Scapular muscular activity with shoulder impingement syndrome during lowering of the arms.
OBJECTIVE
To compare isolated electromyographic (EMG) activity of the serratus anterior, upper, middle, and lower trapezius, as well as the coactivation of the upper and middle trapezius/serratus anterior in subjects with and without shoulder impingement syndrome (IS), during lowering of the arms.


METHODS
Cross-sectional study.


METHODS
University laboratory.


METHODS
Twenty young adults, 10 with unilateral IS degree I or II (mean age 28.6 +/- 5.89 years) and 10 without any complaints or history of previous shoulder lesions (mean age 29.0 +/- 5.35 years), matched by gender, age, and levels of physical activity.


METHODS
Isolated EMG activity of the serratus anterior, upper, middle, and lower trapezius, as well as the coactivation of the upper trapezius and middle trapezius/serratus anterior. The EMG activity was quantified by root mean square calculations and normalized by maximal voluntary isometric contractions.


RESULTS
Significant differences between groups were found only for the coactivation of the middle trapezius/serratus anterior (F = 6.81; P = 0.02). No significant differences were found between sides (F = 0.05; P = 0.83) nor for interactions between sides and groups (F = 3.85; P = 0.07).


CONCLUSIONS
These findings pointed out the importance of evaluating the lowering of the arms in individuals with IS and suggested that measures of coactivation, besides reflecting the real purpose of the muscular actions during functional activities, are more sensitive to detect changes between groups. The evaluation of the coactivation of the middle trapezius/serratus anterior should be included in clinical assessment of individuals with IS and investigations on the etiology and progression of IS.
de Morais Faria
Christina Danielli Coelho
CD
Department of Physical Therapy, Universidade Federal de Minas Gerais, Minas Gerais, Brazil.
Teixeira-Salmela
Luci Fuscaldi
LF
de Paula Goulart
Fátima Rodrigues
FR
de Souza Moraes
Geraldo Fabiano
GF
D000328:Adult; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D018583:Pliability; D012540:Scapula / Q000503:physiopathology*; D019534:Shoulder Impingement Syndrome / Q000175:diagnosis / Q000503:physiopathology*