Medical & Biological Engineering & Computing

, Volume 57, Issue 3, pp 703–713 | Cite as

Time-frequency coherence of categorized sEMG data during dynamic contractions of biceps, triceps, and brachioradialis as an approach for spasticity detection

  • Sebastian BeckerEmail author
  • S. C. F. A. von Werder
  • A.-K. Lassek
  • C. Disselhorst-Klug
Original Article


The assessment of muscular interactions between biceps, triceps, and brachioradialis can be used as an approach for the detection of spasticity in the upper limbs. A crucial prerequisite for the aforementioned validation of muscular interactions is the calculation of time frequencies due to the non-stationary characteristics of electromyographic (EMG) signals and thus the estimation of coherences. Adding biomechanical parameters increases the validity of the assessment process and simplifies the comparison of EMG data as a result of categorization. In this numerical-experimental study, a method will be introduced by using the smoothed pseudo Wigner-Ville distribution and a categorization algorithm to estimate and categorize coherences between biceps, triceps, and brachioradialis during dynamic contractions. The categorization will be performed according to the type of contraction, external load, joint angle, and angular velocity and will be used to assess 10 healthy subjects and 6 patients with spasticity. Generally, the introduced method shows the velocity dependence of coherence during spasticity in extension movements as well as much stronger muscular co-activation between triceps, biceps, and brachioradialis in spastic patients in comparison to healthy subjects. Furthermore, the influence of variables e.g. as joint angle, angular velocities, and type of contraction on the coherence is quantified.


Time-frequency analysis Coherence Categorization sEMG Spasticity 


Funding information

The authors were financially supported for parts of the work by the Federal Ministry of Education and Research (BMBF) of Germany within the framework of inRehaRob.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants including in this study.


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Copyright information

© International Federation for Medical and Biological Engineering 2018

Authors and Affiliations

  • Sebastian Becker
    • 1
    Email author
  • S. C. F. A. von Werder
    • 1
  • A.-K. Lassek
    • 1
  • C. Disselhorst-Klug
    • 1
  1. 1.Department of Rehabilitation and Prevention Engineering, Institute of Applied Medical EngineeringRWTH UniversityAachenGermany

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