Biomechanics of Throwing

this is the topic of sports biomechanics and made for MPT sports students

1. Biomechanics of throwing Dr Nishank Verma mpt (sports), PhD Jamia Millia Islamia

2. Introduction The action of propelling an object or ball using a throw which involves linked motion of the whole body. Throwing is a total body activity.It is a elaborate,synchronous progression of body movement that starts in the legs and trunk and proceeds to the upper extremity and produce ballistic motion of the upper extremity & concludes to the rapid propulsion of ball. Sports involving throwing motion- baseball,american football,tennis,racket,javelin throwing,hand ball throwing,cricket,swimming and volleyball. Types of throwing movements- Underarm throwing Sidearm throwing Overarm throwing

3. Patterns for throwing

4. Phases of throwing

5. Phase of throwing 1. Windup : begins with maximum foot lift and ends with hand separation. 2. Stride : front foot moves downwards. 3. Arm cocking : pelvis and upper trunk rotation and maximal ER occurs. 4. Arm acceleration : from maximum ER to ball release. 5. Arm deceleration : from ball release to end range IR 6. Follow through : from maximal IR until pitcher regains balanced position.

6. Duration of throwing phases 6 phases takes less then 2 seconds to occur. First 3 phases -wind up,early cocking and late cocking takes approximately 1.5 sec in total. 4rth phase -acceleration- 0.05 seconds Greatest angular velocities and largest rotation occurs during this phase. Final two phases -last approximately- 0.35 sec.

7. Wind up phase Windup phase -puts the thrower in good starting position. Starts with starts of motion & ends with maximum knee lift of the stride leg. Duration -0.5-1.0s

8. kinematics lead leg is lifted by concentric contraction of hip flexors(rectus femoris,iliopsoas & sartorius ). Lead leg faces the target. Stance leg bend slightly,controlled by eccentric contractions from the quadriceps muscle & remain in a fairly fixed position due to isometric contraction of the quadriceps until a balanced position is achieved. Hip abductor(gluteus medius,minimus & TFL) of stance leg also contract isometrically to prevent downward tilting of opposite side of the pelvis. Hip extensors of the stance contract both eccentrically & isometrically to stabilize hip flexion. Shoulder -partially flexed & abducted(held in this position by anterior and middle deltoids,supraspinatus & clavicular portion of pectoralis major. Elbow -flexion(45deg) is maintained by isometric contraction of elbow flexors( biceps,brachialis and brachioradialis ).

9. Stride phase Begins at the end of the windup phase,when the lead leg begins to fall & move towards the target & two arm separates from each other. Thrower turns the lead side target. This phase ends when the lead foot first contacts the ground. Duration -0.50-0.75s Ending of the phase ends when lead foot contacts the ground.

10. kinematics Hip -Eccentric contraction of the hip flexors of the lead leg,concentric contraction from the stance leg hip abductor helps to lengthen the stride. As the lead leg falls downward and forward the lead hip begins to rotates externally( g.max,sartorius and other 6 deep external rotators) and stance hip extends due to concentric contraction of the hip extensors(G.max and hamstrings). Trunk tilted sideways away from the target. Stride length depends on the type of throw. Pitching-70-80% of the atheletes height. Position of the lead knee is flexed approximately 45-55 degrees at foot contact Lead foot -should placed directly in front of the rear foot towards the direction of throw. Elastic energy generated in the legs,trunk & arm during the sride phase is transferred to the subsequent phases of throw.

11. Shoulde r-both shoulder abduct,externally rotates & horizontally abduct owing to concentric muscle action. At lead foot foot contact-shoulder abduction-80-100 degrees(deltoid & supraspinatus are responsible for abduction.Upper trapezius and serratus anterior upwardly rotate & position the glenoid for the humeral head. Throwing arm is positioned slightly behind the trunk( horizontly abducted) & in football throwing slightly anterior. At shoulder posterior deltoid,lattismus dorsi,infraspinatus & teres minor works to bring the arm posteriorly and in externally rotated position. Rhomboids & middle trapezius retracts the scapula. Elbow -approximately-80-100 degrees. Forearm rotated up,approching vertical position. Finger extension and wrist flexion.

12. Arm-cocking phase Begins at lead foot contact and ends at maximum shoulder external rotation. Duration-0.10-0.15sec

13. kinematics Upper body is rotated to face the target Quadriceps of the lead leg initially contracts eccentrically to decelerates knee flexion and then concentrically and isometrically to stablilize the lead leg during the cocking phase. Throwers body is fully stretched out in the direction of the target. Ankle of the stance leg planter flexed & leaves the contact this motion occurs concurrent with pelvic rotation,just after foot contact. Pelvis continues transverse motion,hip internally rotates,occurs approximately 0.03-0.05 sec after baseball pitching-max rotation-700deg/sec. Trunk muscles are on stretch-recoil & the subsequent shoulder rotation. Upper trunk rotates in reverse direction to the rotation of the pelvis. Upper torso angular velocity is maximum during this phase-900-1300deg/sec is achieved. Abdominals & oblique muscles is placed on stretch during trunk hyperextension. Trunk rotates to face the target,throwing shoulder horizontally adducts,moving from position of 20-30degrees of horizontal abduction at the lead foot contact to a position of 15-20 degrees of horizontal adduction at the time of maximum shoulder external rotation.

14. Shoulder- This leads to maximum shoulder horizontal adduction velocity relative to the trunk is approximately-500-600 degrees/sec. Pectoralis major anterior deltoids(horizontal adductors initially contracts eccentrically then isometrically to stabilize to allow the arm to move with the trunk,cocentrically to provide dynamic horizontal adduction at the shoulder. Shoulder girdle muscles( levator scapulae,s.anterior,trapezius,rhomboids & p.minor ) work. Serratus anterior is more active to provide both stabilisation & protraction to the scapula. All muscles stabilize the scapula & provides position of the glenoid for the subsequent action of the humeral head. Throughout arm cocking phase shoulder remains abducted approx 80-100degrees. External rotation-165-180degrees(inc. stretch on anterior capsule).

15. Elbow -90 degrees about 30ms before maximum shoulder external rotation.triceps contract eccentrically then isometrically in resisting centripital elbow flexion then triceps contract concentrically to aid in elbow extension. Pitcher arm legs behind as the trunk rapidly rotates forward to phase the hitter,generating a peak angular velocity of around 6000deg/ sec,occuring 0.03 to 0.05 sec after lead foot contact,followed by peak torso angular velocity of nearly 1200 deg/ sec,occuring 0.05 to 0.07 sec after lead foot contact.

