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

Preparation For Flight: The Physical Profile of Pre-Professional and Professional Circus Artists in the United States

Background

Established norms for fitness and performance measures are lacking in circus arts. These would assist healthcare professionals and coaches to screen for readiness to participate in training or performance, determine post-injury return to performance, and develop targeted conditioning programs.

Purpose

The purpose of this research was to establish norms for trunk and extremity physical exam and performance measures in circus artists by professional status, assigned sex at birth (ASAB), and age.

Study Design

Descriptive laboratory study.

Methods

Circus artists (n=201; ages 13-69y; 172 females ASAB, 29 males ASAB) from 10 cities across the United States underwent a baseline physical examination including shoulder, hip and trunk measures of passive (PROM) and active (AROM) range of motion, measures of flexibility (shoulder and hip), strength (manual muscle tests, grip strength), cardiovascular fitness (3 minute-step test), balance (single limb and handstand), and performance, (pull-ups, and the closed kinetic chain upper extremity stability test [CKCUEST]). ANOVAs were used to determine between group differences by age and T-tests to discern differences by ASAB or professional status.

Results

Differences existed by professional status for shoulder external rotation PROM, hip PROM, hip flexibility, shoulder and abdominal strength, and cardiovascular fitness. Sex differences were seen in active scapular upward rotation, hip and shoulder PROM and flexibility, hip and grip strength, and for functional performance measures (pull-ups, CKCUEST). Differences by age were limited to active scapular upward rotation, shoulder PROM, flexibility and strength, cardiovascular fitness, and balance. Overall, professionals outperformed pre-professionals for lower abdominal strength, pull-ups, handstand balance, cardiovascular fitness, hamstring, and straddle flexibility. Generally, males ASAB demonstrated greater shoulder flexibility and upper body functional strength while females ASAB had greater hip and lumbar flexibility and hip strength. No measures showed consistent declines with increasing age, though some showed differences between adolescents and adults.

Conclusion

These normative values for physical characteristics and functional performance in pre-professional and professional circus artists may be used to guide screening for readiness to participate in advanced training or performance, return to performance after injury, and the development of targeted strength and conditioning programs.

Level of Evidence

3.

Scapular movement training is not superior to standardized exercises in the treatment of individuals with chronic shoulder pain and scapular dyskinesis: randomized controlled trial

PURPOSE

To investigate whether scapular movement training (SMT) is superior to standardized exercises in improving scapular biomechanics, behavioral, and clinical aspects of individuals with shoulder pain.

METHODS AND METHODS

A total of 64 individuals with chronic shoulder pain were randomly assigned to receive 16 sessions of SMT or SE over 8 weeks. Outcome measures included three-dimensional scapular kinematics, muscle activity of scapulothoracic muscles, pain, disability, fear-avoidance, kinesiophobia, and self-perceived changes. Kinematics and muscle activity were assessed at baseline and after treatment, and self-reported measurements at baseline, 4, 8, and 12 weeks.

RESULTS

SMT significantly (p < 0.05) decreased scapular internal rotation during arm elevation and lowering at sagittal and scapular planes (mean difference [MD]: ranged from 2.8 to 4.1°), and at lower angles of arm elevation and lowering at the frontal plane (MD: 3.4° and 2.4°, respectively), increased upper trapezius (UT) activity (MD: 10.3%) and decreased middle trapezius (MT) (MD: 60.4%) and serratus anterior (MD: 9.9%) activity during arm lowering compared to SE. Both groups significantly improved pain, disability, fear-avoidance, kinesiophobia, and self-perceived changes over 4 weeks, which was sustained over the remaining 8 weeks.

CONCLUSIONS

SMT is not superior to standardized exercises in improving scapular biomechanics, behavioral, and clinical aspects of individuals with shoulder pain.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03528499Implications for rehabilitationScapular movement training (SMT) showed small and likely not clinically relevant changes in scapular kinematics and muscle activity compared to standardized exercises.SMT and standardized exercises presented similar improvements in pain, disability, fear-avoidance beliefs, kinesiophobia, and self-perceived change in health condition immediately following 4-weeks of treatment, which was sustained over the following 8 weeks.The changes in patient-reported outcome measures are unlikely to be associated with changes in scapular kinematics and electromyographic activity.Clinicians should consider other factors than scapular movement during the treatment of patients with shoulder pain.

