There are a few exercises I strongly recommend for lower arm strength for grappling:
- Sledgehammer levering (Jedd Johnson Beginner Grip Training with Hammers)
- Pull-ups or chin-ups, especially gi pull-ups (inverted rows if you can’t do chin-ups)
- Brachiation (Dewey Nelson Basics, Tykato Basics 1-3, Tykato Basics 4-6)
- Weighted Hangs (What Tykato shows for hangs, add a belt and some weights)
- Hand grippers
- Extension bands
The reality is, we do a lot of gripping, especially in the gi. Lower arm strength (fingers, hand, wrist, forearm), not only in the muscles but also in the tendons can be a huge boon. This shouldn’t replace learning how to grip properly or that you should be comfortable death gripping for 5 minutes. More strength tends to mean fewer injuries. Will your grips be harder to break? Absolutely, but that’s a terrific side effect as opposed to an explicit goal if I’m being honest.
There are plenty of other lower arm exercises like hammer curls, wrist rollers, using fat grip adapters, holding/lifting with hubs, the list goes on. Those things can be a lot of fun and you can find great advice for them on r/griptraining if it’s a hobby you’re looking to pursue, but I think the above is a reasonable list of things to work on for grappling. Ultimately it comes down to some form of pulling/hanging/brachiating, levering, grippers, and extension bands. Four exercises that can easily be added to your workout or done on rest days to help make your lower arms healthier and stronger.