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Stretch speed-dependent myofiber damage and functional deficits in rat skeletal muscle induced by lengthening contraction.

Mori T, Agata N, Itoh Y, Miyazu-Inoue M, Sokabe M, Taguchi T, Kawakami K - Physiol Rep (2014)

Bottom Line: Isometric torque of dorsiflexion measured 2 days after LC decreased progressively with LC angular velocity (by 68% reduction at 400 deg/sec).The angular velocity of muscle stretch during LC is thus a critical determinant of the degree of damage, and LC appears to damage type IIb fibers preferentially, resulting in a disproportionate reduction in isometric torque.This LC response is an important consideration for the design of physical conditioning and rehabilitation regimens.

View Article: PubMed Central - PubMed

Affiliation: Physical and Occupational Therapy Program, Nagoya University Graduate School of Medicine, Nagoya, Japan Department of Rehabilitation, Nagoya University Hospital, Nagoya, Japan.

No MeSH data available.


Related in: MedlinePlus

Stretch speed‐dependent muscle damage. (A) Number of damaged muscle fibers labeled with Evans blue dye (EBD) in transverse sections of tibialis anterior (TA) 2 days after lengthening contraction (LC). The number of EBD‐positive fibers in the entire cross‐sectional area (CSA) of TA increases with angular velocity of muscle stretch (n = 7, 8, 19 and 7 at angular velocities of 50, 100, 200, and 400 deg/sec, respectively). (B) The proportion of CSA occupied by EBD‐positive fibers increases with LC angular velocity (n = 7, 8, 19, and 7 at angular velocities of 50, 100, 200, and 400 deg/sec, respectively). Data are shown as mean ± SEM. Values with different symbols above bars are significantly different.
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fig03: Stretch speed‐dependent muscle damage. (A) Number of damaged muscle fibers labeled with Evans blue dye (EBD) in transverse sections of tibialis anterior (TA) 2 days after lengthening contraction (LC). The number of EBD‐positive fibers in the entire cross‐sectional area (CSA) of TA increases with angular velocity of muscle stretch (n = 7, 8, 19 and 7 at angular velocities of 50, 100, 200, and 400 deg/sec, respectively). (B) The proportion of CSA occupied by EBD‐positive fibers increases with LC angular velocity (n = 7, 8, 19, and 7 at angular velocities of 50, 100, 200, and 400 deg/sec, respectively). Data are shown as mean ± SEM. Values with different symbols above bars are significantly different.

Mentions: The number of EBD‐positive cells within the entire CSA of the TA belly increased progressively with angular velocity (50 deg/sec: 31.9 ± 14.0 cells, n = 7; 100 deg/sec: 598.8 ± 241.4 cells, n = 8; 200 deg/sec: 1677.2 ± 133.2 cells, n = 19; 400 deg/sec: 2252.6 ± 285.8 cells, n = 7; Fig. 3A). The number of labeled cells was significantly higher in TA sections from animals subjected to LC at 200 deg/sec or 400 deg/sec compared with 100 deg/sec or 50 deg/sec (P < 0.05, one‐way ANOVA followed by Tukey's post hoc test). The mean total number of myofibers in the entire CSA of the TA counted in 1 rat following LC at an angular velocity of 200 deg/sec was 11487. The proportion of the total CSA of the TA belly occupied by EBD‐positive fibers also increased progressively with angular velocity (50 deg/sec: 1.8% ± 0.1%, n = 7; 100 deg/sec: 10.4% ± 1.3%, n = 8; 200 deg/sec: 25.0% ± 0.4%, n = 19; 400 deg/sec: 37.0% ± 1.6%, n = 7; Fig. 3B) and was significantly higher in sections from animals subjected to LC at 200 deg/sec or 400 deg/sec compared with 100 deg/sec or 50 deg/sec (P < 0.05, one‐way ANOVA followed by Tukey's post hoc test).


