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Method to Measure Tone of Axial and Proximal Muscle
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Age-related differences in trunk intrinsic stiffness.

Milad Vazirian1, Iman Shojaei1, Rebecca L Tromp1

  • 1Department of Biomedical Engineering, University of Kentucky, 514E Robotic and Manufacturing Building, Lexington, KY 40506, USA.

Journal of Biomechanics
|October 14, 2015
PubMed
Summary

Aging did not significantly affect trunk intrinsic stiffness, a key factor in spinal stability. Male participants and higher effort levels showed increased stiffness, suggesting volitional muscle activity is crucial for stability, not age-related decline.

Keywords:
AgingPerturbation testSpinal stabilityTrunk apparent massTrunk intrinsic stiffness

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Area of Science:

  • Biomechanics
  • Gerontology
  • Musculoskeletal Health

Background:

  • Spinal instability is linked to low back pain (LBP), which increases with age.
  • The aging workforce necessitates understanding age-related changes in spinal stability.
  • Trunk intrinsic stiffness is a critical component of spinal stability.

Purpose of the Study:

  • To investigate age-related differences in trunk intrinsic stiffness.
  • To assess the influence of gender, effort level, and neuromuscular patterns on trunk stiffness.
  • To determine if aging impacts the lower back's contribution to spinal stability.

Main Methods:

  • Sixty participants (aged 20-70) were divided into five age groups.
  • Displacement-controlled perturbation tests were performed in an upright standing posture.
  • Participants held four different levels of trunk extension efforts; trunk intrinsic stiffness was measured.

Main Results:

  • No significant age-related differences in trunk intrinsic stiffness were observed.
  • Trunk stiffness was significantly higher in males compared to females.
  • Stiffness increased significantly with higher levels of trunk extension effort.
  • Lower back neuromuscular patterns did not significantly influence trunk intrinsic stiffness.

Conclusions:

  • Aging does not appear to diminish the volitional contribution of the lower back musculature to spinal stability.
  • Male gender and increased voluntary effort enhance trunk intrinsic stiffness.
  • The findings suggest that age-related changes in strength do not necessarily reduce spinal stability contributions from the lower back muscles.