Why did I find some blood clots when I pee 2-3 hours after I sprint run while doing treadmill. That was no blood clots if I didn't do the running.

Hematuria. Strenuous exercise can cause hematuria, or blood in the urine. While it can occur with any type of activity, runners are particularly prone to this problem. Women that exercise heavily may also note erratic menstrual patterns or unusual vaginal bleeding, virtually always in concert with some other underlying condition in which vaginal bleeding is not normally a feature.