***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The aim of this study was to compare the recruitment patterns and latencies of the scapular muscles , as well as the isokinetic performance  of the shoulder rotators in 10 subjects with unilateral impingement syndrome who comprised the impingement group ( IG ) with a control group ( CG ) of 10 asymptomatic subjects . The recruitment patterns and latencies were evaluated by  electromyographic activity during arm elevation in the scapular plane . Isokinetic work ratios of the shoulder rotator muscles were used to analyze muscular performance . A 2 x 2 ANOVA detected that muscular performance and recruitment patterns were similar for both groups and sides . However , the ANOVA revealed a significant side and group interaction , indicating that the scapular muscle latencies of the affected shoulder was greater than that of the nonaffected side only for the IG ( p < .001 ) . These findings indicated that subjects with light to moderate impingement syndrome showed late recruitment of the scapular muscles during arm elevation . However , muscular performance of the shoulder rotator muscles was not affected This paper provides an up-to- date overview of the occurrence , diagnosis , risk factors , prognostic indicators and outcome of shoulder disorder ( SD ) , and of the validity and reproducibility of diagnostic classifications and diagnostic imaging techniques for SD . Furthermore , the available evidence on the effectiveness of non-steroidal anti-inflammatory drugs ( NSAIDs ) , corticosteroid injections and physiotherapy for SD is summarized on the basis of r and omized controlled trials with an acceptable quality of their methods . The annual incidence of SD is estimated at about 7 % , its 1-year period prevalence at about 51 % and its lifetime prevalence at about 10 % . While approximately 50 % of all patients with SD seek medical care , about 95 % are treated in primary health care . Of all new episodes of SD presenting to primary care , approximately 50 % seem to resolve within 6 months , while about 40 % seem to persist for up to 12 months . Several prognostic indicators for a favourable or a poor outcome of SD have been identified , but a comprehensive prognostic model is not available . While evidence for the prognostic validity of popular diagnostic classifications of SD is lacking , their reproducibility has been shown to be poor . The accuracy and clinical usefulness of diagnostic imaging techniques appear to be sufficiently verified for SD in secondary care , while their clinical usefulness in primary care and prognostic validity are not . NSAIDs and steroid injections for SD have been shown to be effective within 6 weeks , but their effect on long-term outcome remains unclear . There is very limited evidence for the effectiveness in SD of physiotherapy , including exercise therapy , ultrasound , electrotherapy , laser , mobilization and manipulation OBJECTIVE Since 2002 , an epidemiologic surveillance system of work-related , upper-limb musculoskeletal disorders ( MSDs ) has been implemented in France 's Pays de la Loire region to assess the prevalence of MSDs and their risk factors in the working population . METHODS The surveillance was based on a network of occupational physicians ( OPs ) and used the recommendations of a group of European experts ( criteria document consensus ) . In 2002 - 2003 , 80 of 400 OPs volunteered to participate . All underwent a training program to st and ardize the physical examination .  Health status was assessed by self-administered question naire and physical examination . Occupational risk factors were assessed by self-administered question naire .  Exposure scores were computed for each anatomic zone by summing the risk factors taken into account by the criteria document . RESULTS More than 50 % of the 2,685 men and women r and omly included in 2002 - 2003 experienced nonspecific musculoskeletal symptoms during the preceeding 12 months and approximately 30 % experienced them in the preceeding week . The prevalence of clinical ly diagnosed MSDs was high : approximately 13 % of workers experienced at least 1 of the MSDs . The most frequent disorder was rotator cuff syndrome followed by carpal tunnel syndrome and lateral epicondylitis . The prevalence of MSDs increased with age and varied widely across economic sectors and occupations . More than half of the workers were exposed to at least 2 risk factors of MSDs . Exposure varied according to industrial activity and occupation . According to the criteria document , a high percentage of MSD cases could be classified as probably work related ( 95 % in men and 89 % in women age < 50 , and 87 % in men and 69 % in women age > 50 ) . CONCLUSION Nonspecific upper-limb symptoms and specific upper-limb MSDs are common in the working population . These results show the need to implement prevention programs in most sectors to reduce the prevalence of MSDs OBJECTIVE To determine the natural history of shoulder pain in the population , and predictors of outcome on the basis of clinical and individual factors . In addition , to determine whether outcome is influenced by the definition of shoulder pain used . METHODS A prospect i ve cohort study , over a 3 year period , of subjects recruited from a cross sectional population screening study of shoulder pain , conducted in the Greater Manchester area of the UK . RESULTS Of 92 subjects