THE EFFECT OF MODEL COMPLEXITY ON TRACKING CRICKET FAST BOWLERS USING INVERSE KINEMATICS IN OPENSIM

The purpose of this study was to investigate the effect of model complexity on the measurement of segmental kinematics. Three-dimensional marker coordinates from 13 cricket fast bowlers were used to drive an inverse kinematics routine in OpenSim using a 20-segment, whole-body model with the shoulder joint centres of rotation fixed within a rigid trunk segment. Adding shoulder joint translation to the model improved the fit of marker coordinates through the inverse kinematics routine and significantly changed joint angles throughout the body. Switching the rigid trunk for a model with anatomically appropriate levels of lumbar movement did not further improve the overall accuracy of marker coordinate reconstruction; however the shoulder extension angle was affected by approximately five degrees

MECHANICS OF REAR LEG MOTION IN CRICKET FAST BOWLING

The purpose of this study was to calculate the kinematics and kinetics of the rear leg drive in fast bowling, and then investigate whether any of these variables are associated ball release speed. Eighteen young fast bowlers (17.2 ±1.7 years) were recruited from the Cricket NSW development squad, and their bowling actions captured by a Cortex 2.0 motion analysis system. The data shows that rear leg drive primarily consisted of hip and knee motions in the flexion-extension plane, subject to a complex control strategy involving time-varying torques. The most prominent kinematic feature was rear knee extension velocity (r=0.55, p=0.019), which was moderately correlated with ball speed. However, more research is needed to evaluate the control of this variable, since none of the rear leg joint torques was correlated with rear knee extension velocity

LUMBAR KINEMATICS AND KINETICS OF YOUNG AUSTRALIAN FAST BOWLERS

Lower back injuries are a serious concern for cricket fast bowlers. As lumbar loading is the causal mechanism of such injuries, the purpose of this study was to find relationships between lumbar loads and selected kinematic variables. Thirteen young fast bowlers (17.4 ± 1.9 years) were tested with a 3-D motion analysis system (200 Hz). Kinematics and lumbar spine kinetics were calculated about the L5/S1 joint during the arm acceleration phase. The largest kinetic values were the lumbar axial 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. Modifying bowling kinematics may reduce lumbar loads and reduce the potential for lower back injuries

The identification of risk factors for ankle sprains sustained during netball participation

Objectives: Ankle sprains account for a large percentage of injuries sustained in netball. The identification of risk factors for ankle sprain is the preliminary action required to inform future prevention strategies. Design: Prospective study. Participants: Ninety-four netball players from club and inter-district teams. Methods: Preseason data were collected for; vertical jump height, perceived ankle instability, sprain history, arthrometry inversion-eversion angles, star excursion balance test reach distances, the number of foot lifts during unilateral stance and demi-pointe balance test results. Participants were followed for the duration of one netball season and ankle sprains were recorded. Results: Eleven sprains were recorded for eleven players using a time-loss definition of injury. Ankle sprains occurred at an incidence rate of 1.74/1000 h of netball exposure. One risk factor was identified to increase the odds of sustaining an ankle sprain during netball participation – a reach distance in the posterior-medial direction of the star excursion balance test of less than or equal to 77.5% of leg length (OR = 4.04, 95% CI = 1.00–16.35). Conclusions: The identified risk factor can be easily measured and should be considered for preseason injury risk profiling of netball players. Netball players may benefit from training programs aimed at improving single leg balance

An investigation of the reproducibility of a self-selected natural feet position when standing: Implications for the assessment of upright standing posture

Background Photogrammetry is often used to evaluate standing static postural alignment. Patients are often instructed to self-select a natural feet position but it's unclear whether this position can be consistently replicated across repeated assessments. Objective To determine whether people can replicate a self-selected natural feet position in upright standing across three sessions on different days. Design Between days test-retest reliability. Setting University laboratory. Methods Three variables – Base of Support (BoS), Foot Width (FW), Feet Opening Angle (FOA) – were measured from foot tracings of 150 participants (18–30 years) using established procedures. BoS data were assessed for systematic bias (Analysis of Variance), and absolute (Coefficient of Variation - CV%) and relative (Intraclass Correlation Coefficient - ICC) reliability. Results There was systematic bias in the BoS data across the three testing sessions. The CV% for the BoS data was 15.2%. The ICC (95% CI) for the BoS data was 0.84 (0.79–0.87). There were moderate-large correlations between the BoS and both FOA and FW respectively within each session. Conclusion If clinicians want to allow patients to use their self-selected natural feet position for repeated photogrammetric assessment of their static postural alignment it would be better to standardise the position of the feet, for example, by creating a tracing of a patient's self-selected natural feet position

