Whatever the technique is, after all it is to do abdominal breathing exercise sloooowly. So you cannot expect any magical or miracle effect.
Let's awake to the realities.
However, my friend the physician says that continuous daily deep breathing exercise, ten to fifteen times per set, one set in the morning and one in the evening, can improve your health better than overdoing exercises (i.e. sports). Deep breathing exercise will enhance the function of the heart and lungs and prevent functional decline. So you mustn't make light of its effect.
Most of you may have experienced that your breathing is shallow and fast when you are sick.
And old people's breathing is shallow and fast, unless they do something special exercise or whatever to prevent fictional decline.
The fundamental of most breathing method is to do the opposite of what old and sick people would do.
The Shinto breathing method which is called "Ibuki-Nagayo no Den" is also to do abdominal breathing exercise sloooowly, exhaling completely letting out "Ha!", a sound which has a power.
Yoga breathing methods are also all basically alike. Those are variations of abdominal breathing exercises based on complete exhalation.
Besides improving circulation of oxygen and carbon dioxide, the exercise of inhaling deeply and exhaling completely focusing attention on Tanden will effect on inner organs; the movement of the diaphragm and abdominal muscles will stimulate (massage) inner organs.
When the inner organs are pressed and massaged with the diaphragm and abdominal muscles, blood and lymph and nerves are also stimulated, and oxygen will be happily delivered to every corner of body.
Some Yoga methods therefore has developed extreme variations such as holding breath too long or moving abdominal muscles too extremely that it looks like doing it simply to showing off their abdominal muscles. Those methods are indifferent to me so I don't comment about it here.
Anyway, as you know, all those Ki energy related exercises such as Yoga and Kiko (Tai Chi/Qigong/Chi Kung) and meditation and Zen meditation and Shinto and so on place great importance on breathing method especially abdominal breathing method.
That is because when you take a breath, especially when you exhale, a lot of Ki energy will be produced.
A slow exhalation will relax your body, open the capillaries in your whole body, improve the circulation of the blood, and Ki energy will be produced.
It is often said that if you get nervous, take a deep breath and relax. It is because when you take a deep breath and exhale completely, it will relax your body and open the capillaries, and blood rushed to the head comes down consequently.
There are several other ways such as Sanko Ikkyu, exhaling three times, i.e. one short, one short, one long like "ha ha haaaaa" and inhaling one time. When you breathe out vigorously like "ha ha haaaaa", it shakes inner organs and improve the circulation of the blood in inner organs. However, a slow gentle exhalation will relax the body more effectively than vigorous ones do.
And when the body relaxed and the circulation of the blood is improved, plenty of Ki energy will be produced naturally.