Rehabilitation Exercises for Dysfunction of the Scapula: Exploration of Muscle Activity Using Fine-Wire EMG.

BACKGROUND: Scapular muscle activity during shoulder exercises has been explored with surface electromyography (EMG). However, knowledge about the activity of deeper-layer scapular muscles is still limited. PURPOSE: To investigate EMG activation of the deeper-layer scapular stabilizers (levator scapulae [LS], rhomboid major [RM], pectoralis minor [Pm] muscles) together with superficial muscle activity (upper [UT], middle [MT], and lower trapezius [LT] and serratus anterior [SA]) during 4 exercises often used for training scapular function. Based on the amplitude EMG of the deeper-layer muscles, scapular muscle activation ratios for the 4 exercises were calculated, hereby providing knowledge of the optimal muscle balance. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 26 healthy participants performed 4 shoulder exercises (side-lying external rotation [ER], side-lying forward flexion, prone horizontal abduction with ER, and prone extension) while simultaneously measuring scapular muscle activity. Intramuscular electrodes were used for the deeper layer, in contrast to surface electrodes for the superficial muscles. All data were normalized to percentage of maximal voluntary isometric contraction (%MVIC), and the activation ratios (the muscle activity of the deeper layer relative to the other muscles) were calculated. A 1-way analysis of variance with Bonferroni correction was applied for statistical analysis. RESULTS: Moderate activity was found in all exercises for the LS and RM (25%-45% MVIC). The Pm resulted in low activity during both side-lying exercises (13%-18% MVIC). Ratios involving LS or RM showed values >1 for all exercises (1.28-12.41) except for LS/MT, LS/LT, and LS/RM (0.85-0.98) during side-lying ER, and LS/MT, RM/MT and RM/LS (0.85-0.99) during side-lying forward flexion. Likewise, values <1 were found when MT (0.85) and LS (0.99) were involved with RM in the numerator during side-lying forward flexion. Ratios with Pm in the numerator showed values <1, apart from the ratios with UT and SA in the denominator. CONCLUSION: The study provides extended knowledge about the deeper-layer scapular muscle activity and related ratios during the 4 shoulder exercises mentioned here. Putting theory into practice, based on our results, we advise both side-lying exercises to be performed to strengthen LT and MT, even in case of hyperactivity of the Pm. However, the 4 exercises should be given carefully to patients with hyperactivity in the LS and/or RM. CLINICAL RELEVANCE: The findings of this study may assist clinical decision making in exercise selection for restoring scapular function.

Effect of Plyometric Training on Sport Performance in Adolescent Overhead Athletes: A Systematic Review.

CONTEXT: Plyometric training has been shown to be beneficial in adolescent overhead athletes. However, existing research on the effects of plyometrics on sport performance has been limited. OBJECTIVE: To systematically review the current literature to investigate whether plyometric training intervention improves upper- and lower-body sport performance. DATA SOURCES: Two electronic databases (MEDLINE and Web of Science) were searched using specific Medical Subject Headings (MeSH) terms up to February 2019, and hand-searching was performed by looking to relevant studies that were cited in other studies. STUDY SELECTION: A total of 932 items were identified and were further assessed for the eligibility in the systematic review. For a study to be eligible, each of the following inclusion criteria had to be met: (1) participants were aged 13 to 18 years and selected from a sports or athletic population and the study (2) involved the evaluation of a plyometric training intervention with an aim to improve sports performance; (3) must have included a control intervention and/or control group; (4) included a quantitative objective measure of sport performance variables concerning throwing, jumping, running, and sprinting; and (5) was published in English. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 3. DATA EXTRACTION: A first screening was conducted based on title and abstract of the articles. In the second screening, the full text of the remaining articles was evaluated for the fulfillment of the inclusion criteria. RESULTS: A total of 14 studies were included in this review. The methodological quality of the included studies ranged from low to moderate. There is moderate evidence that plyometric training intervention improves throwing and jumping performances. There is also preliminary evidence that plyometric training intervention improves sprint performance. CONCLUSION: The current evidence suggests that sport performance consisting of throwing capacity, jumping ability, and sprint performance significantly improved due to plyometric training interventions in adolescent overhead athletes.

Muscle activity and scapular kinematics in individuals with multidirectional shoulder instability: A systematic review.

