Do maximal isometric trunk tasks produce maximum activity in latissimus dorsi?

Introduction: Electromyography (EMG) studies investigating latissimus dorsi activity during trunk tasks have reported high activation levels and described latissimus dorsi as an important contributor to trunk movement and stability. However, the normalisation of EMG data in these studies is inconsistent with some normalising to shoulder tasks and a majority normalising to trunk tasks. Therefore, this study aimed to compare commonly used shoulder and trunk normalisation tasks to determine if trunk tasks produce maximum activity in latissimus dorsi.

Arthroscopic capsular shift surgery in patients with atraumatic shoulder joint instability: a randomised, placebo-controlled trial.

Objectives: To determine the effect of arthroscopic capsular shift surgery on pain and functional impairment for people with atraumatic shoulder (glenohumeral) joint instability.

Methods: We conducted a randomised, placebo-controlled clinical trial in a specialist secondary care facility. Patients aged 18 years and over who reported insecurity (apprehension) in their shoulder joint and had evidence of capsulolabral damage on arthroscopic examination were included.

Analysis of phase detects altered timing of muscle activation in subjects with chronic shoulder pain.

Optimal exercise therapy for shoulder pain is unknown due to limited information regarding specific changes in muscle function associated with pain. Timing of muscle activity with respect to movement (phase) can provide information about muscle activation patterns without requiring electromyography data normalization which is problematic in the presence of pain. The aim of this study was to determine if a phase measure is able to detect differences in the timing of shoulder muscle activation in subjects with chronic shoulder pain.

Acute experimentally-induced pain replicates the distribution but not the quality or behaviour of clinical appendicular musculoskeletal pain. A systematic review.

Objectives: Experimental pain is a commonly used method to draw conclusions about the motor response to clinical musculoskeletal pain. A systematic review was performed to determine if current models of acute experimental pain validly replicate the clinical experience of appendicular musculoskeletal pain with respect to the distribution and quality of pain and the pain response to provocation testing.

Methods: A structured search of Medline, Scopus and Embase databases was conducted from database inception to August 2020 using the following key terms: "experimental muscle pain" OR "experimental pain" OR "pain induced" OR "induced pain" OR "muscle hyperalgesia" OR ("Pain model" AND "muscle").

Motor Imagery Performance and Tactile Spatial Acuity: Are They Altered in People with Frozen Shoulder?

Frozen shoulder (adhesive capsulitis) is a severe chronic pain condition that is not well understood and current treatment is suboptimal. In several other chronic pain conditions motor imagery and tactile acuity deficits are present, which are thought to represent associated neuroplastic changes. The aims of this study were to determine if motor imagery performance assessed by the left/right judgement task, and tactile acuity assessed by two-point discrimination, are altered in people with unilateral frozen shoulder.

Measurement properties of translated versions of the Shoulder Pain and Disability Index: A systematic review.

Purpose: To summarise measurement properties of translated versions of the Shoulder Pain and Disability Index (SPADI) and to assess their methodological quality.

Methods: Relevant studies testing measurement properties of translated versions of the SPADI in non-specific shoulder pain participants were included from 11 databases (August 2020). Two reviewers independently screened articles and assessed individual measurement property risk of bias using the COSMIN checklist as very good, adequate, doubtful or inadequate.

Do surface electrodes validly represent lower trapezius activation patterns during shoulder tasks?

Because of its superficial location, surface electrodes are commonly used to record lower trapezius activity. Recent evidence, however, would suggest that surface electromyography is not a valid to record activity from other superficially placed shoulder muscles. Therefore, the aim of this study was to determine the validity of using surface electrodes to record lower trapezius activity.

Is implicit motor imagery altered in people with shoulder pain? The shoulder left/right judgement task.

Background: Implicit motor imagery performance is altered in a variety of chronic pain conditions, but it is not known whether this is the case in shoulder pain.

Objectives: The aim of this study was to assess implicit motor imagery performance, using a valid and reliable shoulder left/right judgement task in people with shoulder pain.

Design: Cross-sectional observational study.

Is the Normal Shoulder Rotation Strength Ratio Altered in Elite Swimmers?

Introduction: It is commonly believed that the shoulder external rotation (ER) to internal rotation (IR) strength ratio is decreased in swimmers due to predominant IR loading during the pull-through (propulsive) phase which predisposes to shoulder pain. However, the evidence supporting this hypothesis is inconclusive. Therefore, the aim of this study was to examine shoulder rotation strength parameters in elite swimmers and investigate potential associations with shoulder pain.

Experimental shoulder pain models do not validly replicate the clinical experience of shoulder pain.

Background and aims People with shoulder pain often present with abnormal shoulder muscle function. It is not known whether shoulder pain causes or is the result of muscle dysfunction. If pain leads to muscle dysfunction, therapeutic interventions that produce shoulder pain may be contraindicated.

Shoulder extension strength: a potential risk factor for shoulder pain in young swimmers?

Objectives: To determine the relationship and predictive value of isometric shoulder strength in the development of shoulder pain in young swimmers.

Design: Prospective, cohort study.

Methods: Shoulder flexion, extension, external and internal rotation strength tests were performed in elevation on 85 swimmers (14-20 years; 48 females) without current shoulder pain using a hand-held dynamometer.

Do People With Chronic Musculoskeletal Pain Have Impaired Motor Imagery? A Meta-analytical Systematic Review of the Left/Right Judgment Task.

