A pilot study to determine the effect of one physical therapy session on physical activity levels for individuals with chronic low back pain
A pilot study to determine the effect of one physical therapy session on physical activity levels for individuals with chronic low back pain
Wayne Brewer 0 3
Brian T. Swanson 2
Toni S. Roddey 1
Habeeblai Adewale 4
Caleb Ashmore 4
Jennifer Frerich 4
Cory Perrin 4
Alexis Ortiz 1
0 Texas Woman's University, 6124 Institute of Health Sciences-Houston , 7600 Fannin Street, Houston, TX 77030 , USA
1 Texas Woman's University , Houston, TX , USA
2 University of New England , Portland, ME , USA
3 Texas Woman's University, 6124 Institute of Health Sciences-Houston , 7600 Fannin Street, Houston, TX 77030 , USA
4 Harris Health Systems , Houston, TX , USA
Background: A pilot study was conducted to quantify the effect size of changes in physical activity after of one session of physical therapy for individuals with chronic low back pain and to determine factors that predict daily sedentary activity time. Methods: Fourteen subjects with at least 3 days of physical activity accelerometer data were analyzed before and after one session of physical therapy. Data was analyzed using 1-tailed, paired t-tests with level of significance set at 0.05. Effect sizes were computed using the baseline and post intervention mean differences divided by the baseline and post-intervention differences in the standard deviation. Results: A nonsignificant reduction in steps-per-day and time spent performing sedentary activities, with increases in light and moderate-vigorous physical activity were found (effect size: 0.15-0.33). A nonsignificant decrease in daily sitting and standing time 1 week immediately following the physical therapy session and an increase in daily lying time (p = 0.03) (effect size: 0.23-0.69) were found. Conclusion: One physical therapy session resulted in a small physical activity change for individuals with chronic low back pain. Baseline and post intervention levels of pain catastrophisation and perceptions of disability need to be explored in future studies to determine if these are factors that influence levels of physical activity change for these individuals Results are limited by the small sample size, however the ability to increase physical activity in this population may be of clinical relevance.
Chronic low back pain; Physical activity; Physical therapy
Low back pain (LBP) is a musculoskeletal problem that
will affect approximately 80% of the population at some
point of their lives [
] with an estimated unadjusted
point prevalence ranging from 6.3 to 56.0 percent [
The impairments associated with LBP may progress
to disability if they continue into a chronic state [
Chronic low back pain (CLBP) is often due to
repetitive overuse disorders but can also occur as the result
of a one-time traumatic injury such as a fall or accident
. The continual disability suffered by individuals with
CLBP is multifactorial. Vlayen and Linton noted that the
fear avoidance model may partially explain why CLBP
results in persistent disability for these individuals, due in
part to increased pain catastrophizing and fear of
]. Typically fear leads to hypervigilant behaviors
to protect the individual from engaging in physical
activities that are perceived as threatening [
]. The result is
the avoidance of necessary physical movements, normally
used to perform instrumental activities of daily living. It
was hypothesized that this lack of daily movement may
lead to a continual cycle of elevated fear, catastrophizing,
perceptions of disability, physical disuse and pain [
Physical therapy (PT) is an integral component for the
functional recovery of individuals with CLBP.
Restoration of muscular strength, flexibility, spinal mobility and
cardiovascular endurance are typically included in PT
regimens designed to improve the function of individuals
with CLBP [
]. Often these treatment programs are based
on movement classification systems that attempt to
categorized patients into distinct treatment paradigms such
as: centralization/directional preference exercise,
stabilization exercise, traction or manipulation based on factors
including: the chronicity of the injury, presence of
peripheral neurological symptoms, pain location, and
provocation factors [
]. In practice, there are many instances
where the patients’ classification is unclear and has a
non-specific pathoanatomical etiology that is hallmarked
by recurrence of symptoms that often is debilitating .
Non-specific low back pain may be addressed with more
than one treatment paradigm. A previous study by [
found that only 50% of patients fit the described
categories, with 25% fitting more than one category, and 25%
not fitting any of the defined treatment classifications.
