Incorporation of the Kinetic Chain Into Shoulder-Elevation Exercises: Does It Affect Scapular Muscle Activity?

Investigation of muscle activation during kinetic chain based exercises in individuals with and without forward head posture

BACKGROUND

The Band Pull-Apart (BPA) exercise is used to strengthen the periscapular muscles. It was recently stated that the lower extremity and trunk movements should be included in the shoulder rehabilitation programs to optimize an effective energy transfer throughout the kinetic chain.

OBJECTIVE

The aim of this study is to investigate the effects of kinetic chain based BPA exercise on the muscle activations of the sternocleidomasteideous (SCM) and the trapezius muscles in individuals with and without forward head posture (FHP).

METHODS

Eighteen individuals with FHP and 18 individuals without FHP were included. Photographic measurements were made to identify individuals with FHP. The muscle activations of SCM, Upper Trapezius (UT), Middle Trapezius (MT), and Lower Trapezius (LT) were measured with surface EMG. BPA exercise was performed in the standing, unipedal standing, squat, unipedal squat, and Bulgarian split squat (BSS).

RESULTS

There was no Group × Exercise interaction for the SCM, UT, MT, LT muscle activations, or for the UT/MT and UT/LT ratios (p> 0.05). While there was a difference in the activation of all muscles between individuals with and without FHP (p< 0.05), both ratios were similar (p> 0.05). There was a statistically significant difference between exercises for SCM, MT, and LT muscle activations (p< 0.000 for these muscles), UT/MT (p< 0.000) and UT/LT ratios (p= 0.004). SCM muscle activation in squat was lower than activation in standing (Mean Difference (MD) = 2.5% Maximal Voluntary Isometric Contractions (MVIC); p= 0.004) and in unipedal standing (MD = 2.1% MVIC; p= 0.002). MT muscle activation in squat was higher than activation in standing (MD = 9.7% MVIC), unipedal standing (MD = 7.8% MVIC), unipedal squat (MD = 6.9% MVIC) and BSS (MD = 9.4% MVIC; p< 0.000 for these positions). LT muscle activation in the squat was higher than activation in the standing (MD = 8.5% MVIC) and unipedal squat (MD = 8.1% MVIC; p< 0.004 for these positions). UT/MT ratio in the squat was lower than standing (MD = 0.3), unipedal standing (MD = 0.2) and BSS (MD = 0.3; p< 0.000 for these positions). UT/LT ratio in squat was lower than unipedal squat (MD = 0.5) and BSS (MD = 0.6; p= 0.002; for these positions).

CONCLUSION

Performing the BPA exercise in the squat position is suggested in cases where lower SCM and UT muscle activation, lower UT/MT, and UT/LT ratios and higher MT and LT muscle activations are needed for individuals with and without FHP.

Muscle Activations of the Upper Extremity and Core during Elevation and Rotational Movements in Overhead Throwing Athletes

Background

A strong body of literature has been published outlining muscle activity differences during sports performance in groups of overhead athletes. However, there are limited studies that have directly compared the muscle activity in overhead athletes with and without history of shoulder injury during functional everyday tasks.

Purpose

This study aimed to identify muscle activities across fourteen upper extremity and core muscles during three functional everyday movements in athletes with and without history of shoulder injury.

Study Design

Cross-Sectional Study.

Methods

Thirty-two male overhead throwing athletes (fifteen healthy and seventeen injured) were recruited and completed three everyday functional movements of high elevation, low elevation, and rotation, using their dominant arm to move an object between two fixed positions. Electromyography (EMG) was recorded for fourteen muscles including: biceps brachii, deltoids (anterior, medial, and posterior), trapezius (upper and lower), pectoralis major, latissimus dorsi, serratus anterior, infraspinatus, external obliques, and gluteus maximus (all surface electrodes) and supraspinatus (fine wire electrode). Mixed model repeated measures ANOVA and post-hoc analysis assessed mean muscle activity (%MVC) between groups and each movement phase.

Results

Upper trapezius elicited higher mean activity in healthy athletes during both phases of the arm rotation task (p \< 0.05). No differences between groups were evident for arm elevation tasks. Qualitative analysis of muscle patterns during functional tasks reflected a temporal shift in muscle activation timings and magnitudes between athlete groups, suggesting potential compensatory mechanisms in injured athletes.

Conclusion

Injured overhead athletes appear to utilize other upper limb and shoulder girdle muscles to compensate for lower upper trapezius activity during functional everyday tasks.

Level of Evidence

3.

Supine counterstrain technique for rhomboid tender point

Because poor posture is a common instigating factor in back, shoulder, and neck pain, the rhomboid muscles should be considered in a complete physical evaluation. Previous techniques for treating a rhomboid tender point have addressed only one of the two main actions of the muscle, specifically retraction of the scapula utilizing shoulder abduction. This modified supine counterstrain technique for the rhomboid tender point incorporates both scapular retraction as well as superior, medial rotation of the inferior border of the scapula without abduction, providing a comprehensive treatment to accommodate patients with shoulder movement restrictions. This article discusses indications, contraindications, treatment, and a list of problem-solving strategies for the rhomboid tender point.

The influence of shoulder position during multi-joint exercises in the relative scapular muscles activity in symptomatic and asymptomatic conditions

BACKGROUND

Scapular muscles changes, as increased upper trapezius activity and decreased middle and lower trapezius and serratus anterior muscle activity, have been demonstrated in shoulder pain specific or non-specific conditions. Shoulder external rotation exercises have been recommended to improve scapular activity in shoulder pain.

OBJECTIVE

To evaluate the relative scapular muscles activity during multi-joint exercises combining shoulder external rotation, trunk rotation and scapular squeeze.

