Does finger strengthening really destroy your manual dexterity? How bad is this? May it become a noticeable problem before you develop those Okinawan nail-like fingers? My interphalangeal thumb joint on my right hand no longer operates smoothly, at least not always. And I've been doing fingertip pushup(s) for quite a while (I tried to google a picture for you, but they all do it differently: they lean on the balls, not the tips of their fingers). Now I wonder whether the two are connected. They may not be since it's not the only joint I have a problem with (some of them occasionally make stupid grandpa-like sounds even though I'm 26)
There are generally two types of finger strengthening exercises: impact and grip. Impact exercises risk damaging the cartilage of finger joints, and over time that can lead to arthritis. Grip strengthening does not result in damage, and so it should be safe.
One example of an impact based finger strengthening exercise done in martial arts is thrusting your fingers into sand, dried rice, dried peas, pebbles, and then rocks. When I was in my teens, I mimicked what I saw in kung-fu movies. I got myself a big bucket and filled it with sand. Then I practiced thrusting my fingers straight down into the sand. This, I thought, would make my fingers strong enough to penetrate flesh.
Well, the only thing I accomplished by doing the sand bucket finger thrusts was to cause my fingers to bleed. My nail cuticles pulled back and ripped during the first day of this. I would go on to practice this exercise about 5 or 10 minutes every other day for a few weeks, and it did make my fingers much stronger. But I could see that it was going to cause my finger nails to come off over time and possibly do permanent harm to my nail cuticles. The strength that I gained from this wore off within 2-3 weeks after stopping. And there was no permanent damage to my finger nails as far as I could tell. I did get some changes in the smoothness of the nails, with slightly raised vertical lines appearing in them where there were none before. There was no change in overall nail thickness that I could see. But then, this experiment was pretty short.
Another type of impact based martial arts finger strengthening exercise involves using a target such as a makiwara or a punching bag. Or you can use a solid target like a board either on a wall, on the floor, or dangling from a string. You hold your fingers fully extended out in a spear-hand formation and begin making taps to the object, gradually increasing force over many weeks.
A variation of this will put a slight arch in the hand and fingers, rather than keeping the fingers fully extended out. That's done to make sure that you don't break your fingers upon impact. But instead of doing a spear-hand thrust with it like this (palm facing to the side), you would hold your hand palm facing down, and this is typically to attack the throat or the eyes. It's a trademark of Uechi-ryu karate.
You can see this in the strike to the eyes seen here in this video at 7:52:
Notice how the palm is facing down, and there's a bend in the hand and fingers. The fingers are not fully extended and straight out. That's because you don't want to break your fingers when you attack the eyes. There are a lot of bones in the face that will wreck your fingers if you do that.
You're not only strengthening your fingers doing this kind of finger toughening exercise, you're trying to figure out where your limits are. If you know how hard you can strike, when it comes to using it in a real life self-defense / fighting situation, you won't break your fingers attempting it. At least so the theory goes. In real life situations, adrenaline can surge, and it's hard controlling how hard you strike.
There are a lot of variations of this exercise tapping / striking objects with finger tips. As I already mentioned, you can arch your fingers or keep them out straight. You can try using a tiger claw and swiping from the sides instead of thrusting straight into the object. You can try using knuckles instead of finger tips, such as the leopard fist, dragon fist, or phoenix eye fist. You can use the thumb by itself. There's the crane's neck strike with the top of the wrist. Etc.
But know that each of these impact based exercises can damage the finger joints. Joints between bones all have cartilage to make sure the bones slide back and forth easily and without pain. If the cartilage is damaged, then the bones can touch and grind up against one another. It can cause extreme levels of pain and swelling. That's called arthritis. Before that even happens, inflammation can occur, which can be painful and can limit movement of the joint.
Your body's joints are actually pretty fragile. And damage to them never gets repaired by your body over time. So the damage accumulates. It can be a small tear that eventually becomes a big tear over time. Chunks of cartilage can actually get ripped off and float around in the joint. If enough cartilage gets ripped off, the bone itself can become exposed, and that's really bad.
There's no medical procedure that fixes this cartilage. Doctors will typically prescribe joint pain medication first. If that doesn't help, they'll go in surgically to clean up the cartilage tear, removing the flap of cartilage that's causing the problems. There are synthetic gels that can be injected to act as a kind of cartilage replacement, but it eventually disappears. And lastly, there are complete joint replacements that can be done (chopping the joint off at the bone and replacing it with metal and plastic), but I'm not sure if they typically do that with finger joints. It's usually done on knee and hip joints. Joint replacement may not give you back your full range of motion and may mean you can not do martial arts techniques with that hand ever again.
As you get older, this accumulated damage to the joints begins to limit what you can do. You begin to move differently, because immense pain will occur. And if you fight your joints and force them to move in a way that causes you pain, those joints will lock up on you out of your conscious control, and you will be unable to move them at all for a time after that, until the inflammation calms down.
Finger joints are some of the most fragile joints in the body. And the fingers are important in so many aspects of your life. They're used for writing and working on the computer. If you're an artist, you need them to be finely tuned. If you're working with your hands on a daily basis, like a plumber or a mechanic, they need to flex and take heavy loads. Keeping your finger joints healthy over the course of your life is extremely important.
Therefore, I caution anyone who is attempting to do these finger impact conditioning exercises to make sure you're not damaging the cartilage. That means you need to go light and slow at first. The second you feel any pain, stop, and don't return to the exercises until at least a few days have passed.
