yes some women do experience spotting with heavy exercise. this can represent either a less stable lining of the uterus or polyps/fibroids. let's look at both possibilities. an unstable lining of the uterus can arise from hormonal forms of birth control (e. g. pills/patch/ring/shot). it can also happen if the woman has an overly thickened uterine lining. a too-thick lining can develop if the woman is missing ovulations is perimenopausal and/or is very heavy set. classically a too thick lining will also suggest itself if there are erratic or very heavy menstrual periods. the presence of uterine fibroids or polyps of the uterine lining can also make a normal sized lining be easier to have spotting. classically there may be spotting between periods or after intercourse. bottom line if the spotting persists or increases you should see your gyn or local family planning clinic for follow up. there is no overt reason for you to stop your planned running--unless it prompts increased bleeding.
i have always had regular periods. for the past two weeks i have been spotting when i run every day. is this normal?