BACKGROUND: Several studies reported the importance of glenohumeral and scapular muscle activity and scapular kinematics in multidirectional shoulder instability (MDI), yet a systematic overview is currently lacking. OBJECTIVE: This systematic review evaluates and summarizes the evidence regarding muscle activity and shoulder kinematics in individuals with MDI compared to healthy controls. METHOD: The electronic databases PubMed and Web of Science were searched in September 2020 with key words regarding MDI (population), muscle activity, and glenohumeral and scapular movement patterns (outcomes). All studies that compared muscle activity or scapular kinematics between shoulders with MDI and healthy shoulders were eligible for this review, except for case reports and case series. All articles were screened on the title and abstract, and remaining eligible articles were screened on full text. The risk of bias of included articles was assessed by a checklist for case-control data, as advised by the Cochrane collaboration. RESULTS: After full text screening, 12 articles remained for inclusion and one study was obtained by hand search. According to the guidelines of the Dutch Institute for Healthcare Improvement, most studies were of moderate methodological quality. We found moderate evidence that MDI individuals show increased or prolonged activity of several rotator cuff muscles that control and centre the humeral head. Furthermore, we found evidence of decreased and/or shortened activity of muscles that move or accelerate the arm and shoulder girdle as well as increased and/or lengthened activity of muscles that decelerate the arm and shoulder girdle. The most consistent kinematic finding was that MDI individuals show significantly less upward rotation and more internal rotation of the scapula during elevation of the arm in the scapular plane as compared with controls. Finally, several studies also suggest that the humeral head demonstrates increased translations relative to the glenoid surface. CONCLUSION: There is moderate evidence for altered muscle activity and altered humeral and scapular kinematics in MDI individuals as compared with controls.

Analysis of Scapular Kinematics and Muscle Activity by Use of Fine-Wire Electrodes During Shoulder Exercises.

BACKGROUND: During nonoperative or postoperative rehabilitation after sports injuries, exercise selection is often based on minimal load on the injured/repaired glenohumeral structures, while optimally activating scapulothoracic muscles. Previous research explored scapular muscle activity during rehabilitation exercises using surface electromyography (EMG). However, limited information exists about the deeper lying muscle activity, measured with fine-wire electrodes, even more in combination with 3-dimensional scapular kinematics. PURPOSE: To report scapular kinematics synchronously with surface and fine-wire EMG during specific shoulder exercises for early rehabilitation. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 23 healthy male patients were recruited. Three-dimensional scapular kinematics were measured combined with EMG recording of 8 muscles during 4 commonly used shoulder exercises (inferior glide, low row, lawnmower, and robbery). Upper (UT), middle (MT), and lower (LT) trapezius and serratus anterior muscle activities were measured with bipolar surface electrodes. Intramuscular electrodes were placed in the levator scapulae (LS), rhomboid major (RM), pectoralis minor (Pm), and infraspinatus (IS) muscles. All data were normalized as a percentage of maximal voluntary isometric contraction (%MVIC). A linear mixed model with Bonferroni correction was applied for statistical analysis. RESULTS: Scapular kinematics revealed an anterior tilt position during the inferior glide, low row, and robbery (P < .05). An upward rotation position between 20° and 30° was reached in all exercises except low row. Inferior glide (31°) and low row (42°) represented a significantly increased internal rotation position compared with lawnmower and robbery. Lawnmower and robbery showed significantly (P < .05) more MT (lawnmower, 36% MVIC; robbery, 39% MVIC) and RM (lawnmower, 59% MVIC; robbery, 66% MVIC) activation compared with inferior glide and low row. Lawnmower and robbery showed significantly (P < .05) less Pm activation (9.5%-12% MVIC). LS was significantly more active during robbery (58% MVIC) compared with inferior glide and low row (27%-36% MVIC) (P < .05). IS showed moderate activity (24%-37% MVIC) for all exercises, except low row (13% MVIC). CONCLUSION/CLINICAL RELEVANCE: This study provides new insights about scapular positions and activation of the deeper layer muscles during 4 commonly used shoulder rehabilitation exercises. The lawnmower showed a favorable position of the scapula with less Pm activity in contrast to the low row. The inferior glide, lawnmower, and robbery should not be implemented in early phases of shoulder rehabilitation because of their moderate muscle activity.

Does scapular corrective taping alter periscapular muscle activity and 3-dimensional scapular kinematics? A systematic review.

