3DSeg/JointAngles vs Prowess

3D Seg/Joint Angles measures three-dimensional Cardan/Euler angles of body segments and joints using your iPhone's built-in motion sensors — no external hardware required. Designed for biomechanics researchers, clinicians, physiotherapists, athletic trainers, and students, the app uses your iPhone's accelerometer, gyroscope, and magnetometer to compute the three rotational angles (about the X, Y, and Z axes) that describe how a body segment or joint has moved from a defined starting position. HOW IT WORKS Place the iPhone on a body segment (e.g., thigh, shank, forearm). Press "Set Initial Position" to define the reference frame. The app then continuously reports the three angles — in degrees — that describe the 3D rotation from that starting position to the current position, in real time at 60 Hz. ROTATION SEQUENCES Six standard Cardan/Euler rotation sequences are supported: • X-Z-Y (default, recommended for most lower-limb joints) • X-Y-Z • Y-X-Z • Y-Z-X • Z-X-Y • Z-Y-X Select the sequence that matches your anatomical convention. Angles are always displayed in X, Y, Z order regardless of the sequence chosen. PHONE AXES • X axis — points to the right side of the phone (medial-lateral; flexion/extension) • Y axis — points toward the top of the phone (longitudinal; internal/external rotation) • Z axis — points out of the screen (anterior-posterior; abduction/adduction) Positive and negative angle signs follow the right-hand rule applied to each physical axis of the phone. RECORDING AND EXPORT Start and stop recording with a single tap. After recording, the three angles are plotted over time directly in the app. Export the data as a CSV file via email, AirDrop, or any share destination for further analysis in Excel, MATLAB, or R. KEY FEATURES • Real-time 3D angle display at 60 Hz • Six selectable Cardan/Euler rotation sequences • Calibrate to any starting position • Built-in angle time-series plot • CSV export via iOS Share Sheet • Works completely offline — no internet required • No account or login needed • All data stays on your device IMPORTANT NOTES • For accurate results, hold the phone still during calibration • The Z axis requires the magnetometer to be valid — keep the phone away from strong magnetic fields • This app is intended for research, education, and rehabilitation purposes. It is not a certified medical device.

Your watch tells you how far and how fast. Prowess tells you how well you moved — and the one thing to work on next. A small sensor clips to your shoelaces and measures every stride at the foot, where running actually happens: how hard you land, how quickly you load, where your foot comes down, and how your rhythm holds up as you tire. After your run, everything syncs to your phone over Bluetooth automatically. YOUR PROWESS SCORE Two numbers that capture the quality of your running: Economy (how efficiently you move) and Impact (how much force you take on, stride after stride). Watch them respond as your form changes — quality of movement, not just quantity of training. STRIDE BY STRIDE, NOT AVERAGES Scrub through any run step by step. See exactly when your cadence slipped, when impact crept up, and how the last mile compared to the first. SEE WHICH PRO YOU MOVE LIKE Compare the shape of your form against elite reference profiles — trail runners, road racers, triathletes — and see your closest movement match, plus the single gap that would move you closer. TRAIN WITH A GOAL Pick what matters and Prowess focuses on the metrics that move it: - Return to Run — rebuild after a setback, carefully - Optimize Stride — run more efficiently - Increase Mileage — build volume without breaking down - Safe Walking — movement insight at walking pace - In-Depth Gait Report — the full picture LIVE FEEDBACK Start a guided session and get real-time cues on cadence and landing while you run — coach a change and watch it happen. ONE SENSOR OR TWO One pod gives you the core picture. Add a second for true left/right symmetry — one pod per foot, nothing inferred. FITS WHAT YOU ALREADY USE Send runs to Strava and Apple Health. Tag your shoes to see how your form changes as they wear. HONEST BY DESIGN Prowess is a training and measurement tool, not a medical device. It won't diagnose anything, and when a number is an estimate, the app says so. Your data belongs to you — never sold, never used for advertising, and you can delete your account (and everything with it) right from the app. REQUIRES THE PROWESS SENSOR Recording runs requires the Prowess clip-on sensor. Without it you can explore the app, but the numbers come from the hardware.