I've read a lot about iron hand training on the internet, and there is heavily conflicting advice. I want to try to clear that up here, as I started iron hand training 3 weeks ago and I'm not sure if I should continue. I'll try to make my question as organized as possible.

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### What I currently do:

This is my daily routine, for **each hand**:

1. I punch downward into a bucket of sand with a closed fist so all my knuckles contact and dig into the sand, 300 times.
2. I strike [this canvas bag](https://rads.stackoverflow.com/amzn/click/com/B08K37NG79) (filled with sand) with my palm, backhand, blade, and fingertips, 200 times (for each part of the hand listed).
3. I strike [this concrete brick](https://www.homedepot.com/p/8-in-x-4-in-x-16-in-Concrete-Solid-Block-401500100/202524817) just like in step 2, but 100 times only.

The total number of strikes for all parts of the hand combined is 1500 strikes **per hand**, daily. I don't hit so hard that it hurts, just enough so it's uncomfortable. By the end, my hands are red, superficially scratched up, and slightly swollen, but NOT painful or bloody.

### Why do I train iron hand?

I stopped training martial arts (boxing and jiu jitsu) 2 years ago due to a serious heart condition, which I don't need to go into. Recently, I became very interested in the idea of toughening my hands so they don't hurt when I strike hard surfaces, and so I can break bricks with my bare hands. I also saw it as a way to get back into some form of martial arts training again. Also, on two separate occasions, someone tried to rob me but I was able to flee both times; I was lucky they weren't armed, but if I ever need to strike someone, iron hands would be useful. While I'm not a professional, I am serious about wanting to build tough hands.

### My concerns:

I play piano almost everyday, and my job requires me to type on a keyboard all day. I have read online that improper iron hand training, *or even proper training,* could cause nerve damage over time. My main concern is avoiding this nerve damage, obviously, and other such long-term injuries like arthritis. So far, after 3 weeks of iron hand training, I haven't noticed any deficiency in my piano or typing ability.

### Some of the sources I looked at:

##### Sources AGAINST iron hand:

* [Another SE answer claiming that as the surface of bones calcify, the bone underneath becomes more brittle, citing Wolff's Law.](https://martialarts.stackexchange.com/questions/8065/how-to-condition-knuckles/8075#8075)
* [Someone claiming iron fist gave them arthritis.](http://www.kungfumagazine.com/forum/archive/index.php/t-41712.html)

##### Sources FOR iron hand:

* [A suggested method that is similar to my routine, but not exactly (scroll to "The fourth method is called the slapping method...").](https://eastmeetswest.com/hands-like-stone-in-100-days/#:%7E:text=The%20fourth%20method,morning%20and%20evening.)
* [A (pretty long) forum post claiming that iron hand doesn't cause arthritis, and may prevent it, also citing Wolff's Law, and many other things.](https://www.martialartsplanet.com/threads/iron-conditioning-the-myth-buster-post-makiwara-iron-palm-iron-fist-breaking.58779/)

I know these sources aren't medical studies, but honestly, I couldn't find anything that academic on iron hand training. Mostly anecdotal stuff.

### My questions:

What is your advice about iron hand training? Based on what I've written here (and your knowledge), do you advise me to stop it? If not, do you think it's ok to continue my routine above or should I change my routine?