STUDY DESIGN: This is a systematic review. INTRODUCTION: Scapular taping is widely used in the management of scapular dysfunction. However, its effects on the scapular kinematics and the electromyography (EMG) activity of the periscapular muscles are not clear. PURPOSE OF THE STUDY: The purpose of the study was to systematically review the current literature to examine whether scapular corrective taping alters the EMG activity of the periscapular muscles and the 3-dimensional scapular kinematics. METHOD: MEDLINE and Web of Science databases were searched using specific mesh terms up to April 2018. A hand search was also conducted on the reference list of the included articles. A total of 157 studies were identified, and they were further analyzed for the eligibility to the systematic review. Studies that investigated the effects of scapular corrective taping on the EMG activity of the periscapular muscles and on the 3-dimensional scapular kinematics on patients with shoulder problems or asymptomatic subjects were eligible for the systematic review. The Cochrane Effective Practice and Organization of Care criteria were modified and used for the risk-of-bias assessment. RESULTS: Eleven articles met the inclusion criteria and were included in the systematic review. Five studies investigated the effects of corrective taping on the scapular kinematics and 8 studies reported the effects of corrective taping on the EMG activity of the periscapular muscles. There was an agreement among the studies that scapular upward rotation is increased with the corrective taping, while there are inconsistent results concerning the scapular external rotation and posterior tilt. In addition, studies mostly reported that corrective taping decreases the activity of the upper trapezius, while it has conflicting effects on the activity patterns of other periscapular muscles. DISCUSSION: Scapular corrective taping was found to increase the scapular upward rotation; however, its effects on scapular external rotation and posterior tilt are controversial. It was also found that corrective taping might decrease the EMG activity of the upper trapezius, while it had no effects on the activity of lower trapezius, and its effects on other periscapular muscles were controversial. CONCLUSION: The results of the studies indicated that scapular corrective taping might alter the 3-dimensional scapular kinematics, while there are controversies about the effects of corrective taping on the EMG activity of the periscapular muscles. Further studies are needed to clarify the conflicts.

Diet-induced weight loss alone or combined with exercise in overweight or obese people with knee osteoarthritis: A systematic review and meta-analysis.

OBJECTIVES: The purposes were to (i) determine the effect of diet-only treatments and combined diet and exercise treatments on pain and physical function and (ii) explore the effect of these treatments on inflammatory biomarkers in overweight and obese adults with knee osteoarthritis. METHODS: Five electronic databases were searched until March 2017. Randomised controlled trials investigating the effect of non-surgical non-pharmacological weight loss treatment, with or without exercise, on self-reported pain and/or physical function and/or inflammatory biomarkers were selected. Two review authors independently extracted data and assessed risk of bias for each study. Standardised mean differences (SMD) of outcomes were pooled as appropriate, using a random effects approach. RESULTS: 2676 articles were identified, 19 met review criteria and 9 met criteria for meta-analyses. Diet-only treatments did not reduce pain (SMD -0.13; 95% confidence interval, CI: -0.37, 0.10; I2 = 49%) while a combination of diet and exercise treatments did reduce pain moderately (SMD -0.37; 95%CI: -0.69, -0.04; I2 = 54%). Physical function improved moderately with diet treatments (SMD -0.30; 95%CI: -0.52, -0.08; I2 = 47%) and combined diet and exercise treatments (SMD -0.32; 95%CI: -0.56, -0.08; I2 = 24%). Of the inflammatory markers assessed, only IL-6 reduced with diet-only treatments (SMD -0.23; 95%CI: -0.45, -0.02; I2 = 0%). CONCLUSION: Overall, moderate pain-relief is achievable with a combination of diet and exercise, but potentially not with diet-only treatments. Findings support that either diet-only treatments or combined diet and exercise treatments moderately improve physical function. Overall, treatment effects on inflammatory biomarkers are questionable.

The impact of different lenses on visual and musculoskeletal complaints in VDU workers with work-related neck complaints: a randomized controlled trial.

