| Summary: | Full-body three-dimensional kinematics and ground reaction force characteristics were calculated to enable the analysis of fast bowling techniques. In particular, the effect of interactions between aspects of fast bowling technique on ball release speed and ground reaction forces. A three-dimensional full-body inverse dynamics analysis was developed allowing forces in the lower back to be estimated and their link with bowling technique addressed. The bowler was represented by a system of 18 rigid segments connected by pin joints. Kinematic (300 Hz) and kinetic (1008 Hz) data were collected for a group of 20 elite fast bowlers, using an 18 camera Vicon Motion Analysis System and a Kistler force plate. Each bowler performed six maximal velocity deliveries, striking the force plate with their front foot during the front foot contact phase of the bowling action. The best three deliveries - maximal velocity deliveries with minimal marker loss - were analysed for each bowler. The analysis was customised for each bowler using subject specific segmental properties. Parameters were calculated describing elements of fast bowling technique as well as characteristics of the ground reaction forces. The effect of these technique parameters on: ball release speed; peak ground reaction forces; and peak forces in the lower back were addressed using linear regression. The results suggest the fastest bowlers had a quicker run-up and maintained a straighter front knee throughout the front foot contact phase of the bowling action. The fastest bowlers also exhibited larger amounts of thoracic flexion, between front foot contact and ball release, and appeared to delay the onset of upper arm circumduction. These four aspects of technique explained 74% of the variation observed in ball release speed. Faster ball release speeds were associated with a larger braking impulse between front foot contact and ball release, in addition to lower peak loading rates. The results also indicate that the peak ground reaction forces and the peak forces in the lower back are determined predominantly by the initial orientation of the front leg at the instant of front foot contact.
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