I just was walking and reading on my phone and found that with jostling it was easy to lose track of where I was. Could you create a stationary horizontal line on the screen that represents where your eyes are reading, and then as the user scrolls the text moves (as normal) from below the line to above? This way the eye always comes back to the line and knows where to read from. Alternatively, the line could move and the page could be stationary, but that would require a reset as you changed pages or scrolled down within the document.
Taylor Martin