Stretch speed-dependent myofiber damage and functional deficits in rat skeletal muscle induced by lengthening contraction.

Mori T, Agata N, Itoh Y, Miyazu-Inoue M, Sokabe M, Taguchi T, Kawakami K - Physiol Rep (2014)

Stretch speed‐dependent muscle damage. (A) Number of damaged muscle fibers labeled with Evans blue dye (EBD) in transverse sections of tibialis anterior (TA) 2 days after lengthening contraction (LC). The number of EBD‐positive fibers in the entire cross‐sectional area (CSA) of TA increases with angular velocity of muscle stretch (n = 7, 8, 19 and 7 at angular velocities of 50, 100, 200, and 400 deg/sec, respectively). (B) The proportion of CSA occupied by EBD‐positive fibers increases with LC angular velocity (n = 7, 8, 19, and 7 at angular velocities of 50, 100, 200, and 400 deg/sec, respectively). Data are shown as mean ± SEM. Values with different symbols above bars are significantly different.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4255819&req=5

fig03: Stretch speed‐dependent muscle damage. (A) Number of damaged muscle fibers labeled with Evans blue dye (EBD) in transverse sections of tibialis anterior (TA) 2 days after lengthening contraction (LC). The number of EBD‐positive fibers in the entire cross‐sectional area (CSA) of TA increases with angular velocity of muscle stretch (n = 7, 8, 19 and 7 at angular velocities of 50, 100, 200, and 400 deg/sec, respectively). (B) The proportion of CSA occupied by EBD‐positive fibers increases with LC angular velocity (n = 7, 8, 19, and 7 at angular velocities of 50, 100, 200, and 400 deg/sec, respectively). Data are shown as mean ± SEM. Values with different symbols above bars are significantly different.
Mentions: The number of EBD‐positive cells within the entire CSA of the TA belly increased progressively with angular velocity (50 deg/sec: 31.9 ± 14.0 cells, n = 7; 100 deg/sec: 598.8 ± 241.4 cells, n = 8; 200 deg/sec: 1677.2 ± 133.2 cells, n = 19; 400 deg/sec: 2252.6 ± 285.8 cells, n = 7; Fig. 3A). The number of labeled cells was significantly higher in TA sections from animals subjected to LC at 200 deg/sec or 400 deg/sec compared with 100 deg/sec or 50 deg/sec (P < 0.05, one‐way ANOVA followed by Tukey's post hoc test). The mean total number of myofibers in the entire CSA of the TA counted in 1 rat following LC at an angular velocity of 200 deg/sec was 11487. The proportion of the total CSA of the TA belly occupied by EBD‐positive fibers also increased progressively with angular velocity (50 deg/sec: 1.8% ± 0.1%, n = 7; 100 deg/sec: 10.4% ± 1.3%, n = 8; 200 deg/sec: 25.0% ± 0.4%, n = 19; 400 deg/sec: 37.0% ± 1.6%, n = 7; Fig. 3B) and was significantly higher in sections from animals subjected to LC at 200 deg/sec or 400 deg/sec compared with 100 deg/sec or 50 deg/sec (P < 0.05, one‐way ANOVA followed by Tukey's post hoc test).

Bottom Line: Isometric torque of dorsiflexion measured 2 days after LC decreased progressively with LC angular velocity (by 68% reduction at 400 deg/sec).The angular velocity of muscle stretch during LC is thus a critical determinant of the degree of damage, and LC appears to damage type IIb fibers preferentially, resulting in a disproportionate reduction in isometric torque.This LC response is an important consideration for the design of physical conditioning and rehabilitation regimens.

View Article: PubMed Central - PubMed

Affiliation: Physical and Occupational Therapy Program, Nagoya University Graduate School of Medicine, Nagoya, Japan Department of Rehabilitation, Nagoya University Hospital, Nagoya, Japan.

No MeSH data available.


Related in: MedlinePlus