Bibliography: p. 141-166.

Historically, cricketing literature has explored the disciplines of bowling and batting, with fielding receiving little attention until its importance was highlighted by the introduction of T20 matches. The novelty of this research lies in its clinically meaningful contribution to understanding shoulder injury aetiology in cricketers as overhead throwing athletes. The studies included in this thesis investigate the musculoskeletal profile of a cricketer’s shoulder, as well as the intrinsic factors associated with shoulder injury risk. Further, the influence of some of these risk factors on the cricketers’ overhead throwing biomechanics is explored and intend to improve the development of cricket-specific shoulder injury prevention programmes. An overview of the literature (Chapter 2) includes the epidemiology of shoulder injuries in cricketers; as well as a description of overhead throwing kinematics and the musculoskeletal adaptations associated with overhead throwing in cricket, compared to baseball, which has the greatest volume of throwing related studies. Based on previous outdated definitions of injury and not the current consensus definitions, shoulder injuries in cricket have been reported to occur infrequently. Various injury surveillance studies have identified time-loss shoulder injuries in cricketers, yet none have considered non-time-loss shoulder injuries. Although a limited number of studies have proposed potential intrinsic risk factors to shoulder injury in cricketers, no associations have been found. However, the cricketer’s shoulder is prone to injury due to the high forces generated while repeatedly throwing overhead during fielding. While overhead throwing biomechanics has been well investigated in baseball, minimal research exists for cricket. In addition, the understanding of throwing biomechanics in cricket has relied on two-dimensional motion analysis that is known to be insufficient for the analysis of rotational kinematics and kinetics. Elite (senior national and franchise) cricketers were recruited for this study. This study consisted of two parts. During the first part of the thesis demographic, training, competition and injury history data were obtained; and a shoulder-specific functional questionnaire and pre-season shoulder screening protocol were performed, prior to annual musculoskeletal screening. The incidence of all shoulder injuries were recorded throughout a six month cricket season. A profile of pertinent risk factors was assessed. The second part of the thesis evaluated throwing biomechanics of cricketers. Upper quarter, spinal, pelvic and hip kinematics, as well as shoulder and elbow kinetics were measured during the execution of overhead throwing from a stationary position, and with a run-up. This thesis includes three original papers and two experimental Chapters. The first paper (Chapter 3) documents the incidence of non-time-loss shoulder injuries in elite South African cricketers. Overall, the incidence of shoulder injury in cricketers during the 2016/2017 season was 18%, described as 5% time-loss and 13% non-time-loss injuries. Primary skill and fielding were negatively impacted in 100% and 80% of cricketers who sustained non-time-loss shoulder injuries, respectively. The entire cricket cohort recorded low scores on the shoulderspecific questionnaire, completed pre- and post-season, irrespective of injury history or injury sustained during the 2016/2017 season indicating a generalised reduction in the level of function in overhead activity. Paper 2 (Chapter 4) provides a description of the musculoskeletal profile of a cricketer’s shoulder which is atypical to the “thrower’s paradox” described in baseball. Specifically, cricketers present with a loss in total glenohumeral (GH) rotational range of motion (ROM), GH internal rotation deficit (GIRD) in the absence of external rotation gain (ERG); and global weakness of the rotator cuff and scapula stabilising muscles. Further, dominant shoulder supraspinatus tendon (SsT) thickness ≥5.85mm (sensitivity: 72%, specificity: 63%) and nondominant pectoralis minor length (PML) ≤12.85cm (sensitivity: 83%, specificity: 55%) predicted seasonal dominant shoulder injury (p< 0.05). From the findings indicated in Papers 1 and 2 (Chapters 3 and 4) it can be postulated that cricketers are generally a high-risk population for shoulder injury, amongst overhead throwing athletes, due to the lack of shoulder-specific musculoskeletal adaptation frequently observed in other overhead throwing populations. Paper 3 (Chapter 5) and experimental Chapters 6 and 7 investigate the kinematics and kinetics of overhead throwing from a stationary position, with a run-up and the consequence of GIRD in these two throwing approaches. A kinematic description of overhead throwing in cricket is provided and compared to baseball overhead pitching, in Paper 3 (Chapter 5). Maximum external rotation (MER) was regarded as the most critical point for potential shoulder injury in cricketers when throwing overhead from a stationary position. Further, a comparison between playing levels highlighted that amateur cricketers may display an increased risk for shoulder injury at MER as these cricketers were found to have decreased elbow flexion ROM in 2-14% of the throwing cycle (p=0.01), as well as greater shoulder (p=0.021) and elbow (p=0.043) compression and increased superior shoulder force (p=0.022) at MER, when compared to elite cricketers. Findings from experimental Chapter 6 indicate that when throwing with a run-up (dynamic) increased lumbo-pelvic (p=0.02) and hip flexion (p=0.01) occur sporadically in the throwing cycle, compared to throwing from a stationary position (static). In addition, increased shoulder compression (p=0.02) and posterior force (p=0.009) occur at MER, while reduced superior shoulder force (p=0.005) and elbow compression (p=0.03), superior (p=0.002) and medial (p=0.03) forces occur at ball release (BR), when throwing dynamically versus statically. These two Chapters highlight MER as the most critical point for potential shoulder injury in cricketers, which may further be