One of the more concerning problems I had during my most recent 100 mile event, was blood in my urine. I had never heard of anyone experiencing this particular issue. When I saw the blood at mile 50, I knew I had to make a decision and had four options: drop out of the race, walk and drink a lot of water, continue running and risk making it worse, or take a break and see if it clears up.
I chose to walk and drink a lot of water. It did clear up and I was able to finish the race, but struggled with nausea through the rest of the race. I had hydrated well before the race and I paid special attention to hydrating during the race, since I’ve had issues with hydrating before. I concluded it was the combination of dehydration and taking Aleve, for my hamstring. After the race, I decided to do some research to determine if I needed to go to the doctor.
Blood in your urine (hematuria) is not a common issue runner’s deal with, but it does happen in some runners. The typical causes of hematuria are infection, trauma, kidney stones, cancer, blood cell disorders, medications and strenuous exercise.
Doctors don’t know exactly what happens for there to be blood in a runner’s urine. They think it could have to do with dehydration, blood cell breakdown, or bladder trauma. There is a theory that if someone voids their bladder right before a strenuous run, the walls of the bladder slap together (disturbing thought) during the run and cause traumatic blood loss.
Blood can be present in the urine if the blood vessels surrounding a specialized membrane that helps filter blood and produce urine, if they become more permeable which can be caused during exercise.
Another potential cause is related to hemoglobin, which is red. The theory here is the impact of our feet on the ground while running damages blood cells and releases the hemoglobin which then gets filtered out through the urine.
In my search of potential causes, I found that this uncommon issue is not all that uncommon among ultrarunners and is typically related to hydration problems.
So if you have blood in your urine during or after a run, hydrate and don’t freak out. If it continues for more than 24-48 hours you should go to the doctor and get checked out.