damn that's a heavy deadlift set. don't think i've ever done 5s that high up
and i also wouldn't bet my knees on loading the bar either. stumped for answers there sorry. good dynamic stretches would basically be deep-knee-bends and leg swings i think, as well as lunges.
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Je suis toujours serieux. D'autrefois, personne ne me penserait serieusement.