attenuated by the absence of ERG, level of play and throwing from a stationary position while fielding. Experimental Chapter 7 investigated and highlights the potential correlations between GIRD, a frequently described risk factor for overhead athletes, and the other musculoskeletal variables measured, as well as overhead throwing biomechanics from a stationary and runup approach. Greater GIRD was associated with reduced passive hip external rotation ROM on the dominant side (p< 0.03), measured by inclinometer. In addition, increased GIRD was associated with reduced dominant hip abduction ROM during 0-23% of the throwing cycle (p=0.002), and superior shoulder force (p< 0.004) and elbow compression (p< 0.009), when throwing from a stationary position. Finally, greater GIRD was associated with increased posterior shoulder force at maximum internal rotation (MIR), when throwing from a stationary position (p< 0.013) and with a run-up (p< 0.03). These findings suggest that GIRD may negatively influence ball velocity specifically when cricketers attempt to throw overhead from a stationary position. Further, it is postulated that when throwing overhead (irrespective of approach) cricketers may overcome the mechanical insufficiency of GIRD by actively engaging the dominant hip internal rotators, to prematurely rotate the pelvis forward, in order to generate sufficient ball velocity. This may result in cricketers employing a throw across the body, which when repeatedly performed may cause hypertrophy of the dominant hip internal rotators, thereby reducing passive hip external rotation ROM. This biomechanical adaptation to GIRD may contribute to the cricketer’s predisposition for shoulder injury when throwing overhead, or may occur in an attempt to protect the shoulder against further injury. In conclusion, the inherent musculoskeletal profile of this elite cricketing cohort’s shoulder increases injury risk, particularly when throwing overhead. There is a need to investigate the influence of throwing volume, duration of season and player speciality on the musculoskeletal profile of the shoulder and concomitant injury in cricket. It is suggested that modifiable intrinsic factors found to be associated with shoulder injury and the performance of overhead throwing should be appropriately incorporated into injury prevention or pre-season conditioning programmes, to reduce the occurrence of injury. Further research should determine the efficacy of these programmes on shoulder injury prevention and throwing performance, in cricketers.

Background: Athletes training for peak performance have periods of systematic overload followed by recovery. The balance between overload and recovery is important to avoid unexpected fatigue or underperformance. The relationship between overload and recovery is unique for each athlete. Thus, programmes designed to monitor fitness and fatigue should consider the inter-athlete differences. Aim: The broad aim of the PhD thesis was to assess the relationships between various tools for monitoring fitness and fatigue in elite level athletes. Subjective and objective training/match demands, questionnaires to assess wellness and readiness-to-train as well as countermovement jump variables to assess neuromuscular performance were investigated within 4 inter-related studies. Methods: Four inter-related studies were designed to determine; 1) the validity and reliability of countermovement jump variables measured on a force plate in the laboratory; 2) the relationships between countermovement jump variables, responses to a wellness and readinessto-train questionnaire and exercise-induced fatigue in the laboratory; 3) the relationships between training load, responses to a wellness and readiness-to-train questionnaire and neuromuscular performance in elite level female field hockey athletes measured in a “realworld” situation, and 4) the relationships between these same variables for each athlete and whole team before, during and after international match play. Primary findings: The findings for each inter-related study were as follows; 1) Maximum force, rate of force development, jump height, flight time and time to maximum force, as measured on a force plate during a countermovement jump were valid and reliable. The typical error of measurement was defined for each variable. The validity and reliability were best in participants who had more strength training experience. In most cases the precision of the variables was sufficient to detect “small” changes. 2) Subjective measures (wellness questionnaire) were more sensitive to acute exercise-induced fatigue compared to objective measures of neuromuscular performance; 3) The relationship between variables differed between players. Multiple variables should be collected to better understand a player's subjective and objective fitness and fatigue status in response to subjective and objective measures of match and/or training demands; 4) Pre, intra and post-match related data should be collected to better understand individual player responses between matches. Variables such as jump height, rating of perceived exertion, total distance during the match, bodyload (a derived measure of the total external mechanical stress from accelerations, decelerations and change of direction) and subjective wellness should be considered when monitoring athlete training status. Conclusions: Firstly, there is no set standard battery of tools that can be used to monitor fitness and fatigue of athletes as the relationship between variables is not consistent between athletes. Variables such as jump height, rating of perceived exertion, total distance, bodyload and wellness responses should be considered in a monitoring system. Secondly, this thesis proposes the novel concept of “monitoring specificity”. This suggests that different tools, based on their responsiveness, should be used at an individual level. Thirdly, identifying which athletes are most sensitive to certain variables will reduce the “noise” within a team's monitoring system. This will enable better informed decisions to be made about the athlete's fitness/fatigue status.

