I fixed the Colorado University study link. As far as the WSJ article - unfortunately I don't have a good source on breathing exercises without the training dev

I fixed the Colorado University study link. As far as the WSJ article - unfortunately I don't have a good source on breathing exercises without the training device. Hopefully someone else can help. All of these things are somewhat speculative. Imo, worth doing, but don't trust anyone who says it's 100% proven science.