It's hard to tell what really happened, as he has no recollection of the time before the accident. The rescue party, alarmed by his wife, found him laying on the trail, unconscious and in severe hypothermia. The thing is, while he was running in his relatively light running clothes (the whole run was supposed to take only 40 minutes), the weather suddently turned for the worse, with temperature drop and snow fall. Hard to tell if he lost consciousness just because of the cold or if something else was also a factor.