Cricket

Elbow joint kinematics during cricket bowling using magneto-inertial sensors: A feasibility study

Magnetic and inertial measurement units (MIMUs) may provide an accessible, three-dimensional, in-field alternative to laboratory-restricted marker-based motion capture. Existing upper limb MIMU models have predominantly been validated with low-velocity motion and their suitability for use with sport-based movements remains relatively untested. We propose a MIMU system approach to enable the estimation of anatomically meaningful and participant-specific elbow kinematics with considerations for use with cricket bowling. A novel standardised elbow reference posture of 90 degrees flexion and 0 deg pronation, and functional definition of elbow joint axes of rotation calibrated the MIMU method model before it was validated across three experiments: (1) simple elbow rotations with a mechanical linkage; (2) low-velocity elbow rotations in human participants; and (3) low-medium velocity sport-based movements in human participants. The proposed MIMU method demonstrated high elbow kinematic measurement agreement when compared with a criterion measure across all three conditions. However, during experiment 3, sensor components neared their measurement capacity and the MIMU method elbow flexion measurement variability increased. We conclude that the proposed MIMU method can estimate anatomically referenced, participant-specific joint angles, however, the hardware specifications of currently available systems may limit application in high-velocity/acceleration situations, preventing the measurement of cricket bowling in-field for now.

A Review of the Evolution of Vision-Based Motion Analysis and the Integration of Advanced Computer Vision Methods Towards Developing a Markerless System

BACKGROUND

The study of human movement within sports biomechanics and rehabilitation settings has made considerable progress over recent decades. However, developing a motion analysis system that collects accurate kinematic data in a timely, unobtrusive and externally valid manner remains an open challenge.

MAIN BODY

This narrative review considers the evolution of methods for extracting kinematic information from images, observing how technology has progressed from laborious manual approaches to optoelectronic marker-based systems. The motion analysis systems which are currently most widely used in sports biomechanics and rehabilitation do not allow kinematic data to be collected automatically without the attachment of markers, controlled conditions and/or extensive processing times. These limitations can obstruct the routine use of motion capture in normal training or rehabilitation environments, and there is a clear desire for the development of automatic markerless systems. Such technology is emerging, often driven by the needs of the entertainment industry, and utilising many of the latest trends in computer vision and machine learning. However, the accuracy and practicality of these systems has yet to be fully scrutinised, meaning such markerless systems are not currently in widespread use within biomechanics.

CONCLUSIONS

This review aims to introduce the key state-of-the-art in markerless motion capture research from computer vision that is likely to have a future impact in biomechanics, while considering the challenges with accuracy and robustness that are yet to be addressed.

Illegal bowling actions contribute to performance in cricket finger-spin bowlers

With advances in technology, scientists are now able to more accurately measure elbow displacement changes during the cricket bowling action. This has led to the realization that the majority of bowlers undergo some degree of elbow extension during the forward swing phase of bowling. Consequently, the International Cricket Council were obliged to revise the once zero tolerance for elbow extension threshold to a 15° range. However, it is still not understood if bowling with >15° of elbow extension aids performance or alters other kinematic movements. The purpose of this study was to compare performance and technique measures between legal and illegal finger-spin bowlers. Data were collected from 48 pathway and elite bowlers using a 22-camera motion analysis system. Results indicated that the ball velocity and revolutions at ball release of pathway bowlers with illegal actions showed no significant difference and were similar to elite legal bowlers. Technique differences were also identified, with illegal bowlers being more front-on, forcing a reliance on increased elbow flexion and supination to impart effective ball kinematics at ball release. The performance benefit of greater ball velocity and revolutions is obtained when finger-spin bowlers deliver the ball with more than the allowable 15° of elbow extension, thus reinforcing the validity of the current bowling laws. To counteract bowling with an illegal action, it is recommended that a more side-on technique at back foot impact and rotating the trunk through to the point of ball release will assist bowlers in reducing undesirable elbow extension levels.

Lumbopelvic muscle activation patterns in adolescent fast bowlers

INTRODUCTION

Adolescent fast bowlers are prone to sustaining lumbar injuries. Numerous components have been identified as contributing factors; however, there is limited empirical evidence outlining how the muscles of the lumbopelvic region, which play a vital role in stabilising the spine, function during the bowling action and the influence of such activation on injuries in the fast bowler.