Immediate Effects of the Reverse Plank Exercise on Muscle Thickness and Postural Angle in Individuals with the Forward Shoulder Posture

The forward shoulder posture (FSP) results from shoulders being pulled forward by shortened anterior shoulder girdle muscles. The objective of this study was to investigate the short-term effectiveness of the reverse plank exercise on parascapular muscle thickness and forward shoulder angle (FSA) in patients with FSP. Participants were divided into the FSP and non-FSP (NFSP) groups based on the observed angle between the horizontal line of the C7 spinous process and the acromion process. All participants performed a total of five sets of reverse plank exercises at 30 s per set. FSA and muscle thickness of the pectoralis major (PM), serratus anterior (SA), upper trapezius (UT), and lower trapezius (LT) were measured before and after the reverse plank exercise. The muscle thicknesses of the SA and LT, and the FSA, were significantly increased after exercise in the FSP group (p < 0.05). Muscle thickness of the PM and UT significantly decreased after the exercise. In the NFSP group, muscle thickness of the LT was significantly increased, and muscle thickness of the PM and UT were significantly reduced after exercise (p < 0.05). Upon using between-group analysis, there were significant differences between the FSA, SA, UT, and LT groups (p < 0.05). The reverse plank exercise has the short-term benefit of correcting and preventing FSP by increasing SA and LT thickness while decreasing PM and UT thickness. We believe that the reverse plank exercise significantly improved the ability to prevent FSP in FSP-related muscles and was beneficial in achieving optimal postural alignment.

Supine scapular punch: An exercise for early phases of shoulder rehabilitation?

BACKGROUND

Serratus anterior strengthening generally appears in shoulder rehabilitation protocols. This study's aim was to measure electromyographic activity of the serratus anterior, upper trapezius, and infraspinatus muscles during the Supine Scapular Punch exercise in healthy volunteers and those with unilateral shoulder pain.

METHODS

Fifty-four participants were included and grouped as without (n = 34, age = 25.8 years) or with unilateral shoulder pain (n = 20, age = 26.3 years, visual analogue scale = 4.15 cm). Electromyographic activity of the serratus anterior, upper trapezius, and infraspinatus muscles was assessed during Supine Scapular Punch (four phases: P1 = press up concentric, P2 = Supine Scapular Punch concentric, P3 = Supine Scapular Punch eccentric, P4 = press up eccentric) performed under two conditions, with and without additional load.

FINDINGS

Overall muscle activity during P1 and P4 was negligible (< 10% maximal voluntary isometric contractions). During P2 and P3, no statistically significant differences in serratus anterior and upper trapezius muscle activity were found between groups, with moderate to high serratus anterior activity (28.94% to 44.3%) and very low upper trapezius activity (< 6%). Upper trapezius/serratus anterior activity ratios ranged from 0.09 to 0.18. Overall infraspinatus muscle activity was always very low (< 10%).

INTERPRETATION

The Supine Scapular Punch induces moderate to high serratus anterior muscle activity with very low upper trapezius and infraspinatus activation. Based on these results, the Supine Scapular Punch is a safe exercise that can be used in the early phases of shoulder rehabilitation.

Shoulder muscle activation during scapular protraction exercise with arm rotation

BACKGROUND

The role of the serratus anterior is to maintain scapular stability. To strengthen this muscle, scapular protraction exercises are typically performed. Although the angle of arm rotation leads to changes in shoulder muscle activation, the arm rotation position is not normally determined.

OBJECTIVE

To investigate if scapular muscle activations were changed by combining arm external rotation during scapular protraction exercises.

