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Fast bowling is categorised into four action types: side-on, front-on, semi-open and mixed; however, little biomechanical comparison exists between action types in junior fast bowlers. This study investigated whether there are significant differences between action-type mechanics in junior fast bowlers. Three-dimensional kinematic and kinetic analyses were completed on 60 junior male fast bowlers bowling a five-over spell. Mixed-design factorial analyses of variance were used to test for differences between action-type groups across the phases of the bowling action. One kinetic difference was observed between groups, with a higher vertical ground reaction force loading rate during the front-foot contact phase in mixed and front-on compared to semi-open bowlers; no other significant group differences in joint loading occurred. Significant kinematic differences were observed between the front-on, semi-open and mixed action types during the front-foot contact phase for the elbow and trunk. Significant kinematic differences were also present for the ankle, T12-L1, elbow, trunk and pelvis during the back-foot phase. Overall, most differences in action types for junior fast bowlers occurred during the back-foot contact phase, particularly trunk rotation and T12-L1 joint angles/ranges of motion, where after similar movement patterns were utilized across groups during the front-foot contact phase.

BackgroundInjury prevention programmes (IPPs) are effective in reducing injuries among adolescent team sports. However, there is no validated cricket-specific IPP despite the high incidence of musculoskeletal injuries among amateur cricketers.ObjectivesTo evaluate whether a cricket injury prevention programme (CIPP) as a pretraining warm-up or post-training cool-down can reduce injury rates in amateur cricket players.MethodsCIPP is a cluster randomised controlled trial which includes 36 male amateur club teams having cricket players aged 14–40 years to be randomly assigned to three study arms: warm-up, cool-down and control (n=12 teams, 136 players in each arm). The intervention groups will perform 15 min CIPP either as a pretraining warm-up or a post-training cool-down.Outcome measuresThe primary outcome measure will be injury incidence per 1000 player hours and the secondary outcome measures will be whether IPP as a warm-up is better than IPP as a cool-down, and the adherence to the intervention.Trial registration numberACTRN 1261700047039.

Due to the high incidence of lumbar spine injury in fast bowlers, international cricket organisations advocate limits on workload for bowlers under 19 years of age in training/matches. The purpose of this study was to determine whether significant changes in either fast bowling technique or movement variability could be detected throughout a 10-over bowling spell that exceeded the recommended limit. Twenty-five junior male fast bowlers bowled at competition pace while three-dimensional kinematic and kinetic data were collected for the leading leg, trunk and bowling arm. Separate analyses for the mean and within-participant standard deviation of each variable were performed using repeated measures factorial analyses of variance and computation of effect sizes. No substantial changes were observed in mean values or variability of any kinematic, kinetic or performance variables, which instead revealed a high degree of consistency in kinematic and kinetic patterns. Therefore, the suggestion that exceeding the workload limit per spell causes technique- and loading-related changes associated with lumbar injury risk is not valid and cannot be used to justify the restriction of bowling workload. For injury prevention, the focus instead should be on the long-term effect of repeated spells and on the fast bowling technique itself.

Active drag force in swimming can be calculated from a function of five different variables: swim velocity, tow velocity, belt force, power output and exponent of velocity. The accuracy of the drag force value is dependent on the accuracy of each variable, and on the contribution of each variable to drag estimation. To calculate uncertainty in drag value, first the derivatives of the active drag equation with respect to each variable were obtained. Second, these were multiplied by the uncertainty of that variable. Twelve national age and open level swimmers were recruited to complete four free swimming and five active drag trials. The uncertainties for the free and the tow swim velocities, and for the belt force, contributed approximately 5-6% and 2-3% error, respectively, in calculation of drag. The result of the uncertainty of the velocity exponent (1.8-2.6) indicated a contribution of about 6% error in active drag. The contribution of unequal power output showed that if a power changed 7.5% between conditions, it would lead to about 30% error in calculated drag. Consequently, if a swimmer did not maintain constant power output between conditions, there would be substantial errors in the calculation of active drag.

Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p

The reliability of active drag values was examined using a method that compared free swim speed with measurements taken by towing swimmers slightly faster than their maximum swim speed, while allowing their intra-stroke speed fluctuations. Twelve national age and open level swimmers were tested on two alternate days (Day 1 and Day 2). All participants completed four maximum swim speed, three passive drag and five active drag trials on each of the days. The reliability was determined using within-participant intra-class correlation coefficients (ICC) within each day and between the days. The ICCs for Day 1 and Day 2 were 0.82 and 0.85, respectively, while the comparison of the mean active drag values between days was 0.93. The data showed that the assisted towing method (ATM) with fluctuating speed was only moderately reliable within a single test. However, this method was more reliable when using the average value of active drag from both days (ICC = 0.93). This study identified that the ATM method with fluctuating speed had moderate reliability within-participant trials on values in a single day but high reliability for the average active drag values across different days.

At the turn of the century, a new format of cricket [Twenty20 (T20)] was introduced that has led to more matches being played. Since then, it has been debated whether T20 cricket has increased the risk of overuse injuries. The primary aim of this study was to meta-analyse the cricket injury rates in the twenty-first century. The secondary aims were to explore the risk factors and mechanisms of injury by analysing correlates such as age, format, era of play, country, player type, etc., and to conduct a qualitative analysis of the published studies. Several databases were searched using keywords “cricket” and “injur*” and 24 papers reporting cricket injuries fitted the inclusion criteria. Fifteen papers included data on exposure time and were used to calculate injury rates to perform sub-group analysis. Pooled data on 12,511 players revealed 7627 injuries, and the 1.12 million hours of cricket play from 15 studies reporting exposure time showed an injury rate of 53.16 (95% confidence interval 51.84–54.52) per 10,000 h of play. There were no statistically significant differences in injury rates based on age, format, era of play, country, player type and injury definitions. Bowling biomechanics and workload were identified as the major risk factors for bowling injuries. This review shows that injury rates in junior and amateur cricket are higher than the injury rates of comparable cohorts playing other popular non-contact or quasi-contact team sports. There is not enough evidence to conclude that T20 cricket has increased injury rates.

Background The grade cricket competition, also known as premier cricket, supplies players to the state and national teams in Australia. The players involved are generally high-performing amateur (subelite) club cricketers. However, to date, there is no study on the injury epidemiology of Australian grade cricket. Aim To conduct injury surveillance across all teams playing Sydney Grade Cricket (SGC) competition during the 2015–2016 season. Methods A cohort study was conducted to track injuries in 408 male cricketers in 20 teams playing SGC competition. Players were tracked through the MyCricket website’s scorebook every week. Cricket New South Wales physiotherapists were alerted if there were changes to the playing XI from the last game. If any changes were made due to injury, then an injury incident was registered. Results During the course of the season, a total of 86 injuries were registered from 65 players, resulting in a loss of 385 weeks of play. The overall injury incidence rate was 35.54 injuries/10 000 playing hours with an average weekly injury prevalence of 4.06%. Lower back injuries (20%) were the most common injuries followed by foot (14%), hand (13.75%), knee (7.5%) and calf (7.5%). Linear regression analysis showed that the likelihood of injury increased as the mean age of the teams increased (R=0.5, p Conclusion The injury rate in SGC is lower than that reported at elite level. However, the high rate of lower back injuries (20%) highlights an area of concern in this cohort. High workloads or inadequate physical conditioning may contribute to such injuries. This study sets the foundation for understanding injury epidemiology in grade cricket and examines the links between injury and performance, these results may assist coaches and administrators to develop and implement cricket-specific injury prevention programmes.

In off-spin bowling (finger-spin delivery with a sidespin, right-handed bowler), the ball rolls over the middle finger and rotates counterclockwise, as seen by the batsman. It is therefore expected that the torque imparted onto the ball is generated by the middle finger and the centre of pressure (COP) is also located close to the middle finger. The off-spin bowling action was recorded in five bowlers with a smart cricket ball and the COP was determined. In two bowlers, the COP was located at the middle finger and moved clockwise, i.e. against the sense of the ball, inherent to rolling motion. In one bowler, the COP was shifted slightly to the index finger, indicating a small contribution by the index to torque generation. Another bowler initiated the torque generation with the index finger, and then the COP moved from index to middle finger. The fifth bowler produced a rare case of braking i.e. deceleration of the ball at release, with the tip of the index finger, as seen in the location of the COP. In this case, the COP moved from the middle finger to the index. This preliminary study of off-spin bowling contributes to the understanding of torque generation, confirming that the primary torque generation is by the middle finger, a mechanism that could be more effective when combined with the torque generation by the index finger.

