Corticospinal Excitability of Deep Back and Abdominal Muscles
Condition: Instability; Back; Tightness of Back Muscles
Study type: Interventional

Summary: 
      This study aims to understand the roles of corticospinal excitability in controlling the
      trunk movement, and the clinical utility of clinical observation, as well as the effect of
      lumbopelvic stabilization during hamstrings muscle stretching.
    

Detailed description: 
      This study will use a sample of convenience between the ages of 20 and 40. Subjects with and
      without history of low back pain will be recruited by flyers posted in university physical
      therapy clinics in 2 locations, as well as word of mouth from subjects and friends. Subjects
      who are interested in participation will undergo a screening process using
      inclusion-exclusion criteria checklist and receive brief information regarding the study. If
      the participants meet all inclusion criteria, the consent process will be performed. To
      ensure the participants understand the study, the participants will be simply asked regarding
      the study (i.e. objectives, benefits, etc.) before signing the consent form. Total data
      collection including intervention between pre- and post-intervention will take approximately
      2 hours.

      After obtaining the written informed consent, all participants will fill out the information
      sheet for demographic data. Participant will have the right to refuse answering the
      demographic questionnaire, but the participants can participate in biomechanical data
      collection. Then, participants will asked to remove the metal accessories that could
      influence the electromagnetic field, change the cloth to lab tank top and shorts to expose
      the lower back and right knee, and wear the shoes throughout the test protocol. The body
      landmarks will be identified. These landmarks include 1) lumbar spine level 1 (L1), 2) sacrum
      level 2 (S2), 3) lateral epicondyle of right (RE) and left (LE) knees, and 4) head of fibula
      of right (RF) and left (LF) leg. These locations will be used to place motion sensors for
      outcome measures. The preparation process will take approximately 10 minutes.

      The subjects will stand in a natural stance with arms down by sides. The participants will be
      instructed to perform functional movements including active forward bend, right and left
      straight leg raise tests, right and left hip abduction with knee flexion tests, quadruped
      backward rock test, prone with right and left knee flexion tests, prone with right and left
      hip internal/external rotation tests, prone with right and left hip extension tests. Each
      subject performs 2 trials of 3 consecutive repetitions of each functional movement tests.
      Heart rate and rating of perceive exertion (RPE) will be monitored after each functional
      movement tests. Two physical therapists (PT-A and PT-B), who are blinded to the group
      membership, will simultaneously observe and independently rate aberrant movement patterns.
      After physical therapists completing the clinical observation, the participants will hand the
      rating form to the principal investigator to input into a spreadsheet for further analysis.
      These data will be used to determine inter-rater reliability and diagnostic accuracy of
      clinical observation of aberrant movement patterns during functional movements to identify
      individuals with a history of CLI. The clinical observation will take about 20 minutes.

      Prior to performing SLR, motion sensors will be placed on the subject's body landmarks.
      Subjects will be asked to perform one repetition of active forward bend, while motion data
      are simultaneously collected. Then, subjects will be asked to lay on the treatment table in
      supine position. PT-A will perform passive SLR, and maximal angle will be recorded. This SLR
      test is intended to determine whether the subject has a sign of CLI, rather than to assess
      neural tension (to rule out HNP and dural tension) or hamstrings muscle length. In
      participants with clinical lumbar instability, pelvis/hip will not be stabilized when
      performing passive SLR. In this case, when pelvis/hip has reached its restriction by
      hamstrings muscle tightness, lumbar spine would easily allow compensatory motion. Thus, leg
      raising greater than 91° would indicate clinical lumbar instability. This test is differed
      from hamstrings muscle tightness (passive knee extension in supine with 90° hip flexion
      position). This test the clinician will fix the pelvic/hip at 90°; therefore, compensatory
      motion from pelvis/hip will be minimized. After that, PT-A will perform hamstrings muscle
      length test. Subjects will be first asked to lay on the treatment table with tested hip and
      knee in 90 degrees flexion. PT-A will passively extend subject's knee to maximal tolerable
      point. Angle in sagittal plane between lateral epicondyle and head of fibula sensors will be
      measured to represent hamstrings muscle length. PT-A will perform additional clinical
      examination including modified Thomas test (muscle length test for iliopsoas, quadriceps, hip
      abductor, and hip adductor muscles), Ober's test (muscle length test for tensor fascia latae
      muscle), as well as abdominal and back muscle strength test assessed by a handheld
      dynamometer. These outcome measures will be assessed for baseline. To reduce the risk of
      muscle fatigue, the investigators will monitor heart rate and verbally ask the RPE during the
      test, and provide adequate resting period between repetitions. The clinical examination will
      take approximately 10 minutes.

