Abstract
Overhead athletes require strenuous shoulder activity in nonneutral cervical
spine positions to eccentrically decelerate the throwing/striking arm following
ball release/contact. We therefore aimed to compare eccentric shoulder rotation
strength through a 90° arc between neutral and rotated positions. Fifty-two
participants (19 M, 34 F 170±10 cm; 73±18 kg, 21.9±2.9 years) without shoulder
or cervical spine pathology participated. Isokinetic eccentric shoulder rotation
strength was measured through a 90° arc with the shoulder elevated 90° in
frontal plane (frontal plane), and 45° anterior to the frontal plane (scapular
plane) in neutral and rotated cervical spine positions. Cervical spine position
was obtained by instructing participants to maximally rotate their respective
side. Frontal plane eccentric external rotated strength differed between neutral
and contralaterally positions in the first 10° of the motion, near forearm
vertical (p+=+0.029). Internal rotation strength differed between neutral and
contralaterally rotated positions from 55–60° external rotation (p+=+0.004).
Scapular plane eccentric external rotation differed between cervical positions
between 21–67° shoulder external rotation (p<0.001). Scapular plane internal
rotation strength differed between cervical positions between 22–60° shoulder
external rotation (p<0.001). In populations requiring strenuous use of their
shoulders in altered cervical spine positions, sports medicine clinicians should
consider including strength testing that reflects the functional positions of
their patients during an orthopedic examination.
Keywords
dynamometry - neck - spinal posture - strength testing