One of the most common areas people try to self-treat is the lower back. This is either done with something like a lacrosse ball or a two tennis balls taped together. But this can do more harm than good.
If your lower back keeps getting irritated, it's most likely a lack of stability rather than a lack of mobility. One of the most effective ways to create stability through the pillar (shoulders, hips, core) and maintain long-term movement pattern reeducation, is through this plank progression.
Check out this plank series that includes the RKC plank and side plank which increase stability through the four layers of the abs, iliopsoas, lateral hip group and quadratus lumborum. Your lower back will thank you.
Chris Shugart recently wrote an article about balance. Basically he said, "Balance good, karate good, everything good. Balance bad? Better pack up, go home."
Arnold Schwarzenegger did a lot of things wrong. He performed endless sets of leg extensions thinking that he was "cutting up" his thighs. He believed that pullovers would spread the rib cage and pull-ups would widen the shoulder girdle by spreading the scapulae.
A lot of you have been training for years, and as such have experimented with dozens of training methods. Most are probably long since forgotten, like the girl with the braces and padded bra that you dated once or twice back in high school. There wasn't any chemistry and you went your separate ways.