This classification may be particularly difficult in
individuals with longer duration of LBP [
]. Despite the
lack of evidence for a standardized exercise prescription
for individuals with CLBP, the use of progressive graded
exercise has been shown to increase physical activity
]. No published studies have examined if physical
activity patterns are altered after one session of exercise
training for individuals with CLBP.
Spinal manipulation has been shown to have mild to
moderate short-term improvements on perceptions of
pain and disability that can occur after one treatment
]. The proposed rationales for these
improvements include a wide range of effects, such as
neurophysiological changes, increased segmental joint mobility, and
placebo effects from the procedure [
]. Despite these
reported benefits, spinal manipulation, which has been
shown to be highly effective for individuals with acute
low back pain, appears to be less effective for
individuals with subacute and chronic low back pain [
8, 14, 16
However, previous studies that have assessed the
effectiveness of spinal manipulations used subjective reports
of pain and self-perceived levels of disability [
impact of spinal manipulation on objective measures of
physical activity is not clear when performed on a CLBP
There are a multitude of patient misconceptions
regarding the effectiveness of diagnostic and treatment
modalities that are utilized in the medical model such as
advanced imaging, opiate use,
analgesic/anti-inflammatory injections and surgical procedures [
documented evidence for any of these diagnostic and
treatment interventions is lacking and frequently these
procedures are palliative in nature [
education is considered to be of paramount
importance for individuals with CLBP [
]. Patient education
delivered in the context of PT interventions typically
focuses on three key areas: (1) addressing the fear
avoidant behaviors displayed by the patient; (2) informing the
patient regarding basic pain science principles; and (3)
applying cognitive behavioral approaches such as graded
activity and graded exposure programs to promote
confrontation with the perceived threat to the patient’s
6, 13, 22
]. These educational methods are often
combined with biomechanical principles to promote safe
activity performance to prevent re-exacerbation of
symptoms. Patient education that utilize cognitive behavioral
approaches are often combined with other interventions
and are dispersed over several treatment sessions that use
patient self-perceptions of pain and disability as the
outcomes studied [
]. To date, there are no studies
that examined if there are immediate changes in physical
activity patterns for individuals who receive an initial
session of PT that is comprised of patient education.
Despite the myriad of rehabilitative and medical
interventions used to address the pain, impairments and
resultant disabilities for individuals with CLBP, the
documented effectiveness for any one treatment paradigm is
]. CLBP is often viewed as recalcitrant to
1, 8, 20, 28
]. Most published studies
utilize self-perceptions of pain and disability as the primary
]. Others use the aforementioned measures
combined with physical performance measures such as
walking tests, handgrip strength, muscular strength and
spinal mobility assessments [
]. While there are
published studies that examine the levels of physical
activities (PA) for these patients using reliable methods for PA
monitoring such as accelerometry, the majority of these
studies have occurred outside the clinical environment
]. Accelerometry uses small devices worn on the
hip or wrist that measure movement, change of
position, steps per day and energy expenditure for a given
time period [
]. The accuracy of accelerometers far
exceeds self-reported questionnaires of PA which often
suffer threats to validity such as recall bias [
When assessed via accelerometer, studies suggest
that there are no differences in levels of physical
activity between individuals who have chronic pain when
compared to healthy, age-matched controls [
]. It is
difficult to determine from these studies if the subjects
had increased levels of fear avoidance, pain
catastrophisation or self-perceptions of disability, however most of
these studies were cross-sectional in design. There is a
dearth of literature that examines short term changes in
objectively measured PA when physical therapy
interventions, particularly spinal manipulations, exercise and
patient education are administered to these individuals.
Studies are needed to quantify if there is an effect of these
commonly used physical therapy interventions on
freeliving physical activity for individuals with CLBP.
