What is the doctrinal justification for Shaolin martial arts?

It is [known](https://en.wikipedia.org/wiki/Shaolin_Monastery) that Shaolin monks practice a form of [Chan Buddhism](https://en.wikipedia.org/wiki/Chan_Buddhism) . It is also [known](https://en.wikipedia.org/wiki/Shaolin_Kung_Fu) that they practice their own form of martial arts. * What is the doctrinal justification for their practice of martial arts? * Additionally/alternatively, within the Shaolin view of Buddhism, are martial arts purported to have soteriological effect? * Lastly, as a bonus, are there any academic studies exploring the Shaolin doctrines? I found [an answer](https://buddhism.stackexchange.com/questions/9246/buddhist-shaolin-monks-and-their-practice) regarding their practices in general, but not about the doctrinal basis. Thanks.