As can be seen from „Asthma The Biography“ by Mark Jackson of Exeter University England (on Google Books), the disease has meant the fateful and almost true believer quest for a causally acting medication This meant neglect of respiratory mechanisms for increasing the asthma-impaired lung inflation.
As recently demonstrated by Prof. Alison McConnell in England and Dr. Paltiel Weiner in Israel and many other scientists, inspiratory resistance is needed for adequate lung function. This might seem obvious owing to the association between asthma and mouth breathing (involving the absence of resistance on an inhale). The method recommended for combating asthma has been named “respiratory muscle training”, but Weiner states (http://chestjournal.chestpubs.org/content/102/5/1357.full.pdf)
“The main mechanism whereby hyperinflation adversely affects the inspiratory muscles is by forcing them to operate in an inefficient part of their force length relationship. Hyperinflation shortens the inspiratory muscles and diminishes their ability to generate negative pressure while inspiring It causes the flattening of the diaphragm, which in turn places it in a serious mechanical disadvantage, because it has to be curved upwards (according to Laplace's law) in order to be effective.
The axial direction of the diaphragmatic fibers is also lost by
They are directed medially or inward and have mainly expiratory action. The area of apposition between the costal fibers of the diaphragm and the inner rib cage becomes smaller, resulting in less effective rib cage expansion during inspiration.”
So the method might be pedantically termed “inspiratory muscle alignment training”. The devices such as “Powerbreathe” are calibrated so as to know what suction is being applied.
However a rough notion of the mechanism may be obtained by drawing in air through a stenosis defined by finger placed between one’s lips which perhaps a bit more natural than a device. It has the advantage of being able to increase suction toward the end of each inhale, but the experts recommend a device.
All this goes to show that classical approaches to asthma are a waste of time, but of course this is not “direct medical advice” from one’s doctor.. RF