Experiment 2: Bench Press Front View Analysis With Keypoint Tables
Approach
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1. Estimate body pose
- Record video of bench press.
- Produce COCO-17 keypoints for each frame, including shoulders, elbows, wrists, hips, knees, and ankles.
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2. Extract frames from video
- Select bottom, mid-point and top of lift.
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3. Generate coaching
- Send each rep's frames and matching measurement table to GPT 5.4 for feedback.
Sample data table: TOP rep 1
athlete-left wrist x/y 3589.3, 1867.4 athlete-right wrist x/y 2063.8, 1919.8 wrist height delta athlete-left is 52px higher athlete-left elbow x/y 3595.2, 2443.8 athlete-right elbow x/y 2058.0, 2496.2 elbow height delta athlete-left is 52px higher athlete-left shoulder x/y 3245.8, 2833.9 athlete-right shoulder x/y 2419.0, 2868.9 shoulder height delta athlete-left is 35px higher
Coaching
Overall Assessment
- Lockout is consistently tilted: athlete-left wrist/elbow/shoulder finish higher than athlete-right on all 5 top frames.
- Bottom position is mostly level at wrists and elbows, so the asymmetry shows up mainly during the press and lockout rather than on the chest.
- Fatigue does not clearly worsen the tilt; rep 5 mid/bottom is relatively level, but the same athlete-left-high lockout pattern remains.
Recommendation
- Pause 1-count on the chest and drive both hands evenly, aiming to keep wrist height matched through the midrange.
- Film grip setup and verify ring placement so the bar is centered evenly over the chest before unrack.
- Keep wrists stacked over elbows and squeeze the bar hard, especially on athlete-right, to clean up the uneven top-end finish.
Rep 1
Strong athlete-left-high tilt through top and mid, but bottom is level; focus on a more even press from chest to lockout with matched wrist height.
Rep 2
Same athlete-left-high lockout and midrange asymmetry with level bottom touch; slow the descent and drive athlete-right to meet athlete-left through the sticking point.
Rep 3
Top is again athlete-left high, while mid and bottom are closer to level; keep the same touch point but finish by pressing both sides together.
Rep 4
Mildest midrange asymmetry of the set, yet lockout still finishes athlete-left high; reinforce even press-out and hold the top symmetrically for a beat.
Rep 5
Mid and bottom are levelest, but top still ends athlete-left high; keep that improved midrange balance and continue pressing athlete-right through to full lockout.