Obstructive sleep apnoea (OSA) is a common chronic condition characterised by repetitive nocturnal upper airway collapse that evokes intermittent hypoxia (IH). Although animal research has demonstrated a causal relationship between IH and cardiovascular disease there is a relative paucity of human research. Using a variety of different models of OSA we investigated the effects of IH on respiratory control and oxidative stress. In addition, we attempted to use Doppler ultrasound to investigate the effects of hypoxic airway occlusions on the pulmonary circulation but concluded that it is not a feasible alternative to invasive catheterisation. In a number of studies we showed that the expression of respiratory plasticity following IH is only evident when arterial levels of CO\(_2\) are raised above normal levels. Furthermore, in stark contrast to previous findings in animals, exposure to acute continuous hypoxia also evokes respiratory plasticity in humans. In addition, we showed that combined postprandial hyperglycaemia and hyperlipidaemia augments the degree of oxidative stress during IH. Finally, we demonstrated that IH accentuates the magnitude of postprandial hyperglycaemia. These studies demonstrate the complexity of respiratory control in humans and they highlight significant species differences. Furthermore, they highlight a fascinating synergy between IH and the postprandial state.

Glucose transporter 4 (GLUT4) in skeletal muscle plays a vital role in the maintenance of glucose homeostasis. Chapter 2 of this thesis develops an immunofluorescence microscopy method to generate novel information in human skeletal muscle on the effect of physiological stimuli on GLUT4 localisation, translocation to the plasma membrane and total protein content. Chapter 3 shows that training-induced increases in total GLUT4 protein content are driven by increases in the number of large and size of smaller intracellular GLUT4 storage clusters in human skeletal muscle. In chapter 4 the method successfully demonstrates GLUT4 translocation 30 min following glucose ingestion and 30 min after the start of moderate intensity cycling exercise in humans. GLUT4 translocation after glucose ingestion is transient and modest in comparison to the exercise response. Chapters 5 and 6 report no changes in GLUT4 translocation following an 80 min hyperinsulinaemic-isoglycaemic clamp in rats and a 2 h hyperglycaemic clamp in humans despite elevated rates of whole body glucose disposal in both experiments. This immunofluorescence method will be a valuable analytical tool in future studies investigating the mechanisms behind changes in muscle glucose uptake in response to obesity, age-related chronic diseases and therapeutic interventions including diet and exercise.

Focal adhesion kinase (FAK) and paxillin are proteins implicated in the mechanisms that link chronic alterations in mechanical force within skeletal muscle and its microvasculature to the functional adaptation seen with changes in physical activity. This thesis developed novel immunofluorescence microscopy methods to visualise and measure FAK and paxillin responses in human skeletal muscle and its microvasculature. Chapter 2 reveals high FAK protein content in the (sub)sarcolemma of skeletal muscle fibres and within the microvascular endothelial and vascular smooth muscle cell layers. Chapter 3 demonstrates that FAK protein content is increased at (sub)sarcolemmal and sarcoplasmic regions of skeletal muscle fibres and within the microvascular endothelium following 12 weeks resistance-type exercise training in elderly individuals. Chapter 4 shows that FAK and paxillin colocalise at the (sub)sarcolemma of skeletal muscle fibres and within the microvasculature. Chapter 5 demonstrates that FAK and paxillin are increased at the (sub)sarcolemma and within the microvascular endothelium following 6 weeks endurance- and resistance-type exercise training in young previously sedentary individuals. The novel data generated in this thesis, in combination with recent literature findings, support the hypothesis that FAK and paxillin play an important role in upstream mechanotransduction signals that control skeletal muscle fibre hypertrophy, mitochondrial biogenesis, insulin sensitivity, microvascular function and angiogenesis.

