Muscle activation in the contralateral passive shoulder during isometric shoulder abduction in patients with unilateral shoulder pain (original) (raw)
Related papers
Isometric abduction muscle activation in patients with rotator tendinosis of the shoulder
Archives of Physical Medicine and Rehabilitation, 1997
To examine the influence of pain on activation in brief maximal and sustained submaximal isometric abduction in patients with rotator tendinosis of the shoulder. Randomized, controlled experimental trial. Ten patients with complaints of at least 3 months' duration (median range, 1 to 2 years) and nine healthy controls. Patients and controls were randomized into subacromial local anesthetic injection on 2 different days. The uninvolved shoulder was tested first, elbow flexed 90 degrees, shoulder abducted 45 degrees. The protocol consisted of three brief maximal voluntary contractions (MVCs), followed by a sustained submaximal contraction until exhaustion and three MVCs during a 20-minute recovery period. Electromyography (EMG) was obtained bilaterally from the supraspinatus, infraspinatus, upper trapezius, and middle deltoid muscles. Pain was scored on a visual analogue scale (0 to 100). Mean pain rating on MVC of the involved side of patients was reduced from 28 to 10 by subacromial injection. Mean MVC force improved from 163N to 184N (95% confidence interval for the difference, 14 to 29N). The accompanying EMG amplitude during MVC increased significantly in three of the four muscles examined. Pain, force, and EMG of the uninvolved side and in controls were unaltered. Endurance time and EMG (given as microV) during the submaximal contraction were not influenced by pain. MVC did not fully recover during the postexhaustive period, while the corresponding EMG amplitudes were comparable to values in unfatigued muscle. Pain reduced central motor drive during maximal efforts in the unfatigued state, but no additional reduction was seen after a sustained submaximal contraction.
European Journal of Applied Physiology, 2008
Altered shoulder muscle activity is frequently believed to be a pathogenetic factor of subacromial impingement (SI) and therapeutic interventions have been directed towards restoring normal motor patterns. Still, there is a lack of scientific evidence regarding the changes in muscle activity in patients with SI. The aim of the study was to determine and compare the activity pattern of the shoulder muscles in subjects with and without SI. Twenty-one subjects with SI and 20 healthy controls were included. Electromyography (EMG) was assessed from eight shoulder muscles from both shoulders during motion. In the symptomatic shoulder, there was a significantly greater EMG activity during abduction in the supraspinatus and latissimus muscles and less activity in serratus anterior compared to the healthy subjects. During external rotation, there was significantly less activity of the infraspinatus and serratus anterior muscles on the symptomatic side compared to the healthy subjects. On the asymptomatic side, the groups showed different muscle activity during external rotation. Our findings of an altered shoulder muscle activity pattern on both the symptomatic and asymptomatic side in patients indicate that the different motor patterns might be a pathogenetic factor of SI, perhaps due to inappropriate neuromuscular strategies affecting both shoulders.
The effect of chronic shoulder pain on maximal force of shoulder abduction
Journal of Bodywork and Movement Therapies, 2014
The aim of this study was to determine if chronic shoulder pain had an effect on arm abduction strength and recruitment strategies of the serratus anterior, middle deltoid, and upper trapezius. Method: The maximal isometric force at 30 arm abduction and the electromyographic activity of the serratus anterior, middle deltoid, and upper trapezius were recorded for 14 subjects with unilateral chronic shoulder pain and 11 healthy subjects. Results: Relative to the group without pain, the group with chronic shoulder pain showed no significant difference in maximal force production during isometric arm abduction. The ManneWhitney tests showed no differences in the activation of the serratus anterior, middle deltoid, and upper trapezius between the two groups. Discussion and conclusion: Subjects with chronic shoulder pain of mild to moderate intensity showed no difference from healthy subjects in arm abduction maximal strength, and recruitment patterns of serratus anterior, middle deltoid, and upper trapezius. ª
European journal of applied physiology, 2015
Shoulder pain is often a challenging clinical phenomenon because of the potential mismatch between pathology and the perception of pain. Current evidence clearly emphasizes an incomplete understanding of the nature of shoulder pain. Indeed, the effective diagnosis and treatment of shoulder pain should not only rely upon a detailed knowledge of the peripheral pathologies that may be present in the shoulder, but also on current knowledge of pain neurophysiology. To assess and treat shoulder pain, a comprehensive understanding of the way in which pain is processed is essential. This review reflects modern pain neurophysiology to the shoulder and aims to answer the following questions: why does my shoulder hurt? What is the impact of shoulder pain on muscle function? What are the implications for the clinical examination of the shoulder? And finally, what are the clinical implications for therapy? Despite the increasing amount of research in this area, an in-depth understanding of the b...
EMG and strength correlates of selected shoulder muscles during rotations of the glenohumeral joint
Clinical Biomechanics, 2000
Objective. To identify activation patterns of several muscles acting on the shoulder joint during isokinetic internal and external rotation. Design. Combined EMG and isokinetic strength analysis in healthy subjects. Background. EMG studies of the shoulder region revealed intricate muscular activation patterns during elevation of the arm but no parallel studies regarding pure rotations of the joint could be located. Methods. Fifteen (n 30 shoulders) young, asymptomatic male subjects participated in the study. Strength production during isokinetic concentric and eccentric internal and external rotations at 60 and 180°/s was correlated with the EMG activity of the rotator cu, biceps, deltoid and pectoralis major. Analysis of the smoothed EMG related to the timing of onset of the signal and to the normalized activity at the angle of the peak moment. Determination of the association between the EMG and the moment was based on strength ratios. Results. Findings indicated that for both types of rotations, the rotator cu and biceps were active 0.092 0.038±0.215 0.045 s prior to the initiation of the actual movement and 0.112±0.034 s prior to onset of deltoid and pectoralis major activity. These dierences were signi®cant in all of the eight conditions (P < 0.05). In terms of the strength ratios, strong association was found between electrical activity and moment production in the subscapularis and infraspinatus (r 2 0.95 and 0.72, respectively) at the low and high angular velocities. Conclusions. Prior to actual rotation of the shoulder joint, normal recruitment of the rotator cu and biceps is characterized by a non-speci®c presetting phase which is mainly directed at enhancing the joint`stiness' and hence its stability. Once movement is in progress, the EMG patterns of these muscles become movement speci®c and are correlated with the resultant moment. Relevance Muscular dysfunction relating to delayed onset activity or altered activation patterns, due to pain, perturbed mechanics or disturbed neural activation have been implicated as concomitant factors in other joint associated pathologies. Through highlighting the role of the rotator cu in shoulder joint rotations, this study lends further support to the argument that a parallel situation may prevail with respect to shoulder joint dysfunction. This could lead to the development of rehabilitation protocols aimed speci®cally at redressing such dysfunction.
