The document is a detailed biomechanics report for a single golf swing performed by Eli Willits, captured with an AMM upper‑body system and SwingCatalyst force plates. It presents phase‑by‑phase quantitative data on vertical ground reaction force (Fz) expressed as % body weight, horizontal ground reaction forces (Fx lateral, Fy anterior‑posterior), center‑of‑pressure (CoP) lateral position and velocity, free moment about the vertical axis (Tz) that drives axial rotation, bilateral asymmetry between lead and trail sides, and pressure distribution under each foot. The data are aligned to swing phases (P1, P2, PP3, P4, P6, P7, P8, P9) and an AMM clock timeline, providing a cause‑effect mapping of ground reaction forces to motion outcomes for a 92 mph clubhead speed swing with 16° launch angle. The report is purely quantitative, with no narrative interpretation, reflecting the author’s focus on precise sensor‑based measurement and phase‑specific force analysis.
Topics
Phase‑Resolved Vertical Ground Reaction Force (% Body Weight)
Tabulated Fz values for each swing phase (P1‑P9) showing how vertical loading evolves throughout the swing.
Horizontal Ground Reaction Forces – Lateral (Fx) and Anterior‑Posterior (Fy) Components
Separate tables for Fx (left/right) and Fy (toe/heel) across swing phases, highlighting directional loading patterns.
Center of Pressure Lateral Position and Velocity
CoP X positions and lateral velocity (m/s) per phase, indicating weight‑shift speed and foot‑placement dynamics.
Free Moment (Tz) as Driver of Axial Body Rotation
Phase‑specific Tz values that quantify the torque about the vertical axis contributing to pelvis‑thorax rotational velocity.
Bilateral Asymmetry and Load Distribution Between Lead and Trail Sides
Percent differences in loading (Lead‑Loaded vs Trail‑Loaded) and pressure distribution under each foot across phases.
Methodology Snapshot – AMM Upper‑Body + SwingCatalyst Plate Configuration
Brief reference to the sensor setup (AMM clock timing, force plates) and swing parameters (92 mph EV, 16° launch angle).