I'm looking for exercises to help maintain a grip on an opponent's gi while pulling them around. There are two elements to this: strength and endurance. Meaning, I want my grip to be hard to break but also not tire out too much when I'm holding on to it.
A good way to get gi / kimono specific grip training is sling your gi / kimono top around a pull up bar or a tree branch and use that to do any number of exercises, such as
There are plenty more, use your imagination, but using the gi top is a good way to condition your grip and fingers to get that killer death grip.
We did an exercise at my first Judo club that seemed to help with grip. We would hold our arms out directly in front of us and then alternate between making a grip and having our hands as open as possible. Basically, like gripping thin air, but repeatedly. A very simple exercise, but it seemed to help.
How many times we repeated was a measure of how many were attending the session that evening, because we'd stand in a circle, facing in, and everyone would do the exercise together, but someone would count to ten and then the next person would count to ten and so forth until we'd been around the circle at least once; twice if we had a low turnout.
Take a newspaper (remember them?) and page by page, crumple the paged from flat paper to the tightest ball you can make with one hand.
There are a couple of things that you can do to help.
Go hang from something
Basically either go outside and find something overhead or get a pullup bar and hang from it. You can make a progression out of this, going from a pullup bar to one-hand on a pullup bar to hanging from a rope. The basic idea is that if you want to improve your grip strength, grip something!
It also tends to be pretty easy to find things to hang from, making it something you can do throughout the day if your environment is conducive to it.
If you are looking for a program, Convict Conditioning 2 has one that incorporates progressively more difficult variations of this and also recommends fingertip pushups. My standard disclaimer on CC applies: it tends to have great progressions, but ignore the marketing material.
Learn Massage (and other skills)
Trigger point massage is one of the things that has helped my overall grip strength a great deal. I started with Clair & Amber Davies's The Trigger Point Therapy Workbook, but really many if not most systems of massage will help tremendously here.
Here the big thing is to learn to work with your fingers, not your thumbs, but it does help grip strength if you practice regularly. Learning has the added benefit that you can treat a wide variety of muscular issues on yourself.
There are also other sports that strongly emphasize grip strength and it may helps to get a foundation in. I don't personally practice it, but an example here might be rock climbing.
Another thing I've had very good luck with is weapons training. Working with swords and short sticks (and probably any other weapon that you grip and has some mass), and particularly against a target, is a great way to build up hand strength, and is particularly useful for the "endurance" part.
The added advantage here is that it can usually be incorporated into your martial arts practice if your art uses weapons.
There are a few things you can do to improve grip strength. Like everything else, sport specific drills are best, training the closest to the actual activity your trying to improve.
on that note:
Your goal to increase your grip strength should focus on exercising your forearm muscles. There are several strength exercises and tools you can use to work out the different muscles in your your forearms.
Tennis Ball or Hand Grip
As @stslavik stated in his comment, you can grab a tennis ball and squeeze it to your heart's content. When squeezing the tennis ball, also hold the squeeze for a few seconds before releasing. As you improve, you can increase the number of repetitions you do. Additionally you can buy hand grip tools. These aren't terribly expensive things, but keep in mind you might reach an upper limit to the amount of strength training you can do with them once you reach a certain level.
Wrist Curls and Reverse Wrist Curls
A single barbell or a dumbbell in each hand will can suffice for this. You can do this while sitting and resting your arms on your legs. Anything that will support the weight of your forearms will work really.
Hold the barbell or dumbbell with your palms facing up and just roll your wrist towards you without lifting your arm and then release back down to a relaxed position. The reverse wrist curl is the same except your palms are facing down, and you roll your wrists backwards towards you. Here are pictures of what these two exercises look like:
You could also perform the wrist curls with your arm outstretched, but depending on what your level of ability is, you might end up working to keep your arms out more than working on your wrists. If weights aren't an option for you, consider using a resistance band instead (stand on one end and pull the other end up with your wrist).
Make Your Own Wrist Roller
A simple thing you can do is buy a plate or dumbbell, tie a rope through or around it and tie the other end to a bar or rod. Hold your hands out in front of you, and begin twisting the rod so that the rope wraps around the rod as the weight goes up. When the weight reaches the top, begin untwisting and let the weight go back to the ground. You can also choose to use different weights with it if you so desire. Here's an example of what it looks like from BodyBuilding.com:
That's the basic premise of one. If you don't have plate or barbell, you can improvise with using other materials like a gallon of water or a bag of rocks. You don't need a whole lot of weight to feel it as you curl the rope up or down. A broomstick would work just fine for holding onto as you train.
Buy a Wrist Roller
A SportGrips SideWinder is a simple device that is an extremely durable, small, and portable, and has adjustable tension which is controlled by a knob at the top. I wrote a blog post about this on the Fitness & Nutrition blog. It's simple and easy to use - adjust the tension, grab, and twist. It definitely helped me increase my grip strength over the last few months. The Sierra Mega Wrist Roller is also a similar product you can use. The only downside to these type of products are the cost if money is a concern, but you get what you pay for.
i've always liked getting a bucket or small garbage can and filling it full of uncooked rice. you can do what we call rice grabs by jamming your fist into the rice while grabbing and releasing handfuls of rice. cheap and effective.
Get Strong First
Mark Rippetoe has some words for people lacking general strength who want to increase strength in one particular area. From Jim Wendler's blog:
In other words, grip-specific training is barking up the wrong tree. Unless the student is already quite strong, the best way to develop grip strength is to work on general strength. Whole-body training will improve your grip strength faster than forearm-specific work, while giving you health benefits and strength for other movements as well.
General Training with a Focus on Grip
Keeping that in mind, what is the best way to tailor your general strength training to grip strength?
Once you can perform fifteen full-range-of-motion, no-kip gi-grip pull-ups, plus a double bodyweight deadlift, the student can add the awesome grip-specific training mentioned by others. Fat grips, oversize bars, wrist rollers, curls and other specialized training are very productive...once someone is strong enough everywhere else for it to matter.