Abstract
Reduction in isometric strength of the scapulohumeral muscles is a commonly seen impairment in overhead athletes afflicted with shoulder impingement syndrome (SIS). The purpose of this study was to compare the effects of two different treatment programs: progressive resistance exercises plus manual therapy (PRE plus MT) and motor control exercises (MCE), on isometric strength of upper trapezius (UT), middle trapezius (MTr), lower trapezius (LT), serratus anterior (SA), supraspinatus (Supr.), anterior deltoid (A.D), and latissimus dorsi (LD). 80 male university-level overhead athletes clinically diagnosed with SIS were randomly allocated into either of the two groups: PRE plus MT and MCE group. Athletes in the PRE plus MT group underwent graduated exercises with resistance elastic band, stretching exercises, and mobilization of the thoracic and shoulder joints. MCE group was submitted to motor control exercises in varied planar positions. Athletes in both groups underwent management 3 times a week for 8 weeks. Isometric strength of UT, MTr, LT, Supr, A.D, SA, and LD was measured at three-time points: baseline, 4th week, and 8th week. Relative to baseline, both interventions were found to be effective in increasing and optimizing the isometric strength of muscles (p < 0.05) except for supraspinatus in the MCE group (p > 0.05). However, athletes in PRE plus MT group presented a more pronounced increase in isometric strength than those in the MCE group. Between groups analysis found the largest isometric strength improvement in PRE plus MT group for A.D, followed by Supr. and UT muscles (p < 0.05; effect size: 0.39 to 0.40). The study concluded that compared to MCE, PRE plus MT provides greater improvement in the isometric strength of scapulohumeral muscles.
Highlights
Shoulder impingement syndrome (SIS) is a common musculoskeletal condition seen in overhead athletes, and it affects a large number of athletes at some point during their career [1]
Athletes were recruited in the study as per the following criteria: (i) 17-35 years of age; (ii) male overhead athletes playing competitive sports like volleyball, tennis, baseball, cricket, swimming, badminton, and basketball for at least 6 hours a week; (iii) shoulder impingement symptoms duration of ≥1 month; (iv) pain rating on visual analog scale (VAS) of less than or equal to 7/10; (v) athletes agreeing to participate for the entire duration of treatment; and (vi) athletes were recruited on fulfilling a minimum of 2 out of 5 diagnostic criteria for SIS
The mean changes in the isometric strength measured from baseline to the 4th week of intervention were found significant (p < 0:05) for all muscles in both the groups except for supraspinatus muscle in the motor control exercises (MCE) group (Table 5, Figure 2)
Summary
Shoulder impingement syndrome (SIS) is a common musculoskeletal condition seen in overhead athletes, and it affects a large number of athletes at some point during their career [1]. Reduction in isometric strength of shoulder external rotation and abduction are the two most cardinal features of SIS. The reduction in isometric strength could be firstly due to muscle deconditioning following SIS onset and secondly related to deficits in motor control of the muscles [4, 5]. Lack of motor control changes the muscle activation levels and decreases the coordination between the glenohumeral and scapulothoracic muscles during the overhead elevation motion, and eventually, it contributes to the reduction of isometric strength [5]. Isometric strength changes up to 33% and 29% in shoulder external rotation and shoulder abduction, respectively, have been reported in studies [6]. There is a paucity of evidence due to a limited number of studies that have examined isometric strength improvement as their primary outcome
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