Test-retest reliability of segment kinetic energy measures in the golf swing.

Analyses of segment kinetic energy (KE) can provide the most appropriate means of exploring sequential movements. As the reliability associated with its measurement has not been reported, the aim of this study was to examine the test-retest reliability of segment KE measures in the golf swing. On two occasions, seven male golfers hit five shots with three different clubs. Body segment inertia parameters were estimated for 17 rigid bodies and 3D kinematic data were collected during each swing. The magnitude and timing of peak total, linear and angular kinetic energies were then calculated for each rigid body and for four segment groups. Regardless of club type, KE was measured with high reliability for almost all rigid bodies and segment groups. However, significantly larger magnitudes of peak total (p = 0.039) and linear (p = 0.021) lower body KE were reported in test 2 than in test 1. The high reliability reported in this study provides support for the use of analyses of segment kinetic energy. However, practitioners should pay careful attention to the identification of anatomical landmarks which define the thigh, pelvis and thorax as this was the main cause of variability in repeated measures of segment kinetic energy.

The Difference in Neuromuscular Fatigue and Workload During Competition and Training in Elite Cricketers.

PURPOSE: First, to assess changes in neuromuscular function via alterations in countermovement-jump strategy after training and 2 forms of competition and second, to compare the relationship between workloads and fatigue in seam bowlers and nonseam bowlers. METHODS: Twenty-two professional cricketers' neuromuscular function was assessed at baseline, immediately post and +24 h posttraining, and after multiday and 1-day cricket events. In addition, perceptual (rating of perceived exertion [RPE] and soreness) measures and external loads (PlayerLoad™, number of sprints, total distance, and overs) were monitored across all formats. RESULTS: Seam bowlers covered more distance, completed more sprints, and had a higher RPE in training (P < .05), without any difference in soreness compared with nonseam bowlers. Compared with seam bowlers, the nonseam bowlers' peak force decreased post-24 h compared with baseline only in 1-d cricket (95% CI, 2.1-110.0 N; P < .04). There were no pre-post training or match differences in jump height or alterations in jump strategy (P > .05). Seam bowlers increased their peak jumping force from baseline to immediately posttraining or game (95% CI, 28.8-132.4 N; P < .01) but decreased between postcricket to +24 h (95% CI, 48.89-148.0 N; P < .001). CONCLUSION: Seam bowlers were more accustomed to high workloads than nonseamers and thus more fatigue resistant. Changes in jump height or strategy do not appear to be effective methods of assessing fatigue in professional crickets. More common metrics such as peak force are more sensitive.