Because our experiences are not universal and we don't question things that have always happened when we do stuff: it is not normal to taste blood in your mouth during cardiovascular exercise and if this is something that happens to you that you've never thought much about you may want to get checked for asthma.
To make a point:
Has exercising hard ever caused you to taste blood in your mouth without any kind of actual injury or bleeding?
Yes, I thought that was normal.
No, what the fuck?
See ResultsIt is not universal to asthma (so you can have asthma and have this not be a symptom) and it is not exclusive to asthma (it happens with other chronic illnesses and sometimes to people who are not chronically ill during reconditioning or athletes during very hard exercise) but if you taste blood in your mouth every time you go for a run or hop on an elliptical, that's something you should probably get checked out.
Also, asthma is a chronic illness with effects far beyond getting a little wheezy. If you've ever been treated for asthma and are not being treated for asthma now because you "grew out of" asthma attacks or they're "just seasonal" or "only when I exercise" you should know that an asthmatic person has a different inflammatory response to allergens and has immune reactions that are not the same as a non-asthmatic person, which can put you at risk for more severe or extended responses to viral or bacterial infections. If you've been treated for asthma in the past and are not being treated for it now because you don't have asthma attacks anymore, that's something that is worthwhile to check in with your doctor about to see if you should be getting some kind of ongoing treatment aside from the five year old rescue inhaler in your medicine cabinet.
An itchy stingy feeling in your lungs when you’re breathing heavily or having trouble breathing is also not something that happens to most people, that’s the inflammation from the asthma in your bronchial tubes. “I don’t have *difficulty* breathing or feel short of breath when I’m exercising or during allergy season, but I do feel like I’ve got mosquito bites down my throat that I can’t scratch that only go away when I’ve had a little time to settle.”
Cool, even if you’re not audibly wheezing or struggling to breathe that’s a symptom please go to the doctor.