Freeliving physical activity is defined as “the level of activity
that the patients, within their physical limitations, at
their own pace, and in their own environment, typically
A pilot study was conducted to examine the effects of
physical therapy interventions for individuals with CLBP
based on the aim to quantify the short-term effects of one
PT session that included spinal manipulations, exercise
and patient education on free-living PA in individuals
with CLBP. This combination of interventions represents
a “typical” initial physical therapy session of individuals
with CLBP. We hypothesize that the additive effects of
each intervention will have the capacity to have an
immediate increase in free-living physical activity. The purpose
of this pilot study was to determine effect sizes that may
be used to establish sample sizes for future studies that
investigate the efficacy of physical therapy interventions
to increase physical activity in persons with CLBP.
Subjects were recruited from a publicly funded,
hospitalbased outpatient physical therapy clinic. The inclusion
criteria were: (1) patient referral to outpatient PT with a
CLBP related diagnosis; (2) CLBP without radiating pain
distally to the knee > 3 months in duration; (3) ability to
read and write in English or Spanish; and (4) between the
ages of 18 and 70 years old; (5) able to ambulate
independently without assistive devices. Subjects were excluded
if they had: (1) previously been diagnosed via
radiography or clinical exam with spinal instability, fracture or
tumor; (2) a clinical indication of nerve root pathology;
(3) previous spinal surgery; (4) a diagnosis of
osteoporosis or rheumatoid arthritis; (5) used oral steroids within
the previous 6 months; (6) a workman’s compensation or
disability claim filed for a previous low back injury; (7)
self-report of current or suspected pregnancy; and (8)
presented with incomplete accelerometer data. All
subjects completed an informed consent document prior to
enrollment into the study that was approved by the
Institutional Review Board of Texas Woman’s University and
Harris Health Systems.
Physical activity Triaxial accelerometers [GT3XP-BTLE;
Actigraph, LLC., FL, USA] were used to measure the
physical activity level of the subjects at a frequency of
30 Hz. This is a small device with dimensions that are
4.6 cm × 3.3 cm × 1.5 cm, that weighs 19 g. The
inclinometer within these accelerometers was also activated
to measure time spent in sitting, standing or
recumbent postures. The accelerometers were activated within
the Actilife software [v6.0; Actigraph, FL, USA] using
each subject’s weight, height, race/ethnicity, sex, date of
birth, and hand dominance. The means of the following
parameters were the variables of interest for this study:
(1) number of steps taken each day; (2) mean
percentage of the day spent performing sedentary (SED) [(0–99
counts), light (LHT) (100–1951 counts),
moderate-tovigorous physical activity (MVPA) (≥ 1952 counts) each
day; 3] mean percentage of the day spent in the standing,
lying and sitting positions. The Actigraph accelerometer
has excellent reliability and validity with other methods
for assessing energy expenditures across varied levels
of physical activity [
]. The subjects were instructed to
wear the accelerometer on the right hip during their
waking hours for at least 8 h for a period of 7 days. Instances
where the accelerometer did not reach values higher than
zero counts within a 10-min epoch were considered as
non-wear time. If the data for each subject did not reach
the pre-established wear time of at least 3-days, then
the data for this subject was removed from the analysis.
Therefore, in order to consider data valid for analysis,
each subject needed to have at least 5 h/day of wear time
for at least 3 days during the 7-day period, regardless of
whether the days were consecutive or not. Three days of
accelerometry data has been suggested in other studies
to be the minimal wear time to reliably capture
physical activity patterns in adults [
]. The percentage
of time spent performing SED, LHT and MVPA per day
were calculated with the Freedson 1998 algorithms [
Six physical therapists participated in this study. Their
clinical experience ranged from 2 to 8 years. All of them
received advanced training in orthopedic manual
physical therapy with a patient caseload comprised of
approximately 90–95% orthopedic disorders with approximately
50% of those patients referred to physical therapy with
low back pain. Patients were referred to the outpatient
physical therapy clinic to be evaluated for their primary
complaint of low back pain. During this process, eligibility
for inclusion into the study was assessed by the physical
therapist assigned to the patient. If the patient was found
eligible for inclusion in the study, he or she was invited
to participate in the study; all patients who accepted the
invitation then completed the informed consent process.
