I just responded to a question/problem with gasping for air, posted on the Clarinet Bboard on www.woodwind.org.
To my knowledge, I have never had trouble with breath support or with air speed. I think my tone is decent and full, and I can play fff easily when required. ... I have plenty of air to honk through my new toy...a bass clarinet.
Yet, on my soprano Bb, I often feel like I am gasping for breath. Or perhaps a better description is that I feel like I may take in too much air and it doesn't all get used. It's like when you hold your breath for a long time without exhaling.
Therefore, while it seems natural to refill the lungs at the end of a phrase, I feel the need to take an exhalation break as well, although there is often not time for this. When there are a few measures rest, I find myself breathing rather rapidly until I have the sense that I have gotten back into a regular breathing pattern. It worsens in solo performance, when the nerves kick in.
Is there such a thing as breathing too deeply before playing? Is there a way to get rid of extra air without sacrificing dynamics or tone? My deep breathing happens involuntarily, and when I consciously think about taking in less air, I start to feel oxygen-deprived, and require another deep breath. Am I just full of hot air?
After years of exploration into this problem, which I also suffered from, I have found the solution. It's simple to describe, but can be tricky to enact.
The problem occurs not so much because you have too much air, but because your breathing apparatus literally goes into an anxious panic from being constricted and tight. If I may, I recommend you think about it as a problem of quality of air and exhale, rather than too much air. (of course, the previous advice not to over-inhale is absolutely valid)
There are two parts to the process of breathing and supporting with quality. 1- quality of inhale and 2- quality of exhale. Both are important, and related to each other.
1- The inhale should be a soft (quiet) but quick expansion of ribs and simultaneous dropping of diaphragm/gut. The shoulders go up, but only riding the ribs, which expand out in all directions. The gut "fills" as the diaphragm pushes down. Think of creating space for air, not sucking air in. This process allows your breathing muscles to stay soft and open.
Do not hold the air before playing. The inhale and exhale should be like going over the top of a roller coaster hill, just a change of direction, not stopping. This is key to prevent "clutching" of ribs.
One critical fact: The diaphragm can only pull down and create inhale. It is a one way muscle. It cannot "push" air out. The phrase "diaphragm support" is misleading and incorrect. The only action of the diaphragm during exhale is its strong tendency to return to resting position, going up. Keep this in mind!! However, the muscles around the abdomen DO help with exhales and can be supportive in controlling air release. Knowing what is what helps to better master the process.
2- The quality of exhale is equally important to attaining flexible support. When nerves kick in, your body tends to tighten, especially your neck and shoulders. The rib cage can go along with this tension, resulting in "constriction" instead of "support".
Keep your air free and flowing while playing. To practice keeping the air free when playing, try "sighing" through the instrument several times without playing. Relax everything as you exhale, with a little squeezing from the whole gut at the end. Keep neck, throat and chest "light". Now play a few notes using the same sighing exhalation. Slow this exhale down carefully to the point where you can play a fairly long note. Ultimately, "support" is a delicate, slow "letting" release of air, not a severe pushing. Volume of sound is increased by quantity of air, not by constriction of ribs.
As you play, be aware of the possibility/feeling of a fresh inhale, as a reminder of the soft opening of the space in your lungs. This helps keep the ribs "alive" and tender, rather than constricted and closed. (I got this idea from Tony Pay's article on support. See link below)
At some point, you may literally feel a soft squeezing around your heart, from your whole torso, all directions, top to bottom, as if your torso is gently enclosing the area around your heart. Don't seek this out as a goal; it's just a description of a feeling which lets you know your are on the right track.
The gist of my lecture is to monitor and prevent any "constriction" at any time, whether on quality of inhale or exhale.
I also strongly recommend that you refer to Tony Pay's long, but extremely informative and thoughtful article on breath support. I have learned a great deal from considering his ideas. (as long as you don't let your neck or rib cage constrict- have I said that enough times?)
Best wishes with your breathing. I hope it improves for you. I know that awful feeling of gasping for air during a delicate place in a performance!!