That's a good point (alophysio) ... didn't think of that.
Related to that, there has been some good recent research re. breathing patterns in relation to pain. If the patient changes their breathing pattern (i.e. change in ratio between inspiration and expiration), it has been shown to have significant effects on pain patterns and recovery from injury. May be useful to look at it in addition to everything else.

(Just want to add.....sorry, I got my miles and kilometers mixed up! I was thinking she was 21km in to a 42km marathon rather than 21miles into a 26mile marathon! I've been thinking to myself...."Holy crap! This woman is a MACHINE!!!" )