The first session included data collection only, with no
treatment intervention conducted during this session. To
obtain baseline data, each subject was asked to wear the
accelerometer for the next seven consecutive days for at
least 8 h/day. Each subject was scheduled for their first
treatment session one week after the initial evaluation to
allow for one full week of PA data capture utilizing the
accelerometer. At the first treatment session, the
accelerometer was retrieved and the data downloaded onto a
designated research computer via ActiLife® software. To
ensure adequate retrieval of the accelerometer, subjects
who missed the first treatment session were either called
or emailed to reschedule the appointment. Subjects who
returned for the first treatment session without the
accelerometer were asked to bring it to the next treatment
session; the data was analyzed using only the initial 7 days
from the day of issue. If a subject did not: (1) return the
accelerometer; (2) return it with adequate data; (3) return
for a scheduled physical therapy session; and (4) respond
to the text, email or phone messages, then the patient was
considered lost to follow-up.
The physical therapy intervention was based on a
previously published clinical guideline on the management of
low back pain [
]. The physical therapy intervention
consisted of one treatment session that included a
manipulation technique(s) to either the sacroiliac joint, thoracic,
or lumbar spine. The manual therapy interventions are
described below and pictures and descriptions of the
manual therapy interventions can be found in Additional
file 1: Appendix S1.
1. Thoracic gapping manipulation: a high-velocity, low
amplitude end-range technique was delivered using
an anterior–posterior directed thrust at the mid and
lower thoracic spine using the patient’s crossed arms
and flexed elbows.
2. Lumbopelvic gapping manipulation: a
high-velocity, low-amplitude end-range thrust technique was
delivered using an anterior-inferior directed thrust
applied to the flexed lumbar spine in a side-lying
3. Lumbopelvic unilateral gapping mobilizations: a mid
to end-range, non-thrust mobilization technique
applied to lumbar spine in side-lying using an
anterior-lateral directed force with the individual’s cranial
4. Hip long-axis distraction manipulation: a
high-velocity, end-range thrust technique applied in an axial
direction through the distal lower extremity to the
flexed, abducted and slightly externally-rotated hip
joint in supine.
Each subject was instructed on an exercise program
based on the clinical judgement of the physical therapist
that are classified as motor control exercises,
transversus abdominis training, lumbar multifidus training, and
dynamic lumbar stabilization exercises based on the
published clinical guidelines by [
]. The primary exercises
included were: (1) quadruped heel rocks, supine
abdominal brace and bent knee fallout exercises to enhance
motor control, recruitment of the transversus abdominis
and multifidi; (2) chair stands, seated hip hinge, bridging
were used to promote dynamic lumbar stabilization
during functional movements. The pictures and descriptions
of the exercises can be found in Additional file 1:
Appendix S2. The sequence of how the manual therapy and
exercise interventions were administered can be found in
Additional file 1: Appendix S3.
These exercises were performed at the first treatment
session and each patient was instructed in a home
exercise program to promote increased segmental mobility
and stability of the lumbar spine. Each subject performed
a submaximal aerobic endurance exercise on either a
bicycle, treadmill or elliptical trainer with the duration
and intensity set at a moderate intensity level based on
the effort that was verbally given to the therapist. Patient
education was provided which consisted of techniques to
promote self-management of his or her CLBP condition
via cognitive behavioral approaches such as graded
exercise, graded exposure or basic pain science information
to minimize the hypervigilant behaviors such as
restriction of certain activities [
12, 13, 21
]. At the conclusion of
the first treatment session, each participant was issued
the accelerometer for a second time and instructed to
wear the device in a similar fashion for another 7 day
period. Each subject was asked to return the
accelerometer at their next treatment session, scheduled 7 days later.
