On those occasions when I run for even just 5 minutes, it results in gross hematuria immediatly thereafter. If I just walk, there's no appearance of any blood
in my urine. At one time, I ran 25 miles a week, with no problems. However, this started approximately 7 years ago. There is absolutely no occurrence of this unless I run, but even a brief run of a half mile causes substantial blood to appear. I'm only 25, but my father developed kidney cancer.