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.
Bibliographical noteReference text: 1. Joyce C, Burnett A, Ball K. Methodological considerations for the 3D measurement of the X-factor and lower trunk movement in golf. Sports Biomech. 2010;9(3):206–221
2. Brown SJ, Selbie WS, Wallace ES. The X-Factor: an evaluation of common methods used to analyse major inter-segment kinematics during the golf swing. J Sports Sci. 2013;31(11):1156–1163 doi:10.1080/02640414.2013.775474. PubMed
3. Kwon Y-H, Han KH, Como C, Lee S, Singhal K. Validity of the X-factor computation methods and relationship between the X-factor parameters and clubhead velocity in skilled golfers.
Sports Biomech, 2013;12(3):231–246.
4. Zheng N, Barrentine SW, Fleisig GS, Andrews JR. Swing kinematics for male and female pro golfers. Int J Sports Med. 2008;29(12):965–970 doi:10.1055/s-2008-1038732. PubMed
5. Chu Y, Sell T, Lephart S. The relationship between biomechanical variables and driving performance during the golf swing. J Sports Sci. 2010;28(11):1251–1259 doi:10.1080/02640414.2010.507249. PubMed
6. McTeigue M, Lamb SR, Mottram R, Pirozzolo F. Spine and hip motion analysis during the golf swing. Sci. Golf II Proc. World Sci. Congr. Golf 1994.
7. McLean J. Widen the gap. Golf Mag; 1992:49–53.
8. Myers J, Lephart S, Tsai Y-S, Sell T, Smoliga J, Jolly J. The role of upper torso and pelvis rotation in driving performance during the golf swing. J Sports Sci. 2008;26(2):181–188
9. Cheetham PJ, Martin PE, Mottram RE, St. Laurent BF. The importance of stretching the ‘‘X-factor’’ in the downswing of golf: ‘‘the X-factor Stretch.’’ In: Thomas PR, ed. Optimising Performance in Golf. Brisbane, Australia; 2001:192–199. http://www.philcheetham.com/wp- content/ uploads/2011/11/Stretching-the-X-Factor-Paper.pdf
10. Zheng N, Barrentine SW, Fleisig GS, Andrews JR. Kinematic analysis of swing in pro and amateur golfers. Int J Sports Med. 2008;29(6):487–493 doi:10.1055/s-2007-989229. PubMed
11. Horan SA, Evans K, Morris N, Kavanagh J. Thorax and pelvis kinematics during the downswing of male and female skilled golfers. J Biomech. 2010;43(8):1456–1462
12. Coleman S, Anderson D. An examination of the planar nature of golf club motion in the swings of experienced players. J Sports Sci. 2007;25(7):739–748 doi:10.1080/02640410601113239. PubMed
13. Wheat JS, Vernon T, Milner CE. The measurement of upper body alignment during the golf drive. J Sports Sci. 2007;25(7):749–755 doi:10.1080/02640410601113213.
14. Winter D. Biomechanics and Motor Control of Human
Movement. New York, NY: John Willey and Sons; 1990:11–50.
15. Richards J. The measurement of human motion: A comparsion of commercally available systems. Hum Mov Sci. 1999;18(5):589–602 doi:10.1016/S0167-
16. Helwig NE, Hong S, Hsiao-Wecksler ET, Polk JD. Methods to temporally align gait cycle data. J Biomech. 2011;44(3):561– 566 doi:10.1016/j.jbiomech.2010.09.015. PubMed
17. Alkjaer T, Simonsen EB, Dyhre-Poulsen P. Comparison of inverse dynamics calculated by two- and three-dimensional models during walking. Gait Posture. 2001;13(2):73–77
http://www.ncbi.nlm.nih.gov/pubmed/11240354. PubMed doi:10.1016/S0966-6362(00)00099-0
18. Cook C, Showalter C. A survey on the importance of lumbar coupling biomechanics in physiotherapy practice. Man Ther. 2004;9(3):164–172 doi:10.1016/j.math.2004.03.003.
19. Huijbregts P. Lumbar spine coupled motions : A literature review with clinical implications. Orthop. Div. Rev. 2004:21–25. http://www.shelbournephysio.ca/images/uploads/79/coupledmo
20. Kwon Y-H, Como CS, Singhal K, Lee S, Han KH. Assessment of planarity of the golf swing based on the functional swing plane of the clubhead and motion planes of the body points.
Sports Biomech. 2012;11(2):127–148. PubMed doi:10.1080/14763141.2012.660799
21. Tinmark F, Hellström J, Halvorsen K, Thorstensson A. Elite golfers’ kinematic sequence in full-swing and partial-swing shots. Sports Biomech. 2010;9(4):236–244
- trunk kinematic variables