I'm not sure, what, specifically, you mean by 'lower body flexion'. But I think that the answer to your question is that my training methodology is an efficient way to reach my goals. My hamstrings, glutes, quads, hips are all strong, I like the way I look, and I'm consistently seeing improvement. And nothing hurts. I believe that squats are the absolute best overall leg builder for me, so if I have the option of doing leg curls, extensions, presses, etc, or doing more squats... I'll almost always choose to do more squats.