Elbow strikes are very useful for in close fighting.
The concept of “shearing” I got from Bob Orlando, a fine gentleman and martial arts instructor in Denver CO.
Practise hitting things with your elbow from as many directions as you can think of and from any position. Without actually hitting stuff, you will not get a useful feel for this very strong technique. If it is true that rapists like to turn their victims around so they are behind them to manage them better and avoid identification, then the rear elbow strike is a good rape avoidance strategy, especially with a hammer fist to the groin.
It can be learned without a lot of balance and coordinationing training from martial arts, and since it is not a killing blow, it can be used for self defence without legal liability.