16. Arm acceleration phase Trunk flexes forward to neutral position from extended position. Begins with maximal shoulder external rotation and ends at ball release. This phase is very rapid phase. Shoulder abduction is 90 degrees during this phase. Duration -This phase lasts 0.03 to 0.05 sec.

17. kinematics Elbow extension begins prior to internal rotation allows throwers to reduce rotational inertia about the arm longitudinal axis & therefore allowing greater internal rotational velocity of approximately 7000-8000 deg/sec in pitching. Subscapularis is most active followed by lattismus dorsi & pectoralis major. Trunk flex forward from a vertical position approx-25-40 degrees. Throwing shoulder remains abducted approx 80-100 degrees throughout acceleration phase which implies strong position for the shoulder. Shoulder movement remains same but trunk position changes with the throwing type.(overhead-trunk sideways,sidearm -trunk vertical) Rotator cuff and scapular muscles demonstrate high activity to control humeral head & scapular stabilization. Elbow extension due to centrifugal force at elbow as trunk & arm rotates-2100deg/sec

18. Increase triceps and anconeous activity also acts as arm stabilizer. Elbow angular velocity is due to rotatory action of other parts of the body such as hips,trunk & shoulder. Ball release -elbow is fully extended & slightly anterior at release elbow flexed to 20-30 degrees & horizontal adduction5-20 degrees.( inc.varus force can cause wedging of olecranon fossa . Elbow extension -from 80degrees to 20 degrees due to centrifugal force. Increase activity of elbow flexors-adds compressive force ans stability & control rate of elbow extension. Hand moves from hyperextended wrist position at maximum shoulder external rotation to a neutral wrist position at ball release.wrist flexors active during throwing activity initiates eccentric then concentric contraction,pronator teres is also active. Internal rotators contract concentrically to generate peak internal rotation angular velocity of approx.6500 deg/sec near ball release,

19. Arm deceleration phase Duration -0.03 to 0.05 sec. From ball release to maximum internal rotation trunk continues to flexion.

20. kinematics Lead knee and throwing elbow extends. Pronation due to activation of pronator teres . Upward reaction of the flexing trunk & hip. Large eccentric load at elbow & shoulder to decelerate the arm. Biceps and supinator also eccentrically loaded. Elbow extension terminates at 15-25degrees(triceps active) Posterior shoulder muscles stop the shoulder distraction( infraspinatus,lattismus dorsi and posterior deltoid) Lower trapezius,Serratus anterior & rhomboids are quite active providing posterior motion. Rotator cuff muscle limits anterior translation,adduction and shoulder internal rotation. Wrist and finger flexors have very high eccentric activity. Shoulder and elbow torque is more during slider.(>15-20% compressive force) Maximum shoulder adduction torque of approximately 80-110 Nm are produced to resist shoulder abduction & superior humeral head translation.

21. Follow through phase Begins at the time of maximum shoulder internal rotation and ends when completes its movement across the body & position is obtained Last less than 1 sec.

22. kinematics maximum shoulder internal rotation and ends when arm completes its movement across the body and atheletes in in balanced position. Forearm rotated in pronation .

23. Kinetic chain

24. Kinetic chain in overhead pitching Consists of linked motion of hips & trunk and culminates with a ballistic motion of the upper extremity to propel the ball. All phases are intricately coupled,resulting in efficient generation & transfer of energy from body into arm & ultimately,the hand & ball. The legs & trunk serves as the main force generators of the kinetic chain,scapula is in facilitating this energy transfer distally to the hand. Kibler & chandler-20% decrease in kinetic energy delivered from hip & trunk to the arm requires a 34% increase in the rotational velocity of the shoulder to impart the same amount of force to the hand. Improvement in velocity also reduces kinetic contributions of the shoulder to produce top velocity. Time between front foot contact and ball release-0.145sec.

25. Wind up -wind up & stride position the body to optimally generate the forces & power required to achieve top velocity. The pitcher keeps his center of gravity over his back leg to allow generation of maximum momentum once forward motion is initiated. If the pitchers body and momentum falls prematurely,the kinetic chain will be distrupted & greater shoulder force will be required to propel the ball at top velocity. Early cocking/stride -the stride functions to increase the distance over which linear and angular trunk motion occurs,allowing for increased energy production for transfer to the upper extremity. The stance knee & hip extend & lead to the initiation of pelvic rotation & forward tilt,followed by upper torso rotation.Pelvis achieves maximum rotational velocities of 400 to 700 degrees per second during this phase. The lead foot should land in line with stance foot,pointing towards home plate or in a few degrees of internal rotation. If the foot lands too closed (stride foot in front of stance foot),pelvis rotation may be limited causing pitcher to throw across the body.

26. Late cocking -pelvis reaches its maximum rotation & the upper torso continues to rotate & tilt forward and forward and laterally. Maximum shoulder internal rotation torque occurs just before maximum shoulder external rotation. Near the end of arm cocking(64% of time from foot contact until ball release),maximum valgus torque is experienced at elbow. Flexors and pronator muscles generates a counter varus torque(64 Nm).adaptive increase in elevation and upward rotation scapula is important,ensuring sufficient subacromial space to accommodate the 80-100 of humeral abduction in throwing position without impingement. The rotator cuff muscles provide a compressive force of 550 to 770N to resist shoulder distraction caused by the torque of the rapidly rotating upper torso. The biceps muscle reaches peak activity as it flexes the elbow,limits anterior translation and provides a compressive force on the humeral head. As the shoulder approaches maximum external rotation,the subscapularis,pectoralis major and lattissmus dorsi are eccentrically contracting applying a stabilizing anterior force to the anterior force to the glenohumeral joint,and halting external rotation. Increased amount of shoulder external rotation help to allow the accelerating forces to act over the longest distance,allowing greater prestretch & elastic energy transfer to the ball during accleration .

27. Acceleration phase -the trunk continues to rotate & tilt,initiating the transfer of potential energy through upper extremity. The scapula protracts to maintain a stable base as the humerus undergoes horizontal adduction and violent internal rotation. This rapid motion delivers the arm from as much as 175 degrees of external rotation to 100 deg of internal rotation(at ball release) in only 42-58 milliseconds. A decreased time to maximum shoulder internal rotation & increased trunk tilt at ball release have been associated with an increase in ball velocity. Internal rotation velocities as high as 7000 to 9000 degrees per second have been reported. Elbow extension results from a combination of the centrifugal force generated by a rotating torso and concentric contraction of the triceps; immediately followed by shoulder internal rotation. The biceps brachii supplies elbow flexion torque,reaching a maximum value of 61Nm just before the ball release

28. Maximum elbow extension angular velocity occurs just before ball release & may reach mean angular velocity of 2251 degrees per second.Ball release is aided by wrist flexion to neutral in the 20 ms proceeding release and radioulnar pronation to 90 degrees in 10ms prior to release. Concentric rectus femoris contraction contributes to lead leg hip flexion & knee extension,providing a stable front side help to create increased angular momentum of the trunk. Increased forward trunk tilt allows the pitching extremity to accelerates through a greater distance allowing more force to be trnsferred to the ball. Maximal angular velocity 300-450degrees per second at ball release.

