Middle Trapezius Research Articles

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

ABSTRACT 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.

Electromyographic comparison of exercises for scapulothoracic muscle activation in men with upper crossed syndrome: A cross-sectional study

ObjectiveThis study aimed to determine the optimal exercise for improving Upper Crossed Syndrome (UCS) using electromyographic (EMG) activity of upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) during ten exercises. MethodA cross-sectional study involved 30 male students (mean age: 25.3 ± 2.5 years; height: 176.8 ± 7.2 cm; weight: 77.7 ± 2.5 kg; BMI: 23.8 ± 0.72 kg/m2) with UCS. Participants were selected based on postural assessments (forward head posture ≥44°, rounded shoulder ≥49°, thoracic kyphosis ≥42°). EMG was used to measure activation levels of UT, MT, LT, and SA, and the UT activation ratio relative to MT, LT, and SA during ten exercises. One-way ANOVA was applied for data analysis. ResultsSide-lying external rotation, standing diagonal flexion with Thera-band, and lying prone “V” demonstrated the least UT activity, with the highest MT and LT activation. The standing diagonal flexion with Thera-band elicited the highest SA activity. UT/MT, UT/LT, and UT/SA ratios were less than one in multiple exercises. Significant differences in muscle activation levels and ratios were observed across all exercises (P ≤ 0.05). ConclusionThe findings suggest significant clinical implications for UCS rehabilitation. The identified exercises effectively engage MT and LT while minimizing UT activation, addressing muscular imbalances. Favorable UT/MT, UT/LT, and UT/SA ratios further support these exercises in correcting UCS. These exercises may help counteract the underlying muscular imbalance in UCS by promoting a more balanced activity ratio among the shoulder girdle muscles, potentially improving posture and reducing UCS symptoms.

Threshold and Standard Error of Measurement for Relative Rest Time of Pericervical Muscles During Prolonged Computer-Typing Tasks in Individuals With Neck Symptoms.

Introduction The most common work-related musculoskeletal disorder worldwide is neck pain, especially among individuals who extensively use computers in a seated position. One biomedical cause of this neck pain is the prolonged activity of the muscles around the neck. Electromyography (EMG) has been used to evaluate the frequency and intensity of muscle activity. "Relative rest time (RRT)" is an index derived indicating the proportion of time below a certain threshold to the total task time. This study aimed to investigate the measurement errors and minimum detectable change (MDC) of RRT of the pericervical muscles during prolonged typing tasks in individuals with neck symptoms and to examine the differences in measurement errors at 3 µV and 6 µV thresholds. Methods This test-retest reliability study was conducted twice with a one-week interval to examine measurement errors of the RRT using surface EMG. The number of participants was set to 30 subjects who had neck symptoms with a Neck Disability Index of 16% or higher. The primary outcome measure was RRT of the following: the pericervical muscles of the right side during a 60-minute typing task; the splenius capitis muscle, upper trapezius (UT) muscle, middle trapezius muscle, sternocleidomastoid muscle, serratus anterior muscle, longissimus muscle, and pectoralis major muscle. RRT was calculated as the percentage of time that muscle activity was below the threshold for more than 0.250 seconds continuously during a 60-minute typing task. The standard error of measurement (SEM) and MDC were calculated with the two thresholds of 3 µV and 6 µV. The SEMs of the two thresholds were compared using a paired method. Results Ultimately, the data of 26 participants were analyzed. The SEM (MDC) values of the RRT at the 3 µV and 6 µV thresholds were 19.22 (53.27) and 9.52 (26.39) for the splenius capitis muscle, 3.24 (8.97) and 0.38 (1.05) for the sternocleidomastoid muscle, 15.47 (42.88) and 18.79 (52.08) for the UT muscle, 21.28 (58.99) and 2.28 (6.32) for the middle trapezius muscle, 13.67 (37.90) and 11.64 (32.27) for the serratus anterior muscle, 16.81 (46.60) and 3.32 (9.20) for the longissimus muscle, and 8.97 (24.87) and 4.24 (11.74) for the pectoralis major muscle, respectively. The SEMs of the RRT with the 6 µV threshold were statistically significantly lower than those with the 3 µV threshold in all pericervical muscles, except for the UT muscle. Conclusion This study identified the SEM and MDC of the RRT for the pericervical muscles during prolonged typing tasks in individuals with neck symptoms. Except for the UT muscle, the SEMs of the RRT with the 6 µV threshold were statistically smaller than those with the 3 µV threshold. Therefore, when using the RRT in intervention studies that aim to reduce muscle activity during typing in those with neck symptoms, the 6 µV threshold measurement would be recommended for the RRT of the pericervical muscles except for the UT muscle.

