Abstract
Golf swing analysis is common in both recreational and professional levels where players are searching for improvements in shot accuracy and distance. The use of motion analysis systems such as the portable Polhemus Liberty system is gaining interest by coaches and players; however, to date, no research has examined the usefulness of the Polhemus Liberty system for golf swing analysis. Therefore, the purpose of this study was to determine the reliability of the Polhemus Liberty system and validity compared to the VICON Nexus motion analysis system when assessing segment (pelvis and thorax) and joint (shoulder, elbow and wrist) angular kinematics during a golf swing at key events (address, top of backswing and impact). Fifteen elite amateur/professional golfers performed ten golf swing trials within specified bounds using their 5-iron club. Reliability was assessed using interclass coefficient, effect size and t-test statistics by all participants completing two separate testing sessions on separate days following the same experimental protocol. Validity was assessed using effect size, Pearson correlation and t-test statistics by comparing swings captured using both Polhemus Liberty and VICON Nexus concurrently. Results demonstrated no difference in ball outcome results using the Trackman launch monitor (P > 0.05) and that the Polhemus Liberty system was reliable across the two sessions for all segment (pelvis and thorax) and joint (lead shoulder (gleno-humeral joint), elbow and wrist) angular kinematics (P > 0.05). Validity analysis showed that the Polhemus Liberty system for the segments (pelvis and thorax) and joints (lead shoulder and wrist) were different compared to the VICON Nexus data at key events during the golf swing. Although validity could not be confirmed against VICON Nexus modeling, the Polhemus Liberty system may still be useful for golf swing analysis across training sessions. However, caution should be applied when comparing data from the system to published research data using different motion analysis methods.
Highlights
The longitudinal axis demonstrated poor ICCs (0.0) for all events; the mean differences ranged from 0.4–0.5◦
The current study indicated an overall moderate-good test retest reliability for all Polhemus Liberty system segments and joint angular kinematics at address, top of backswing and impact events of the golf swing
Whilst validity results of the current study indicated differences between Polhemus Liberty and VICON, there was some correlation among segment and joint angular kinematics for left wrist lateral deviation at address, and thorax rotation at the top of backswing
Summary
Golf is considered a sport played predominately by older adults; recently, there has been an increased effort across golfing bodies, professional athletes and golf clubs to recruit younger players and connect with a larger scope of the general public with the particular target of drawing interest and increasing the appeal of the game [2]. As participation in competition increases, so too does high-level performance demand, requiring advancements in training programs and analysis methodologies [3]. Performance analysis and recovery have been employed by athletes and their support teams. The development of training interventions and analysis has rapidly evolved over recent years with more elite amateurs and professionals employing the services of sports biomechanics, strength and conditioning coaches, sports psychologists and physiotherapists to their coaching teams. The proliferation of analysis and training interventions has been further reinforced through players constantly seeking to gain advantage over fellow competitors to increase their opportunities to win major tournaments, improve their ranking status and increase prizes [3]
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