Injury Prevention Related to Pitching

E. David Osinski M.A.

Glenn S. Fleisig, Ph.D.

Biomechanics of Pitching

• Adult pitchers (college & pro)– ASMI 18 studies published in last ten years– All levels (youth thru pro)

– Kinematic (angular displacements and velocities) and kinetic (forces & torques) comparison of baseball pitching among various levels of development. (Fleisig et al, J Biomechanics, 1999)

Results - Position (°)

Youth HS Coll Pro

Stride 85 85 85 86

Ext Rot@ FC 67 64 55 58

Elbow @ FC 74 82 85 87

Knee @ FC 43 50 48 46

Max Elbow 95 100 99 98

Max Hor Add 21 20 20 17

Max Ext Rot 177 174 173 175

Elbow @ Rel 24 23 23 23

Hor Add @ Rel 11 10 9 9

Trunk @ Rel 32 31 33 33

Knee @ Rel 36 43 39 38

Hor. Add 910 890 820 830

Results - Force (Newtons)

Youth HS Coll Pro

Sh Anterior 210 290 350 390

Elb Proximal 400 630 770 910

Sh Proximal 480 750 910 1070

Sh Posterior 160 280 350 390

Significant relationship between kinetic forces at shoulder & elbow joints for variables for pitching mechanics for youth through professional pitchers.

Results - Force (%Weight)

Youth HS Coll Pro

Sh Anterior 39 39 44 44

Elb Proximal 74 85 96 103

Sh Proximal 89 101 113 121

Sh Posterior 30 38 44 44

Significant relationship between forces at shoulder & elbow joints for pitching mechanics variables when adjusted for physical differences.

Wind Up Commencement Movements

High School Stride

Foot Contact

Pelvis = 25° open

Upper Torso = 20° closed

Shoulder:

Abduction = 90°

Rotation = 65°

Elbow:

Flexion = 80°

High School Arm Cocking

Max. Rotation

Shoulder:

Rotation = 175°

Elbow:

Flexion = 100°

High School Arm Cocking

Shoulder:

Anterior Force=290N

IR Torque = 51 Nm

Elbow:

Varus Torque=48Nm

(Weight = 740 N = 170 lb)

High School Arm Acceleration

Arm Acceleration

Elbow:

Extension = 2200°/s

Shoulder:

Rotation = 6800°/s

High School Arm Acceleration

Shoulder:

Proximal Force = 750 N

Elbow:

Proximal Force = 630 N

(Weight = 740 N = 170 lb)

Deceleration & Follow-Through

Pathomechanics

PHYSEAL INJURYLittle Leaguer’s Shoulder

• First by Dotter described in 1953• Described in literature as

– osteochondrosis of the proximal humeral epiphysis

– proximal humeral epiphyseolysis

– stress fracture of proximal humeral epiphyseal plate

– rotational stress fracture

Adolescent Pitcher Shoulder Injury

• Typically males, 12 - 15 years of age• 14 y/o more prone due to rapid growth and more

skilled• Average duration of symptoms before treatment is

approximately 7 months• Associated with quantity and intensity of pitching, age

at which pitching started, use of curveball

PHYSEAL INJURYLittle Leaguer’s Shoulder

Elbow - Anatomy/Mechanics

• Anterior Band of UCL (main valgus stabilizer) attaches to the medial epicondyle apophysis

Elbow - Anatomy/Mechanics

• Increased bone plasticity

• Hyperelasticity permits excessive joint translation

Elbow Injuries

Skeletally immature athletes are susceptible to unique injuries

secondary to:

• Relatively weak growth plates (physes)

• Ligamentous laxity

• Inadequate dynamic strength / stability to resist high biomechanical forces

Medial Epicondyle Apophysitis /

Avulsion

• Most common injury seen in the adolescent throwing athlete

• Caused by acute valgus overload

• X-rays may appear normal

1996 Survey (USA Baseball News, 1996)

• Survey for UUSSA A Baseball

• 28 Orthop. Surgeons & Baseball Coaches

• number of pitches more important than innings

• Increase pitch count limits with ageExamples: 8-10: 50 pitches. 17-18: 90 pitches

• Start using pitches at different ages– Fastball (8), Change (10), Curve (14), Slider (16)

1997-98 Study (Med Sci Sport Exerc, 2001)

• 200 pitchers each Spring (300 total subjects)

• 8-12 years old pitchers in Birmingham

• 50% of pitchers had elbow/shoulder pain during study

• Increased pitches Increased pain risk– 75 pitches/game recommended limit– 600 pitches/season recommended limit

1999 Study (Am J Sports Med, 2002)

• Funded by UUSSA A Baseball• 500 pitchers in Spring• 9-14 years old pitchers throughout Alabama

• Increased pitches Increased pain risk– 75 pitches/game recommended limit (15 batters)– 600 pitches/season recommended limit (120 batters)

• No relation found between mechanics - pain risk• Curveballs/Sliders Increased pain risk

Conclusions - Mechanics

• Successful youth and adult pitchers use similar kinematics.

• Relationship between poor mechanics and risk of injury unproven

Conclusions - Pitch Quantity

• Correlation between pitch count and pain in youth pitchers

• College/Pros use pitch counts to protect pitchers. Youth pitchers should do as well.

Conclusions - Pitch Quantity

 

USA Baseball Medical Committee Recommendations 2003

Age Workload Limit in PitchesGame Week Season Year

9-10 50 75 1000 100011-12 75 100 1000 300013-14 75 125 1000 3000

American Baseball Foundation Thank you

ABF BASIC Program at Rickwood Field