Muscle quality indices separately associate with joint-level power-related measures of the knee extensors in older males

Kosuke Hirata, Mari Ito, Yuta Nomura, Chiho Kawashima, Yuma Tsuchiya, Kosuke Ooba, Tsukasa Yoshida, Yosuke Yamada, Geoffrey A. Power, Neale A. Tillin, Ryota Akagi

Research output: Contribution to journalArticlepeer-review


Purpose: The purpose of this study was to investigate associations of muscle quality indices with joint-level power-related measures in the knee extensors of thirty-two older males (65–88 years). Methods: Muscle quality indices included: echo intensity, ratio of intracellular- to total water content (ICW/TW), and specific muscle strength. Echo intensity was acquired from the rectus femoris (EIRF) and vastus lateralis (EIVL) by ultrasonography. ICW/TW was computed from electrical resistance of the right thigh obtained by bioelectrical impedance spectroscopy. Specific muscle strength was determined as the normalized maximal voluntary isometric knee extension (MVIC) torque to estimated knee extensor volume. Isotonic maximal effort knee extensions with a load set to 20% MVIC torque were performed to obtain the knee extension power-related measures (peak power, rate of power development [RPD], and rate of velocity development [RVD]). Power and RPD were normalized to MVIC. Results: There were no significant correlations between muscle quality indices except between EIRF and EIVL (|r|≤ 0.253, P ≥ 0.162). EIRF was negatively correlated with normalized RPD and RVD (r ≤ − 0.361, P ≤ 0.050). ICW/TW was positively correlated with normalized peak power (r = 0.421, P = 0.020). Specific muscle strength was positively correlated with absolute peak power and RPD (r ≥ 0.452, P ≤ 0.012). Conclusion: Knee extension power-related measures were lower in participants with higher EI, lower ICW/TW, and lower specific muscle strength, but the muscle quality indices may be determined by independent physiological characteristics.

Original languageEnglish
JournalEuropean Journal of Applied Physiology
Publication statusPublished - 2022 Oct


  • Bioelectrical impedance spectroscopy
  • Echo intensity
  • Intracellular water
  • Rate of power development
  • Rate of velocity development
  • Specific muscle strength

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Public Health, Environmental and Occupational Health
  • Physiology (medical)


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