classified as having shoulder pain in the cross sectional study , 50 ( 54 % ) reported shoulder pain at followup about 3 years later . In 90 % of cases this was accompanied by some disability specifically relating to the symptoms . Baseline factors that predicted symptoms at followup were : pain ( indicated on a manikin ) within a more narrowly defined shoulder region , shoulder pain related disability , pain on the day of examination , symptoms lasting more than one year , and a high score on the General Health Question naire , a measure of psychological distress . CONCLUSION Shoulder pain in the population is a longterm disabling symptom , although many subjects do not seek early medical consultation . Disability ( independent of whether there was restriction of movement on examination ) is a strong predictor of continuing symptoms . The outcome observed in epidemiological studies of shoulder pain will be influenced by the initial definition of symptoms OBJECTIVE To examine the influence of pain on activation in brief maximal and sustained submaximal isometric abduction in patients with rotator tendinosis of the shoulder . DESIGN R and omized , controlled experimental trial . PARTICIPANTS Ten patients with complaints of at least 3 months ' duration ( median range , 1 to 2 years ) and nine healthy controls . INTERVENTION Patients and controls were r and omized into subacromial local anesthetic injection on 2 different days . METHODS 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 ) . RESULTS 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 . CONCLUSION Pain reduced central motor drive during maximal efforts in the unfatigued state , but no additional reduction was seen after a sustained submaximal contraction Background Altered muscle activity in the scapular muscles is commonly believed to be a factor contributing to shoulder impingement syndrome . However , one important measure of the muscular coordination in the scapular muscles , the timing of the temporal recruitment pattern , is undetermined . Purpose To evaluate the timing of trapezius muscle activity in response to an unexpected arm movement in athletes with impingement and in normal control subjects . Study Design Prospect i ve cohort study . Methods Muscle latency times were measured in all three parts of the trapezius muscle and in the middle deltoid muscle of 39 “ overh and athletes ” with shoulder impingement and compared with that of 30 overh and athletes with no impingement during a sudden downward falling movement of the arm .  Results There were significant differences in the relative muscle latency times between the impingement and the control group subjects . Those with impingement showed a delay in muscle activation of the middle and lower trapezius muscle . Conclusion The results of this study indicate that overh and athletes with impingement symptoms show abnormal muscle recruitment timing in the trapezius muscle . The findings support the theory that impingement of the shoulder may be related to delayed onset of contraction in the middle and lower parts of the trapezius muscle BACKGROUND Scapular function during humeral elevation has been reported in groups with and without shoulder impingement pathology . To date , no one has assessed scapular kinematics during upper extremity loaded tasks that manual wheelchair users must perform on a daily basis . Therefore , the objective of this study was to compare scapular kinematics and muscle activation patterns during two different wheelchair transfers in groups of manual wheelchair users with and without shoulder impingement . METHODS A case controlled study of manual wheelchair users , with and without shoulder impingement was performed . Twenty-three male manual wheelchair users ( 13 without shoulder impingement , 10 with shoulder impingement ) performed transfers toward the involved or dominant limb ( lead limb transfer ) and away from the instrumented limb ( trail limb transfer ) . Position and orientation measures of the thorax , scapula and humerus were obtained using an electromagnetic tracking system .  Muscle activity data were collected using telemetered electromyography . Each subject performed three trials of wheelchair transfers to each side . FINDINGS Manual wheelchair users with impingement performed transfers with reduced thoracic flexion , increased scapular internal rotation , and increased humeral internal rotation as compared to those without impingement . Differences were found between the tasks in the scapular motions and EMG amplitude . Trail limb transfer presented with reduced scapular upward rotation and posterior tip as compared to the lead limb transfer task . Increased muscle activity for the lower trapezius and serratus anterior muscles was demonstrated in the trail limb transfer . INTERPRETATION This study provides the first kinematic description of scapular kinematics during transfer tasks . Shoulder impingement and direction of transfer does affect transfer task performance in manual wheelchair users . Scapular kinematics and muscle patterns during transfers may predispose manual wheelchair users to the development of shoulder pathology 
    Output:
    
Conclusions A difference may exist in EMG activity within some muscles , in particular upper and lower trapezius , between people with SIS and healthy controls .
These muscles may be targets for clinical interventions aiding rehabilitation for people with SIS .