Not many people realize that running actually involves all of your organs, not just your muscles!
For one organ to function correctly, it needs the other organs to work correctly. Kidneys are responsible for filtering waste out of your blood. When running, blood flow to the muscles and skin is significantly higher which may decrease the blood flow to the renal system. Increased core body temperature increases the stress to the tubular system of the kidneys which can cause damage. Most people would think the increase in creatine kinase (muscle waste) is the reason for kidney damage, but this is the least common cause.
The American Journal of Kidney Disease recently published an article about the prevalence of acute kidney injury in runners after running a marathon. Urine samples of 22 marathon runners were taken 1 day prior to a race, 24 hours post marathon and 48 hours post marathon. 82% of the runners had results that were signifiant for a kidney injury. Creatine kinase levels increased significantly from day 0 to day 2.
Most people know hydration is important in the time leading up to a race, during and immediately after a race, but this research may indicate that continuing to focus on hydration is important as much 48-72 hours after a marathon. The study also found an increase in inflammatory biomarkers which may be significant of the damage repair that is happening to the kidneys. So as you’re training, be mindful of your hydration and don’t forget about maintaining your organ health!
Mansour, S. et. al. Kidney Injury and Repair Biomarkers in Marathon Runners. American Journal of Kidney Disease. 2017. 1-10.
Kathleen Leninger, PT, DPT