Your Downswing Duration
In a quarter of a second, your body executes one of the most complex athletic movements in sports.
Cameras get 7 frames. We get 416 IMU samples and 250 EMG readings. Let's break it down.
The 250ms Breakdown
Weight shift initiates. Pelvis begins rotation.
Core engages, shoulders pull. Peak pelvis speed (477°/s) reached and begins deceleration.
Arms accelerate as shoulders decelerate. Wrist cock maintained. The "lag" window.
Wrist release. Club head reaches peak velocity (2500°/s). Ball contact at 250ms.
8 Data Sources
Lumbar
Pelvis Rotation
Above belt line · Chain origin
Thoracic
Torso Rotation
Below C7 · Shoulder-hip separation
Forearm
Arm Speed
Dorsal mid-forearm · Lag window
Hand
Terminal Speed
3rd metacarpal · Club release
Quad
Ground Push
L. leg, lateral thigh · 30-35%
Glute
Hip Rotation
Left, upper outer · 25-30%
Oblique
Core Rotation
Left, below ribs · 20-25%
Lat
Arm Pull
Right, below scapula · 15-20%
The Data Gap
That's 95× more data than a camera alone — in the same 250ms window.
What We Find
Peak-to-Peak Gap
The timing window between each segment's peak velocity. Pro gap: 30ms. Amateur: 50ms+. A camera can't see the difference.
Muscle Activation Range
Your forearm flexors might fire at 40% when they should be at 85%. EMG shows the deficit. Training corrects it.
Sequence Overlap
When two segments accelerate simultaneously instead of sequentially. Energy leaks out of the chain.
Fatigue Drift
EMG shows muscle activation dropping 20% in late rounds. Your technique "fails" because your muscles give out — not your brain.
data points per swing.
One AI brain to make sense of it all.
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