I recently found out during respirology tests that I have a condition known as Cirrhosis which is an auto immune condition that has led to scaring of my lungs, I suspect I had this for most of my adult life. The respirologist was surprised to learn that I have been an endurance athlete most of my adult life with respectable running times in the 15/32 for 5K and 10K and many Kona slots. I have always had lung symptoms which I attributed to exercise induced asthama.
The Dr recomended lung exercises as I have imparied lung tital volume and suggested using an inexpensive resistence device. I had thought that these devices were purely ineffective but he suggested not and directed me to the long term benefits of these devices. Here is one of the conclusions:
“There is good evidence that respiratory muscle training can improve exercise performance in healthy subjects, respiratory symptoms in some patient populations”.
Here is the study and a link to a favorable article by respected researchers Alex Hutchinson