the throwing athlete

The Throwing Athlete

Michael RosenblatPT, CEP, NCCP(Triathlon), Dip(FLM), BASc(KIN), MSc(PT)

Contents

• Biomechanics of Throwing• Acquired and Adaptive Changes• Examination• Rehabilitation

Wind-up PhaseObjective• To position the body in the most

advantageous way possible to deliver the pitch

Biomechanics• The phase begins with dual legs stance• Weight is transferred onto the back

leg• Torso must rotate 90 degrees

Pathomechanics• Weak hip abductors and knee

extensors on the stance leg create an unstable base

• This causes distal components of the kinetic chain to compensate to maintain velocity

Weber A et al. Sports Med Arthrosc Rev 2014;22:72-79.

Stride PhaseObjective• To create linear velocity through

forward motion

Biomechanics• The stride phase concludes when

the lead foot of the stride leg contacts the ground

Pathomechanics• Lack of stance leg hip internal

rotation leads to premature “opening up” of the pelvis, affecting distal aspects of the kinetic chain

• Leads to upper extremity injuries


Arm Cocking PhaseObjective• To position the body in the most

advantageous way possible to deliver the pitch

Biomechanics• The phase begins with dual legs stance• Weight is transferred onto the back leg• Torso must rotate 90 degrees

Pathomechanics• Weakness in stride leg quadriceps can cause

poor force generation, creating instability• Causes overuse injuries of the shoulder and

elbow• Pitching motion with early trunk rotation,

increased maximal external rotation, and decreased elbow flexion lead to increase valgus torque on the elbow


Arm Acceleration Phase

Biomechanics• Begins with GH joint in MER and ends with ball release from thrower’s hand• Position of shoulder and elbow during acceleration and ball release are

important for velocity• 90 degrees of horizontal abduction (coronal abduction) can optimize strength

and minimize shoulder impingement


Arm Deceleration Phase

Biomechanics• Begins with ball release and concludes

when the shoulder reaches maximum internal rotation• Large eccentric loads are necessary to

decelerate the throwing arm

• The large internal rotation torque placed on the GH joint is counterbalanced by contraction of the rotator cuff external rotators (infraspinatus and teres minor)


Follow-Through Phase

Biomechanics• The thrower’s body weight and

momentum of ball release result in weight transfer to the stride leg

• The stride leg stabilizes and absorbs the body force of the pitch

• Most overuse injuries to the posterior arm or trunk occur during the deceleration or follow-through phase


Baseball Nodes and ConsequencesNode Normal Mechanics Pathomechanics Result To be Evaluated

Foot position Directly toward home plate Open or closed Increased load on trunk or shoulder

Hip and/or trunk flexibility and strength

Knee motion Stand tall Increased knee flexion Decreased force to arm Hip and knee strength

Hip motion Facing home plate Rotation away from home plate

Increased load on shoulder and elbow

Hip and trunk strength

Trunk motion Controlled lordosis Hyperlordosis and back extension

Increased load on abdominals and “slow arm”

Hip and trunk strength

Scapular position Retraction Scapular dyskinesis Increased internal and external impingement with increased load on rotator cuff muscles

Scapular strength and mobility

Shoulder/scapular motion Scapulohumeral rhythm with arm motion (scapular retraction/humeral horizontal abduction/humeral external rotation)

Hyper angulation of humerus in relation to glenoid

Increase load on anterior shoulder with potential internal impingement

Scapular and shoulder flexibility and strength

Elbow position High elbow (above 90° abduction)

Dropped elbow (below 90 abduction)

Increased valgus loads on elbow

Scapular position and strength, trunk and hip flexibility and strength

Hand position On top of ball Under or side of ball Increased valgus load on elbow

Shoulder and elbow position

Kibler W et al. Clin Sports Med 2013;32:637-651

Acquired and Adaptive ChangesRange of motion• Increase in glenohumeral external rotation (10 to 15 degrees)• Decrease in GH internal rotation (10-15 degrees)• GIRD (glenohumeral internal rotation deficit)

– Loss of IR of affected arm (> 25 degrees)– Total arc of motion (TAM) deficit

Bony• Increase in humeral retroversion (HR)

– Correlated with GIRD• Glenoid also undergoes adaptive retroversion

– Allows an increase in ER of the humerus before physiological limit

Scapular• Decreased upward rotation leads to increase injury rates• Capsular tightness can lead to increase protraction

– Causes decrease strength and decreased sub-acromial space

Tokish J et al. Sports Med Arthrosc Rev 2014;22:88-93

ExaminationObservation• Bilateral evaluation for shoulder girdle

musculature atrophy, scapular resting position, evidence of prior injury

Range of motion• Decreased ROM in the hip and trunk

– Compare hip internal and external rotation

• Total arc of motion (TAM)• Abnormal scapulohumeral rhythm

– Early protraction and abduction (GIRD)

Stability• AC and SC joints

Strength• Hip and trunk

– 1-leg stability series• Standing balance test• Single leg squat

• Rotator cuff musculature– External rotators should be at 80% of

internal rotators

Special tests• Scapular assistance test (SAT)

– Can evaluate scapular contribution to impingement

• Scapular retraction test (SRT)– Evaluates scapular contribution to

supraspinatus weakness

Provencher M et al. Sports Med Arthrosc Rev 2014;22:80-87.