Assessing Scapular Muscle Strength and Force Couple Ratios in Stroke Patients: A Cross-Sectional Study

Introduction: This study quantifies the differences in individual scapular muscle strength in both arms along with obtaining a force couple ratio of scapula stabilizers to gain values in terms of the strength of muscles. Materials and Methods: A quantitative cross-sectional study was done on 30 stroke patients to assess the muscle strength of the serratus anterior, rhomboids, and upper, middle, and lower trapezius (in both shoulders) using a suspension scale. Meanwhile, the muscle force couple ratios were calculated. Results: The results showed significant strength differences between both arms for upper trapezius (P=0.0020), serratus anterior (P=0.018), rhomboids (P=0.001), middle trapezius (P=0.0068), and no difference for lower trapezius (P=0.1746). The mean muscle strength in the non-affected arm is greater than the affected arm. The middle trapezius strength is lowest in the affected arm (0.574 kgf) and the lower trapezius strength is lowest in the non-affected arm (0.767 kgf). The mean force couple ratio for upper trapezius versus lower trapezius was higher in the affected side (10.08) and the non-affected side (7.74). The remaining force couples were similar for both arms. Conclusion: Overall muscle strength of the scapula stabilizers is greater in the non-affected arm than in the affected arm. The strength of the force couple between the upper and lower trapezius is greater in both arms which shows considerable incoordination between the muscles.

Effects of track-based stair climbing robot on muscle activity, usability, and psychological anxiety: a preliminary study

This study investigated the effects of using the LiftCar-150 track-based stair-climbing robot on muscle activity, usability, and psychological anxiety. While stair-climbing robots enhance mobility for individuals with physical disabilities, existing research has predominantly focused on engineering perspectives, with limited attention to user-centered outcomes. Ten healthy participants and an 80 kg dummy rider completed stair-climbing tasks at slow (5 m/min) and fast (7 m/min) speeds. Muscle activity in the middle trapezius (MT), erector spinae (ES), multifidus (MF), gluteus maximus (Gmax), gluteus medius (Gmed), and anterior deltoid (AD) muscles was recorded by electromyography. Usability was evaluated in terms of safety, efficiency, and satisfaction using a 5-point Likert scale, while psychological anxiety was assessed with a visual analog scale (VAS) ranging from 0 to 10. Results showed that during stair ascent, activities of the back extensors (ES and MF) and gluteus muscles (Gmax and Gmed) significantly increased compared to descent, while anterior deltoid activity was higher during descent. Usability scores averaged 4.05 for stability, 4.1 for efficiency, and 3.7 for satisfaction. Perceived psychological anxiety scores were 4.2 ± 0.3 and 5.4 ± 0.5 at slow speed, and 3.5 ± 0.2 and 5.7 ± 0.4 at fast speed during ascent and descent, respectively. While operators recognized the robot’s stability and efficiency, satisfaction levels were neutral, and specific muscle activation was increased. These findings provide essential insights into optimizing the design and usability of stair-climbing robots to better address user needs.

Shoulder Rotation Affects Trapezius Muscle Activity During Shoulder Horizontal Abduction.

Shoulder horizontal abduction exercise in the prone position is effective for strengthening the lower trapezius muscle. However, this exercise is difficult for patients with acute pain or those undergoing initial rehabilitation because of the postural characteristics of the exercise. This study aimed to (1) investigate the effect of a shoulder horizontal abduction exercise when performed with a different amount of shoulder rotation on the trapezius muscle activation and scapular anterior/posterior tilt angle and (2) evaluate the effect of shoulder rotation on the acromiohumeral distance while sitting. Fifteen healthy men performed shoulder horizontal abduction exercise in three shoulder positions (internal rotation, neutral rotation, and external rotation). During exercises, we measured trapezius muscle activity using an electromyography system and scapular anterior/posterior tilt angle using an inclinometer application. We also measured the acromiohumeral distance using real-time ultrasonography before the exercises. Increases in lower trapezius and middle trapezius muscle activities and a decrease in scapular anterior tilt occurred in shoulder external rotation compared with other positions (p<0.001). Shoulder external rotation also significantly increased acromiohumeral distance in the sitting position (p<0.05). We propose that shoulder external rotation effectively and safely increases middle and lower trapezius muscle activities during the sitting shoulder horizontal abduction exercise.

