I find lunges really difficult, because my palms don't reach the floor when my breasts are being mashed into my knees. They also get in the way when I try to hop to the top of my mat from down dog. Am I just doing it wrong?
I'm a 32DD, and I've found that you have to try a lot of sports bras to get one that works. The best running bra for me, the Enell, is awful for yoga, mashing my boobs together, choking me in shoulderstand, and restricting my rib cage when I'm trying to breathe.
The advice isn't bad about a sturdy bra, but as a fellow busty girl, it needs to be more specific. And there is NO WAY I can wear a strappy top without a bra, unless I want to flash the entire class--not nearly enough support for the style I practice.
You need a bra that compresses AND seperates. This prevents the breasts from getting mushed together, which is causing the difficulty breathing. Try Title Nine. My favorite so far is this one: http://www.titlenine.com/product/bounce/dd-cup-bras/310125.do?sortby=ourPicks. It works so well that I have it in three colors.
I have found that tightening a yoga strap over my breast (binding them downward) helps with breathing. Also, a looser sports bra helps by allowing my chin to rest between my breast. I will be trying the suggestion of focusing on lifting my rib cage the next time.
oddly enough, i find that Yoga is the only physical activity NOT BEST SERVED BY A SPORT BRA. Indeed, a "sturdy" or sport bra tends to center the breasts in the same alignment as the chin and stomach, increase duress :)
i find that a simple spaghetti strap top is more efficient at letting the breasts spread laterally, especially in shoulder stand, allowing me a scant couple of breathing inches.