可能是Exercise-induced hives. 这里有篇医学文章可供参考

Exercise-induced hives 
During exercise, your body releases histamines, which can trigger an allergic response that causes rashes and hives. This reaction is similar to an allergic reaction to dust or pollen, and the rashes usually go away within 30–60 minutes after you cool down. However, some people may be sensitive to histamines and experience more prolonged or painful rashes, along with other symptoms like headaches, diarrhea, or shortness of breath. To help with exercise-induced hives, you can try taking an antihistamine like Zyrtec, Benadryl, or Allegra. Your dermatologist can also recommend other treatments.

?https://www.mayoclinicproceedings.org/article/S0025-6196%2811%2963475-7/fulltext
 

有点意思。文中建议运动前四小时不要吃东西