In this study, a three-dimensional (3D) dynamics model of the human body was developed to analyze the motion of fast bowling in cricket. Nine fast bowlers (22.4 ± 3.2 years) were selected from high-level regional cricket to bowl a series of balls at a target placed approximately on a ‘good length’ in line with the wickets, while their bowling actions were captured by a 10-camera 240 Hz motion analysis system (Motion Analysis Corp.). Motion analysis data were obtained from the tracked markers on the bowler strategically placed on the body to define a 3D joint coordinate system for each segment. Two Bertec force plates were used to measure the ground reaction forces. The resulting kinematic and force plate data of the fastest ball were fed into a computer model designed using the Mechanical Systems Pack (Wolfram Research, Inc., V. 5.2), a set of Mathematica packages written for the analysis of spatial rigid body mechanisms, implementing a dynamics formulation with Lagrangian multipliers. The computer model gave a 3D representation of the human body as a system of 15 rigid body segments with mass and inertia properties. Inverse solution dynamics were calculated to generalize certain fundamental aspects of the pelvis, thorax and bowling arm during fast bowling. How to cite this article Ferdinands R. Kinetics Analysis of Pelvis, Thorax, and Bowling Arm in Cricket Bowling. J Postgrad Med Edu Res 2015;49(4):159-163.

As torque is imparted on a cricket ball before release, the spin vector precesses into the torque vector. Normalising the precession speed to the torque and the angular velocity yields the ‘normalised precession’, i.e. the angle between the spin vector and the torque vector. The maximal normalised precession was analysed in spin bowling, specifically in finger- and wrist spin, and topspin, sidespin and backspin deliveries. The data were recorded with a smart cricket ball and a Cortex motion analysis system. The maximal normalised precession at the beginning of the finger torque increased from topspin to backspin. The reason for this behaviour is that the motion of the bowling arm imparts a topspin on the ball, and therefore the spin axis does not have to change its direction if the fingers impart further topspin on the ball.

The techniques of spin bowling in cricket have been largely formulated from the collective intuitions of past players. A standard model of bowling technique has been generally prescribed for both off-spin and leg-spin bowlers, but there has been no biomechanics research to validate this approach. This study measured 20 Type-2 off-spin and 15 Type-2 leg-spin bowlers using a 3D Cortex motion analysis system. Correlation coefficients between segmental kinematic variables and spin rate in the off-spin and leg-spin bowlers revealed that off-spin bowling was associated with an earlier movement time of the thorax, whereas leg-spin bowling was associated with a greater magnitude and earlier movement time of pelvis rotation, as well as a greater magnitude of pelvis-shoulder separation movement. The maximum velocity of rear hip flexion differentiated between both groups of bowlers. The GLM suggested that for off-spinners, rear hip flexion velocity significantly explained the variance in spin rate (subject to sequential timing constraints), while for leg-spinners, the time of maximum rear hip flexion and maximum arm circumduction velocity significantly explained variance in spin rate. This study supports the notion that off-spinners and leg-spinners have significant differences in their joint kinematics, and should not be coached under a one-size-fits-all technical model.

