<i>Passive and Active Tension-Length Diagrams of Intact Skeletal Muscle in Normal Women of Different Ages</i>

Botelho, Stella Y.; Cander, Leon; Guiti, N.

doi:10.1152/jappl.1954.7.1.93

Cited by 9 publications

(7 citation statements)

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“…Physiological length changes in muscle in a previous study were 20% or less [42]. Researchers in other studies who have shown positive results by removing extracellular calcium or blocking stretch-activated receptors used length changes of 30% to 40% of L o [12,14,15].…”

Section: Discussionmentioning

confidence: 99%

Transgenic overexpression of γ-cytoplasmic actin protects against eccentric contraction-induced force loss in mdx mice

et al. 2011

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Backgroundγ-cytoplasmic (γ-cyto) actin levels are elevated in dystrophin-deficient mdx mouse skeletal muscle. The purpose of this study was to determine whether further elevation of γ-cyto actin levels improve or exacerbate the dystrophic phenotype of mdx mice.MethodsWe transgenically overexpressed γ-cyto actin, specifically in skeletal muscle of mdx mice (mdx-TG), and compared skeletal muscle pathology and force-generating capacity between mdx and mdx-TG mice at different ages. We investigated the mechanism by which γ-cyto actin provides protection from force loss by studying the role of calcium channels and stretch-activated channels in isolated skeletal muscles and muscle fibers. Analysis of variance or independent t-tests were used to detect statistical differences between groups.ResultsLevels of γ-cyto actin in mdx-TG skeletal muscle were elevated 200-fold compared to mdx skeletal muscle and incorporated into thin filaments. Overexpression of γ-cyto actin had little effect on most parameters of mdx muscle pathology. However, γ-cyto actin provided statistically significant protection against force loss during eccentric contractions. Store-operated calcium entry across the sarcolemma did not differ between mdx fibers compared to wild-type fibers. Additionally, the omission of extracellular calcium or the addition of streptomycin to block stretch-activated channels did not improve the force-generating capacity of isolated extensor digitorum longus muscles from mdx mice during eccentric contractions.ConclusionsThe data presented in this study indicate that upregulation of γ-cyto actin in dystrophic skeletal muscle can attenuate force loss during eccentric contractions and that the mechanism is independent of activation of stretch-activated channels and the accumulation of extracellular calcium.

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Section: Discussionmentioning

confidence: 99%

Transgenic overexpression of γ-cytoplasmic actin protects against eccentric contraction-induced force loss in mdx mice

et al. 2011

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“…A prolongation of relaxation in elderly [10,11] increases tetanus fusion which in result gives a bigger muscle stiffness. As mentioned previously, MMG signals are related to muscle stiffness [14] and force fluctuation; both factors, however, change with age [7,8,18,42,43]. In addition, the effect of aging on the angle-EMG or angle-MMG relation might not be the same in the triceps brachii, biceps brachii, and brachioradialis muscles because they differ in morphology [9,31,39] and functional capabilities [39].…”

Section: Introductionmentioning

confidence: 95%

EMG and MMG of agonist and antagonist muscles as a function of age and joint angle

Jaskólska

Kisiel-Sajewicz

Brzenczek-Owczarzak³

et al. 2006

Journal of Electromyography and Kinesiology

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“…Increased collagen content and stiffness are seen in numerous musculoskeletal pathologies, including spasticity (M. Brown et al, 1999; Damiano et al, 2001; Gracies, 2005; Vaz et al, 2006), as well as typical aging (Alnaqeeb et al, 1984; Botelho et al, 1954; Larsson et al, 1979; Tomonaga, 1977). It is clear that muscle stiffness is closely related to joint constraint – increased muscle stiffness is associated with poor range of motion, while reductions in muscle stiffness may predispose to joint subluxation (Johns and Wright, 1962; Vandervoort, 1999).…”

Section: Introductionmentioning

confidence: 99%

Validation of shear wave elastography in skeletal muscle

Eby

Song

Chen

et al. 2013

Journal of Biomechanics

438

385

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Skeletal muscle is a very dynamic tissue, thus accurate quantification of skeletal muscle stiffness throughout its functional range is crucial to improve the physical functioning and independence following pathology. Shear wave elastography (SWE) is an ultrasound-based technique that characterizes tissue mechanical properties based on the propagation of remotely induced shear waves. The objective of this study is to validate SWE throughout the functional range of motion of skeletal muscle for three ultrasound transducer orientations. We hypothesized that combining traditional materials testing (MTS) techniques with SWE measurements will show increased stiffness measures with increasing tensile load, and will correlate well with each other for trials in which the transducer is parallel to underlying muscle fibers. To evaluate this hypothesis, we monitored the deformation throughout tensile loading of four porcine brachialis whole-muscle tissue specimens, while simultaneously making SWE measurements of the same specimen. We used regression to examine the correlation between Young's modulus from MTS and shear modulus from SWE for each of the transducer orientations. We applied a generalized linear model to account for repeated testing. Model parameters were estimated via generalized estimating equations. The regression coefficient was 0.1944, with a 95% confidence interval of (0.1463 – 0.2425) for parallel transducer trials. Shear waves did not propagate well for both the 45° and perpendicular transducer orientations. Both parallel SWE and MTS showed increased stiffness with increasing tensile load. This study provides the necessary first step for additional studies that can evaluate the distribution of stiffness throughout muscle.

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Passive and Active Tension-Length Diagrams of Intact Skeletal Muscle in Normal Women of Different Ages

Cited by 9 publications

References 0 publications

Transgenic overexpression of γ-cytoplasmic actin protects against eccentric contraction-induced force loss in mdx mice

Transgenic overexpression of γ-cytoplasmic actin protects against eccentric contraction-induced force loss in mdx mice

EMG and MMG of agonist and antagonist muscles as a function of age and joint angle

Validation of shear wave elastography in skeletal muscle

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