Exploring the aetiology of high burden lower limb injuries in male professional rugby union players

Abstract The lower limb is the most frequently injured location in Rugby Union, resulting in significant injury burden to professional teams. In order to inform risk mitigation strategies, investigation of the aetiology of high burden lower limb injuries is required. However, sports injury aetiology is a complex problem that is dependent on a multitude of causal factors. The aim of the thesis was to advance knowledge of high burden knee ligament and hamstring injury aetiology in male professional rugby union players, by prospectively exploring the association between injury and selected intrinsic and extrinsic variables. The first experimental study of the thesis (Chapter Three) illustrates that over a period of seven playing seasons, injuries to the lower limb placed the highest burden on the rugby team participating in the research project, compared to the upper limbs, trunk, head and neck. Of these injuries, the locations resulting in highest injury burden were to the knee ligaments and the hamstrings. Specifically, injuries to the anterior cruciate ligament (ACL) sustained during contact events were infrequent but resulted in the highest severity. Injuries to the medial collateral ligament (MCL) sustained during tackle events and rucking placed a high injury burden due to a high incidence rate combined with moderate magnitudes of injury severity. Finally, biceps femoris strain sustained during running was the most frequently occurring injury. The findings of the study provided a focus for the subsequent experimental chapters. Chapter Five demonstrates that isokinetic measures of hamstrings and quadriceps strength have poor predictive value in relation to hamstring strains (the highest AUC score being 0.57), despite being associated with an increased odds of sustaining semimembranosus and semitendinosus strains. Isokinetic strength variables were not associated with sustaining biceps femoris strains. Previous injury to the hamstrings was observed to be associated with an increased odds of subsequent hamstring injury when all muscles were pooled. Previous injury to either the MCL or lateral ankle ligaments was associated with an increased risk of biceps femoris injury and medial hamstring injury. This investigation also identified that chronic exposure of high magnitudes was associated with an increased risk of hamstring injuries sustained during running, specifically exposure to high-speed running over 14 and 21 days prior to the week in which the injury was sustained. Chapter 6 examined a variety of variables which were theoretically associated with contact ACL and MCL injury aetiology. The influence of previous injury history was examined in relation to contact MCL and ACL injury aetiology. Previous knee ligament injury not associated with an increased risk of sustaining a subsequent knee ligament injury during a contact event. However, previous hamstring and triceps surae muscle strains were associated with an increased risk of injury. Isokinetic assessment of both hamstring and quadriceps strength exhibited poor predictive ability in relation to contact knee ligament injury (highest AUC = 0.57). Chapter 6 also examined contact MCL and ACL injury aetiology in relation to lower limb biomechanics during a single-leg drop jump task. Both larger magnitudes of external knee abduction moment and hip adduction moment 50 ms post ground contact were associated with an increased risk of injury. The study highlighted the importance of modelling injury as a rare event in relation to analysis involving player workloads. A minority oversampling algorithm was used to mitigate the negative effects of class imbalance within the player-workloads data sets. Exposure to tackle events during a match was not related to sustaining an MCL or ACL injury from a tackle. When tackle and ruck exposure were combined, increased exposure (during 7 and 14 days preceding the injury) was associated with a decrease in the odds of sustaining a contact MCL or ACL injury where the inciting event involved a tackle or a ruck. Exposure to on-pitch physical activity (PlayerLoadTM) in relation to contact MCL and ACL was also explored. Acute increases in PlayerLoadTM (3-day EWMA and 7-day EWMA) were associated with an increased odds of sustaining MCL injury and ACL injury. Increased magnitudes of chronic PlayerLoadTM exposure during the previous 7-days with a 3-day lag as well as the previous 14-days were both associated with an increased odds of MCL as well as pooled MCL and ACL injury. In summary, the thesis explores the lower limb injuries which place a high burden on male professional rugby players in addition to a selection of variables that are associated with their aetiology. The injuries that placed the highest burden were knee ligament injuries (MCL and ACL) sustained during contact as well as hamstring strains. The experimental chapters reinforce the importance of previous injury history in relation to injury aetiology, with previous injury to the proximal and distal tissues of the injured area increasing subsequent injury risk, suggesting that a more universal approach to rehabilitation may be required. The findings also demonstrate that isokinetic assessment of hamstring and quadriceps strength exhibits poor classification performance in relation to hamstring, MCL and ACL injury and should not be used to infer the subsequent risk of these injuries. In contrast, joint moments occurring at the early stages of ground contact during a single-leg drop-jump task are better at classifying knee ligament injury suggesting more dynamic tasks are required when investigating sports injury aetiology. Finally, the thesis explores the influence of player workloads in relation to injury aetiology, and highlights that the differences in this relationship depending on the injured tissue type as well as the data collection methodology. The studies within the thesis are some of the first to be conducted within a rugby union setting, with this in mind, the work within the thesis provides a conduit between epidemiological and mechanistic studies in addition to providing practical applications for men’s’ professional rugby teams