Perceived exertional dyspnoea is reported to be the most common symptom among physically active individuals of all abilities and ages and/or performance in high level athletes, potentially impacting on performance and limiting enjoyment of sporting activities. Identifying the causes of the perceived symptoms requires careful assessment with a wide range of factors potentially contributing to the reported respiratory issues. The purpose of this thesis was to investigate different assessment approaches in the identification of breathing dysfunction in exercising adults. Elite swimming and boxing require athletes to achieve relatively high minute ventilation. In Chapter 4 (Study 1 of this thesis), thirty-eight elite boxers and 44 elite swimmers completed a thorough respiratory assessment that revealed a nine-fold greater prevalence of exercise-induced bronchoconstriction in swimmers when compared with boxers. These results suggested that the combination of a sustained high ventilation and provocative training environment may impact the susceptibility of athletes to this condition. Dysfunctional breathing may mimic and/or co-exist with exercise-induced bronchoconstriction. The use of specific questionnaires may improve the identification of this condition in athletes. In Chapter 5 (Study 2 of this thesis), 9% of the 428 healthy, physically active young adults who completed the Nijmegen Questionnaire had a score ≥ 23, suggestive of a dysfunctional breathing status. A separate cohort of 104 athletes underwent an indirect bronchoprovocation challenge and completed the Nijmegen questionnaire. The sensitivity, specificity, positive and negative predicted values suggested that the Nijmegen score was a poor predictor of a positive bronchoprovocation challenge in athletes and therefore is not suitable to detect dysfunctional breathing in athletes. The posture an athlete holds during exercise may alter breathing pattern and increase reported exercise induced respiratory symptoms. In order to investigate whether respiratory parameters are affected by different postural positions, in Chapter 6 (Study 3 of this thesis), 15 healthy male athletes performed a 10-minute, high intensity cycling test with normal shoulder position and with hunched shoulders. Results of this study showed that cycling with hunched shoulders at high intensities over a prolonged period leads to an increase in perceived dyspnoea and suggested that posture may contribute to reports of respiratory symptoms during exercise in the absence of cardio-pulmonary disease. With the aim of investigating the effect of different postural positions on the ventilatory excursion, in Chapter 7 (Study 4 of this thesis), 15 healthy male athletes performed baseline spirometric measurements and 10-minutes cycling challenges with normal shoulder position and with hunched shoulders, while undergoing simultaneous data collection with optoelectronic plethysmography. The findings of this study suggested that respiratory excursion and lung volume compartmentalisation at both rest and during high intensity exercise are affected by the position of the shoulders. In conclusion, athletes who train and compete in provocative environments at a sustained high ventilation have an increased susceptibility to airway dysfunction. No existing questionnaire is sensitive enough to identify dysfunctional breathing and differentiate it from other respiratory conditions, such as exercise-induced bronchoconstriction. Exercising for a prolonged period at high intensities with hunched shoulders triggers increased abdominal contribution to vital capacity and a subsequent increase in perception of breathing sensation without a significant effect on physiological markers of respiratory function. Further investigations should be undertaken in order to develop a new questionnaire that is more suitable for an athletic population and has higher accuracy in identifying symptoms associated with exercise induced breathing impairment. Precise detection of distortions between compartmental contributions in exercising individuals may play an important role in the differential diagnosis of dysfunctional breathing.

Mega-events such as the Olympics or Commonwealth Games are truly global events. Yet, the way in which these are utilised as a form of events led regeneration, gives these an increasingly local dimension; not only are Games taking place amidst the existing urban setting, but so too are their associate exceptional security features. Mega-events can also be considered representative of a new (in)security situation in which experts have been reactivated to operate on behalf of citizens; associations of invisible and omnipresent risks such as terrorism, have given executive authority to state agencies to define risks and develop responses, a situation which contradicts the last decades drive towards more community focused policing and empowerment. The cumulative and contradictory situation is that as global risks and security have become more embedded at the local level, there is an increasing of social distance between security expert and lay citizens. In short, local residents who encounter security within the context of their everyday environment are stripped of any contextual basis on which to understand associated risks and make sense of the attentive security measures. This situation places a greater emphasis on how risk and security is symbolically 'communicated' between experts and citizens, and how aspects of reassurance and deterrence are balanced amidst this backdrop. Existing literature in mega-events has tended to focus on security in a 'wide and shallow' sense: 'wide' in that they outline a whole range of security features and governance arrangements, but 'shallow' in the way that they do not take into account how these features are perceived at a deeper, local level. In this way, there is no real legacy to the security legacies. This thesis aims to address this issue by drawing on Glasgow's hosting of the 2014 Commonwealth Games. Qualitative interviews were used to gain the perspectives of both security experts from key stakeholder organisations responsible for delivering a safe and secure Games, and lay citizen’s perceptions and experiences of these arrangements. Using a semiotic theoretical lens, which includes key concepts from the work of Giddens, Baudrillard, Eco and Goffman, the analysis considers 1) How particular security related narratives are 'framed' by experts during the mega-event and how these were understood by residents in relation to local contexts, biographies and experiences. 2) The totalising and globalising claims of late modernity and mediated forms of risk are identified in relation to local understandings of place. In particular, why it is that certain events or places, legitimise the use of exceptional security and continue to licence executive state authority. 3) The sending and receiving of different forms of security as 'control signals' is analysed in relation to how overt displays of security are experienced; how they influence one’s position of reassurance, safety and ontological (in)security, and how they may enhance or defray trust in the institutions responsible for providing security. It is discovered that instances of miscommunication between state and citizen are rife, a situation exacerbated by the social distance created through existing governance arrangements and an overreliance on symbolic security. The thesis concludes by arguing that the governance of security at mega-events is not the best way of doing things and that the appropriation of issues of risk and security by experts creates new sources of insecurity among citizens. It calls for the enlisting of communities into the governance of security as a way of overcoming such limitations.

