Back; Instability Clinical Trial
Official title:
Immediate Effect of Core Stabilization Exercise on Trunk Proprioception in Healthy Individuals: A Feasibility Study
The purposes of this study were to 1) determine test-retest reliability of an iPhone application measurement and protocol, 2) establish minimal detectable change of an iPhone application measurement and protocol, and 3) determine the immediate effect of core stabilization exercise on trunk proprioception in healthy individuals.
This study used a sample of convenience between the ages of 18 - 40. Sixty healthy
participants were recruited by flyers posted in 2 Mahidol university physical therapy
clinics in Pinklao and Salaya, as well as word of mouth from participants and friend. Sample
size calculation was performed using G*Power software (G*Power version 3.1.9.2, University
Kiel, Germany). To our knowledge, no study has investigated the immediate effect of core
stabilization exercise on trunk proprioception neither in healthy individuals, nor patients
with low back pain. However, based on our clinical experiences, we expected to find an
improvement (1-tailed) with a medium effect size (Cohen's d = 0.5); therefore, a total of 60
participants were required at confidence level (α) of .05 and power (1-β) of .80.
Participants who were interested in participation underwent a screening process using
inclusion-exclusion criteria checklist and receive brief information regarding the study. If
they met all inclusion criteria, the consent process was performed. To ensure they
understood the study, they were simply asked regarding the study (i.e. objectives, benefits,
etc.) before signing the consent form.
After the participants provided a written informed consent, all participants filled out the
information sheet for demographic data. After that, they changed their cloth to lab tank top
and shorts to expose only their lower back (L1 to S2). The body landmarks, including lumbar
spine (L1) and sacrum (S2) were identified and marked with a skin pen for iPhone placement.
Each iPhone was placed in the iPhone pocket with transparent film in order to see the iPhone
monitor. The pockets were attached to the participant using a Velcro strap around his/her
trunk and pelvis. These body landmark identification and iPhone placement process was
performed by male or female investigator based upon participant's gender. Once the
participant had completed setting up, the data collection process began.
Participants stood on a drawing paper with feet shoulder width apart. The foot print was
drawn using a marker. This foot print was used for post-test positioning. The participants
stood in a natural stance with arms down by sides. Participants were instructed to stand up
straight and maintain that position for recording lumbar and sacral angles in neutral
position. After recording, participants were instructed to perform 2 set of 3 repetitions of
standing forward bend as far as they can and then return to upright position. Lumbar and
sacral angles at full trunk flexion, as well as lumbar and sacral angles at completion of
returning to upright were recorded for each repetitions. Data for each set were used to
determine test-retest (intra-trial) reliability of an iPhone application, as well as
establish minimal detectable change (intra-trial).
Participants underwent trunk proprioception test (pre-test) process by first performing
practice trials. Participants performed trunk flexion at 30°, 45°, and 60° (4 repetitions
for each degree) with feedback from investigators using those iPhones attached to lumbar
spine and sacrum. This practice trials aimed for participants to get familiar with the
testing protocol, as well as minimize the learning effect. After completion of practice
trials, participants underwent pre-test data collection by perform 3 repetitions of trunk
flexion at randomly selected angles each repetition (30°, 45°, and 60°) without feedback.
Investigators recorded all lumbar and sacral angle data. After completion of pre-test data
collection, all iPhones were removed and body landmarks were erased.
Each participant was randomized into either control or exercise group. Participants in
control group waited for 15 minutes (newspaper and magazines were provided during waiting
period), while participants in exercise group underwent the assessment of core stability in
order to select an appropriate level of core stabilization exercise. After that, each
participants in this group received a 30-minute of core stabilization exercise. Clinically,
physical therapists would prescribe a 30-minute core stabilization exercise program for
patients with non-specific low back pain. This exercise focuses on motor control rather than
strength, endurance, or cardiovascular system.37 It is a low intensity exercise to develop
an ability to automatically control co-contraction of deep abdominal and back muscles during
functional movement. Therefore, the possibility of experiencing muscle fatigue is minimal.
However, the participants were instructed to perform stretching exercise after the data
collection was completed, and perform in following days as well.
Once participants in control group had finished 15-minute rest, and participants in exercise
group had completed core stabilization exercise, they underwent practice trials and
post-test data collection using the same protocol starting with marking all body landmarks.
Data from test (first 2 sets of 3 repetitions) and retest (last 2 sets of 3 repetitions)
from control group were used to determine test-retest (inter-trial) reliability, as well as
derive minimal detectable change (inter-trial) of the protocol. Approximate time of the test
protocol was 45 minutes including 15-minute rest period for the control group, whereas 60
minutes including 30-minute core stabilization exercise for the exercise group.
Rating of perceived exertion (RPE) and heart rate were used to monitor each participant
throughout the protocol to avoid fatigue. Pre- and post-test data from the control and
exercise groups were used to determine the immediate effect of core stabilization exercise.
All Statistical analyses were performed using statistical package for the social science
(SPSS) software (IBM SPSS Statistics for Windows, Version 21.0. Armonk, New York, USA).
Study objective 1 was to determine test-retest reliability of an iPhone application
measurement and protocol. Mean angular displacement data from the iPhone application were
used to calculate test-retest reliability by using intraclass correlation coefficient
(ICC2,k) with confidence intervals. Significance level was held at .05 for all analysis.
Study objective 2 was to establish minimal detectable change (MDC) of measurement. Minimal
detectable change is defined as the smallest amount of change that likely reflects true
change rather than measurement error from the iPhone application and protocol. Study
objective 3 was to determine the immediate effect of a 30-minute core stabilization exercise
on trunk proprioception in healthy individuals. Prior to utilization of statistical tests,
descriptive statistics were performed and statistical assumptions were tested.
Transformation will be performed if the data were not normally distributed. Appropriate
statistical tests (parametric vs. non-parametric) were performed to determine the effects of
30-minute core stabilization exercise on trunk proprioception. Significance level was held
at .05 for all analyses. Post-hoc power analysis was also performed.
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