Effects of Different Verbal Instructions in Healthy Adults and Patients With Low Back Pain
Effects of Different Verbal Instructions in Healthy Adults and Patients With Low Back Pain
Segmental stabilization exercise has been shown to be effective in the rehabilitation of low
 back pain (LBP). Due to the isometric nature of segmental stabilization exercise, manual
 therapists use various verbal instructions to elicit lumbar multifidus muscle contraction.
 The purpose of this study was to assess whether or not three verbal instructions would alter
 muscle thickness of the lumbar multifidus differently in asymptomatic individuals and
 patients with LBP.

 Three verbal instructions were selected for this study: (1) swell the muscle underneath the
 transducer, (2) draw your belly button in towards your spinal column, and (3) think about
 tilting your pelvis but without really doing it. Lumbar multifidus muscle thickness was
 determined using parasagittal ultrasound imaging. Measurements of muscle thickness were
 collected at rest and during verbal instructions from 21 asymptomatic adults and 21 patients
 with LBP. Percent changes of muscle thickness during contraction and at rest were compared
 between groups and across verbal instructions.
Participants:

 Eligible participants were English-speaking adults 18 years of age or older. Additional
 criteria for asymptomatic healthy adults included no existing low back pain (LBP) and no LBP
 in the past year. Additional criteria for patient participants included existing LBP near the
 L5-S1 level with an average pain intensity score ≥ 2/10 (numeric pain rating scale of 0-10, 0
 being no pain, 10 being unbearable pain).

 Exclusion criteria for all participants included previous low back surgery, systemic joint
 disease (e.g. rheumatoid arthritis), cancer of the lower quadrant, neurological disorders,
 allergic reaction to ultrasound gel, or inability to obtain testing positions (prone lying).

 After participants were informed of the risks, benefits and procedures of the study, they
 were asked to sign a written consent form approved by the TWU Institutional Review Board -
 Dallas. Eligible participants were asked to complete an intake form, asking them about their
 age, gender, and past medical history. For participants with existing LBP, they were asked
 about their pain location, duration, intensity, and nature of their existing LBP and their
 LBP history. The height and body weight of each participant were taken to determine the body
 mass index (BMI). BMI has been shown to be a factor affecting muscle size.

 Instrumentation:

 1. The Modified Oswestry Low Back Pain Index (OSW) questionnaire was used to determine an
 individual's perceived disability and function limitation due to his/her low back pain.
 The OSW questionnaire has been shown to be reliable and valid.

 2. A Sonosite M-Turbo ultrasound scanner (Sonosite, Inc., Bothell, WA) was used to measure
 muscle size of the lumbar multifidus. A curvilinear transducer (3-5 MHz) will be used to
 take transverse images of segmental lumbar multifidus at the L5-S1 segment. If the
 patient has multiple painful segments, the most painful segment will be imaged. The most
 common painful segments are L4-5 or L5-S1 in patients with LBP.

 3. The ImageJ software (free download from the NIH website) was used to determine muscle
 thickness off-line.

 US Image Acquisition:

 Participants was lying in prone on an examination table with their arms on the sides. A
 pillow was placed under the participant's abdomen to flatten the lumbar lordotic curve and an
 inclinometer was placed on the lumbosacral junction to ensure the lumbar curve ≤10.

 The right side of asymptomatic healthy adults and the painful side of patients with low back
 pain were imaged. The spinous processes of the right L5-S1 or the painful segment were
 identified by palpation and marked with an erasable pen. Next, the spinous process was
 verified using US imaging. Transverse images of the segmental multifidus muscle were captured
 by placing the transducer horizontally on the spinous process of the target segment. The
 transverse image of segmental lumbar multifidus was taken 3 times "at rest" and 3 times
 during muscle activations of the lumbar multifidus. Activation of lumbar multifidus was
 achieved by asking participants to generate a slow gentle sustained (isometric) contraction
 of the lumbar multifidus using 3 different verbal instructions without moving their spine or
 pelvis. Participants held each contraction for 3-5 seconds. The order of 3 verbal
 instructions was given in a random order to minimize the learning and fatigue effects.
 Therefore, each participant performed a total of 9 lumbar multifidus muscle contractions
 during each testing session. Prior to taking ultrasound images, the anatomy and location of
 the lumbar multifidus muscle were explained and shown to participants using a model and
 pictures. Next, the following 3 verbal instructions were used to generate a multifidus
 contraction:

 Breathe in and out and:

 1. Without moving your spine, try to "swell" the muscle underneath the transducer.

 2. Without moving your spine, draw your spinal column in toward your belly button.

 3. Attempt to elongate your spine by drawing the muscles in your back up toward your head.

 All participants were asked to return one week later, the procedure was repeated. The order
 of verbal instructions also was randomized in the 2nd session.
Inclusion Criteria:

 -  additional criteria for asymptomatic healthy adults include no existing LBP and no LBP
 in the past year.

 -  additional criteria for patient participants include existing LBP near the L5-S1 level
 with an average pain intensity score ≥ 2/10 (numeric pain rating scale of 0-10, 0
 being no pain, 10 being unbearable pain).

 Exclusion Criteria:

 -  previous low back surgery,

 -  systemic joint disease (e.g. rheumatoid arthritis),

 -  cancer of the lower quadrant,

 -  neurological disorders,

 -  allergic reaction to ultrasound gel, or

 -  inability to obtain testing positions (prone lying).