Please, first read intermittent hypoxic training, high mounting training, hypoxia and PULMONARY OBSTRUCTIVE DISEASE in wikipedia.
I claim that pranayama is intermittent hypoxic training that leads to mitochondrial hormensis. It includes inhalation, RETAINING of breath, exhalation with GRADUAL increasing of the RETAINING of breath that is self-induced suffocation (hypoxia) leading to increasing of mitochondrial matrix.
It improves longevity and endurance. On one hand, it decreases metabolic rate at REST (longevity) but on the other increase VO2 MAX while exercising. Thus, it reduces ROS at rest. I do not recommend you exert yourself aerobically to VO2 MAX.
My personal experience with pranayama is:
1.At rest, if I am not hungry I do not feel my breath, so need less oxygen (low metabolism at rest).
2.While exercising, I feel boost of energy and easily burn fat tissue.
All this with a couple of weeks practice.
Later on, I will provide information about physiological changes in the NERVE tissues, which are the most susceptible to suffocation (hypoxia).
At the end I will show easy (not time consuming exercise) that can be done in front of you computer or while watching TV.