Meaning of "move out of a walk"
In George Orwell's 1984, Part 3, Chapter 4:
He attempted more elaborate exercises, and was astonished and humiliated to find what things he could not do. He could not move out of a walk, ...
The previous sentences said:
In a little while he could walk three kilometres, ...
What does move out of a walk mean? Does that mean he could not walk?
It means that his movement was limited to walking - has was unable to run, or do anything more difficult than a simple walk.
It does seem to be a strange way to say such a thing, but consider it parallel to the phrase "break into a run". Similarly structured, but with more urgent wording ("break into" rather than "move into/out of"). Although I think it is worth it to note that this structure is not used solely for running (ex: "break into song").
Update: While used, this ngram shows that it is not very common in comparison to "break into a run". (There are about 200 hits for "move out of a walk" over the past 200 years)
I'm going to fly in everyone's face here. :)
The art of prose writing does not consist merely in using stock phrases to describe new things, but in crafting new phrase and even new words, even if only to describe old things - and doing so in such a way that the meaning of the new phrase is immediately obvious.
I daresay the phrase "move out of a walk" is immediately, intuitively obvious to most native English speakers. It's actually very elegant. It is elegant and works because:
(1) It has analogs in our language that help make it intuitive, such as the aforementioned break into a run.
(2) Using a word like move, which is a fairly generic word, rather than break, which is somewhat more dynamic, helps to give a sense of lethargy. Even the word move is more given to being drawn out because all three of its phonemes m, oo, and v can be drawn out, whereas break sounds more decisive, more "snap" if you will, being bookended by b and k, which cannot be elongated but are very definitive, punctilious sounds.
(3) Being unable to "move out of" also gives a sense of being trapped, as the character no doubt felt.
I think the phrase a perfect turn of the English language, and fairly creative if the ngram is any indicator.
That all said, I can see how it might give a non-native speaker a hard time. It is unusual.