What is meant by a “Muscle Imbalance”?

When humans move we require a balance of muscle strength and length between our opposing muscle groups that surround any joint. We have a certain amount of force between opposing muscles that are necessary to keep our bones in the correct position to ensure the joint is well centered or in line during a particular movement. This action is considered muscle balance where as a “muscle imbalance” happens when opposing muscle groups cause different directions of tension either due to tightness and or a weakness in the opposing muscles. Therefore when it is too tight the joints will move in that particular direction since it offers the least resistance for it. If we look for instance at the knee joint we would see the quadriceps and hamstrings actually perform opposite movements. If we had an imbalance between these two we would alternately see stress placed on the knee joint. Therefore if the hamstring was tight it would not allow the knee to glide in a normal fashion which would place undue stress on the quadriceps and the patella itself. When we look at imbalances we are normally referring to either muscles that are either side by side, left against right, or back against front which you will often hear referred to as the antagonist verse the agonist. We see mainly musculoskeletal pain in relation to the front to back around a particular joint. The main two causes of imbalances are biomechanical which are normally caused by repeated movements or bad positioning generally. The second cause can be in fact a neuromuscular imbalance which is due to a predisposition where the person involved has either tightness or a weakness that can evolve from birth. This is known as a TONIC (prone to tightness) or “PHASIC” (prone to weakness). Those muscles prone to TONIC (TIGHTNESS) are: Iliopsoas,Tensor Fascia Lata, piriformis, erector-spinae (lumbar), suboccipital muscles, quadrates lumborum, pec major/and minor, upper traps, levator scapulae, our scalene, sternovleidomastoid, rectus femoris, Gastroc-Soleus, hip adductors and hamstrings. Those more likely to subject to “PHASIC” are: Tibialis Anterior, Peroneals, vastus medialis, vastus lateralis, glut max, glut med, transverses abdominus, multifidus, rectus abominus, abdominal obliques, serratus anterior, rhomboids, lower and mid traps and our deep neck flexors.

According to Dr. Janda, there are 3 specific muscle imbalance syndromes associated with chronic musculoskeletal pain they are listed below:


“Upper-Crossed Syndrome (UCS) is also referred to as proximal or shoulder girdle crossed syndrome. In UCS, tightness of the upper trapezius and levator scapula on the dorsal side crosses with tightness of the pectoralis major and minor. Weakness of the deep cervical flexors ventrally crosses with weakness of the middle and lower trapezius. This pattern of imbalance creates joint dysfunction, particularly at the atlanto-occipital joint, C4-C5 segment, cervicothoracic joint, glenohumeral joint, and T4-T5 segment. Janda noted that these focal areas of stress within the spine correspond to transitional zones in which neighboring vertebrae change in morphology. Specific postural changes are seen in UCS, including forward head posture, increased cervical lordosis and thoracic kyphosis, elevated and protracted shoulders, and rotation or abduction and winging of the scapulae. These postural changes decrease glenohumeral stability as the glenoid fossa becomes more vertical due to serratus anterior weakness leading to abduction, rotation, and winging of the scapulae. This loss of stability requires the levator scapula and upper trapezius to increase activation to maintain glenohumeral centration (Janda 1988).

Lower-Crossed Syndrome (LCS) is also referred to as distal or pelvic crossed syndrome. In LCS, tightness of the thoracolumbar extensors on the dorsal side crosses with tightness of the iliopsoas and rectus femoris. Weakness of the deep abdominal muscles ventrally crosses with weakness of the gluteus maximus and medius. This pattern of imbalance creates joint dysfunction, particularly at the L4-L5 and L5-S1 segments, SI joint, and hip joint. Specific postural changes seen in LCS include anterior pelvic tilt, increased lumbar lordosis, lateral lumbar shift, lateral leg rotation, and knee hyperextension. If the lordosis is deep and short, then imbalance is predominantly in the pelvic muscles; if the lordosis is shallow and extends into the thoracic area, then imbalance predominates in the trunk muscles (Janda 1987).

Janda’s Layer syndrome (also referred to as “Stratification Syndrome”) is a combination of both upper and lower crossed syndromes. There is marked impairment of motor regulation that has increased over a period of time. Patients with layer syndrome have a poorer prognosis than those with isolated UCS or LCS due to the long-standing dysfunction. This pattern is often seen in older adults and in patients suffering unsuccessful surgery for herniated nucleus pulposus (HNP).

It does take a very qualified person to work with these muscle imbalances and not something your local personal trainer is normally qualified in. If you believe you may be suffering from any of these imbalances I suggest you consult with either a good Physio or an Exercise Physiologist. Many people are unaware that they have these issues and it could be (in some cases) that your trainer is contributing to further damage and pain you may be experiencing.

By: John Hart
Master’s In Education” (Disability/Rehab) Newcastle University Australia
“Grad Cert Education” Newcastle University Australia
“Diploma Fitness/Recreation”
“Diploma of Sport and Recreation”
“Cert 4 Personal Training”
“Level 1 Strength and Conditioning Coach”
Member of ASCA (Australian Strength and Conditioning Association)

One Response to “What is meant by a “Muscle Imbalance”?”

  1. Jeff Parker October 8, 2012 at 12:21 pm Permalink

    I haven’t heard those terms before regarding the syndromes of the muscle imbalances. Your article was enlightening and enjoyable.

    I’m now going to have to read up more on Dr. Janda =)

Leave a Reply