The aims of this thesis were to examine the relationships between relative age, maturity status, and physical phenotypes on the selection, playing position allocation, and development tempo of a broad sample of elite youth soccer players’ that best represents UK development programs governed by the Elite Player Performance Plan (EPPP). The first research study (Chapter 4) aimed to establish the short-term reliability (STR) and smallest worthwhile changes (SWC) for a battery of field tests commonly used to assess elite youth soccer players’ physical and somatic phenotypes. On two occasions, the within-practitioner STR of three anthropometric measures (stature, seated height and body-mass) were assessed to estimate age at peak height velocity (APHV). In addition, within-player STR of the Multi-Stage Fitness Test (MSFT), 10 and 20 m sprints were assessed using 45 elite youth soccer players (age: 13.5 ± 1.5 years; body-mass: 49.2 ± 10.3 kg; stature: 177.7 ± 6.4 cm). In addition, within-player STR was established for T-Test and counter-movement jump (CMJ) performance using 21 senior amateur soccer players (age: 24 ± 5.3 years; body-mass: 84.3 ± 7.1 kg; stature: 177.7 ± 6.4 cm). The within-practitioner STR (coefficient of variance [CV], (95% confidence interval [CI])) and SWC were established for anthropometric measures (stature: CV = 0.4 % [CI = 0.3 to 0.5 %], SWC = 2.3 cm; seated height: CV = 1.1 % [0.9 to 1.4 %], SWC = 1.1 cm; body-mass: CV = 0.7 % [0.6 to 0.9 %], SWC = 2.3 kg) and APHV (CV = 0.8 % [0.7 to 1.0 %], SWC 0.1 year) respectively. Within-player physical fitness reliability and SWC were also established for CMJ (CV = 5.9 % [4.6 to 9.0 %], SWC = 0.6 cm), T-Test (CV = 1.7 % [1.3 to 2.4 %], SWC = 0.08 s), 10 m sprint (CV = 2.7 % [2.2 to 3.4 %], SWC = 0.03 s) and 20 m sprint (CV = 4.9 % [4.1 to 6.4 %], SWC = 0.06 s) performances. This battery of anthropometric and physical fitness field tests observed a high level STR and produced SWC values that will permit talent development (TD) practitioners to implement SWC % to assess changes in player growth, maturity and physical fitness. Research study 2 (Chapter 5) aimed to quantify the relative-age effect (RAE) and examine differences in physical phenotypes owing to the RAE of 731 (U11 to 18) elite youth soccer players sampled from 17 UK soccer development centres. Chi-squared analysis identified a clear un-even birth distribution across all age groups, demonstrating an over-representation of players born in the first quartile (Q1) (U11 to 12: 39%; U13 to 14: 46%; U15 to 16: 57%; U17 to 18: 42%) in comparison to Q4 (U11 to 12: 13%; U13 to 14: 8%; U15 to 16: 8%; U17 to 18: 14%) of the selection year that significantly differed to the distribution expected from National census data (all ≤ 0.001). Small to moderate differences in player stature and body-mass were identified for U11 to 14 players, whereby players born in Q1 were both heavier (ES = 0.48 to 0.57) and taller (ES = 0.62 to 1.06) than players born in Q4. U11 to U12 and U17 to 18 players born in Q1 were generally (ES = 0.37 to 0.70) more mature than their relatively younger (Q4) counterparts. There were no significant differences in agility (P = 0.108 to 0.643), 10 m (P = 0.122 to 0.886) and 20 m (0.090 to 0.911) sprint times between Q1 and Q4 players. However, relatively younger (Q4) U15 to U16 players showed small to moderate (ES = 0.34 to 0.49) inferiority in MSFT performance that continued for Q2 (Q2 vs. Q4: P = 0.041, ES = 0.91). The obvious birth distribution bias identified within this chapter favours the selection of players who are born earlier in the selection year, who possess enhanced maturity related anthropometric and