There is no way of knowing whether cramping and spotting is a concern when triggered by exercise, such a situp. The best course is to assume it's a problem and see your doctor. Abdominal pain can be attributed to normal muscle soreness, but the spotting indicates this is not regular exercise cramping. Your age and general health will be a factor, as well as how often you exercise. Your doctor will help you discover what may be causing the pain and bleeding, but there are a few things you should consider.
Pregnancy
The most obvious answer is you may be pregnant. There are benefits to exercise during pregnancy, and for many women, it is safe to work out. Some women do experience cramping and spotting during pregnancy, but situps may be too much stress on the uterus. Spotting and pain early can also be a symptom of miscarriage. Make notes for your doctor. Write down when your last period ended, how frequently the pain and spotting occurs and whether it happens even if you don't do situps.
Menstruation
You may be getting your period. If you are near the start, you may trigger some cramping and spotting with situps. Excessive exercise can also change your menstrual cycle and trigger a condition known as athletic amenorrhea, which can occur for those who exercise several hours a day; the periods stop completely at some point, but minor spotting may be a symptom. Cramping may be normal menstrual cramps, and the situps just a coincidence. Stop doing situps for at least a week. If your period begins, hold off doing situps until the cycle completes. If pain continues or is strong, see your doctor.
Illness
Cervical cancer, polycystic ovary syndrome, uterine fibroid or any reproductive system disorder may be the culprit. Exercise may be irritating a preexisting condition. If it has been awhile since your last visit to the gynecologist, now would be the time. Stop doing situps until after you see the doctor.
Recommendations
Listen to your body. Severe pain is a sign something may not be right. When you add vaginal spotting to that equation, your body is turning up the volume. The spotting and pain may mean nothing, but don't take a chance. The list of possible causes is quite extensive and only your doctor will be able to tell you why you are cramping. Stop doing situps for now. If the pain is sharp or unbearable, go to the emergency room for immediate attention. If the pain is dull and uncomfortable, try a heating pad over your lower abdomen. Lie down and rest for a while. If possible, stay off your feet for a few days or until you can see the doctor.
