Postural Muscle Pain
Poor posture is related to musculoskeletal pain complaints with
findings of muscle imbalance and weakness.
Balanced posture observed from the side, finds the center of gravity
passing through the ear of the auditory canal, in the shoulder
through the acromion following the mid axillary line through the
midpoint of the iliac crest of the pelvis. This line continues
distantly in the lateral epicondyle of the femur to a point
approximately 2 cm posterior to the lateral condyle. This proper
alignment of posture places minimal strain on the muscles and
ligaments of the musculoskeletal structure.
A poor posture or slouch posture usually results in excessive lumbar
lordosis and excessive thoracic kyphosis and forward head
positioning. This slumped
posture mandates that the posterior cervical musculature must
increase its activity to maintain support for the head otherwise the
head would fall forward. The thoracolumbar “S” curve depends on
ligamentous tension to maintain its alignment.
In the seating position, a slumped posture required sustained
activity of the posterior cervical muscles to keep the head from
falling forward and places a strain on the spinal ligaments
supporting the curve of the spine.
One study evaluating poor sitting posture found that by placing
forward pressure in the fifth thoracic vertebrae in the sitting
position prevented spinal flexor muscle shortening.
One source of muscular strain to do is the result of skeletal
asymmetry from a lower leg length discrepancy. A lower leg length
discrepancy creates for a tilted pelvis requiring increased
contraction of the quadratus lumborum muscle to align the lumbar
spine over the pelvis. As the spine is tilted to one side, this tilt
requires further compensation in addition to the quadratus lumborum
muscle, which may recruit the neck muscles and upper shoulder
muscles such as the sternocleidomastoid and upper trapezial muscles.
There are few studies that looked at the origin of postural pain.
Summaries seem to indicate that it is not so much that the pain was
caused by muscle spasm as the primary source of pain was caused by
sustained tension on the joint capsules and ligaments.
Two studies exhibited the evidence of non-muscular spasm pain. One
study evaluated healthy female subjects, who were asked to sit in a
prolonged forward neck hanging down position until they could not
tolerate the pain. The subjects tolerances varied from 18 to 62
minutes utilizing a visual analog scale with pain levels have
ranging from 57 to 100. Surface EMG did showed some increase during
the first 3 minutes of this posture. The subjects reported the most
pain during the test found to have at least increase in muscle
contractile activity. Evidence of voluntary effort to reduce
discomfort by decreasing flexion was not associated with any
Another study assessed carrying a heavy load such as a suitcase in
one hand and supporting it with the arm hanging down the side for
several minutes. EMG activity was recorded in the deltoid and
supraspinatus muscle, but again eliminated the muscles as the source
of the pain and identified that the ligaments rather than the
muscles created the discomfort. Postural changes frequently occur
when there is a relationship between weakened and tight muscles.
Low back pain studies showed that these patients also had weak
gluteal muscles. Testing of multiple muscles from the low back
through the hamstrings identified a common set of imbalance
patterns. The imbalance patterns identified that at the pelvic level
there were tight or shortened hip flexors notably the iliopsoas and
tensor fascia lata muscles. Additionally, there were weak hip
extensors in the gluteal muscles. At the lumbar level, the trunk
flexors, which were the abdominal wall muscles were weak and the
trunk extensors, which were the erector spinae were tight. The
quadratus lumborum and hamstrings also tended to be tight. This
combination of weakness and tightness cause a muscular imbalance,
which resulted in a forward tilt of the pelvis creating increasing
lumbar lordosis and slightly increased hip flexion. This increased
in lumbar lordosis initiated a chain reaction that also produced
thoracic kyphosis and more superiorly cervical lordosis with the
head forward position.
In one study, it was found that patients with low back pain with
weak gluteal muscles, the contraction of the gluteus maximus was
In a comparable study of the cervical spine pain, it was found that
tight upper trapezial, sternocleidomastoid, levator scapulae, and
pectoralis muscles are the most common to be tight. Whereas these
are tight, the muscles that are weak and inhibited are the lower
stabilizers of the scapula being the serratus anterior, rhomboids,
middle and lower trapezial muscles, and the primary neck flexors of
the suprahyoid, mylohyoid, longus colli, and longus capitis muscles.
As a result, these patients when standing exhibited elevation and
protraction of the shoulder along with rotation and elevation of the
scapula resulting in variable winging of the scapula. This abnormal
scapular posture reduces the stability of the glenohumeral joint,
which required compensatory recruitment of the levator scapula and
upper trapezial muscles.
Other studies observed that in the head forward posture, findings of
tightened muscles of both pectoralis muscles, but specifically the
pectoralis major and then frequently the subscapularis muscle.
Multiple studies have shown that there are functionally related
muscles where one muscle may reflexively inhibit the activity of a
functionally related muscles in the same region. This has been shown
where the quadratus lumborum and gluteal muscles are functionally
related. When the gluteal muscles have weak recruitment, they were
improved by decreasing the trigger points of its functionally
related quadratus lumborum muscle. Therefore, if the quadratus
lumborum muscle is in spasm it therefore reduces firing of the
There is also relationship of the soleus muscle and the lumbar
paraspinal muscles on the ipsilateral side. Therefore,
inactivation of the right soleus trigger points relieved the spasm
of the right lumbar paraspinal muscles.
Another muscle group functionally related was the
sternocleidomastoid muscle having a relationship of the upper
trapezial and supraspinatus muscles.
In terms of relationship, the following were noted: Inactivation of
the sternocleidomastoid created an inactivated gastrocnemius muscle.
Inactivation of the upper trapezial, inactivated the rhomboid minor.
Inactivation of the lumbar paraspinals, inactivated the gluteus
maximus gastrocnemius and soleus. Inactivation of the quadratus
lumborum, inactivated the gluteus maximus.
Therefore, research confirms a direct relationship to functional
muscle groups and their effect on spinal elements which determines
Taras V. Kochno, M.D.
Board Certified in Physical Medicine & Rehabilitation
Copyright July 2, 2012