how do i harden my knuckles?

One way is to do knuckle push-ups.

Hard knuckles will not make you a better martial artist though.

punch, punch, punch..start with something firm but not too hard and then work your way up in hardness gradually over time...a good start is a hard sand heavy bag/punching bag and that should last you for years, as your knuckles harden you can try tightly wrapping rope around a board made of strong wood that's about 4-6 inches wide, at least 2 inches thick (so it won't break easy) and maybe 8 feet long...bury it halfway in the ground with the rope tightly wrapped around the top to middle but make sure the rope doesn't overlap, it has to be flat against the board and each strand below one another...that will be your punching area. The rope will not only soften the blow a little it will also help your knuckles callus as it will wear on them and probably make them raw the 1st few times( i heard soaking your hands in vinegar is supposed to help after puching but i'm not sure). I know this sounds extreme but it works, i've seen a man who punches and kicks such a board daily to the point where his hands and feet are hard as a rock and the nerves are numb where he no longer feels the blows.

I've also seen a older chinese man who's been employing such techniques so long that now he punches a piece of steel hard everyday, needless to say his knuckles are huge and it looks like his punch will feel like getting hit with lead gloves.

FYI hard knuckles won't help you break boards any better, they'll just help you feel it less but if done right you shouldn't really feel the board anyway

its rather simple and self-explanatory...simply put, tap a surface/object(s) several times (100-500x) then massage thoroughly and apply some kind of muscle and skin liniment or ointment creme. The key word is TAP, it is rather stupid and uninformed when training for knuckle conditioning to slam your fists into hard objects...you may get the results faster, but in the long run you will come across painful arthiritis and loss of dexterity in your fingers = useless hands; clubs.

Use the 10% method as you do with stretching, there should only be slight pain (10%)...continue with the same impact force until no pain is felt, then increase the force.

As for the liniment, I would suggest some sort of Dit Da Jow (hitting wine) to treat the surface being conditioned. You can find it at any martial arts supply website (if you can actually find one now) lol. WWW.WLE.COM has some that I know for sure for a reasonable price. You can even look up how to make your own online...just do the research.

For the object or hitting surface, get a canvass bag and fill it with either fine grain sand (local Toys R Us carries that or home improvement store) or Mung Beans (which can be found at any asian market). The Mung beans are said to coat the hands/body part and also has beneficial effects on conditioning of the skin and muscles tissue.

Striking hard surfaces can deaden the nerves, but why damage your body in a negative way...the use of sand/punching bags prevents the deadening of nerves and any damage to the nerves in your hands for energy transfer, which is very important for what you are trying to accomplish. As with any weapon, if you cannot "feel it" it becomes a useless tool to be weilded by cavemen. The truely skillful use their weapons like the surgeon and his scalpal.

Good luck and be smart...Crawl (tap) before you can Walk (break) lol.

Proper technique is the best way to increase your punches effectiveness. Hand conditioning like you are talking about only leads arthritis. Making your hand or knuckles "harder" is unnecessary. The Makiwara or Maki is NOT for conditioning anything, it is for developing better technique, it should also only be used under supervision of a competent qualified instructor. Any conditioning that is required, will be accomplished through normal training and drills. Punching a wall is NOT Bright! Besides tearing up the wall you run the risk of breaking your hand if you hit one of the wall studs. Now there is a technique called Iron palm but it is almost impossible to find a qualified instructor and the training is prohibitively expensive.

You can harden your knuckles by punching a Makiwara stand.

Makiwaras are padded striking posts that originated in Okinawa for striking in Karate that are used to condition a person's fist to make the person's knuckles harder.

What you do is punch them repeatedly, and your nuckles will start to produce small microfractures, in time these microfractures will heal over and new more jagged bone will replace what was there, making your knuckles harder and more dangerous.

Also punching things like Makiwaras and trees, rock and and even beer bottles (as my friend once did in Kyokushin Karate) deadens the nerves in your hand so that you don't feel any pain from striking things.

In conclusion, striking things period can make your fists very powerful weapons. However, precision striking and technique are far more helpful in breaking boards in my opinion.

If you were thinking of taking a martial art that has knuckle hardening exercises, various forms of Okinawan karate, Shotokan and Kyokushin karate and some forms of Kung-fu all excel at fist conditioning.

Just hit a punching bag with gloves and wraps. Spar with gloves and wraps. Do knuckle push ups.

Don't condition your knuckles by hitting really hard stuff with no hand support. You are going to give yourself arthritis or some other kind of nerve damage, setting you back in training. Especially w/o supervision by a pro.

I would recommend very strongly that if you want to break concrete, train the knife edge or the palm heel. To condition the knuckles for board breaks, you can start hitting a bag filled with sand, not hard, and build up to some power, but not full out. After a year, you can change to steel sawdust or mung beans. Ultimately, you can change to a bag filled with iron shot or aquarium gravel.

For the palm heel and the knife edge, use an anvil or a granite block.

Keep in mind that it is very, very easy to break or damage a knuckle even by breaking one or two boards. The knife edge is safer.

You need to 1) lift weights, 2) condition the striking surfaces of your body, and 3) practice technique.

In breaking, there are three categories: power, speed, and creative. Decide which you want to master. For power, you'll focus on boards, patio blocks, bricks, and the like. For speed, you'll typically break with no holders (ie, without opposing force). And for creating breaking, you'll break different materials, or use flying or flipping kicks, etc.

Each category of breaking requires different conditioning for that part of the body striking the materials. You indicate you want to punch. Ok... that's not my first choice of striking method, but that's your perogative. I'm assuming you want power.

Begin by building muscle mass in the wrist, forearm, upper arm, and shoulder. Lifting weights is important, but you need to build explosive power, so, you need to do upper body plyometrics. Lifting weights (only) will not work - in fact, will hurt you. Clapping puships, etc, are good - but you need to research more upper body plyo exercises.

Conditioning... you need to start out light - don't go right into the hard stuff. Go to your local hardware store, buy a sandbag, lay it out flat across some stacked cinderblocks. Condition your hand by alternating: punch, backfist, ridgehand, knifehand, back-hand, palm, bear claw, and foreknuckle. Repeat 8 in any combination you feel comfortable for a single rep (so each rep = 8 strikes). Then do 50 reps. Don't do them hard, do them lightly. Do this each day for a few weeks. Then you can start practicing punching your hard materials. To do this, though, seek the advice of a good instructor - you will do permanent damage to your hands if you are not careful.

Technique... there's nothing like a good punching bag to help. Have a qualified partner on-hand to critique you. Don't just start wailing away at the bag, have each and every technique critiqued. Your partner should be looking at the whole package - your foot position, your hips, your shoulders, your arms, your wrist, your breathing, your facial expression: everything.

I would give a few months of rigorous, hard-core conditioning before starting to do power breaking with punch.

2x4? That means, against the grain. If this is what you want, you're asking advice that's out of my league. Few people in the world can do that.

1) punching blocks is for show mainly not a better martial artist

2) power comes from technique not hard knuckles

3) its a damn sure way to really screw up your hands in 99% of cases

4) last time i checked board breaking regularly wasn't a common martial arts practice in reputable places

if you really want your knuckles to harden punch dirt or sand, My Dad, who did Go Jo Ru, punch a bucket of sand everyday, and pounded on 2x4's until they were bent, I punch dirt and rocks because i dont have any sand at the moment, but wait for your hands to heal if they start to bleed, before you go out and do it again, best of luck