Hi I practice shorin-ryu ,when I decided to learn a goju-ryu kata naturally I chose Sonchin as a base kata later I read some articles about the danger of practicing sonchin because of dynamic tension breathing I ‘d like to know your opinion as a goju-ryu practitioners about following lines: Mark Bishop in his book “Okinawan karate” : “in order to harden the buttocks during the sanchin exercise , forceful closing of the anal sphincter is practiced .this ,I was assured will result in haemorrhoids after only two or three years of regular practice.” , in my copy of the book it says “haemorrhoids” which I think is “hemorrhoids” Thanks