OBJECTIVES: The impact of wearing lenses on visual and musculoskeletal complaints in VDU workers is currently unknown. The goal of this study was 1) to evaluate the impact of wearing VDU lenses on visual fatigue and self-reported neck pain and disability, compared to progressive lenses, and 2) to measure the effect of both lenses on head inclination and pressure pain thresholds during the performance of a VDU task. METHODS: Thirty-five eligible subjects were randomly assigned to wear progressive VDU lenses (VDU group) (n = 18) or progressive lenses (P group) (n = 17). They were enquired about visual complaints (VFQ), self-perceived pain (NRS) and disability (NDI) at baseline (with old lenses), and 1 week, 3 months and 6 months after wearing their new lenses. In addition, Forward Head Angle (FHA) and PPTs were assessed during and after a VDU task before and 6 months after wearing the new lenses. A short questionnaire concerning the satisfaction about the study lenses was completed at the end of the study. RESULTS: In both groups, visual fatigue and neck pain was decreased at 3 and 6 months follow up, compared to baseline. All PPTs were higher during the second VDU task, independent of the type of lenses. The VDU group reported a significantly higher suitability of the lenses for VDU work. CONCLUSION: It can be concluded that there is little difference in effect of the different lenses on visual and musculoskeletal comfort. Lenses should be adjusted to the task-specific needs and habits of the participant.

The isokinetic rotator cuff strength ratios in overhead athletes: Assessment and exercise effect.

OBJECTIVE: Muscle strength imbalance in the shoulder region can be considered as a predisposing factor in the development of movement dysfunctions, possibly leading to overuse injuries. Repetitive overhead throwing, performed in sports, may result in muscle imbalance between the external (ER) and internal (IR) rotators. Muscle strength measured with an isokinetic device, is reported as a concentric (CON) or eccentric (ECC) force. The balance between an agonist and an antagonist is mentioned as a ratio (CON/CON or ECC/CON). The aim of this systematic literature review is to provide an overview of the existing evidence considering the isokinetic muscle strength ratios of ER and IR of the shoulder in healthy overhead athletes. In addition, the effect of exercise programs on these ratios was investigated. METHODS: Two online databases (Web of Science and PubMed) were consulted using different search strategies. Articles were selected based on inclusion and exclusion criteria. All included articles were assessed on their methodological quality. RESULTS AND CONCLUSIONS: There is moderate evidence for a lower functional deceleration ratio (ECC ER/CON IR) at the dominant side. This lower ratio is due to a large overweight of CON IR strength on that side. There is no consensus about which exercise program is the most effective in altering the shoulder isokinetic strength ratios.

Scapular muscle dysfunction associated with subacromial pain syndrome.

STUDY DESIGN: Narrative Review. INTRODUCTION: One of the shoulder pain disorders in which the function of the scapula is comprised is the subacromial pain syndrome. Several rehabilitation guidelines and exercises have been proposed to improve scapulothoracic muscle dysfunction. Consideration of muscle activation patterns may help to select the most appropriate rehabilitation exercise in these patients. To date, suggesting rehabilitation exercises is often based upon the knowledge of the superficial lying scapulothoracic muscles' activity. In the assumption that the deeper lying scapulothoracic muscles' activity may hinder normal scapular movement in case of tightness or hyperactivity, exercise protocols for patients with altered pattern in scapulothoracic muscles should also integrate knowledge on the deeper lying scapulothoracic muscle activity. PURPOSE OF THE STUDY: To help clinicians choosing the most appropriate exercise in patients with subacromial pain syndrome related to scapulothoracic muscle dysfunction. METHODS: First, a summary of key alterations in scapulothoracic (muscle) function in patients with subacromial pain was accomplished. Second, promising practical rehabilitation strategies toward restoring scapulothoracic muscle dysfunction (with a focus on scapulothoracic exercises) were developed, integrating current new research evidence (including information about the deeper lying scapulothoracic muscles) with clinical practice. CONCLUSION: This review details clinical exercises and their muscular activity to guide clinicians to optimize individualized scapulothoracic training and treatment programs by selecting the most appropriate exercise, based on knowledge from the clinical examination. LEVEL OF EVIDENCE: Level 5.

The influence of induced shoulder muscle pain on rotator cuff and scapulothoracic muscle activity during elevation of the arm.

