I am really enjoying Robert Macfarlane's 'The Old Ways: A Journey on Foot' (2012), with its evocative descriptions of walks and other journeys, as well as reflections on the act of following a path.
One thing he dwells upon is the relationship between writing and walking (and by implication running too), both of which trace lines and consist of a kind of up/down motion while moving forward:
'As the pen rises from the page between words, so the walker's feet rise and fall between paces, and as the deer continues to run as it bounds from the earth, and the dolphin continues to swim even as it leaps again and again from the sea, so writing and wayfaring are continuous activities, a running stitch, a persistence of the same seam or stream' (p.105 in the Penguin edition).
Of course he is not referring here to the kind of stitch you get in your side when running, but the running stitch in embroidery worked by the needle going in and out of the fabric just like my runner's feet going in and out of the mud in cross country this week. I am quite taken with the notion of running as a kind of landscape embroidery, stitching lines across the earth. On tarmac or track these mostly leave no trace, but in muddier conditions the running stitch is a visible line.