What does "洪荒少女" mean?

游泳运动员傅园慧 里约奥运会100m仰泳比赛结束后，她接受访问时开玩笑说“我昨天把洪荒之力用完了，今天没有力气了，可能是我手太短了吧”一举成名 （虽然最后还是获得了铜牌）

ENSwimmer Fu Yuanhui. After the 100m backstroke competition at the Rio Olympics, she jokingly said in an interview, 'I used up all my primordial power yesterday, so I have no strength today. Maybe my hands are too short.' She became famous overnight (although she still won a bronze medal in the end).