Relative differences in strength and power from slow to fast isokinetic velocities may reflect dynapenia

Nathaniel D.M. Jenkins, Terry J. Housh, Ty B. Palmer, Kristen C. Cochrane, Haley C. Bergstrom, Glen O. Johnson, Richard J. Schmidt, Joel T. Cramer

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Introduction: We compared absolute and normalized values for peak torque (PT), mean power (MP), rate of velocity development, and electromyography (EMG) amplitude during maximal isometric and concentric isokinetic leg extension muscle actions, as well as the %decrease in PT and %increase in MP from 1.05 to 3.14 rad·s-1 in younger versus older men. Methods: Measurements were performed twice for reliability. Isokinetic measurements were normalized to the isometric muscle actions. Results: Absolute isometric PT, isokinetic PT and MP, and EMG amplitudes at 1.05 and 3.14 rad·s-1 were greater in the younger men, although normalizing to isometric PT eliminated the age differences. The older men exhibited greater %decrease in PT (37.2% vs. 31.3%) and lower %increase in MP (87.6% vs. 126.4%) regardless of normalization. Conclusions: Normalization eliminated absolute differences in isokinetic strength and power, but the relative differences from slow to fast velocities may reflect dynapenia characterized by age-related decreases in fast-twitch fiber function.

Original languageEnglish (US)
Pages (from-to)120-130
Number of pages11
JournalMuscle and Nerve
Volume52
Issue number1
DOIs
StatePublished - Jul 1 2015

Keywords

  • EMG
  • Normalization
  • Power-velocity
  • Reliability
  • Sarcopenia
  • Torque-velocity

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)

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  • Cite this

    Jenkins, N. D. M., Housh, T. J., Palmer, T. B., Cochrane, K. C., Bergstrom, H. C., Johnson, G. O., Schmidt, R. J., & Cramer, J. T. (2015). Relative differences in strength and power from slow to fast isokinetic velocities may reflect dynapenia. Muscle and Nerve, 52(1), 120-130. https://doi.org/10.1002/mus.24505