My knuckles were at one point fairly pointy, with deep valleys between them. I noticed after a while that the first two knuckles (where I generally strike with) have flattened out slightly. I can even notice a change between a soft fist and a slightly more clenched fist - I can visibly see the knuckles slightly roll outwards to form an even flatter surface.

Is this normal and as I continue how should I expect my fist to change?

There is no pain or anything like that, just an interesting change I've noticed.

EDIT: Because I'm seeing a lot of people talking about bone reshaping I want to point out that this change is not intentional, it's just what I've noticed. There are currently no known medical implications. It's more of a curiosity in whether or not this was common and how it might continue to change in the future.

6 Answers 6


The fist, like the rest of your body, adapts to the demands under which it's placed. The difference in the valley between the knuckles of the fore- and middle-fingers is likely not due to a remodeling of the bone structure of those joints, but rather is likely a change in the development of the muscles of the hand under demands of the grip, causing those two knuckles to flex slightly further apart. This is completely normal.

Unless you're punching against concrete walls, human skulls, or trees with regularity, bone remodeling is not likely to occur - proper strikes against even heavy bags are not resisted enough to cause significant fracturing and calcification.

From a personal level, atemi no tanren training resulted in building the muscles in my hand significantly, which now looks a bit like a squished toad on the end of my arm. This is purely the result of the muscles building especially in my dominant hand.

If you are at all concerned that any sort of training you're doing is leading to any sort of detrimental result, you should consult a doctor. An x-ray of your hand will show signs of remodeling and calcification that might lead to repetitive stress injuries or arthritis due to inflammation and remodeling of the joints.


Calluses (skin growth)

After many years of hand conditioning (punching makiwara and doing knuckle press ups) karateka can develop calluses on their dominant knuckles, such as these from Dan Djurdjevic's essay on conditioning:

callused knuckles from makiwara training and knuckle press ups

Another example of callused knuckles from the Big Stick Combat Blog:

enter image description here

Cortical remodelling (bone adaptation)

Wolff's law states that bones adapt to the loads they're placed under. The bones in the hand can remodel themselves to become denser and change shape when subject to repeated load.

A study into the effect of lifetime loading on bone density (available here) supports the idea that prolonged loading leads to denser bones:

In conclusion, a greater lifetime loading history was associated with region-specific adaptations in cortical bone density.

The U.S. Department of Health's website offers a lot more information on the effects of exercise on bone density. Interestingly, they suggest that bone density will decrease if you stop conditioning.

There are some examples of training regimes to build bone density on Sihing Paul Wang's site.

Broken knuckles

These typically appear sunken (not pronounced, as you describe in your question). You can reduce the chance of broken knuckles by aiming for soft targets and using open-handed strikes.

Broken or sprained wrists

Caused by misalignment. It's very important to punch with a straight fist: the back of the hand should lie flat with the arm; there should be no 'ramp' where the hand begins.


I had a friend who was a large, strong man who radically reshaped his hand over several years of punching wooden dummies without wraps, displacing the first two knuckles back to an unpleasant and less-functional position.

More seriously, training a lot of punching without wraps can ruin your technique. If you start tightening the fist too much in preparation for impact, that's training you to tighten up and can reduce your speed and power delivery.

My own painful lesson in over-conditioning was from doing too many fingertip pushups. I worked my way up to 50 per day over a period of about a year and then within another year had developed stress fractures in the bones in the back of my hand.


In short term the pain tolerance will increase and the ability to hit harder will also increase but In long term expect problems with your hands, shakes, floating pices of cartride in your knuckles etc. .

Hands are not meant to be used as hammers, intelligent beings use hammers instead.


Depending on the surfaces your striking and with what protection your using, i.e. gloves or wraps, you can to modify your knuckles. In practice called Bone Remodeling, placing stress on your bones over long periods of time you can develop micro 'stress' fractures that get filled in with calcium, this modifies the bone itself and might be noticeable where the bone can be clearly visible through skin, i.e. knuckles and elbows.

You might also be developing calluses and/or thicker skin in those areas due to repeated stress. Additionally you have muscles in between your knuckles that can be growing larger and modifying your normal bone alignment slightly.

I recommend using at least wraps when punching as you can develop RSI injuries to the knuckles.


Definitely don't try to rush bone conditioning. It is a slow development that happens over years of training martial arts. It's also a good idea to make sure your diet has plenty of calcium in it (dark greens have lots of calcium, don't just chug gallons of milk.)

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