Pool-Based Surfboard Elicits Activation of Posterior Shoulder Muscles During a Surfing Stroke.

Pexa, BS, Johnston, CD, Elder, EE, Ford, KR, Patterson, MQ, and Myers, JB. Pool-based surfboard elicits activation of posterior shoulder muscles during a surfing stroke. J Strength Cond Res 38(7): 1300-1304, 2024-Surfboard paddling may activate posterior shoulder muscles, which are critical to baseball pitchers' injury risk and performance. The purpose of this study was to measure posterior shoulder muscle activation during different phases of the surf stroke (propulsion vs. recovery) on a pool-based surfboard. Twenty healthy active adult subjects completed a familiarization and testing session with the pool-based surfboard. During the testing session, electromyography (EMG) sensors were placed on 6 posterior shoulder muscles: latissimus dorsi, infraspinatus, posterior deltoid, upper trapezius, middle trapezius, and lower trapezius. Subjects completed 4 laps in a pool at 3 separate resistances (low, moderate, and heavy) in a randomized order. The peak EMG signal during each phase (propulsion and recovery) was recorded. A 2-way within subject ANOVA (resistance-by-phase) with post hoc Bonferroni's corrections was used to identify differences in EMG activation. There was a significant main effect of phase for the latissimus dorsi (F = 91.3, p < 0.001), upper trapezius (F = 36.5, p < 0.001), middle trapezius (F = 33.8, p < 0.001), and lower trapezius (F = 21.6, p < 0.001). The latissimus dorsi demonstrated higher activation during the propulsion phase (p < 0.001), and all trapezius muscles demonstrated higher activation during the recovery phase (p < 0.001). There was a significant main effect of resistance for the posterior deltoid (F = 3.4, p = 0.043), with higher muscle activation in the low resistance trials compared with the heavy resistance trials (p = 0.036). Recreationally active individuals demonstrate activation of the posterior shoulder when using a pool-based surfboard. This pool-based surfboard may be beneficial to activate the posterior musculature and may be more accessible than standard surfing to baseball athletes.

The Impact of Different Muscle Relaxation Techniques on the Upper Trapezius and Its Relationship with the Middle Trapezius.

The relaxation of trapezius muscles is widely believed to alleviate fatigue or injury of the trapezius muscles and reduce the risk of shoulder and neck pain. This study aims to examine the effects of different muscle relaxation techniques on the physical properties of the trapezius muscle and to explore how changes in the physical properties of the upper trapezius muscle affect those of the middle trapezius muscle. Twenty-four healthy males (mean age: 23.08 ± 0.97 years; height: 172.42 ± 4.61 cm; weight: 66.38 ± 6.68 kg; and body mass index: 22.30 ± 1.81 kg/m2), randomly divided into four groups: stretching relaxation group (ST, n = 6), mechanical vibration massage (MV, n = 6), pulse massage (PU, n = 6), and control (CO, n = 6). Measurements using the Myoton digital muscle assessment system were conducted daily over 2 weeks. The experimental groups demonstrated a notable decrease in tension and stiffness, accompanied by heightened elasticity in the upper trapezius muscles. Conversely, the control group exhibited contrasting trends. Although no significant variances were detected among the relaxation techniques, all proved efficacious compared to the control group (P < 0.05). Moreover, relaxation of the upper trapezius muscles significantly influenced the middle trapezius muscles (P < 0.05). Various relaxation methods positively influenced trapezius muscle attributes over 2 weeks, with inter-regional effects noted.