METHODS

Thirty-four healthy men were enrolled in this study. Participants were instructed to perform scapular protraction exercises at 90∘ and 120∘ of shoulder flexion while in the standing and supine positions. Two different arm rotation angles were used: the thumb-up position (neutral position) and the maximum arm external rotation (ER) position. The percentages of maximum voluntary contractions (%MVCs) were measured, and %MVCs in the neutral and arm ER positions were compared.

RESULTS

Muscle activities of the middle serratus anterior (MSA) and lower serratus anterior (LSA) in the arm ER position were significantly higher than those in the neutral position during all tasks. The highest MSA and LSA positions were observed with the arm ER position of 120∘ while standing.

CONCLUSIONS

Scapular protraction exercises with arm ER resulted in a higher serratus anterior activity.

Comparison of Activity in Scapular Stabilizing Muscles during Knee Push-Up Plus and Modified Vojta's 3-Point Support Exercises

Selective serratus anterior (SA) strengthening without compensatory movement of the shoulder stabilizers is essential for shoulder stability and functional movement without causing shoulder injury and dysfunction. The purpose of this study was to compare electromyographic (EMG) activity between the SA, upper trapezius (UT), lower trapezius (LT), and pectoralis major (PM) during the knee push-up plus (KPUP) and modified Vojta’s 3-point support (MV3PS) exercises. Scapular stabilizer muscle activity (UT, LT, SA, and PM) was investigated during the KPUP and MV3PS exercises in 40 healthy adults (19 males, 21 females) using surface EMG. Muscle activity of the SA was significantly higher during the MV3PS exercise than during the KPUP (p < 0.05). However, muscle activity in the PM was significantly lower during the MV3PS exercise (p < 0.05). In addition, the LT and UT showed less muscle activity during the MV3PS exercise, although the difference was not statistically significant (p > 0.05). These findings suggest that the MV3PS exercise better activates the SA than KPUP.

Scapular stabilization exercise based on the type of scapular dyskinesis versus traditional rehabilitation training in the treatment of periarthritis of the shoulder: study protocol for a randomized controlled trial

Background

Periarthritis of the shoulder is a common disease leading to dysfunction of the shoulder joint and have a significant impact on patients’ daily life. Evidence shows that there is a close relationship between scapular dyskinesis (SD) and shoulder diseases. Scapular stabilization exercise has been proved to be efficacious in relieving pain and improving function. However, there is no targeted exercise based on the type of scapular dyskinesis. This study will investigate the potential of scapular stabilization exercise based on the type of scapular dyskinesis in treating periarthritis of the shoulder.

Methods

This study is a prospective, randomized controlled, parallel-group trial, intending to recruit 90 patients diagnosed with periarthritis of the shoulder. Patients will receive scapular stabilization exercise training based on the type of scapular dyskinesis or receive traditional rehabilitation training conducted for 30 min, once a day, for 6 weeks. The primary outcome is Constant-Murley score (CMS), and other outcomes include pain degree, range of motion (ROM), type of scapular dyskinesis, scapula position, and patients’ satisfaction with shoulder function. Assessments will be performed at baseline, 2-, 4- and 6-week treatment, and at the 6-week follow-up after the end of treatment.

Discussion

This study will be the first study to investigate the clinical efficacy of scapular stabilization exercise based on the type of scapular dyskinesis in patients with periarthritis of the shoulder. The results may provide evidence of the effect of targeted scapular stabilization exercise in improving shoulder function and correcting scapular dyskinesis, and provide valuable information for future research.

Trial registration

This study had been registered in the Chinese Clinical Trials Registry. Registration number: ChiCTR2100044332 at March 14, 2021.

