Personally I think this lady apirated water into her lungs which triggered bronchospasms and or laryngospasm. Unable to transpire air she went into the typical behavior of people who can't get air when they are in the water--they will climb out of it one way or another.
IMO, it is very doubtful that any amount of prior training would have helped this woman. One of the most terrifying experiences that humans go through is the inability to "breathe". Asthmatics and those with advanced lung disesases know the feeling well and many can cope with such "attacks" by avoiding or controlling the ensuing panic. The normal healthy person just doesn't train themselves for this type of thing.