I'm not sure if I'm alone in this, so thought I'd ask...
I've just read over Waterbury's 'Iron Core' article, which states that "The ability to maintain lumbar lordosis (an inward curvature of the low back) while lifting and moving reigns king. When your trainer tells you to keep an arch in your low back while pulling a deadlift, he's telling you to maintain lordosis." Now, that's my problem.
It's taken me a good while to feel that I've properly gotten my glutes to fire during deadlifts (and squats, for that matter.) I'd always tried focusing on arching my back, but it never led me to finishing the movement with my glutes; a short while ago, I started pulling deads with my back in a slight flexion, and bingo, straight off my glutes were firing no problem and I was pulling more weight than I ever have before.
So now, I don't know what to be doing; based on Waterbury's article and the fact that I've read about dangers involved with lifting in spinal flexion, it seems like I should be avoiding it. Conversely, however, it's the only way I feel I can get my glutes properly firing- perhaps one of the most crucial aspects of squats and deads.