Effects of Manual Therapy on Shoulder Function
Condition: Musculoskeletal Manipulations; Shoulder; Range of Motion; Muscle Strength; Surface Electromyography
Study type: Interventional

Summary: 
      The purpose of this study is to directly compare the effects of four distinct interventions
      commonly used in the treatment of shoulder pathology on shoulder range of motion (ROM) and
      strength in asymptomatic shoulders:

        -  grade III oscillatory anterior-posterior glenohumeral joint mobilizations

        -  an internal rotation (IR) "sleeper" stretch

        -  supine upper-thoracic manipulation

        -  cervical spine manipulation
    

Detailed description: 
      Research questions:

      Do different interventions result in different immediate changes in shoulder ROM? Ha1:
      Stretching and glenohumeral mobilization will result in increased shoulder ROM Ha2: Thoracic
      and Cervical manipulations will result in decreased shoulder ROM Ho: There will be no
      differences in shoulder ROM between groups for each of the four interventions

      Do different interventions result in different immediate effects for shoulder external
      rotation (ER) strength? Ha1: Stretching and glenohumeral mobilization will result in a
      decrease in ER strength Ha2: Thoracic and cervical manipulations will result in increased ER
      strength Ho: There will be no differences in ER strength between groups for each of the four
      interventions

      Do different interventions result in different immediate effects for shoulder
      electromyographic (EMG) activity? Ha1: Stretching and glenohumeral mobilization will result
      in a decrease in EMG activity Ha2: Thoracic and cervical manipulations will result in
      increased EMG activity Ho: There will be no differences EMG activity between groups for each
      of the four interventions

      Based on pilot data, the apparent effect sizes ranged from .57 - .78. With the ɑ = .05 and
      1-β = .80, G-power software for a 4 group ANOVA yields a sample of 20 participants per group.
      To account for possible sample variations and participant drop-outs, a sample of 24 per group
      will be enrolled. Based on the study design of a randomized cross-over study, where each
      participant will receive two of the interventions, a total sample of 48 individuals will be
      enrolled.

      Once a participant is cleared to participate, all individuals will undergo the following
      tests:

      External Rotator Strength Test Strength of the external rotators (infraspinatus) will be
      measured by a blinded examiner using a hand-held dynamometer (Micro-FET 2, Hoggan Health
      Industries, Salt Lake CIty, UT). The dynamometer will be placed on the high threshold setting
      and the force recorded in Newtons. The strength measurement will be taken with the
      participant in the prone position with their shoulder abducted 90 degrees and 80 degrees of
      external rotation with the elbow bent to 90 degrees. Abduction (ABD) and elbow flexion ROM
      positioning will be assessed using a goniometer, and the shoulder external rotation ROM will
      be measured using the iPhoneX. To ensure consistent placement, the researchers will place a
      mark 10 cm proximal to the medial epicondyle of the humerus. This mark will be aligned with
      the edge of the table in order to allow for adequate clearing of the arm and dynamometer
      while completing the test. A second mark will be placed on the distal end of the radius,
      using the radial styloid process as a reference. The distal edge of the dynamometer will be
      placed at this mark. The testers knee will be positioned behind the participant's elbow to
      ensure there is no compensation and activation of other muscles. At the start of the test the
      participant will be instructed to resist the pressure applied by the tester. The tester will
      apply their force progressively over 5 seconds while the participant maximally resists
      against the dynamometer plate. Two pretest and two post-test measurements of strength will be
      obtained, with the greater measurement used for data analysis.

      Posterior Shoulder Tightness Posterior shoulder tightness (PST) will be measured by blinded
      examiners with the participant side lying with hips and knees flexed to 45 degrees. The
      non-tested humerus will be placed behind the participants head with half of their humerus off
      of the plinth. The participants' arm being tested will be placed so that the humeral condyles
      will be stacked perpendicular to the plinth with the olecranon facing posteriorly in relation
      to the participants' body. The participant's arm will be marked 5cm proximal to the lateral
      epicondyle, where an independent examiner will place the top of the iPhoneX to measure PST in
      degrees. The Level in the Measure application, manufactured by Apple's arkit via iOS 13.2.3,
      will be used to measure horizontal adduction and quantify PST. The tester will be blinded
      from the results of the PST measurement. The arm being tested will be gripped by the tester
      just distal to the humeral condyles. The scapula will be stabilized in retraction throughout
      the test. The test will be completed and the measurement will be recorded when the tester is
      no longer able to stabilize the scapula or the movement ceases. Two trials will be performed
      by the tester with a 10 second rest between trials.

      Internal Rotation ROM Internal rotation range of motion will be measured by a blinded
      examiner with the participant in the prone position, shoulder abducted to 90 degrees, with a
      bolster under the mid-humerus to keep the glenohumeral joint in the neutral position. A mark
      will be placed on the participants arm 5cm distal to the medial epicondyle on the ventral
      forearm where the top of the iPhoneX will be placed to measure internal rotation range of
      motion in degrees. Two testers will be used to complete the test. One tester will apply
      stabilization by placing their elbow atop the scapula, their forearm on top of the
      participant's humerus, and take the participants through the motion. The other tester will
      hold the iPhoneX and record the final measurement. The test will be completed when the
      scapula begins to rise from the table or no further motion is felt. The tester performing the
      motion will be blinded to the measurements being taken. Two trials will be taken on the right
      upper extremity.