aerobic performance characteristics. Study 3 (Chapter 6) assessed the contribution of relative age, maturity and physical phenotypes upon soccer playing position allocation (goalkeeper [GK], central-defender [CD], lateral-defender [LD], central-midfield [CM], lateral-midfielder [LM], and forward [FWD]) in 465 elite-youth soccer players (U13 to U18`s). U13 to 14 CD were identified as being relatively older than LD (ES = 0.72). CD and GK were generally taller (U13 to 14: ES = 0.49 to 1.19; U15 to 16: ES = 0.72 to 1.48; U17 to 18: ES = 0.96 to 1.58) and heavier (U13 to 14: ES = 0.64 to 1.40; U15 to 16: ES = 0.24 to 1.57; U17 to 18: ES = 0.51 to 1.32) than other players at each developmental stage and were advanced maturers at U13 to 14 (ES = 0.63 to 1.22). Position specific fitness characteristics were distinguished at U17 to 18, where LD and LM were faster than their central counterparts (10m: ES = 0.72 to 0.83; 20m: ES = 0.94 to 1.07). In summary, relative age, maturity and anthropometric characteristics appear to bias the allocation of players into key defensive roles from an early development stage, whereas position-specific physical attributes do not become apparent until the latter stages (U17 to 18) of talent development in outfield players. Study 4 (Chapter 7) assessed the development tempo of anthropometric and physical fitness characteristics according to players decimal age and maturity offset (YPHV) of 969 (U9 to U18) UK elite youth soccer players using battery of 7 field tests. Segmented regression analysis established that estimated stature increases were highest between 10.7 (CI = 10.2 to 11.2) to 15.2 (CI = 14.8 to 11.2) years, and between -3.2 (-3.5 to -2.9) to 0.8 (0.5 to 1.1) YPHV, with estimated annual growth rates of 7.5 (CI = 7.0 to 7.9) and 8.6 (CI = 8.3 to 9.0) cm·year-1 identified for decimal age and YPHV, respectively. Estimated rate of body-mass developmet was also increased (7.1 [CI = 6.6 to 7.6] kg·year-1) between 11.9 (CI = 11.5 to 12.3) to 16.1 (CI = 15.5 to 16.7) years of age, whereas when modelled against somatic maturity, body-mass increases continued at 7.5 (CI = 7.2 to 7.7) kg·year-1 from -1.6 (CI = -2.1 to -1.1) to ~4.0 YPHV, without plataeu. Estimated CMJ development tempo decreased from 2.5 (CI = 2.2 to 2.8) to 1.3 (CI = 0.7 to 1.9) cm·year-1 circa- PHV (0.6 [-0.4 to 1.6] YPHV). Estimated T-Test performance gains ceased from 15.8 (CI = 15.2 to 16.4) years of age onwards, but when modelled against somatic maturity status, improvements slowed by ~43% at 0.4 (CI = -0.1 to 0.9) YPHV. Players estimated endurance capacity increased by 169 (CI = 158 to 179) and 185 (CI = 173 to 198) m·year-1, until 16.4 (CI = 15.9 to 17.0) years and 2.1 (CI = 1.6 to 2.5) years post PHV, respectively. Estimated 10 and 20m sprint performance increased until 11.8 (CI = 11.2 to 12.5) years of age, or -1.8 (CI = -2.5 to -1.0) YPHV, before development tempo increased (31-43%) until 15.8 (CI = 15.3 to 16.3) years, or 1.2 (CI = 0.1 to 2.3) to 1.3 (CI = 0.8 to 1.8)YPHV. Findings identified that model strength for stature and body-mass was slightly higher in YPHV (r2 = 0.89) versus decimal age (r2 = 0.81). However these trends were not apparent for the development of physical fitness attributes. In addition, Chapter 7 revealed that players estimated sprint performance development markedly increased (31 to 43%) between 11.8 years and 15.8 years, or 1.2 to 1.3 YPHV. This data will provide practitioners with a guide to help forecast players’ rate of anthropometric and physical fitness characteristics development at an early stage of their development. Findings here’s suggest that TD practitioners should systematically use estimates of maturity