The initial effects of a sustained glenohumeral postero-lateral glide during elevation on shoulder muscle activity: A repeated measures study on asymptomatic shoulders

Should I prescribe exercise to a patient with an immobilized shoulder? An electromyographic study in patients with unilateral shoulder pain and healthy volunteers

Background

There is limited evidence about exercise performance during postoperative immobilization. This study aimed to quantify the muscle activity in the immobilized shoulder girdle in an abduction and neutral rotation position during a battery of contralateral activities and ipsilateral exercises of the upper limb in healthy volunteers and patients with unilateral shoulder pain (USP).

Methods

Thirty participants were included and grouped as without (N = 17) or with USP (N = 13). Muscle activity (percentage of maximum voluntary isometric contraction (%MVIC)) of the serratus anterior (SA), upper trapezius (UT), lower trapezius (LT) and infraspinatus muscles was assessed during five contralateral activities (during comfortable speed, fast speed and comfortable speed with additional load) and seven ipsilateral exercises.

Results

No differences in % MVIC were found between healthy volunteers and patients with USP on immobilized upper limb exercises and with the contralateral shoulder girdle. General muscle activity was low (<15% MVIC) to moderate (21-40% MVIC). This similarity was maintained at different speeds and with additional load. Adapted lawnmower exercise showed a favorable UT/LT activation ratio.

Conclusion

The study results support the use of all evaluated shoulder exercises, as they have shown low muscle activity, which is important for early rehabilitation phases.

Functional and morphological changes in shoulder girdle muscles after repeated climbing exercise

This study aimed to investigate the acute effect of repeated climbing actions on functional and morphological measures of the shoulder girdle. Fifteen male indoor climbers participated in this study. All the climbers declared route level 6a+, as the best climbing grade (French climbing grade scale). Functional (range of motion - ROM and muscle strength), and morphological measurements (muscle/tendon stiffness and thickness) after a repeated climbing exercise protocol were analysed. The ROM and muscle strength showed significant decreases from baseline to Immediate-Post (IA) as well as significant increases from IA to 1 h-Post for all movements (p ≤ .001 for all). Muscle stiffness showed significant increases from baseline to IA after as well as significant decreases from IA to 1 h-Post for all muscles (p ≤ .001 for all). However, the thickness showed significant increases from baseline to IA for supraspinatus tendon and muscle thickness and occupation ratio (p ≤ .001 for all), while a significant decrease was observed in acromiohumeral distance (p ≤ .001). Significant decreases from IA to 1 h-Post were found for muscles/tendons and occupation ratio (p ≤ .001 for all), while a significant increase for AHD (p ≤ .001). Our data demonstrated acute alterations in tendon thickness due to acute signs of implement symptom in climbers.

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.

Dynamic Spatial Tuning Patterns of Shoulder Muscles with Volunteers in a Driving Posture

Computational human body models (HBMs) of drivers for pre-crash simulations need active shoulder muscle control, and volunteer data are lacking. The goal of this paper was to build shoulder muscle dynamic spatial tuning patterns, with a secondary focus to present shoulder kinematic evaluation data. 8M and 9F volunteers sat in a driver posture, with their torso restrained, and were exposed to upper arm dynamic perturbations in eight directions perpendicular to the humerus. A dropping 8-kg weight connected to the elbow through pulleys applied the loads; the exact timing and direction were unknown. Activity in 11 shoulder muscles was measured using surface electrodes, and upper arm kinematics were measured with three cameras. We found directionally specific muscle activity and presented dynamic spatial tuning patterns for each muscle separated by sex. The preferred directions, i.e. the vector mean of a spatial tuning pattern, were similar between males and females, with the largest difference of 31° in the pectoralis major muscle. Males and females had similar elbow displacements. The maxima of elbow displacements in the loading plane for males was 189 ± 36 mm during flexion loading, and for females, it was 196 ± 36 mm during adduction loading. The data presented here can be used to design shoulder muscle controllers for HBMs and evaluate the performance of shoulder models.