BACKGROUND: Altered recruitment of rotator cuff and scapulothoracic muscles has been identified in patients with subacromial impingement syndrome. To date, however, the cause-consequence relationship between pain and altered muscle recruitment has not been fully unraveled. METHODS: The effect of experimental shoulder pain induced by injection of hypertonic saline in the supraspinatus on the activity of the supraspinatus, infraspinatus, subscapularis, trapezius, and serratus anterior activity was investigated during the performance of an elevation task by use of muscle functional magnetic resonance imaging in 25 healthy individuals. Measurements were taken at 4 levels (C6-C7, T2-T3, T3-T4, and T6-T7) at rest and after the elevation task performed without and with experimental shoulder pain. RESULTS: During arm elevation, experimentally induced pain caused a significant activity reduction, expressed as reduction in T2 shift of the IS (P = .029). No significant changes in T2 shift values were found for the other rotator cuff muscles or the scapulothoracic muscles. CONCLUSIONS: This study demonstrates that acute experimental shoulder pain has an inhibitory effect on the activity of the IS during arm elevation. Acute experimental shoulder pain did not seem to influence the scapulothoracic muscle activity significantly. The findings suggest that rotator cuff muscle function (infraspinatus) should be a consideration in the early management of patients with shoulder pain.

Comparing Trigger Point Dry Needling and Manual Pressure Technique for the Management of Myofascial Neck/Shoulder Pain: A Randomized Clinical Trial.

OBJECTIVE: The aim of this study was to investigate short-term and long-term treatment effects of dry needling (DN) and manual pressure (MP) technique with the primary goal of determining if DN has better effects on disability, pain, and muscle characteristics in treating myofascial neck/shoulder pain in women. METHODS: In this randomized clinical trial, 42 female office workers with myofascial neck/shoulder pain were randomly allocated to either a DN or MP group and received 4 treatments. They were evaluated with the Neck Disability Index, general numeric rating scale, pressure pain threshold, and muscle characteristics before and after treatment. For each outcome parameter, a linear mixed-model analysis was applied to reveal group-by-time interaction effects or main effects for the factor "time." RESULTS: No significant differences were found between DN and MP. In both groups, significant improvement in the Neck Disability Index was observed after 4 treatments and 3 months (P < .001); the general numerical rating scale also significantly decreased after 3 months. After the 4-week treatment program, there was a significant improvement in pain pressure threshold, muscle elasticity, and stiffness. CONCLUSION: Both treatment techniques lead to short-term and long-term treatment effects. Dry needling was found to be no more effective than MP in the treatment of myofascial neck/shoulder pain.

Are chronic neck pain, scapular dyskinesis and altered scapulothoracic muscle activity interrelated?: A case-control study with surface and fine-wire EMG.

OBJECTIVES: The function of the scapula is important in normal neck function and might be disturbed in patients with neck pain. The surrounding muscular system is important for the function of the scapula. To date, it is not clear if patients with idiopathic neck pain show altered activity of these scapulothoracic muscles. Therefore, the objective of this study was to investigate differences in deeper and superficial lying scapulothoracic muscle activity between patients with idiopathic neck pain and healthy controls during arm elevation, and to identify the influence of scapular dyskinesis on muscle activity. METHODS: Scapular dyskinesis was rated with the yes/no method. The deeper lying (Levator Scapulae, Pectoralis Minor (Pm) and Rhomboid major) and superficial lying (Trapezius and Serratus Anterior) scapulothoracic muscles' activity was investigated with fine-wire and surface EMG, respectively, in 19 female subjects with idiopathic neck pain (age 28.3±10.1years, average duration of neck pain 45.6±36.3months) and 19 female healthy control subjects (age 29.3±11.7years) while performing scaption and towel wall slide. Possible interactions or differences between subject groups, scapular dyskinesis groups or phases of the task were studied with a linear mixed model. RESULTS: Higher Pm activity during the towel wallslide (p=0.024, mean difference 8.8±3.3% MVIC) was shown in patients with idiopathic neck pain in comparison with healthy controls. For the MT, a significant group∗dyskinesis interaction effect was found during scaption which revealed that patients with neck pain and scapular dyskinesis showed lower Middle Trapezius (MT) activity in comparison with healthy controls with scapular dyskinesis (p=0.029, mean difference 5.1±2.2% MVIC). CONCLUSIONS: In the presence of idiopathic neck pain, higher Pm activity during the towel wallslide was found. Patients with neck pain and scapular dyskinesis showed lower MT activity in comparison with healthy controls with scapular dyskinesis during scaption. Scapular dyskinesis did not have a significant influence on scapulothoracic muscle activity.

