Deltoid Development Through Proper Biomechanics!

Whenever we engage in a lifting movement, we utilize the deltoid muscles. Learn how to get well-developed deltoids with biomechanics!

Although the pectoralis major muscles of the chest and the biceps brachii muscles of the arms are undoubtedly the areas that receive the most praise and adoration, I believe that symmetrical, well-developed deltoid muscles are what differentiate a good physique from a great physique.

Whenever we engage in a lifting movement, we utilize the deltoid muscles. Generally, the larger trapezius muscle stabilizes the scapula as the deltoid pulls on the humerus. The deltoid muscle is made up of three heads: the anterior deltoid, the middle deltoid and the posterior deltoid. The fibers of the anterior deltoid are involved in flexion, internal rotation and horizontal adduction of the glenohumeral joint.

The fibers of the middle deltoid are involved in abduction of the glenohumeral joint. The fibers of the posterior deltoid are involved in abduction, extension, and horizontal abduction of the glenohumeral joint.

The Biomechanics Of The Deltoids

Origin Insertion Action Innervation
Anterior lateral third of clavicle

Lateral aspects of acromion

Inferior edge of spine scapula

Deltoid tuberocity on lateral humerous

Deltoid tuberocity on lateral humerous

Deltoid tuberocity on lateral humerous

Flexion, horizontal adduction and internal rotation of glenohumeral joint

Abduction of the glenohumeral joint

Abduction, extension, horizontal abduction and external rotation of glenohumeral joint

Axillary nerve (C5, C6)

Axillary nerve (C5, C6)

Axillary nerve (C5, C6)

Selected Exercises For Well-Developed Deltoids

Seated Barbell Press - View Exercise

Proper Positioning:

  • Assume a seated position on a vertical shoulder press bench.
  • Place your feet firmly on the floor.
  • Press shoulder blades and sacrum firmly against the bench.
  • Grasp the bar with a pronated grip slightly wider than shoulder width apart while still on the rack.
  • Press the bar overhead off of the support rack until the elbows are fully extended. (starting position)


  • Lower the bar down slowly, initiating elbow flexion.
  • Keep the wrists in a rigid position, palms facing forward, with the shoulders and sacrum presses firmly against the bench.
  • Continue to lower the bar until it descends to clavicle level.
  • Press the bar upward, initiating elbow extension.
  • Do not arch the back while pressing up.
  • Continue to press up until you return to starting position.

Essential Tips:

  • Do not rise out of the bench.
  • Keep the elbows directly under the hands.
  • Keep the wrist in a rigid position throughout the movement.
  • Do not arch the back during execution.

Barbell Upright Row - View Exercise

Proper Positioning:

  • Stand with feet slightly wider than shoulder width apart and with knees slightly flexed.
  • Grasp the bar with a pronated grip with the bar resting against the front of your thighs.
  • Grasp the bar with approximately 6-inches between the hands.
  • The elbows should fully extend with elbows pointed directly outward.


  • Begin by pulling the bar up along the body.
  • Keep the body erect with the knees slightly flexed.
  • Continue to pull the bar up until the bar reaches clavicle level.
  • The hands should be at clavicle level with the elbows pointed up and out at approximately ear level.
  • 5. Slowly allow the bar to travel along the body back to the starting position.

Essential Tips:

  • Do not bounce the bar to initiate the upward movement.
  • Do not swing the weight or rise on the toes.
  • Do not assist the movement with the lower body.
  • The wrist should stay in a rigid position throughout the movement.

Dumbbell Medial Deltoid Lateral Raise - View Exercise

Proper Positioning:

  • Stand with the feet planted firmly on the ground approximately shoulder width apart.
  • The knees should be slightly flexed.
  • With the palms facing in against the outer thighs, grasp the dumbbells with a natural grip.
  • The elbows should be pointed directly back.


  • Begin by laterally raising the arms by contracting the medial deltoids.
  • Continue to contract the medial deltoids until they are approximately parallel to the floor.
  • Slowly lower the arms back to the starting position.

Essential Tips:

  • Do not swing the weight.
  • Do not come up on toes to move the weight.
  • Lead with the elbows, not the hands. 4. The hand position should have the pinky finger higher than the thumb (similar to that of pouring a pitcher of water).
  • Elbows should not rise above shoulder level with the hands being slightly lower than the elbows.

A final key point to recognize is the proper stretching of the deltoid muscle. Taking the humerus into horizontal abduction or by horizontal extension and adduction stretches the anterior deltoid. To focus on the middle fibers, the humerus must be placed in adduction behind the back. Finally, to stretch the posterior fibers, you must place these fibers in horizontal adduction.

Click To Enlarge!

By having a stronger comprehension of the proper biomechanics of the deltoid muscles, as well as correct methods in which to stretch this muscle, you can successfully design a program in which you can optimize your deltoid muscle potential. Preparation, persistence and hard work will help you reach your potential.

If you have any questions or comments regarding this article, please contact

Patrick Gamboa, BS MSS
International Sports Sciences Association
The World Leader In Fitness Certifications - Since 1988
Director of Educational and Technical Support
Editor-in-Chief of ProTrainer Online Magazine
1(800) 892-4772
805-884-8111 (international)


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