Back pain

[beige_alert]

Joyce and I went shopping at REI on Sunday, since I needed a few things.  I also found a few things I didn't know I needed, as usual.  As is also commonly the case, an hour or so of standing around an slowly walking around the store in the usual way left me with lower back pain.  It's quite uncomfortable but by no means debilitating pain, and after levering myself into the car and sitting down for five or ten minutes I'm fine again.  It's weird though, to compare the sort of thing that causes me low back pain, which is walking around slowly at a shopping mall or in a trade/product show (or, less commercially, a museum), with this partial list of things that do not cause me back pain:

• Running a half marathon


• Cycling 120km


• Three hours of kayaking


• Two hours of cross country skiing


• Speed skating


• Weightlifting


• Snowshoeing


• Walking 5+km outdoors at a good pace

On the one hand, this is great.  Should I waste a day at a shopping center looking at stuff I don't need and probably buying something I don't need?  No, that causes physical pain, better to do something comfortable like run 10km or do some speed skating practice.  On the other hand, WTF!?  I mean, really, WTF?!  How is it that slow walking is painful but actual athletic activity (well, slow athletic activity, but, still) isn't?