Determination of fascicle length and pennation in a contracting
human muscle in vivo.
Fukunaga, Tetsuo, Yoshiho Ichinose, Masamitsu Ito, Yasuo Kawakami, and
Senshi Fukashiro.
Department of Life Sciences, The University of Tokyo, Komaba 3-8-1,
Meguro, Tokyo 153, Japan
APStracts 3:0448A, 1996.
We have developed a technique to determine fascicle length in human
vastus lateralis muscle in vivo using ultrasonography. When the
subjects had the knee fully extended passively from a position of
110[square root] 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 (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, 14 to
18[square root]; tensed, 14 to 21[square root]) 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[square root]). It was concluded that there are
differences in fascicle lengths and pennation angles when the muscle
is in a relaxed and isometrically tensed conditions, and that they
are affected by joint angles at least at the submaximal contraction
level.
Received 16 January 1996; accepted in final form 10 September
1996.
APS Manuscript Number A39-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996