• Consequences of the Breathing styles, from a medical student's perspective •
When they re used for too long or too intensely, each tehnique has certain effects on the user, that must be overcome or treated after a gruesome battle.
-Water Breathing - channeling the energy for Water breathing rarely affects the user , but it can bring the body temperature too low after prolonged use. The user will feel their fingertips freeze first, then it will affect their movement as they re basically freezing from the inside out. Water Breathing and its derivates (Ice Breathing) naturally use lower body temperatures. The user must be trained to withstand the low body temperature, artery contraction and the temporary high blood pressure that comes with it. Their muscles are also trained to support poor vascularization because of the body's response to cold - vasoconstriction. A skilled Water Breathing user will instinctively train their lungs to be able to function under cold temperatures since the cold air / low body temperature will trigger, in worst case scenarios, the state of shock. Such happens, as we know, when Giyuu uses the eleventh form - Dead Calm, his heart temporarily stops , regaining function only because of Giyuu's training and exceptional physical state.
-Flame Breathing : opposed to Water Breathing, the user might overheat, and the effect takes place faster than other tehniques. With a higher body temperature, the Rengoku family usually tolerates it well, but it can affect them too after using it too long or too intensely. The user must be trained to withstand the higher temperature, higher heartbeat and vasovagal reactions that take place - artery dilation and, if it gets to their cerebral vascularisation, passing out (because of the poor circulation to the brain). Aside from the functional reflexes of the body, the high temperatures , used especially by powerful Flame Breathing users will affect the fluid quantity of the body, the first affected being the nasal secretions (that help us breathe and humidify the air) and the saliva and mucus that coats the pharynx - making it harder to breathe altogether. The Ninth Form - Rengoku (Purgatory) is a form that only the Rengoku family can survive , and even then , they use it as a last resort because they know / expect they will die anyway. (as we saw in Rengoku's fight against Akaza.)
-Thunder Breathing (lightning breathing) - the effects take place fast too, and if the person is not trained or has a lower tolerance for it, it might get fatal pretty fast. The high electric currents that the technique triggers will mess with the heart first, its function relying almost completely on its own electrical function. If the Tehnique tampers with the heart Sinoatrial Node's electrical function, it will trigger potentially fatal arrythmias, that will lead to either cardiac arrest, or fibrilation. The user must be trained to withstand the currents that affect their heart muscle, that will further affect the circulation and life long risk of cardiac arrest. The second organ that will get messed up by the tehnique is the brain, the electrical currents potentially tampering with the transmission of synapses between neurons - which will lead to either passing out or a temporary state of delirium / coma. This only happens after long , intense battles in which the Slayer has overused their Thunder Breathing. Aside from that, the local and immediate effect the tehnique can have on the body is muscle spasms (especially in the legs and arms) , triggered by the non-specific electrical currents that activate the neuromuscular synapses indefinitely (it passes after the receptors have a negative feedback that lowers their sensitivity and number).
part 2 - Sun Breathing