29. Deceleration -this is the most violent phase of throwing cycle,resulting in the greatest amount of joint loading encountered during throwing. Excessive posterior(400N) and inferior shear forces(300 N) occur,as do elevate compressive forces(>1000 N) & adduction torques. The massive eccentric contractile requirements of the posterior shoulder capsular & soft tissues reactions commonly seen in throwers & for glenohumeral interenal rotation deficit seen inj pitchers. Follow through -culminates with the pitcher in fielding position. The decrease joint loading and minimal forces during this phase render it an unlikely culprit for injury.

30. kinetics The leg and trunk serves as the main force generators of kinetic chain. Scapula is the key transferring energy distally to the hand . So,any scapular dysfunction prohibits optimum energy transfer. 20% decrease in kinetic energy delivered from hip and trunk to the arm requires 34% inc. in rotational velocity of the shoulder to impart the same amount of force to hand. Transfer of power from the point of plant foot to the tip of throwing hand is the process that relies on strength,flexibility and ROM of the foot,ankle,knee,thigh,hip,core,chest,shoulder,elbow,forearm and hand.problem in any part can lead to problem in energy transfer.

31. Kinetics of scapular position Provides stable platform for the humeral head during rotation and elevation,while transferring kinetic energy from the lower extremity and trunk to lower extremity. Kibler found that only half of the kinetic energy generated by lower limb and trunk rotation & is transferred to the upper limb through the scapulothoracic joint which is a part of kinetic chain. Throwers develops chronic adaptations for more efficient performance of the throwing motion. Throwing atheletes have increased upward rotation,internal rotation and retraction.Loss of upward rotation in throwing injury leads to associated with impingement of subacromial structures. Fatigue also adversely affects scapular movement which leads to decrease external rotation and posterior rotation and posterior tipping and upward rotation of the scapula.( dec.approximately in 5 innings). Internal rotation increases with scapular elevations. Increase in retraction may facilitates a maximum cocking position for subsequent explosive acceleration during the throwing motion.

32. Elite pitchers can generate ball velocity that exceeds 144.8km/hr in order to create this velocity,the shoulder rotates at an angular velocity of upto 7000deg/sec. At ball release distractive forces at the shoulder 950N. At deceleration phase-compressive forces created by rotator cuff muscles & deltoid are in the range of 1090N and posterior shear forces of upto 400N. If compressive force do not counteract high distractive force,injuries wiil occur.

33. Increased pitching velocity and accuracy depends on Lead knee flexion Forward trunk tilt Peak elbow external rotation Maximum pelvic angular velocity. Synchronicity and coordination between upper and lower extremity. Body height and weight. Bone length. Specific arm position timing of ball release.

34. ELECTROMYOGRAPIC CHANGES DURING THROWING

35. Wind up Lead knee lifted controlled by concentric of hip flexors and stance leg bend controlled by eccentic contraction of quadriceps and remain in fixed postion by contraction of quadriceps. Hip abductors of stance leg contract isometrically to prevent downward tilting of opposite side pelvic. Hip extensors contract both eccentrically and isometrically to stabilize hip flexors. Shoulder activity during the wind up is generally very low due to the low movements. .

36. The greatest activity is from upper trapezius , serratus anterior and anterior deltoids. All contract concentrically to upwardly rotate and elevate the scapula and abduct the shoulder as the arm is initially brought overhead, and then contract eccentrically to control downward scapular rotational and shoulder adduction as the hands are lowered to approximately chest level. The muscles of the rotator cuff, which has dual function as glenohumeral joint compressors and rotators, have their lowest activity during this phase.

37. Low shoulder activity given that shoulder forces and torques generated during this phase are low. Elbow in flexed and is maintained by isometric contraction of elbow flexors.

38. Stride phase Hip flexors eccentrically contract control leg lowering. Concentric contraction of stance leg hip abductors lengthen the stride. Forward movement is initiated by some degree by hip abductors followed by knee and hip extensors from stance leg. As the lead legs falls downward the lead hip externally rotate and stance hip internally rotate. Stance hip also extend due to concentric contraction from hip extensors. Through out this phase trunk is tilted slightly sideways away from target. Stride length is approximately 70 to 80% of athletes height. Lead foot should be slightly flexed and point inward.

39. The scapula upwardly rotates, elevates and retracts. Shoulder abduct, externally rotate and horizontally abduct due to concentric activity of deltoid, supraspinatus , infraspinatus , serratus anterior and upper trapezius . More muscles are activated and to a higher degree during the stride compared with wind up. The supraspinatus has its highest activity during this phase as it works not only to abduct the shoulder but also to help compress and stabilize the glenohumeral joint. The deltoid also exhibit high activity to initiate and maintain the shoulder in abducted position.

40. Throwing arm position should be slightly behind the trunk. Posterior deltoid, latissmus dorsi , teres major and posterior rotator cuff muscles are responsible for horizontally abducting the shoulder while romboidus and middle trapezius retract the scapula. Elbow flexors muscles of throwing arm contract eccentrically and isometrically in controlling elbow flexion. Wrist and fingers extensors have very high activity as wrist has to move from a position of slight flexion to position of hyperextension. These muscles work concentrically as they work against gravity as throwing hand facing downward.

41. Arm cocking phase Quadriceps of lead leg initially contract eccentrically to decelerate knee flexion then contract eccentrically to decelerate knee flexion then contract isometrically to stabilize the lead leg. The abdominal and oblique muscles are stretched due hyperextension of lumbar trunk that occurs as the upper torso rotates. During this phase the kinetic energy that is generated from the larger lower extermity and trunk segments is transferred up the body to the smaller upper extremity segments. High to very high shoulder muscle activity is needed during this phase to keep the arm moving with the rotating trunk as well as to control the resulting shoulder external rotation which peaks near180 degrees. Moderate activity is needed by the deltoid to maintain the shoulder at approx 90 deg of abduction throughout the phase.

