Biomarkers of organ stress and injury following the Boston Marathon.

We examined changes in blood and urine-based biomarkers of organ stress/injury and hydration before and after the 2024 Boston Marathon. Our primary aims were to compare responses between males and females, and euhydrated and hypohydrated runners. Seventy-two runners (34 males/38 females; 50 ± 11 years; finish time 3:45 ± 0:32 hrs:min) had blood and/or urine samples taken before and after the race. Average temperature on race day was 19±3 °C and relative humidity was 47±15%. Samples were assayed for markers of hydration, intestinal injury (IFABP, sCD14), skeletal muscle damage (CK), and acute kidney injury (TIMP-2, IGFBP7, NGAL, KIM-1, creatinine). Markers of hydration were elevated from pre- to post-race, but only 25-34% of runners were deemed hypohydrated post-race. All markers of organ stress/injury were increased post-race (fold change: 1.3-1455; p≤.007 for all indices), however there were no differences based on sex or hydration status (p≥.099 for all indices). Our findings show that the Boston Marathon produces a significant level of stress on the gastrointestinal and renal organ systems, and that these effects do not appear to be modulated by biological sex. In addition, our findings suggest that the substantial increases in markers of kidney and intestinal barrier injury persist even when severe hypohydration is prevented suggesting that during the marathon maintaining hydration cannot fully offset risk for organ injury. These findings should be considered when considering interventions to minimize gastrointestinal and renal related health complications associated with marathon running to promote both health and performance in recreational, but completive marathon runners.