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Technical Details

  • Variable Type: Discrete Metric
  • Data Type: Boolean
  • Units: True/False
  • Column Name: sway
  • Measurement: Position of front knee, head midpoint, or body center of mass relative to back leg
  • Threshold: 15 cm (~6 in) of forward/backward movement in the 0.4 s around max knee raise event

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Description

Sway is a binary indicator that flags excessive backwards body motion (away from home plate) around max knee raise. Occurs if the pelvis keypoint (center of the hips) moves backwards more than 15 cm (~6 in)

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Use Cases

  • Balance analysis
  • Movement efficiency assessment
  • Stability evaluation

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Corrective Drills

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1. Balance Beam Knee Raise

Stand on a 2×4 or balance beam oriented toward the plate. Perform the leg lift and hold at max knee raise for 2–3 seconds without wobbling forward or backward. This isolates the balance component and makes any sway immediately apparent through loss of footing. Perform 3 sets of 10 reps. Search YouTube: baseball pitching balance drill knee raise sway fix

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2. Dowel Rod Posture Check

Hold a dowel or PVC pipe vertically against the back (touching head, upper back, and tailbone). Perform slow-motion pitching reps and monitor whether the dowel stays vertical through the knee raise. Swaying backward will cause the rod to tilt, giving instant tactile feedback. Perform 15–20 reps. Search YouTube: baseball pitching dowel rod posture drill balance

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3. Hip Hinge Load Drill

Rather than initiating with a backward weight shift, practice loading directly into the back hip by hinging (pushing the back hip out laterally) while keeping the pelvis centered over the back foot. This trains forward-neutral momentum from initiation to max knee raise without the backward sway. Perform 20 reps before bullpen or live throwing. Search YouTube: baseball pitching hip hinge load drill balance sway