Dear Andrea

It's an interesting issue.

Differences in CSA were not mirrored by differences in tendon stiffness in every group. Taken together, these results suggest that theories formulated to explain tendon design may apply in the context of adaptation to altered mechanical loading: Structural integrity may be maintained via hypertrophy but tendon stiffness and CSA can be uncoupled, presumably to fulfill functional requirements.

Read more in:

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0158441#sec014

Also, you can check these articles:

https://www.ncbi.nlm.nih.gov/pubmed/19145654

http://iopscience.iop.org/article/10.1088/0967-3334/32/6/005/pdf

https://www.ncbi.nlm.nih.gov/pubmed/28280975

https://dspace.lboro.ac.uk/dspace-jspui/handle/2134/24712

According to my understanding stiffness of tendons is indirectly related with the properties of the muscle . This can be seen from patients with weakened muscles and quite stiff tendons. Stiffness of the muscle in general is variable and depends on innervation.

Feldman, A.G., Journal of Motor Behavior, 18:17–54, 1986.

Feldman, A.G., Wiley Interdisciplinary Reviews: Cognitive Science, 2:287–304, 2011

You can look

https://arxiv.org/ftp/arxiv/papers/1307/1307.2809.pdf

You can discuss only the dependence of maximal muscle stiffness on the CSA, for example. Previous colleagues offer similar estimates, but they are not perfect. True descriptions of a neat test for such a dependency I don't know.

Interesting question Andrea!

I will reply with another question: which muscle-tendon unit are we taking in consideration? This, already, can sparkle some different thoughts on the topic.

Nonetheless, tendon stiffness is mostly related to a structural arrangement or remodelling (in response to loading and mechanical stimuli) of tendon material/components. Thus, is it stiffness more related to tension? And if so, does more mass mean more tension?

I attach a recent paper from one of our ex PhD students. It's just a cross sectional observation in elderly vs. young, but maybe interesting.

Article Muscle and Tendon Contributions To Reduced Rate of Torque De...

Ciao!

Marty

We have been measuring human muscle forces during orthopaedic surgery, directly at their tendon and as a function of joint angle after stimulating them. Hence, we obtain muscle force-joint able characteristics, from which muscle stiffness can be determined in active state. We also measure relevant anthropometrics before surgery, including circumference of the limb and tendon cross-sectional area if relevant. One finding which is very striking is that human muscle forces vary a lot from participant to participant despite their similar conditions. One aim we have is to see if such pre-surgery anthropometrics are good metrics to characterise the target muscle. However, there is almost never a correlation between e.g., the peak force and those metrics. In one particular study (which is attached), we looked to see if tendon stress instead of tendon force can remove the variability. In order to achieve that, we calculated tendon cross-sectional areas of the participants and determined the stress as force/cross-sectional area. This did limit some of the variability but did not eliminate it. We have been measuring forces of spastic hamstring muscles of cerebral palsy patients to characterise the pathological knee condition. However, such anthropometrics and the actual muscle force do not seem to correlate. I will attach one recent example of such intraoperative CP work as well.

Sorry for the late answer.

Thank you very much all for your help.

Best regards

Andrea

1. файл subtopics.txt - 20 topics from scientific articles on CSA "pennation angle" muscle tendon stiffness

2. файл a3_potential_novelty.xlsm - articles published in 3 last years the best on being potentially with novelty

3. файл a1_basic_articles.xlsm - most important articles with basic knowledge on topic

=

Here are 20 topics from the articles which contain words “CSA "pennation angle" muscle tendon stiffness” in their titles or abstracts. Each topic is presented with 20 words and 20 phrases as it is done in these articles.

As from previous experience not more then 30% of these topics will be useful for you.

Reading these topics will require efforts from you, since this is not a coherent presentation, and each topic is a list of substances, methods, theories, cases, etc. associated with this topic. Try to be patient, in the hope that new hypotheses and thoughts will appear.

Feel free to make Feedback