The Neutral Spine, posture, and strength. Those three go hand in hand. If you release the tension holding your [neutral] spine together, chances are that your form will ultimately suffer and break down and you will express weaknesses rather than strengthen them. In some cases you might even hurt yourself or walk away and straight to the chiropractor or worse.
We train the posterior chain a lot. As many of you already know, the posterior chain is composed of the muscles that work synergistic on your back side to extend your hips and upper torso and to isometrically contract to keep you upright. Translation: these muscles constantly work to oppose and counter gravity, especially under load (think: clean, dead lift, pulling, kb swinging).
Our hamstrings and glutes do much of the "work" during the movements, but what is holding the back together in neutral? Surely it would help if those muscles were well developed. Well, indeed it would. Long story short: develop your ERECTOR SPINAE! If you have more strong muscle holding your spine upright and not letting the spine flop forward, you will lift more weight. Period. You will be a better athlete. Period. You will experience less back pain and will keep your hamstrings, lower back, hips, and neck well-protected against injury and decrepitude. Period. In short, it would behoove everyone to turn what are likely flat, tight, erectors from all the sitting we do into something that would resemble the steel cables that hold bridges together. Seriously.
Take a look:
Lets look at the applied value. Who would you trust more under a heavy bar or to win at anything: someone with their vertebrae protruding through their shirt or
Pole Vaulting has to be one of the greatest sports ever and it's no wonder that pole vaulters often win the competitions where they make them compete in every other event other than their own. Best all around athletes. We see them out on the track daily and watching them is inspiring enough, let alone watching them compete. Sergey Bubka (Ukrainian pole vaulter) won athlete of the year on numerous occasions and gold medalist Yelena Isinbaeva was voted athlete of the year in 2009. FYI.
For more images of girls with extremely well-developed erector spinae who also happen to pole vault incredibly well proceed here: http://thechive.com/2010/08/16/pole-vaulting-my-new-favorite-sport-24-photos/. Note: I really did try to find pictures of guys, but all I got was beefy body builders and it's hard to drive the "athletic" point home when the rest of the muscles are over-developed as well.
Here's some things that will help put meat on your lower backs.
You can even do lots of supermans. Also stretch the low back out and work on mobility not just up and down but side-to-side and twisting.
Once the neutral spine strengthens, squat depth improves because the hamstrings don't have to stress to keep the back upright. I hope I've made the case for developing an intimidating, note-worthy back-musculature.
Hopefully this gives you some ideas of what to do this week and further on.
Have at it.