The means and standard deviations (SD) for the following
physical activity variables derived from the accelerometer
were computed: number of steps taken each day,
percentage of the day spent performing SED, LHT and MVPA
per day (counts/day) and the percentage of the day spent
in the sitting, lying and standing positions. Descriptive
variables such as the mean age, height, weight, BMI and
gender of the study participants were calculated. Cohen’s
d was calculated to determine the baseline and post
intervention effect size for the variables previously listed
using the formula below:
Mean(baseline) − Mean(post − intervention)
The aim of this pilot study was to determine the effect
size of one physical therapy session on physical activity
levels, one-tailed paired t-tests were performed with the
level of significance set at 0.05 determine if significant
differences were found between the baseline and
postintervention means for the aforementioned variables.
One-tailed level of significance supports the hypothesis
that the one session intervention will promote a decrease
in the SED activities while promoting an increase in
LHT and MVPA. Twenty-seven subjects were needed to
achieve 80% power based on an a priori analysis using an
effect size of 0.50 for 0.05 level of significance using
onetail. The effect size used for the power analysis was based
on a systematic review published by Keller et al. that
examined the effects of interventions performed on
individuals with chronic low back pain using self-perceptions
of pain and function as the outcomes [
]. They reported
pooled effect sizes of 0.57, 0.52 and 0.35 for
behavioral interventions, exercise training and manipulation,
Thirty subjects were screened for eligibility, with 27
subjects fully enrolled. After screening for validity of the
accelerometer data, a total of 14 subjects’ accelerometer,
self-report and physical performance measures were
analyzed (Fig. 1).
The 13 subjects that were not included in the
analysis did not meet the required wear time of the
accelerometer as previously discussed. There were 11 females
and 3 males (7 African-Americans, 6 Hispanic, 1
Caucasian); the mean age and BMI was 50.2 years, 31.6 kg/
m2, respectively. The physical activity measures and wear
time of the accelerometer at baseline and post
intervention are presented in Table 1.
There was a trend towards reduction in the number
of steps taken per day and the time spent performing
30 subjects were recruited and screened to determine eligibility
27 subjects met the eligibility criteria and were enrolled in the study
13 subjects completed the study but were subsequently dropped
from further analysis due to incomplete accelerometer data
14 subjects’ accelerometer, self-report questionnaires and physical
performance data was analyzed.
Fig. 1 Consort diagram of flow of subjects in the study
SED activities, with concurrent increases in LHT and
MVPA. These findings presented with small effect sizes
that ranged from 0.33 and.16 for the percentage increase
in time spent performing LHT and MVPA, respectively.
The paired t-tests revealed no post-intervention
significant differences from baseline in physical activity levels
(Table 1). A nonsignificant decrease in percentage of the
day was spent sitting and standing during the 1 week
immediately following the physical therapy session, with
a concurrent significant increase in the percentage of the
day spent lying (p = 0.03). The baseline to
post-intervention effect sizes for the percentage of time spent in each
position were small to medium and ranged from 0.23 to
0.69 (Table 1).
The purpose of this pilot study was to determine the
effect size that one session of PT has on physical
activity. This pilot study showed that one session of PT that
included spinal manipulation, exercise and patient
education had a trend towards increasing physical activity
for individuals with chronic low back pain. There was a
small effect of reducing the percentage of time spent
performing SED activities with a similar effect of increasing
time spent performing light physical activities.
Paradoxically, the percentage of time spent lying increased while
the time spent standing and sitting decreased.
Researchers that conduct studies that examine the
impact that PT has on free-living physical activities need
to carefully consider their aims of their study to be
adequately powered. If the aim of their study is to determine
the impact that PT has on reducing time spent
performing SED and increasing LHT physical activities for
individuals with CLBP then the sample size requirements
are approximately four times less than studies that seek
adequate power to detect changes in MVPA. Despite
MVPA being touted as the level of activity needed to
promote health, studies that examine changes in this
type of behavior must have the resources needed to
support a large number of subjects to detect small changes
in this behavior. It is evident that this drastic difference
in sample size requirements stems from the fact that for
individuals with CLBP, the majority of the time is spent
performing SED activities which provides researchers a
larger opportunity to study the effects of interventions to
shift these individuals’ physical activity levels towards the
There are several limitations of the study that
warrant discussion. The extremely small sample size
limits the ability to make inferences to a larger population.