Scapular Retraction under Adduction Load: An Alternative to Overhead Exercises to Activate Infraspinatus, Upper, and Lower Trapezius in Subjects with and without Shoulder Pain

Exercises for lower trapezius (LT) often use overhead positions, causing compressive forces to the subacromial space. Scapular retraction would be an alternative to activate LT muscle. The present study aimed to assess the excitation levels of infraspinatus, upper trapezius, and lower trapezius muscles during a scapular retraction exercise under progressive adduction loads in subjects with and without painful shoulder. Electromyography of infraspinatus (IS), upper trapezius (UT), and LT was recorded during scapular retraction under progressive adduction loads of 42 participants, divided into two groups: with (SP, n = 26) and without shoulder pain (nSP, n = 16). The adduction loads of 20%, 30%, 40%, and 50% of the maximal voluntary contraction (MVC) were applied using a load cell. Normalized electromyography and the ratio between UT and LT (UT:LT) were used for statistical analysis. No differences were observed between groups, but a condition effect occurred for all muscles: UT showed higher values at 50% vs. 20% of MVC (p = 0.004); LT showed higher values on 40% and 50% of MVC (p = 0.001; 0.006). Higher values for IS were noted at 40% of MVC (vs. 20% of MVC; p = 0.04) and at 50% of MVC (vs. 20% of MVC; p = 0.001, vs. 30% of MVC, p = 0.001; vs. 40% of MVC; p = 0.001). UT:LT showed lower values at 50% of MVC (vs. 20% of MVC; p = 0.001 and vs. 30% of MVC; p = 0.016). Scapular retraction with adduction loads at 40-50% is an alternative to overhead exercises aiming to activate the LT and the IS muscles. The exercise ensures higher levels of LT and IS excitation without increasing UT excitation.

Changes in glenohumeral translation, electromyographic activity, and pressure-pain thresholds following sustained or oscillatory mobilizations in stiff and healthy shoulders: Results of a randomized, controlled laboratory trial

STUDY DESIGN

Randomized Controlled Laboratory Study.

BACKGROUND

Posterior glide glenohumeral (GH) mobilizations are utilized to improve motion and decrease pain in patients with shoulder pathologies, thought to be due to capsular stretch and neurophysiologic effects. However, it remains unclear how different GH mobilizations influence mobility, rotator cuff (RC) activity, and pain processing, or if effects are different in stiff (≥15-degree loss of passive motion in any plane) rather than healthy shoulders.

OBJECTIVES

To compare the effects of oscillatory and sustained posterior GH mobilizations on translation, RC activity, and pressure pain threshold (PPT) in stiff and healthy shoulders.

METHODS

Eighty-eight participants, (44 control, 44 stiff shoulders) were randomly assigned to one of two mobilization conditions. Pre-post intervention measurements of PPT, GH translation via ultrasound imaging, and RC activity assessed via electromyography were performed. Sustained or oscillatory grade III posterior GH mobilizations were then provided to all participants. Data were analyzed using tests of difference and regression modeling.

RESULTS

Sustained glides (2.8 ± 3.3 mm) demonstrated significantly greater changes in translation compared to oscillatory glides (1.1 ± 3.9 mm), p = .028. Stiff shoulders demonstrated higher total RC activity than controls both pre (+24.51%, p = .004) and post-intervention (+23.10%, p = .01). Small changes in PPT occurred across all conditions, none reaching clinically meaningful levels.

CONCLUSION

Sustained mobilizations resulted in greater changes in GH translation. RC activity was higher in the stiff shoulder group, and remained higher post-intervention despite gains in GH translation, suggesting a mechanical rather than neurophysiologic effect. There was no meaningful difference in PPT between modes of mobilization.

LEVEL OF EVIDENCE

Therapy, Randomized Controlled Laboratory Study, Level 1b.

FOREARM POSITION MATTERS DURING ECCENTRIC SHOULDER EXERCISES: AN EMG RECRUITMENT STUDY WITH IMPLICATIONS FOR REHABILITATION

Background

Eccentric exercise has demonstrated great utility in the rehabilitation of various shoulder pathologies. Research on the electromyographic (EMG) activity of the shoulder musculature during these activities is limited, however. Furthermore, no studies have observed how forearm positioning during exercise affects EMG output.

Purpose/Hypothesis

The purpose was to examine the degree of specific muscle recruitment among commonly used eccentric exercises in rehabilitation of the upper extremity and shoulder. Secondarily, the authors hypothesized that different hand/forearm positions would alter EMG activity within the targeted musculature during a given exercise.

Study Design

Prospective cross-sectional observation of EMG analysis.

Methods

This study analyzed surface EMG data obtained from 10 healthy individuals during five eccentric exercises of the dominant extremity, performed in a randomized order: side-lying eccentric horizontal abduction (SL ER), half-kneeling weighted ball decelerations (BALL DC), seated eccentric external rotation in scaption (STD ER), standing eccentric external rotation at 0deg (STND ER), supine eccentric external rotation at 90deg (SUP ER). Each exercise was performed with two to three forearm position variants commonly used in clinical environments: neutral, pronation, and/or supination. EMG data were collected from the upper trapezius, infraspinatus, teres minor, latissimus dorsi, and anterior/middle/posterior deltoid. Data were analyzed for each individual exercise and within each muscle using a mixed-model ANOVA repeated across forearm position. Significant interactions were followed by a Bonferroni post-hoc test for pairwise comparisons. Effect size was calculated for all significant pairwise comparisons using a Cohen's d statistic.

