Sequencing of segment kinetic energy in the golf swing.

The proximal-to-distal sequence has been associated with mechanical and muscular rewards which enable high speed to be produced at the distal end of a linked system. Although the proximal-to-distal sequence has frequently been examined using analyses of segment angular velocity, analyses of segment kinetic energy can provide the most appropriate means of exploring sequential movements. However, due to methodological complexities few studies have adopted this technique. Therefore, the aim of this thesis was to determine if a sequence of segment KE was evident in the golf swing. To enable segment kinetic energy to be calculated body segment inertial parameters were estimated for 17 rigid bodies using a 30 shape geometric model. Kinematic data were then collected using a sixteen-channel Polhemus Liberty electromagnetic tracking system sampling at 240 Hz and twelve, six-degrees-of-freedom electromagnetic sensors. Using this data, total kinetic energy, calculated as the sum of the translational, local rotational and remote rotational kinetic energies was then determined for four grouped segments (Lower Body, Upper Body, Arms and Club) in the downswing phase of the golf swing. The thesis then established that the data collection technique was capable of producing reliable measures of segment KE in the golf swing. Therefore, three further studies were performed which examined the effect of club type, playing standard and weight transfer style on the sequencing of segment KE in the golf swing. In all studies, peak total segment kinetic energy increased sequentially from the proximal to the distal segment. However, the timing of peak total segment kinetic energy did not follow a proximal-to-distal sequence. Instead, peak total segment kinetic energy for the Lower Body, Upper Body and Arms occurred simultaneously at approximately 74% of the downswing, significantly earlier in the downswing than peak total Club kinetic energy which occurred just before ball contact. For skilled golfers, the results suggested that peak translational and rotational kinetic energy increased sequentially from the Upper Body to the Club. Furthermore, when the driver was used, larger magnitudes of peak translational Arms and local rotational Upper Body kinetic energies were produced and peak translational Lower Body and Upper Body KE occurred significantly later in the downswing. The results also identified that highly skilled golfers generated significantly larger magnitudes of total Arms and Club kinetic energies than less skilled golfers. Furthermore, a sequence of translational KE from the Upper Body to the Club was only produced by highly skilled players. Finally, the results indicated peak translational and local rotational Lower Body, peak translational Upper Body and peak remote rotational Arms KE occurred significantly later for the Front Foot players. In conclusion, club type, playing standard and weight transfer style had little effect on the magnitude and timing of peak total segment kinetic energy. However, significant effects were identified on measures of translational and rotational components of peak segment KE. These findings should encourage golf coaches and researchers to use analyses of segment kinetic energy rather than analyses of segment angular velocity as they are sensitive to subtle changes in technique and consider the 3D translation and rotation of body segments. The findings also highlight the importance for future analyses to consider the different weight transfer styles that exist within the golf swing.