METHODS

Surface electromyography was utilised to measure the function of the lumbar erector spinae, lumbar multifidus, gluteus medius and gluteus maximus muscles bilaterally during the fast bowling action in a group of 35 cricket fast bowlers aged 12-16 years.

RESULTS

Two prominent periods of activation occurred in each of the muscles examined. The period of greatest mean activation in the erector spinae and multifidus occurred near back foot contact (BFC) and within the post-ball-release (BR) phase. The period of greatest mean activation for the gluteus medius and gluteus maximus occurred during phases of ipsilateral foot contact.

DISCUSSION

The greatest periods of muscle activation in the paraspinal and gluteal muscles occurred at times where vertical forces were high such as BFC, and in the phases near BR where substantial shear forces are present.

CONCLUSION

The posterior muscles within the lumbopelvic region appear to play a prominent role during the bowling action, specifically when compressive and shear forces are high. Further research is required to substantiate these findings and establish the role of the lumbopelvic muscles in the aetiology of lumbar injury in the cricket fast bowler.

The effect of elbow hyperextension on ball speed in cricket fast bowling

This study investigates how elbow hyperextension affects ball release speed in fast bowling. A two-segment planar computer simulation model comprising an upper arm and forearm + hand was customised to an elite fast bowler. A constant torque was applied at the shoulder and elbow hyperextension was represented using a damped linear torsional spring at the elbow. The magnitude of the constant shoulder torque and the torsional spring parameters were determined by concurrently matching three performances. Close agreement was found between the simulations and the performances with an average difference of 3.8%. The simulation model with these parameter values was then evaluated using one additional performance. Optimising ball speed by varying the torsional spring parameters found that elbow hyperextension increased ball release speed. Perturbing the elbow torsional spring stiffness indicated that the increase in ball release speed was governed by the magnitude of peak elbow hyperextension and the amount that the elbow recoils back towards a straight arm after reaching peak elbow hyperextension. This finding provides a clear understanding that a bowler who hyperextends at the elbow and recoils optimally will have an increase in ball speed compared to a similar bowler who cannot hyperextend. A fast bowler with 20° of elbow hyperextension and an optimal level of recoil will have increased ball speeds of around 5% over a bowler without hyperextension.

SIGNIFICANCE OF THE ELECTROMYOGRAPHIC ANALYSIS OF THE UPPER LIMB MUSCLES OF CRICKET BOWLERS: RECOMMENDATIONS FROM STUDIES OF OVERHEAD-THROWING ATHLETES

The purpose of this study was twofold: (i) to review the existing literature on electromyographic (EMG) analysis of the upper limb muscles of present overhead-throwing (OT) athletes during throwing and of cricket bowlers (CBs) during cricket bowling (CB) and, (ii) to discuss the importance of and generate recommendations for the EMG assessment of the muscle activity of CBs with respect to previous studies of OT athletes. A literature search of the PubMed, Scopus and Google Scholar electronic databases was performed to identify relevant articles published up to December 2012. This search was performed to evaluate the following areas, (i) what are the upper limb muscles that should be evaluated during OT sports and cricket bowling? (ii) what types of EMG methodologies have been used? (iii) what are the anthropometric, performance and physical functional variables that are usually selected? and (iv) what recommendations can be made for the assessment of the muscle activity of CBs? The search identifies 32 publications on OT athletes and 4 on CBs. The results note the following conclusions: (i) there are relatively few CB-related papers that utilize EMG, particularly for the assessment of muscle activity and coordination, (ii) a total of 22 upper limb muscles were investigated using EMG (from both criteria), (iii) surface electrodes are used more frequently than needle electrodes, (iv) most of the article normalized and analyzed the EMG amplitudes than the frequency, and the data was more often analyzed through a descriptive statistical analysis and (v) the majority of the studies analyzed the right limb of physically normal (uninjured) male's both the amateur and professional athletes that were 20 to 29 years of age. Finally, the published evidence on CBs is inadequate to validate a sound recommendation for the assessment of the muscles of CBs using EMG. However, the studies on OT athletes do provide guidelines that can be used to analyze CBs. The overall conclusion of this review show that, further studies are needed to evaluate the efficacy of EMG for the assessment of the upper limb muscle of CBs to ultimately identify and prevent injury which is still a matter of discussion in the sports medicine community.