Níveis de excitação muscular de Infra-espinhoso, Trapézios Superior e Inferior em retração escapular sob diferentes níveis de carga em adução em indivíduos com e sem ombro doloroso

Abstract

Introduction: Musculoskeletal pain, especially shoulder pain, occupies a large percentage of medical-hospital care and with the shoulder being the joint complex with the greatest range of motion, which makes it the most unstable. Its structural set promotes its stability and its movements, but muscular alterations can misalign the scapula changing its rhythm, compressing the subacromial space, making it difficult to elevate the arm and causing pain to the individual. Theoretically, an increase in the muscle activity of the upper trapezius associated with a decrease in the activity of its other parts and changes in scapular movements related to the Subacromial Impingement Syndrome. There is no exercise in the literature that combines the activation of the Lower Trapezius and Infraspinatus muscles without increasing the excitation of the Upper Trapezius, thus, an exercise that activates the hypoactivated muscles, without stimulating the already hyperactivated ones, is the ideal proposal. Objectives: To evaluate the excitation levels of Infraspinous, Upper Trapezius and the Lower Trapezius muscles in Scapular retraction exercise with progressive loads of adduction controlled by feedback evaluate which adductor load level would generate the best relation between Upper Trapezius and Lower Trapezius verify the electromyographic differences in individuals with and without shoulders pain. METHODS: forty-two individuals, divided into two groups, with and without shoulder pain, performed scapular retraction exercises controlled by biofeedback. Participants performed a familiarization study of 5 seconds followed by a 3-minute rest, verifying their understanding of the procedure. Then, three maximal voluntary isometric contractions of 5 seconds of each muscle with 5 minutes of rest were collected. Finally, resistance contractions were performed at 60° for 10 seconds at 20%, 30%, 40 and 50% of the Maximum Voluntary Isometric Contraction, with intervals of 20 seconds between tasks, while maximal scapular retraction of the evaluated shoulder was performed. By mean and standard deviation, the data was presented and the classification of differences between groups was done by repeated measures ANOVA. With Holm’s post hoc test, the data were reworked comparing differences between tests avoiding pairwise multiple comparisons with a significant of p <0,05. Results: No differences were observed between the groups, but the results showed that in both groups the objectives were achieved with the exercises. There was an effect on time for all muscles in the group analysis (Upper Trapezius: F = 4,19; p = 0,008/Lower Trapezius: F = 32,7; p = 0,001/Infraspinatus: F = 19,09; p = 0,001). There were differences between pair with values higher than 50% compared to 20% vs. 40%, 20% vs. 50%, 30% vs. 40%, 30% vs. 50% e 40% vs. 50% and 40% vs. 50% and higher values of 40% and 50% MVIC. There was an effect in time between Upper Trapezius-Lower Trapezius ratio (UT: LT) by 20% the UT:LT ratio was lower than 20% and 30%. Conclusion: The scapular retraction movement was significantly beneficial, achieving activation of the Lower Trapezius and Infraspinatus muscles without hyperstimulation of the Upper Trapezius, generating significant differences between muscles.