First of all, yes, labored breathing is an indicator that you are over working the heart. But if you are panting, or gasping you have gone too far. In other words it is not a very good indicator of over work because the heart has to be pumping too fast for a while before it effects the breath.
To extend the classic Chinese metaphor. The heart is the Emperor and the lungs are the Ministers. If the Emperor is acting inappropriately, the Ministers are likely to be indulgent for a while and they'll try dropping subtle hints before they run into court shouting.
But all of this misses the point that liver stagnation is rampant everywhere there is a booming service economy and cheep food! (For those of you who don't speak Traditional Chinese Medicine Lingoâ„¢, Couch Potatoismâ„¢ is the modern slang term for liver stagnation.) People with liver stagnation need to breath hard! They need vigor. They need to get their hearts pumping. They need to stimulate the liver to surge blood in and out of their limbs. They need to shout at something other than the TV set.
Another reason I didn't mention breathing in the previous post about the heart is that breathing practices are too strong and very hard to generalize about. I have two basic teachings about breathing: 1) Yin Proceeds Yang. 2) "Breath like the silk spinner and the jade carver."
Teaching about breathing is highly individual. If you have ever had an injury to your pelvis, shoulder, neck, ribs, or spine, there is a high probability that it changed your breathing. When injuries occur the breath immediately comes in to numb the area and increase blood flow. It is a bit of a mystery to me why these injuries linger so long in the way a person breathes, but they do. So teaching breathing is highly personal and esoteric.
In The Fundamentals of Pa Kua Chang by Park Bok Nam and Dan Miller they outline a systematic way of developing breathing. They start with one type of breathing and then move to another and then another. But they are very careful to point out that when you switch from one type of breathing to another has to be decided by a teacher who is monitoring your progress closely. In other words, the method can't really be systematized, it is esoteric.
In fact, over many years, unmonitored breathing practices can be harmful to the heart. I'm thinking particularly of taijiquan and yoga instructors who guide their students to breathe into the arms.
While I'm on a roll I should also point out that during intense exercise the muscles and the heart/brain compete for blood.Â Since the heart/brain is more important, your body will close off the perineum at the base of your pelvis in order to restrict circulation into the legs, and sometimes it will do the same thing at the armpits.Â You will know this has been happening to you if after exercising you feel all "tingly" in the limbs.