Phi, in your discussion of reverse breathing you mentioned that it can lead to hypertension if done too often or strongly. Can you discuss what you mean by too often or too strongly a bit?
man! you had to ask that question! why couldn't you ask question like, when is the next party? and who bring the booze?
lets me see if i could throw on some layman stuffs. you can shoot me (with paintball) if i messed up. in the reverse breathing sequence, the inhale where you compress your abdominal while trying to pull in air to your lung. the only way to do that is to expand the upper chest cavity which stretches all the fasica and what not of your upper body which creates extra connectivity linkage between your arms and your body, so it would take the load off your shoulder (somewhat). because of the abdominal compression and upper chest cavity expansion, you create a higher pressure inside your trunk which acts as a big hand squeezing your middle from the inside. this compression squeezes your internal organs and all around your upper body, and force your heart to push blood through at a higher pressure than normal. your body defensive mechanism to deal with higher blood pressure than normal is to dilate all the blood vessels in your body, sort of increase the volume to decrease the pressure approach. you will notice when you do reverse breathing you feel like an expanding balloon. however, your blood vessels could only expand so far, after the max expansion, the pressure would build up. think of pumping air into a balloon then preventing the balloon from expanding. what you will have is pressure increase. so because the pressure increased dues to your heart trying to compensate for the compression, and your body trying to auto correct the situation, the pressure went up toward your head. when you do the reverse breathing hard enough, you will feel like your head ready to explode. also, because the reverse breathing won't allow air to fully pull inside your lung, you are sort of deprived your body of oxygen and increased CO2 level. you are sort of putting stress on your pulmonary system.
so that's a bunch of crappola information. the old admonition is that if you do it too hard and too often where your body hasn't the time to adapt, your "ki will leave you body and evil ghosts enter your body" (them asian have some interesting idea on what would happen to you, almost Halloween like). it's really a description for having a stroke. here is a question for you to consider, which route does your ki leaving you and the evil ghosts enter the same path?
ps. there is an interesting article on reverse breathing here http://www.dongs.com/thesis.pdf
. the article didn't mention his first name. hopefully, it was not "long".