This study was underpowered due to non-compliance
with accelerometer wear time. Despite the increased
risk of bias, the power analysis was based on previous
effect sizes determined for pain and self-perceptions
of function, which are variables not considered for this
study. Because this is the first study to examine changes
in physical activity levels after one physical therapy
session, there were no established effect sizes that could be
used to directly determine the sample size to be
sufficiently powered. The subjects in this study were primarily
female, whose ethnic backgrounds were predominately
African-American or Hispanic, and who were seeking
physical therapy services at a publicly-funded outpatient
clinic. Previous studies suggest that leisure-time
physical activity patterns tend to be lower for: men compared
to women, minorities compared to Caucasians, and
individuals with lower as compared to those of higher
socioeconomic status [
]. The results in this
population may not be consistent with those observed in other
populations. Lastly, causation would have been more
evident with the addition of a control group using a mixed
between and within subjects design, however the present
design did allow for each subject to be his or her own
control. Future studies that examine the impact of
physical therapy on physical activities patterns need to utilize
larger, more ethnically diverse sample sizes with
individuals of varied socioeconomic levels with longer follow-up
There have been numerous studies that have examined
the short-term effects of physical therapy
interventions on the understanding of pain neurophysiology,
self-reported pain, disability and biomechanics. To our
knowledge, this is the first study to determine the effect
size of a single physical therapy session that includes
exercise, patient education and spinal manipulation on
changes in physical activity profiles for individuals with
CLBP. The generation of these effects sizes will allow
future researchers to determine adequate sample sizes
needed to answer additional research questions regarding
the impact of physical therapy on physical activity. A
comprehensive physical therapy program results in a small
effect to increase the level of physical activity in
individuals with CLBP as soon as the first treatment session.
Additional file 1: Appendix S1. Lumbopelvic manipulation techniques.
Additional file 2: Appendix S2. Lumbar stabilization and range of
motion exercise program.
Additional file 3: Appendix S3. Physical therapy treatment sequence.
LBP: low back pain; CLB: chronic low back pain; PT: physical therapy; PA:
physical activity; SED: sedentary; LHT: light; MVPA: moderate–vigorous physical
WB: provided the initial conceptual design, drafted the manuscript, secured
the data collection site and funding to conduct the study. BS and TR: provided
initial and revised conceptual design, review and substantial revision of
the manuscript, composed the background and methods section of the
manuscript. HA, CA, JF, CP: provided data acquisition, implemented the
study procedures, recruitment of subjects, composed the study intervention
description of the methods section of the manuscript, provided manuscript
review, provided pictures at the data collection sites. AO: provided initial and
revised conceptual design, data analysis, composed the accelerometry data
acquisition process under the methods section of the manuscript, manuscript
revision and interpretation of accelerometry data in the discussion section of
the manuscript. All authors read and approved the final manuscript.
The authors would like to thank Dr. Dana Tew, manager of outpatient
rehabilitation services and Dr. Christopher Dewey, director of rehabilitation services of
Harris Health, Quentin Mease Rehabilitation Hospital for providing managerial
and administrative support for this project.
The authors declare that they have no competing interests.
Availability of data and materials
The datasets during and/or analyzed during the current study available from
the corresponding author on reasonable request.
Consent for publication
Ethics approval and consent to participate
All subjects who participated in this study gave prior written and verbal
consent. Ethical approval for the study procedures were obtained from Texas
Woman’s University Institutional Review Board (Protocol: 17852).
This study was supported by grant funds furnished by the Texas Woman’s
University Research Enhancement Program (11.410.10.1221.00002264).
Funding to publish this study was provided by the Texas Woman’s
University Library Open Access Fund.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
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