So this is very interesting to me as a swimmer. I find that at the peak of my curve (where I train harder for the regional meet) I often get sick more often, and for far longer. In swimming, this is catastrophic to your performance for the meet, so we try at all costs to prevent illness, but it always happens to one or two of us. The question I pose, does this just apply to shot term exercise, or does intense training (5 hrs a day) for about a month have the same effect.