42. Activity from pectoralis major and anterior deltoid is needed during this phase to horizontally adduct the shoulder to a peak angular velocity of approx 600deg/sec from a position of approx 20 deg of horizontal abduction at lead foot contact to a position of approx 20 deg of horizontal adduction at maximum shoulder external rotation. Large compressive force of approx 80% of body weight is generated by trunk onto upper extremity at the shoulder to resist the large centrifugal force that is generated as arm rotates forward with the trunk. The rotator cuff muscles achieve high to very high activity to resist glenohumeral distraction and enhance glenohumeral stability.

43. The posterior cuff muscles and latissimus dorsi also generate posterior force to humeral head, which help resist anterior humeral head translation and perhaps helps unload the anterior capsule and anterior band of the inferior glenohumeral ligament. Peak shoulder internal rotation torque of 65 to 70 Nm is generated near the time of maximum shoulder external rotation. High to very high activity is generated by shoulder internal rotators which contract eccentically to control rate of shoulder external rotation. Dual function of pectoralis major as it contracts concentrically to horizontally adduct the shoulder and eccentrically to control shoulder external rotation maintain normal length by length tension relationship maintain constant length and in effect contracting isometrically .

44. Same occur with subscapularis as it contracts concentrically to aid in horizontal adduction and eccentrically to help control external rotation and in effect contracting isometrically . Scapular protractors are active especially during this phase to resist scapular retraction by contracting eccentrically and isometrically during early part of phase and contract concentrically during the latter part of this phase to protract the scapula. Serratus anterior generate maximum activity during this phase. Both the triceps brachii (long head) and biceps brachii (both heads) cross the shoulder, they both generate moderate activity during this phase to provide additional stabilization to the shoulder. High eccentric contractions by the triceps brachii are needed to help control the rate of elbow flexion that occurs throughout the initial 80% of this phase.

45. High triceps activity is also needed to initiate and accelerate elbow extension, which occurs during the final 20% of this phase as the shoulder continues externally rotating during this phase. Triceps initially contracts eccentrically to control elbow flexion early in the phase and contracts concentrically to initiate elbow extension later in the phase. The infraspinatus not only helps externally rotate and compress the glenohumeral joint but also helps generate a small posterior force on the humeral head this posterior force on the humeral head helps resist anterior humeral head translation and unloads strain on the anterior capsule during arm cocking.

46. Arm acceleration Like the arm-cocking phase, high to very high activity is generated from the glenohumeral and scapula muscles during this phase in order to accelerate the arm forward. Elbow extension initially begins during the arm-cocking phase. Kinetic energy that is transferred from the lower extremities and trunk to the arm is used to help generate a peak elbow extension angular velocity of approximately 2300 deg/sec during this phase.

47. Moderate activity is generated by the deltoids to help produce a fairly constant shoulder abduction of approximately 90 to 100 degrees, which is maintained regardless of throwing style (e.g., overhand, sidearm). The glenohumeral internal rotators ( subscapularis , pectoralis major, and latissimus dorsi ) have their highest activity during this phase as they contract concentrically to generate a peak internal rotation angular velocity of approximately 6500 deg/sec near ball release.

48. With these rapid arm movements, which are generated to accelerate the arm forward, the scapular muscles also generate high activity, to help maintain proper position of the glenoid relative to the rapidly moving humeral head. Strengthening the scapular musculature is very important. Poor position and movement of the scapula can increase the risk of impingement and other related injuries, as well as reducing the optimal length tension relationship of both scapular and glenohumeral musculature

49. Arm-Deceleration Phase Posterior shoulder musculature, such as the infraspinatus , teres minor and major posterior deltoid and latissimus dorsi , contract eccentrically not only to decelerate horizontal adduction and internal rotation of the UE but also help resist shoulder distraction and anterior subluxation forces. A shoulder compressive force slightly greater than body weight is needed to resist shoulder distraction, and a posterior shear force between 40% and 50% of body weight is generated to resist shoulder anterior subluxation . Scapular muscles also exhibit high activity to control scapular elevation, protraction, and rotation during this phase.

50. High EMG activity from glenohumeral and scapular musculature illustrates the importance of strength and endurance training of the posterior musculature in the overhead-throwing athlete. Weak or fatigued posterior musculature can lead to multiple injuries, such as tensile overload undersurface cuff tears, labral and biceps pathology, capsule injuries, and internal impingement of the infraspinatus and supraspinatus tendons on the posterosuperior glenoid labrum.

51. The biceps brachii generate their highest activity during arm deceleration. The function of this muscle during this phase to twofold. First, it must contract eccentrically along with other elbow flexors to help decelerate the rapid elbow extension that peaks during arm acceleration. This is an important function because weakness or fatigue in the elbow flexors can result in elbow extension being decelerated by impingement of the olecranon in the olecranon fossa, which can lead to bone spurs and subsequent loose bodies within the elbow. Second, the biceps brachii works synergistically with the rotator cuff muscles to resist distraction and anterior subluxation at the glenohumeral joint.

52. Follow through Maximum shoulder internal rotation arm completes its movement across the body and balance position is achieved. A long arc of deceleration from throwing arm as well as sufficient forward tilting of trunk allows energy to be absorbed by large musulature of trunk. Posterior shoulder muscles contract eccentrically to decelerate the arm Serratus anterior highest active of all scapular rotators. Middle trapezius and romboidus eccentrically contract to decelerate shoulder protraction. Wrist and finger extensors moderately active.

53. BIOMECHANICAL IMPLICATIONS

54. Shoulder Injuries in Baseball Primary Rotator Cuff Injuries Compression cuff disease Internal impingement Overuse tendinitis Primary lesions Rotator cuff tears Tensile failure Secondary Rotator Cuff Lesions Anterior instability Compressive cuff disease secondary to laxity Multidirectional instability Posterior instability Primary instability ( nontraumatic ) Tensile failure secondary to laxity

55. Glenoid Labrum Tears Peel-back lesions SLAP lesions Thrower’s exostosis Biceps Tendon Pathology Bicipital tendinitis Ruptures and tears Other Acromioclavicular joint degenerative changes Neurovascular syndromes Scapula disorders Suprascapular nerve entrapment

56. Internal Impingement Internal impingement is one of the most common shoulder lesions seen in baseball pitchers. This lesion occurs when the athlete abducts the arm to 90 to 100 degrees and maximally externally rotates. During this motion, the undersurface of the supraspinatus or infraspinatus tendon (or both) contacts the posterior superior glenoid rim and glenoid labrum. This results in undersurface rotator cuff wear and glenoid labrum fraying and possible detachment. This lesion develops because of the repetitive nature of throwing. Causes may be anterior capsule laxity, posterior capsule tightness,and over-rotation.