Scapulothoracic muscle activity during elevation exercises measured with surface and fine wire EMG: A comparative study between patients with subacromial impingement syndrome and healthy controls.

BACKGROUND: The quality of the scapular movement depends on the coordinated activity of the surrounding scapulothoracic muscles. Besides the well-known changes in Trapezius and Serratus Anterior (SA) activity in patients with subacromial impingement syndrome (SIS), no studies exist that have investigated the activity of the smaller less superficial muscles that attach on the scapula (Pectoralis Minor (Pm), the Levator Scapulae (LS) and the Rhomboid Major (RM)) in a population with SIS, despite the hypothesized importance of these muscles in shoulder function. OBJECTIVES: To investigate if patients with shoulder impingement syndrome (SIS) show differences in deeper and superficial lying scapulothoracic muscle activity in comparison with a healthy control group during arm elevation tasks. STUDY DESIGN: Controlled laboratory study. METHODS: Activity of the deeper lying (LS, Pm and RM) and superficial lying scapulothoracic muscles (Trapezius and SA) was investigated with fine-wire and surface electromyography (EMG) in 17 subjects with SIS and 20 healthy subjects while performing 3 elevation tasks: scaption, wall slide and elevation with external rotation. Possible differences between the groups were studied with a linear mixed model (factor "group" and "exercise"). RESULTS: For the Pm only, a significant main effect for "Group" was found: during the elevation exercises, the Pm was significantly more active in the SIS group in comparison with the healthy controls. CONCLUSION: Patients with SIS show significantly higher Pm activity during elevation tasks in comparison with healthy controls. This study supports the idea of a possible role of the Pm in SIS.

Superficial and Deep Scapulothoracic Muscle Electromyographic Activity During Elevation Exercises in the Scapular Plane.

STUDY DESIGN: Controlled laboratory study. BACKGROUND: In scapular rehabilitation training, exercises that include a humeral elevation component in the scapular plane are commonly implemented. While performing humeral elevation, the scapula plays an important role, as it has to create a stable basis for the glenohumeral joint. However, a comparison of both deep and superficial muscle activity of the scapula between different types of elevation exercises is lacking and would be helpful for the clinician in choosing exercises. OBJECTIVES: To evaluate scapulothoracic muscle activity during different types of elevation exercises in the scapular plane. METHODS: Scapulothoracic muscle activity was measured in 21 healthy subjects, using fine-wire electromyography in the levator scapulae, pectoralis minor, and rhomboid major muscles and surface electromyography in the upper trapezius, middle trapezius, lower trapezius, and serratus anterior muscles. Measurements were conducted while the participants performed the following elevation tasks in the scapular plane: scaption (elevation in the scapular plane), towel wall slide, and elevation with external rotation (Thera-Band). The exercises were performed without and with additional load. Possible differences between the exercises and the load were studied with a linear mixed model. RESULTS: Performing elevation in the scapular plane with an external-rotation component resulted in higher middle trapezius and lower trapezius activity compared to the scaption and wall slide exercises. The upper trapezius was maximally activated during scaption. The pectoralis minor and serratus anterior showed the highest activity during the towel wall slide. The towel wall slide activated the retractors to a lesser degree (middle trapezius, lower trapezius, levator scapulae, rhomboid major). Adding load resulted in higher muscle activity in all muscles, with some muscles showing a different activation pattern between the elevation exercises, depending on the load condition. CONCLUSION: Scaption maximally activated the upper trapezius. The addition of an extra external-rotation component may be used when the goal is to activate the lower trapezius and middle trapezius. The towel wall slide exercise was found to increase pectoralis minor activity. Adding load resulted in higher muscle activity. Some muscles showed a different activation pattern between the elevation exercises, depending on the loading condition. The findings of this study give information about which elevation exercises a clinician can choose when the aim is to facilitate specific muscle scapulothoracic activity.

Serratus anterior or pectoralis minor: Which muscle has the upper hand during protraction exercises?

