i've been binding for a while (like two-ish years), and have lost a fair amount of lung capacity as a result. does it return after getting top surgery, without having to do any specific exercises? or is it something you have to work at to recover, even if you're no longer binding?
It should return over time, because reduced lung capacity is tissue and muscle atrophy from physical restriction of your breathing. (If you constantly restrict your lungs, your body thinks okay, why should I bother maintaining any ability past this point if we never use it?) Gentle, consistent exercise will help—think about the difference in lung ability between your average layperson and someone who runs or hikes. This isn’t necessarily specific exercise, it’s just asking your body to adapt to the demands you place on it. A lot of people find yoga and deep stretching helpful; a lot of other people swear by massage. There isn’t a guaranteed method for recovering lung ability, and some people never fully recover from binding long-term, but being kind to your body while you ask it to recover will do a lot.