Why measure exhaling by an exaggerated forced 1 second? If I do breathing at my normal speed, the deep breath in and back out feels smooth and good. I bet it is then normal or mild rather than obstructed. Why isn't breathing for 2 or 3 seconds good enough? If you maintain that, it seems good to me. No one breaths in a maximum forced pace. I think the normal speed should be part of the test, what your breathing really is like in your reality day to day.
Like the air diffusion DLCO. If my oximeter is consistently 96-98, I'm getting my oxygen, isn't maintaining that the goal? And good enough. These values seem in conflict.