Phases of Throwing

Phases of Throwing

There are 5 main phases of throwing wind up (see below) cocking acceleration deceleration follow-through Biomechanics scapula must work in concert with humerus to maintain glenohumeral stability the entire throwing motion takes approximately 2 seconds with wind up and acceleration phases taking approximately 75% of time (1.5 seconds)
1. Wind Up
Description minimal force on the shoulder during first stage Muscle activity rotator cuff muscles are inactive during this phase
2. Cocking
Sometimes described as 2 sub-phases early cocking peak muscle activation deltoid late cocking high torque phase with maximal shoulder external rotation peak muscle activation supraspinatus infraspinatus teres minor Associated pathology internal Impingement GIRD (glenohumeral internal rotation defect)
3. Acceleration
Description rotates ball to release point Muscle activity early muscle activation triceps late muscle activation pectoralis major latissimus dorsi serratus anterior
4. Deceleration
Description center of gravity moves over plantar foot Muscle activity eccentric contraction of all muscles is required to slow down arm motion highest torque phase Associated pathology recognized as the most harmful phase of throwing associated injuries superior labrum (SLAP lesion) biceps tendon injury brachialis injury teres minor injury
5. Follow-through
Description phase where body rebalances and stops forward motion Muscle activity muscle activity returns to resting levels

TAG

(OBQ11.107) Which of the following is true of the scapula during an overhead throwing motion? Topic

Review Topic

1. It maximally retracts on ball release
2. It protracts during late cocking to prevent impingment on the rotator cuff
3. It must rotate in the cocking and acceleration phases to prevent impingment on the rotator cuff
4. It must remain fixed during the throwing motion to impart maximal energy
5. It is has no effect on concavity-compression

PREFERRED RESPONSE ▶

DISCUSSION: The scapula has an integral role in the overhead throwing motion. It must rotate during cocking and acceleration to clear the acromion to prevent impingement on the rotator cuff. The phases of throwing are seen in Illustration A.

Kibler describes 5 important roles of the scapula during throwing: 1. provide a stable glenohumeral articulation; 2. retraction and protraction; 3. elevation of the acromion; 4. serve as a base for muscular attachment; 5. to be a link in the kinetic chain.

Burkart et al. created the acronym "SICK" scapula (Scapular malposition, Inferior medial border prominence, Coracoid pain and malposition, and dysKinesis of scapular movement) to describe common signs and symptoms in the disabled throwing shoulder. This is felt to be an overuse muscular fatigue syndrome and is a recognized cause of shoulder pain in the throwing athlete.

Incorrect Responses:
1. & 2. The scapula maximally retracts during late cocking and protracts during acceleration and ball release (through activity of the serratus anterior muscle, which is innervated by the long thoracic nerve).
4. The scapula is dynamic and normal motion is needed to generate maximal force transfer.
5. The scapula keeps the humeral head centered thereby increasing concavity-compression and therefore stability.

Illustrations: A

REFERENCES:

1. Kibler WB. The role of the scapula in athletic shoulder function. Am J Sports Med. 1998 Mar-Apr;26(2):325-37. Review PMID:9548131 (Link to Abstract)

2. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology Part III: The SICK scapula, scapular dyskinesis, the kinetic chain, and rehabilitation. Arthroscopy. 2003 Jul-Aug;19(6):641-61. Review. PMID:12861203 (Link to Abstract)

Question Authors:

Patrick McCulloch MD, Ben Taylor MD, John Badylak MD,

Please Rate Educational Value!

3.0

Average 3.0 of 16 Ratings

Level of Evidence 5 and Other Journal Articles (includes Case Reports, Expert Opinions, Personal Observations, and Biomechanic Studies)

Kibler WB. The role of the scapula in athletic shoulder function. Am J Sports Med. 1998 Mar-Apr;26(2):325-37. Review PMID:9548131 (Link to Abstract)
Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology Part III: The SICK scapula, scapular dyskinesis, the kinetic chain, and rehabilitation. Arthroscopy. 2003 Jul-Aug;19(6):641-61. Review. PMID:12861203 (Link to Abstract)

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012

Qbank (1 Questions)

Question Comments

Groups

Evidence & References Show References

Topic Comments