Aristotle's arm-swing hypothesis: biomechanical evidence from forward and inverse dynamics in an Olympic sprinter.

Introduction: Aristotle's observational hypothesis suggests that runners may run faster if they swing their arms, yet direct evidence that arm swings enhance propulsion during running is lacking. This paper aims to develop a non-VO₂-based computational pipeline to estimate propulsive and vertical impulses from pressure/force and kinematic data, and to examine whether arm-swing modification training can improve running performance. Methods: One world-class elite sprinter performed a laboratory-based arm-swing modification session on pressure treadmill. Kinematic and pressure data before and after modifications were collected by synchronized motion capture system and pressure treadmill system and analyzed with forward and inverse dynamics. Results: Results indicate that the linear displacement of the center of mass was highly consistent, and the integral changes of the Lagrangian were consistent with energy expenditure calculated by ACSM equations. The participant with modified arm swing exhibited smaller cadence, maximum ground reaction force, medial-lateral impulse integral, but increased step length and anterior-posterior and superior-inferior impulse integrals. Discussion: These results supported the observational hypothesis, which suggested that a short period of arm-swing modification training is practical to enhance running performance in laboratory settings. Moreover, digitalization, standardization, and program training protocols would enable coaches and practitioners to develop reliable interventions for improvements in running technique and athletic performance.