On an unusually warm and humid day in Houston ( Jan. 30,2010) the Houston marathon was held.According to this local TV report,a female runner had an apparent seizure near the finish line.She was treated on the scene , experienced two cardiac arrests and was successfully resuscitated,intubated and transported to a hospital.Further details are not available.
One of the first things that comes to mind is exercised associated hyponatremia (EAH).
EAH has attracted much attention in recent years. Dr. Tim Noakes,from Cape Town ,South Africa, attributes the apparent increase incidence of the condition to overemphasis of encouraging runners to drink liquids past the point of reasonable and safe short term replacement needs. Subsequently more physiologically reasonable recommendations regarding drinking during longer races have been issued. The New York Marathon's fluid replacement advice was 8 ounces every 20 minutes. The International Marathon Medical Directors Association (IMMA) recommended 400-800 ml per hour. Too often in the past the advice seemed to be drink as much as possible.This advice seemingly lead to some slower runners ingesting so much liquid that they actually gained weight during the event.
Acute EAH has been associated with cerebral edema and non-cardiac pulmonary edema. With acute lowering of the serum sodium and less than instant re-equilibration of cerebral intracellular solutes, water moves into brain cells. If untreated in severe forms, cerebral herniation can occur with brainstem compression. Judicious amounts of three percent saline I.V. has become the consensus treatment.
Here is an earlier blog entry on putative mechanisms in EAH.
An elite runner collapsed and died early on in the marathon trials in New York and at least early reports indicated no specific cause was determined. Exercise associated hyponatremia was not a likely cause in this case.See here for comments regarding causes of sudden death in athletes.
Marathons in hot weather can be a disaster ( the Houston weather was merely warm and humid) which is how some reporters described the ill fated 2007 Chicago Marathon. See here.