Throwing carries an inherent risk of injury that worsens in the presence of arm fatigue. The purpose of this study was to identify markers that could facilitate the early detection of this type of fatigue, by comparing the response to bouts of throwing-specific and running-based exercise. Thirteen elite junior male baseball players were tested twice, 7 days apart with a randomized crossover design. They were assessed for shoulder proprioception, maximal throwing velocity, and throwing accuracy before and after a 10-minute bout of either throwing-specific (THROW) or general (RUN) exercise. Maximal throwing velocity was reduced similarly after both THROW and RUN bouts (-1.0 ± 0.4 vs. -0.6 ± 0.2 m·s-1, respectively; p

The purpose of this study was to analyse the kinematics and kinetics of the rear leg drive in fast bowling, and then investigate whether any of these variables were associated with ball release speed. Eighteen young fast bowlers (17.2 ± 1.7 years) were recruited from the Cricket New South Wales development squad, and their bowling actions were captured by a Cortex 2.0 motion analysis system (200 Hz). Bivariate Pearson's product-movement correlation coefficients were calculated in SPSS (Version 17.0) to assess the relationships between wrist speed (of the bowling hand) and the kinematics and kinetics variables corresponding with rear leg motion. A number of kinematic variables were correlated with bowling wrist speed, most of them during the delivery stride, including mean thigh extension angular velocity (r = 0.606, p = 0.008), thigh adduction angular velocity at back foot contact (r = 0.515, p = 0.029) and maximum change in knee extension angular velocity (r = 0.559, p = 0.016). This study also showed th...

The mixed bowling action is associated with injuries in the lumbar spine and has been shown to have no performance benefits over other bowling actions. The purpose of this study was to assess the mixed bowling action with reference to a more comprehensive classification system to facilitate the development of more targeted bowling action remediation programs. A total of 70 fast bowlers were tested using a three-dimensional motion analysis system (240 Hz). Kinematic data of the shoulders and pelvis were analysed with respect to a modified set of angle threshold criteria to classify bowling actions. It was found that the mixed action bowlers (49% of the sample) could be sub-divided into seven distinct mixed action types. The most common of these types were the mixed front-on bowlers with respect to shoulder counter-rotation (19%) and the mixed front-on bowlers with respect to both pelvis-shoulder separation angle and shoulder counter-rotation (14%). It is envisaged that a more comprehensive classification o...

The purpose of this study was to analyse the performance outcomes of spin bowlers by using a motion analysis procedure to measure the linear and angular kinematics of a spinning ball. A three-dimensional (3D) Cortex motion analysis system was used to track three markers strategically placed on the ball spinning in flight. Data were further processed using 3D vector kinematics to calculate the ball's linear speed, spin rate and direction of the angular velocity vector. Thirty-four district-level spin bowlers, including both finger-spinners and wrist-spinners, were recruited to bowl 20 standard deliveries, and 5 deliveries of any variation in their repertoire. The results show that spin bowlers can produce various combinations of spin rate and angular velocity vector orientations to implement substantially different methods of utilising both swerve and turn off the pitch to deceive the batsman. In particular, it was found that wrist-spin bowlers could potentially swerve the ball either towards the left or r...

Some previous research indicates that compared to dynamics stretching, static stretching may inhibit the performance of the instep kick, but the effect of these two modes of stretching on soccer players with differing levels of playing experience is not known. Hence, the purpose of this study was to examine the effects of static and dynamic stretching during pre-exercise warm-up on lower extremity kinematics during soccer instep kicking in less and more experienced players. Twenty-four professional male soccer players (12 less experienced and 12 more experienced players) volunteered to participate. Lower extremity joint kinematics of soccer instep kicking were analyzed after static stretching, dynamic stretching, and no-stretching warm-up protocols. The kinematic variables analyzed were the maximum hip angular velocity and maximum knee angular velocity during the leg acceleration phase, and maximum ball velocity after impact phase. Relative to the no-stretching condition, both less and more experienced pl...

Although there have been many studies to quantify the segmental sequencing in other sports, there has been little such research applied to cricket bowling. In this study, 34 fast bowlers (22.3 ± 3.7 years) of premier grade level and above were tested using 3D motion analysis, their balls speed ranging from 27.0 to 35.6 m s− 1. One-way repeated measures ANOVA was used to test for within-participant differences in segmental sequencing based on the timings of maximum segmental angular velocities and kinetic energies, the data showing that bowlers exhibited a general order of proximal-to-distal sequencing. Bivariate Pearson's product-movement correlation coefficients were calculated to assess the relationships between kinematic variables and ball release speed, yielding a set of variables for entry into a stepwise multiple regression model. The multiple regression model with the sequential timing variables of thoracic linear kinetic energy (KE), upper-arm circumduction velocity and forearm rotation KE, as wel...

