Following up on Part 1 (Here's a link to it), deadlifting is the best thing for back pain when implemented correctly.
Reasons #1,2,3 were on part 1. Here are #4,5.
Learning how to control the spine (trunk stabilization, core stability... whatever your desired term), like any other task, is best done durign functional, real life movements. So that means that sit-ups, lying on the floor, twisting are great for accessory work, but do not provide real life stimuli. These muscles are meant to stabilize over long period and through full movements - not turn on and off quickly and repetitively like in sit-ups and not over long periods of time like in a plank. Again, great exercises, but not the most functional.
Guess what I'm trying to say... Yup, gotta do deadlifts to train the trunk muscles. With deadlifts, we are going through a large range of motion through a functional movement (more on that later). The spine stabilization muscles need to react differently throughout the deadlift range of motion and will be trained differently than a static hold or repetitive crunch.
To make it even better, deadlifting helps activate the Latissimus Dorsi muscle. Wait, isn't that a shoulder muscle? You'd be correct if you were thinking that. The cool thing about the Lat is that it connects from the shoulder and scapula all the way to the Sacrum through the Lumbosacral Fascia. Because of this, it actually can function as a trunk stabilization muscle!
So, functional strengthening, strengthening through different positions, and implementing secondary mscules are all possible with deadlifts.
Deadlifting- whether you realize it or not, you do it every day. Any time you lift your children (infant car seats anyone??) or pick something up from the floor, you're doing that movement.
Although we do it all the time, this motion is a common cause of pain and injury. How often do you hear about back pain being caused by lifting a piece of paper or something else as trivial.
It is a common movement, so practice it! Add weight to it! Make sure that such a simple movement doesn't give you pain.
Varying the type of deadlift you are doing can help reinforce correct movement patterns and make you resilient to everyday movements. Belted, banded, sumo, high pulls... experiment with variations and make them as life-like as possible.
After integrating deadlifts into your workouts consistently, you'll be shocked how different typical life movements feel. As a parent, you'll pick up your children easier. the nurse will be able to position his patients better. The construction worker will not be so scared of an injured back while lifting. the elementary teacher can get down to the student's eye level without fearing back pain.
To reiterate, deadlifting is great for back pain rehab and back pain prevention. It should not be reserved for competitive lifters. Nearly everyone should be doing deadlifts or modifications of deadlifts.
BUT, don't deadlift through pain! Alleviate the pain first, then add deadlifts to fix the underlying cause, build strength, and make those improvements stick for good by building resilience.