Includes bibliographical references. / Background: The tackle in rugby union is a dynamic and high impact contact situation that occurs frequently during matches and exposes players to high risk of injury and muscle damage. The inability to tackle will result in opposition players gaining territory and possibly scoring points. Indeed, the ability to effectively engage in tackle contact has been associated with team success. While the risk of injury may always be present during these physical contests between the ball-carrier and tackler, coaching of proper techniques and skills may reduce the risk of injury, and at the same time improve performance. With that said, little is known about the knowledge, attitudes and behaviours of rugby union coaches towards coaching the tackle. Therefore the aim of this study was to assess coaches’ knowledge, attitudes and behaviours towards coaching the tackle. Methods: The top 8 rugby-playing schools (Premier A Division) in the Western Province Rugby Union participated in the study (representing 100% of the entire population of top-level junior schools in the region). A questionnaire was used to assess coaches’ knowledge, attitude and reported behaviour. Tackle training behaviour was also observed over a period of 4 weeks at the start of the season. Results: Sixty-two percent of coaches rated proper tackle technique to reduce the risk of injury as very important and 75% of coaches rated proper tackle technique as very important for improving performance. The tackle was practiced in 16% (n=15) of the total practice sessions (n=96). Coaches did not emphasise safety during the tackle sessions. Tackle training was over-reported by 75% (n=5) of coaches during the 4-week observational period. Discussion/Conclusion: Majority of coaches are aware of the high risk of injury associated with the tackle. Most coaches believe that tackle technique can improve tackle performance and safety during the tackle event. Coaches develop new 2 methods mostly through resources such as coaching colleagues and watching televised and live rugby matches. During the observed training period however, only 15 tackle training sessions were observed. It may be important to identify how much tackle training should occur during the pre-season and competition phase of the season to adequately prepare players for competition without increasing the risk of injury. The latest research on ways to reduce the risk of injury and improve performance in the tackle should also be disseminated through the appropriate channels that coaches are known to use. Tackle training guidelines should be based on scientific evidence, and these guidelines should outline how coaches need to design their training to meet their team requirements. Further research should identify which coaching behaviours can be used to effectively train tackle safety and tackle performance during training sessions. Keywords: Rugby union, tackling, coaching, injury prevention, attitude, knowledge, behaviour

Includes bibliographical references. / Professional rugby union is a contact sport with a high risk of injury. The Super Rugby competition is a particularly demanding 16-week Southern Hemisphere tournament. In this tournament, 15 teams compete and play international level matches every week, which may be associated with an even higher risk of injuries. The main objectives of this dissertation were 1) to review the epidemiology and risk factors of injuries in professional rugby union, with specific reference to the Super Rugby tournament (Part 1), and 2) to document the incidence and nature of time-loss injuries during the 2012 Super Rugby tournament (Part 2). Part 1: In this component of the dissertation, a comprehensive review of injuries during Super Rugby was undertaken. A search revealed only 3 studies that have been conducted during this competition. Therefore additional data were included from other studies on Rugby Union, where appropriate. Part 2: This component of the dissertation consists of a prospective cohort study that was conducted during the 2012 Super Rugby tournament, in which teams from Australia, New Zealand and South Africa participated. Participants consisted of 152 players from five South African teams. Team physicians collected daily injury data through a secure, webbased electronic platform. Data included the size of the squad, the type of day, main player position, whether it was a training or match injury, hours of play (training and matches), the time of the match injury, the mechanism of the injury, the main anatomical location of the injury, the specific anatomical structure of the injury, the type of injury, and the severity of the injury (days lost).