Reliability of scapular position and periscapular muscle strength tests in healthy subjects with forward neck and rounded shoulder posture

BACKGROUND: People with forward head posture (FHP) and rounded shoulder posture (RSP) may experience shifts in scapular position and alterations in the strength of the muscles surrounding the scapula. Therefore, a reliable scapula position and scapula muscle strength test are required to identified scapula problem and provided appropriate intervention programs. OBJECTIVE: This study aimed to determine the reliability of scapular position measurements obtained using a modified digital inclinometer and palpation meter, as well as muscle strength using a hand-held dynamometer (HHD) in individuals with FHP and RSP. METHODS: Thirty healthy subjects underwent scapular position tests (upward rotation, anterior tilt, depression, and protraction) and strength tests of periscapular muscles (serratus anterior, upper trapezius, middle trapezius, and lower trapezius) on both the dominant and non-dominant sides. The reliability of the measurements was confirmed by computing the intraclass correlation coefficient (ICC), standard error of measurement (SEM), and minimal clinically important difference (MCID). Test and re-tests were conducted over a period of one week and actual values for each measurement were also obtained and assessed. RESULTS: The ICC ranged from 0.802 to 0.935 for the scapular position tests and from 0.808 to 0.949 for muscle strength tests on the dominant and non-dominant sides. For scapular position tests, SEM values ranged from 0.3 cm to 0.6 cm (protraction and depression), from 1.0∘ to 1.7∘ (upward rotation and anterior tilt) and MCID values ranged from 0.7 cm to 1.6 cm (protraction and depression), from 2.8∘ to 4.7∘ (upward rotation and anterior tilt). Regarding muscle strength tests, SEM and MCID values were in the range 14.4N–27.3N and 39.9N–75.7N, respectively. CONCLUSIONS: Scapular position and periscapular muscle strength can be reproducibly measured in healthy subjects individuals with FHP and RSP. These instruments can hence be recommended for evaluating these functional traits in subjects with FHP and RSP.

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

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. 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). 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). 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). 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.

Evaluation of the metabolic activity of the torn rotator cuff muscles by 18 F-2-deoxy- d -glucose PET-computed tomography scan.

Fatty atrophy and fatty infiltration have been considered as limiting factors for rotator cuff repair. The metabolic activity of the muscle can be measured noninvasively by PET. In our study, we aim to compare the metabolic activity between the shoulders with rotator cuff tears and normal shoulders. All the patients with unilateral full-thickness rotator cuff tears were included. The patients were divided into two groups based on fatty atrophy and the metabolic activities of the rotator cuff muscles, trapezius, and deltoid were calculated using an 18 F-2-deoxy- d -glucose PET-computed tomography scan for comparison. A total of 17 patients were included. The standardized uptake values were compared between the affected shoulder and the normal shoulders. There was a significant increase in uptake in the insertion sites and musculotendinous junctions in the rotator cuff torn group. The standardized uptake values showed no significant difference between the low-grade and high-grade groups. Our first hypothesis was also proven wrong; when we found that there was no statistically significant difference in the metabolic activity in muscle bellies of normal shoulders and those with rotator cuff tears. Our second hypothesis was proven wrong when found that there was no statistically significant difference in the metabolic activities of rotator cuff muscles between high-grade and low-grade fatty atrophy groups. The metabolic activities of the middle deltoid and trapezius are inversely related. Based on the findings of our study, fatty atrophy or fatty infiltration alone cannot be considered a limiting factor for rotator cuff repair.

Periscapular Strength Profile Changes in Collegiate Baseball Pitchers Over the Course of a Season.

Repetitive application of high forces to the shoulder and scapular musculature during the pitching motion over the course of a collegiate baseball season may lead to changes in strength and increased fatigue, potentially predisposing pitching athletes to injury. The purpose of this study was to investigate periscapular strength profiles of Division I collegiate baseball players over the course of a season. This study was a retrospective data analysis of 18 Division I baseball pitchers. Isometric scapular plane abduction (scaption), external rotator, internal rotator, middle trapezius, and lower trapezius isometric strength was measured on throwing arm of each subject using a MicroFET 2 handheld dynamometer. Data were collected in a single session at the preseason, midseason, and postseason of the college baseball season, which spanned a five-month period. A repeated measures ANOVA was utilized to determine if there was a significant change in periscapular strength across the baseball season. Over the three time-points, all strength values decreased for each muscle group, with decreases ranging from 3-14%. Changes in scaption strength values were statistically significant (p=0.018, partial eta squared =0.284) with an 8% reduction over the entire season, specifically with a 5% decline from mid-season to post-season. While external rotator, internal rotator, middle trapezius, and lower trapezius strength values all decreased over the course of the season (range 0.02kg to 1.8kg), these differences were not statistically significant. However, the middle trapezius strength value change (1.3kg loss) exceeded the minimal detectible change. Periscapular muscles in baseball pitchers diminish in strength over the course of a collegiate baseball season. Understanding strength changes over the course of a season may influence training and therapeutic interventions. 3b.