Results

Significant differences in EMG activity for the selected musculature exist between forearm positions for four of the five exercises and Cohen's d effect sizes 0.178 - 1.159.

Conclusion

Specific eccentric shoulder exercises activate muscles of the shoulder complex differently based on forearm positioning.

Level of Evidence

Level 2.

The Effect of Shoulder Mobilization on Scapular and Shoulder Muscle Activity During Resisted Shoulder Abduction: A Crossover Study of Asymptomatic Individuals

OBJECTIVE

The primary aim was to investigate the effect of inferior shoulder mobilization on scapular and shoulder muscle activity during resisted shoulder abduction in asymptomatic individuals.

METHODS

This was a lab-based, repeated-measures, crossover, randomized controlled study. Twenty-two participants were recruited. The order of experimental conditions was randomized. Each participant performed 5 repetitions of resisted shoulder abduction before and after the control and mobilization (grade +IV inferior shoulder mobilization, 3 sets, 60 seconds) conditions. Surface electromyography recorded the muscle activity of anterior, middle, and posterior deltoid; supraspinatus; infraspinatus; upper and lower trapezius; serratus anterior; and latissimus dorsi muscles.

RESULTS

Muscle activity levels reduced for infraspinatus (11.3% MVIC, 95% CI: 1.7-20.8), middle (22.4% MVIC, 95% CI: 15.9-28.8) and posterior deltoid (8.7 % MVIC, 95% CI: 4.6-12.9), and serratus anterior (-28.1% MVIC, 95% CI: 15.6-40.8) muscles after the mobilization condition during the eccentric phase of shoulder abduction. No carryover effects were observed, and within-session reliability was excellent (intraclass correlation coefficient scores ranging from 0.94 to 0.99).

CONCLUSION

Our findings suggest that inferior glenohumeral mobilization reduces activity levels of some scapular and shoulder muscles. Given the exploratory nature of our study, changes in muscle activity levels may have been found by chance. Confirmatory studies are required.

Immediate effects of Mulligan's techniques on pain and functional mobility in individuals with knee osteoarthritis: A randomized control trial

BACKGROUND AND PURPOSE

Mulligan's mobilization with movement was shown to be effective when implemented in multimodal therapy for knee osteoarthritis. However, no study has evaluated the Mulligan's technique in isolation and compared the relative effectiveness with sham-controlled interventions. Hence, the present study examined the immediate effects of Mulligan's techniques with sham mobilization on the numerical pain rating scale (NPRS) and timed up and go (TUG) test in individuals with knee osteoarthritis.

METHODS

Thirty participants (mean age: 55.3 ± 8.3 years) with symptoms at the knee and radiographic diagnosis of knee osteoarthritis were randomized into sham (n = 15) and intervention (n = 15) groups. The intervention (I) group received Mulligan's mobilization glides that resulted in relative pain relief for three sets of 10 repetitions. For the sham (S) group, the therapist's hand was placed over the joint surfaces mimicking the pain-relieving glides, without providing the gliding force. The outcome measures NPRS and TUG were recorded by a blinded assessor pre- and post-intervention.

RESULTS

Statistically significant differences were identified between the groups in post-intervention median (interquartile range) NPRS (I group: 4.00 [2.00-5.00]; S group: 6.00 [4.00-7.00]) and TUG scores (I group: 10.9 [9.43-10.45]; S group: 13.18 [10.38-16.00]) with the intervention group demonstrating better outcomes (p < .05). Within-group, the post-intervention scores of NPRS and TUG were significantly lower (p < .05) compared to the pre-intervention scores in the intervention group. In the sham group, a statistically significant pre-post change was noticed only in the NPRS scores but not in the TUG scores.

CONCLUSION

Mulligan's techniques were effective in improving pain and functional mobility in individuals with knee osteoarthritis. The underlying mechanisms for observed effects must be examined further, as participants reported pain relief following sham mobilization.