A study of the immunity of FM discriminators to 2 pi frequency impulses

Frequency impulse response of selected FM discriminator

Damage and repair classification in reinforced concrete beams using frequency domain data

This research aims at developing a new vibration-based damage classification technique that can efficiently be applied to a real-time large data. Statistical pattern recognition paradigm is relevant to perform a reliable site-location damage diagnosis system. By adopting such paradigm, the finite element and other inverse models with their intensive computations, corrections and inherent inaccuracies can be avoided. In this research, a two-stage combination between principal component analysis and Karhunen-Loéve transformation (also known as canonical correlation analysis) was proposed as a statistical-based damage classification technique. Vibration measurements from frequency domain were tested as possible damage-sensitive features. The performance of the proposed system was tested and verified on real vibration measurements collected from five laboratory-scale reinforced concrete beams modelled with various ranges of defects. The results of the system helped in distinguishing between normal and damaged patterns in structural vibration data. Most importantly, the system further dissected reasonably each main damage group into subgroups according to their severity of damage. Its efficiency was conclusively proved on data from both frequency response functions and response-only functions. The outcomes of this two-stage system showed a realistic detection and classification and outperform results from the principal component analysis-only. The success of this classification model is substantially tenable because the observed clusters come from well-controlled and known state conditions

Pragmatic Trellis Coded Modulation: A Simulation Using 24-Sector Quantized 8-PSK

Trellis Coded Modulation (TCM)[2,3,4], combines convolutional encoding with PSK or QAM signalling to provide spectrally efficient communication with forward error correction. Pragmatic TCM[1], uses the industry standard, 64-state, binary convolutional code. This paper presents a simulation of a pragmatic TCM system for 8-PSK. This system associates each sector of a quantized phase receiver[9] with a pair of weights to be used as soft decision inputs of the Viterbi decoder. This system approaches 3dB of coding gain at bit error rates of 10-5 and less

Discrete Analysis of a Composite Video Signal

In this paper the problem of representing the composite video signal for monochromatic T. V. transmission is examined and a method for computing the required spectral bandwidth is devised suitable for computer applications. The results obtained numerically are compared to measured results and to analytical solutions for a determinate signal for special cases. Comparison is made with some maximum horizontal resolution methods with a resulting decrease in bandwidth requirements for most applications

Stochastic method for in-situ damage analysis

Based on the physics of stochastic processes we present a new approach for structural health monitoring. We show that the new method allows for an in-situ analysis of the elastic features of a mechanical structure even for realistic excitations with correlated noise as it appears in real-world situations. In particular an experimental set-up of undamaged and damaged beam structures was exposed to a noisy excitation under turbulent wind conditions. The method of reconstructing stochastic equations from measured data has been extended to realistic noisy excitations like those given here. In our analysis the deterministic part is separated from the stochastic dynamics of the system and we show that the slope of the deterministic part, which is linked to mechanical features of the material, changes sensitively with increasing damage. The results are more significant than corresponding changes in eigenfrequencies, as commonly used for structural health monitoring.Comment: This paper is accepted by European Physical Journal B on November 2. 2012. 5 pages, 5 figures, 1 tabl

Stormwater harvesting: Improving water security in South Africa’s urban areas

The drought experienced in South Africa in 2016 – one of the worst in decades – has left many urbanised parts of the country with limited access to water, and food production has been affected. If a future water crisis is to be averted, the country needs to conserve current water supplies, reduce its reliance on conventional surface water schemes, and seek alternative sources of water supply. Within urban areas, municipalities must find ways to adapt to, and mitigate the threats from, water insecurity resulting from, inter alia, droughts, climate change and increasing water demand driven by population growth and rising standards of living. Stormwater harvesting (SWH) is one possible alternative water resource that could supplement traditional urban water supplies, as well as simultaneously offer a range of social and environmental benefits. We set out three position statements relating to how SWH can: improve water security and increase resilience to climate change in urban areas; prevent frequent flooding; and provide additional benefits to society. We also identify priority research areas for the future in order to target and support the appropriate uptake of SWH in South Africa, including testing the viability of SWH through the use of real-time control and managed aquifer recharge