탄성 밴드를 활용한 스탠딩 로우 운동의 그립 형태가 주동근과 안정근의 근활성도에 미치는 영향

This study aimed to investigate the effect of standing row exercise grip on the muscle activity of agonist and stabilizer muscles. 9 men with at least 6 months of resistance exercise experience were selected and performed standing row exercise using an elastic band with a tension of 12 kg. Electromyography was measured during 10 standing row movements according to three types of grips (over, parallel, under), and the muscles of the biceps brachii, rectus abdominis, erector spinae, upper trapezius, middle trapezius, lower trapezius, and latissimus dorsi muscles were measured. The hair roots and latissimus dorsi muscles were measured. For data processing, repeated measures one-way analysis of variance was performed using the SPSS ver 22.0 statistical program. In the biceps brachii, there was a significant difference in the electromyographic response depending on the grip type, and it was highest in the undergrip. Significant differences were also seen in the upper trapezius and middle trapezius muscles, and were highest in the overgrip. This conclusion suggests that due to changes in activated muscles depending on the grip type, the grip type and arm angle should be considered according to the target muscle development when creating a program for row exercise.

Effect of Cervical and Shoulder Complex Exercises on Improvement of Forward Head Posture

Background: Forward head posture is anterior positioning of the head with respect to neck in sagittal plane. Craniovertebral angle is used to measure forward head posture. Craniovertebral angle is formed at the junction of a line drawn from the tragus of the ear through the spinous process of the C7 vertebra and a horizontal line through the C7 vertebra. This study aimed to investigate the effects of cervical and shoulder complex exercises on improvement of forward head posture. Objectives: To improve the forward head posture by- Cervical and shoulder complex exercises. Method: 30 participants, whose craniovertebral angle (CVA) was less than 50° were selected and further divided into experimental group (Group-A) (15 participants) and control group (Group- B) (15 participants). Photos of participants in standing position were taken using mobile camera and craniovertebral angle was measured using autocad software. Experimental group performed exercises such as chin tucks, cervical posterior isometric, scapular retraction exercise, Y to W exercise, middle trapezius fibres muscle strengthening exercise for 6 week interval. Whereas the control group was asked to carry on with routine activities. Pre (0th week ), mid (4th week), and post (6th week ) photos of participants of both groups were taken to see the effect of exercises along with numerical pain rating and neck disability score Results: This study signified that craniovertebral angle (p value=0.001), numerical pain rating scale score ( p value=0.001) and neck disability index scores (p value=0.001) were statistically significant. Conclusion: This study proved that 6 week cervical and shoulder complex exercises protocol has significant effect in improving forward head posture and reducing neck pain and neck disability. Keywords: Autocad software, Craniovertebral angle, chin tucks, forward head posture, neck pain, neck disability

Review and comparison of linear algorithms to quantify muscle fatigue based on sEMG signals

Surface electromyography techniques are widely used in field of motion analysis and ergonomics combining precise muscular activation assessment with low-invasiveness and wearability. The aim of this investigation is to identify the myoelectrical manifestations of fatigue and to compare the effectiveness of sEMG-based quantitative indices for fatigue assessment. The investigated indexes are the ARV and RMS signal amplitudes, the mean frequency, the median frequency, the Dimitrov index, the instantaneous mean frequency and Wavelet distribution-based WIRE51 index. Two different protocols were developed, and the activity of the lateral deltoid and middle trapezius muscles was recorded. The WIRE51 index is found to have the highest sensitivity in the detection of the difference between the repetitions of each exercise for both protocols. Due to the lack of a unified standard for the performance comparison of fatigue indices, a correlation analysis was carried out between the result provided by the indices and the subjective fatigue perception employing the RPE scale.

