156 Chapter 7: Training for Mobility While spinal abnormalities and age-related changes of the spine do not necessarily guarantee low back pain, they can in some cases increase the potential for low back pain. For example, heavy strength training has been shown to thicken certain portions of the lumbar vertebra (e.g., facet joints) thereby decreasing the size of the spinal canal (an opening in the lumbar vertebra that encompasses the spinal cord). These adaptations to heavy strength training are not necessarily bad, but can, when combined with other age-related disc abnormalities, increase the likelihood of the lumbar and sacral nerve roots being compressed thereby resulting in sciatica (a condition in which pain radiates down one or both legs). Figure 7.16 depicts the anatomy of a lumbar vertebra. Figure 7.16. Anatomy of a Healthy Spine (Left) and Spinal Stenosis (Right) According to Zatsiorsky & Kraemer (2006), the intervertebral discs are most susceptible to damage when leaning, bending or performing rotational movements. During these movements, the nucleus pulposus (jellylike center of the intervertebral discs) is shifted to the side opposite the lean. Depending on the load used and/or condition of the intervertebral discs, the resulting pressure can exceed the mechanical strength limit of the discs and cause the nucleus pulposus to protrude from annulus fibrous (strong outward wrapping of the discs). If this happens, the disc bulge can press against the spinal cord and cause nerve pain, numbness and/or weakness. Zatsiorsky & Kraemer (2006) provide several recommendations for protecting the lower back while strength training. Recommendations include the use of proper breathing and bracing and weight belts while lifting. The Valsalva maneuver is a particular method of breathing and bracing that increases intra-abdominal pressure (IAP) thereby providing additional support to the spine. If done properly, the Valsalva maneuver can reduce the compressive forces on the intervertebral discs by as much as 20-40%. Proper Valsalva performance can be achieved through the training and activation of the muscles comprising the abdominal wall (i.e., erector spinae, rectus abdominis, oblique muscles, intercostals and diaphragm). Zatsiorsky & Kraemer (2006) found that back pain occurs more frequently in individuals with weak or non-proportionally developed abdominal muscles. Similar to the Valsalva maneuver, the use of weight belts can also help increase IAP and decrease the relative spinal load on the intervertebral discs. Other methods that can be used to help restore the dimensions and properties of the intervertebral discs include massage,
RkJQdWJsaXNoZXIy MTM4ODY=