Biochemistry in Endeavor Adventure Racers Study (BEARS)

Adventure sports events consist of a combination of two or more endurance disciplines, such as orienteering, running, and rock climbing, that range from a day's to a week's duration. No studies have examined acute kidney injury (AKI) in adventure sports athletes.

To describe the prevalence of AKI in participants in the Endeavor Team Challenge, a 30-hour, 40-mile adventure race.

In this prospective observational study, body weights were recorded at race registration. At the finish line, blood sample results by point-of-care testing and weights were recorded. Changes in serum creatinine (Cr) from an estimated baseline value and severity of AKI were calculated, with "risk of injury" defined as 1.5 x baseline Cr, and "injury" defined as 2 x baseline Cr. These two categories of AKI were combined to calculate the total prevalence.  Results: There were 88 enrolled study participants with complete data available on 46 (52%). The mean age of those enrolled in the study was 36.8 years (+/- 7.7), 90% were males, and body mass index (BMI) was 25.7 kg/m² (+/- 2.4). Of the competitors who completed the study, 34 (73%) had some degree of AKI, with 27 (58%) found to be at "risk" and seven (15%) with "injury". There was a significant correlation between weight loss and elevated Cr (r = -0.29, p = 0.047), with a trend towards nonsteroidal anti-inflammatory drug (NSAID) use being correlated with AKI (p = 0.058).

Acute kidney injury was observed in the majority of the Endeavor Team Challenge adventure racers, similar to what has been observed in multistage ultramarathons, and greater than after standard marathons and single-stage ultramarathons.