Lecture III Muscle Imbalances


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Spinal Stability and the Msucles of the trunk and pelvis

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Lecture III Muscle Imbalances

  1. 1.  Traditional anatomy descriptions of the spinal muscles have only taken a look at the posterior view or from the back.  Muscles are typically studied or viewed as straight line cables.
  2. 2. A more current understanding of muscle anatomy involves how movement is created and joints are stabilized.
  3. 3.  Many anatomy books describe the function of the rotatores as small rotator muscles of the spine. The intertransversarii as lateral flexors of the spine.  According to McGill (2002), these muscles are very tiny and do not create movement. • However, they may function as vertebral position sensors at every thoracic and lumbar joint.
  4. 4.  Extensors of the Vertebral Column Multifidi Semispinalis Longissimus Iliocostalis Spinalis  Quadratus Lumborum
  5. 5.  The major extensors of the thoracic and lumbar spine.  The role of these muscles is different in the two areas of the spine. • Thoracic:  These muscles attach to the ribs and the thoracic vertebrae with long tendons that run parallel to the spine and attach at the sacrum and iliac crests.  The thoracic extensors run just under the fascia over the lumbar spine.  These extensors have the greatest moment or torque.
  6. 6.  According to a study from the American Journal of Neuroradiology 2005, the development of extreme thoracic kyphosis might contribute to excess biomechanical stress in the spine and may identify a population at risk for future vertebral compression fracture at the thoracolumbar junction.
  7. 7.  These muscles originate over the posterior sacrum and go at an angle and deeply attach to the lumbar vertebrae.  Injury or load to the lumbar spine increase when there is flexion of the spine. These muscles lose their angled attachment with spinal flexion increasing the load or force to the spine.  The extensors of the lumbar spine create a shearing force in flexion.  This is, unfortunately, the way most people bend over to pick something up. Therefore, increasing risk of injury to the spine and muscle tissue.
  8. 8. During lifting, muscles and ligaments significantly increase loads to the spine. In weak spines, a spinal load of 7,000N or 1,560lbs begin to damage the spine. Think of how many times you bend over during the day to pick something up! In young healthy spines, 12-15n or approximately 2,600-3,360 lbs begin to load the spine. In weight lifters with ideal mechanics, the load can increase to 4,480lbs.
  9. 9.  One avoids injury to the back when you flex at the hips, therefore reducing or minimizing tissue tension.  If you are flexed at the hips and not the spine, there is a increase in thoracic extensors and the lumbar extensors do not increase the load to the spine.  The abdominal muscles are activated by creating a “corseting” effect stabilizing the spine through abdominal bracing.
  10. 10.  According to Callaghan, Gunning and McGill (1998), to have safe therapeutic muscle activation for the lumbar extensors, one must activate one side of the spine at a time.  As discussed previously, there are four sections of the extensors. Right and left thoracic and right and left lumbar.
  11. 11.  Increases the load to the spine to 6,000N or over 1,300 lbs.  It certainly does activate all 4 sections but with injury to the spine.
  12. 12.  These muscles only span a few joints or vertebrae and the force they apply is very localized.  The multifidus does play a role in stabilizing but cannot be isolated.
  13. 13.  The “lats” are involved in lumbar extension and spinal stabilization.  The latissimus is active during pulling and lifting.  Activated in Bird Dog with arm and opposite leg activated, rows and pull downs.
  14. 14.  Trunk flexor.  Why is it segmented instead of one long muscle? • Possibly to facilitate flexion/extension of the torso and to assist with abdominal distension or contraction as volume changes ( M. Belanger, 1996).
  15. 15.  Functional point of view • Work together and independently. • The oblique's create a twisting and lateral bend and enhance flexion. • Rectus primarily creates flexion.  Upper and lower Abdominal Wall • According to Leman and McGill, 2001, there is no separation of upper and lower ab wall.
  16. 16.  The oblique's and the transverse abdominus form a hoop around the entire torso creating stability or stiffness for improved spinal stability.
