During the break in to the castle towards the end of A Princess Bride Wesley cannot walk or move other than turn his head, speak and occasionally move his fingers. However he seems to suddenly recover enough limb power to walk/crawl to Buttercup's bed. A few minutes after that he is able to stand and hold a sword. He is then apparently fine with jumping from a window and riding a horse.
Why does he go the entire break in with little recovery but as soon as the other characters leave he seems to recover fully in about 10 minutes?