57. The diagnosis of internal impingement is established based on subjective history, imaging studies, and physical examination. Internal impingement is most often managed nonoperatively with rest, stretching, and strengthening. Usually, nonoperative treatment is successful in these athletes.

58. ROTATOR CUFF INJURIES The rotator cuff is vital for normal shoulder function, especially in the throwing athlete. High demands placed on the shoulder musculature during throwing can result in subsequent muscle fatigue, eccentric overload, inflammation, and eventual tendon failure. Once the rotator cuff musculature has been injured, the dynamic stabilizing ability iscompromised , and additional injuries such as labrum tears, capsular lesions, and osseous changes can ensue. Poor mechanics often results from this type of chronic inflammation, producing a compensatory mechanism in the throwing act that can contribute to the injury producing scenario. These repetitive muscle strains can result in overuse tendinitis of the rotator cuff.

59. Overuse Tendinitis Overuse tendinitis is commonly seen in the posterior rotator cuff muscles, the infraspinatus , and the teres minor. These occur due to the large stress placed on the shoulder joint during the deceleration phase of throwing. The stresses applied to the posterior rotator cuff musculature effectively exceed the body weight during the deceleration phase. Weakness or fatigue of the external rotators decreases the muscular effi ciency required to decelerate the throwing shoulder properly and can result in tissue damage. A decrease in the power of the infraspinatus and teres minor muscles alters the effectiveness of the subscapular , teres minor, and infraspinatus force couple, and humeral head translation increases . Before musculotendinous infl ammation , the posterior glenohumeral capsule often becomes inflamed, which appears to act as a precursor to posterior rotator cuff tendinitis. This inflamed capsule is referred to as posterior capsulitis .

60. Tensile Lesions A common rotator cuff pathology seen in the thrower is a tensile lesion of the undersurface of the rotator cuff. The mechanism of injury in this instance is deceleration of the arm as the rotator cuff attempts to resist the horizontal adduction, internal rotation, and glenohumeral distraction forces placed on it. Combined, these forces result in an eccentric tensile overload failure and a partial undersurface tear of the rotator cuff caused by repetitive microtrauma . Most commonly, these lesions are found in the region of the supraspinatus tendon . On physical examination, tenderness can be elicited over the supraspinatus or infraspinatus tendon. Obvious gross weakness of the rotator cuff usually is not present, especially in the highly skilled thrower. Palpation of the infraspinatus , teres minor, and posterior capsule can be helpful. Computed tomography (CT) or magnetic resonance imaging (MRI) can reveal a partial undersurface tear of the rotator cuff.

61. Initially, the athlete should begin a rehabilitation program with emphasis on rotator cuff strengthening. If no improvement is made over a period of 3 to 6 months, an arthroscopy may be performed to débride the injured tissue and to attempt to promote a healing response. After this procedure, an aggressive rotator cuff strengthening program must be used to minimize the risk of recurrence and maximize a return to symptom-free function. This program should emphasize eccentric strengthening of the posterior rotator cuff musculature

62. Subacromial Impingement The throwing motion requires the arm to be abducted to 90 degrees while being repetitively submitted to horizontal adduction and internal rotation motions. This motion can produce subacromial impingement symptoms. Often the thrower complains of shoulder pain during activity and especially after prolonged throwing. Once the lesion becomes more severe, pain may be present during all throwing activities. Most athletes respond successfully to a conservative program of active rest, nonsteroidal anti-inflammatory medication, and a progressive rotator cuff strengthening and stretching exercise program. In the thrower, external rotation is often excessive and internal rotation is significantly limited. This limitation of internal rotation results in posterior capsular tightness, which causes the humeral head to migrate anteriorly during overhead motion. Any conservative rehabilitation program should include stretching of the posterior capsule, re-establishing normal internal rotation, and gradual aggressive strengthening of the rotator cuff musculature.

63. Significant weakness of the shoulder’s abductors and external rotators can be seen. Often a repair of the rotator cuff is necessary to allow symptom-free return to normal daily activities. The surgical procedure of choice to repair a rotator cuff tear in a thrower uses an arthroscopic technique that minimizes scarring of the capsule and soft tissue.

64. SHOULDER INSTABILITY The throwing motion requires excessive glenohumeral external rotation, which places extreme tension on the anterior stabilizing structures of the glenohumeral joint and especially the anterior capsule and the rotator cuff musculature. The throwing athlete must exhibit laxity to perform high-performance throwing activities. However, the rotator cuff musculature must control this laxity dynamically for symptom-free throwing. Instability ensues when the dynamic stability is altered and the rotator cuff muscles are unable to control humeral head motion within the glenoid during activities. In the thrower, hyperlaxity is a common problem. The shoulder must be loose enough to allow the tremendous motion necessary to throw a baseball but must be tight enough to provide inherent stability

65. Shoulder instability is restricted by the static stabilizers, the geometry of the joint, and the ligamentous system and labrum. Repetitive overhead throwing often results in stretching of these capsular restraints and can lead to joint capsule injury. As the capsule becomes more lax, the glenohumeral joint depends on an increase in the dynamic muscular effort to provide the required functional stability required. If the dynamic stabilizers fail because of overuse, injury, or pain, underlying primary instability will result. During the cocking and early acceleration phases of throwing, the anterior and inferior portions of the joint capsule are significantly stressed in a repeated fashion. The anteroinferior glenohumeral ligament (anterior band) provides the static stabilization for this anterior force applied with the shoulder abducted to 90 degrees.

66. Shoulder instability is restricted by the static stabilizers, the geometry of the joint, and the ligamentous system and labrum. Repetitive overhead throwing often results in stretching of these capsular restraints and can lead to joint capsule injury. As the capsule becomes more lax, the glenohumeral joint depends on an increase in the dynamic muscular effort to provide the required functional stability required. If the dynamic stabilizers fail because of overuse, injury, or pain, underlying primary instability will result. During the cocking and early acceleration phases of throwing, the anterior and inferior portions of the joint capsule are significantly stressed in a repeated fashion. The anteroinferior glenohumeral ligament (anterior band) provides the static stabilization for this anterior force applied with the shoulder abducted to 90 degrees.

