Dance Anatomy & Kinesiology

The Upper Extremity 403

flexion also occurs in pushing motions when the
hand is fixed (closed kinematic chain) and the elbow
is by the side, such as in the up-phase of a push-up
(table 7.10A, p. 432) or press-up (table 7.10C, p.
433). The shoulder flexors—primarily the anterior
deltoid and the pectoralis major (clavicular portion,
table 7.5)—would be used to effect these movements
(table 7.4). Higher ranges of shoulder flexion tend

to be accompanied by slight scapular abduction

(serratus anterior) and upward rotation (trapezius

and serratus anterior, table 7.4) of the scapula

(table 7.3, p. 399). Because of the scapular abduction

that naturally accompanies scapular upward rotation,

the serratus anterior has been shown to play a more

prominent role relative to the trapezius in shoulder

flexion (Rasch, 1989).

Shoulder Complex Movement and Muscles

Used in a Push-Up

Observe a dancer performing a push-up (with the elbows staying in), focusing on the joint motion and

muscles working at the shoulder complex.

• Up-phase. Note that in the up-phase of the push-up the motion at the shoulder is against grav-
  ity. Hence, the joint motion, shoulder flexion, would be produced via concentric contraction of the
  shoulder flexors. Examples of primary shoulder flexors are the anterior deltoid and pectoralis major
  (clavicular) muscles.


• Down-phase. Note that in contrast, during the down-phase, gravity would tend to produce the
  movement at the shoulder joint. Hence, although the joint motion is shoulder extension, the shoulder
  flexors would be working eccentrically to control the lowering of the body and prevent it from falling to
  the ground. So, the same shoulder flexors would be working on both the up- and down-phases of the
  movement—concentrically on the up-phase and eccentrically on the down-phase.


• Scapular stabilization and movement. Now examine the influence of gravity on the scapulae and
  note that the weight of the body will tend to make the scapulae come together or adduct, particularly
  on the down-phase of the movement. Use of the serratus anterior and other scapular abductors to
  keep the scapula “wide” throughout the push-up will help counter this tendency for adduction. Fur-
  thermore, the later stages of shoulder flexion (greater than 60°) tend to be linked with slight scapular
  abduction and upward rotation. Again, the serratus anterior, and to a lesser degree the trapezius, can
  be used to achieve the desired scapulohumeral rhythm.

CONCEPT DEMONSTRATION 7.4

B

A

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