Etude Des Troubles métaboliques Induits Par Une Course à Pied très Longue Distance, " La Diagonale Des Fous " de La Réunion / Metabolic Disorders in Ultramarathon Runners of the Madmen's Diagonal Race on Reunion Island

Ultramarathons are races involving walking or running longer than the traditional marathon length of 42km and frequently take longer than 12 hours to complete. These races are increasingly frequent and racers attempt to push back the limits of what their body can accomplish. However, these races are not without certain risks.

The Reunion Island Grand Raid (or Madmen's Diagonal) is one such race, crossing the island over 163 km (101 mi) with an altitude gain of 9,643 meters (31,637 ft). Temperatures vary from 0 et 30 degrees Celsius (32-86°F) and the race can take 27 to 67 hours to complete. About 40% of the racers do not cross the finish line. Each year, two or three racers are hospitalized each year in the intensive care unit (ICU) for tubular necrosis and treated with dialysis. Scientific literature shows that racers can present acute rhabdomyolysis, with elevated levels of CPK-MB. Nevertheless, there have been very few studies on the impact of these ultramarathon racers on other biological parameters. As the racers compete and lose about a liter of sweat every hour, they also lose ions and trace metals such as zinc, copper, iron, magnesium, which can have major repercussions during and after the race. These losses are akin to those observed in severe burn victims. In these patients, it has been shown that supplementation in trace elements can decrease mortality and hospitalization time.

Moreover, a major inflammatory response has been observed in racers who compete in ultramarathons. This inflammatory response is similar to that of the systemic inflammatory response syndrome (SIRS). Patients in the ICU who are septic or who present a SIRS also have metabolic diseases, and it has been shown that selenium levels are a prognostic factor of SIRS and supplementation can increase survival rates.

Investigators present the hypothesis that ultramarathon racers can have decreased levels of selenium and other ions and trace metals and that specific supplementation can limit risks and improve recovery. More specifically, investigators suggest that selenium levels will decrease by 25% after the race and remain so at least a week.