The lumbar spine, part of the “core”, provides mobility and stability to movements of the back, while the lumbar discs absorb shock during movement. Your low back is best protected when it remains rigid and maintains its neutral curve.
Neutral Spine, Abdominal Brace and Minimal Twisting
To protect your low back during exercise maintain a neutral spine, an abdominal brace and eliminate trunk twisting:
To find neutral spine: Arch your low back, increasing the curve (while staying upright) as much as you can (this is extension). Now, come back out of the arch until you are just comfortable and your back muscles seem slightly active.
An abdominal brace is a co-contraction of the muscles of the abdomen and back. One way to accomplish this is to tighten the muscles of your abdomen especailly below your naval. This should also activate the muscles of your back.
When you perform activities with weights or resistance there should be no twisting or forward bending of the low back. Keep your shoulders squared with your hips - turning comes from the hips and legs. This way you develop power with your hips and legs, not your back.
Disc Injury Results From Repetitive Or Sustained Flexion
The spinal disc, located between each vertebra, is injured as the result of trunk flexion. Disc injury has been shown to be related to three factors: full end-range flexion in younger spines (due to higher water content in young spines); repetitive end-range flexion loading motion in excess of 20-30,000 cycles; and, an epidemiological association between disc herniation and sedentary sitting occupations.
During forward flexion the disc is compressed and pushed backwards toward the spinal cord and can tear. This tearing occurs from the inside out and you will not feel this process until the tear reaches the outer, pain sensitive layers of the disc. At this point you may experience low back pain. With tearing of the outer layers, the disc can bulge and irritate the nerve that travels down your leg. This pain often feels like it is coming from your leg.
Most Low Back Injuries Are The Result Of Poor Motor Control
Because stability in movement comes from coordinated cocontraction of the abdominal and back muscles, when timing of muscle activation slows down you cannot always stabilize your back quickly enough. Furthermore, once pain begins, the core muscles that stabilize your low back begin to dysfunction, they fatigue easier and they activate later in the movement. If this pattern persists it becomes habitualized and is not restored to normal, even after the pain has resolved.
Because of this residual inefficient stabilization pattern from a previous pain episode or a chronic pain pattern, when you perform a movement that occurs too quickly for your back to stabilize, you reinjur it. This usually occurs with minimal tasks, like picking up a pencil, when you are relaxed, move quickly and the back muscles do not respond well enough to stabilize you during the movement.
Most low back injuries are the result of poor motor control, not excessive overload. Therefore, proper training focusing on core coordination, balance and endurance is the key to correcting these underlying dysfunctions.
Treatment for Your Low Back Should Include Both Chiropractic and Exercise
Chiropractic insures proper spinal function, which is necessary to maintain spinal stability and to establish good activation of the muscles of the back. Rehabilitation exercises should be functional in nature, that is, they should replicate how the muscles of the back and core perform during daily activities.
Exercises for the back and core should focus on endurance, not strength; they should minimize spinal loading and motion; and they should be performed with a neutral spine.
An appropriate exercise program should be paced and progressive; train correct movement patterns; adhere to good posture; and improve coordination between the back, the rest of the core and the extremities.
Explore this link for extended reading on kinesiology, assessment and exercises for the low back and core regions.