Is that the (sole) reason?  More than one martial arts trainer has told me that if you are definitely about to be involved in a fight -- and you can&#x27;t run away (number one preference) -- if you have a full bladder you should consciously empty it.  Wet trousers are far preferable to having your bladder rupture, so it&#x27;s a sensible pragmatic (or instinctive) action.  I&#x27;d imagine there&#x27;d be similar benefits in evacuating your bowels.