Special Topics (Scapular Dyskinesia & Throwing)

Scapular Dyskinesis

altered movement or position of the scapula

winging or dysrhythmia of scapula during shoulder flexion and abduction

What does the scapular dyskinesis test observe?

Scapular Winging

excessive movement of medial aspect of scapula on thorax

Scapular Dysrhythmia

jagged movement of scapular (timing and speed)

1 - normal

2 - subtle (mild/questionable)

3 - oobvious (striking/clear)

Grading of Scapular Dyskinesis

no difference

Is there a difference in the presence of shoulder symptoms between normal and obvious dyskinesis subjects?

false

T or F: scapular dyskinesis is influenced by the presence of shoulder pain

decreased symptoms with retracted scapula

What does a positive scapular retraction test mean?

decreased symptoms with manual scapular resistance

What does a positive scapular assistance test mean?

dual leg stance on mound with weight transfer to single leg stance

Throwing Motion: Wind Up

90

During the wind up phase, the trunk and torso rotate ___ degrees

- concentric elevation of stride leg

- isometric contraction of hip abductors + knee extensors of stance leg

Actions During the Wind Up Phase

less

______ fource is generated during wind up as compared to other stages

begins with linear velocity of stride leg towards target, and push off of stance leg

Throwing Motion: Stride

coil/uncoil of LEs begins to transition through torso; preparation of throw in UE

Motions Occuring in LE/UE's During Stride

stride

Stride phase concludes when _____ leg contacts the ground

Throwing Motion: Arm Cocking

throwing motion:

begins when stride leg contacts the ground

increased BOS transitions force through uncoil of trunk

How does BOS change in the arm cocking phase of throwing?

increase in PE of throwing arm via proximal segments

How does PE change in the arm cocking phase of throwing?

large rotational force and torque met by dynamic stability of GH stabilizers

Motions/Force Occuring During Arm Cocking

eccentric contraction through greater ranges of ER

What is the role of the subscapularis, latissimus dorsi, and pec muscles during the arm cocking phase of throwing?

external rotation

Arm cocking phase concludes when throwing arm achieves maximal ______ ______

begins with maximal GH ER

Throwing Motion: Acceleration

concentric contraction

What is the role of the triceps, pectoralis major, latissimus dorsi, and serratus during the acceleration phase of throwing?

develop larger magnitude of velocity; dependent on concentric load

How does the lag to the internal rotators of the GH during the acceleration phase of throwing assist velocity?

ball; hand

Acceleration phase concludes once the _____ has left the player's _____

begins at ball release

Throwing Motion: Deceleration

large eccentric load demand to slow down arm

What is the role of the infraspinatus and teres minor during the deceleration phase of throwing?

large

______ force is required to decelerate the UE

internal rotation

Deceleration phase concludes at maximal shoulder _______ _______

due to large eccentric load

Why is the deceleration phase a common point of injury for baseball players?

begins at maximal IR

Throwing Motion: Follow Through

stride leg

Which leg absorbs the force of the pitch in the follow-through phase of throwing?

continued deceleration eccentrically

What is the role of the deltoid and rotator cuff muscles in the follow-through phase of throwing?

deceleration

Follow Through phase concludes with full ________ of the body in motion

during the deceleration or follow-through phases

When do most throwing overuse injuries occur?

humeral retroversion and increased load on UCL

What can adaptive changes to tissue in the dominant throwing arm cause?

GIRD, internal impingement, SLAP tears, RTC tears

What injuries are adaptive changes from throwing associated with?