67. The dynamic stability required to supplement the anteroinferior glenohumeral ligament is provided through a rotator cuff muscular contraction on both sides of the glenohumeral joint. In time, the thrower can develop a loose shoulder joint. Because of this ensuing looseness, the thrower must rely on dynamically controlled stability and thus may be predisposed to musculotendinous injuries caused by overuse, such as secondary internal impingement, tensile failure, and rotator cuff failure. The thrower might complain of anterior or posterior shoulder pain, especially during the late cocking and acceleration phases. Also, the thrower might notice clicking, popping, or early arm fatigue with competitive activities. Several clinical tests are routinely performed to determine the degree of anterior humeral head translation on the glenoid . Anterior laxity is determined with the use of a drawer test ( Lachmann’s test of the shoulder) , fulcrum test , or a relocation test

68. Posterior instability can also be seen in the thrower. This occurs during the deceleration and follow-through phases of throwing when the arm horizontally adducts and internally rotates. During this motion, the posterior capsule is stressed and posterior labral injuries can also occur. Stretching of the posterior capsule in this fashion irritates and inflames the capsule, which results in pain and inhibition of the posterior rotator cuff musculature. This muscular inhibition, if unaddressed, eventually results in tendon fatigue and microfailure in addition to increased instability. Clinically, posterior instability can be determined through a posterior drawer test and a posterior fulcrum test.

69. Most athletes exhibiting glenohumeral laxity without associated labral detachment can be treated with a conservative treatment program. The program consists of temporarily decreasing the stresses from throwing, normalizing the motion of the shoulder, and improving the dynamic stability through muscular strengthening and neuromuscular control. Once the athlete’s shoulder pain has subsided, a gradual return to throwing may begin. If a conservative program is unsuccessful after 2 to 3 months, a surgical procedure may be warranted.

70. BICEPS BRACHII TENDON PATHOLOGY Biceps activity requires during the cocking and acceleration phases but a high level of biceps activity requires during the follow-through phase. During this later phase,the role of the biceps is in deceleration of the elbow joint. Because of the eccentric deceleration action of the biceps brachii , overuse tendinitis of the long head can occur. Also, anterosuperior shoulder stability may be enhanced and assisted by biceps activity especially during the throwing movement. Therefore, both activities place considerable stress on the biceps musculotendinous unit and can lead to inflammation of the biceps. Biceps pain has a variety of causes, including biceps instability, tendinitis, tendinosis , SLAP lesions, rotator cuff failure, capsular inflammation, and hypermobility of the glenohumeral joint.

71. The diagnosis of biceps tendinitis is made on clinical examination through palpation, resisted muscle testing, and special tests. The biceps should be emphasized in an appropriate exercise program using concentric and eccentric muscle contractions to control the rapid elbow-extension moment during the follow-through phase.

72. GLENOID LABRUM TEARS During the throwing motion, the glenohumeral joint receives large compressive and shear forces, as well as distraction forces, as the humeral head moves from anterior to posterior during the phases of throwing. These large compressive and shear forces can injure the glenoid labrum, resulting in degenerative tears, frank tears, or labral detachments from the glenoid . A common location for labrum tears is in the posterosuperior and superior portion, where the long head of the biceps attaches. During the deceleration and follow-through phases of throwing, the biceps acts at the elbow joint to decelerate the arm, slowing the extensor movement.

73. Because of the large stabilizing muscle activity of the biceps across the glenohumeral joint, an avulsion tear of the biceps or of the biceps-labrum insertion can result. During the follow-through phase, the humeral head translates posteriorly and can cause degenerative tearing of the labrum. Another type of labrum lesion is the superior labrum anterior-posterior (SLAP) lesion. A commonly seen labrum tear in the throwing athlete is the posterior or posterosuperior labrum tear. During the follow-through phase, the humeral head translates posteriorly and can cause degenerative tearing of the labrum. Another type of labrum lesion is the superior labrum anterior-posterior (SLAP) lesion.

74. THROWERS ELBOW

75. The elbow undergoes significant stress during the throwing motion of an overhead athlete. The forces generated in the various phases of the throwing arc are distributed through the soft tissue and bone of the elbow joint. In baseball players, repetition leads to attritional damage to the elbow. The specific constellation of injuries suffered in baseball . These injuries include : 1. medial UCL tears, 2. ulnar neuritis, 3. flexor- pronator injury, 4. medial epicondyle apophysitis or avulsion, 5. valgus extension overload syndrome with olecranon osteophytes , 6. olecranon stress fractures, 7. osteochondritis dissecans (OCD) of the capitellum , 8. loose bodies.

76. Coronal slice of an MRI demonstrating a medial UCL tear

77. PATHOPHYSIOLOGY OF ELBOW INJURIES Elbow injuries in baseball pitchers from medial tension overload to extension overload to lateral compression overload. These injury patterns can be explained by one mechanism: valgus extension overload syndrome. During overhead throwing, a large valgus force on the elbow created by humeral torque is countered by rapid elbow extension creating significant tensile stress along the medial compartment, shear stress in the posterior compartment, and compressive stress in the lateral compartment. Repetitive, near-failure tensile stresses create microtrauma and attenuation anterior bundle of the UCL, leading to progressive valgus instability. Continued shear stress and impingement in the posterior compartment lead to olecranon tip osteophytes , loose bodies, and articular damage to the posteromedial trochlea in the continuum of valgus extension overload syndrome .

78. As the UCL becomes incompetent, the osseous constraints of the posteromedial elbow become important stabilizers during throwing. Subtle laxity in the UCL also leads to stretch of the other medial structures, including the flexor- pronator mass and ulnar nerve. Extrinsic valgus stresses and intrinsic muscular contractions of the flexor- pronator mass lead to tendonitis. Ulnar neuropathy is common given the superficial position of the nerve. The nerve is susceptible to injury from traction, compression, and irritation at the medial aspect of the elbow. In any overhead throwing athlete, UCL attenuation or failure must be ruled out but should not be the only pathology considered.

79. Gleno humeral internal-rotation deficit Commonly seen in overhead throwers. Contracture of posterior capsule or posterior band of inferior glenohumeral ligament. Centre of rotation of humerus shifts posterosuperiorly . Leads to increase in length of the anterior aspect of the capsule. Decrease contact point of anteroinferior aspect of capsule with the proximal part of the humerus. Results in excessive external rotation. Biceps anchor peeled back results in injury to posterior superior structures(labrum). Further laxity of anterior capsule leads to torsional failure of rotator cuff which can further leads to rotator cuff tear and SLAP leasion .