Biomechanisms
This study aimed to clarify the effect of repetitive rotator cuff exercise on corticospinal tract excitability, which concerning the control of the external rotator muscles during shoulder joint abduction. We examined the corticospinal tract excitability before and after the rotator cuff exercise by using transcranial magnetic stimulation(TMS). The exercise was repeated 100 times every 15 minutes for total of 300 repetitions. The corticospinal tract excitability during shoulder joint abduction was measured by using motor-evoked potentials(MEPs). TMS was applied to induce MEPs in the infraspinatus, middle deltoid, posterior deltoid, and lower trapezius muscles during the isometric shoulder joint abduction. Abduction was performed 20°in the scapular plane. MEPs were measured twice before exercise(pre1, pre2), immediately after each exercise(exercise1, exercise2, exercise3), further, and 30 minutes and 60 minutes after the third exercise ended(post30, post60). The MEP amplitude of the infraspinatus muscle was significantly increased until 60 minutes after the exercise ended in comparison with that measured at pre1, whereas there was no significant difference in the MEP amplitudes of the other muscles. The present study demonstrated that the corticospinal tract excitability of the infraspinatus muscle was increased during shoulder joint abduction after the intervention exercise.
Electromyographical comparison of four common shoulder exercises in unstable and stable shoulders
Rehabilitation research and practice, 2012
This study examines if electromyographic (EMG) amplitude differences exist between patients with shoulder instability and healthy controls performing scaption, prone horizontal abduction, prone external rotation, and push-up plus shoulder rehabilitation exercises. Thirty nine subjects were categorized by a single orthopedic surgeon as having multidirectional instability (n = 10), anterior instability (n = 9), generalized laxity (n = 10), or a healthy shoulder (n = 10). Indwelling and surface electrodes were utilized to measure EMG activity (reported as a % of maximum voluntary isometric contraction (MVIC)) in various shoulder muscles during 4 common shoulder exercises. The exercises studied effectively activated the primary musculature targeted in each exercise equally among all groups. The serratus anterior generated high activity (50-80% MVIC) during a push-up plus, while the infraspinatus and teres major generated moderate-to-high activity (30-80% MVIC) during both the prone hori...
Journal of Orthopaedics and Traumatology
Background Rotator cuff muscles stabilise the glenohumeral joint and contribute to the initial abduction phase with other shoulder muscles. This study aimed to determine if the load-induced increase in shoulder muscle activity during a 30° abduction test is influenced by asymptomatic or symptomatic rotator cuff pathologies. Materials and Methods Twenty-five patients with unilateral rotator cuff tears (age, 64.3 ± 10.2 years), 25 older control subjects (55.4 ± 8.2 years) and 25 younger control subjects (26.1 ± 2.3 years) participated in this study. Participants performed a bilateral 30° arm abduction and adduction movement in the scapular plane with handheld weights (0–4 kg). Activity of the deltoid, infraspinatus, biceps brachii, pectoralis major, latissimus dorsi and upper trapezius muscles was analysed at maximum abduction angle after normalisation to maximum voluntary contraction. Shoulders were classified into rotator cuff tendinopathy, asymptomatic and symptomatic rotator cuff ...
Clinical Anatomy, 2011
Although flexion is a common component of the routine clinical assessment of the shoulder the muscle recruitment patterns during this movement are not clearly understood making valid interpretation of potential muscle dysfunction problematic. The purpose of this study was to comprehensively examine shoulder muscle activity during flexion in order to compare the activity levels and recruitment patterns of shoulder flexor, scapular lateral rotator and rotator cuff muscles. Electromyographic (EMG) data were recorded from 12 shoulder muscles sites in 15 volunteers. Flexion was performed in standing in the sagittal plane at no load, 20%, and 60% of each subject's maximum load. EMG data were normalized to maximum values obtained during maximum voluntary contractions. Results indicated that anterior deltoid, pectoralis major, supraspinatus, infraspinatus, serratus anterior, upper, and lower trapezius were activated at similar moderate levels. However, subscapularis was activated at low levels and significantly lower than supraspinatus and infraspinatus. Similar activity patterns across time were demonstrated in the muscles that produce flexion torque, laterally rotate the scapula, as well as supraspinatus and infraspinatus, and did not change as flexion load increased. The onset of activity in supraspinatus and anterior deltoid occurred at the same time and prior to movement of the limb at all loads with infraspinatus activity also occurring prior to movement onset at the medium and high load conditions only. Posterior rotator cuff muscles appear to be counterbalancing anterior translational forces produced during flexion and it would appear that supraspinatus is one of the muscles that consistently ''initiates'' flexion. Clin. Anat. 24:619-626, 2011. V V C 2011 Wiley-Liss, Inc.