Considering that Chris Rice has never seen anything like this before (and no one else has responded), I will assume I have invented it and will use this as a log of my progress. The short answer of why I am doing this is two fold: I love support lifts, and I feel that my main weakness with feats of strength is a severe imbalance between my wrist flexors and extensors (similar to what arm-wrestlers who specialize in the hook technique experience). That is why I am giving the wrist extensors direct attention.
Will post again.
Some guy no one ever heard of named Franco Columbo said "if it works it works, I don't care what anyone says" - and I'll agree with that statment. A question if I may - with the thumb down (or pinkie up) position you use - it appears to work extensors more towards the pinkie side of the forearm??? True? If so the imbalance in extensors is not in all extensors groups but localized to that area? Have you tried this static hold with a level hand so to speak? If so what do you notice with it that way? It would seem to hit the extensors group more evenly that way?
Haha! That's an obscure reference and I would love to tell you anything you want to know about this lift. Yes my carpi extensor ulnaris is the one that I have the most problems with, and I think that is mainly because anatomically, it is the smallest. This lift is incredibly nuanced; if you look back at the video, you will notice that my pinkie is flat against its side of the dumbbell. That is intentional. On a max effort version of this lift, the best way to keep that extensor from giving you crap is to preform it exactly as you see me do in the video. I think that is because that extensor is much better at ulnar deviating than it is extending, but I'm not sure. If you drop weight, and work with something that isn't your maximum, you will notice that where you position your hand along the dumbbell handle and how you position your wrist changes the direct line of pull--this lift is all about direct line of pull. Lets say that you grip the dumbbell in the dead center and hold the wrist parallel to the floor. Basically, think about lifting with your middle and ring knuckles (mostly middle). You will notice that the carpi extensor radialis brevis does the most work because it is in the direct line of pull. But you will also notice the carpi extensor digitorum, and depending on the angle, the carpi extensor ulnaris will strongly assist (especially on the side of the tendon closest to the ring finger). That being said, I can't do that until I master a weight in the position of the above video. So it is another level of progression for me if you will. You can also grab the dumbbell with the index flat against the head and get into the positon of the video and do a hold (think about lifting it with your pinkie knuckle). If I straigthen the arm, I feel that at the origin on the carpi extensor ulnaris. You can position your arm to parallel with you torso grab the weight like in the video, and bring the weight into complete radial deviation/extension (think about lifting with your index knuckle). When I do that, I feel it at the origin of the carpi exensor radialis longus. I just started experimenting with last two however, so those observations are from my first time with them on Monday.
I have some flexion holds which are fun too, but I'm not working on them right now. Important side note: this lift puts alot of shear stress on the bones, and getting good at it is partially determined by your ability to alow for and withstand that. I take my bone strength up with the flexion holds, that way I know the only limiting factor on the extension hold is wrist and tendon strength.
Carter: Have you tried that with a lever bar (Heavy Hammer, etc.)? Maybe a combination of timed hold with your exercise and a timed lever hold would be effective?
I have standard dumbbells which I offloaded like a really short sledge hammer. I got to 40 lbs for ten seconds for a lift simlar to slim's behind the back hammer lift from the floor. I put that down though, I didn't feel like it was helping because I started straining my carpi extensor ulnaris tendon at the insertion on the side closer to the ring finger as opposed to the outside where that lift pulls the hardest (on the right arm of mainly--that's the one that gives me the most problems). I have also done a strict vertical lever with a 12 lb sledge hammer--I really want to do a 16, but I have a long way to go.