A Thoracic Outlet Syndrome That Concealed a Glioblastoma. Findings from a Case Report

Background: Glioblastoma is the most frequent and aggressive malignant brain tumor among adults. Unfortunately, its symptoms can vary considerably depending on the size, location and the anatomic structures of the involved brain. Case report: A 58-year-old male amateur cyclist who suffered from sharp arm pain was examined for a thoracic outlet syndrome due to a previous clavicle fracture. Because of ambiguous results of the neck and nerve plexus imaging, he was referred to a neurosurgeon who properly suspected a brain tumor. The neuroimaging of the brain shown a 3 cm disploriferative mass with a blood enhancement within the left parietal lobe. The mass was urgently removed, and its histologic analysis stated a grade 4 glioblastoma. Conclusion: This case report highlights the differential diagnosis process and the teamwork approach needed to diagnose a rare presentation of a brain glioblastoma, which started its symptoms mimicking a thoracic outlet syndrome caused by a previous bone fracture.

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.

Optimal activation ratio of the scapular muscles in closed kinetic chain shoulder exercises: A systematic review

BACKGROUND

Muscle synergies contribute to scapular position during arm movement. The trapezius and serratus anterior (SA) muscles are the main stabilizers and are therefore the main target muscles of therapeutic exercises.

OBJECTIVE

To systematically review the current literature investigating the optimal activation ratio of the scapular muscles during a range of closed kinetic chain exercises.

METHODS

A systematic review search was conducted to identify studies reporting shoulder electromyography (EMG) activity during rehabilitation exercises in healthy participants. The search was conducted in PubMed, Cochrane Library, MEDLINE, CINAHL, Scopus, SPORTDiscus, and ScienceDirect. The included studies reported closed kinetic chain exercises and the muscle activity as a percentage of maximum voluntary isometric contraction (%MVIC) or muscle ratios of the lower trapezius (LT), middle trapezius (MT), and SA with respect to the upper trapezius (UT). Muscle ratios were classified as optimal if they were equal to or lower than 0.6, and the adapted Newcastle-Ottawa Scale (NOS) was used to evaluate the methodological quality of the selected studies.

RESULTS

Twenty-nine studies were included in this review; 7 main exercises and 30 variations of these were reported. The average electromyographic activity of the concentric and eccentric phase was considered. Half Push Up, Push Up Plus, and Scap Protraction exercises showed optimal SA activity (UT/SA < 0.6), while Press Up, Half Push Up, and One Hand Plank exercises showed optimal LT activity (UT/LT < 0.6). According to the NOS, 15 studies were classified as moderate methodological quality.

CONCLUSIONS

The exercises in higher positions (e.g. exercises with the trunk closest to the vertical line) or unstable surfaces tend to favor UT activity over the MT, LT and SA. The exercises including scapular retraction showed optimal UT/MT and UT/LT ratios, while those including scapular protraction showed optimal UT/SA ratios. This will assist therapists in the correct selection of exercises for shoulder rehabilitation.

The Addition of Real-time Ultrasound Visual Feedback to Manual Facilitation Increases Serratus Anterior Activation in Adults With Painful Shoulders: A Randomized Crossover Trial

OBJECTIVE

Serratus anterior (SA) muscle activation may be decreased with subacromial pain syndrome. The purpose of this study was to determine whether the addition of real-time ultrasound (RTUS) visual feedback increased activation of SA in adults with painful shoulders in comparison to manual facilitation alone.

METHODS

This assessor-blinded, 2-period, randomized cross-over trial was conducted in a university medical imaging laboratory. Adults with mild-moderate unilateral subacromial pain received both interventions in random order with at least 1-week washout between interventions. Fourteen participants were randomized to receive manual facilitation with RTUS first, and 13 were randomized to receive manual facilitation alone first. Fifteen repetitions of a supine ``serratus punch'' were facilitated by RTUS visual feedback with manual facilitation or by manual facilitation alone. Levels of SA activation via surface electromyography were normalized to a maximum voluntary isometric contraction.

RESULTS

A total of 25 participants completed the full trial of both interventions. Data from 25 participant periods for RTUS with manual facilitation and data from 26 participant periods for manual facilitation only were analyzed. The predicted marginal mean difference between interventions was 55.5% (95% CI = 13.9% to 97.1%) in favor of the addition of RTUS feedback. No adverse effects occurred.

