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Normal aging alters in vivo passive biomechanical response of the rat gastrocnemius-Achilles muscle-tendon unit.

Publication ,  Journal Article
Plate, JF; Wiggins, WF; Haubruck, P; Scott, AT; Smith, TL; Saul, KR; Mannava, S
Published in: J Biomech
February 1, 2013

Predisposition to Achilles tendon (AT) ruptures in middle-aged individuals may be associated with age-related changes to inherent passive biomechanical properties of the gastrocnemius-Achilles (GC-AT) muscle-tendon unit, due to known muscle-tendon structural changes in normal aging. The goal of this study was to determine whether the passive biomechanical response of the GC-AT muscle-tendon unit was altered with age in 6 young (8 months) and 6 middle-aged (24 months) F344xBN hybrid rats from the National Institute on Aging colony. Fung's quasilinear viscoelastic (QLV) model was used to determine in vivo history and time-dependent load-relaxation response of the GC-AT. Effective stiffness and modulus were also estimated using linear regression analysis. Fung's QLV revealed a significantly decreased magnitude of the relaxation response (parameter C, p=0.026) in middle-aged animals compared to young animals (0.108±0.007 vs. 0.144±0.015), with similar time-dependent viscous GC-AT properties (τ(1), τ(2)). The product of elastic parameters (A*B), which represents the initial slope of the elastic response, was significantly increased by 50% in middle-aged rats (p=0.014). Estimated GC-AT stiffness increased 28% at peak tensions in middle-aged rats (2.7±0.2 N/mm) compared to young rats (1.9±0.2 N/mm; p=0.036). While the limitations of this animal model must be considered, the changes we describe could be associated with the observation that GC-AT pathology and injury is more common in middle-aged individuals. Further studies are necessary to characterize the load-to-failure behavior of AT in middle-aged compared to young animals.

Duke Scholars

Published In

J Biomech

DOI

EISSN

1873-2380

Publication Date

February 1, 2013

Volume

46

Issue

3

Start / End Page

450 / 455

Location

United States

Related Subject Headings

  • Weight-Bearing
  • Rats
  • Muscle, Skeletal
  • Models, Biological
  • Middle Aged
  • Male
  • Humans
  • Elasticity
  • Biomedical Engineering
  • Animals
 

Citation

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Plate, J. F., Wiggins, W. F., Haubruck, P., Scott, A. T., Smith, T. L., Saul, K. R., & Mannava, S. (2013). Normal aging alters in vivo passive biomechanical response of the rat gastrocnemius-Achilles muscle-tendon unit. J Biomech, 46(3), 450–455. https://doi.org/10.1016/j.jbiomech.2012.11.007
Journal cover image

Published In

J Biomech

DOI

EISSN

1873-2380

Publication Date

February 1, 2013

Volume

46

Issue

3

Start / End Page

450 / 455

Location

United States

Related Subject Headings

  • Weight-Bearing
  • Rats
  • Muscle, Skeletal
  • Models, Biological
  • Middle Aged
  • Male
  • Humans
  • Elasticity
  • Biomedical Engineering
  • Animals