Document Type : Full Research Paper


1 Department ofMechanical Engineering, Sharif University of Technology

2 Arthritis and Musculoskeletal Research Group, University of Sydney



Selection of muscle activation pattern to reach a specific goal by considering the complexities of neuromuscular system and the way it overcomes these complications, is of researchers􀂶interest in motor control. One proposed solutionfor resolving thesecomplexities is the concept of simple module (synergies) that the combination of them leads to more complex activities. In the present work, the existence and arrangement of synergies in the lumbar spine are proved. For this purpose, a model with 18-muscles in level L4-L5 is utilized in the static condition. In order to obtaina muscular and stability synergies, muscle activation, which are obtained by exerting moments in 2D and 3D spaces and angular stiffness to the model,are used. The results show that six muscular synergies suffice to be able to reach any point in the moment space. Also, three stability synergies can reconstruct a part of joint angular stiffness space. In addition, the obtained muscular synergies are robust against changes in the amplitude of exerted moment. In this study, it is shown that one can generates any task involves producing determined moment and angular stiffness in the joint, by combining muscular and stability synergies together.


Main Subjects

[1]     Andersson GBJ, “The epidemiology of spinal disorders, In: Frymoyer JW, (Ed.), The adult spine: principles and practice, 2nd ed, Philadelphia: Lippincott-Raven”, p.p. 93–141, 1997.
[2]     Walker BF, “The prevalence of low back pain: a systematic review of the literature from 1966 to 1998” J Spinal Disord, Vol. 13-3, p.p. 205-217, 2000.
[3]     Chopra A, Abdel-Nasser A. “Epidemiology of rheumatic musculoskeletal disorders in the developing world” Best PractClinRheumatol, Vol. 22, p.p. 583-601, 2008.
[4]     Dagenais S, Caro J, Haldeman S., “A systematic review of low back pain cost of illness in the United States and internationally” Spine J, Vol. 8, p.p. 8-20, 2008.
[5]     Davatchi F, TehraniBanihashemi A, Gholami J, et al. “The prevalence of musculoskeletal complaints in a rural area in Iran: a WHO ILAR COPCORD study (stage 1, rural study) in Iran” ClinRheumatol, Vol. 28, p.p. 1267-74, 2009.
[6]     Naghavi M, Abolhassani F, Pourmalek F, et al., “The burden of disease and injury in Iran 2003” Popul Health Metr, Vol. 7-9, 2009.
[7]     E. Bizzi, A. D’avella, P. Saltiel, And M. Tresch,”Modular Organization of Spinal Motor Systems”, The Neuroscientist, Vol. 8, Num. 5, 2002
[8]     LH, Ting and JM, Macpherson.,“A Limited Set of Muscle Synergies for Force Control During a Postural Task.” J Neurophysiol, 2005, Vol. 93.
[9]     Gelsy Torres-Oviedo, Jane M. Macphersonand Lena H. Ting,“Muscle Synergy Organization Is Robust Across a Variety of Postural Perturbations.”., J Neurophysiol, 2006.
[10] Matthew C. Tresch, Vincent C. K. Cheung and Andrea d'Avella,“Matrix Factorization Algorithms for the Identification of Muscle Synergies: Evaluation on Simulated and Experimental Data Sets.”JNeurophysiol, 2006, Vol. 95.
[11] Michael W. Berry, Murray Browne, Amy N Langville, V. Paul Pauca, Robert J. Plemmons, “Algorithms and applications for approximate nonnegative matrix factorization. “, Computational Statistics and Data Analysis , 2006, Vol. 52.
[12] E.Rashedi, et al, “How does the central nervous system address the kinetic redundancy in the lumbar spine? Three-dimensional isometric exertions with 18 Hill-model-based muscle fascicles at the L4–L5 level .”, Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, 2010 , Vol. 224.
[13] A.d'Avella, P. Saltiel and E. Bizzi. ,“Combinations of muscle synergies in the construction of a natural motor behavior.”, Nature Neuroscience, 2003, Vol. 6.
[14] Cheung, Vincent C. K., et al. “Central and  Sensory Contributions to the Activation and Organization of Muscle Synergies during Natural Motor Behaviors.”, The Journal of Neuroscience, 2005, Vol. 25. Num. 27
[15] d’Avella, Andrea and Bizzi, Emilio.,“Shared and specific muscle synergies in natural motor behaviors.” Proceedings of the National Academy of Sciences, 2005, Vol. 102.
[16] Yong Hu Mak, J.N.F. Lu, W.W. Cheung, K.M.C. Luk, K.D.K. ,”Visualization of Lumbar Muscle Contraction Synergy using Surface Electrography(sEMG) Streaming Topography.” San Francisco, CA, USA : International Conference of the IEEE , 2004, Vol. 1.