Heh, that was the first symptom that got me on my very long road to diagnosis. I would cough after strenuous exercise and sex. But that was it. I didn't smoke or engage in anything that should cause a cough, I was young, etc. Took a looong time before I finally saw a pulmonologist who could recognize bronchiectasis on a CT, which I apparently had already had for years at that point. Bronchiectasis, in relatively young people, is almost exclusively caused by cystic fibrosis, so that got the ball rolling on the long path to diagnosis.

Some doctors may not like to know that they are your second opinion or third opinion, but it kind of saved me continuing to go to different doctors.

Not to say that you have anything so serious. It's extremely unlikely that you do. In fact, the most common cause of a mysterious cough is post nasal drip, if I recall correctly. I just think that people are less aware of these sorts of possibilities than they ought to be. I literally laughed when my pulmonologist first suggested I might have CF.

Edit: to be a little more helpful, you might want to try something like an Aerobika flutter device and/or a nebulizer (you'd need a prescription). They're good for helping to clear out the lungs, and you don't need to have some sort of special condition to use them.

So, the team that I'm seeing at Brigham & Women's in Boston has a testing protocol called invasive cardiopulmonary exercise testing or iCPET, which involves putting a tube into a large vein in the neck, putting a heart catheterization through that, then putting a tube in an artery in the wrist. This allows monitoring and comparison of blood pressures inside the heart vs. outside the heart as well as comparison sampling of arterial blood vs. venous blood. In addition to this, they apply EKG heart monitoring and respiratory monitoring via a gadget you hold in your mouth and breathe through. With all this insanity in place, they put you on an exercise bike until you can't stand it anymore.

What they find on this test is a combination of two things. First, the pressures inside the ventricles of the heart do not increase in response to increased physical activity the way that they should. "Low ventricular filling pressure caused by preload failure." And second, the DEoxygenated blood returning to the heart has too much oxygen in it, indicating poor oxygen uptake on a cellular level, which they hypothesize is caused by mitochondrial problems.

The treatments include a drug called pyridostygmine, which increases acetylcholine neurotransmitter to increase autonomic nervous system response to physical activity (and therefore increase blood return to the heart). Or a drug called midodrine, which also supports blood pressure. Plus supplements to support mitochondrial function like CoQ10, creatine, and ALCAR.

I'm not cured and back to where I was prior to getting sick by any means, but I'm able to hold down a full time job, which prior to treatment I most definitely would not have been able to.