I wonder if lactic acid, cold weather, dry skin, warming-up exercises has anything to do with it. When I do low key exercise like gardening or swimming, I do not itch. Anectdotally people have advised that once the itching starts, one must just continue exercing, and it will eventually disappear.
I wonder about long term use of antihistamine if the condition is not so severe.
I have done skin tests for allargies which have come back negative.
Please feel free to engage at a higher academic level or refer further(I happen to be a specialist family physician)
You need to stop the exercise session rather than continue when urticaria occurs.The danger of a serious anaphylactic reaction occurring after continuing exercise cannot be ruled out.Dry skin and cold weather may predispose to itching.Use of leukotriene modifying drugs like Zafirlukast(Accolate) and Zileuton(Zyflo)apart from monteleukast will help prevent the urticaria.Omalizumab is a recombinant humanised monoclonal antibody against IgE/Immunoglobulin E.It acts by binding free IgE,thus reducing mast cell degradation.Successful treatment has helped in a few studies by eliminating the problem in some patients.Use of nonsedating antihistamines may help control the condition if severe.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3020292/ is a site of interest.