Based on the linked source; automatically prepared and checked against the original report.
Authorship corrected
Keiichi Ishikawa and Daiki Yamasaki were omitted from the published author list and instead appeared in the acknowledgments. The corrected list includes Nadaka Hakariya, Takuya Murakami, Ishikawa, Yamasaki, Naotsugu Kaneko and Kimitaka Nakazawa. The revision also assigns specific conceptual, investigative, analytical, methodological, funding, writing, supervision and project-administration contributions across the six authors.
Experimental methods clarified
The corrected methods state that raw electromyography data were analyzed from the ball toss through serve follow-through. The movement was divided into toss, takeback, impact and follow-through events. Signals from 14 muscles were filtered, rectified, normalized to each muscle’s peak across trials and time-interpolated to 201 points for synergy analysis.
Equation and results revised
The correction replaces the muscle-synergy variance-accounted-for equation with a form beginning with one minus the normalized squared reconstruction error and restores missing in-text links for Equations 3–5. It also reports that one P2 synergy combination approximated a P1 synergy, while another P1 synergy was specific. Further results describe fractionation relationships and differing average sparseness values for P1 and P2.