CONCLUSION

RTUS visual feedback increases SA activation in adults with painful shoulders compared with manual facilitation alone.

IMPACT

Determining if RTUS can improve SA muscle activation may help clinicians improve physical therapist interventions for subacromial pain syndrome.

Scapular movement training versus standardized exercises for individuals with chronic shoulder pain: protocol for a randomized controlled trial

BACKGROUND

Scapular focused exercise interventions are frequently used to treat individuals with shoulder pain. However, evidence for changes in scapular motion after intervention is limited.

OBJECTIVE

To compare the effects of scapular movement training versus standardized exercises for individuals with shoulder pain.

METHODS

This will be a single-blinded randomized controlled trial. Sixty-four individuals with shoulder pain for at least 3 months, scapular dyskinesis, and a positive scapular assistance test will be randomly allocated to one of two groups: Scapular Movement Training (group 1) and Standardized Exercises (group 2). Group 1 will receive education about scapular position and movement, and be trained to modify the scapular movement pattern. Group 2 will perform stretching and strengthening exercises. Both groups will be treated twice a week for eight weeks. Three-dimensional scapular kinematics and muscle activity of the serratus anterior and upper, middle, and lower trapezius during elevation and lowering of the arm will be assessed at baseline and after 8 weeks of treatment. Pain intensity, function, fear avoidance beliefs, and kinesiophobia will be assessed at baseline and after 4 and 8 weeks of treatment, and 4 weeks after the end of treatment.

CONCLUSIONS

The results of this study may contribute to a better understanding of the efficacy of scapular focused treatments for individuals with shoulder pain.

CLINICAL TRIAL REGISTRATION

NCT03528499.

Differences in scapular motion and parascapular muscle activities among patients with symptomatic and asymptomatic rotator cuff tears, and healthy individuals

Background

Altered scapular motion is thought to be one of the factors associated with the development of symptomatic rotator cuff tears. However, the differences in kinematics and muscle activities of scapular upward/downward rotation between patients with symptomatic and asymptomatic tears are unclear. The purpose of this study was to compare the differences in kinematics and muscle activities of scapular rotation among patients with symptomatic and asymptomatic tears, and healthy individuals.

Methods

Twenty-three patients with rotator cuff tears and 9 healthy individuals (healthy group) participated in this study. Based on a visual analog scale (VAS, 0-100 mm), the patients were divided into symptomatic (13 patients; VAS ≥20 mm) and asymptomatic (10 patients; VAS <20 mm) groups. Scapular upward rotation was measured with a digital inclinometer. Elasticities of the upper trapezius, levator scapulae, and rhomboid major were assessed by using ultrasound real-time tissue elastography to quantify their muscle activities. All measurements were performed at 0°, 60°, 90°, and 120° of active arm elevation in the scapular plane.

Results

Scapular upward rotation was significantly less in the symptomatic group (9.4° ± 5.6°) compared with the asymptomatic group (15.7° ± 6.0°; P = .022) at 90° of arm elevation. The activity of the levator scapulae was significantly higher in the symptomatic group compared with the asymptomatic and healthy groups (P = .013 and P = .005, respectively) at 90° of arm elevation. The activity of the upper trapezius was significantly higher in the symptomatic group compared with the healthy group (P = .015) at 120° of arm elevation.

Conclusion

Patients with symptomatic rotator cuff tears showed less scapular upward rotation and higher activity of the levator scapulae at 90° of arm elevation compared to patients with asymptomatic rotator cuff tears.

