Background: Although recently it have been shown that shoulder disorders are the third most common musculoskeletal condition in sports, little is understood about the mechanisms and
major muscle patterns that can cause these disorders during tasks of the upper limbs. The abnormal cinematic standard caused by change in the activation of serratus anterior (SA) and upper trapezius
(UT) are evidenced as the responsibles to generate shoulder instability during arm lifting, also reducing the subacromial space. The SA is the main stabilizer of the scapula and to a scapular-humeral
rhythm healthy it is of paramount importance, because there must be a complete interaction between the humerus and scapula to achieve large upper limb degrees of motion. However, if this interaction
do not occurs, there is risk of structures involved in the shoulder complex, what can lead to development of injuries and pathologies, mainly in athletes. Therefore, the objective of this review is to
compare the pattern of SA muscle activation in disorders involving the shoulder complex.
Methods: The instructional guidelines PRISMA (Prefered Reporting Items for Systematic Reviews and Meta-analysis) were followed. The eligibility criteria adopted in accordance with the
PICO (patient, intervention, comparison and outcome) methodology and the keywords selected from these combinations were: Shoulder pain, Shoulder Impingement Syndrome, Frozen Shoulder, Shoulder
Bursitis, Shoulder instability, Glenohumeral instability, Shoulder Dislocation, Massive Rotator Cuff Tear, Cervical Disorders, electromyography, healthy subjects, asymptomatic subjects, pain free
shoulder, scapulathoracic, scapular, serratus anterior muscle, muscle recruitment, muscle activity, muscle activation. Afterwards, the remaining articles were screened on abstract and the remaining
articles have been through selection by methodological quality analysis proposed by CENTRAL COUNSELING INSTITUTION website: https://www.guidelinecentral.com/library/quality-measures/. This search was
applied to Pubmed and Virtual Health Library, and included articles from 1996 till December 2015, written in English.
Results: The results demonstrate that from the 18 articles selected, in 11 an abnormal activity of the SA was found and 7 have shown equal between patients and controls. In 7 studies
it was found a lower muscle activity of SA during tasks of upper limb, other 2 studies found a delay in SA activation, 1 study showing increased activity and 1 that demonstrates an anticipation
disabling muscle during lowering arm phase. In contrast, 5 studies found no significant difference in muscle activation between patients and controls, and other 3 who found no significant difference
related to the previous SA activation time between patients and controls.
Conclusions: Although the results of this systematic review have shown a tendency to abnormal activity of SA in upper limb tasks in individuals with disorders in the shoulder complex,
we can’t reach a consensus on the real role of the SA as the main muscle shoulder complex stabilizer. However, it is clear the importance of a proper muscle pattern for upper limb tasks and sport