Hydration status and kidney injury in the 100-mile Western States Endurance Run 🥵

Data from one of the World's toughest ultramarathons.

Hypohydration Augments the Acute Increase in Urinary Biomarkers of Kidney Injury Following the 100-mile Western States Endurance Run

Study Details

This new study examined the acute effects of the Western States Endurance Run on…

🧬 Urinary acute kidney injury (AKI) biomarkers

🩸 Kidney blood blow

…whilst assessing the influence of race pace and hydration status in 36 runners 🔍

Here is what they found ⬇️

Key Findings

🔬 Urinary AKI biomarkers (nephrin, IGFBP7, and IGFBP7•TIMP-2) increased post-race

🥵 Hydration status declined, with only 8 of 35 runners remaining euhydrated post-race

🏁 Finishing euhydrated attenuated increases in AKI biomarkers

Faster race pace correlated with increases in…

👉 urine specific gravity

👉 urinary creatinine

…but not creatinine-indexed AKI biomarkers ❌

Kidney blood velocity and conductance were unchanged ❌

Conclusion

Finishing ultramarathons in a hydrated state appears to help mitigate increases in kidney injury💧

Athletes should understand sweat rates and follow a specific drinking plan to support maintenance of hydration status ✅

Reference

https://journals.physiology.org/doi/abs/10.1152/japplphysiol.00289.2025

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