There was a good bit by Joanna Stern in the Wall Street Journal where she hired a professional stuntwoman; she was unable to trick the watch into thinking she had fallen, but the stuntwoman was able to by taking some hard falls.

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&c...

No. You have to really take a hit -- and you have to fail to cancel the 60 second (very loud and annoying) countdown, too.

I can think of a lot of things you can do that will make the portion of your body that the watch is attached to take a really hard hit. How does it not have a high false positive rate?

Exactly. If it is just detecting falling down from standing position, I can imagine several things causing that

It's probably more about instantaneous acceleration. Nothing you can do with your own two arms and legs will ever cause you to experience a deceleration as hard as what happens when you fall from a standing position onto a hard surface. (Unless you ran full-tilt into a brick wall, I suppose.)

It also considers your cardiac rhythm so I would think they trained their model to consider it.

My understanding is they are very specific about this not being able to detect heart attacks - hence why I'm hesitant to speculate about the exact sequence of events above

I hope not, I don't want my smashed head to be ignored just because my heart is still beating.

I have not seen that mentioned anywhere. Is there a reference for that?