Electromyographic Analysis of Shoulder Neuromuscular Activity in Women Following Breast Cancer Treatment: A Cross-Sectional Descriptive Study

Certain secondary effects derived from medical treatment in breast cancer can favor the development of alterations in shoulder biomechanics. To the best of our knowledge, persistent peripheral pain as a key factor for the development of neuromuscular activity impairments has not been analyzed. A cross-sectional descriptive study was carried out. A total of 90 women were included and allocated to three groups: (i) 30 women with persistent peripheral pain after breast cancer treatment, (ii) 30 women without pain after breast cancer treatment, and (iii) 30 healthy women. Surface electromyography was employed to measure the onset and amplitude of the muscle activity of three shoulder movements. Statistically significant differences were found in the neuromuscular activity for all the muscles and shoulder movements among women with persistent pain versus healthy women (i.e., amplitude muscle activity variable p < 0.001). Statistically significant differences were also observed in the neuromuscular activity for certain muscles in shoulder movements among women with persistent pain versus women without pain, as well as between women without pain versus healthy women. Therefore, following breast cancer treatment, women showed alterations in their shoulder neuromuscular activity, which were more significant if persistent pain existed. These findings may contribute to developing a selective therapeutic exercise program that optimizes the shoulder neuromuscular activity in women after breast cancer treatment.

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.

Serratus Anterior and Upper Trapezius Electromyographic Analysis of the Push-Up Plus Exercise: A Systematic Review and Meta-Analysis

CONTEXT

Whereas the serratus anterior (SA) and the upper trapezius (UT) work as a force couple for scapular motion, weakness of the SA and overactivation of the UT are often present in overhead athletes with shoulder dysfunction. Therefore, researchers addressing an intramuscular imbalance between the SA and UT have focused on finding exercises that target the weak SA and minimally activate the UT.

OBJECTIVE

To compare the effectiveness of push-up plus (PUP) exercise variants based on the electromyographic (EMG) activity of the SA and UT.

DATA SOURCES

A systematic search of PubMed and Scopus between January 1, 2000, and March 31, 2008.

STUDY SELECTION

Studies of PUP exercises that involved EMG analysis.

DATA EXTRACTION

We assessed study quality using the Critical Appraisal Skills Program. For the systematic analysis, the following data were extracted: (1) author, year, and study design; (2) participant characteristics; (3) type of PUP intervention; (4) EMG outcome measures; and (5) main results. For the meta-analysis, the EMG data of the SA and UT were calculated using the mean difference of EMG activity with a 95% confidence interval.

DATA SYNTHESIS

Based on 19 studies with 356 participants, different hand positions (the distance between the hands, shoulder-flexion angle, and elbow-flexion angle) and different lower extremity positions variably affected the activation of the SA and UT during the PUP exercise. Also, when participants performed the PUP on an unstable surface compared with a stable surface, UT activity increased 2.74% (95% confidence interval = 0.07%, 5.41%).

CONCLUSIONS

The standard PUP exercise elicited high EMG activity of the SA. Participants generated higher SA and lower UT EMG activity when they performed the PUP exercise on a stable surface in full elbow extension, with the hands placed shoulder-width apart, shoulder-flexion angles of 110° or 120°, and the ipsilateral lower extremity lifted.

Comparison of Shoulder Protraction Strength and Electromyography Activity of Serratus Anterior and Pectoralis Major in Subjects With or Without a Winged Scapula

CONTEXT

A winged scapula (WS) is associated with faulty posture caused by weakness of the serratus anterior (SA), which mainly acts as a scapular stabilizer muscle. It is important to accurately assess and train the SA muscle with a focus on scapula stabilizers during musculoskeletal rehabilitation of individuals with a WS.

OBJECTIVE

The authors examined muscle activity in the SA and pectoralis major (PM), upper trapezius (UT), and anterior deltoid (AD) as well as shoulder protraction strength during isometric shoulder protraction in individuals with and without a WS.

DESIGN

Cross-sectional study.

SETTING

A clinical biomechanics laboratory.

PARTICIPANTS

In total, 27 males with no shoulder, neck, or upper-extremity pain participated.

MAIN OUTCOME MEASURES

Isometric shoulder protraction strength was collected and surface electromyography used to measure the activity of the SA, PM, UT, and AD muscles and selective SA activity ratio to other shoulder muscles.