offset to reduce the premature deselection of equally talented but slower players who may reach the same sprint capacity in adulthood, but are slightly later maturers versus there team-mates. In summary, the standardised battery of field-tests used within this thesis observed high levels of STR. There was a clear birth distribution bias that favours the selection of players’ for UK elite soccer development centres, who are born earlier in the selection year. It is likely that transient anthropometric advantages afforded to relatively older players within younger age categories act as a major contributory factor that bias the premature selection and role allocation of these players in to key defensive (GK and CD) roles, before the development of position-specific physical attributes become apparent during the latter stages (U17 to 18) of the EPPP in outfield players. / Likely to be of particular importance to TD practitioners, players’ estimated sprint performance development increased across decimal ages (11.8 to 15.8 years) spanning PHV (-1.8 to 1.3 YPHV), justifying research to further examine the intricacies between training prescription and maturity on sprint speed development. Monitoring player maturity will enable a better understanding of maturity related anthropometric and performance gains, and is likely to improve sensitivity of training prescription and physical phenotype development forecasting. Emphasising the necessity for systematic and consistent monitoring of player growth and maturity that will likely inform talent identification and development processes, and reduce the biases associated with relative age and anthropometric advantages upon talent selection and positional role allocation.

‘While performance analysts have been increasingly employed in many elite level sporting organisations, this development has arguably not been matched with a comparable level of critical scholarship addressing how performance analysts experience, understand and practice within a variety of organisational cultures’ (Huggan, Nelson & Potrac, 2015, p. 505). Specifically, the micro-political, emotional and identity experiences faced by neopphyte performance analysts as they transition into an elite rugby league coaching environment have not yet been considered. To partially address this situation, the current thesis provides a novel insight into my emotional, identity and micro-political experiences, as I endeavoured to transition into the coaching team for the first time. Data for this investigation was gathered in the form of a daily journal, based on my experiences at the Club, the University and in my home life. These journals were also discussed during monthy supervisory meetings, in order to further understand my experiences. Several interrelated themes emerged from the resulting narrative and were principally understood in relation to the work of Kelchtermans (e.g. Kelchtermans, 2009; Kelchtermans & Ballett, 2002a, 2002b), Goffman (1959, 1963, 1969), Hochschild (1979, 1983), Burke and Stets (2009) and Stryker (1980). I contend that the inherent structural vulnerability of my neophyte performance analyst position, as well as my determination to protect and advance my career meant that I had to learn to act micro-politically. I also assert that the multiple identities I possessed during this time acted cooperatively and conflictingly at different times, ultimately resulting in me not wanting to remain within my professional identity. It is hoped that through presenting the ambiguity, pathos and dynamic nature of practicing performance analysis in elite rugby league, a more grounded understanding of this topic area can be obtained.

There are evidence that high-intensity acute exercise can promote oxidative stress. High-intensity intermittent exercise (HIIE) is a type of structured physical training characterised by repeated bouts of high-intensity exercise interspersed by recovery periods. As the impact of intermittency during acute HIIE has not been extensively studied, it is possible that the repeated intensive bouts within HIIE could induce oxidative stress levels. Plasma biomarkers, including lipid hydroperoxides and markers of DNA damage, have been increasingly applied within acute exercise physiology research to measure oxidative stress. This thesis presents the experimental outcomes of research into the effect of different forms of HIIE on established and novel biomarkers of oxidative stress. For the 1st study (chapter 3) a liquid chromatography-mass spectrometry (LCMS) method was developed and optimised to measure DNA oxidation in plasma samples. Implementing a range of progressive analytical techniques, the method developed had a sensitivity to detect 8-hydroxy-2'-deoxyguanosine (8-Oxo-dG) in human plasma samples in the range of 5 – 500 nM. The implementation of this LC-MS method along with other oxidative stress biomarkers was thereafter applied to a randomised investigation of different high-intensity intermittent exercise protocols. The 2nd (chapter 4) and 3rd (chapter 5) studies considered the effect of different forms of intermittent exercise undertaken by 9 healthy, regularly active male participants (aged 21.0 ± 3.0 years). Each intermittent exercise session was performed for a total duration of 45 minutes. Each 45 minute exercise protocol consisted of 4 minute stages of high-intensity intermittent running at a mean 75% v!O2max, followed by 1 minute of passive recovery (halt of running). The experimental protocol was specifically designed to match for average speed, duration and distance but varied in either the intermittency (chapter 4) or the acceleration/deceleration (chapter 5). The effects of different forms of intermittent exercise (high, moderate, low) or different acceleration/deceleration components (high, moderate, low) in relation to oxidative stress biomarkers were determined. Results showed the absence of significant increases in all the biomarkers examined. However, significant variation in individual oxidative stress responses was observed. Within a final study, the 8-Oxo-dG method developed was compared to a widely used ELISA method, as there are indications in the literature that ELISA may overestimate 8-Oxo-dG. Determination of 8-Oxo-dG was undertaken on blood plasma samples from 30 chronic heart failure patients (males = 23, females = 7) recruited from the Academic Cardiology department at Castle Hill hospital, Hull, UK, as previous studies have characterised the heart failure syndrome to be associated with higher levels of oxidative stress. Results showed that the LC-MS method developed found no detectable levels of 8-Oxo-dG in plasma samples whereas ELISA showed quantifiable amounts of 8-Oxo-dG. Thus, this thesis presented that the impact of intermittency or acceleration/deceleration following acute HIIE does not induce significant oxidative stress as determined by plasma and serum biomarkers, including plasma 8-Oxo-dG.

Endothelial microparticles (EMP) offer an insight into the state of the endothelium and are known to be elevated in diseases characterised by endothelial dysfunction (ED) (Horstman et al., 2004; Vince et al., 2009a). EMP have also been shown to increase after exercise/endothelial stress in healthy individuals (Sossdorf et al., 2011; Vince et al, 2009) but this area remains relatively novel. The purpose of the first experiment was to quantify the effects of an acute bout of strenuous exercise on the circulating levels of EMP and to assess if this effect is different after the ingestion of an extensively researched ergogenic aid (sodium bicarbonate, NaHCO3). Seven physically active and apparently healthy males volunteered to perform 10 x 15 second (s) cycle sprints after the ingestion of either 0.03 g.kg.BW−1 NaHCO3 or 0.045 g.kg.BW−1 of a placebo (sodium chloride, NaCl) in capsules. The ingestion of NaHCO3 induced a pre exercise alkalosis as evidenced by a significantly altered resting acid base status, but had no influence on levels of EMP in healthy males. As a result, the data was combined for the two experimental groups, and the exercise produced a significantly increased level of CD105+ MP (MP; microparticles) at 90 minutes (min) and 180 min when compared with resting levels (p = 0.010, p = 0.043 respectively). The observed peak value at 90 min was also significantly greater compared to immediately post exercise (p = 0.019). CD106+ MP also increased significantly to 90 min from immediately post exercise (p = 0.020) and this was still greater at 180 min compared to post exercise (p = 0.015). It was concluded that exercise of this nature was sufficient to elicit ED, although the endothelium shows signs of endothelial repair within a matter of hours (hr). Also, it appears that pre exercise alkalosis has no effect on the attenuation of EMP quantity. Additional work was completed to verify the novel finding that CD105+ MP and CD106+ MP appear markers of endothelial function (EF), and to further examine the quantification of EMP, this time in healthy females. There was also an additional blood draw in order to assess where the maximum level of endothelial stress was occurring post exercise. In the second experiment, 10 healthy females completed the identical repeated sprints protocol as the first experiment, this time without the ingestion of NaHCO3. CD105+ MP were increased 90 min post exercise compared to immediately after exercise (p = 0.042). There was again a decline in both markers from 90 min to 180 min, although this was not significant. Furthermore, with the addition of a blood draw at 45 min post exercise, it was suggested that EMP levels appear to be rising between 45 min and 90 min post exercise, speculating this is the time point of greatest endothelial damage. Finally, shear stress was suggested as a key reason behind the increase in endothelial damage as a result of exercise, as indicated by significant changes in variables such as heart rate (HR) and systolic blood pressure (SBP). The third experiment employed a longer 90 min interval cycling protocol with the purpose of quantifying EF over a greater period of time, allowing investigation into whether the markers of EF were altered in the same way as the previous two experiments. It was also an aim to further assess the possible influence of shear stress factors on ED. Fourteen healthy males completed 90 min of high intensity aerobic exercise, and there were several changes in both CD105+ MP and CD106+ MP. CD105+ MP rose significantly from rest to an observed peak at 90 min (p = 0.019). Both of these markers indicated a significant restoration of the endothelium as indicated by a fall from peak values during recovery to 180 min post exercise (CD105+ MP, p = 0.009; CD106+ MP, p = 0.022). This experiment concluded that the endothelium is greatly affected by highly intense exercise over a prolonged period of time, but is recovered fully in a time period of 3 hr. The effects of shear stress again appear to be largely influential, but future work must now be conducted in order to build on the findings from this research and examine shear stress closely during exercise and its relationship with EMP quantification. It was the aim of the next experiment to investigate two separate methods of assessing EF (EMP and EndoPAT-2000), this time in a group of sedentary, but otherwise healthy individuals, in order to monitor the changes as a result of an acute bout of moderate intensity acute exercise. There were no significant differences found in EF as a result of exercise. This was indicated by no significant changes in CD105+ MP concentrations from pre to post exercise (p = 0.84) or pre to 60 min post exercise (p = 0.612). CD106+ MP concentrations showed a decrease from resting values (2513 CD106+ MP per μl platelet free plasma; PFP) to immediately post exercise (1368 CD106+ MP per μl PFP, p = 0.09), and again at 60 min post exercise (1293 CD106+ MP per μl PFP, p = 0.073) compared to resting values. Additionally, EndoPAT scores were unaffected by exercise, with values of reactive hyperaemia index (RHI) changing from rest (2.43) to post exercise (2.57), but this was not significant (p = 0.35). Correlations were carried out in order to determine and comparisons that may have existed between EMP and EndoPAT score using RHI. Although there was a slight trend for the higher numbers of CD105+ MP to correlate with the lower scores of RHI (r = 0.327) this was not significant (p = 0.171). CD106+ MP showed no correlations with RHI (r = -0.087, p = 0.717). This chapter suggested that exercise was not strenuous enough to see any significant changes in EF, and EMP continue to appear efficient markers of EF in a population of sedentary, healthy individuals. The final experimental chapter investigated the effects of a supervised 8 week moderate intensity exercise programme on women with polycystic ovary syndrome (PCOS) and control women free from any known disease. The aim was to assess if this type of exercise could improve EF in this population, and if there was a relationship with EMP (CD105+ MP and CD106+ MP) to other factors, such as body composition and cardiorespiratory fitness. EF was improved from baseline values to post exercise programme, with CD105+ MP concentrations reducing from 2113 CD105+ MP per μl PFP to 424 CD105+ MP per μl PFP (p = 0.025). Furthermore, control women showed no significant change from pre to post exercise programme in CD105+ MP (p = 0.25), or CD106+ MP (p = 0.99). Further analysis was performed to look for any associations with the changes in EMP compared to body composition changes as a result of exercise, but no significant correlations existed. This study concluded that supervised, moderate intensity exercise independent of substantial weight loss was enough to elicit an00 improvement in EF in women with PCOS compared to healthy control women. Additionally, EMP concentrations appear to be able to effectively map changes in EF across a long period of time in diseased states, adding to the notion that EMP may account for EF. Future work must now build on these findings from this research and examine this response in a larger cohort involving PCOS women with varied phenotypes and body composition.

