I knew this topic would be in here somewhere. 
I wonder @downhiller did you get to the bottom of your issue?
I’ve just swallowed, spat, coughed and spluttered my way through a set of threshold intervals and thought “enough of this!” I wonder if there’s anything I can do. I’ve previously (2014) been tested for asthma and was at 70% capacity for my age or whatever. At the time I was given a prescription for salbutamol and some brown ‘preventer’ inhaler after an incident during a cold race, but I only carried the blue puffers during events and never really seemed to need them again (I have some still in boxes from 2016 - do they get better with age? :))
I guess the obvious answer is “go see your GP” which I’ll do but I also like to get some anecdotes and/or discussion going so I at least know something about what I’m asking.
For me, it seems my legs aren’t struggling, my HR is up but not crazy high and drops pretty well during the rest intervals but during the work blocks I’m constantly having to ‘swallow away’ gunk and/or clear my throat like some kind of smoker (I’m not a smoker). It’s not a digestive thing so far as I can tell - I can pretty much eat/drink anything and work pretty hard. My nose isn’t running. I don’t have a cold. I’ve never been an “asthmatic” save for that very cold race where I had some kind of breathing episode which prompted me to get tested.
Writing this it seems the next step is to go see GP again and see what they say but is there something I should be asking about? Like, what’s the difference between exercise-induced bronchoconstriction, or exercise-induced asthma and could I have either?
My Throat Tightens & Closes During Exercises | livestrong suggests it could simply be a lack of fitness, which I can live with but it seems at odds with the numbers I’m seeing.
I’m in London, riding inside with the window open and a fan running. Not generally that bad with hayfever although some years I’ve taken hayfever meds because it’s been bad. Pretty hit and miss though.