Muscle recruitment during plyometric exercises in overhead athletes with and without shoulder pain

Electromyographic activity of shoulder muscles on two preventive exercise programmes for swimmer's shoulder: elastic band versus weight

Strength programmes have shown good results in preventing swimmer's shoulder. However, there aren't studies based on electromyographic (EMG) analysis in these programmes. This study aims to compare an EMG activity of the middle trapezius (MT), lower trapezius (LT), infraspinatus (IS), serratus anterior (SA), and pectoralis major (PM) in two swimmer's shoulder preventive programmes - one performed with elastic band and the other with weights. Twenty competitive swimmers performed two strength programmes consisting of five exercises each, while the analysis of EMG activity in MT, LT, IS, SA, and PM for each exercise was recorded. The superficial EMG was used to collect data at a sampling frequency of 1000 hz. The Paired Sample T-test or the Wilcoxon test was applied to compare EMG activity between programmes. The internal rotation at 90º (p < 0.001) and external rotation at 90º (p ≤ 0.01) exercises produced high myoelectric shoulder muscle activity with an elastic band. Conversely, scapular punches (p < 0.001) exercise has high shoulder EMG activity when performed with weights. Performing the same preventive exercise programme with two different instruments produces great variability in the myoelectric activity of the shoulder muscles.

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.

Risk of injury and kinematic assessment of the shoulder biomechanics during strokes in padel players: a cross-sectional study

BACKGROUND

Padel players commonly suffer from shoulder pain and the particularly high incidence is probably linked to the high frequency of strokes. In addition, due to the repetitive technical gesture, an adequate technique is essential in terms of performance and injury risk prevention. Aim of this study was to objectively evaluate shoulder kinematic during the athletic gesture to analyze the risk factors linked to padel strokes.

METHODS

Professional and amateur padel players underwent a three-dimensional motion analysis of the padel strokes utilizing optoelectronic and surface electromyography systems (BTS Bioengineering, Garbagnate Milanese, Milan, Italy).

RESULTS

Twelve padel players were included in this study (10 professional players in Group A and 10 amateurs in Group B). Experience influences the execution of padel strokes with a significant difference between group A and B in terms of gleno-humeral rotation and scapular tilt. Moreover, a subgroup analysis revealed that male players execute voleè with a higher external rotation (P=0.043), and forehand with a higher scapular tilt (P=0.044).

CONCLUSIONS

The results confirm that the high ranges of motion of the overhead strokes could rise the risk of slap lesion, impingement, and glenohumeral internal rotation deficit. However, a correct execution of the athletic gesture is linked with a dynamic stabilization of the humeral head. In conclusion, the kinematic analysis could help in the early identification of the kinematic alteration to build a tailored rehabilitation plan based on the athlete's needs.

Scapular kinematics and muscle activity during Yi Jin Bang exercises

Introduction: Scapular dyskinesis is commonly associated with subacromial pain syndrome (SAPS). Addressing scapular dyskinesis is widely accepted as an important component of shoulder rehabilitation. Our previous randomized controlled trial showed that Yi Jin Bang (YJB) exercises could effectively manage SAPS, but scapular motions and muscle activity during YJB exercises remain unknown. This study examined scapular kinematics synchronously with scapular muscle activation during YJB exercises. Methods: Thirty healthy participants with no shoulder complaints were enrolled in this study. Three-dimensional (3D) scapular kinematics and electromyography (EMG) activation of the upper trapezius, middle trapezius, lower trapezius, serratus anterior, anterior deltoid, middle deltoid, and posterior deltoid were synchronously measured during nine YJB movements. Results: During all YJB movements, the scapula was upwardly rotated and anteriorly tilted, with more upward rotation and a similar or less anterior tilt than the mean resting scapular angle. Column rotation, arm crossover, shoulder support circle, and armpit support high lift generated more internal rotation than the mean resting scapular angle, with the angles of internal rotation significantly greater than the other five movements (p < 0.001). Regarding EMG activity, all YJB movements elicited low activity (1.42%-19.19% maximal voluntary isometric contraction [MVIC]) from the upper trapezius and posterior deltoid and low to moderate activity (0.52%-29.50% MVIC) from the middle trapezius, lower trapezius, serratus anterior, anterior deltoid, and middle deltoid. Conclusion: YJB exercises could be useful in the middle to later phases of shoulder rehabilitation. For patients with insufficient external rotation, some YJB movements should be prescribed with caution.

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.

