I have the same experience. After a few seasons of hacking I woke to the realization i have Exercise Induced Asthma. When planning a heavy breathing interval, hillclimb or sprint effort I take a few hits of inhaler prior to riding. My wife has asthma and offers her albuterol inhaler but learned I am allergic to it. I use another kind that is prescription only, this I obtained after learning the hard way. See a doctor Team Sky said 1/3 of their riders have EIA.