Or better yet, just don't even begin these kinds of exercises. If they're part of your martial art, and you feel you have to do what your teacher says, just go very light. Unfortunately, not all teachers will let you just say no and not do these exercises. That's a sign of distrust, and teachers just don't respond well to that. You're just supposed to obey as a student. They may say it's okay, that there's no harm involved in it. But there is harm. They're just not aware of it.
My advice is to talk with your teacher ahead of time and explain that you will have to go very gentle with the types of exercises that impact the fingers due to medical reasons. You can even talk with your doctor about it ahead of time, and your doctor will almost certainly tell you the same thing I just told you. That way, you won't be lying when you tell your teacher you have to go easy for medical reasons. And if your teacher then inquires further, tell him it's your doctor's orders. I think then most martial arts teachers will understand and won't feel disrespected by you when you refuse, nor will they try to pressure you into going harder.
There certainly are examples of 80+ year old karate masters who have these huge knuckles and who don't seem to have problems with arthritis. At least, they're not going to admit it, and it's not something that usually gets talked about out loud. But those people are the exceptions. Something like 99.99% of all martial arts students stop doing martial arts decades before they reach ages where you're going to see arthritis appear. The ones that remain active in martial arts are probably very different from most people and may have genetic advantages that others don't, or just happened to learn how to do it right without causing damage. I wouldn't think their results are typical.
Some of the slapping kinds of impact exercises, as opposed to the thrusting ones, are attempting to deaden the pain nerves in the finger tips. Those don't damage the cartilage. And so those should be fine. The nerve deadening is not permanent, so long as you're not overdoing it. I think it's rare that any permanent damage would occur in these cases. And the training wears off within 2-3 weeks.
Grip Strength Exercises:
Grip strength is a big part of finger strengthening. It's the muscles of the forearms that really matter for grip strength, because those are responsible for flexing the fingers. So to strengthen fingers, you're going to want to work on forearm strengthening exercises.
One example from karate is to use your fingers to grab a wide-mouth jar filled with water, sand, or stones. At first you start with nothing in the jars, and then work your way up to a completely filled jar. At first, you'll just raise them an inch off the ground, and then work up to being able to lift them all the way up until you're no longer crouched down. And if you go further, you can raise your arms up from the shoulders either towards your front or towards the sides. That works the shoulders and trapezius muscles as well as the forearms.
You can see this at 0:56 in the following video:
Another method of training finger strength in martial arts involves finger push-ups. There are many variations of this. You can attempt to arch your entire hand and fingers as if you placed a small bowl under each hand. That's a convex shape. Or you can allow your fingers to curve inwards in a concave shape, which seems easier to me but does increase the risk of joint injury.
Start on your knees if you can't do a full push-up, and then straighten your legs out later when ready. Then you can move on to using the thumb, index, and middle fingers only. Then get rid of your middle finger. Then only thumbs. Then repeat all of that by doing Archer style push-ups, leaning over one side more than the other. If you really advance, you can try handstand push-ups on your fingers. Look at calisthenic videos for tips on how to work up to a handstand push-up.
There are weight lifting exercises that emphasize forearms, such as the dead-lift and pull-up.
Dynamic tension is used in many martial arts, for example Goju Ryu karate's Sanchin kata. Using dynamic tension, you tighten your fist and forearms as much as possible, and then release. It's this tightening and releasing that works on grip strength, among other things.
Clearly, finger grip strength is a topic of some importance in many if not most martial arts. There are plenty of exercises I didn't mention. Martial arts are full of them. For example, in Chen style T'ai Chi, there's something called a bang. It's a "V" shaped piece of wood that you hold and practice gripping while bending your wrists. Other martial arts use ropes attached to pulleys and weights. There are rubber bands used in some martial arts. I've seen some using springs with finger holes at the end. Some use very long, heavy poles. Some use weights attached to the end of short sticks. Martial arts like Judo, BJJ, and Wrestling work on grip strength just by practicing on a partner, by grabbing a hold of their partner's gi, arms, legs, and neck.
As for whether or not these exercises hurt your finger joints at all or cause arthritis over time, my feeling at this time is that they're generally safe so long as you're not hyper-extending the finger joint by overloading it.
Where you can potentially harm your cartilage with grip strength exercises is if you're doing something like a concave finger push-up, and your joint gives out. In that case, you're overloading the joint, and then your entire weight causes the joint to bend inward and snap. If you do that, you can tear the cartilage in the joint, as well as the ligaments and tendons.
So when practicing grip exercises with the fingers, be careful not to overload them or cause them to hyper-extend. Work your way up to higher loads.
In conclusion, I do not recommend impact based finger strengthening as it can cause damage to joint cartilage over time. Instead, think about working on grip strength more than anything. With everything, be cautious not to overload the joint and gradually work up to higher loads.
Hope that helps.
This depends a lot on how you approach finger strengthening and yes, for most cases it does because it is done wrong.
As of impact training, just about everything important is said in Steve's answer.
I would like to add an important aspect on strengthening exercises in general which is very important for anything regarding the fingers in particular, no matter whether you choose jars, finger push-ups, grip trainers, weights and bars, or bouldering for that:
It takes about three times the time frame for your cartilage and ligaments to adjust to new training stimulus, compared to the muscles.
This means that while your muscles in the fingers may be able to cope with a lot of hard exercise already, you should be very careful not to overdo it, start with low loads, and only add load and reps slowly over weeks and months. This is especially important for the fingers as while they can support or hold your body weight if need be, they won't be used to it and the leverage and relative fragility of the passive mobility apparatus (bones, joints, ligaments, cartilage) make it prone to stress injury.
That being said, most of the damage in fingers that impede mobility are because of peak strain not because of steady conditioning so that any amount of things that can go wrong, especially muscular failure under full load and external peaks of force, should be avoided.