Biomechanical, anthropometric, and isokinetic strength characteristics of elite finger and wrist-spin cricket bowlers: A developmental and performance perspective

Wayne Anthony Spratford

    Research output: ThesisDoctoral Thesis

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    Abstract

    Spin bowling can be classified into two main categories, with bowlers either having a finger-spin (FS) or wrist-spin (WS) action, a definition referring to the body endpoint segment motion primarily responsible for placing revolutions on the ball. In general, the spin bowler delivers the ball significantly slower than their fast bowling counterpart, relying on deviations during flight (drift and dip) and after bounce (side-spin) to influence the contest. Using a single measure of performance such as ball release (BR) velocity, as is common in fast bowling research, fails to take into account the many variables required for spin bowling success. These include placing revolutions on the ball, as well as appropriately directing the axis of rotation and orientating the seam of the ball. In order to optimise these variables, the spin bowler must deliver the ball with the appropriate revolutions and BR velocity created through a series of complex and rapid upper-body movements between back foot impact (BFI) and BR.

    While some attempts have been made to measure initial ball flight kinematics in both FS and WS bowlers, to date no research has attempted to quantify ball seam location during flight. Research exploring the biomechanical aspects ofspin bowling has also received limited attention, with only a single study attempting to explore the kinematics of FS bowlers and its relationship to ball velocity and revolutions. Therefore, the aim of this thesis was to advance our understanding of ball and upper-body kinematics for both FS and WS bowlers,and to extend this knowledge to include upper-body kinetics and underlying physical attributes (e.g., anthropometry and isokinetic strength) in bowlers with varying expertise. This was achieved through a series of four connected research studies (chapters four, five, six and seven). For each study, bowlers were stratified into pathway (FS n=24, WS n=12) or elite (FS n=12, WS n=8)groups reflective of their playing level with ball kinematics and upper-bodymechanics calculated. For studies two and three, anthropometry and isokinetic strength data were collected and compared with performance measures identified in study one. Study four (chapter seven), included a cohort of 12 FS bowlers, who exhibited an illegal bowling action that precluded them from the initial three studies (pathway illegal).

    Results from study one (chapter four) indicated that when comparing ball kinematics between FS and WS bowlers, FS bowlers delivered the ball with an increased axis of rotation elevation angle, while WS bowlers imparted greater revolutions on the ball. These differences reflect the bowling strategies adopted by each type of bowler, with FS bowlers relying on flight and drift compared with WS bowlers who appear to rely on increased side-spin rates. When comparing between skill levels within each bowling type, elite FS and WS bowlers recorded increased BR velocity, revolutions and velocity/revolution indices. Elite FS bowlers displayed an increased seam stability measure, while seam azimuth and spin axis elevation angles were greater in elite WS bowlers compared with pathway bowlers. These findings identify a number of ball kinematic measures that appear to be useful in distinguishing between skill level for both FS and WS bowlers. From an applied perspective, these differences identified between skill levels will likely influence the ball flight characteristics both in flight (drift anddip), as well as post bounce (angle of ball bounce and direction of side-spin).

    Studies two (FS) and three (WS) (chapters five and six) adopted the velocity/revolution index, developed in study one as a discriminator of performance across bowler types. Results from study two, indicated that elite FS bowlers make better use of the degrees of freedom (DoF) within the kinetic chain by rotating their trunks (thorax and pelvis) and extending their elbow joint through the point of BR. When the data from both the elite and pathway cohorts were combined and a regression analysis performed, results revealed that isokinetic extension/adduction strength of the shoulder; peak metacarpophalangeal (MCP) flexion angle, ulna deviation angular velocity at BR and the linear velocity of the wrist joint centre were the best predictors of performance. These results highlighted the importance of the trunk early within the bowling phase and the subsequent movements at the distal arm (elbow, wrist and MCP joints) through the point of BR.

    When comparing elite and pathway WS bowlers (study three), elite bowlers displayed lower levels of trunk rotation about the long axis (anti clockwise for a right hand bowler) between BFI-BR, delivered the ball in a more front-onposition, but exhibited increased forward pelvis rotation angular velocity at BR. They also displayed an increased peak shoulder internal rotation moment, as the shoulder moved from external rotation into internal rotation. This internal rotation movement was subsequently responsible for the kinetic and kinematic differences observed at the elbow (pronation) and wrist (ulna deviation and extension) through better utilisation of the DoF within the body’s kinetic chain.Elite bowlers also exhibited anthropometry variations at the wrist (active radial deviation and total range in the frontal plane); hand (length) and phalange (MCP4 flexion and extension range of motion) that may be used to form the basis of talent identification (TID) protocols. When the data from both the elite and pathway cohorts were combined and a regression analysis performed, peak isokinetic radial deviation torque, peak shoulder internal rotation moment, the shoulder extension moment at BR and the peak elbow pronation moment were the best predictors of performance (velocity/revolution index). These results highlighted the importance of baseline upper arm strength and the long axis rotations of the bowling limb, particularly shoulder internal rotation, in what is considered the most technically demanding form of cricket bowling.

    During data collection a cohort of FS bowlers (n=12) were identified with illegal bowling actions. In an attempt to understand if illegal actions influence performance as measured by ball revolutions and ball velocity (variables identified in study one), were again used to compare this pathway illegal group with the existing legal pathway and elite FS bowlers (no data were collected on illegal elite FS bowlers). Results indicated that the pathway illegal cohort performance variables reflected that of the more experienced elite legal group, providing evidence that a performance benefit of ball revolutions and velocity were apparent when elbow extension levels exceed regulation thresholds. To examine if differences, other than elbow extension were present, a range of additional upper-body kinematics were compared between the pathway illegal and elite legal bowlers. These results highlighted that pathway illegal bowlers displayed a more front-on delivery technique at BFI and BR, and relied on increased amounts of elbow flexion and supination in the lead up to BR. Subsequently, pathway illegal bowlers exhibited increased amounts of elbow extension and wrist flexion angular velocity to the detriment of ulna deviation angular velocity. Results suggest that coaching staff should encourage a more side-on technique at BFI and encourage bowlers to rotate their trunks through to the point of BR, when attempting to remediate illegal bowling actions.

    In summary, these four studies have advanced the understanding of both FS and WS bowling across the development pathway and identified ball kinematic measures that can be used to discriminate between skill levels. Further, we have identified kinematic, kinetic and isokinetic strength measures that are critical in both FS and WS bowling and as such should form the basis for coaching and conditioning programs. Finally, this research is the first experimental study to report a performance benefit when FS bowlers deliver the ball with an illegal action. Recommendations have also been provided that maybe used to assist bowlers in remediating an illegal bowling technique.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2015

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