      After clinical data collection, the subjects will undergo corticospinal excitability
      measurement using transcranial magnetic stimulation (TMS). The investigator will identify
      transversus abdominis muscle (2 cm medial and 2 cm inferior to anterior superior iliac spine
      on the inguinal line), and lumbar multifidus muscle (2 cm lateral to lumbar spinous process
      of level 4). These locations will be used for EMG electrode placement. Before placing surface
      EMG electrodes, the skin will be lightly abraded using abrasive paper and cleaned using
      cotton with alcohol to lower the skin impedance. Electrodes will be aligned parallel to the
      muscle fibers. Then, Subjects will be seated comfortably in a reclined chair with both arms
      supported. The participants will be asked to wear a swim cap used to identify stimulation
      areas for transverse abdominis and lumbar multifidus muscles. The investigator will use a
      double cone coil to find the hotspot for both ipsilateral and contralateral to the pain in
      each muscle. Figure 1 illustrates TMS set up. After corticospinal excitability measurement,
      subjects will be randomly assigned into 2 groups (lumbopelvic stabilization, LPS and
      lumbopelvic relaxation, LPR). The TMS data collection will take approximately 60 minutes.

      The subjects in both groups will perform hamstrings muscle stretching in standing position.
      The participants will be asked to place the heel on the tested leg on the compression load
      cell mounted on the adjustable treatment table. The adjustable treatment table will be
      initially set at the subject's knee level. Treatment table will gradually move up until force
      at the heel reaches 15% of the body weight. This standardized force will be controlled by the
      compression load cell. Our preliminary study indicates that 15% of the body weight is the
      maximal stretching force in which subjects have reported very hard level of exertion (16-18
      out of 20) on RPE during stretching exercise. During applying stretching force, subjects in
      LPS will be asked to keep the lumbar and pelvic positions as rigid as possible without
      holding the breath, while subjects in LPR will be asked to relax the lumbopelvic region and
      do not hold against stretching force. Each subject will perform 4 repetitions of 30-second
      stretching with 15 seconds rest between repetitions.

      After the intervention, the subjects will be reassessed for lumbopelvic motion during forward
      bend and hamstrings muscle length test. The intervention and reassessment process will take
      approximately 20 minutes. The data at baseline and post-intervention will be used to
      determine the effect of lumbopelvic stabilization during hamstring muscle stretching in
      individuals with and without a history of CLI. In addition, the investigator will call each
      subject for 1-year follow up to check whether subjects have any episode of low back pain and
      how often the participants have low back pain.
    

Intervention name(s): Lumbopelvic stiffening technique; Lumbopelvic relaxing technique
Intervention type(s): Other; Other
Intervention description(s): Participants will stretch the hamstrings muscle in standing position with lumbopelvic stiffening technique. Fifteen percent of the body weight will be used to standardize stretching force. During stretching protocol, the participants will be instructed to face the hydraulic table with the hips square, maintain trunk straight up and look straight ahead. Researcher commands "during adjusting the bed up, please tense the back rigid". After that, hydraulic bed will be lifted up until force reaches 15 percent of the body weight. Participant will perform 30 seconds/repetition for 4 repetitions with 15 seconds rest between repetitions.; Participants will be instructed to face the hydraulic table with the hips square, maintain trunk straight up and look straight ahead. The researcher commands "During adjusting the bed up, please relax the back". The hydraulic bed will be lifted up until force reaches 15 percent of the body weight. Participant will perform 30 seconds/repetition for 4 repetitions with 15 seconds rest between repetitions.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Participants will be randomly assigned to either stretching exercise with lumbopelvic stiffening technique or lumbopelvic relaxing technique. They will be provided a 2-day wash-out period. Then, participants will cross-over to another technique.
Masking: Double (Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Clinical lumbar instability; History of low back pain; Corticospinal excitability; Stretching exercise; Movement system impairment