Acute Kidney Injury and Ultra-endurance Running

This study aims to understand how participating in the Western States Endurance Run (WSER), a 100-mile ultramarathon, affects kidney health. Long, strenuous exercise in hot conditions can temporarily strain the kidneys, especially when combined with dehydration, muscle breakdown, and the use of common pain-relief medications such as ibuprofen. Although kidney stress has been reported in endurance sports, no study has examined it directly in runners during the WSER using newer, more sensitive urine markers of kidney injury. Runners who volunteer will complete brief assessments before and after the race. These include providing a urine sample, a small finger-prick blood sample, a body-weight measurement, and answering a short questionnaire about pain-medication use. During the race, participants will wear a global positioning system (GPS) watch and heart-rate strap to monitor effort. Each assessment takes about 15 minutes, and no follow-up is required. Findings from this study will help determine how often kidney stress occurs in this event and what factors may contribute to it, ultimately supporting safer training and medical practices for ultramarathon athletes.