Fall detection while exercising

Being 80 years old I rely on Apple Watch Series 6, to alert my family if I fall. I've had one fall where I was not injured and had to turn off the notification. Then I've had several instances were there has not been a fall and i had to shut off the notification for a false alarm.. However, the other day I was walking in the woods on a trail with my exercise app linked to an outdoor walk, when I took a very serious fall down an inbankment and hit very hard. The Watch sent out no notification which really shocked me! I am now suspecting that the watch will not do fall protection when you are in an exercise mode. I think the Watch just assumed that I was exercising a little harder that day and did not realize it was a fall!