Lumbo-pelvic loading during fast bowling in adolescent cricketers: The influence of bowling speed and technique

Abstract

This study aimed to assess changes in bowling technique and lumbar load over the course of a bowling spell in adolescent fast bowlers, and to investigate the relationship between lumbar loads during fast bowling and kinematic factors which have previously been associated with low back injury. Three-dimensional motion analysis was carried out on forty participants who performed an 8-over bowling spell. There were no significant changes in bowling technique or lumbar loads over the course of the spell. Bowling with a more extended front knee, faster ball release speed and increased shoulder counter-rotation were related to increased lumbo-pelvic loading – in particular peak transverse plane rotation moments and anterior-posterior shear forces. These lumbar loads may be a factor in low back injury aetiology and future studies should investigate the relationship between lumbar loading, injury incidence and other risk factors.     

Managing pressure: patterns of appraisals and coping strategies of non-elite and elite athletes during competition

Abstract

The purpose of this study was to compare moment-to-moment appraisals and coping strategies of 4 non-elite and 2 elite male trap shooters during competitions and in particular during periods of competition perceived as critical to performance. Appraisals and coping patterns of trap shooters were captured via verbal reports of thinking provided between sets of shots during major competitions. Verbal reports were coded according to an appraisal and coping typology. Coded data as well as shooting performance data were subjected to a sequential analysis of probabilities of pairs of events. Fewer reports of negative appraisals (NEGAs) and more frequent reports of problem-focused coping (PFC) were observed among both elite athletes compared to non-elite athletes. After making a NEGA, non-elite shooters often progressed to the next target without attempting to cope, whereas elite shooters used both PFC and emotion-focused coping (EFC) before proceeding to the next target. After missing a target, the non-elite athletes used more EFC than expected. These results indicate that elite athletes are more likely to cope with NEGAs than non-elite athletes using a wider variety of coping strategies. Athletes might benefit from increased awareness of the potentially detrimental impact of NEGAs on performance and by integrating coping strategies within preparatory routines.     

The effect of biofeedback training on affective regulation and simulated car-racing performance: A multiple case study analysis

Abstract

In this study, we wished to investigate the factors that determine the direction of the spin axis of a pitched baseball. Nineteen male baseball pitchers were recruited to pitch fastballs. The pitching motion was recorded with a three-dimensional motion analysis system (1000 Hz), and the orientations of the hand segment in a global coordinate system were calculated using Euler rotation angles. Reflective markers were attached to the ball, and the direction of the spin axis was calculated on the basis of their positional changes. The spin axis directions were significantly correlated with the orientations of the hand just before ball release. The ball is released from the fingertip and rotates on a plane that is formed by the palm and fingers; the spin axis of the ball is parallel to this plane. The lift force of the pitched baseball is largest when the angular and translational velocity vectors are mutually perpendicular. Furthermore, to increase the lift forces for the fastballs, the palm must face home plate.     

Accelerometer and GPS Data to Analyze Built Environments and Physical Activity

ABSTRACT

Purpose: Most built environment studies have quantified characteristics of the areas around participants’ homes. However, the environmental exposures for physical activity (PA) are spatially dynamic rather than static. Thus, merged accelerometer and global positioning system (GPS) data were utilized to estimate associations between the built environment and PA among adults. Methods: Participants (N = 142) were recruited on trails in Massachusetts and wore an accelerometer and GPS unit for 1–4 days. Two binary outcomes were created: moderate-to-vigorous PA (MVPA vs. light PA-to-sedentary); and light-to-vigorous PA (LVPA vs. sedentary). Five built environment variables were created within 50-meter buffers around GPS points: population density, street density, land use mix (LUM), greenness, and walkability index. Generalized linear mixed models were fit to examine associations between environmental variables and both outcomes, adjusting for demographic covariates. Results: Overall, in the fully adjusted models, greenness was positively associated with MVPA and LVPA (odds ratios [ORs] = 1.15, 95% confidence interval [CI] = 1.03, 1.30 and 1.25, 95% CI = 1.12, 1.41, respectively). In contrast, street density and LUM were negatively associated with MVPA (ORs = 0.69, 95% CI = 0.67, 0.71 and 0.87, 95% CI = 0.78, 0.97, respectively) and LVPA (ORs = 0.79, 95% CI = 0.77, 0.81 and 0.81, 95% CI = 0.74, 0.90, respectively). Negative associations of population density and walkability with both outcomes reached statistical significance, yet the effect sizes were small. Conclusions: Concurrent monitoring of activity with accelerometers and GPS units allowed us to investigate relationships between objectively measured built environment around GPS points and minute-by-minute PA. Negative relationships between street density and LUM and PA contrast evidence from most built environment studies in adults. However, direct comparisons should be made with caution since most previous studies have focused on spatially fixed buffers around home locations, rather than the precise locations where PA occurs.     

Hitting the vault board: Implications for vaulting take‐off ‐ a preliminary investigation

Gymnastics vaulting relies on a specialized take‐off board for propulsion during the take‐off phase of the vault. There is little information on the vault board and its behaviour. The aim of this study was to characterize the behaviour of the vault board during handspring drill take‐offs of young male gymnasts (n = 36). The side of the top surface of the vault board and the wooden base were marked with three reflective markers, placed at the end of the vault board nearest the vault table and the centres of the two rearmost coil springs. The vault board surface was divided into two areas, rear and middle, based on marker location. The gymnasts’ groups were determined from the location of the gymnast's lateral malleolus at vault board contact. Landings with the malleolus directly above or behind the rearmost marker were considered rear landings; landings with the malleolus forward of the rearmost marker were considered middle landings. Marker movements were automatically digitized and the right malleolus was hand digitized at 120 Hz. The maximum vertical displacement, vertical deflection time, and vertical velocity at take‐off of the vault board markers did not differ statistically between board contact groups (all p > 0.05). The lateral malleolus velocity components also did not differ between board contact groups. Some low to moderately strong correlations were observed between the various marker displacements, durations and take‐off velocities. Modest correlations were obtained between board markers and right malleolus velocities. The results indicate that foot contact on the vault board, as defined here, did not result in differences in board marker behaviour or right lateral malleolus velocities. This information does not support the idea that vault board contacts at the rear of the vault board are worse than contacts near the middle of the vault board. More research is needed to ascertain the role of the vault board's vibration characteristics to whole body actions that are observed in the subsequent preflight phase.