I know it's just for educational use (thanks!), but fun to think through what it would take to make this into a fully functional app.
Exercises that don't involve arm movement would be impossible to classify. An extra sensor on the leg might be enough to a) handle cases where just leg movement is involved and b) capture body position for static exercises like planks and wall sits.
Yeah that is interesting and something that I wondered about while I wrote this post. There's only so many exercises you can model with a watch on your left wrist (at least with the accelerometer and gyroscope data). Another example that's been on the back of my mind was if I tried to go a step beyond classification to count reps for an exercise like single arm raises, would I be able to tell when I do a rep with my right arm? Definitely something I want to go a little deeper on in subsequent posts to find the limit of what we can and cannot classify. Like you said, I reckon static exercises would be pretty difficult and there would be a pretty high miss on those unless we had access to additional info.
check out Gymatic featured in Apple Watch app store. Exercise classification + rep counting. I am the developer and we already have a lot of active users using the solution in Gym.
Exercises that don't involve arm movement would be impossible to classify. An extra sensor on the leg might be enough to a) handle cases where just leg movement is involved and b) capture body position for static exercises like planks and wall sits.