Abstract
Objective
Ultramarathon foot races of distances greater than the traditional 26.2 mile marathon are increasing in popularity, attracting more than 70 000 annual participants worldwide. Prior studies have consistently documented renal function impairment, but only after race completion. The incidence of renal injury during these multi-day ultramarathons is currently unknown. This is the first prospective cohort study to evaluate the incidence of acute kidney injury (AKI) in runners during a multi-day ultramarathon foot race.
Methods
Demographic and biochemical data gathered via phlebotomy and analyzed by iSTAT (Abbott, NJ) were collected at the start and finish of Day 1 (25 miles), Day 3 (75 miles), and Day 5 (140 miles) during Racing The Planet's 150-mile, 7-day self-supported desert ultramarathons. Pre-established RIFLE criteria, using creatinine (Cr) and glomerular filtration rate (GFR), defined AKI as “No Injury” (Cr < 1.5 × normal, decrease of GFR < 25%), “Risk” (Cr 1.5 × normal, decrease of GFR by 25%–49%), and “Injury” (Cr 2 × normal, decrease of GFR by 50%–75%).
Results
Thirty racers, 76% male with a mean (± SD) age of 39 ±10 years, were studied during the 2008 Sahara (n=7, 23.3%), 2008 Gobi (n=10, 33%), and 2009 Namibia (n=13, 43.3%) events. The average decrease in GFR from Day 1 start to Day 1 finish was 28 ± 25 (P < .0001, 95% CI, 18.5-37.6); Day 1 start to Day 3 finish was 29.6 ± 20.1 (P < .0001, 95% CI, 18.4-40.7); and Day 1 start to Day 5 finish was 30.9 ± 17.5 (P < .0001, 95% CI, 20.8-41). Runners categorized as Risk and Injury for AKI after Stage 1 was 44.8 % and 10%; after Stage 3, 67% and 13%; and after Stage 5, 57.1% and 7.1%.
Conclusions
The majority of participants developed significant levels of renal impairment. Given the changes in renal function, potentially harmful nonsteroidal anti-inflammatory drugs should be minimized to prevent exacerbating acute kidney injury.