This preliminary study aimed to quantify the magnitude of the peak shoulder distraction force during the bowling action of female cricket fast bowlers. An eight camera Vicon motion analysis system operating at 120 Hz recorded the fast bowling actions of 18 Australian female fast bowlers. A three segment inverse solution model of the bowling arm was used to calculate the shoulder distraction force. A large peak shoulder distraction force was recorded during the early stages of the follow-through of the bowling action. When normalized for body weight, the distraction force was within the range of values reported for baseball and softball pitchers, who are considered to be at high risk of shoulder injury. Therefore, the relative importance of the peak shoulder distraction force in the fast bowling action for the development of shoulder pain in female cricket fast bowlers warrants further investigation.

This study aimed to investigate the bowling techniques of female fast bowlers and identify any association between a history of low back pain (LBP) and the movement patterns of the thorax relative to the pelvis during the delivery stride of the bowling action. Three-dimensional kinematic data were collected from 26 elite Australian female fast bowlers using an eight-camera Vicon motion analysis system. Nineteen bowlers used a mixed action, 6 bowlers used a semiopen action, and 1 bowler used a side-on action. Fourteen bowlers had a history of LBP. Eight of these 14 bowlers used a mixed action, and bowlers with more shoulder counterrotation were no more likely to have a history of LBP. Bowlers with a history of LBP positioned the thorax in more left lateral flexion relative to the pelvis between 73–79% of the delivery stride, and moved the thorax through a significantly greater range of lateral flexion relative to the pelvis during the delivery stride compared with bowlers with no history of LBP. This information will give coaches and support staff a better understanding of female bowling technique and may facilitate better screening practices for elite female cricketers.

Release velocity and accuracy are vital components of throwing performance. However, there is no published research on these parameters for throwing in cricket. In this study, we investigated the throwing performance of 110 cricket players from six different populations: elite senior males, elite under-19 junior males, elite under-17 junior males, elite senior females, elite under-19 junior females, and sub-elite senior males. Based on a specifically designed cricket throwing test, participants were assessed for (1) maximal throwing velocity and (2) throwing accuracy at maximal velocity and at three sub-maximal velocities. Elite senior males exhibited the highest peak and mean maximal throwing velocities (P≤0.001). Furthermore, the groups of males had significantly higher peak and mean maximal throwing velocities than the groups of females (P≤0.01). A speed–accuracy trade-off existed such that all groups demonstrated improved accuracy scores at velocities between 75% and 85% maximal throwing velo...

The speed-accuracy trade-off in throwing has been well described, but its cause is poorly understood. The popular impulse-variability hypothesis lacks relevance to throwing, while the launch window hypothesis has explanatory potential but has not been empirically tested. The current study therefore aimed to quantify the speed-accuracy trade-off and launch window during a throwing task at two different speeds. Nine elite junior baseball players (M age = 19.6 yr.; M height = 1.80 m; M weight = 75.5 kg) threw 10 fastballs at 80 and 100% of maximal throwing speed (MTS) toward a 7 cm target from a distance of 20 m. A 3D motion analysis system measured ball speed and trajectory. A speed-accuracy trade-off occurred, mediated by increased vertical error. This can be attributed to the launch window, which was significantly smaller, particularly its vertical component, during 100% MTS. Maximal throwing speed correlated negatively with launch window size. The launch window hypothesis explained the observed speed-accuracy trade-off, providing a framework within which aspects of technique can be identified and altered to improve performance.

