The relative position of EDL muscle affects the length of sarcomeres within muscle fibers: experimental results and finite-element modeling.
BACKGROUND
Effects of extramuscular connective tissues on muscle force (experimentally measured) and lengths of sarcomeres (modeled) were investigated in rat. It was hypothesized that changes of muscle-relative position affect the distribution of lengths of sarcomeres within muscle fibers.


METHODS
The position of extensor digitorum longus muscle (EDL) relative to intact extramuscular connective tissues of the anterior crural compartment was manipulated without changing its muscle-tendon complex length.


RESULTS
Significant effects of EDL muscle relative position on proximal and distal EDL forces were found, indicating changes of extramuscular myofascial force transmission. EDL isometric force exerted at its proximal and distal tendons differed significantly. Finite-element modeling showed that the distribution of lengths of sarcomeres is altered by changes of muscle-relative position.


CONCLUSIONS
It is concluded that forces exerted on a muscle via extramuscular myofascial pathways augment distributions of lengths of sarcomeres within that muscle.
Maas
Huub
H
Instituut voor Fundamentele en Klinische Bewegingswetenschappen, Faculteit Bewegingswetenschappen, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands.
Baan
Guus C
GC
Huijing
Peter A
PA
Yucesoy
Can A
CA
Koopman
Bart H
BH
Grootenboer
Henk J
HJ
D000818:Animals; D016764:Cell Polarity / Q000502:physiology*; D003198:Computer Simulation; D020342:Finite Element Analysis; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012518:Sarcomeres / Q000502:physiology*; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013643:Tarsus, Animal / Q000502:physiology