Citation: WORTHINGTON, P.J., KING, M.A. and RANSON, C.A., 2013. Relationships between fast bowling technique and ball release speed in cricket.Journal of Applied Biomechanics, 29 (1) The aim of this study was to identify the key aspects of technique that characterize the fastest bowlers. Kinematic data were collected for 20 elite male fast bowlers with 11 kinematic parameters calculated, describing elements of fast bowling technique that have previously been linked to ball release speed. Four technique variables were identified as being the best predictors of ball release speed, explaining 74% of the observed variation in ball release speed. The results indicate that the fastest bowlers have a quicker run-up and maintain a straighter knee throughout the front foot contact phase. The fastest bowlers were also observed to exhibit larger amounts of upper trunk flexion up to ball release and to delay the onset of arm circumduction. This study identifies those technique variables that best explain the differences in release speeds among fast bowlers. These results are likely to be useful in both the coaching and talent identification of fast bowlers.

The relationship between bowling action classification and three-dimensional lower his item ws sumitted to voughorough niversity9s snstitutionl epository y theGn uthorF Citation: exyxD gFeF FFF et lFD PHHVF he reltionship etween owling tion lssifition nd threeEdimensionl lowerF tournl of ports ienesD PT @QAD ppF PTUEPUTF Additional Information:• his rtile ws pulished in the tournl of ports ienes ylor 8 prnis nd the definitive version is ville tX httpXGGwwwFinformworldFomGsmppGontent £ dallcontentaIHFIHVHGHPTRHRIHUHISHITUI AbstractLower back injuries, specifically lumbar stress fractures, account for the most lost playing time in professional cricket. The aim of this study was to investigate the relationship between the current fast bowling action classification system and potentially injurious kinematics of the lower trunk during fast bowling. Three-dimensional kinematic data were collected from 50 male professional fast bowlers during a standing active range of motion trial and three fast bowling trials. Seventyfour percent of the fast bowlers used a mixed bowling action attributable to having shoulder counter-rotation greater than 30°. There was no difference in the proportion of available lower trunk extension, contralateral side-flexion and ipsilateral rotation range of motion used during fast bowling by mixed and non-mixed action bowlers. The greatest proportion of lower trunk extension (26%), contralateral side-flexion (131%) and ipsilateral rotation (79%) was utilised during the front-foot contact phase of the fast bowling delivery stride. It is proposed that the combination of end range lower trunk positioning, especially side-flexion, and high ground reaction (compressive) forces during the front foot contact phase are the most important pathomechanical factors in the typical pattern of contralateral side lumbar stress injuries seen in this population.

This study used an optimization procedure to evaluate an 8-segment torque-driven subject-specific computer simulation model of the takeoff phase in running jumps for height. Kinetic and kinematic data were obtained on a running jump performed by an elite male high jumper. Torque generator activation timings were varied to minimize the difference between simulation and performance in terms of kinematic and kinetic variables subject to constraints on the joint angles at takeoff to ensure that joints remained within their anatomical ranges of motion. A percentage difference of 6.6% between simulation and recorded performance was obtained. Maximizing the height reached by the mass center during the flight phase by varying torque generator activation timings resulted in a credible height increase of 90 mm compared with the matching simulation. These two results imply that the model is sufficiently complex and has appropriate strength parameters to give realistic simulations of running jumps for height.

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This study aimed to investigate the contributions of kinetic and kinematic parameters to inter-individual variation in countermovement jump (CMJ) performance. Two-dimensional kinematic data and ground reaction forces during a CMJ were recorded for 18 males of varying jumping experience.Ten kinetic and eight kinematic parameters were determined for each performance, describing peak lower-limb joint torques and powers, concentric knee extension rate of torque development, and CMJ technique. Participants also completed a series of isometric knee extensions to measure rate of torque development and peak torque. CMJ height ranged from 0.38 -0.73 m (mean 0.55 ± 0.09 m). CMJ peak knee power, peak ankle power, and take-off shoulder angle explained 74% of this observed variation. CMJ kinematic (58%) and CMJ kinetic (57%) parameters explained a much larger proportion of the jump height variation than the isometric parameters (18%), suggesting that coachable technique factors and the joint kinetics during the jump are important determinants of CMJ performance. Technique, specifically greater ankle plantar-flexion and shoulder flexion at take-off (together explaining 58% of the CMJ height variation), likely influences the extent to which maximal muscle capabilities can be utilised during the jump.

Performing complex somersaulting skills during the flight phase of tumbling requires the generation of linear and angular momenta during the approach and takeoff phases. This paper investigates how approach characteristics and takeoff technique affect performance with a view to maximising somersault rotation in tumbling. A five-segment planar simulation model, customised to an elite gymnast, was used to produce a simulation which closely matched a recorded performance of a double layout somersault by the elite gymnast. Three optimisations were carried out to maximise somersault rotation with different sets of initial conditions. Using the same initial linear and angular momentum as the double layout somersault and varying the joint torque activation timings allowed a double straight somersault to be performed with 19% more rotation potential than the actual performance. Increasing the approach velocity to a realistic maximum of 7 ms -1 resulted in a 42% reduction in rotation potential when the activation timings were unchanged but allowed a triple layout somersault to be performed with an increase of 31% in rotation potential when activation timings were re-optimised. Increasing also the initial angular momentum to a realistic maximum resulted in a 4% reduction in rotation potential when the activation timings were unchanged but allowed a triple straight somersault to be performed with a further increase of 9% in rotation potential when activation timings were re-optimised. It is concluded that the limiting factor to maximising somersault rotation is the ability to generate high linear and angular velocities during the approach phase coupled with the ability to adopt consonant activation timings during the takeoff phase.

High ground reaction forces during the front foot contact phase of the bowling action are believed to be a major contributor to the high prevalence of lumbar stress fractures in fast bowlers. This study aimed to investigate the influence of front leg technique on peak ground reaction forces during the delivery stride. Three-dimensional kinematic data and ground reaction forces during the front foot contact phase were captured for 20 elite male fast bowlers. Eight kinematic parameters were determined for each performance, describing run-up speed and front leg technique, in addition to peak force and time to peak force in the vertical and horizontal directions. There were substantial variations between bowlers in both peak forces (vertical 6.7 ± 1.4 body weights; horizontal (braking) 4.5 ± 0.8 body weights) and times to peak force (vertical 0.03 ± 0.01 s; horizontal 0.03 ± 0.01 s). These differences were found to be linked to the orientation of the front leg at the instant of front foot contact. In particular, a larger plant angle and a heel strike technique were associated with lower peak forces and longer times to peak force during the front foot contact phase, which may help reduce the likelihood of lower back injuries.

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