title: Comparison of Two- and Three-Dimensional Methods for Analysis of Trunk Kinematic Variables in the Golf Swing.
abstract: Two-dimensional methods have been used to compute trunk kinematic variables (flexion/extension, lateral bend, axial rotation) and X-factor (difference in axial rotation between trunk and pelvis) during the golf swing. Recent X-factor studies advocated three-dimensional (3D) analysis due to the errors associated with two-dimensional (2D) methods, but this has not been investigated for all trunk kinematic variables. The purpose of this study was to compare trunk kinematic variables and X-factor calculated by 2D and 3D methods to examine how different approaches influenced their profiles during the swing. Trunk kinematic variables and X-factor were calculated for golfers from vectors projected onto the global laboratory planes and from 3D segment angles. Trunk kinematic variable profiles were similar in shape; however, there were statistically significant differences in trunk flexion (-6.5 ± 3.6°) at top of backswing and trunk right-side lateral bend (8.7 ± 2.9°) at impact. Differences between 2D and 3D X-factor (approximately 16°) could largely be explained by projection errors introduced to the 2D analysis through flexion and lateral bend of the trunk and pelvis segments. The results support the need to use a 3D method for kinematic data calculation to accurately analyze the golf swing.
authors.affiliation: Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, UK.
authors.forename: Aimée C
authors.initials: AC
authors.lastname: Smith
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Roberts
authors.forename: Eric S
authors.initials: ES
authors.lastname: Wallace
authors.forename: Pui
authors.initials: P
authors.lastname: Kong
authors.forename: Stephanie E
authors.initials: SE
authors.lastname: Forrester
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena / Q000502:physiology; D006055:Golf / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D009068:Movement / Q000502:physiology*; D010388:Pelvis / Q000502:physiology*; D012399:Rotation; D060726:Torso / Q000502:physiology*