Illeagal Arm Action And Ball Release Paper

Bowling action testingOne of our biggest challenges in building a cricket bowling sensor is determining the points for the start of the bowling action and the ball release. Wayne recently published a paper where we have managed to validate ball release determined by the accepted method (high speed video) and our inertial sensors. Its very exciting not just because of the utility of the sensors but also because its an automated method – which is a great time saver. Here is the paper details and a link to the full paper…well done Wayne and team!

Peak outward acceleration and ball release in cricket

Journal of Sport Sciences

Wayne Spratforda*, Marc Portusb, Andrew Wixtedc, Raymond Leadbetterc & Daniel A. Jamesc


The purpose of this study was to investigate the utility of peak outward acceleration (POA) measured from an inertial sensor worn at the wrist as an indicator of the critical end point of the bowling action – ball release, a critical element when assessing illegal actions. Twenty-one finger-spin and fast bowlers from nine countries were recruited from the ICC under-19 Cricket World Cup to take part in this research. Bowlers delivered a cross section of their standard deliveries while wearing an inertial sensor placed on their wrists. Ball release was determined by a validated motional analysis ball release (MABR) protocol and compared to the simultaneously collected POA. POA was shown to be highly correlated with MABR (R2 = 0.98) and a Bland–Altman plot indicated that all 148 trials were within the 3.42 frame (0.014 s) limits of agreement. POA when measured by an inertial sensor worn on the wrist during bowling had a close relationship with an established method of identifying ball release in a biomechanical laboratory regardless of bowler and delivery type. Further, accuracy can be achieved with the adoption of a simple regression equation applied to the POA and as such is a valid measure of ball release in cricket bowlers.


To cite this article: Wayne Spratford, Marc Portus, Andrew Wixted, Raymond Leadbetter & Daniel A. James (2014): Peak outward acceleration and ball release in cricket, Journal of Sports Sciences, DOI: 10.1080/02640414.2014.962577

To link to this article:

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