RESULTS

Electromyography activity of the SA muscle and shoulder protraction strength were significantly lower in individuals with a WS compared with the non-WS group (P < .05). In contrast, PM muscle activity and the PM-to-SA, UT-to-SA, and AD-to-SA ratios were significantly greater in individuals with a WS than in individuals without winging (P < .05).

CONCLUSIONS

Isometric shoulder protraction for measuring SA strength in individuals with a WS should focus on isolated muscle activity of the SA, and SA strengthening exercises are important for individuals with a WS.

Kinesiologic considerations for targeting activation of scapulothoracic muscles - part 1: serratus anterior

BACKGROUND

The serratus anterior (SA) is capable of a wide range of actions across the scapulothoracic joint. Furthermore, the lack of control, strength, or activation of this important muscle is believed to be associated with several painful conditions involving the shoulder complex. Studies and clinical intuition have therefore identified several exercises that selectively target the activation of the SA.

METHODS

This paper reviews the anatomy, innervation, testing, and complex actions of the SA. In addition, this paper describes the classic signs and symptoms of weakness or reduced activation of the SA. Several exercises are described and illustrated that purportedly target the activation of the SA, with the intention of optimizing muscular control and encouraging pain free shoulder motion.

CONCLUSIONS

This review provides the theoretical background and literature-based evidence that can help explain the SA's complex pathokinesiology, as well as guide the clinician to further develop exercises that likely challenge the muscle. This paper is written along with a companion paper entitled: Kinesiologic considerations for targeting activation of scapulothoracic muscles: part 2: trapezius. Both papers prepare the reader to expand their pallet of exercises that target and challenge these two dominant muscles, with a goal of improving function of the shoulder for several painful conditions caused by their reduced or altered activation pattern.

Electromyographic activity of the serratus anterior and pectoralis major during isometric scapular protraction at different resistance intensities in subjects with and without a winged scapula

BACKGROUND

During maximal isometric protraction, it is important to determine the optimal resistance intensity in subjects with a winged scapula, for inducing isolated activity of the serratus anterior against the pectoralis major, which is activated as a synergistic muscle. The aim of the present study was to determine electromyographic activities of the serratus anterior and pectoralis major muscles during isometric shoulder protraction at different levels in subjects with and without a winged scapula.

METHODS

Thirty male subjects performed isometric shoulder protraction in a sitting position at different resistance intensity levels (100%, 80%, and 60% of maximal protraction strength). Surface electromyographic data of the serratus anterior and pectoralis major muscles were gathered simultaneously using fixed instrumentation to measure isometric shoulder protraction.

FINDINGS

Muscle activity of the serratus anterior in subjects without a winged scapula was significantly greater than that of subjects with a winged scapula across all three conditions, whereas muscle activity of the pectoralis major was lower in subjects without a winged scapula. In addition, winged scapula muscle activity corresponding to maximal protraction was significantly greater than that in the submaximal condition.

INTERPRETATION

In a clinical setting, submaximal resistance can be more optimal than maximal effort during isometric shoulder protraction in individuals with a winged scapula.

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.

Effects of horizontal shoulder abduction and adduction on the activity and strength of the scapular protractors

Increased activity of the serratus anterior (SA) muscle combined with decreased activity of the pectoralis major (PM) muscle during scapular protraction exercise is a widely used method for selective strengthening of the former muscle. However, the role played by the PM during maximal scapular protraction remains unclear. The objective of our study was to investigate the effects of horizontal shoulder abduction (decreasing PM activity) and adduction (increasing activity) on the strength and activity of the scapular protractors (the SA and PM) during maximal protraction. Twenty-nine healthy males performed maximal scapular protraction combined with horizontal shoulder abduction or adduction. The strength and activity of the PM and SA decreased significantly (both p < 0.01) during maximal scapular protraction combined with horizontal shoulder abduction, compared with maximal scapular protraction alone, but increased significantly (both p < 0.01) when maximal scapular protraction was combined with horizontal shoulder adduction. We thus conclude that the PM stabilizes the activated SA during maximal scapular protraction, which effectively increases SA activity and scapular protraction strength in the serratus punch posture.