Dead, Alive, then Dead again.

In Prologe of the Wife of Bath, on page 279-280 after her fourth husband hits her because she ripped his book, she says, "And down I fell upon the floor for dead." Then after she tells him, "O have you murdered me, you robber, you" he says he shall never hit her again, and fears for her. She sits up, smacks him in the face, then lays back on the floor, and says, "Now let me die, I can't speak anymore."

If she had the engery to smack her husband on the face, she should be able to live, or at the very least speak. Why did she have such a burst of energy when she was supposed to be laying as if dead, then afterwords, couldn't speak because she is so near death?