Well.....I've over done it to my elbow weight lifting before, to the point I couldn't turn a door knob without extreme pain. The only cure was rest for a long period, though my understanding is that some will go for cortisone injections.
Now during that time frame I cut back on detecting, but didn't stop completely. I suppose I might have tried one of those swingy thingy bungy supports, but I didn't. What I did do was change the way I held and swung the detector. My normal beach swing is 180+ degrees to get as much coverage per step as possible, so my elbow is not only extended out in front of my body, but being slightly pronated as my arm crosses in front of my body. With a heavier coil over many hours this really puts some stress on the elbow. Also being in the water with resistance can also hammer the elbow, if you tend to beat the water to a froth like I do.
So here's what I did, reluctantly:
A. I stayed out of the water.
B. I anchored my elbow to my side with no extension out in front of my body. This leaves a very short swings, maybe 70 degrees. To compensate I swung my body about 35 degrees as I stepped and used my arm/elbow for the other 35 degrees, but always keeping my elbow stationary with no pronation.
So I looked a little silly, kind of like a weeble wobbling down the beach. But I was detecting!
On the Lesche........if you're in an area where you can do some damage(not a manicured lawn) I would look into using a relic shovel which will take the stress off of your arms/wrist. I use one of the small16 or 17 inch D-handle planting shovels when I can if land digging. I also dig a triangular plug, since roots tend to run in straight lines and a square plug tends to hit the same root twice. You also only make three cuts, as opposed to 4, saving 25% of your time.
HH
BarnacleBill