Throwing Biomechanics

Authors
Affiliations

Doctor of Physical Therapy

B.S. in Kinesiology

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

Citation

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