Examination: Scapular Assistance Test

The SAT can be used to evaluate scapular contributions to impingement and rotator cuff strength by assessing muscle weakness. To perform the test, the practitioner applies gentle pressure on the inferior medial scapular angle as the patient elevates the arm. This assists the serratus anterior and lower trapezius muscles in upward rotation and posterior tilt of the scapula causing reduced subacromial impingement and optimizing the length of the rotator cuff muscles. A positive result is when the patient notes increased arc of motion without pain or impingement symptoms.

Provencher C et al. Sports Med Arthrosc Rev 2014;22:80-87

Examination: Scapular Retraction Test

The SRT is used to evaluate scapular protraction contribution to supraspinatus muscle weakness. Strength of supraspinatus is initially assessed with the arm in the “empty can” position. The scapula is then manually stabilized in a retracted position and strength testing is per- formed again. A positive test is when there is an increase in strength (although not a decrease in pain) with the scapula stabilized

Provencher C et al. Sports Med Arthrosc Rev 2014;22:80-87

Examination: Proximal to Distal Kinetic Chain

Examination Emphasis Normal Abnormal Result Evaluation

One leg stability: stance Negative Trendelenburg Positive Trendelenburg Decrease force to shoulder Decrease force to shoulder

One leg stability: squat Control of knee varus/valgus during decent

Knee valgus or corkscrewing during decent

Alters arm position during task

Dynamic postural control

Hip rotation Bilateral symmetry within known normal limits

Side-to-side asymmetry and/or not within normal limits

Decrease trunk flexibility and rotation

Internal and external rotation of hip

Plank Ability to maintain body position for at least 30 s

Inability to maintain body position

Decreased core stability and strength

Dynamic postural control in suspended horizontal position

Scapular dyskinesis Bilateral symmetry with no inferior angle or medial border prominence

Side-to-side asymmetry or bilateral prominence of inferior angle and/or medial border

Decreased rotator cuff function and increased risk of internal and/or external impingement

Scapular muscle control of scapular position (“yes/no” clinical evaluation manual corrective maneuvers)

Shoulder rotation Side-to-side symmetry or internal and external rotation values less than 15 or less than 5

Side-to-side asymmetry of 15 or more in internal and/or external rotation or 5 or more of total range of motion

Altered kinematics and increased load on the glenoid labrum

Internal and external rotation of glenohumeral joint


Examination: Proximal to Distal Kinetic Chain

Examination Emphasis Normal Abnormal Result Evaluation

Shoulder muscle flexibility Normal mobility of pectoralis minor and latissimus dorsi

Tight pectoralis minor and/or latissimus dorsi

Scapular protraction Palpation of pectoralis minor and latissimus dorsi

Shoulder strength Normal resistance to testing in anterior and posterior muscles

Weakness and/or imbalance of anterior and posterior muscles

Scapular protraction, decreased arm elevation, strength, and concavity- compression

Muscle strength from a stabilized scapula

Joint internal derangement All provocative and stress testing negative

Pop, click, slide, pain, stiffness, possible “dead arm”

Loss of concavity-compression and functional stability

Labral injury, rotator cuff injury or weakness, glenohumeral instability, biceps tendinopathy


Rehabilitation: Scapular Dyskinesis

1. Begin with ROM exercises of the hip and spine2. Stretching – Trapezius, pectoralis minor, levator scapula, teres

minor, infraspinatus, latissimus dorsi3. Scapular protraction and retraction exercises4. Strength protocol

a. Closed kinetic chain exercises first(focus on serratus anterior and trapezius)b. Advanced Throwers Ten

Rehabilitation:Early Isometric Scapular Exercises

Inferior Glide

Low Row

Kibler W et al. Am J Sports Med 2008;36(9):1789-1798

Rehabilitation:Early Dynamic Scapular Exercise

Robbery


Lawnmower

Rehabilitation:Average Amplitude EMG Activity

Inferior Glide Low Row Lawnmower Robbery

Upper Trapezius

8.1 (5.9) 10.4 (8.1) 21.8 (15.7) 31.6 (16.7)

Lower Trapezius

19.4 (26.6) 15.4 (11.6) 30.5 (19.2) 27.0 (20.8)

Serratus Anterior

23.4 (19.6) 28.2 (20.8) 25.5 (21.4) 20.9 (16.8)

Anterior Deltoid

4.6 (2.4) 16.6 (13.3) 5.5 (3.6) 7.4 (5.5)

Posterior Deltoid

8.6 (6.0) 42.4 (23.2) 16.2 (10.6) 14.0 (9.2)


References1. Kibler W et al. Electromyographic analysis of specific exercises for scapular control in early

phases of shoulder rehabilitation. Am J Sports Med 2008;36(9):1789-1798

2. Kibler W et al. Pathomechanics of the throwing shoulder. Sports Med Arthrosc Rev 2012;20:22-29.

3. Kibler W et al. Mechanics and pathomechanics in the overhead athlete. Clin Sports Med 2013;32:637-651

4. Provencher M et al. The role of the scapula in throwing disorders. Sports Med Arthrosc Rev 2014;22:80-87.

5. Tokish J et al. Acquired and adaptive changes in the throwing athlete: implications on the disabled throwing shoulder. Sports Med Arthrosc Rev 2014;22:88-93.

6. Weber A et al. The biomechanics of throwing: simplified and cogent. Sports Med Arthrosc Rev 2014;22:72-79.

the throwing athlete

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