I have had this problem several times when I've gotten through doing a long bike ride. I don't feel short of breath, am not wheezing or anything, but if I talk after riding, I get so that I can't breathe. I have pulmonary hypertension. If I don't talk, I'm fine, but once I start talking, I absolutely can't get enough air. Feel like I've held my breath way too long and can't get enough air in. Is this the pulmonary hypertension?