80. GIRD Andrews and Wilk proposed that the repetitive micro trauma associated with throwing leads to tissue fatigue, inflammation, decreased muscle performance with resulting instability, and ultimately tissue damage. 10 which can be underlying cause for posterior capsule thickness and then tightness. The Glenohumeral internal rotation loss can be due to two reasons a: due to bony remodelling, b: posterior capsular/cuff contracture 1 . Contracted posterior/inferior capsule will not permit full external rotation of the humerus. In an effort to “find the slot” the thrower will begin to rotate around a new instant centre of rotation – one that is more posterior and proximal. In essence, a tightened posterior inferior capsule will drive the humerus more proximally and posteriorly . The concomitant posterior shift in humeral head contact, tightening of the posterior capsule, and anterior laxity can also result in significant rotator cuff pathology by a mechanism termed posterior superior glenoid impingement

81. Clinical presentations -more than 25 degrees loss of internal rotation can be upto 50 degrees in throwers. Increase in external rotation range-30 degrees. Rehabilitation - kibler studied that posteroinferior capsule stretching group improved more than routine exercise group. 38 % decrease in the occurrence of shoulder problem was found.

82. phases Duration Kinematics kinetics Proper mechanics Pathomechanics WIND UP (preparatory phase) Elevation of lead leg to highest & pivots around stance leg 0.5-1.0 sec Shoulder flexed,abduct-ed with elbow flexed to 45 degrees. Mild tension in the muscles of shoulder girdle( supraspinatus,ant . and middle deltoid and clavicular portion of pectoralis major) and elbow - biceps,brachii and brachioradialis . Hip - lead leg flexors(concentric) and abductors(isometric) and extensors(eccentric) Stance leg bend slightly by eccentric contraction of quadriceps. Keeps COG over the back leg to allow generation of maximum momentum once forward motion is initiated to upper limb to the ball. If momentum falls prematurely,kinetic chain will be distrupted leads to greater force from the shoulder to propel ball at top velocity.

83. Phases Duration kinematics kinetics Proper mechanics Pathomechanics Stride phase Lead leg begins to fall and moves towards the target and 2 arms separates. 0.5-0.75 sec Lead foot contacts the ground. Increased distance between legs. Pelvis achieves maximum rotational velocity(400-700 deg/sec). Lumbar hyperextension. Knee and hip stance -extension. Stride -hip and knee flexion(45-55deg) Shoulder -90 degrees and external rotation-60 Elbow -80-100 degrees. Deltoid is very active. Rotator cuff- supraspinatus is active more. If front foot open position-increase shoulder anterior force to 3N. Stride length-70-80% of atheletes height. Front foot inwards-5-25 degrees. Decrease stride length-decreases ball velocity. Closed-block rotation of pelvis & decrease contribution from lower extremity segments. Open foot angle- too early pelvic rotation-early dissipation of ground reaction forces and LE contributions- hyperangulation and arm lag-increased stress on medial elbow and shoulder due to arm fatigue.

84. phases Duration Kinematics kinetics Proper mechanics Pathomechanics Arm cocking phase- lead foot contact to maximal shoulder external rotation 0.10-0.15 sec Upper body rotated towards the target Pelvic maximal external rotation Lead knee begins to extends. 10-20 deg horizontal abduction. Scapula retracts and rotates upwards Shoulder -Increase activity of teres minor and infraspinatus to resist anterior forces. Supraspinatus is least active.provides GH joint compressive forces of 550-770 N. Rhomboids,levator scapulae and trapezius activity. Pelvic rotation followed by upper trunk rotation, shoulder externally rotates and trunk arches. Poor timing between pelvic rotation & upper trunk rotation decreases ball velocity leads to decrease internal rotation torque. Abduction and external rotation-posterior band of inferior GH ligament-bowstringing effect leads to

85. phases Duration Kinematics kinetics Proper mechanics Pathomechanics Arm cocking phase- lead foot contact to maximal shoulder external rotation 0.10-0.15 sec Late cocking- elbow -95 deg flexion. shoulder External rotation-165-175 degrees. Abduction-90-95 degrees. Horizontal adduction-10-20 degrees. As torso rotates increase activity of anterior deltoid & p.major to bring throwing extremity into horizontally adducted position of 15-20 deg. Late phase-inc. activity of serratus anterior. Elbow- max . valgus torgue (64%) flexors and pronator counter torque(64 Nm). Increase biceps activity. External rotation allows accelerating forces to acts over the longest distance,greater prestretch will leads to the greater elastic recoiling effect. posterior superior shift of humeral head-can leads to rotator cuff & labral pathology. Excessive horizontal adduction,external rotation and elbow flexion increase shoulder and elbow kinetics.

86. phases Duration Kinematics kinetics Proper mechanics Pathomechanics Acceleration phase Phase between maximum external rotation and ball release 0.03-0.04sec Trunk continues to rotates and tilt. Scapula protracted to maintain stable position of head of humerus to rotate internally and horizontal adduction. Arm-175-100 deg internal rotation in only 42-58 ms. Internal rotational velocities high-7000-9000 deg/sec Elbow- from 90-120 deg flexion to 25 deg extension at ball release. Transfer of potential energy to the upper extremity. Maximal activity of subscapularis at this phase. Max.activity of serratus anterior. Biceps flexion torque-61 Nm just before ball release. Transfer of centrifugal force to elbow helps in extension and concentric activity of triceps. Decrease time between max.shoulder internal rotation and inc.trunk tilt at ball release increase ball velocity. Elbow extension followed by shoulder internal rotation.

87. phases Duration Kinematics kinetics Proper mechanics Pathomechanics Acceleration phase Phase between maximum external rotation and ball release 0.03-0.04sec Max.extension angular velocity at elbow just before ball release-2251 deg/sec. Radioulnar -pronation 90 deg in 10 sec. Lead leg -hip flexion and knee extension. Forward movement of trunk -30-55 degrees. Max angular velocity-300-450 deg. Shoulder abducted approx-90-110 deg Ar.-10-15 deg behind. Inc.activity of rectus abdominus,obliques and lumbar paraspinals . Inc. activity of rectus femoris Lead leg hip flexion & knee extension- inc.angular momentum of trunk. Trunk tilt allows acceleration to greater distance-more forces transferred to the ball. Inc.knee extension at ball release-increases the velocity. Dec.knee extension velocity- dec.ball velocity. Dec.shoulder abduction- inc.elbow varus torque. Decrease forward tilt-decrease velocity of ball. >110 deg abduction can leads to rotator cuff impingement.

88. phases Duration Kinematics kinetics Proper mechanics Pathomechanics Deceleration Between ball release & max.humeral internal rotation and elbow extension 0.03-0.05sec Ends with shoulder internal rotation to 0 deg. Abduction -100 deg Horizontal arm adduction-35 deg. Arms continues to adduct and internally rotates. After ball release elbow flexion-25 deg and abduction-93 degrees. Violent phase,greatest joint loading,excessive posterior(400 N)& inferior shear force(300 N)anterior compressive forces >1000 N. Inc.eccentric contractile loading of teres minor,infraspinatus & posterior deltoid) Increase biceps & brachialis activity to decelerate the rapidly extending elbow & pronating elbow. Teres minor activity highest to resist anterior humeral head translation ,horizontal adduction & int.rotation . Movement of entire body helps in dessipation of energy of arm. Posterior capsule and soft tissues reaction leads to GIRD.

