The Throwing Athlete

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The Throwing AthleteMichael RosenblatPT, CEP, NCCP(Triathlon), Dip(FLM), BASc(KIN), MSc(PT)

ContentsBiomechanics of ThrowingAcquired and Adaptive ChangesExaminationRehabilitation

Wind-up Phase

ObjectiveTo position the body in the most advantageous way possible to deliver the pitch

BiomechanicsThe phase begins with dual legs stanceWeight is transferred onto the back legTorso must rotate 90 degrees

PathomechanicsWeak hip abductors and knee extensors on the stance leg create an unstable baseThis causes distal components of the kinetic chain to compensate to maintain velocity

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

3

Stride PhaseObjectiveTo create linear velocity through forward motion

BiomechanicsThe stride phase concludes when the lead foot of the stride leg contacts the ground

PathomechanicsLack of stance leg hip internal rotation leads to premature opening up of the pelvis, affecting distal aspects of the kinetic chainLeads to upper extremity injuries

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

4

Arm Cocking Phase

ObjectiveTo position the body in the most advantageous way possible to deliver the pitch

BiomechanicsThe phase begins with dual legs stanceWeight is transferred onto the back legTorso must rotate 90 degrees

PathomechanicsWeakness in stride leg quadriceps can cause poor force generation, creating instabilityCauses overuse injuries of the shoulder and elbowPitching motion with early trunk rotation, increased maximal external rotation, and decreased elbow flexion lead to increase valgus torque on the elbow

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

Valgus StressTensile forces on medial elbowUlnar ligament stressCompressive force on radiocaptialler jointOsteochondral damageShear forceChondramalacia, osteophyte formation 5

Arm Acceleration Phase

BiomechanicsBegins with GH joint in MER and ends with ball release from throwers handPosition of shoulder and elbow during acceleration and ball release are important for velocity90 degrees of horizontal abduction (coronal abduction) can optimize strength and minimize shoulder impingement

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

Arm Deceleration Phase

BiomechanicsBegins with ball release and concludes when the shoulder reaches maximum internal rotationLarge 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)

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

Follow-Through Phase

BiomechanicsThe throwers body weight and momentum of ball release result in weight transfer to the stride legThe stride leg stabilizes and absorbs the body force of the pitchMost overuse injuries to the posterior arm or trunk occur during the deceleration or follow-through phase Weber A et al. Sports Med Arthrosc Rev 2014;22:72-79.

Baseball Nodes and ConsequencesNodeNormal MechanicsPathomechanicsResultTo be EvaluatedFoot positionDirectly toward home plateOpen or closedIncreased load on trunk or shoulderHip and/or trunk flexibility and strengthKnee motionStand tallIncreased knee flexionDecreased force to armHip and knee strengthHip motionFacing home plateRotation away from home plateIncreased load on shoulder and elbowHip and trunk strengthTrunk motionControlled lordosisHyperlordosis and back extensionIncreased load on abdominals and slow armHip and trunk strengthScapular positionRetractionScapular dyskinesisIncreased internal and external impingement with increased load on rotator cuff musclesScapular strength and mobilityShoulder/scapular motionScapulohumeral rhythm with arm motion (scapular retraction/humeral horizontal abduction/humeral external rotation)Hyper angulation of humerus in relation to glenoidIncrease load on anterior shoulder with potential internal impingementScapular and shoulder flexibility and strengthElbow positionHigh elbow (above 90 abduction)Dropped elbow (below 90 abduction)Increased valgus loads on elbowScapular position and strength, trunk and hip flexibility and strengthHand positionOn top of ballUnder or side of ballIncreased valgus load on elbowShoulder and elbow position

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

Acquired and Adaptive ChangesRange of motionIncrease 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

BonyIncrease in humeral retroversion (HR)Correlated with GIRDGlenoid also undergoes adaptive retroversionAllows an increase in ER of the humerus before physiological limit

ScapularDecreased upward rotation leads to increase injury ratesCapsular tightness can lead to increase protractionCauses decrease strength and decreased sub-acromial spaceTokish J et al. Sports Med Arthrosc Rev 2014;22:88-93

ExaminationObservationBilateral evaluation for shoulder girdle musculature atrophy, scapular resting position, evidence of prior injury

Range of motionDecreased ROM in the hip and trunkCompare hip internal and external rotationTotal arc of motion (TAM)Abnormal scapulohumeral rhythmEarly protraction and abduction (GIRD)

StabilityAC and SC jointsStrengthHip and trunk1-leg stability seriesStanding balance testSingle leg squatRotator cuff musculatureExternal rotators should be at 80% of internal rotators

Special testsScapular assistance test (SAT)Can evaluate scapular contribution to impingementScapular retraction test (SRT)Evaluates scapular contribution to supraspinatus weakness

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

Standing Balance TestIn the standing balance test, the patient is asked to place their hands over their chest and stand on 1 leg with no other verbal cue. Deviations such as a Trendelenburg posture or internally or externally rotating the weight-bearing limb indicate inability to control the posture and have been found to correlate with proximal core weakness especially in the gluteus medius

Single Leg SquatThe single-leg squat is the next progressive evaluation. Assuming the same starting point as the standing balance test, the patient is asked to do repet- itive partial half squats going down and returning to the standing position with no other verbal cues. Similar devi- ations in the quality of the movement are assessed as in the standing balance test. A Trendelenburg posture that may not be noted on standing balance may be brought out with a single-leg squat. The patient may also use their arms for balance or may go into an exaggerated flexed or rotated posturecorkscrewingto put the gluteal or short rotator muscles on greater tension to compensate for muscular weakness. Increase LUMBAR LORDOSIS or THORACIC KYPHOSIS can indicate decrease core stability

11

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 TestThe 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 ChainExamination EmphasisNormalAbnormalResultEvaluationOne 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 limitsSide-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

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

Examination: Proximal to D