I am a 23 year old competitive gymnast and I started developing some back pain over three years ago, mainly during tumbling type stuff. About 15 months ago I was told to stop tumbling/vault...essentially stop using my legs with the purpose of calming down the back pain. Over the next few months I was put on numerous rehab plans and protocols, all of which did pretty much nothing. This past fall, almost a year ago now, I was diagnosed with a spondylolysis of the lumbar spine...basically a stress fracture in L5. This isn't uncommon for gymnasts and typically they would throw you in a brace for a few months and restrict a lot of activity. However, they didn't do that; they put me on another rehab plan and continued to restrict my lower limb activity. This past March I was also found to have a few buldging discs, L3-L5. This didn't really change things too much as my season was coming to a close in early April and these weren't bothering me too bad.
After season, I decided to head out on my own rehab plan. I figured 6 or 7 months was long enough for the spondy to heal and began using and working my legs/core a lot. I also focused on correctly my anterior pelvic tilt which was contributing to the disc problems; so I started doing lots of extension work and stretching out some tight areas. I also incorporated squats, deadlifts, and other accessory exercises, all of which I had never done before. After only 3 weeks of my rehab protocol, my legs and back felt better than they have in the past 3 years. I noticed a significant difference doing skills as well where my body felt much more controlled and together. My legs, which had basically withered away into useless extraneous masses, now have some good muscle and definition. Now I can tumble, run, and lift almost unrestricted...I am not totally confident in my back yet, but am getting there.
Anyway, yes, I believe that squats, deadlifts, and leg/back work played a large part in correcting my back problems.