An electromyographic assessment of the "bear hug": an examination for the evaluation of the subscapularis muscle.
OBJECTIVE
The lift-off and belly-press tests are common tests for evaluation of the subscapularis. We compared these tests with the recently developed bear-hug test by assessing electromyographic (EMG) activity of the shoulder internal rotators during examination.


METHODS
Twenty-one healthy male volunteers (mean age, 22.95 +/- 3.71 years; mean weight, 73.48 +/- 6.93 kg; mean height, 68.76 +/- 2.26 cm) with no previous history of shoulder surgery or injury participated in the study. Fine-wire and surface EMG activity of the glenohumeral joint internal rotators (i.e., upper and lower subscapularis, pectoralis major, and latissimus dorsi) was recorded while 5 subscapularis tests were being performed (bear hug at 0 degrees, 45 degrees, and 90 degrees; lift off; and belly press). Peak EMG values were normalized to the maximum voluntary isometric contraction (MVIC) for each muscle. A 4 (muscle) x 5 (test) analysis of variance with repeated measures on test was used to analyze peak EMG activity (percentage of maximum voluntary isometric contraction). Follow-up univariate analysis of variance and Tukey post hoc analyses were performed for each of the 5 tests.


RESULTS
The bear-hug test performed at 45 degrees of shoulder flexion showed significantly greater peak EMG activity in the upper subscapularis (107.64% +/- 63.52%) and lower subscapularis (85.75% +/- 64.69%) compared with the pectoralis major (41.43% +/- 25.42%) and latissimus dorsi (20.32% +/- 15.70%) (P < .05). The bear-hug test performed at 90 degrees of shoulder flexion showed significantly greater peak EMG activity in the lower subscapularis (166.0% +/- 132.71%) compared with the upper subscapularis (97.23% +/- 70.78%), pectoralis major (50.63% +/- 29.60%), and latissimus dorsi (17.56% +/- 13.64%) (P < .05). The belly-press test showed significantly greater peak EMG activity in the upper subscapularis (77.88% +/- 53.23%) and lower subscapularis (71.82% +/- 46.49%) compared with the pectoralis major (18.49% +/- 14.85%) and latissimus dorsi (34.85% +/- 27.73%) (P < .05).


CONCLUSIONS
The bear-hug examination performed at 45 degrees of shoulder flexion and the belly-press test may be valuable diagnostic tools in the clinical evaluation of the upper subscapularis muscle. In addition, the bear-hug test at 90 degrees of shoulder flexion may be a valuable diagnostic tool in assessing the clinical function of the lower subscapularis.


CONCLUSIONS
The bear-hug examination performed at specific degrees of shoulder flexion may be a valuable way to assess the function of the subscapularis muscle.
Chao
Simon
S
Department of Orthopaedic Surgery, Temple University Hospital, Philadelphia, Pennsylvania, USA. schao@temple.edu
Thomas
Stephen
S
Yucha
David
D
Kelly
John D
JD
Driban
Jeff
J
Swanik
Kathleen
K
D000328:Adult; D004576:Electromyography / Q000379:methods*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D012016:Reference Values; D012540:Scapula / Q000502:physiology*; D012785:Shoulder Joint / Q000502:physiology*; D013314:Stress, Mechanical; D055815:Young Adult