The left/right judgment task (LRJT) is the most commonly used method of assessing motor imagery performance. Abnormally long response times are thought to reflect delayed processing of body/spatial representations, and poor accuracy is thought to reflect disrupted cortical proprioceptive representations or body schema. Slower and less accurate responses on the LRJT have been reported in a variety of chronic musculoskeletal pain conditions.

Scapular upward rotation position is symmetrical in swimmers without current shoulder pain.

Objectives: A history of shoulder pain is common in swimmers and may influence scapular position, possibly increasing the risk of shoulder pain recurring. The aim of this study was to establish and compare bilateral static measures of scapular upward rotation in swimmers (14-20 years), some with a history of shoulder pain but all currently pain free, in two different elevated positions of shoulder abduction.

Design: Cross-sectional, observational study.

Isometric shoulder strength in young swimmers.

Objectives: The prevalence of shoulder pain in young swimmers is high. Shoulder rotation strength and the ratio of internal to external rotation strength have been reported as potential modifiable risk factors associated with shoulder pain. However, relative strength measures in elevated positions, which include flexion and extension, have not been established for the young swimmer.

Shoulder muscle activation patterns and levels differ between open and closed-chain abduction.

Objectives: Open and closed-chain abduction of the shoulder are commonly used in rehabilitation and exercise programs to assess and/or improve shoulder muscle function. However, it is not known if shoulder muscle activation patterns differ between these two exercises. Therefore the purpose of this study was to compare muscle activation patterns during closed-chain shoulder abduction performed using a shoulder press machine with open-chain abduction using free weights.

The development of a shoulder specific left/right judgement task: Validity & reliability.

Background: Disruption of cortically-held working body schema has been associated with a variety of pain conditions. A motor imagery technique - the left right judgement task (LRJT) - has been used as an indirect assessment of the integrity of the working body schema. To date there is no LRJT specifically designed to investigate the body schema of persons with shoulder pain.

Is subscapularis recruited in a similar manner during shoulder internal rotation exercises and belly press and lift off tests?

Objectives: Although the belly press and lift off tests are recommended to assess subscapularis function, shoulder internal rotation (IR) exercises performed in other shoulder positions are more commonly used to restore subscapularis function. It is not known if shoulder IR exercises specifically activate subscapularis to the same degree as the lift off and belly press tests, and thus have the potential to effect subscapularis strength gains. Therefore, the aim was to compare subscapularis activation levels with those of other shoulder internal rotator muscles during the belly press and lift off tests and shoulder IR exercise positions.

Humeral torsion and shoulder rotation range of motion parameters in elite swimmers.

Objectives: Optimal shoulder rotation range of motion (ROM) for swimming is unknown. The primary aim of this study was to examine shoulder rotation ROM in elite swimmers, including the influence of humeral torsion on rotation ROM, in order to establish optimal shoulder rotation parameters for swimming. In addition, we examined the relationship between rotation ROM and shoulder pain.

Does load influence shoulder muscle recruitment patterns during scapular plane abduction?

Objectives: Load is used to increasingly challenge muscle function and has been shown to increase muscle activity levels with no change in activation patterns during shoulder flexion, extension, adduction and rotation. However, the effect of load during shoulder abduction, a movement commonly used in assessment of shoulder dysfunction and to improve shoulder function, has not been comprehensively examined. Therefore, the purpose of this study was to determine if load influences shoulder muscle activation patterns and levels during scapular plane abduction in normal subjects.

The Reliability of Strength Tests Performed In Elevated Shoulder Positions Using a Handheld Dynamometer.

Context: The reliable measurement of shoulder strength is important when assessing athletes involved in overhead activities. Swimmers' shoulders are subject to repetitive humeral elevation and consequently have a high risk of developing movement-control issues and pain. Shoulder-strength tests performed in positions of elevation assist with the detection of strength deficits that may affect injury and performance.

Does changing the plane of abduction influence shoulder muscle recruitment patterns in healthy individuals?

Study Design: Observational laboratory study.

Background: Abduction is a movement commonly used in the assessment of shoulder dysfunction and prescription of exercises to improve shoulder function. Abduction in the scapular and coronal planes are used interchangeably.

Does surgery followed by physiotherapy improve short and long term outcome for patients with atraumatic shoulder instability compared with physiotherapy alone? - protocol for a randomized controlled clinical trial.

Background: Shoulder instability is a common problem affecting young adults. Stabilization surgery followed by physiotherapy rehabilitation has been shown to reduce the chance of further episodes of shoulder dislocation and to improve quality of life in patients who sustain a shoulder dislocation as a result of a high collision trauma, but it is unclear if surgical intervention is beneficial for patients with atraumatic shoulder instability who have structural damage at the shoulder. The aim of this randomized controlled clinical trial is to determine if the addition of surgical intervention to physiotherapy rehabilitation improves outcomes for patients with atraumatic shoulder instability who have sustained soft tissue damage at their joint.

Do surface electrode recordings validly represent latissimus dorsi activation patterns during shoulder tasks?

Because of its superficial location surface electrodes are commonly used to record latissimus dorsi (LD) activity. Despite the fact that the recommended electrode placement is over the belly where LD is quite thin no studies have investigated the possibility of signal contamination from muscles lying deep to LD. Therefore, the aim of this study was to determine the validity of using surface electrodes to record activity from LD.