I watched a couple of this guys videos. Some of them are interesting. He does isometric and tension exercises from what I've seen. Anyhow, here's one where he talks about the diaphram. He calls this isometric breathing but I think it's pretty much the Vacuum.
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Health, Fitness, Non-Apparatus Exercise, Unarmed Self-Defense, Firearms Self Defense
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Jarrell is an awesome kid his knowledge of isometrics helped me out alot when I facebooked him when I started out, he is a student of Batman O'briens.