Throwing Biomechanics

Authors

Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

*Throwing arm will be considered I/L

Phases

Wind Up

• Initial Movement to Maximum Knee Lift
• Necessary:
  • I/L rotation
  • Relative I/L Hip IR
  • I/L SLB
  • Lead HF (end range)
  • I/L Hip ext
  • Stance (I/L) leg ext/IR
  • stride leg max HF
  • Upright trunk with I/L rot
  • Eccentric trunk/shoulder load
  • Critical events and considerations:
    • SLB and stance stability (lumbopelvic)
    • Load hip, min shoulder mm activity

Early Cocking

Defined as Maximum Knee Lift to Lead Foot Contact

• Stance leg EXT/ER/ABD with pelvic Rot
• Stride leg drives trunk and UE eccentric load
  • This powerful stride before front foot strike is important

Increased hip/pelvic Rotation

• Increased GHJ HorABD stress (Laudner 2019)
• Increased Elbow valgus (Laudner 2019)

Decreased hip/pelvic Rotation

• Increased GHJ HorADD (Laudner 2019)

Late Cocking

Characterized by Lead Foot Contact to Maximal Shoulder ER

• Trunk begins C/L rotation (following the pelvis)
  • Trunk is moving faster than the shoulder (relative HorABD)
• C/L arm: Remains closed
• I/L arm
  • GHJ Max ER & Max ABD
• Scapula: Retracts to create stable base
• Foot placement
  • Angled 15° from 180°

Note

A focus of a clinician during this phase should be foot placement

Acceleration

Maximal Shoulder ER to Ball Release

• Hips & Trunk rotate the shoulder to “ball release point” of 90° rotation
• Muscle function transition
  • Internal rotaters are eccentrically working as the shoulder moves to max ER then transition to concentric activity during this phase

Deceleration

• Ball Release to Maximum Shoulder IR
• Arm crosses body (hor-add)

Follow Through

• Maximum Shoulder IR to Body Stops Moving

Stride Length

• Professional: Stride length = 85% of height
• Youth: Stride length = 65% of height