The Thoracolumbar fascia (TLF) is an important structure for movement and stability in the human body. It intimately blends the latissimus dorsi with the gluteal complex, thus linking the arm to the leg.
In the awesome book, Fascia by Schliep, it is suggested it also has a few more roles. It is a sheath around muscles to reduce friction, facilitate blood return to the heart, provide an exoskeleton for other muscles to attach and finally, to protect blood vessels from mechanical damage.
It is finally being researched as a potential pain source for "non specific low back pain." For that to fit the bill it would need to contain enough sensory fibers. Even in 2006, this was not even thought to be looked into. Recently, experiments have been conducted on animals and the data is showing that there are indeed enough sensory fibers to convey nociception (pain.)
What I found most revealing about these experiments was that the researchers concluded that DOMS (delayed onset muscle syndrome) showed in human trials the fascia around the over exercised muscle become more sensitive then the actual muscle.
A way to train this I believe is a take away from Mike Boyle's book "Advances In Functional Training."
Force is transmitted from the ground through the leg to the hip via the biceps femoris (hamstring) and glute max. The force is then transferred across the SI Joint into the opposite latissiumus dorsi. For this reason, all rowing motions except the inverted row are performed with only one foot in contact with the ground. One foot on the ground and the load in the hand opposite that foot, the athlete must now engage the biceps femoris and glute to transfer force from the ground via the pelvic stabilizers and the hip rotators. (big thanks to Stu McMillan for sharing his notes with me) PS. make sure to check out his blog.
In doing the above mentioned, you will be strengthening the Thoracolumbar fascia.