Determination of fascicle length and pennation in a contracting human muscle in vivo

Tetsuo Fukunaga, Yoshiho Ichinose, Masamitsu Ito, Yasuo Kawakami*, Senshi Fukashiro

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

334 Citations (Scopus)


We have developed a technique to determine fascicle length in human vastus lateralis muscle in vivo by using ultrasonography. When the subjects had the knee fully extended passively from a position of 110°flexion (relaxed condition), the fascicle length decreased from 133 to 97 mm on average. During static contractions at 10% of maximal voluntary contraction strength (tensed condition), fascicle shortening was more pronounced (from 126 to 67 mm), especially when the knee was closer to full extension. Similarly, as the knee was extended, the angle of pennation (fascicle angle, defined as the angle between fascicles and aponeurosis) increased (relaxed, from 14 to 18°; tensed, from 14 to 21°), and a greater increase in the pennation angle was observed in the tensed than in the relaxed condition when the knee was close to extension (<40°). We conclude that there are differences in fascicle lengths and pennation angles when the muscle is in a relaxed and isometrically tensed conditions and that the differences are affected by joint angles, at least at the submaximal contraction level.

Original languageEnglish
Pages (from-to)354-358
Number of pages5
JournalJournal of Applied Physiology
Issue number1
Publication statusPublished - 1997 Jan
Externally publishedYes


  • muscle contraction
  • pennation angle
  • ultrasound
  • vastus lateralis muscle

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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