The laws of bowling in cricket state 'a ball is fairly delivered in respect of the arm if, once the bowler's arm has reached the level of the shoulder in the delivery swing, the elbow joint is not straightened partially or completely from that point until the ball has left the hand'. Recently two prominent bowlers, under suspicion for transgressing this law, suggested that they are not 'throwing' but due to an elbow deformity are forced to bowl with a bent bowling arm. This study examined whether such bowlers can produce an additional contribution to wrist/ball release speed by internal rotation of the upper arm. The kinematics of a bowling arm were calculated using a simple two-link model (upper arm and forearm). Using reported internal rotation speeds of the upper arm from baseball and waterpolo, and bowling arm kinematics from cricket, the change in wrist speed was calculated as a function of effective arm length, and wrist distance from the internal rotation axis. A significant increase in wrist speed was noted. This suggests that bowlers who can maintain a fixed elbow flexion during delivery can produce distinctly greater wrist/ball speeds by using upper arm internal rotation.

Cricket is one of the world's most technical sports: batting, bowling and fielding constituting its major disciplines, each one differs in its performance objectives and skills. Although these obje...

Kinematic studies have shown that fast bowlers have run-up velocities, based on centre of mass velocity calculations, which are comparable to elite javelin throwers. In this study, 34 fast bowlers (22.3 +/- 3.7 years) of premier grade level and above were tested using a three-dimensional (3-D) motion analysis system (240 Hz). Bowlers were divided into four speed groups: slow-medium, medium, medium-fast, and fast. The mean centre of mass velocity at back foot contact (run-up speed) was 5.3 +/- 0.6 m/s. Centre of mass velocity at back foot contact was significantly faster in the fastest two bowling groups compared to the slow-medium bowling group. In addition, stepwise multiple regression analysis showed that the centre of mass deceleration over the delivery stride phase was the strongest predictor of ball speed in the faster bowling groups. In conclusion, centre of mass kinematics are an important determinant of ball speed generation in fast bowlers. In particular, bowlers able to coordinate their bowling action with periods of centre of mass deceleration may be more likely to generate high ball speed.

The classification of bowling actions in cricket is particularly important from an injury perspective. Research has consistently shown that bowlers with a mixed-action technique have an elevated risk of sustaining serious lumbar injury. In this study, 34 New Zealand bowlers (mean age 22.2±0.9 years) of premier competition standard and above were assessed using a three-dimensional motion analysis system (240 Hz). Data were analysed using three previous classification systems before classifying bowlers into the side-on, semi-open, front-on, and mixed-action types based on a modified set of angle threshold criteria and a more intuitive angle convention system. The majority of bowlers in the sample (64.7%) used the mixed action with high levels of shoulder counter-rotation. The strongest predictors of shoulder counter-rotation were shoulder alignment angle and pelvic–shoulder separation angle. The current results suggest that a large proportion of fast bowlers may be at a higher risk of lumbar injury...

Cricket fast bowlers have a high incidence of serious lumbar injuries, such as lesions in the pars interarticularis. Kinematic studies have shown that bowling actions with large shoulder counter-rotation are associated with significantly higher incidences of lumbar injury. However, in bowling, there has been no calculation of the spinal loads, which are the causal mechanisms of such injuries. In this study, 21 fast bowlers (22.4±3.9 years) of premier grade level and above were tested using a three-dimensional (3D) motion analysis system. The mean ball release speed was 31.9±2.8 m s−1 and ranged from 27.0 to 35.6 m s−1. Kinematics and kinetics were calculated for lumbar spine lateral bending, rotation, and flexion during the delivery and power phases of bowling. Power calculations were used to define the actuation of lumbar spine motion as either active or controlled. The actuation of the lumbar spine was complex, involving multiple sequences of active and controlled motion. In addition, lumbar spine loads were largest during the power phase when the ground reaction forces were highest. In conclusion, the dynamic loads and the cyclical nature of their application when the spine is positioned near its end range of motion may be significant factors of injury to this region. In addition, the lumbar spine in bowling has to vigorously flex, laterally bend and rotate simultaneously in a complex interdependent sequence of actuation patterns. Therefore, any technical change to reduce injury susceptibility needs to consider the mechanics of whole body coordination and timing.

