{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:36:30Z","timestamp":1760060190721,"version":"build-2065373602"},"reference-count":15,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2025,8,15]],"date-time":"2025-08-15T00:00:00Z","timestamp":1755216000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"PROCIENCIA","award":["PE501080681-2022-PROCIENCIA"],"award-info":[{"award-number":["PE501080681-2022-PROCIENCIA"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JFMK"],"abstract":"<jats:p>Background: Skilled human movement, such as the golf swing, emerges from coordinated rotational and translational dynamics. This study investigates pitch\u2014a screw-theoretic invariant defined as the ratio of linear to angular velocity along the instantaneous screw axis (ISA)\u2014as a compact metric for quantifying motor coordination. Methods: We reanalyzed a validated motion capture dataset involving a proficient and a novice female golfer. ISA trajectories and pitch values were computed from 3D marker data, and synchronized with vertical ground reaction force (GRF) signals collected via force plate. Results: The proficient golfer exhibited tightly bounded pitch oscillations (approximately \u00b10.0025 cm\/rad) that were temporally aligned with a single, well-defined GRF peak. In contrast, the novice showed irregular pitch fluctuations (\u22120.025 to +0.01 cm\/rad) and asynchronous GRF patterns with multiple peaks. Conclusions: These findings demonstrate that pitch can serve as a biomechanical indicator of skilled performance, reflecting the degree of intersegmental coordination and force timing. Screw theory thus offers a rigorous framework for evaluating movement efficiency in sport and rehabilitation contexts.<\/jats:p>","DOI":"10.3390\/jfmk10030315","type":"journal-article","created":{"date-parts":[[2025,8,15]],"date-time":"2025-08-15T08:39:07Z","timestamp":1755247147000},"page":"315","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Pitch Invariance Reveals Skill-Specific Coordination in Human Movement: A Screw-Theoretic Reanalysis of Golf Swing Dynamics"],"prefix":"10.3390","volume":"10","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0527-5129","authenticated-orcid":false,"given":"Wangdo","family":"Kim","sequence":"first","affiliation":[{"name":"Ingenieria Mecanica, Universidad de Ingenieria y Tecnologia\u2014UTEC, Lima 15063, Peru"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1227","DOI":"10.1016\/j.jbiomech.2005.03.013","article-title":"The analysis of golf swing as a kinematic chain using dual Euler angle algorithm","volume":"39","author":"Teu","year":"2006","journal-title":"J. Biomech."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"171","DOI":"10.1007\/BF02844017","article-title":"Using dual Euler angles for the analysis of arm movement during the badminton smash","volume":"8","author":"Teu","year":"2005","journal-title":"Sports Eng."},{"key":"ref_3","unstructured":"Crane, C.D., Griffis, M., and Duffy, J. (2022). Screw Theory and Its Application to Spatial Robot Manipulators, Cambridge University Press."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Murray, R.M., Li, Z., and Sastry, S.S. (2017). A Mathematical Introduction to Robotic Manipulation, CRC Press.","DOI":"10.1201\/9781315136370"},{"key":"ref_5","unstructured":"Lanczos, C. (2012). The Variational Principles of Mechanics, Courier Corporation."},{"key":"ref_6","unstructured":"Ball, R. (1900). A Treatise on the Theory of Screws, Cambridge University Press. 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Available online: http:\/\/books.google.com\/books?id=J9ROAAAAMAAJ."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Shaw, R., and Turvey, M.T. (2017). Coalitions as models for ecosystems: A realist perspective on perceptual organization. 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