Jogging induced asthma?

Question
I'm a 40 year old in middling physical condition. And, my body hates to jog.  I can't come to any other conclusion.   I've been swimming 1-1.5 km 2-3 times a week for 2 years.  No heavy breathing when I finish, heart rate below 130 after a mile in the water.  I ride 50 - 100 km a week during warm weather months, walk the course when I golf and do the Royal Marines calisthenic program a few times a week (and breath very hard during that, no question, but without asthma symptoms).  
So, yesterday, I tried to run with my 8 year old, as he's going to be doing a short   "mini-marathon" (1.5 k) for early elementary kids in June.  200 meters in, I can feel my bronchiae going into full on "crimped hose" mode, and I'm sucking wind even while falling behind my son.  We got through 800 meters, and I needed to walk off the asthma spasm.  After that, I was able to do wind sprints with him, no problem.  But, when I tried that regular old jogging pace again - bang! - everything closed up, and I was sucking wind again.
Can you tell me why I can swim, bike, sprint and do fairly challenging calisthenics without asthma, but 200 meters into a light jog, I feel like I'm breathing mustard gas?  Help!  

Answer
Sorry, I can't answer this, I'm not an expert in the asthma-like symptoms you are dealing with.  The only thing that comes to mind is the demands on the body.  In swimming, your body is buoyant enough and not really working that much against gravity, just the forces of the water.  There's also no eccentric loading on the muscles with swimming.  With biking, your body isn't going through 'pounding' actions like it does with running, so you can workout very hard on a bike and perhaps not have any breathing problems.  Running, in general, has a lot of up & down motion to it, and all that energy transfers throughout the body.  

Another thing to keep in mind is that with running, if you have never done it consistently and try to go all-out, or even what you percieve as 'easy', your body still hasn't fully adapted to the full stresses that running places upon it.  Even runners who take time off will have to gradually ease back into doing walk/run workouts for periods of time, alternating between each, such as 1 minute walk, 1 minute jog.  It would be the same for a reversal of roles: if you are a consistent runner, and try to hop on a bike, or go for a swim, your body isn't going to be directly 'in-shape' for that activity right away, and you'll be using muscles in new ways that you aren't used to.  This happened to me when I tried to do triathlons at first.  I had to gradually get used to bike riding and swimming, because those weren't my primary modes of exercise.

I hope this helps explains things more, I would suggest however talking to a doctor about exercise-induced asthma if you have a history of breathing issues.

I hope this helps you well,
Rick Karboviak