Clinical Model to the Analysis of Synergy Pattern Changes of Back Muscles and its Relationship with the Occurrence of Fatigue

Armin HakKak Moghaddam Torbati*, Ehsan Tahami, Hamid Reza Kobravi
Department of Biomedical Engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran

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© 2018 Torbati et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of biomedical engineering, Mashhad Branch, Islamic Azad University, Mashhad, Iran; Tel: 989153161523; E-mail:



Right sitting not only leads to flatness of the lumbar spine and waistline, it also causes other problems for health. The curved body pushes into lungs and breathing will be problematic.


The main purpose of this study was investigating changing procedure of lumber muscles patterns and its relationship with the occurrence of fatigue.


Participants were ten male with average age 24 ± 1. Firstly, the process of fatigue during sitting was observed by mid-frequency index. For performing the necessary analysis, the 10-second window of time was used. The 15 minutes of time trial was divided into 3 sub-terms. Each sub-term was investigated separately. The sub-terms contain: The beginning of record until the 90th second, from the 90th second to the 600th second and from the 600th second to the 900th second.


Results showed that in each subject there were synergy patterns in both of the first and the second sub-terms. Maximum error between basis vectors in all of the subjects were 0.87 and 0.79 respectively and standard deviations were 5 and 10 respectively (Mean square error index). In some participants, there were not any synergy patterns in the third sub-term (minimum error between basis vectors in all of the subjects was 18 and standard deviation was 7.5) while in other participants, their muscles still followed special synergy patterns (maximum error between basis vectors in all of the subjects was 0.98 standard deviation was 7.5).


Comparing the synergy patterns between different participants has determined that the synergy patterns were the same only in the first sub-term.

Keywords: Electromyogram signal, Fatigue, HALS algorithm, Motor control, Synergy, Right sitting.