Dead lifts destroy my lower back, I feel like my problem is i straighten up my legs first then straighten my back. The problem is that if i flex my back first i have to drag the bar over my knees. Is this a form problem, or just a fact of life considering im 6'4 with nobby knees? I tried rack dead lifts today but my lower back is killing me with a shooting pain down my sciatic nerve in my right leg. Any comments/suggestions would be greatly appreciated.