My wife gets a rash when she exercises. I jokingly tell her that she is allergic to exercise. After about five minutes of it, even walking, she starts itching and develops fine red spots. We would appreciate any thoughts you might have as to cause and remedy. Allergy to exercise is not far-fetched.
Exercise triggers a quasi-allergic reaction in many people.
Exercise-induced urticaria is an example. Urticaria are hives. In addition to skin welts, this reaction can lead to labored breathing and a drop in blood pressure. Your wife does not have this type of exercise allergy. My bet is that she has cholinergic urticaria.