Análise eletromiográfica de músculos do complexo do ombro durante exercícios de rotação externa com faixa elástica

RESUMO Na artrocinemática do ombro, o manguito rotador atua estabilizando a cabeça umeral em contato com a cavidade glenoidal, enquanto realiza a translação inferior para contrabalancear a força rotacional promovida principalmente pelo deltoide. Exercícios de rotação externa (RE) vêm sendo utilizados na reabilitação de pacientes com disfunções no complexo do ombro buscando restaurar a artrocinemática. Porém, poucos estudos abordam a utilização da faixa elástica e a avaliação dos músculos da cintura escapular, determinantes para uma cinemática adequada. O objetivo deste estudo é comparar a atividade eletromiográfica (EMG) de músculos do complexo do ombro durante exercícios de rotação externa com faixa elástica. Participaram 11 sujeitos do sexo masculino que foram avaliados durante os movimentos de (1) RE em ortostase; (2) RE com abdução de ombro; (3) RE em decúbito lateral (DL). Os músculos avaliados pela EMG foram: (1) trapézio superior (TS); (2) deltoide médio (DM); (3) deltoide posterior (DP); e (4) infraespinal (IN). A resistência foi determinada por uma faixa elástica cinza calibrada com carga de 5% do peso corporal. A análise dos dados foi realizada no software Biomec-SAS e as estatísticas foram calculadas por meio da Anova de medidas repetidas no software SPSS v20.0. Pôde-se constatar que os músculos TS e DM obtiveram maior atividade EMG durante o exercício de RE com abdução de ombro, o músculo DP durante a RE com abdução de ombro e RE em decúbito lateral, enquanto o IN a obteve durante a RE em ortostase e RE em decúbito lateral.

Effectiveness of a tailored rehabilitation versus standard strengthening programme for patients with shoulder pain: a protocol for a feasibility randomised controlled trial (the Otago MASTER trial)

INTRODUCTION

Exercise therapy is the treatment of choice for the management of patients with shoulder subacromial pain. However, we do not know whether a tailored rehabilitation programme is more effective than a standardised strengthening programme. The aim of this feasibility trial is to assess: (1) participant recruitment rate, (2) the proportion of participants enrolled from the total number screened, (3) adherence to the rehabilitation programme, (4) drop-out rates, (5) obtain estimates of adverse reactions to treatment, (6) obtain estimates of intervention effects in order to inform the sample size of the fully-powered randomised controlled trial, (7) conduct a preliminary cost-effectiveness analysis of the standardised strengthening and the tailored rehabilitation interventions.

METHODS

The MAnagement of Subacromial disorders of The shouldER (MASTER) trial, is a two-arm, patient-blinded and assessor-blinded, randomised controlled feasibility trial. Participants will be randomly allocated into one of the interventions group: tailored or standardised rehabilitation. To obtain estimates of intervention effects, we will compare changes in pain and shoulder-related disability scores between the two intervention groups using a repeated mixed-model analysis of variance, with alpha set at 0.05, and power at 80%. Since this is a feasibility study, we will not adjust alpha for multiple comparisons. To determine whether it is feasible to conduct the full trial, we will consider 75% CI as the probability threshold at 3-month follow-up.

ETHICS AND DISSEMINATION

This study was approved by the University of Otago Ethics Committee (Ref: H17/080). Findings from this study will be presented at national and international conferences, and will be submitted for publication in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

ANZCTR: 12617001405303.

Assessment of Whole Body and Local Muscle Fatigue Using Electromyography and a Perceived Exertion Scale for Squat Lifting

This research study aims at addressing the paradigm of whole body fatigue and local muscle fatigue detection for squat lifting. For this purpose, a comparison was made between perceived exertion with the heart rate and normalized mean power frequency (NMPF) of eight major muscles. The sample consisted of 25 healthy males (age: 30 ± 2.2 years). Borg’s CR-10 scale was used for perceived exertion for two segments of the body (lower and upper) and the whole body. The lower extremity of the body was observed to be dominant compared to the upper and whole body in perceived response. First mode of principal component analysis (PCA) was obtained through the covariance matrix for the eight muscles for 25 subjects for NMPF of eight muscles. The diagonal entries in the covariance matrix were observed for each muscle. The muscle with the highest absolute magnitude was observed across all the 25 subjects. The medial deltoid and the rectus femoris muscles were observed to have the highest frequency for each PCA across 25 subjects. The rectus femoris, having the highest counts in all subjects, validated that the lower extremity dominates the sense of whole body fatigue during squat lifting. The findings revealed that it is significant to take into account the relation between perceived and measured effort that can help prevent musculoskeletal disorders in repetitive occupational tasks.

Grade-IV inferior glenohumeral mobilization does not immediately alter shoulder and scapular muscle activity: a repeated-measures study in asymptomatic individuals

OBJECTIVES

To assess: (1) the presence of any carry-over effect between interventions; (2) the immediate effects of inferior shoulder mobilization on shoulder and scapular muscle activity; and (3) to compare muscle activity response between the control and mobilization conditions. Repeated measures, cross-over, pre-post intervention study with sample of convenience.

