This two part blog considers the relevance and application of models of muscle classification and considers contemporary interpretations and applications of the classic concept of muscle imbalance.
Managing the complexity
Movement is complex. The multitude of interactions between the varying systems of the body responsible for the generation of human movement can be as bewildering as they are beguiling. For those tasked with the maintenance of a pain free state or with enhancing performance, the small window of contact time with a patient or client can feel insufficient to make real change. Where, within the multiple and simultaneous processes at play, does risk to performance and the injury free state lie and how are they to be addressed?
Models to manage this movement complexity can assist.
Skills of movement management
The employment of a systematic model to manage this complexity has been the aim and eventual successful outcome of the development of The Performance Matrix; a movement system that comes as the fruition of over a decade of research and design. This system allows for the testing and retraining of movement deficits linked to injury risk and compromised performance; a structured process to make sense of function’s complexity.
Effective operation of the tool requires a range of skills, such as the observation of movement quality during testing, in addition to the ability to interpret the movement analysis report the testing system generates, prior to the teaching of movement in subsequent retraining.
Muscle classification - models to assist clarity
Increasing the efficiency of testing, interpretation of the testing report and application of movement retraining, is a strong underpinning knowledge of muscle classifications. Such models of muscle classification first appeared in the literature over 40 years ago, first proposed by Rood (Goff, 1972), partitioning muscles into stabiliser or mobiliser groupings, a conceptual framework further refined by Janda (1985) and Sarhmann (1992, 2000).
In tandem to these respected movement focussed authors, Bergmark (1989) described the concept of local and global muscles, a delineation based on muscle architecture, muscles’ deep or superficial arrangement on the trunk and their torque/force producing potential. Concatenating and further expanding upon the work of previous authors, Comerford and Mottram (2001) forwarded a three part model, now underpinning The Performance Matrix system, allowing muscles and their roles to be listed as;
- Local stabiliser
- Global stabiliser
- Global mobiliser
Muscles acting in the role of a local stabiliser (1) would be characterised by possessing the ability to;
- supply continuous activity throughout movement, independent of the direction of that movement
- increase segmental stiffness to limit translation
The local stability role of muscle function is one demanding minimal change in muscle length, and therefore approximating to isometric contractions, responsible for limiting accessory movements as opposed to the production or management of physiological joint range (flexion, extension…)
The global stabiliser (2) role of muscles calls upon structures to;
- generate force to limit or decelerate range of motion (especially rotation)
- display sufficient force production during eccentric lengthening
Unlike the local stabiliser role of muscles, this function is direction of activity dependent (hip flexion will elicit the involvement of different global stabilisers compared to hip extension) and non-continuous in nature (periods of relative silence prior to onset). Architecturally, global stabilisers are profiled as mono-articular in nature, with a diagonal arrangement across the joint structures with which they directly interact. In the presence of pain, these structures are typically seen to experience a process of inhibition, therefore contributing in reduced amounts to movement management.
The global mobilisers (3) role of muscles calls upon structures to;
- generate torque to produce range of motion (especially in bilateral, sagittal plane actions)
- concentric actions, such as required for accelerative, rapid shortening
- absorb shock
Again, distinguishing global from local roles, global mobilisers’ activity is direction of activity dependent and non-continuous in profile. Architecturally, mobilisers are seen to be multi-articular in nature, capable of influencing multiple regions, in a process of force production and energy transfer. Further segmenting global mobiliser from global stabiliser, the presence of pain is seen to produce an increase in contribution from mobiliser structures, especially evident during activities deemed as sustained, postural or low intensity.
Take a look at this video where KC's Mark Comerford discusses Muscle Classification and Movement Function Sub-Grouping
Certain musculature, such as infraspinatus/teres minor, appear to play all three roles, a useful reminder of the body’s highly adaptable qualities. A useful way to consider such multi-purpose structures is to imagine a computer device loaded with 3 different types of software. Such potential, to carry out many roles, will be explored further in part 2.
Armed with the systemised structure the muscle classification supplies allows the complexity of function to be broken down and evaluated prior to its reassembly. The second part of this blog considers the employment of this model in addition to the body’s use of muscle synergies in both health and dysfunction.
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.