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Copyright of Journal of Japan Society of Library & Information Science is the property of Nippon Toshokan Joho Gakkai and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Japan Society of Library & Information Science is the property of Nippon Toshokan Joho Gakkai and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In baseball pitching, pitcher's trunk is known to have kinematic and kinetic functions for conveying the motion energy from the lower limb to the upper limb. In such context, a term, "the stretching of the chest", is often used in coaching. Although several qualitative reports on the term have been published, its biomechanical features and functions are still unclear, due to the lack of quantitative studies. In order to eliminate such ambiguity, we have been developing a quantitative analysis of the stretching of the chest. First, Fukushima (2014) proposed parameter S defined from the positions of several reflective markers secured to the skin surface of the thoracic vertebrae. The parameter enabled us to evaluate the curvature of the vertebrae that depends primarily on the stretching of the chest in pitching. In this paper, we applied this parameter to the analysis of baseball pitching in order to clarify a role of the stretching of the chest in the kinetic chain. Experiments using 12 subjects verified that the stretching of the chest could take part in conveying the motion energy through a time-series analysis, suggesting that the stretching and stooping, motion of the chest could be one of the factors of the kinetic chain. [ABSTRACT FROM AUTHOR]

During a typical baseball pitch, the player's trunk performs several functions that convey motion energy from the lower- to the upper-limb. In this context, the phrase "stretching the chest" is used, most often by the coach. But, its biomechanical essence is still unclear, being used in the qualitative sense. To clarify this term in coaching contexts, we proposed a novel evaluation parameter denoted by S, using the curvature of the thoracic spine, which is measurable by an ordinary marker-based motion capture system. In the first step of its validation, we analyzed MR images of the thoracic spine, while placing the chest under normal stress, in order to verify the relationship between the stretching-process and the curvature of the thoracic spine. We then conducted motion capture-based analysis of the relationship between parameter S and basic motions of the upper arm and trunk. Consequently, parameter S was determined to be independent of other motion parameters, except horizontal adduction and abduction of the upper arm. Finally, we applied parameter S to the analysis of actual baseball pitches, and came to understand its natural flexibility over time, and independence from horizontal adduction and abduction of the upper arm and retroflexion of the trunk. [ABSTRACT FROM AUTHOR]