METHODS

Forty-one participants with and without shoulder pain were assessed in a cross-sectional study. They performed isometric multi-joint exercises at 0∘ and 90∘ of shoulder abduction with and without support. The relative activity of upper, middle, and lower trapezius and serratus anterior (upper/middle and lower portions) was measured through electromyography. The scapular muscular balance was assessed by the ratio between relative activity of the upper trapezius and the other muscles.

Role of active joint position sense on the upper extremity functional performance tests in college volleyball players

Background

It has been well established that proprioception plays a decisive role in shoulder stability and sport performance. Notwithstanding, there is a lack of clear association between active joint position sense (AJPS) and the performance of upper-extremity functional performance tests. The aim of this study was to determine whether the AJPS of the shoulder complex is associated with the performance of college volleyball players with the following functional tests: Y-Balance Test-Upper Quarter (YBT-UQ), Closed Kinetic Chain Upper-Extremity Stability Test (CKCUEST), and Seated Medicine Ball Throw (SMBT). The secondary aim was to investigate whether the magnitude of the proprioception error through the AJPS had the ability to act as a predictor for functional test scores.

Methods

Cross-sectional study with a convenience sampling. Healthy college volleyball players (≥12 h of training/week), 30 males and 22 females, between 18 and 26 years of age were included. AJPS of the shoulder (90° of flexion (90°Flex), 90° of internal rotation at 90° of abduction (90°IR/ABD), 90° of external rotation at 90° of abduction (90°ER/ABD)) and three upper-extremity functional performance tests (YBT-UQ, CKCUEST and SMBT) were assessed. A Pearson's test and a stepwise multiple linear regression analysis were used to determine possible associations and relationships between outcome measures, respectively.

Results

The analysis revealed that AJPS at 90°IR/ABD and 90°ER/ABD were the only proprioceptive variables with an association to the YBT-UQ and SMBT. Despite these relationships, only the AJPS at 90°IR/ABD was associated with the performance of the YBT-UQ in; superolateral direction (β = -0.7; 95% CI [-1.3 to 0.1]; p = 0.025); inferolateral direction (β = -1.5; 95% CI [-2.1 to -0.8]; p = 0.001); and composite score (β = -0.8; 95% CI [-1.3 to -0.3]; p = 0.002). From these, AJPS at 90°IR/ABD mainly explained the variability of YBT-UQ (inferolateral direction) performance (R² = 0.32; %R² = 0.32). Our findings allow for a possible expanded role for proprioception as a contributing factor in upper limb motor control during functional movements. Further research is required to explore and distinguish the associations between proprioception, motor control and sport performance involving the upper limbs.

Upper extremity field tests and isokinetic shoulder internal and external strength and power in sports active males

BACKGROUND: In order to guide sports active subjects with musculoskeletal (MSK) shoulder dysfunctions itis essential to have precise insights of possible weak links in the kinetic chain of their shoulder girdle with access to reference data. Equally, it is uncertain whether so-called functional shoulder strength tests are complementary to an isokinetic shoulder strength test. OBJECTIVE: To establish reference values and to clarify the relationship between two upper extremity field tests – the Scapular Muscle Endurance test (SME) and the Closed Kinetic Chain Upper Extremity Test (CKCUEST) and the isokinetic strength test of the shoulder internal (IR) and external rotators (ER). METHODS: Seventy-six male sport active men performed the CKCUEST, the SME, and underwent a bilateral isokinetic strength test to establish reference values of the isokinetic shoulder relative to body mass Peak Moment (PM/kg) and Power (Power/kg) for the IR and ER. A mixed-design ANOVA calculated possible side-to-side differences and one-way ANOVA was applied for eventually age group differences. Additionally, the relationship between the three tests was examined with a Spearman rank-order correlation coefficient. RESULTS: No significant correlations were indicated between the SME and the criterion isokinetic test and between the SME and CKCUEST. CONCLUSIONS: The main outcome parameters in this study warrant individual assessment as they measure different constructs, leading to a diverse profile of the shoulder.

Relationship of scapular dyskinesis with the pattern of activation of periescapular muscles during exercise

abstract The aim of the present study was to analyze the activation pattern of the serratus anterior (SA), upper trapezius (UT), and lower trapezius (LT) muscles during periscapular exercises in individuals with and without ED, and to identify which proposed exercise presents greater activation of the periscapular muscles. Fourteen women, aged between 18 and 30 years, participated in this study, divided into a control group (n = 8) and a dyskinesis group (n = 8). The determination of the presence of ED was performed according to the analysis of scapular movement during arm elevation, using the yes/no classification. To evaluate muscle activation, electromyography signals of the SA, UT, and LT muscles were collected during exercise. The exercise protocol was composed of three repetitions of the exercises: punch up, wall slide, and scaption. The results showed that the ED group showed less activation of the AS and TT than the control group. During the scaption and wall slide exercises, the DE group showed less activation of the AS in relation to those without DE. There was no difference in muscle activation between the exercises. That individuals with dyskinesis have less activation of the muscles that control scapular mechanics and that the type of exercise did not influence the activation of the periscapular muscles.

Team Approach: Treatment of Shoulder Instability in Athletes

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Shoulder instability is a complex problem with a high rate of recurrence in athletes. Treatment of a first-time subluxation or dislocation event is controversial and depends on patient-specific factors as well as the identified pathology.

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Athletic trainers and physical therapists are an integral part of the treatment team of an in-season athlete who has experienced a shoulder instability event. Through comprehensive physiological assessments, these providers can effectively suggest modifications to the patient's training regimen as well as an appropriate rehabilitation program.

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Surgical intervention for shoulder stabilization should use an individualized approach for technique and timing.

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A team-based approach is necessary to optimize the care of this high-demand, high-risk population.