89. phases Duration Kinematics kinetics Proper mechanics Pathomechanics Follow through phase <1 sec Horizontal adduction increase to 60 degrees. Rear leg comes forwards. Muscle firing decreases and decrease joint loading and minimal forces. Movement of entire body helps to dissipate energy. forward leg assisst in coming to balanced position.

90. Physics principles behind throwing

91. Physics of throwing The throwing activity starts with large base segments( hip,trunk and pelvis) & terminates with smaller base segment( shoulder,upper arm forearm and hand). Segments involved in throwing-lower extremity,pelvis,trunk,shoulder girdle,upper arm,forearm and trunk.These segments moves around joint at their axis. Rotational inertia A measure of a body's  resistance  to angular acceleration angular acceleration for a body segment by applied torque is indirectly proportional to segment’s rotational inertia. Depends on mass and distance between axis of rotation. More the rotational inertia less will be the angular acceleration of segments.

92. Throwing body follows the law of conservation of momentum (product of angular velocity and rotational inertia of a system remains constant). Two types of forces acts on the throwing athelete – external - athelete applies force to the ground,an equal but opposite force is applied by the ground to the athelete,this force adds both angular and linear momentum to the system. Internal- deceleration of pelvic segments accelerates the trunk segment,angular momentum lost by the pelvis is gained by the trunk segment,deceleration of trunk segment accelerates the arm segment.This process continues angular momentum finally transferred to the hand segment with release of ball.

93. Determining factors for maximal distance Release velocity -greater release velocity produces greater distance. Release angle -optimal release angle produces greater distance. Release height -greater release height produces greater distance. Aerodynamics

94. Aerodynamics Aerodynamic forces depends on- ball velocity and surface roughness . Low ball velocity & smooth ball -generates area of positive pressure in front and negative area in along their surfaces as the air speeds up and this area of negative pressure extends to the rear of the ball,generating a significant drag forces. High velocity and rough surface - velocity,values of forces decreases with surface roughness ,the flow of air becomes turbulent,such flow still generates a positive pressure at front of the ball.negative pressure at the sides and rear of the ball reduced,thus drag force is less for a rough ball.

95. Fig;showing aerodynamic forces on a ball moving through air. A)low velocity balls regardless of surface roughness,pass smoothly through air generating an area of positive pressure in front of them & an area of negative pressure along their surfaces as the air speeds up to go around the ball,this area of negative pressure extends to the rear of the ball,generating a significant drag force. B)same velocity with increased roughness ,flow of air around the ball becomes turbulent.still positive pressure in front of ball.However,the area of negative pressure at the sides & rear of the ball is reduced.Thus,counternuitively,the drag force is less for a rough ball than for a smooth ball.

96. Aerodynamics

97. Aerodynamics -Magnus effect When spinning ball is thrown,it deviates from its usual path in flight. Spin in air,air around sets in rotation in the form of concentric stream lines. If the ball is spinning as well as moving linearly,the stream lines set at the top of the top of the ball due to two types of motion are opposed to each other. Velocity of air flow is greater below than above the ball and pressure up is more,resultant force F acts upon ball at right angle to the linear motion is down. This force provides necessary centripetal force to move the ball along the curved path.This effect is called magnus effect.

98. Types of pitches Commonly used slider,changeup and curveball. 1. SLIDER -mimics the appearance of fast ball in arm speed & motion with slightly decreased ball velocity & the addition of horizontal plane ball movement(break) to fool the hitter. Arm position and grip remains same as fast ball,but the pitcher supinates the forearm until ball release during late acceleration,generating rotation of the ball around the central axis,which generates horizontal plane movement from right to left for right handed pitchers. Fingers-3 and 9 o’clock position.

99. CHANGE UP -the change up is thrown with the same arm slot & motion as fast ball. The spin generated on the ball is in the same direction of the fastball(backspin)with a lower velocity to distort the hitter’s timing. The ball is positioned deeper to palm to decrease the velocity of pitch. 2. CURVEBALL -is thrown slower,with different trajectory and spin. Pitcher’s fingers are located on top of the ball at release to generate a forward rotation(12 to 6o’clock rotation) that allows vertical plane movement(break or drop).

100. Comparision of throwing mechanics in overhead throwers with respect to the pitch types Eschamilla et al studied the throwing mechanics in overhead atheletes . Fastball are thrown with more pelvis and upper torso angular velocities & stride length. Peak shoulder angular velocities were significantly greater when throwing fastball then curveball. Curveball was thrown with more knee flexion,greater forward and lateral trunk tilt,increased shoulder horizontal adduction at ball release. Shoulder abduction higher during acceleration in the curveball versus fastball. Fastball-lead knee continues to flex throughout much acceleration & is greater at ball release.

101. Research-elite sports medicine & center for motion analysis) KINEMATICS Wrist remains extended more for fastball then in curveball. Highest wrist ulnar angular velocity for curveball(360±47 deg). Wrist remains pronated for the fastball as compared to curveball. Elbow angular velocity were slightly higher for fastball than curveball. Overall arc of motion for glenohumeral joint was greater for fastball.(fastball 124±12 deg vs. curve 117±17 deg). Peak velocity of GH internal rotation velocity was higher for the fastball(3619±656deg/sec) vs. curveball(3409±722 deg/sec)(p=0.023).

102. KINETICS Elbow peak varus moment-fastball-59.6±16.3 more as compared to curveball varus moment of 54.1±16.1Nm(p<0.001). Shoulder internal rotation moment-fastball=59.8±16.5Nm curveball=53.9±15.5Nm These findings are contrary to the long held belief that throwing a curveball placed the arm at a higher risk of injury than throwing a fastball. Stress on elbow & shoulder were directly related on ball velocity-lower force at joint with the slower curveball & higher force with the fastball.

103. References Sports physiotherapy -applied science and practice( zuluaga and christopher briggs ) Atheletic injuries and rehabilitation ( zachazewiski ) The atheletic shoulder -book Sports injuries and rehabilitation -by cars petersons-3 rd edition. Post surgical sports rehabilitation (Robert c.mashe ). The shoulder and the overhead atheletes ( sumant G.krishnan ) Sports specific rehabilitation ( robert donatelli ) Research articles Internet You tube

104. THANKYOU