When I'm keeping track of things in a notebook, I only write on one side of the page (unless I'm in danger of running out of pages) for regular writing. I use the right hand side for my written notes, etc. On the left side, I put whatever add'l information I might have--a sketch of a new technique, map, etc. That keeps my notes pretty clear.
I have been doing this with my notes in school. I wish I had started doing it earlier. The blank side is great adding additional information. I don't do it with my gym log though. But I have started keeping track of my gym routine with my own shorthand.