AI Article Synopsis
- The study examined how aging affects the passive properties of single muscle fibers in males, comparing young (average age 25.4) and older (average age 68.9) participants.
- Older individuals displayed significantly higher passive elastic moduli and passive stress in their muscle fibers at specific sarcomere lengths, indicating stiffness increases with age.
- These findings offer new understanding of how muscle fiber properties change as people age, particularly focusing on length-dependency.
Article Abstract
Purpose: Studies have revealed an age-related decrease in the ability to produce force as well as an increase in the contractile stiffness and passive stress of single muscle fibres. However, further insight into age-related changes to the passive properties of human skeletal muscles is needed. The aim of this study was to characterize single muscle fibre passive properties from young and old males across a physiologic range of sarcomere lengths (SLs).
Methods: Ten young ([YM]: mean age: 25.4 years) and ten old ([OM]: mean age: 68.9 years) males participated. Vastus lateralis muscles were biopsied and 182 fibres were tested and analyzed (90 YM and 92 OM) using a cumulative stretch-relaxation protocol. Passive mechanical characteristics of each fibre were obtained by fitting the integral of the logistic function to experimental stress-SL data.
Results: Muscle fibres from older individuals had significantly greater passive elastic moduli at short SL (1.9-2.65 μm) compared with young (p < 0.05). This resulted in a significantly larger passive stress for SLs between 2.1 μm and 3.55 μm for older individuals when compared with young (p < 0.05).
Conclusion: These results provide novel insight into the length dependency of changes in single muscle fibre passive mechanical properties with age.
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| http://dx.doi.org/10.1016/j.exger.2020.110968 | DOI Listing |
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