Wait, what? That goes against everything we've ever been taught as brass players! Let me explain. You know the feeling when you are performing and start to feel anxious? Your heart rate quickens and so does your pulse. Your breathing gets shallow and you start to take a lot of them. But somehow, you constantly feel out of breath. Here's what's happening:
Consider a normal breath under relaxed circumstances. You fill your lungs completely full of air, which is made up of slightly less than one-quarter oxygen and the rest nitrogen, carbon dioxide, and other gases. We'll call all that stuff carbon dioxide for now because that's what most people understand. While you are playing, your body uses most of the oxygen for, you know, staying alive. The carbon dioxide is mostly blown into your horn. Once you're out of air, you take another breath and the cycle repeats itself.
But here's what happens when you're nervous. Your heart rate quickens, causing all sorts of problems but most importantly, you take in extra breaths before you are fully out of air. So here's what we end up with. You take your first breath and your body uses the oxygen. You blow some of the carbon dioxide into your instrument. Then you take another breath, but this time you don't have your full lung capacity to work with because there's still some carbon dioxide left in there. Again, your body uses the oxygen, you blow some of the carbon dioxide into your instrument, and then take anther breath too soon. Now you have even less lung capacity to work with, and again, your body uses the oxygen. At this point, you have a lot of carbon dioxide built up in your lungs and less and less oxygen to work with. So you feel out of breath and continue taking too many breaths because your body is reporting that it's out of oxygen and panicking. This is a dangerous cycle when you are already nervous!
You're taking more breaths but getting less oxygen! So what are some solutions to this? First of all, the easy solution to deal with this situation when it happens to you:
BLOW ALL THE AIR OUT OF YOUR LUNGS
Find a spot in the music when you can exhale completely and take a fresh breath to re-oxygenate. Try this right now—blow all the air out of your lungs and take a nice big breath. Do you feel how it instantly gives you extra energy? This works pretty much all the time in performance.
Here's the way to avoid this problem in the first place:
PLAY WITH LOTS OF AIR SUPPORT AND LONG PHRASES
Most of us play with a weak and wimpy sound when we get nervous. Make sure to keep putting lots of relaxed air into your instrument. And even though your "fight or flight reflex" is telling you to take lots of extra breaths, save them for the ends of phrases, or when you're truly out of air. This requires some mental discipline but it can be practiced. Try running up and down the stairs a few times and then playing some long lyrical phrases when you're already out of breath. The feeling is remarkably similar to what you feel when you're experiencing performance anxiety!
These techniques won't completely cure nervous performing, but they will get you one step closer. Good luck, and let me know how this works for you!
-Alex