Swimming stroke analysis, frame by frame.
Film from the poolside or from under the surface, then step through the catch one frame at a time and measure the elbow instead of estimating it.
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What the readings tell you in swimming
33 body landmarks tracked in your browser, with joint angles measured in degrees on every frame. Motion phase and footwork readings are quick landmarks, not scored judgments — the coaching is still yours.
Elbow angle through the catch
The high-elbow catch is the hardest thing to coach by description and the easiest to show as a number. The elbow is measured on every frame of the pull.
Shoulder position and roll
Both shoulders are tracked, which makes body roll visible as a measurement rather than something you judge by eye from a moving pool deck.
Knee angle on the kick
Knee angles separate a hip-driven kick from a knee-driven one, which is usually the difference between propulsion and drag.
Body line and balance
Stance and balance readings are built for athletes on their feet, so treat them as approximate in the water. The joint angles and the frame-by-frame scrub are the tools that carry here.
Moments coaches stop the tape on
- 01Catch: elbow position at the front of the stroke
- 02The pull-through, and where the hand slips rather than holds
- 03Breathing: head rotation and whether it lifts
- 04Push-off and streamline off the wall
- 05Kick: hip-driven versus knee-driven, seen in the knee angle
Filming in and around the pool
- Above-water from the poolside shows the recovery and the breath. Below-water shows the catch. If you can get both of the same swim, tag them to the same swimmer and compare them.
- Film square to the lane rather than down it. A head-on shot foreshortens the arm and makes the elbow angle unreadable.
- Water throws light around badly. Film with the sun or the window behind you, and avoid the lane with the surface glare.
- Keep the whole body in frame including the feet — the kick read depends on the ankles being visible.
Swimming questions, answered.
Does pose tracking work underwater?
It tracks what the camera can see clearly. Underwater footage with good light and a close, square angle tracks well; murky or distant footage degrades. Bubbles across the body are the usual culprit when landmarks jump.
Are the footwork and balance readings useful for swimming?
Honestly, not very — they are derived from ankle and hip position for an athlete standing up. For swimming, the joint angles, the frame-by-frame scrub and the drawing tools are what you will use.
Can I compare a swimmer against themselves mid-season?
Yes. Film the same stroke from the same position a few weeks apart, anchor both clips at the catch, and link them so they play as one. Progress that a swimmer cannot feel is usually obvious side by side.