Background: The epidemiology and risk factors associated with medical complications, including life-threatening complications during distance running events has not been well described. The aims of this research were to document the incidence of medical complications (study 1), determine risk factors associated with medical complications (studies 2 and 3), and develop and apply a pre-race medical screening tool to determine the prevalence of chronic disease in race entrants, using a risk stratification model (study 4). Design: Prospective studies Setting: Two Oceans Marathon races (2008-2011) (studies 1-3) and race entrants (2012) Participants: Studies 1-3: 65 865 race starters; 21.1 km (n =39 511), 56 km runners (n=26 354). Study 4: 15 778 race entrants Methods: Study 1: In all 4 years, race day medical complications were recorded and subdivided by severity (serious life-threatening/death), organ system and final diagnosis. Studies 2 and 3: Independent risk factors associated with all medical complications, severity and organ system involvement were determined in 21.1 and 56km runners, using multivariate modeling. Study 4: A pre-race medical screening tool was developed, based on international pre-exercise medical screening guidelines, and administered to all race entrants (2012). The prevalence (%) of runners with four risk categories was determined. Results: The incidence (per 1000 race starters) of all and serious/life-threatening medical complications was 8.27 and 0.56 respectively (study 1). Risk factors associated with medical complications were less experience (56km), slower running pace (56 km) and older females (21.1 km) (studies 2 and 3). 16.8% runners were identified as those that should undergo medical evaluation for suspected cardiac disease with 3.4% reporting existing CVD (very high risk) and 13.4% reporting multiple CVD risk factors (high risk) (study 4). Conclusion: The incidence of all and serious/life-threatening medical complications in the 21.1km and 56km race is 1/121 and 1/1786 race starters respectively. Race experience, running pace and sex are risk factors for medical complications. 16.8% runners have underlying suspected cardiovascular disease. These data formed the basis for the implementation of a pre-race medical screening and risk stratification. The research lays the foundation for a future educational intervention programme to reduce the risk of medical complications in distance running and other endurance events.

Background Cycling is a popular recreational and competitive form of physical activity and method of transport. Cycling is broadly categorised as road cycling or mountain biking, and each form presents unique challenges and has different skill requirements. While cycling, in general, provides many benefits to both physical health and social behaviours, there are legitimate concerns about injuries related to both road and mountain cycling. Most of the available research presents the injury incidence in commuter or road cycling, with an apparent lack of evidence in mountain biking. The van Mechelen model of injury prevention outlines four stages in injury prevention research; the first stage investigates the extent of the injury and provides the basis on which the remaining stages depend. Based on the van Mechelen conceptual model, the broad aim of this thesis was to investigate acute injury epidemiology in mountain biking and the factors affecting bicycle control and falling. Investigations We performed a systematic review of the incidence of injury in mountain biking. Acute injury incidence ranged from 4% to 71% in cross-country mountain bike races. The causal indicators of bicycle control may include balance, agility and visual perception. In a pilot study, we developed novel tests to assess static bicycle balance and bicycle agility as measures of bicycle control. In the following study, we developed additional dynamic bicycle balance with four increasingly difficult levels. In this study, twenty-nine participants attended three days of repeated testing for reliability assessments of these tests. Participants also completed an outdoor downhill run. Performance in the balance tests were compared to performance in the outdoor downhill test to assess their ecological validity. All tests were assessed for reliability using typical error of measurement, standardised typical error, intraclass correlation coefficients, limits of agreement, effect sizes and repeated measures ANOVA's (with post hoc testing) analyses. The novel bicycle balance and agility were significantly associated with the performance in the outdoor downhill run (r=-0.51 to 0.78; p=0.01 to 0.0001). Cognitive and physical fatigue are factors that may contribute to loss of control of the bicycle. In our final study, we aimed to assess the effect of these factors on the performance in the novel tests. Rate of perceived exertion was significantly increased for all tests following physical fatigue (Cliff's d effect size= 0.27-0.40; p=0.001 to 0.037), but balance and agility performance were not affected. Cognitive fatigue had no effect on balance and agility performance. The fatigue induced in these protocols was insufficient to change performance in the bicycle-specific balance and agility tests. This indicates that either the fatigue protocols did not sufficiently replicate the fatigue experienced in mountain biking or that the tests are too blunt to be affected by the magnitude of fatigue in these protocols. Conclusion The overall incidence of injury in mountain biking is difficult to determine due to different injury definitions in the research. However, the available data clearly indicates an area of concern in sports and exercise medicine. We developed novel tests to assess the skill components of balance and agility on a mountain bike. The novel bicycle-specific tests are robust assessments of mountain biking performance and can be applied in clinical and research environments to determine bicycle control. Cognitive and physical fatigue did not affect performance on these novel tests. Based on the overall findings of our studies, we recommend that further research is conducted on the epidemiology of mountain biking injuries. The effect of fatigue on the novel tests needs to be investigated further using a combination of physical and cognitive fatigue.