be altered by specific exercise interventions and that exercises
are beneficial in the maintenance of the result following active
treatment for recurrent low back pain. Bayramoglu et al.15
demonstrated that abdominal strengthening programs are helpful in
reducing pain in patients with low back pain. Because the literature
suggests this link between low back pain and abdominal muscle
weakness, then it would be beneficial for physical therapists to
quantify trunk flexor strength on the initial evaluation of patient
who present with low back pain. Although this study used a small
sample and a limited geographical area, it suggests that there is a
need for further investigation to determine if physical therapists are
using evidence based practices when selecting assessments and
resultant interventions.
Studies by Nourbakhsh et al.,3 Ashmen
et al.,6 Williams,23 Mellin24 and
Jull at al.,25 have also demonstrated a link between
low back pain and the muscle strength and length in the back
extensors, hip flexors, and hamstrings. Although these evaluation
techniques were not the focus of the observation portion of this
study, further research is needed to determine if physical therapists
are aware of the link between low back pain and the length and
strength of these various muscles and applying their knowledge in a
relevant manner when determining the most appropriate evaluation
techniques and interventions.
The limitations of
this study are that a sample of convenience that was located only in
South Florida was used. In addition, only 20 low back evaluations
were observed. Although this study was a single blinded study, the
physical therapists could have changed their usual evaluation
procedures because they were being observed. It is also possible that
the therapists visually assessed the ability of the patient to
stabilize their trunk but did not quantify and document it.
Future research
should include observation of a greater and more diverse population of
physical therapists from initial evaluation to discharge. Determining
if physical therapists are familiar with the different methods to
quantify trunk strength would be beneficial. Additionally,
investigation into the correlation between trunk weakness and the
inability to stabilize the lumbar spine would provide valuable
information. Further study needs to investigate whether physical
therapists are generically prescribing trunk-strengthening exercises
without objectively assessing the strength to determine the baseline
level of the patient or if these exercises are needed.
Conclusion
The results of
this study demonstrate that physical therapists may not be quantifying
trunk flexor strength during initial low back evaluation sessions.
Further study is needed in this area to determine if this practice is
wide spread and why physical therapists may not be assessing the trunk
stabilizers as part of the evaluation for patients with low back pain.
Appendix A
DATA COLLECTION
INSTRUMENT
1.
Did the physical therapist quantify the strength of the
abdominal muscles during the evaluation?
_______
yes
_______
no
2.
If tested, what technique or instrument did the physical
therapist use to quantify the strength of the abdominal muscles?
_______
Kendall’s MMT technique
_______
Daniel’s and Worthingham’s MMT technique
_______
dynamometer
_______
isokinetic equipment
_______
other___________________________________________________________
Comments:____________________________________________________ |
Appendix B
DEMOGRAPHIC SURVEY
Please answer the following questions.
Place a check where necessary, and answer #6 and #7 in the spaces
provided. Thank you!
1.
Are you _____ male or _____ female?
2.
Physical therapy degree:
______
Bachelor’s degree
______
Master’s degree
______
Doctorate degree
______
Certificate
3.
How many years of physical therapy experience do you have?
______ 0-5
years
______
6-10 years
______
11-15 years
______
16-20 years
______
over 20 years
4.
What is the highest degree that you have earned?
______
Bachelor’s
______
Master’s
______
Doctorate
5.
Did you quantify the abdominal muscle strength, during the
low-back evaluation?
______ yes
______ no
(if Yes,
go to # 6; if No, go to # 7)
6. How
did you quantify the strength of the abdominal muscles (technique
or instrument)?
____________________________________________________________
_______________________________________________________________________
7. Why did you choose not to quantify
the strength of the abdominal muscles during the low-back
evaluation?___________________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
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