Body Posture & Muscles Functions: (Part 5)

For some of you personal trainers and coaches out there, you may heard of anterior and posterior pelvic tilt during your fitness or CPT courses. And for some of you people, you may be aware of 'donald duck and pink panther syndrome'. What does these terms have in common? Well, if you notice people especially women with lower back arch, we call that posture 'Donald Duck' or also known as anterior pelvic tilt. As for people with 'pink panther syndrome' or 'butt dissapearing syndrome', it is also known as posterior pelvic tilt. 

Now, let's talk about the pelvic. An area which not many people show great interest, it plays an important role in biomechanics and postural alignment. The neutral position of the pelvis is one in which the anterosuperior-iliac spines are in the same transverse plane, and in which the spines and the symphysis pubis are in the same vertical plane. An anterior pelvic tilt is a position of the pelvis in which the vertical plane through the antero-superior-iliac spines is anterior to a vertical plane through the symphysis pubis. A posterior pelvic tilt is a position of the pelvis in which the vertical plane through the antero-superior iliac spines is posterior to a vertical plane through the symphysis pubis. In a standing position, an anterior pelvic tilt is associated with hyperextension of the lumbar spine and flexion of the hip joints, whereas a posterior pelvic tilt is associated with flexion of the lumbar spine and extension of the hip joints.

Now, let's take a look at the illustration below. 

In lateral pelvic tilt, the pelvis is not level from side to side, rather, one anterosuperior spine is higher than the other. In standing postition, a lateral tilt is associated with lateral flexion of the lumbar spine and with adduction and abduction of the hip joints. For example, in a lateral tilt of the pelvis in which the right side is higher than the left, the lumbar spine is laterally flexed resulting in a curve that is convex toward the left. The right hip joint is in adduction and the left in abduction. Please see illustration below.

I will show you a measurement test which requires minimal tool (only a ruler) to determine the length of the posterior muscles. Below are details of the measurement test and illustration of different common postural status.

Equipment: Same as for hamstring length test, plus a ruler. The ruler is used to measure the distance of the fingertips either from or beyond the base of the big toe. This measurement is used only as a record to show the overall forward bending; it in no way indicates where limitation or excessive motion has taken place.

Starting Position: Sitting with legs extended (long-sitting) and feet at, or slightly below, right angles.

Reason: To standardize the position of the feet and knees.

Test Movement: Reach forward, with knees straight, and try to touch the fingertips to the base of the big toe or beyond, reaching as far as the range of muscle length permits.

Reason: Both the back and hamstrings will elongate to their maximum.

Normal length of back, hamstring, and gastroc-soleus muscles

Excessive length of back muscles, short hamstrings and 

normal length of the gastroc-soleus.

Excessive length of the upper back muscles, slight shortness of the muscles in the mid back and in gastrocsoleus. Hamstrings and low back are normal in length

Normal length of the upper back muscles and short lower

back, hamstring and gastroc-soleus muscles.

Bear in mind, trunk muscles consist of back extensors that bend the trunk backward, lateral flexors that bend it sideways, anterior abdominals that bend it forward or tilt posteriorly, and combinations of these muscles that rotate the trunk in a clockwise or a counter-clockwise manner. All these muscles play a role in stabilizing the trunk, but the back extensors are the most important in this regard. The loss of stability that accompanies paralysis or marked weakness of the back muscles offers dramatic evidence of their importance. Fortunately, marked weakness of these muscles seldom occurs.

The term weak back, as frequently used in connection with low back pain, mistakenly suggests a weakness

of the low back muscles. The feeling of weakness that occurs with a painful back is associated with the faulty alignment the body assumes, and it is often caused by weakness of the abdominal muscles. Persons who have faulty posture with roundness of the upper back may exhibit weakness in the upper back extensors but have normal strength in those of the low back.

Despite the fact that the low back muscles are the most important trunk stabilizers, relatively little space will be devoted to them in this chapter compared to the detailed discussion of the abdominal muscles. Testing back muscles is less complicated than testing abdominal muscles, and in the field of exercise, few errors occur regarding back exercises. Many misconceptions and errors, however, occur regarding proper abdominal exercises. Furthermore, in contrast to the back muscles, weakness of the abdominal muscles is more prevalent. It is important to know how to test for strength and how to prescribe proper exercises for the abdominal muscles because of the effect that weakness of these muscles has on overall posture and the relationship of such weakness to painful postural problems.

Illustrations, definitions, and descriptions of basic concepts are used to help achieve this purpose. Both the illustrations of the trunk muscles that follow and the accompanying text provide information in detail about the origins, insertions and actions of these muscles. This information is essential to understanding the functions of these important trunk muscles.

Now, let's discuss about back extensors and neck. For back extensors, to raise the trunk from a prone position, the hip extensors must fix the pelvis in extension on the thigh. Normally, extension of the hip joints and extension of the lumbar spine are initiated simultaneously, not as two separate movements. If slight tightness exists in the hip flexors, there is no range of extension in the hip joint, and all the movement in the direction of raising the leg backward is accomplished by lumbar spine hyperextension and pelvic tilt. Please see illustrations below.

For hip extensors to raise the extremity backward

from a prone position through the few degrees of true

hip joint extension, the back extensors must stabilize

the pelvis to the trunk.

A subject with strong back extensor muscles and strong

hip extensor muscles can raise the trunk in extension.

A subject with weak or paralyzed back extensor muscles

and strong hip extensor muscles cannot raise the trunk

in extension. The hip extensors, in their action to fix the

pelvis, are unopposed. The pelvis tilts posteriorly, and

the lumbar spine flexes.

In the next post, I will discuss about the back extensors test as well as glutes and quadratus lumborum. Stay tuned.