BACKGROUND: The Serratus Anterior (SA) has a critical role in stabilizing the scapula against the thorax. Research has linked shoulder and neck disorders to impairments in the SA activation. Exercises that target the SA are included in the rehabilitation of shoulder or neck pain and mostly include a protraction component. The Pectoralis Minor (PM) functions as a synergist of the SA. From the literature it is unclear to what extent PM is activated during SA exercises. OBJECTIVES: To determine the activity of SA and PM during different protraction exercises. DESIGN: Controlled laboratory study. METHOD: 26 subjects performed 3 exercises: Modified Push-Up Plus (Wall Version), Modified Knee Push-Up Plus (Floor version) and Serratus Punch. Electromyographic (EMG) data was collected from the SA (surface) and PM (fine-wire EMG). RESULTS: During the Serratus Punch the SA activity was significantly higher than the PM activity. During the Modified Push-Up Plus exercises (both Wall and Floor version), the SA and PM activity were comparable. The PM showed the highest activity during the Serratus Punch and the Modified Push-Up Plus (Floor), which was significantly higher than during the Modified Push-Up Plus (Wall). The SA showed the highest activity during the Serratus Punch, which was significantly higher than during the Modified Push-Up Plus (Floor) which was in turn significantly higher than the activity during the Modified Push-Up Plus (Wall). CONCLUSIONS: All exercises activated the PM between 15 and 29% Maximum Voluntary Isometric Contraction and the SA between 15 and 43%. The Modified Push-Up Plus exercise against the wall and the floor activated the SA and PM to a similar degree. When maximum activation of the SA with minimal activation of the PM is desired in healthy subjects, the "Serratus punch" seems to be the optimal exercise.

Modifying the shoulder joint position during shrugging and retraction exercises alters the activation of the medial scapular muscles.

BACKGROUND: In patients with shoulder or neck pain, often an imbalance of the activation in the scapular upward and downward rotators is present which can cause abnormalities in coordinated scapular rotation. Shrug exercises are often recommended to activate muscles that produce upward rotation, but little information is available on the activity of the downward rotators during shrugging exercises. The position used for the shrug exercise may affect the relative participation of the medial scapular rotators. OBJECTIVES: To compare muscle activity, using both surface and fine-wire electrodes, of the medial scapular muscles during different shoulder joint positions while performing shrug and retraction exercises. DESIGN: Controlled laboratory study. METHOD: Twenty-six subjects performed 3 different exercises: shrug with the arms at the side while holding a weight ("Shrug"), shrug with arms overhead and retraction with arms overhead. EMG data with surface and fine wire electrodes was collected from the Upper Trapezius (UT), Levator Scapulae (LS), Middle Trapezius (MT), Rhomboid Major (RM) and Lower Trapezius (LT). RESULTS: The results showed that activity levels of the main medial scapular muscles depend upon the specific shoulder joint position when performing shrug and retraction exercises. High UT activity was found across all exercises, with no significant differences in UT activity between the exercises. The LS and RM activity was significantly lower during "ShrugOverhead" and the RM, MT and LT activity was significantly higher during "RetractionOverhead". CONCLUSIONS: This study has identified that all three exercises elicited similar UT activity. LS and RM activity is decreased with the "ShrugOverhead" exercise. The "RetractionOverhead" was the most effective exercise in activating the medial scapular muscles.

Evidence-based rehabilitation of athletes with glenohumeral instability.

PURPOSE: To give an overview of current knowledge and guidelines with respect to evidence-based rehabilitation of athletes with glenohumeral instability. METHODS: This narrative review combines scientific evidence with clinical guidelines based on the current literature to highlight the different components of the rehabilitation of glenohumeral instability. RESULTS: Depending on the specific characteristics of the instability pattern, the severity, recurrence, and direction, the therapeutic approach may be adapted to the needs and demands of the athlete. In general, attention should go to (1) restoration of rotator cuff strength and inter-muscular balance, focusing on the eccentric capacity of the external rotators, (2) normalization of rotational range of motion with special attention to the internal rotation ROM, (3) optimization of the flexibility and muscle performance of the scapular muscles, and (4) gradually increasing the functional sport-specific load on the shoulder girdle. The functional kinetic chain should be implemented throughout all stages of the rehabilitation program. Return to play should be based on subjective assessment as well as objective measurements of ROM, strength, and function. CONCLUSIONS: This paper summarizes evidence-based guidelines for treatment of glenohumeral instability. These guidelines may assist the clinician in the prevention and rehabilitation of the overhead athlete. LEVEL OF EVIDENCE: Expert opinion, Level V.

