2C2-06 Measurement of muscular fiber length in human using of ultrasound : Visco-elastic property of tibialis anterior

Force enhancement following muscle stretching and force depression following muscle shortening are well-accepted properties of skeletal muscle contraction. However, the factors contributing to force enhancement/depression remain a matter of debate. In addition to factors on the fiber or sarcomere level, fiber length and angle of pennation affect the force during voluntary isometric contractions in whole muscles. Therefore, we hypothesized that differences in fiber lengths and angles of pennation between force-enhanced/depressed and reference states may contribute to force enhancement/depression during voluntary contractions. The purpose of this study was to test this hypothesis. Twelve subjects participated in this study, and force enhancement/depression was measured in human tibialis anterior. Fiber lengths and angles of pennation were quantified using ultrasound imaging. Neither fiber lengths nor angles of pennation were found to differ between the isometric reference contractions and any of the force-enhanced or force-depressed conditions. Therefore, we rejected our hypothesis and concluded that differences in fiber lengths or angles of pennation do not contribute to the observed force enhancement/depression in human tibialis anterior, and speculate that this result is likely true for other muscles too.

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Transverse Strain of Aponeurosis in Human Tibialis Anterior Muscle at Rest and during Contraction at Different Joint Angles

Journal of Applied Biomechanics ◽

10.1123/jab.19.1.39 ◽

2003 ◽

Vol 19 (1) ◽

pp. 39-48 ◽

Cited By ~ 6

Author(s):

Tetsuro Muraoka ◽

Tadashi Muramatsu ◽

Hiroaki Kanehisa ◽

Tetsuo Fukunaga

Keyword(s):

Muscle Fiber ◽

Resting State ◽

Tibialis Anterior ◽

Fiber Length ◽

Tibialis Anterior Muscle ◽

Transverse Strain ◽

Relative Width ◽

Significant Difference ◽

Human Tibialis Anterior Muscle

The aim of the present study was to determine the transverse strain of aponeuroses in human tibialis anterior muscle (TA) in vivo and to clarify the influence of muscle fiber length and state of contraction on the transverse strain. Sagittal and horizontal images of TA were taken in seven men and one woman at ankle angles of –20° (dorsiflexed direction), 0° (neutral anatomic position), and 45° (plantar-flexed direction) both at rest and during submaximal dorsiflexion contraction (20 Nm: 0° and 45°; 10 Nm: –20°) using B-mode ultrasonography. The width of the TA central aponeurosis changed from 21.7 ± 1.0 (mean ±SE) to 25.5 ± 1.1 mm when muscle fiber length changed from 91.0 ± 3.5 (45° in the resting state) to 55.1 ± 3.2 mm (–20° in the active state). The transverse strain of the TA central aponeurosis, which was change in relative width compared with the width at 45° in the resting state, increased when the muscle fiber length decreased. The transverse strain of the TA central aponeurosis was directly proportional to the muscle fiber length to the –1/2 power in both resting and active states (R= 0.81 and 0.74,p< 0.05 for both), and there was no significant difference (p< 0.05) between correlation coefficients and regression slopes for resting and active states. The findings suggest that the transverse strain of the TA central aponeurosis was closely related to muscle fiber length and that the transverse strain of the aponeurosis should be considered for accurate 3-D muscle modeling.

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Age does not influence muscle fiber length adaptation to increased excursion

Journal of Applied Physiology ◽

10.1152/jappl.2001.91.6.2466 ◽

2001 ◽

Vol 91 (6) ◽

pp. 2466-2470 ◽

Cited By ~ 6

Author(s):

Thomas J. Burkholder

Keyword(s):

Muscle Fiber ◽

Tibialis Anterior ◽

Fiber Length ◽

Tibialis Anterior Muscle ◽

Age Groups ◽

Muscle Length ◽

Adult Rats ◽

Cross Sectional ◽

Muscle Excursion ◽

Sarcomere Number

Muscle fiber length adaptation to static stretch or shortening depends on age, with sarcomere addition in young muscle being dependent on mobility. Series sarcomere number can also increase in young animals in response to increased muscle excursion, but it is not clear whether adult muscles respond similarly. The ankle flexor retinaculum was transected in neonatal and adult rats to increase tibialis anterior muscle excursion. Sarcomere number in tibialis anterior was determined after 8 wk of adaptation. Muscle moment arm and excursion were increased 30% ( P < 0.01) in both age groups. Muscle cross-sectional area was reduced by 12% ( P < 0.01) in response to the increased mechanical advantage, and this reduction was unaffected by age. Fiber length change was also unaffected by age, with both groups showing a trend ( P < 0.10) for slightly (6%) increased fiber length. Retinaculum transection results in shorter muscle length in all joint configurations, so this trend opposes the fiber length decrease predicted by an adaptation to muscle length and indicates that fiber length is influenced by dynamic mechanical signals in addition to static length.

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Fine structure of early degenerating myofibers in the tibialis anterior of young ‘MDX’ mouse

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010367x ◽

1988 ◽

Vol 46 ◽

pp. 322-323

Author(s):

H.D. Geissinger ◽

C.K. McDonald-Taylor

Keyword(s):

Fine Structure ◽

Muscle Regeneration ◽

Tibialis Anterior ◽

Genetic Defect ◽

Mdx Mouse ◽

Mdx Mice ◽

Histopathological Changes ◽

Electron Microscopic ◽

Dystrophic Mouse ◽

Preliminary Study

A new strain of mice, which had arisen by mutation from a dystrophic mouse colony was designated ‘mdx’, because the genetic defect, which manifests itself in brief periods of muscle destruction followed by episodes of muscle regeneration appears to be X-linked. Further studies of histopathological changes in muscle from ‘mdx’ mice at the light microscopic or electron microscopic levels have been published, but only one preliminary study has been on the tibialis anterior (TA) of ‘mdx’ mice less than four weeks old. Lesions in the ‘mdx’ mice vary between different muscles, and centronucleation of fibers in all muscles studied so far appears to be especially prominent in older mice. Lesions in young ‘mdx’ mice have not been studied extensively, and the results appear to be at variance with one another. The degenerative and regenerative aspects of the lesions in the TA of 23 to 26-day-old ‘mdx’ mice appear to vary quantitatively.

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Regenerating myofibers in tibialis anterior muscles of young ‘MDX’ mice

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100127943 ◽

1987 ◽

Vol 45 ◽

pp. 726-727

Author(s):

H. D. Geissinge ◽

L.D. Rhodes

Keyword(s):

Muscular Dystrophy ◽

Mouse Model ◽

Tibialis Anterior ◽

Physiological Activity ◽

Mdx Mice ◽

Mode Of Inheritance

A recently discovered mouse model (‘mdx’) for muscular dystrophy in man may be of considerable interest, since the disease in ‘mdx’ mice is inherited by the same mode of inheritance (X-linked) as the human Duchenne (DMD) muscular dystrophy. Unlike DMD, which results in a situation in which the continual muscle destruction cannot keep up with abortive regenerative attempts of the musculature, and the sufferers of the disease die early, the disease in ‘mdx’ mice appears to be transient, and the mice do not die as a result of it. In fact, it has been reported that the severely damaged Tibialis anterior (TA) muscles of ‘mdx’ mice seem to display exceptionally good regenerative powers at 4-6 weeks, so much so, that these muscles are able to regenerate spontaneously up to their previous levels of physiological activity.

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