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Response of tibialis anterior tendon to a chronic exposure of stretch-shortening cycles: age effects.

Ensey JS, Hollander MS, Wu JZ, Kashon ML, Baker BB, Cutlip RG - Biomed Eng Online (2009)

Bottom Line: Old exposed and control tendons exhibited significantly higher loads at the inflection point than their young counterparts (p < 0.05 for both comparisons).The chronic protocol enhanced the elastic stiffness of young tendon and the loads in both the young and old tendons.The old exposed tendons were found to exhibit higher load capacity than their younger counterparts, which differed from our initial hypothesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Institute for Occupational Safety and Health (NIOSH), Health Effects Laboratory Division, Morgantown, West Virginia 26505, USA. jensey@cdc.gov

ABSTRACT

Background: The purpose of the current study was to investigate the effects of aging on tendon response to repetitive exposures of stretch-shortening cycles (SSC's).

Methods: The left hind limb from young (3 mo, N = 4) and old (30 mo, N = 9) male Fisher 344 x Brown Norway rats were exposed to 80 maximal SSCs (60 deg/s, 50 deg range of motion) 3 x/week for 4.5 weeks in vivo. After the last exposure, tendons from the tibialis anterior muscle were isolated, stored at -80 degrees C, and then tested using a micro-mechanical testing machine. Deformation of each tendon was evaluated using both relative grip-to-grip displacements and reference marks via a video system.

Results: At failure, the young control tendons had higher strain magnitude than the young exposed (p < 0.01) and the old control tendons (p < .0001). Total load at inflection was affected by age only (p < 0.01). Old exposed and control tendons exhibited significantly higher loads at the inflection point than their young counterparts (p < 0.05 for both comparisons). At failure, the old exposed tendons carried higher loads than the young exposed tendons (p < 0.05). Stiffness was affected by age only at failure where the old tendons exhibited higher stiffness in both exposed and control tendons than their young counterparts (p < 0.05 and p < 0.01, respectively).

Conclusion: The chronic protocol enhanced the elastic stiffness of young tendon and the loads in both the young and old tendons. The old exposed tendons were found to exhibit higher load capacity than their younger counterparts, which differed from our initial hypothesis.

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(A) The stiffness from unloaded and loaded limbs at the inflection point by age group. (B) The stiffness from unloaded and loaded limbs at the failure point by age group. (C) Normalized stiffness for old and young tendons at the inflection point. Each loaded tendon is normalized to its unloaded control. (D) Normalized stiffness for old and young tendons at the failure point. Each loaded tendon is normalized to its unloaded control. Data is depicted as mean values ± standard error. Different letters denote significance at the 0.05 level.
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Figure 5: (A) The stiffness from unloaded and loaded limbs at the inflection point by age group. (B) The stiffness from unloaded and loaded limbs at the failure point by age group. (C) Normalized stiffness for old and young tendons at the inflection point. Each loaded tendon is normalized to its unloaded control. (D) Normalized stiffness for old and young tendons at the failure point. Each loaded tendon is normalized to its unloaded control. Data is depicted as mean values ± standard error. Different letters denote significance at the 0.05 level.

Mentions: There was no significant difference between two age groups or limbs for stiffness at the inflection point (Fig 5A). The normalized stiffness (stiffness of exposed limb tendon/stiffness of control limb tendon) at the inflection point was 2.38 ± 1.26 and 2.44 ± 0.86 for old and young tendons, respectively (Fig 5B).


Response of tibialis anterior tendon to a chronic exposure of stretch-shortening cycles: age effects.

Ensey JS, Hollander MS, Wu JZ, Kashon ML, Baker BB, Cutlip RG - Biomed Eng Online (2009)

(A) The stiffness from unloaded and loaded limbs at the inflection point by age group. (B) The stiffness from unloaded and loaded limbs at the failure point by age group. (C) Normalized stiffness for old and young tendons at the inflection point. Each loaded tendon is normalized to its unloaded control. (D) Normalized stiffness for old and young tendons at the failure point. Each loaded tendon is normalized to its unloaded control. Data is depicted as mean values ± standard error. Different letters denote significance at the 0.05 level.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2710328&req=5

Figure 5: (A) The stiffness from unloaded and loaded limbs at the inflection point by age group. (B) The stiffness from unloaded and loaded limbs at the failure point by age group. (C) Normalized stiffness for old and young tendons at the inflection point. Each loaded tendon is normalized to its unloaded control. (D) Normalized stiffness for old and young tendons at the failure point. Each loaded tendon is normalized to its unloaded control. Data is depicted as mean values ± standard error. Different letters denote significance at the 0.05 level.
Mentions: There was no significant difference between two age groups or limbs for stiffness at the inflection point (Fig 5A). The normalized stiffness (stiffness of exposed limb tendon/stiffness of control limb tendon) at the inflection point was 2.38 ± 1.26 and 2.44 ± 0.86 for old and young tendons, respectively (Fig 5B).

Bottom Line: Old exposed and control tendons exhibited significantly higher loads at the inflection point than their young counterparts (p < 0.05 for both comparisons).The chronic protocol enhanced the elastic stiffness of young tendon and the loads in both the young and old tendons.The old exposed tendons were found to exhibit higher load capacity than their younger counterparts, which differed from our initial hypothesis.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Institute for Occupational Safety and Health (NIOSH), Health Effects Laboratory Division, Morgantown, West Virginia 26505, USA. jensey@cdc.gov

ABSTRACT

Background: The purpose of the current study was to investigate the effects of aging on tendon response to repetitive exposures of stretch-shortening cycles (SSC's).

Methods: The left hind limb from young (3 mo, N = 4) and old (30 mo, N = 9) male Fisher 344 x Brown Norway rats were exposed to 80 maximal SSCs (60 deg/s, 50 deg range of motion) 3 x/week for 4.5 weeks in vivo. After the last exposure, tendons from the tibialis anterior muscle were isolated, stored at -80 degrees C, and then tested using a micro-mechanical testing machine. Deformation of each tendon was evaluated using both relative grip-to-grip displacements and reference marks via a video system.

Results: At failure, the young control tendons had higher strain magnitude than the young exposed (p < 0.01) and the old control tendons (p < .0001). Total load at inflection was affected by age only (p < 0.01). Old exposed and control tendons exhibited significantly higher loads at the inflection point than their young counterparts (p < 0.05 for both comparisons). At failure, the old exposed tendons carried higher loads than the young exposed tendons (p < 0.05). Stiffness was affected by age only at failure where the old tendons exhibited higher stiffness in both exposed and control tendons than their young counterparts (p < 0.05 and p < 0.01, respectively).

Conclusion: The chronic protocol enhanced the elastic stiffness of young tendon and the loads in both the young and old tendons. The old exposed tendons were found to exhibit higher load capacity than their younger counterparts, which differed from our initial hypothesis.

Show MeSH
Related in: MedlinePlus