      The iPhoneX (iOS 13.2.3) will be used as an inclinometer using the Level in the Measure
      application that is pre-downloaded on the iPhoneX. In this study, the smartphone inclinometer
      application that is available to iPhones for purchase was used.

      EMG of the Infraspinatus Pre-post intervention activity of the infraspinatus muscle will be
      assessed with surface EMG during a maximal voluntary isometric contraction (MVIC). Before
      placing the electrodes on the participants, the area will be thoroughly cleaned with an
      alcohol wipe. A single, Norotrode 20 electrode will then be placed over the muscle belly of
      the infraspinatus. The Delsys EMGworks acquisition software will be used to obtain all EMG
      data. The electrodes will be sampled at a rate of 1926 samples/s. Maximal Voluntary Isometric
      Contraction (MVIC) will be recorded simultaneously with the isometric strength testing. The
      MVC for each participant consists of a 5s hold in the standard manual muscle testing(MMT)
      positioning.

      All EMG data will be prepared and collected by an assessor blinded to the assigned
      intervention, and will be analyzed using the Delsys EMGworks Analysis software.

      Randomization:

      Prior to enrollment, using paired, block randomization, a set of 48 group assignments will be
      prepared and placed in sealed, opaque envelopes by an individual not involved in the data
      collection process.

      The participants will be assigned to two of the four different intervention groups: posterior
      shoulder mobilization, cervical manipulation, thoracic manipulation, and a self-applied
      sleeper stretch technique.

      All participants will select an envelope at the time of enrollment, and only reveal the
      contents to the examiner preforming the intervention. The first intervention will be applied
      at the first research session, and the second intervention will be applied during a second
      session approximately one week later.

      Data Analysis:

      Baseline and participant demographic data will be analyzed and reported using descriptive and
      measures of central tendency.

      Interaction and main effects for Internal rotation ROM, posterior shoulder tightness,
      external rotation force, and infraspinatus EMG activity x intervention will be assessed with
      repeated measures ANOVAs and post hoc testing.
    

Intervention name(s): Thoracic Manipulation; Cervical Manipulation; glenohumeral posterior glide mobilization; Sleeper stretch
Intervention type(s): Other; Other; Other; Other
Intervention description(s): A supine thoracic manipulation will be utilized. Participants will be lying supine on the plinth with their arms crossed over their chest, making sure the forearms are not crossed. An experienced clinician will place their hand on the inferior segment (T4); the superior segment (T3) will be placed in the midrange of thoracic flexion and extension. The clinician will apply a high velocity, end range, anterior to posterior thrust by using their body weight to deliver the thrust through the participants crossed elbows, thus creating a bilateral gapping of the facet joints. If a cavitation is achieved after the first thrust, the thoracic manipulation intervention is complete. If not, one more attempt will be made to achieve a cavitation. Regardless of if there was a cavitation or not, after the second attempt the intervention is complete.; Participants will be lying supine on the plinth on the table. A high velocity low amplitude manipulation will be performed to the cervical spine by an experienced clinician.The clinician will place the right proximal phalanx of the index finger over the posterolateral aspect of the articular pillar at the right C4/C5 segment to maximally influence the C5 myotomal distribution. The clinician's left hand will be cradling the participants head. The participant will be brought into midrange flexion-extension, ipsilateral side bend, and contralateral rotation of C4/5. Once a firm end feel is felt the manipulation will be administered into left rotation in an arc toward the left eye. If a cavitation is achieved after the first thrust, the intervention is complete. If not, one more attempt will be made to achieve a cavitation;after the second attempt the intervention is complete.; Participants will be instructed to lay supine on the plinth and a plastic orthopedic wedge will be placed under their scapula for stabilization on the side that is receiving the mobilization. The experienced clinician will stand on the same side being mobilized and held the participant's arm proximal to the medial and lateral humeral epicondyles. The clinician will hold the participant's arm in the scapular plane, approximately 55 degrees of abduction and slight ER with a grade one long axis distraction applied and sustained throughout the entire mobilization. A grade three oscillatory mobilization will be applied for three sets of 30 seconds with a 30 second rest in between.; Participants will be positioned in a side lying position with the arm to be stretched on the table. The arm to be tested will then be positioned at a 90-90 shoulder abduction and elbow flexion position. A support will be positioned behind the patient to ensure there is no compensatory trunk movement during the stretch, and an examiner verified the arm is in a 90-90 position. A sleeper stretch will be subsequently completed, in which the participant will internally rotate the arm to stretch the posterior shoulder musculature. Three, thirty second stretches will be completed
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: modified crossover, each group will experience 2/4 interventions
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment