Comparison of two- and three-dimensional methods for analysis of trunk kinematic variables in the golf swing

Aimee C Smith, Jonathan R Roberts, Eric S Wallace, Pui W Kong

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14 Citations (Scopus)
105 Downloads (Pure)


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.
Original languageEnglish
JournalJournal of Applied Biomechanics
Issue number1
Publication statusAccepted/In press - 1 Feb 2016


  • golf
  • three-dimensional
  • two-dimensional
  • X-factor
  • trunk kinematic variables


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