Can AI do gait analysis?
Yes, AI can do a gait analysis from a normal phone video, using pose estimation to track your joints frame by frame and measure foot landing, torso lean, knee angles, arm swing and cadence with no sensors.
What the AI is doing
The word AI covers a lot. In gait analysis it usually means one specific thing. A pose estimator. That is a model trained on millions of images of people, and it has learned where a human's ankles, knees, hips, shoulders, elbows and ears are. Show it a video frame and it marks those points.
Do that for every frame of a 15 second clip at 30 frames per second and you have 450 skeletons. The software then watches the ankle rise and fall to find foot strike, midstance and toe-off. At each of those moments it measures angles. That is the whole trick. The full pipeline is here.
So the AI is not watching you run and forming an opinion. It is measuring. The opinion comes after, from comparing your angles to ranges a coach would call good, fair or worth fixing.
What it can measure from a phone
From a side view, a pose model can read the things that matter most:
- Where your foot lands relative to your hip, as a fraction of leg length.
- How far your torso leans from vertical.
- How much your front knee bends at midstance.
- How much your back knee bends in recovery.
- Your elbow angle.
- Where your head sits relative to your trunk.
- Cadence, by counting foot strikes.
Caden currently analyses the side view only. That is still a decent list. It covers overstriding, which is the fault most often linked with shin and knee trouble. See what overstriding is.
What it cannot measure
A camera sees a flat picture. So the AI measures 2D angles in the camera's plane. It cannot measure force on the ground. It cannot see pronation, which is how your foot rolls inward, because the side camera cannot see under your shoe. It cannot measure 3D rotation at the hip or pelvis.
Those need a lab with force plates and many cameras, or a physio with sensors. A tool like Runeasi is built for that clinic setting.
The AI is also only as good as the clip. If you are small in the frame, or the light is poor, the joints wobble and the numbers wobble with them. Caden rejects a clip it cannot read instead of guessing. Read how accurate running form apps are for what to check.
And none of this is a diagnosis. A video can show that your foot lands well ahead of your hip. It cannot tell you why your knee hurts.
On the phone or in the cloud
Some apps run the model on the phone. Others upload the video to a server. Caden uploads: the app removes the audio track first, the clip goes to private storage under your account, and pose estimation runs on Caden's servers. The clip stays stored until you delete the analysis.
For a runner that mostly matters for privacy and for the wait. Upload plus analysis usually takes about a minute, depending on your connection.
How to check it with Caden
- Tap Run a new analysis and film 10 to 20 seconds from the side at easy pace with the phone at hip height.
- When the results load, open Breakpoints and toggle Skeleton. If the joints sit on your actual joints, the AI read the clip well.
- Tap Foot strike to see the frame where your foot touched down, with the landing reach measured for that phase.
- Open Stats after a few runs. The AI measures every clip at the same three moments, so the trend line compares like with like.
FAQ
Is AI gait analysis as good as a lab?
No. A lab measures force and 3D motion. AI video measures 2D angles. For checking landing, lean, knee bend and cadence, the video is enough. For force or pronation, it is not.
Does AI gait analysis need special equipment?
No. A phone camera and something to prop it on at hip height. No sensors, no treadmill, no wearable.
Can ChatGPT do a gait analysis?
Not in the same way. A chat model can describe a still image. It does not track joints across frames or count steps. See can ChatGPT analyze running form.