The collapsed endurance athlete ‐ time to rethink our management?

The belief that dehydration‐Induced hyperthermia explains the exercise‐associated collapse found In marathon runners and other endurance athletes is widely held; yet there is little published scientific support for this conclusion. This article reviews the evidence which shows that neither hyperthermia nor dehydration are common findings in endurance athletes regardless of whether or not they collapse. Rather, the exercise‐associated collapse conforms almost exactly to the description of a post‐exercise postural hypotension reported in unacclimatized soldiers on first exposure to exercise in Jungle heat during the Second World War. The condition resolved spontaneously with supine rest in a cold environment and was prevented by repeated exposure to exercise in the heat. One of the unfortunate consequences of this overemphasis on dehydration as the sole cause of exercise‐associated collapse has been a rising Incidence of hyponatraemia in runners and triathletes who ingest excessive volumes of fluid during ultradistance races. The injudicious use of Intravenous fluid therapy is also responsible for the latrogenic production of hyponatraemia in some collapsed athletes. If exercise‐associated collapse is Indeed due to postural hypotension, then treatment should primarily aim to reverse the conditions responsible for its development. These include elevating the legs and lowering the skin temperature to induce venoconstriction in the lower limbs. A protocol for determining the appropriate treatment for collapsed runners is proposed.