Total, regional and unilateral body composition of professional English first-class cricket fast bowlers

There have been few reports of advanced body composition profiles of elite fast bowlers in the sport of cricket. Therefore, the aim of the current study was to determine total, regional and unilateral body composition characteristics of elite English first-class cricket fast bowlers in comparison with matched controls, using dual-energy X-ray absorptiometry (DXA). Twelve male fast bowlers and 12 age-matched, non-athletic controls received one total-body DXA scan. Anthropometric data were obtained as well as left and right regional (arms, legs and trunk) fat mass, lean mass and bone mineral content. Fast bowlers were significantly taller and heavier than controls (P<0.05). Relative to body mass, fast bowlers possessed greater lean mass in the trunk (80.9±3.7 vs. 76.7±5.9%; P=0.047) and bone mineral content in the trunk (2.9±0.3 vs. 2.6±0.3%; P=0.049) and legs (5.4±0.5 vs. 4.6±0.6%; P=0.003). In the arm region, fast bowlers demonstrated significantly greater unilateral differences in bone mineral content (10.6±6.6 vs. 4.5±3.9%; P=0.012). This study provides specific body composition values for elite-level fast bowlers and highlights the potential for muscle and bone imbalances that may be useful for conditioning professionals. Our findings also suggest beneficial adaptations in body composition and bone mass in fast bowlers compared with their non-athletic counterparts

Passive range of motion of the hips and shoulders and their relationship with ball spin rate in elite finger spin bowlers

Objectives: Investigate rotational passive range of motion of the hips and shoulders for elite finger spin bowlers and their relationship with spin rate. Design: Correlational. Methods: Spin rates and twelve rotational range of motion measurements for the hips and shoulders were collected for sixteen elite male finger spin bowlers. Side to side differences in the rotational range of motion measurements were assessed using paired t-tests. Stepwise linear regression and Pearson product moment correlations were used to identify which range of motion measurements were linked to spin rate. Results: Side to side differences were found with more external rotation (p = 0.039) and less internal rotation (p = 0.089) in the bowling shoulder, and more internal rotation in the front hip (p = 0.041). Total arc of rotation of the front hip was found to be the best predictor of spin rate (r = 0.552, p =  0.027), explaining 26% of the observed variance. Internal rotation of the rear hip (r = 0.466, p =  0.059) and the bowling shoulder (r = 0.476, p =  0.063) were also associated with spin rate. Conclusions: The technique and performance of elite finger spin bowlers may be limited by the passive range of motion of their hips and shoulders. The observed side to side differences may indicate that due to the repetitive nature of finger spin bowling adaptive changes in the rotational range of motion of the hip and shoulder occur

Ground reaction force, spinal kinematics and their relationship to lower back pain and injury in cricket fast bowling: A review

BACKGROUND: Fast bowlers display a high risk of lower back injury and pain. Studies report factors that may increase this risk, however exact mechanisms remain unclear. OBJECTIVE: To provide a contemporary analysis of literature, up to April 2016, regarding fast bowling, spinal kinematics, ground reaction force (GRF), lower back pain (LBP) and pathology. METHOD: Key terms including biomechanics, bowling, spine and injury were searched within MEDLINE, Google Scholar, SPORTDiscuss, Science Citation Index, OAIster, CINAHL, Academic Search Complete, Science Direct and Scopus. Following application of inclusion criteria, 56 studies (reduced from 140) were appraised for quality and pooled for further analysis. RESULTS: Twelve times greater risk of lumbar injury was reported in bowlers displaying excessive shoulder counter-rotation (SCR), however SCR is a surrogate measure which may not describe actual spinal movement. Little is known about LBP specifically. Weighted averages of 5.8 ± 1.3 times body weight (BW) vertically and 3.2 ± 1.1 BW horizontally were calculated for peak GRF during fast bowling. No quantitative synthesis of kinematic data was possible due to heterogeneity of reported results. CONCLUSIONS: Fast bowling is highly injurious especially with excessive SCR. Studies adopted similar methodologies, constrained to laboratory settings. Future studies should focus on methods to determine biomechanics during live play