For extra strength and conditioning , I'm coming back from l5s1 herniation and won't be lifting heavy for a while but I want to get strong and healthy for the mats again (been 12 months rest and core work) . What are your thoughts? 
Just work on slow, controlled exercise. The tool is not important if you are using safe methods of execution. If you prefer bodyweight exercise than just stick with the basics (push-ups, pull-ups, inverted rows, etc).
I would not recommend Gymnastics or acrobatics per-se, unless you mean stuff as I mentioned above. Coming off an injury, I would not want to start trying to flip, twist, spin, etc...just slow, smooth, strength. If you wanted to use Rings, or TRX etc, that would be fine.
Your "Mantra" should be: Movement you can control, in ROM that is pain free. A SMITH machine can be a good tool for those working on bodyweight exercises and wanting to progress back down to the floor (for push-ups) or back up to full ROM (for pull-ups).
TAKU
I have a "change" between l5s1 myself, and I've managed it for over a decade. The things that work for me:
* Range of motion, range of motion, range of motion: Make absolutely certain that you can complete the ROM required for anything that will strain your lower back and then slowly work up to using weight. For instance, I'd make sure I could do a full facing-the-wall squat before squatting more than a barbell.
* Bands - After doing nothing to it for so long, my lower back was weak. I'd do 100 band good mornings every day during the week and progress up in band strength when 100 consecutive reps was easy.
* Active Release Technique - Find a provider at www.activerelease.com / usually covered by insurance. This will help release any adhesions in the muscle and connective tissue of your back. This was a game changer for my back problem.
* Gymnastics Strength Training - Gymnastics forms the core of my routine, but you need to start gradually. Things like the plank, reverse plank, and gymnastics bridge can be great for your back and core, but you can't jump into it too quick. Always be mindful of how you feel, so you don't push too far.
I'd stay away from acrobatics until you've built yourself back up. Yoga I've found to be hit and miss. Sometimes it can aggravate my injury. Other times it feels amazing.
As a recommendation convict conditioning starts off with very basic and gentle movements and has clearly laid out progressions to harder BW strength moves.
Amazing answers guys. I'm going to start the good mornings tomorow makes sense it's terribly weak.
I should have pointed out I meant the static holds. I feel like tight calves and hammy are contributing to it. Any idea how to mobilize/stretch without aggrevating?
Truly irritating injury!
Taku your HIIT protocol is still the best!
Thanks LEMon.
Always happy to help in any way I can.
TAKU
I love yoga <3