The inquest into the death of Corporal James Dunsby heard that he suffered multiple organ failure after collapsing during a training exercise on one of the hottest days of the year.
Cpl Dunsby was one of six soldiers who collapsed during the exercise, on July 13, the court heard.
It is thought that the reservists were taking part in an exercise known as the "Fan Dance" which involves marching up South Wales's highest mountain, Pen Y Fan, and down the other side carrying a weighted pack and rifle, then doing the same route in reverse, in a set time.
More top news
The Queen says she is "deeply touched" by the "selflessness" of medical staff fighting the Ebola outbreak in her annual Christmas speech.
Video of Norman the dog's Scrooge-like disdain of Christmas is becoming a festive hit online as he moans about his owners' singing.
Pope Francis has used his Christmas sermon to condemn the "brutal persecution" of minorities by Islamic State.