Acute Effect of Static and Dynamic Stretching on Activating Scapular Stabilizer Muscles During Pull-Up Movement in Gymnasts

Background and Aims Today, there is an argument about the effect of various stretching movements on the performance of athletes. Therefore, this study investigated the acute effect of static and dynamic stretching on muscle activity and co-contraction of scapular stabilizer muscles during pull-ups in gymnasts. Methods According to the inclusion and exclusion criteria, 15 professional gymnasts with a mean age of 23.25±2.57 years, height of 170.93±5.88 cm, and weight of 64.54±5.06 kg were selected as research samples and divided into three subgroups (each with 5 athletes). In the pre-test, subjects performed pull-up activity, and muscle activities of the serratus anterior, upper trapezius, middle trapezius, and lower trapezius muscles were measured using a biometric electromyography device. Then, each subgroup performed a different stretching protocol in each session, and a post-test was conducted like the pre-test. Repeated measures analysis of variance, the Bonferroni post hoc test, and the paired t test were used to test the study hypotheses. Results The results showed that static and dynamic stretching caused a significant decrease and increase in muscle activity in both concentric and eccentric phases, respectively. Also, the results showed that dynamic stretch caused a reduction in co-contraction of the serratus anterior and middle trapezius muscles in both concentric and eccentric phases. In addition, there is a significant difference between the effect of static and dynamic stretch and between dynamic stretch and control on the co-contraction of the serratus anterior and middle trapezius muscles in the concentric and eccentric phases. Conclusion The results showed that the co-contraction of the serratus anterior and middle trapezius muscles decreased after using dynamic stretching. Therefore, considering the importance of muscle co-contraction in the occurrence of shoulder joint injuries and preventing injuries in the shoulder joint of gymnasts, it is suggested that coaches and gymnasts use dynamic stretching exercises more carefully.

High-Density Electromyography Excitation in Front vs. Back Lat Pull-Down Prime Movers.

The current study compared the spatial excitation of the primary muscles during the lat pull-down exercise with the bar passing in front (front-LPD) or behind the neck (back-LPD) using high-density electromyography. Fourteen resistance trained men performed a front-LPD or a back-LPD within a non-fatiguing set with 8-RM as the external load. The muscle excitation centroid of latissimus dorsi, middle trapezius, pectoralis major, biceps brachii, triceps brachii and posterior deltoid muscles were recorded during the ascending and the descending phase. During the descending phase, the front-LPD showed superior excitation of the latissimus dorsi (ES = 0.97) and the pectoralis major (ES = 1.17), while in the ascending phase, the back-LPD exhibited superior excitation of the latissimus dorsi (ES = 0.63), and the front-LPD showed superior excitation of the biceps brachii (ES = 0.41) and the posterior deltoid (ES = 1.77). During the descending phase, the front-LPD showed a more lateral centroid of the latissimus dorsi (ES = 0.60), the biceps brachii (ES = 0.63) and the triceps brachii (ES = 0.98), while the centroid was more medial for the middle trapezius (ES = 0.58). The centroid of the middle trapezius was also more medial in the front-LPD during the ascending phase (ES = 0.85). The pectoralis major centroid was more cranial in the front-LPD for both the descending (ES = 1.58) and the ascending phase (ES = 0.88). The front-LPD appears to provide overall greater excitation in the prime movers. However, distinct spatial excitation patterns were observed, making exercise suitable for the training routine.

Scapular Motor Control and Upper Limb Movement Quality in Subjects with and without Chronic Shoulder Pain: A Cross-Sectional Study

Despite the existence of several studies about the scapula’s position and motion, in shoulder pain conditions, there are still conflicting findings regarding scapular adaptations and reduced research about the scapula’s role during functional tasks. The present study aimed to compare scapular-related kinematic and electromyographic outcomes during different shoulder movements (with and without load) and the drinking task, between symptomatic and asymptomatic subjects. Forty subjects (divided into two groups) participated in this cross-sectional observational study. Scapulothoracic motion, scapulohumeral rhythm, and movement quality (considering trunk compensation, time-to-peak acceleration, and smoothness), as well as the relative surface electromyographic activity and muscle ratio considering the trapezius, serratus anterior, and levator scapulae (LS), were assessed. The symptomatic group presented the following: (1) changes in scapular upward rotation (p = 0.008) and winging (p = 0.026 and p = 0.005) during backward transport and drink phases; (2) increased muscle activity level of the middle trapezius (MT) in all tasks (p &lt; 0.0001 to p = 0.039), of LS during shoulder elevation with load (p = 0.007), and of LS and LT during most of the drinking task phases (p = 0.007 to p = 0.043 and p &lt; 0.0001 to p = 0.014, respectively); (3) a decreased serratus anterior lower portion activity level (SAlow) during shoulder lowering with load (p = 0.030) and drink phase (p = 0.047); and (4) an increased muscular ratio between scapular abductors/adductors (p = 0.005 to p = 0.036) and elevators/depressors (p = 0.008 to p = 0.028). Compared to asymptomatic subjects, subjects with chronic shoulder pain presented scapular upward rotation and winging adaptations; increased activity levels of MT, LT, and LS; decreased activity levels of SAlow; and increased scapular muscle ratios.

