I work in Game Operations for an NBA team. During game days we constantly have to communicate on personal radio headsets which makes me very anxious sometimes. We also have weekly meetings with the whole department where we have to speak to the entire group. Can't tell you how fast my heart beats while I wait for it to come to me. However, usually a good deep breath and not holding it in while speaking gets me through it pretty well. It's weird, some days I wake up and I'm fluent while other days communicating is a struggle. I've found that it's worse with less sleep but even that is inconsistent.