Median power frequency of the surface electromyogram and blood lactate concentration in incremental cycle ergometry

Robert Jansen, Wim Ament, Gijsbertus J. Verkerke, At L. Hof*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

31 Citations (Scopus)

Abstract

The electromyogram (EMG) median power frequency of the vastus lateralis and flexor digitorum superficialis muscles was measured in 12 subjects during cycle ergometry with step-wise increasing exercise intensities up to 100% of V(̇)O(2max). Blood lactate concentration was measured to investigate the relationship between changes in lactate concentration and shifts in the EMG median power frequency of exercising vastus lateralis and non-exercising flexor digitorum superficialis muscles. The results indicated that lactate concentration did not systematically affect median frequency: in spite of a considerable increase in blood lactate concentration, no systematic decrease of the median frequency during exercise was found, either for the vastus lateralis or for the flexor digitorum superficialis muscles. Instead of a decrease of the median frequency during exercise, as seen in isometrical protocols, an increase was seen in most subjects. An interesting finding was a decrease of the median frequency of vastus lateralis muscle during recovery in 8 subjects. The present findings showed that the relationship between EMG frequency decrease, lactate accumulation and fatigue, as observed in isometric protocols, cannot be simply applied to dynamic exercise.

Original languageEnglish
Pages (from-to)102-108
Number of pages7
JournalEuropean Journal of Applied Physiology and Occupational Physiology
Volume75
Issue number2
DOIs
Publication statusPublished - 1 Feb 1997
Externally publishedYes

Keywords

  • Dynamic contractions
  • Electromyogram
  • Flexor digitorum superficialis muscle
  • Median power frequency
  • Muscle fatigue
  • Vastus lateralis muscle

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