Immediate Effect of Core Stabilization Exercise on Trunk Proprioception in Healthy Individuals
Condition: Back; Instability
Study type: Interventional

Summary: 
      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.
    

Detailed description: 
      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.
    

Intervention name(s): Lumbar stabilization exercise
Intervention type(s): Other
Intervention description(s): Participants were trained using lumbar stabilization exercise based on their initial lumbar stability level. They were received a 30-minute exercise for 1 session in this study.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Basic Science
Keywords: Position sense; Lumbar stabilization exercise