Optimal Normalization Tests for Muscle Activation of the Levator Scapulae, Pectoralis Minor, and Rhomboid Major: An Electromyography Study Using Maximum Voluntary Isometric Contractions.

OBJECTIVE: To identify maximum voluntary isometric contraction (MVIC) test positions for the deeper-lying scapulothoracic muscles (ie, levator scapulae, pectoralis minor, rhomboid major), and to provide a standard set of a limited number of test positions that generate an MVIC in all scapulothoracic muscles. DESIGN: Cross-sectional study. SETTING: Physical and rehabilitation medicine department. PARTICIPANTS: Healthy subjects (N=21). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Mean peak electromyographic activity from levator scapulae, pectoralis minor, and rhomboid major (investigated with fine-wire electromyography) and from upper trapezius, middle trapezius, lower trapezius, and serratus anterior (investigated with surface electromyography) during the performance of 12 different MVICs. RESULTS: The results indicated that various test positions generated similar high mean electromyographic activity and that no single test generated maximum activity for a specific muscle in all subjects. The results of this study support using a series of test positions for normalization procedures rather than a single exercise to increase the likelihood of recruiting the highest activity in the scapulothoracic muscles. CONCLUSIONS: A standard set of 5 test positions was identified as being sufficient for generating an MVIC of all scapulothoracic muscles: seated T, seated U 135°, prone T-thumbs up, prone V-thumbs up, and supine V-thumbs up. A standard set of test positions for normalization of scapulothoracic electromyographic data that also incorporates the levator scapulae, pectoralis minor, and rhomboid major muscles is 1 step toward a more comprehensive understanding of normal and abnormal muscle function of these muscles and will help to standardize the presentation of scapulothoracic electromyographic muscle activity.

Evidence for the Use of Ischemic Compression and Dry Needling in the Management of Trigger Points of the Upper Trapezius in Patients with Neck Pain: A Systematic Review.

The aim of this review was to describe the effects of ischemic compression and dry needling on trigger points in the upper trapezius muscle in patients with neck pain and compare these two interventions with other therapeutic interventions aiming to inactivate trigger points. Both PubMed and Web of Science were searched for randomized controlled trials using different key word combinations related to myofascial neck pain and therapeutic interventions. Four main outcome parameters were evaluated on short and medium term: pain, range of motion, functionality, and quality-of-life, including depression. Fifteen randomized controlled trials were included in this systematic review. There is moderate evidence for ischemic compression and strong evidence for dry needling to have a positive effect on pain intensity. This pain decrease is greater compared with active range of motion exercises (ischemic compression) and no or placebo intervention (ischemic compression and dry needling) but similar to other therapeutic approaches. There is moderate evidence that both ischemic compression and dry needling increase side-bending range of motion, with similar effects compared with lidocaine injection. There is weak evidence regarding its effects on functionality and quality-of-life. On the basis of this systematic review, ischemic compression and dry needling can both be recommended in the treatment of neck pain patients with trigger points in the upper trapezius muscle. Additional research with high-quality study designs are needed to develop more conclusive evidence.

Analysis of scapular muscle EMG activity in patients with idiopathic neck pain: a systematic review.

It is proposed that altered scapular muscle function can contribute to abnormal loading of the cervical spine. However, it is not clear if patients with idiopathic neck pain show altered activity of the scapular muscles. The aim of this paper was to systematically review the literature regarding the differences or similarities in scapular muscle activity, measured by electromyography ( = EMG), between patients with chronic idiopathic neck pain compared to pain-free controls. Case-control (neck pain/healthy) studies investigating scapular muscle EMG activity (amplitude, timing and fatigue parameters) were searched in Pubmed and Web of Science. 25 articles were included in the systematic review. During rest and activities below shoulder height, no clear differences in mean Upper Trapezius ( = UT) EMG activity exist between patients with idiopathic neck pain and a healthy control group. During overhead activities, no conclusion for scapular EMG amplitude can be drawn as a large variation of results were reported. Adaptation strategies during overhead tasks are not the same between studies. Only one study investigated timing of the scapular muscles and found a delayed onset and shorter duration of the SA during elevation in patients with idiopathic neck pain. For scapular muscle fatigue, no definite conclusions can be made as a wide variation and conflicting results are reported. Further high quality EMG research on scapular muscles (broader than the UT) is necessary to understand/draw conclusions on how scapular muscles react in the presence of idiopathic neck pain.