The effect of an inclined landing surface on biomechanical variables during a jumping task
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Surface electromyographic analysis of the lower trapezius muscle during exercises performed below ninety degrees of shoulder elevation in healthy subjects
by
Robert A. McCabe, MS, PT, OCS, Karl F. Orishimo, MS, Malachy P. McHugh, PhD, Stephen J. Nicholas, MD.
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last modified
2009-10-09 15:17
North Am J Sports Phys Ther. 2007 Feb; 2(1):34-43.
Background. The lower trapezius is an
important muscle for normal arthrokinematics
of the scapula. In the early stages of rehabilitation,
it is generally accepted to perform
exercises with the shoulder kept below 90 deg of
elevation in order to minimize risk for shoulder
impingement. Few exercises for the lower
trapezius have been studied which maintain
the shoulder below 90 deg of humeral elevation.
Objective. To identify therapeutic exercises
performed below 90 deg of humeral elevation
that activate marked levels of lower trapezius
electromyographic (EMG) activity.
Methods. Surface EMG activity of the lower,
middle, upper trapezius, and serratus anterior
was collected bilaterally on fifteen healthy
subjects during four exercises: the press-up,
unilateral scapular retraction with the shoulder
positioned at 80 deg of shoulder flexion, bilateral
shoulder external rotation, and unilateral
scapular depression.
Results. The press-up exercise elicited marked
lower trapezius EMG activity, moderate upper
trapezius EMG activity, and a high ratio of
EMG activity of both the lower and upper
trapezius and moderate activity of the middle
trapezius. Bilateral shoulder external rotation
generated moderate lower trapezius EMG
activity, minimal upper trapezius activity, and
the highest ratio of lower trapezius to upper
trapezius EMG activity. Scapular depression
produced moderate lower trapezius EMG
activity, mimimal upper trapezius EMG activity,
and a moderately high ratio of lower
trapezius to upper trapezius EMG activity.
Discussion and Conclusions. This study
identified two exercises performed below 90 deg
of humeral elevation that markedly activated
the lower trapezius: the press-up and scapular
retraction.