I've been training my forearms or doing some form of grip work nearly daily for the past few weeks. I've put nearly an inch on the belly of my lower arm and my wrist is noticeably thicker (I didn't measure this prior since I didn't think it would increase). I've always been fascinated with having a strong grip, but I've only actively trained it for around 2 years off and on. I believe it is the weak link in many lifts for most people and it's generally the most helpful thing for real-life (probably tied with hinge motions like deads and swings).
Yes that is a real regular sized can and hand (Jeff Dabe)
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Your goddamn forearm is a microcosm: there are tons of little muscles in there that do all kinds of different shit. Just think of all the movements you can make with your wrist and fingers, then attempt to delineate each wrist motion with each finger position. That's a big ass number. So you need a broad ass training regime. My personal grip work consists of 9 movements over 5 days (2 moves a day, one is repeated since it's a restorative movement). It sounds like a lot of work but it really isn't. 1-3 working sets for 2 moves after your workout is a drop in the bucket compared to the benefits. Now before I go on, I do a lot of fat grip (open hand grip) training in my regular workout so that is not included in the grip routine, nor is any type of closed hand hold (support grip) like farmers walks or deadlifts since I do both of those 2-3 times a week. All these movements are forearm and hand specific.
Levan Saginashvili is a man of many skills (RIP Melon)
So here is a general list of movements that you could potentially train when doing forearm and grip work.
Wrist Flexion: think regular wrist curls
Wrist Extension: think reverse wrist curls
Finger Expansion: opening your hand against rubber bands around your fingers. ALWAYS DO THIS, your elbows will thank you.
Ulnar Deviation: your pinkie moving closer to your forearm like swinging a hammer.
Radial Deviation: your thumb moving closer to your forearm like a hammer curl
Supination: turning your hand palm up like when you curl to get a good contraction or tightening a screw (right-handed)
Pronation: turning your hand palm down like loosening a screw (right-handed)
Crimped Hand: think climber hang board type stuff, only using fingers
Open Hand: pulling where your hand doesn't fit all the way around the bar like using fat grips
Pinching: fingers and thumb only, I call this the cheeseburger grip
Supporting: any pulling you do with your hand totally around a bar like pull ups or deadlifts
Crushing: think those hand gripper things were you curl your fingers to your thumb
Now I know there are some overlapping movements and yada yada yada. I'm just giving y'all the advanced basics I guess. Now I'll give you guys my split and my last cycles exercises as examples. I only do 1-3 working sets per exercise along with 1-2 light warm ups. I keep the volume low so I can hit it damn near every day of the week without any loss in strength. The motion is first followed by the move I recently used in parentheses:
Wrist Extension (reverse barbell curl)
Supination (judo belt supination)
Radial Deviation (hammer curl top partials)
Finger Expansion (rubber band expand)
Wrist Flexion (fat grip wrist curl)
Pronation (judo belt pronation)
Pinching (pinch block holds)
Ulnar Deviation (sledgehammer lever)
Crimped Hand (rafter pullup)
Finger Expansion (rubber band expand)
Loading is relative to the exercise. You can move a shit ton of weight on hammer curl top partials if you want (sets of 3-5 reps), but not nearly as much on pronation and supination moves (I use sets of 10-20 on these). Keep in mind to ALWAYS use high high reps for Finger Expansion. I'll do sets of 100 reps with a rubber band or two wrapped around my fingers. If you don't know what these movements are, Voice of Armwrestling and Jedd Johnson on YouTube are really good resources for descriptions and instructional videos. If you do a sport, like powerlifting or BJJ, think about the ways you use your hands and train those grip modalities the hardest then pick up some other stuff to balance things out. For example in judo, crimped hand and radial deviation are important for grabbing and off balancing people in the gi; and in Strongman, open hand and support grip would probably be your modalities since you deal with axles and lots of holding. Give this a try, maybe build your own routine, and share your workouts with others. This year fuckers have been pulling us around; closing gyms, quarantining us, rationing food. I say its high fucking time we dig our fingers in yank back.
Image of yours truly mid pinch