The quick inhale brings more oxygen in and sets off a flood of hormones that heighten our senses and help us respond quickly. "It helps us survive."Spending time re-learning how to breathe should become part of your speaker practice, and you may find you'll benefit by excusing yourself about 10 minutes before a speech (a handy stairwell or restroom will do for this) so you can get in some long, slow, calming and deep breaths. Want to see your physiology? NPR offers this link to a page about how the diaphragm works and to how respiration works and how it applies to performers (like speakers).
The trouble comes when chronic stress sets in. Under stress, a lot of interactions start to feel like near-collisions. "It becomes a part of us and we never release out of it," says Bilanchone. When we're stressed we may cheat the exhale or even hold our breath for moments. As adults, we can develop these bad habits that interfere with the natural rhythm of breath.
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When the Speaker Needs to Catch Her Breath (with relaxation response tips)