METHODS

Twenty-two asymptomatic individuals performed 10 repetitions of shoulder abduction before and after the control and mobilization, with a dosage of three sets of 30-s duration, with grade-IV. The order of intervention was randomized. Surface electromyography was used for recording activity of upper and lower trapezius; anterior, middle and posterior deltoids; supraspinatus; infraspinatus; and serratus anterior. Repeated measures mixed-model analysis of variance was used to assess immediate changes in muscle activity levels following inferior shoulder mobilization. Statistical parametric mapping (SPM) was used for comparing muscle activity waveforms between control and mobilization conditions throughout the range of motion.

RESULTS

No systematic changes in muscle activity levels were found between: (1) baseline and follow-up for each condition, at the concentric and eccentric phases of shoulder abduction; (2) control and mobilization conditions during the concentric and eccentric phases of shoulder abduction. SPM results suggested no differences in muscle activity pattern between conditions.

CONCLUSIONS

Inferior shoulder mobilization did not produce immediate effects on shoulder and scapular muscle activity. It is possible that the dose used was insufficient to generate an immediate neuromuscular response to the mobilization.

Differences between clinician- and self-administered shoulder sustained mobilization on scapular and shoulder muscle activity during shoulder abduction: A repeated-measures study on asymptomatic individuals

BACKGROUND

Sustained glenohumeral postero-lateral glide administered by a clinician is commonly used in the management of patients with shoulder pain. This technique reduced shoulder muscle activity in asymptomatic individuals, but it is unknown whether a self-administered version of the mobilization leads to similar neuromuscular response. This study compared the effect of sustained shoulder mobilizations (performed by a physiotherapist) with self-administered mobilization (with a belt) on activity levels of scapular and glenohumeral shoulder muscles.

METHODS

Twenty-two individuals participated in this study, which had a cross-over, repeated measures design. Seven shoulder muscles (upper and lower trapezius, supraspinatus, infraspinatus, posterior deltoid, middle deltoid, and serratus anterior) were monitored using surface electromyography (SEMG) during shoulder abduction performed with a clinician-administered sustained mobilization, and with self-administered sustained mobilization. Muscle activity levels were measured prior, during and after the sustained glide was applied to the shoulder. Mixed-effect models for repeated measures were used for within- and between-condition comparisons.

RESULTS

There was no carry-over effect. Within-condition comparisons suggest that both interventions lead to changes in scapular and shoulder muscle activity levels. No differences between clinician-administered and self-administered mobilizations at intervention and follow-up were found for the monitored muscles, with the exception of upper trapezius.

CONCLUSIONS

In young, asymptomatic individuals, self- or clinician-administered sustained mobilizations reduced activity levels of most scapular and shoulder muscles during shoulder abduction. This effect was observed only while the sustained glides were applied to the shoulder. At the immediate follow-up, muscle activity levels were similar to baseline measurements.

Shoulder muscle activity during the modified dynamic relocation test and side-lying shoulder external rotation: a cross-sectional study on asymptomatic individuals

OBJECTIVES

(1) to compare activity levels between monitored muscles during the dynamic relocation test (DRT); (2) to assess changes in muscle activation variability over 10 trials; (3) to assess within-muscle difference activity levels between the DRT and the unloaded side-lying shoulder external rotation exercise.

METHODS

This is a cross-sectional, laboratory-based, repeated measures study. Thirty asymptomatic individuals performed the DRT and unloaded side-lying external rotation. The order of exercises was randomized. Superficial electromyography was used for recording the supraspinatus, infraspinatus, middle deltoid, posterior deltoid, pectoralis major, and latissimus dorsi muscles. The main outcome measures were mean muscle activity, expressed as % of maximal isometric voluntary contraction.

RESULTS

We found significant between-muscles differences in activity (F_t = 14.11, p < 0.001) during the DRT. Post hoc analysis suggested between-trial variability did not change over the 10 trials, (F = 18.2, p < 0.001). Within-muscle comparisons between the DRT and side-lying shoulder external rotation suggested significant differences between these exercises (F = 32.37, p < 0.001).

CONCLUSIONS

considering the monitored muscles, supraspinatus, infraspinatus, pectoralis major, and latissimus dorsi are the main muscles contracting during the DRT. Of all monitored muscles, supraspinatus muscle was the only one presenting higher activity levels during the DRT when compared to the unloaded side-lying shoulder external rotation.