Adult women experience some amount of vaginal bleeding as part of the menstrual cycle, which lasts approximately 28 days. However, bleeding between menstrual periods is common, and occurs for a variety of reasons, among them trauma, infection, medications and systemic diseases involving the liver, kidneys or other organs. Women that exercise heavily may also note erratic menstrual patterns or unusual vaginal bleeding, which is virtually always found in concert with some other underlying condition in which vaginal bleeding is not normally a feature.
A cervical polyp is a growth, usually benign, on the cervix, the site at which the uterus meets the vagina. They are common, especially in women that have given birth to multiple children, and by themselves rarely cause any symptoms. Despite their ubiquity, what causes cervical polyps to form remains unknown, although the hormone estrogen is a likely culprit. Occasionally, women with cervical polyps that they are as yet unaware of experience vaginal bleeding. Physical examination then reveals the polyps, which a physical removes and biopsies to rule out the possibility of a malignancy.
Uterine fibroids are benign growths within the uterus that appear in up to 75 percent of women at some point in their lives. Because they rarely cause symptoms, most women with fibroids are unaware that they have them unless they are discovered incidentally during a procedure such as an ultrasound being given for some other reason. Fibroids most often cause problems when they outgrow their blood supply. In these cases, they can cause acute pain and abnormal vaginal bleeding, including heavy menstrual periods and bleeding during or after exercise.
Pelvic Inflammatory Disease
Pelvic inflammatory disease, or PID, affects approximately 1 million American women each year. The cause is bacteria migrating from the vagina through the cervix and into the uterus, where they may then spread to other structures, such as the fallopian tubes and ovaries. PID is usually, but not always, transmitted through sexual activities. PID should be suspected when vaginal bleeding during or after exercise is associated with malodorous vaginal discharge, fever or pain or tenderness in the lower abdomen or pelvis.
Various Systemic Conditions
According to Dr. Cathy Fieseler, exercise such as running should not in itself cause vaginal bleeding. However, a number of intrapelvic and extrapelvic diseases and conditions can result in exercise-driven vaginal bleeding, among them blood-clotting problems such as hemophilia, thyroid disorders, and liver disorders. Fieseler notes that the presence of abnormal uterine tissue can lead to vaginal bleeding during or after running. She states that some exercise-related vaginal bleeding is attributable to anovulatory bleeding, in which the ovulation that normally happens with each menstrual cycle does not occur.