Spatial dependency of trapezius muscle activity during repetitive shoulder flexion

Deborah Falla, D Farina, T Graven-Nielsen

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

The purpose of this study was to explore changes in spatial muscle activation within the three divisions of the trapezius muscle during a dynamic, cyclic task of the upper limb. Surface EMG signals were detected from thirteen healthy subjects from the upper, middle and lower divisions of the trapezius muscle at multiple electrode sites in the cephalad-caudal direction during a repetitive shoulder flexion task. Initial values and rate of change of average rectified value (ARV) and of instantaneous mean power spectral frequency (iMNF) were estimated at 45 degrees , 90 degrees and 120 degrees of shoulder flexion throughout the 5-min task. The location of the electrodes had a significant effect on initial EMG ARV for both the upper and middle division of the trapezius muscle (P<0.05). Both the rate of change and normalized rate of change of ARV were greatest for the most cranial muscle fibers of the upper division (P<0.05). Initial values and rates of change of iMNF were also affected by electrode location for the upper and lower divisions of the trapezius muscle (P<0.05). These results demonstrate that muscle activity and its changes over time depend on position within the three divisions of the trapezius muscle during a dynamic, cyclic task of the upper limb. This suggests non-uniform muscle fiber distribution and/or recruitment. The results also highlight the importance of multiple recording sites when investigating trapezius muscle function in dynamic tasks.

Original languageEnglish
Pages (from-to)299-306
Number of pages8
JournalJournal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology
Volume17
Issue number3
DOIs
Publication statusPublished - Jun 2007

Keywords

  • Adult
  • Analysis of Variance
  • Electromyography
  • Female
  • Humans
  • Male
  • Movement
  • Muscle, Skeletal
  • Range of Motion, Articular
  • Shoulder Joint
  • Journal Article
  • Research Support, Non-U.S. Gov't

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