SELECTIVE ACTIVATION OF THE LOWER TRAPEZIUS MUSCLE IN PATIENTS WITH SHOULDER IMPINGEMENT.

McCabe RA, Tyler TF, Nicholas SJ, McHugh MP

Nicholas Institute of Sports Medicine and Athletic Trauma, New York, NY

PURPOSE: The purpose of this investigation was to determine what therapeutic exercises best isolate the lower trapezius without putting the shoulder in a position of impingement.

METHODS: Surface EMG signals were recorded from the serratus anterior (SRT), upper trapezius (UT), middle trapezius (MT) and lower trapezius (LT) during standard manual muscle testing (MMT) positions and during five selected therapeutic exercises. The five exercises were as follows: 1) standing scapular retraction with the shoulder positioned at zero degrees of elevation, 2) standing scapular retraction with simultaneous bilateral shoulder external rotation against theraband, 3) bilateral standing scapular retraction with simultaneous shoulder depression with the use of theraband, 4) bilateral shoulder elevation in the scapular plane while maintaining maximum scapular depression, 5)standing retraction against theraband with the shoulder positioned at 85 degrees of elevation. All of these exercises were done in a non-impingement range of motion (below 90 degrees).

SUBJECTS: Fourteen subjects (8 female, 6 male) participated in this study. The age of the subjects ranged from 22 to 71. Six of the subjects had a diagnosis of impingement syndrome while eight of the subjects were non-impaired (controls)

ANALYSIS: ANOVA with planned pairwise comparisons was used to test: 1) if the MMTs isolated the muscles they were supposed to target; 2) which exercises best isolate the lower trapezius.

RESULTS: MMT Testing - During the LT MMT, LT EMG was higher than the MT and SRT (p<0.05) in controls but only greater than the MT (p<0.05) in patients. For the MT MMT, MT EMG was greater than the SRT (p<0.05) in controls and both the SRT and UT (p<0.05) in patients. For both the UT MMT UT EMG was greater than the other three muscles (p<0.05) for both controls and patients. Similarly, for the SRT MMT, SRT EMG was higher (p<0.05) than the other three muscles. Exercises - LT EMG (relative to UT activity) was highest for exercises #2, #3 and #4. The most consistent response was seen for exercise #2 where LT EMG was 3.3 times UT EMG compared with 1.7 for exercise #1 (p<0.05), 1.6 for exercise #5 (p<0.01) and only 1.7 for the LT MMT (p<0.05).

CONCLUIONS: The lower trapezius can be selectively recruited in a non-impingement position. In fact, standing scapular retraction with simultaneous bilateral shoulder external rotation against theraband (exercise #2) was better at recruiting the lower trapezius than the standard lower trapezius MMT test.

RELEVANCE: Clinicians are challenged in utilizing therapeutic exercises that selectively recruit the lower trapezius in a non-impingement range of motion. This study identified three such therapeutic exercises for impingement patients.

Journal of Orthopaedic and Sports Physical Therapy, A-45, PL03, 2001.