The Chest
• Horizontal Adduction - The pectoralis major
is primarily responsible for horizontal adduc-
tion of the shoulder joint. The pec is also
involved in flexion and extension of the
shoulder joint, although the anterior deltoid
and latissimus dorsi muscles, respectively, are
mechanically more effective at performing
those motions. The pec is involved in inter-
nal rotation of the shoulder, however, this is
a mechanically weak motion and becomes
the limiting factor in strength when combined
with other shoulder motions.
• Scapular Retraction - The position of full
scapular retraction, when maintained, creates
the greatest possible force angles of the pec
throughout the range of motion.
• Range of Motion - With scapular retraction
maintained, horizontal adduction is limited to
approximately 90 degrees (arm straight to the front) and horizontal abduction (achieved
through the eccentric action “lowering of the weight”) is limited by mechanical disadvan-
tage at approximately 0 degrees (upper arm straight out from the shoulder), when pectoralis
work is isolated as the goal.
• Associated Muscles - The anterior deltoid and coracobrachialis are also prime movers for
the motion of horizontal adduction. However, by maintaining motion in the horizontal plane,
scapular retraction, and limited horizontal abduction (limited stretch) the pectoralis major
will be emphasized over the anterior deltoid. The triceps are always involved in pressing
movements as elbow extension is required.
MUSCLES TRAINED
CYBEX VR2 Owner’s Manual
• 10 to 305 Pounds by Fives - The top plate provides a minimum weight of ten pounds.
Subsequent plates in the weight stack are twenty pounds each. Three “slide-on” five pound
incremental plates are securely positioned for easy access and effortless addition thereby
providing 10 to 305 pounds in five pound increments.
Exercise
Page 3-24
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