User blog comment:SilenceInTheLibrary/Annie's Future/@comment-4361160-20130826214228/@comment-5047068-20130913014156

Really? I thought Armin had noted in chapter 48-ish that Reiner had hardened his joints, and that was why he was going so slow even when they were trying to escape? Reiner's natural speed is agiven, i think he just wasn't expecting Eren in 44. His joints were exposed at that instance, right?