Seeing blood in your urine – medically referred to as hematuria – after an exercise session can be frightening, but it is not always a cause for concern, according to Capital Nephrology Medical Group. The cause of exercise-induced hematuria is unclear, but it is not uncommon and does not usually last longer than a few days. If you have blood in your urine for longer than two days, or you experience it consistently after exercise, consult your physician.
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Hematuria occurs because parts of your urinary tract or your kidneys have let blood cells leak into your urine. Microscopic hematuria is not visible to the naked eye and can only be seen under a microscope. Gross hematuria is blood that you can see with the naked eye. In gross hematuria, your urine will be pink, red or the color of cola. Hematuria isn't typically painful, but can be if the blood is clotted. Most of the time, you won't have other symptoms along with the hematuria.
Experiencing bloody urine after exercising is referred to as exercise-related hematuria. Its exact causes are unclear, but possibilities include lack of sufficient fluids, trauma to the bladder, or the breakdown of red blood cells that happens if you participate in sustained aerobic exercise. Runners are most often affected, but anyone who participates in intense exercise can experience it, according to Capital Nephrology Medical Group. Blood in the urine solely as the result of exercising should disappear within 48 to 72 hours.
A study published in the April 1998 issue of the "European Journal of Applied Physiology and Occupational Physiology" compared the incidence of hematuria in otherwise healthy individuals who had either run on a treadmill for 60 minutes, biked for 60 minutes or sprinted for 400 meters three times. The group that sprinted reported the highest incidence of hematuria, leading the researchers to conclude that weight-bearing intensity during exercise was more of an influence than the duration of non-weight-bearing exercise.
Consuming certain foods, such as beets, berries and rhubarb, or taking medications such as aspirin or prescription blood thinners, can cause urine to turn red. Other causes can include kidney or bladder infection. While most cases of hematuria are benign, it can be the sign of a potentially serious underlying problem, such as kidney disease or cancer. The University of Maryland Medical Center recommends consulting your physician whenever you experience blood in your urine.