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Technical Details

  • Variable Type: Discrete Metric
  • Data Type: Boolean
  • Units: True/False
  • Column Name: flying_open
  • Measurement: Trunk angular velocity peak timing and X-factor at foot contact
  • Threshold: Trunk angular velocity peaks before foot contact AND X-factor within 5° of neutral (0°) at foot contact

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Description

Flying open is a binary indicator that flags early trunk rotation during the pitch. It occurs when the trunk angular velocity is peaking before foot contact and the X-factor (hip-shoulder separation) is within 5 degrees of 0 at foot contact.

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Use Cases

  • Timing assessment
  • Rotation sequencing evaluation

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Corrective Drills

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1. Stay-Closed Stride Drill

Perform slow-motion stride reps with an emphasis on keeping the front shoulder and hip closed (pointed toward the catcher) until the front foot lands. Place a bat or cone along the glove-side hip as a visual guide — the front of the body should stay “behind” the bat until foot contact. Perform 20 reps, then integrate into full throws at 60% effort. Search YouTube: baseball pitching stay closed stride drill flying open fix

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2. Glove-Side Pull Drill

Attach a light resistance band to the glove wrist, anchored on the glove-side. During the stride, the glove hand is pulled outward and then tucked back to the chest only after foot contact. This forces the front side to stay closed longer and delays trunk rotation until the lower body has landed. Perform 3 sets of 10 reps. Search YouTube: baseball pitching glove side pull drill stay closed front shoulder

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3. Hip-Shoulder Separation Overload Drill

Deliberately exaggerate the hip-shoulder separation: drive the hips hard toward the plate first, then consciously hold the trunk and shoulders back until the foot lands. This “over-teaches” the proper sequencing by making the pitcher feel the difference between hip rotation and trunk rotation. Start with walk-through reps, then build to full effort. Perform 15–20 reps. Search YouTube: baseball pitching hip shoulder separation drill overload sequencing