Huh.
This is very pertinent since I had my back go out a couple weeks ago. I'm limited to sleeping in Junior's bed now, any other sleeping surface (except maybe the family room floor) is too soft - I wake up in excruciating pain. I thought it might be the back extensions I started doing (zero lbs to max 15 lbs).
I think I'll limit my exercises to stuff that works the core as a whole, like squats and lat stuff, not target my back specifically.
My hamstrings are really tight, and lifting, even as briefly as I've done so far, really demonstrated to me just how tight they are, although it's probably also related to my back spasming.
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"...during the Lance years, being fit became the No. 1 thing. Totally the only thing. It’s a big part of what we do, but fitness is not the only thing. There’s skills, there’s tactics … there’s all kinds of stuff..." Tim Johnson