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.

The required number of trials for biomechanical analysis of a golf swing

“…The static trial provided the 0° segment and joint orientations for the local coordinate systems (Kawamoto, Miyagi, Ohashi, & Fukashiro, 2007). Trunk and hip motions are common focus points of biomechanical analyses in golfing tasks (Gulgin et al, 2009;Hara et al, 2016;Joyce et al, 2013;Smith et al, 2016), and were therefore selected for this study. Thus, kinematic variables of interest were the three-dimensional range of motion (ROM) and velocity of the hips and trunk.…”

“…The golf swing has been of particular interest for biomechanical researchers, who traditionally collect data from volunteers performing a designated number of trials (Egret, Vincent, Weber, Dujardin, & Chollet, 2003;Gulgin, Armstrong, & Gribble, 2009;Hara et al, 2016). The number of trials collected in golf research has varied greatly, and ranges from two (Meister et al, 2011) to twelve (MacKenzie, Ryan, & Rice, 2015), with many studies using five (Horan, Evans, & Kavanagh, 2011;Horan, Evans, Morris, & Kavanagh, 2010;Zheng, Barrentine, Fleisig, & Andrews, 2008) or ten trials (Egret et al, 2003;Smith, Roberts, Kong, & Forrester, 2017;Smith, Roberts, Wallace, Kong, & Forrester, 2016).…”

Movement Analysis of the Golf Swing

“…The equivalence may reflect a range of methodological differences between studies. For example, X-factor and trunk kinematic (flexion/extension, lateral bend, axial rotation) variables may be quite different when calculated by 2D compared to 3D methods (Smith, Roberts, Wallace, Pui, & Forrester, 2016). Differences between 2D and 3D X-factor (~16°) results can be explained by projection errors introduced to 2D analysis through trunk flexion (-6.5 ± 3.6°) at the top of the backswing and trunk right-side lateral bend (8.7 ± 2.9°) of the trunk and pelvis segments at impact.…”

Kinematic determinants of performance parameters during golf swing

“…As golf itself is a three-dimensional (3D) activity, 3D motion analysis is preferred for golf research as it can accurately analyse body and joint movements during golf swings. 2,10 There have been various methods for investigating the X-Factor based on data collection using either video cameras 11 or an optical motion capture system. 3,4,10,[12][13][14][15] Most studies have computed the X-Factor from the shoulder line and hip lines on the projected transverse plane.…”