Force and acceleration characteristics of military foot drill: implications for injury risk in recruits

Background: Foot drill involving marching and drill manoeuvres is conducted regularly during basic military recruit training. Characterising the biomechanical loading of foot drill will improve our understanding of the contributory factors to lower limb overuse injuries in recruits. Aim: Quantify and compare forces, loading rates and accelerations of British Army foot drill, within and between trained and untrained personnel. Methods: 24 trained soldiers (12 men and 12 women; TRAINED) and 12 civilian men (UNTRAINED) performed marching and five drill manoeuvres on force platforms; motion capture recorded tibial position. Peak vertical impact force (PF), peak vertical loading rate (PLR), expressed as multiples of body weight (BW) and peak tibial impact acceleration (PTA) were recorded. Results: Drill manoeuvre PF, PLR and PTA were similar, but higher in TRAINED men (PF, PLR: p<0.01; PTA: p<0.05). Peak values in TRAINED men were shown for the halt (mean (SD); PF: 6.5 (1.5) BW; PLR: 983 (333) BW/s PTA; PTA: 207 (57) m/s2) and left turn (PF: 6.6 (1.7) BW; PLR: 928 (300) BW/s; 184 (62) m/s2). Marching PF, PLR, PTA were similar between groups and lower than all drill manoeuvres (PF: 1.1–1.3 BW; PLR: 42–70 BW/s; p<0.01; PTA: 23–38 m/s2; p<0.05). Conclusions: Army foot drill generates higher forces, loading rates and accelerations than activities such as running and load carriage, while marching is comparable to moderate running (10.8 km/h). The large biomechanical loading of foot drill may contribute to the high rate of overuse injuries during initial military training, and strategies to regulate/reduce this loading should be explored

Dietary Plant Sterol Esters Must Be Hydrolyzed to Reduce Intestinal Cholesterol Absorption in Hamsters

Background: Elevated concentrations of LDL cholesterol are associated with the development of atherosclerosis and therefore are considered an important target for intervention to prevent cardiovascular diseases. The inhibition of cholesterol absorption in the small intestine is an attractive approach to lowering plasma cholesterol, one that is addressed by drug therapy as well as dietary supplementation with plant sterols and plant sterol esters (PSEs). Objective: This study was conducted to test the hypothesis that the cholesterol-lowering effects of PSE require hydrolysis to free sterols (FSs). Methods: Male Syrian hamsters were fed atherogenic diets (AIN-93M purified diet containing 0.12% cholesterol and 8% coconut oil) to which one of the following was added: no PSEs or ethers (control), 5% sterol stearate esters, 5% sterol palmitate esters (PEs), 5% sterol oleate esters (OEs), 5% sterol stearate ethers (STs; to mimic nonhydrolyzable PSE), or 3% FSs plus 2% sunflower oil. The treatments effectively created a spectrum of PSE hydrolysis across which cholesterol metabolism could be compared. Metabolic measurements included cholesterol absorption, plasma and liver lipid concentration, and fecal neutral sterol and bile acid excretion. Results: The STs and the PEs and SEs were poorly hydrolyzed (1.69–4.12%). In contrast,OEs were 88.3% hydrolyzed. The percent hydrolysis was negatively correlated with cholesterol absorption (r=20.85; P \u3c 0.0001) and positively correlated with fecal cholesterol excretion (r = 0.92; P \u3c 0.0001), suggesting that PSE hydrolysis plays a central role in the cholesterol-lowering properties of PSE. Conclusions: Our data on hamsters suggest that PSE hydrolysis and the presence of FSs is necessary to induce an optimum cholesterol-lowering effect and that poorly hydrolyzed PSEs may lower cholesterol through an alternative mechanism than that of competition with cholesterol for micelle incorporation

Pragmatic Trellis Coded Modulation: A Hardware Implementation Using 24-sector 8-PSK

Trellis Coded Modulation (TCM)[2,3], combines convolutional encoding with PSK or QAM signalling to provide spectrally efficient communication with forward error correction. Pragmatic TCM[4], uses the industry standard, 64-state, binary convolutional code. This paper presents a hardware implementation of a pragmatic TCM system for 8-PSK. This system associates each sector of a quantized phase receiver[7] with a pair of weights to be used as soft decision inputs of the Viterbi decoder. This system approaches 3dB of coding gain at bit error rates of 10-5 and less