Could the Improvement of Supraspinatus Muscle Activity Speed up Shoulder Pain Rehabilitation Outcomes in Wheelchair Basketball Players?

Shoulder pain (SP) is a common clinical complaint among wheelchair basketball (WB) players, since their shoulders are exposed to intense overload and overhead movements. The supraspinatus tendon is the most exposed to WB-related injuries and it is primarily responsible for SP in WB athletes. In these cases, SP rehabilitation remains the main treatment, but there is still a lack of specific protocols which should be customized to WB players' peculiarities and to the supraspinatus muscle activity monitor, and the improvement of rehabilitation outcomes is slow. Thus, the aim of this study was to verify if the improvement of supraspinatus muscle activity, monitored in real time with surface electromyography (sEMG) during the execution of therapeutic exercises, could speed up SP rehabilitation outcomes in WB players. Thirty-three athletes were enrolled. They were divided into two groups. Both groups underwent the same shoulder rehabilitation program, but only the Exercise Plus sEMG Biofeedback Group executed therapeutic exercises while the activity of the supraspinatus muscles was monitored using sEMG. Participants were evaluated at enrollment (T0), at the end of 4 weeks of the rehabilitation program (T1), and 8 weeks after T1 (T2), using the following outcome measures: supraspinatus muscle activity as root mean square (RMS), Wheelchair User's Shoulder Pain Index (WUSPI), shoulder abduction, and external rotation range of motion (ROM). The Exercise Plus sEMG Biofeedback Group improved more and faster for all the outcomes compared to the Exercise Group. The monitoring and improvement of supraspinatus muscle activity seems to be an effective way to speed up SP rehabilitation outcomes in WB players, since it makes the performance of therapeutic exercise more precise and finalized, obtaining better and faster results in terms of recovery of shoulder function.

2022 Bern Consensus Statement on Shoulder Injury Prevention, Rehabilitation, and Return to Sport for Athletes at All Participation Levels

There is an absence of high-quality evidence to support rehabilitation and return-to-sport decisions following shoulder injuries in athletes. The Athlete Shoulder Consensus Group was convened to lead a consensus process that aimed to produce best-practice guidance for clinicians, athletes, and coaches for managing shoulder injuries in sport. We developed the consensus via a 2-round Delphi process (involving more than 40 content and methods experts) and an in-person meeting. This consensus statement provides guidance with respect to load and risk management, supporting athlete shoulder rehabilitation, and decision making during the return-to-sport process. This statement is designed to offer clinicians the flexibility to apply principle-based approaches to managing the return-to-sport process within a variety of sporting backgrounds. The principles and consensus of experts working across multiple sports may provide a template for developing additional sport-specific guidance in the future. J Orthop Sports Phys Ther 2022;52(1):11-28. doi:10.2519/jospt.2022.10952.

Effect of conscious abdominal contraction on the activation of periscapular muscles in individuals with subacromial pain syndrome

BACKGROUND

Synergism between shoulder and trunk muscles seems to be effective to increase periscapular muscle activation in asymptomatic subjects. The influence of conscious contraction of the abdominal muscles has not yet been studied in non-athlete subjects with pain. The study aimed to investigate the effect of the instruction for conscious activation of the abdominal muscles on the activity of the scapulothoracic muscles during shoulder exercises in subjects with subacromial pain syndrome.

METHOD

Thirty subjects with unilateral pain (mean age 52 ± 11 years) participated in this study. Three isometric and five dynamic exercises for the scapulothoracic muscles were assessed. The group without instruction just repeated the exercises, while the instruction group was evaluated before and after conscious abdominal training. The linear mixed model analysis was used to compare the muscle activation between groups.

FINDINGS

Differences between groups after the conscious abdominal contraction for activation of middle and lower trapezius on the symptomatic side in the "Full can"(p = 0.03; effect size:0.92 middle trapezius); (p = 0.02; effect size:0.96 lower trapezius) and "Knee Push" (p = 0.01; effect size:0.75 lower trapezius). For asymptomatic side, the exercises "External Rotation Kneeling" (p = 0.04; effect size: 0.81 lower trapezius); (p = 0.00; effect size: 2.09 serratus anterior), "Knee Push" (p = 0.04; effect size:1.24 serratus anterior) and "Wall Slide" (p = 0.01; effect size: 1.03 serratus anterior).

INTERPRETATION

Conscious contraction of the abdominal muscle immediately alter the activation of the serratus anterior muscle during closed kinetic chain exercises on the asymptomatic side and increased activation of trapezius on the symptomatic side during shoulder open kinetic chain exercise.