Muscle Classification and Muscle Imbalance Part 2

The first part of this blog discussed the use of muscle classification models so as to aid the management of human movement. A thorough understanding of the model proposed by Comerford & Mottram (2001), is seen to significantly increase the effectiveness of the use of The Performance Matrix movement management system.

Many ways to move

The roles of the body’s muscles, local or global, stabiliser or mobiliser, supply many options as to how a task may be achieved. Indeed, in everyday life, both simple and complex tasks will be performed in different ways, by different people.

Which way is best? The question of ‘what is the best way to move?’ might just be best answered, ‘with choices and options, as opposed to only in one way’.

A body of learning and problem solving– the movement machine

The possession of a wide range of functional and interactive units (muscles), that span the entirety of the body, supplies the individual with a highly versatile, adaptable tool (the body), allowing the realisation of both intention and instinct.

This is highly beneficial, as challenges can be met and overcome, yet, the daily necessities of function can sometimes demand structures architecturally or neurophysiologically advantaged towards some actions to be employed for others. This is normal, such as in the presence of fatigue. When people get tired, they use different movement strategies, to keep going. However, whilst ensuring a task may still attempted and achieved in the short term, the body’s ability to ‘find a solution’ may come at a long term cost. For example, always moving as if fatigued, and therefore employing back up strategies usually saved for times of necessity as a first and only choice, seems to imply other strategies may be absent. Also, always moving in the same way, without the ability to vary ‘the how’ in the achievement of ‘the what’ may be a significant risk for overuse injuries. If we know how and where to look, we can find the strategies that are lost and restore them. Aiding this process is a consideration of muscle synergies and the balance between global mobilisers and stabilisers.

Muscle synergists- isofunctional units of movement…and choice

Within any one movement at a joint region, numerous muscles are seen to contribute to concentric, eccentric or isometric force production. Those muscles producing force in the same contraction profile (i.e. concentric), so as to produce a movement can be filed under the heading of ‘synergists’. The same classification can be applied to eccentric or isometric contractions. In the next instant, any one grouping of synergists may be converted in to antagonists, as their combined role in one plane now becomes an antagonistic role in another; the medial and lateral hamstrings are sagittal plane synergists, but antagonists in the transverse plane.

Within synergistic groupings, contributions of any one particular muscle can vary depending on a multitude of factors to include, the intensity of the activity, the presence of fatigue, previous injury, training history, in addition to others. Applying the global stabiliser, global mobiliser classification to this situation allows a pattern to emerge of which structures are high likely to be contribute less and those which may contribute more. In the presence of pain and fatigue, there appears to be an increasing employment of the multi-articular global mobilisers and lessening of the involvement of their global stabiliser synergists. There is an imbalance in contribution, as one does more, and the other does less. Again, this can be a normal response when evident in the short term, such as in the presence of fatigue; it is a strategy to keep going. But, if this strategy is an individual’s normal, background state (non-fatigued/no pain) there is inefficiency, in terms of the architectural and neurophysiological qualities of the mobilisers and stabilisers. Additionally, it would imply movement options have been lost; if we are already employing our back-up state, where do we go from here when we are actually fatigued?

Synergistic imbalances and using the model

Assessing the synergistic contributions to an activity, the balance between mobiliser and stabiliser employment, supplies insight on the individual’s current state; are they at a place in which they have choices, and still possess options once fatigue or pain emerges? Or not?

Testing movement with The Performance Matrix requires the ability to identify the kinematic markers that infer which synergies are out of balance. Spotting the ‘calling card’ of the inefficient mono-articular structures is a skill of observation, palpation and the application of muscle classifications system. A knowledge of the muscle classifications system also allows the report this process generates to be used for clinical or synergistic reasoning- which stabilisers need targeting, which mobilisers need calming down.

Once exercises are selected, synergies can be rebalanced. Movement options can be restored, back up strategies are now accessible in the reserve tank as opposed to always on call. We heading back to a place of choice, a place of an optimal number of movement strategies.

Take home message

Models of muscle classification aid the management of movement by partitioning musculature into workable groupings based on a number of characteristics. Within synergistic groupings, contributions are seen to alter depending on a range of factors. Whilst this ability supplies huge variety to ongoing task achievement, assessing muscles synergies informs on the individual’s current strategy status; one in which they possess back up strategies or one in which they are operating on the reserve tank mode.

The Performance Matrix offers a complete movement management system to address this complexity.  To find out more visit The Performance Matrix website

Visit the KC Buzz section of he Kinetic Control website to see KC’s Mark Comerford discuss Muscle Characterisation



  • Bergmark, A. (1989). Stability of the lumbar spine. A study in mechanical engineering. Acta Orthopaedica Scandinavica. 230(60): 20-24.
  • Comerford, M., & Mottram, S. (2001). Movement and stability dysfunction – contemporary developments. Manual Therapy 6(1): 15–26.
  • Goff, B. (1972). The application of recent advances in neurophysiology to Miss R Rood’s concept of neuromuscular facilitation. Physiotherapy 58:2 409-415.
  • Janda, V. (1985). Pain in the locomotor system – A broad approach. In Glasgow et al. (eds.) Aspects of Manipulative Therapy. Churchill Livingstone: 148-151.
  • Sahrmann, S. A. (2000). Diagnosis and Treatment of Movement Impairment Syndromes. Mosby, USA. In Press.
  • Sahrmann, S.A. (1992). Posture and muscle imbalance. Faulty lumbar-pelvic alignment and associated musculoskeletal pain syndromes. Orthopedic Division Review. Nov/Dec. 13-20.