Children and adolescents with all forms of shoulder instability demonstrate differences in their movement and muscle activity patterns when compared to age- and sex-matched controls

BackgroundShoulder instability is a complex impairment and identifying biomarkers which differentiate subgroups is challenging. There is limited fundamental movement and muscle activity data for identifying different mechanisms for shoulder instability in children and adolescents which may inform subgrouping and treatment allocation. HypothesisChildren and adolescents with shoulder instability (irrespective of etiology) have differences in their movement and muscle activity profiles compared to age- and sex-matched controls (two-tailed). MethodsYoung people between eight to 18 years were recruited into two groups of shoulder instability (SI) or and age- and sex-matched controls (CG). All forms of SI were included and young people with co-existing neurological pathologies or deficits were excluded. Participants attended a single session and carried out four unweighted and three weighted tasks in which their movements and muscle activity was measured using 3D-movement analysis and surface electromyography. Statistical parametric mapping was used to identify between group differences. ResultsData was collected for 30 young people (15 SI (6M:9F) and 15 CG (8M:7F)). The mean (SD) age for all participants was 13.6 years (3.0). The SI group demonstrated consistently more protracted and elevated sternoclavicular joint positions during all movements. Normalized muscle activity in Latissimus dorsi was lower in the SI group and had the most statistically significant differences across all movements. Where differences were identified, the SI group also had increased normalized activity of their middle trapezius, posterior deltoid and biceps muscles whilst activity of their latissimus dorsi, triceps and anterior deltoid were decreased compared to the CG group. No statistically significant differences were found for pectoralis major across any movements. Weighted tasks produced fewer differences in muscle activity patterns compared to unweighted tasks. DiscussionYoung people with SI may adapt their movements to minimize glenohumeral joint instability. This was demonstrated by reduced variability in acromioclavicular and sternoclavicular joint angles, adoption of different movement strategies across the same joints and increased activity of the scapular stabilizing muscles, despite achieving similar arm positions to the CG. ConclusionYoung people with shoulder instability demonstrated consistent differences in their muscle activity and movement patterns. Consistently observed differences at the shoulder girdle included increased sternoclavicular protraction and elevation accompanied by increased normalized activity of the posterior scapula stabilizing muscles. Existing methods of measurement may be used to inform clinical decision making, however, further work is needed evaluate the prognostic and clinical utility of derived 3D and sEMG data for informing decision making within shoulder instability.

Effect of Therapeutic Exercise in Postural Low Back Pain: A Case Report

Postural low back pain (LBP) is a non-specific LBP defined as pain or discomfort in low back areas caused by incorrect posture for ages. Most patients only experience mild and moderate pain from low back pain, however, it can cause chronic pain and disability for several groups. This case report aims to investigate the effect of therapeutic exercise on posture and pain in postural LBP. A 37-year-old male presented with LBP for 4 months with Numeric Rating Scale (NRS) 7. Physical examination showed impaired posture, wide base gait, limitation ROM of trunk, reduced breathing count test, muscle spasm at upper and lower back areas, positive in Thomas test, Ely test, and hamstring tightness test. The back pain functional scale (BPFS) was 7. The therapeutic exercise program consisted stretching exercises (neck, upper and lower back, hamstring, rectus femoris, iliopsoas muscle), core strengthening, William’s flexion, McKenzie’s, breathing and chest expansion exercise, alongside proprioceptive exercise. One cycle (eight times) of physical modalities, TENS at paralumbal and USD at paracervical, upper and middle trapezius, rhomboid, sternocleidomastoideus, paralumbal, and insertion of hamstring were given. We evaluated the patient’s condition for about 4 months, and the patient showed a good compliance with improvement in pain score, ROM of the trunk, reduced muscle spasm and tightness, improved posture, gait, breathing, and BPFS. The patient can return to do his job again. This case report is able to demonstrate that therapeutic exercise improves clinical and functional conditions. These findings suggest the clinical implications of therapeutic exercise in patients with postural LBP are beneficial.