Posted last year by Kelly Starrett, solid info that never gets old
From Mobilitywod:
Test: How does your back feel after a heavy extension biased work out (like heavy snatches) or Michael.
Mwod: Accumulate 10 minutes in an “ass to grass” squat. Let your back relax.
Retest: How’s the bottom of your active squat? Do your heel cords feel better? How about your back?