  17. 17.  Attaches to T12 and to all the lumbar vertebrae and to the femur.  The psoas is a hip flexor and not a spine stabilizer Juker, McGill and Kopf, (1998). This is because it attaches to the lumbar vertebrae, creating a stiffening of the spine only when the hip is flexed (McGill 2005).
  18. 18.  Attaches to each of the lumbar vertebrae, pelvis and rib cage.
  19. 19.  The quadratus lumborum, or QL, is a common source of lower back pain.  The QL is capable of extending the lower back when contracting bilaterally, the two QLs of the low back pick up the slack, as it were, when the lower fibers of the erector spinae are weak or inhibited (as they often are in the case of habitual seated computer use and/or the use of a lower back support in a chair).  There is a mechanical disadvantage created by constant contraction while seated which can overuse the QLs, resulting in muscle fatigue.  A constantly contracted QL, like any other muscle will experience decreased blood flow, and will create muscle spasms over time.
  20. 20.  True spine stability is accomplished by a balanced “stiffening” from the entire musculature of the torso.  This includes the abdominal wall, quadratus lumborum, latissimus dorsi and the back extensors of longissimus, iliocostalis and the multifidus.  There is not a single muscle that is responsible for spinal stability like the transversus or multifidus. Very few individuals can singularly activate these muscles. By attempting to recruit these muscles by drawing in ones ab wall, one creates instability when they are attempting to increase spinal stability by “hollowing” (McGill 2009).
  21. 21.  The core muscles differ from the arm and leg muscles in that the muscles co-contract stiffening or corseting the trunk so that all the muscles work together synergistically. Therefore, training the muscles of the core is different than training the muscles of the limbs.  The core generally functions to prevent motion rather than initiate it. Activities of daily living need power to come from the hips and transmit to a stable torso. Pushing, pulling, lifting, carrying and efforts of the torso are compromised by the spine bending or what are called “energy leaks”. These energy leaks over time can accumulate and create an injury to the spine.
  22. 22.  What are Energy Leaks?  Energy leaks are caused when weaker joints are forced into eccentric contraction by stronger joints.  Energy leaks are points at which energy is lost during the transfer of force from the ground. Energy leaks are a result of the inability of the body to stabilize a particular joint.
  23. 23.  Sitting with a rounded back.  Squats with rounded back or knees that cave in.  Lifting a child, lifting groceries with a rounded back poor posture.  Walking or running with with hips that have a great deal of movement.  Energy Leaks create injury.
  24. 24.  Standing on an unstable surface.  Sit ups.  Stretches that emphasize knee to chest or toe touches.  Using a physioball does not create spinal stability. To use seated with rounded posture is a significant “energy leak”.
  25. 25. The “Bug”
  26. 26. Basic Quadruped
  27. 27. Bird Dog : Do not add leg extension and arms until basic Quadruped is mastered
  28. 28. Bird Dog with Sweep
  29. 29. Off set load with hand to the side
  30. 30. Basic Side Bridge
  31. 31. Feet can be either stacked or in front for different muscle recruitment
  32. 32. Stir the Ball
  33. 33.  Examples of what can lead to an injury further up or down the kinetic link. Old Shoes Over Pronation, Under Pronation, High Arches Back Pain Gluteal amnesia Shortened hamstrings Shortened hip flexors Psoas Quadriceps: Rectus Femoris
  34. 34.  Lateral hip pain, knee and foot injuries Gluteus medius Trochanteric bursitis IT Band Syndrome Meniscal Injuries ACL injuries Plantar fasciitis
  35. 35. Bartynski, W.S, Heller,M.T., Grahovac,S.Z., Rothus, W.E., and Kurs-Lasky, M. (2005) Severe Thoracic Kyphosis in the Older Patient in the absence of Vertebral Fracture : Association of Extreme Curve with Age. American Journal of Neuroradiology, 26:2007-2085. Nitz, A.J., and Peck, D. (1986) Comparison of muscle spindle concentrations in large and small human epaxial muscles acting in parallel combinations. American Surgeon, 52:273-277. Bogduk, N (1983) The innervation of the lumbar spine. Spine, 8:286. McGill, S.M., and Norman, R.W. (1987) Effects of an anatomically detailed erector spinae model on L4/L5 disc compression shear. Journal of Biomechanics, 20 (6):591. McGill, S.M., Hughson, R.I., and Parks, K. (2000) Changes in lumbar lordosis modify the role of the extensor muscles. Clinical Biomechanics, 15 (1):777-780.
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