Difference in fascicle behaviors between superficial and deep quadriceps muscles during isometric contractions.
BACKGROUND
In this study we examined changes in fascicle length and pennation of vastus intermedius (VI) and vastus lateralis (VL) from rest to isometric contraction.


METHODS
Fourteen healthy men performed submaximal (30% and 50% of maximal voluntary contraction; MVC) isometric knee extensions at 60° and 110° knee flexion (0° = full extension). Panoramic images of VL and VI were obtained at rest and during contractions to measure fascicle length and pennation using extended field-of-view ultrasonography, after confirmation that the technique could be used reliably during sustained submaximal isometric contractions.


RESULTS
The relative change in fascicle length from rest to 50% MVC was greater in VI than VL at 110° (P < 0.05). Pennation increased during contraction at 60° for VL (P < 0.05), but not for VI.


CONCLUSIONS
Muscle-dependent fascicle behaviors were observed during contraction. These findings may provide a mechanistic underpinning for differences in sarcomere length changes, relative force contribution, and blood flow during contraction.
Graduate School of Education and Human Development, Nagoya University, Furo, Chikusa, Nagoya, Aichi, 464-8601, Japan.|Centre for Exercise and Sport Science Research, School of Exercise and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia.
Ryosuke
R
Ando
Centre for Exercise and Sport Science Research, School of Exercise and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia.
Kazunori
K
Nosaka
Centre for Exercise and Sport Science Research, School of Exercise and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia.
Takayuki
T
Inami
Graduate School of Education and Human Development, Nagoya University, Furo, Chikusa, Nagoya, Aichi, 464-8601, Japan.
Aya
A
Tomita
School of International Liberal Studies, Chukyo University, Nagoya, Japan.
Kohei
K
Watanabe
Centre for Exercise and Sport Science Research, School of Exercise and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia.
Anthony J
AJ
Blazevich
Graduate School of Education and Human Development, Nagoya University, Furo, Chikusa, Nagoya, Aichi, 464-8601, Japan.|Research Center of Health, Physical Fitness & Sports, Nagoya University, Nagoya, Japan.
Hiroshi
H
Akima
D000328:Adult; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography; D055815:Young Adult
fascicle length; knee joint angle; pennation; ultrasonography; vastus intermedius; vastus lateralis