Scuba is right, TENS is not a gimmick, it relieves pain.
No drugs, no downside.
I have used it for back pain as well, used to allow me to work when I couldn't stand up straight due to pain.
Put the electrodes on, put the TENS unit in my pocket, pain under control.
No reason to exclude it, it provides immediate relief.
Using it doesn't prevent you from doing exercises.