Validity of the X-factor computation methods and relationship between the X-factor parameters and clubhead velocity in skilled golfers.
The purpose of this study was to assess the validity of the X-factor computation methods and to examine whether direct relationships exist between the X-factor parameters and the clubhead velocity in a group of skilled male golfers (n = 18, handicap = -0.6 +/- 2.1). Five driver trials were captured from each golfer using an optical motion capture system (250 Hz). Two plane-based methods (conventional vs. functional swing plane-based) and one Cardan rotation-based method (relative orientation) were used to compute select X-factor (end of pelvis rotation, top of backswing, ball impact (BI), and maximum), X-factor stretch (stretch and maximum stretch), and X-factor velocity (BI and maximum) parameters. The maximum clubhead velocity was extracted and normalized to golfer's body height to eliminate the effect of body size. A one-way repeated MANOVA revealed that the computation methods generated significantly different X-factor parameter values (p < 0.001). The conventional method provided substantially larger X-factor values than the other methods in the untwisting phase and the meaningfulness of select X-factor parameters generated by this method was deemed questionable. The correlation analysis revealed that the X-factor parameters were not directly related to the maximum clubhead velocity (both unnormalized and normalized).
Biomechanics Laboratory, Texas Woman's University, Denton, TX 76204-5647, USA. ykwon@twu.edu
Young-Hoo
YH
Kwon
Ki Hoon
KH
Han
Christopher
C
Como
Sangwoo
S
Lee
Kunal
K
Singhal
D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena; D006055:Golf / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D008432:Mathematical Computing; D009068:Movement / Q000502:physiology; D010388:Pelvis / Q000502:physiology; D019876:Sports Equipment; D060726:Torso / Q000502:physiology; D034941:Upper Extremity / Q000502:physiology; D014741:Video Recording; D055815:Young Adult