Recent professionalization, the emergence of, and ever-increasing popularity of limited overs cricket, have resulted in traditional playing schedules evolving and expanding. Consequently, players now compete for much of the year, experiencing periods of condensed fixtures. To meet these increased demands, the aforementioned contribute to effecting team performance and player health. Thus, the prevalence of injuries, especially amongst fast bowlers, has been shown and attributed to rises in competition workloads. Therefore, the main aim of this thesis was to explore the application of micro-electro-mechanical systems (MEMS) to quantify the training load of fast bowlers. Furthermore, I sought to assess relationships between both internal and external training load variables and proposed markers of fatigue and recovery. The first preliminary descriptive research study (Chapter 4) aimed to prospectively quantify fast bowling workloads during a typical season of professional domestic county cricket (April – September). Data were collected from fixture scorebooks, with descriptive bowling workloads determined by calculating frequencies of overs and deliveries bowled. This was further calculated dependant on both bowler classification (opening [O-B; n = 2] or support [S-B; n = 6]) and competition format (multiday [MD], One-day [OD] or Twenty20 [T20]), respectively. Significant differences were found in total number of overs (296.1 overs; 95% CI 37.8 to 554.4; P = 0.03) and deliveries (1764.8 balls; 95% CI 183.0 to 3346.7; P = 0.03) bowled between O-B and S-B, respectively. Multiday cricket was the only format where, significant differences between bowlers were found; total number of overs (289.9 overs; 95% CI 88.2 to 491.6; P = 0.01) and deliveries (1739.3 balls; 95% CI 529.3 to 2949.3; P = 0.01) bowled. The aim of experimental study one (Chapter 5) was to assess the between-match and within-match between-over variability of external training load measures during T20 cricket competition. MEMS data were collected from eight fast bowlers in 17 matches of domestic T20 competition, spanning two seasons. MEMS variables were categorised into total distance (TD), low- (≤ 14.4 km.h-1) and high- (≥ 14.4 km.h-1) speed running distance, total sprint distance (≥18 km.h-1), number of sprint efforts and PlayerLoadTM ([PL] arbitrary units; AU). Data were log-transformed to provide the coefficient of variation (CV; expressed as percentages). The between-match variability was greatest in high-speed running distance (32.9% CV), total sprint distance (49.0% CV) and number of sprint efforts (48.0% CV). Similarly, within-match between-over high-speed running distance (12.8% CV), total sprint distance (17.1% CV) and number of sprint efforts (12.3% CV) elicited the greatest variability, yet, this was markedly reduced compared to between-match observations. However, TD and PL were found to be relatively stable measures of external training load (range; 5.5–13.3% CV), both between-match and within-match between-over. Experimental study two (Chapter 6) investigated short-term neuromuscular fatigue (NMF) of fast bowlers and relationships to match performance during a typical season of professional academy OD limited overs cricket. Baseline measures of lower body NMF were assessed via flight time (ms) from a countermovement jump (CMJ). These measures were repeated every morning of competition; NMF was additionally assessed within 30-min after the cessation of the bowling innings (CMJ-FIRST or CMJ-SECOND). MEMS data were collected from six fast bowlers, with supplementary descriptive fast bowling workloads classifications (LOW, MODERATE and HIGH). There were significant reductions in flight time pre to post bowling innings (Δ 19 ms; P = 0.008). Moreover, similar reductions in flight time were found in LOW – MODERATE (Δ 30 ms; P = 0.03) and LOW – HIGH bowling workload groups (Δ 43 ms; P = 0.003), respectively. Finally, experimental study three (Chapter 7) investigated neuromuscular, biochemical and endocrine markers of fatigue after four spells of simulated fast bowling. Eleven fast bowlers completed differing spells of simulated fast bowling based on the Cricket Australia-Australian Institute of Sport (CA-AIS) fast bowling skills test. NMF were assessed via flight-time from a CMJ; pre (-0.5-h) and post (+0.5 and +24-h) simulation, with blood (Creatine kinase; CK) and saliva (Cortisol; sCort) samples collected in parallel. During each simulated fast bowling trial (4-, 6-, RANDOM- & 10-overs), internal (heart rate exertion index [HREI]) and external (PL) training load was quantified using MEMS. There were small, significant reductions in CMJ flight time pre to post (Δ 21 ms; P < 0.01) and pre to 24-h post (Δ 8 ms; P = 0.001) simulation, respectively. Overs bowled appeared to significantly affect NMF for up to 24-h post simulation. Furthermore, changes in CK were found to best correlate with estimated TD (r = 0.48; P = 0.002) rating of perceived exertion (RPE r = 0.47; P = 0.002) session-RPE (r = 0.48; P = 0.002), HREI (r = 0.45; P = 0.003) and PL (r = 0.41; P = 0.009) 24-h post simulation, respectively. The findings of this thesis demonstrate that during limited overs cricket, high-speed locomotive activity is highly variable amongst fast bowlers. Furthermore, fast bowlers are shown to experience short-term NMF, which appears to be magnified based on descriptive fast bowling workload characteristics. Collectively, these findings have importance for practitioners, who seek to facilitate performance by informed training prescription based on replicating match and training demands.