Looking for the inertial mass properties of the finger segments.

[Hiroshi Tanaka]

I have X-Y-Z coordinate data during baseball pitching via a surface marker-based motion capture system. I would like to use the inertial mass properties of the finger segments when doing segmentation and joint reaction force estimation in the inverse dynamic calculation. Can anyone please let me know the inertial mass properties of the finger segments for young and/or adult athletes? Thank you for your help.

[Edmund Cramp]

This is not the answer but you might find this article interesting - A Fabricated Force Glove That Measures Hand Forces during Activities of Daily Living

[Ton van den Bogert]

To get good inverse dynamic results for elbow and shoulder, I am almost certain that you only need inertial properties for the hand (including fingers), which can be found in the literature. This is because the finger masses are small, relative to the other masses, and the finger accelerations are very similar to the hand accelerations.

You can still use a kinematic analysis that includes finger joints, as long as finger masses are set to zero, and finger masses included in the hand segment.

If you need to justify such model simplifications, you can use sensitivity analysis. For instance, make a rough estimate for finger inertial properties, based on cylinder geometry and density of water. Your inverse dynamic results will probably not change at all, compared to using zeroes. And therefore, you also don't need to worry about getting different values for young and adult athletes. Sensitivity analysis is a good way to find out which parameters are important enough to spend more time on.

Ton van den Bogert

[Hiroshi Tanaka]

I appreciate all of you sharing your professional knowledge. And thanks to let me know the interesting info on this issue.

As taking your point, our results may not show many changes despite the use of finger properties. Anyway, I am going to check the effect of finger properties from the sensitivity analysis on the kinetic parameters of the pitching arm. Again, thank you so much. If you find out other useful info on this issue, please let me know.

[Glenn Fleisig]

Edmund and Hiroshi, there is also this article on finger forces during baseball pitching: https://pubmed.ncbi.nlm.nih.gov/28500954/.

Ton and Hiroshi, it seems worthwhile to conduct sensitivity analysis. However, it is still unfortunate that there are no finger inertial properties data available.

[Hiroshi Tanaka]

Glenn, thank you for giving us your professional advice about this issue. I am impressed with your creative work that has identified the force production patterns of the 4 fingers during baseball pitching via a novel apparatus. As you well know, ideally, I would like to estimate finger force using the measured 3-D position data of skin-surface markers, and finger properties.