Cricket bowling is traditionally thought to be a rigid-arm motion, allowing no elbow straightening during the delivery phase. Conversely, research has shown that a perfectly rigid arm through delivery is practically unattainable, which has led to rule changes over the past years. The current rule requires a bowler not to increase the elbow angle by more than 15 degrees, thus requiring a measurement to confirm legality in "suspect" bowlers. The aims of this study were to evaluate whether the current rule is maintained over a range of bowlers and bowling styles, and to ascertain whether other kinematics measures may better differentiate between legal and suspect bowling actions. Eighty-three bowlers of varying pace were analysed using reflective markers and a high-speed (240 Hz) eight-camera motion analysis system in a laboratory. The change in elbow segment angle (minimum angle between the arm and forearm), the change in elbow extension angle with respect to the flexion-extension axis of a joint coordinate system, and the elbow extension angular velocity at ball release were measured. We found that bowlers generally bowled within a change in elbow extension angle of 15.5 degrees. However, this limit was unable to differentiate groups of bowlers from those who were suspected of throwing in the past. Improved differentiation was attained using the elbow extension angular velocity at ball release. The elbow extension angular velocity at ball release may be conceptually more valid than the elbow extension angle in determining which bowlers use the velocity-contributing mechanisms of a throw. Also, a high value of elbow extension angular velocity at ball release may be related to the visual impression of throwing. Therefore, it is recommended that researchers and cricket legislators examine the feasibility of specifying a limit to the elbow extension angular velocity at ball release to determine bowling legality.

Cricket fast bowlers have a high incidence of serious lumbar injuries, such as lesions in the pars interarticularis. As lumbar loading is the causal mechanism of such injuries, the purpose of this study was to find relationships between lumbar spine kinetics, selected kinematic variables and the subsequent development of lumbar spine injury. At the beginning of the cricket season, the bowling techniques of 13 young fast bowlers (17.4 ± 1.9 years) from the Cricket New South Wales development squad were assessed using a three-dimensional motion analysis system (200 Hz). Using Kintrak software, kinematics and lumbar spine kinetics (forces and moments) were calculated about the L5/S1 joint during the arm acceleration phase. Towards the end of that season, each bowler underwent an MRI scan that took sagittal and axial sequences (T1 and T2) from T12 to S1. The largest kinetic values were lumbar compression forces and lumbar flexion moments. Maximum lumbar spine moments were associated with several kinematic variables such as front knee angle, pelvic and thoracic rotation at ball release and shoulder counter-rotation. There was an increased incidence of S1, L4 and L5 stress fractures and responses when shoulder counter-rotation exceeded 44°, lumbar compression force exceeded 8 time body weight (BW) and compression multiplied by flexion torque exceeded 20 BW2 m. This study suggests that lumbar spine forces and moments are dependent on a number of fundamental kinematic descriptors of bowling technique. By modifying the technique, bowlers may be able to reduce lumbar loads to reduce the risk of lumbar injury.

Fast bowling in cricket is an athletic motion requiring the coordination of multiple body segments in order to release a ball at high speed. The application of the kinetic link principle to bowling proposes that the optimal coordination of movement actuation follows a proximal to distal sequence, allowing the systematic and progressive transfer of angular momentum from the larger, heavier body segments to the smaller distal segments. An analysis of segmental kinetic energy potentially provides information on the order of segmental sequencing and the effectiveness of energy transfer between the segments throughout the kinetic link chain. However, there has been no calculation of segmental kinetic energy in cricket fast bowling. In this study, 34 fast bowlers (22.2 ± 3.9 years) of premier grade level and above were tested using a three-dimensional motion analysis system (240 Hz). Based on the range of measured balls (27.0 m s-1 to 35.6 m s-1), the sample was divided into four speed group categories: slow-medium, medium, medium-fast and fast. With exception of the fast group relative to medium-fast group, each faster group tended to have higher segmental kinetic energies. Although there were no clearly discernible sequencing differences between bowling speed groups, the temporal occurrences of peak segment kinetic energies showed that bowlers exhibited a general order of proximal to distal sequencing with the larger heavier proximal segments having the highest energy and activated first. In general, there is an approximate proximal to distal sequence in cricket bowling, which indicates that bowlers of varying speed levels first produce high kinetic energies in their trunk segments before circumducting the bowling arm during the acceleration phase.