The accumulated stresses of training and competition may temporarily cause impairments in an athlete’s physiological and muscular function, leading to suboptimal performance levels. Cold-water immersion (CWI) has become a widely used post-exercise recovery method to accelerate the recovery process by purportedly reducing the symptoms associated with exercise-induced muscle damage (EIMD). However, the underlying physiological mechanisms, which mediate the effects of CWI, are not well understood. Therefore, the aim of this thesis was to investigate the influence of cold-water immersion (CWI) on limb blood flow and thermoregulatory responses following different modes of exercise. In study 1 (Chapter 4), the reliability of Doppler ultrasound in the assessment of superficial femoral artery blood flow (FABF) was examined under resting conditions. A Doppler ultrasound scan of the superficial femoral artery was measured on eight recreationally active male participants; twice on the same day separated by 5-min (within-day), and on a separate day (between-days). The coefficient of variation (CV) for mean blood flow (MBF) was ~16 % and ~20 % for within and between-days, respectively. A relatively small standard error of measurement (SEM) was found both within day, 13.30 mL·min-1 (95% CI, -14.79 to 38.40 mL·min-1) and between-day, 17.75 mL·min-1 (95% CI, -40.12 to 30.88 mL·min-1) for MBF differences. These findings suggest duplex Doppler ultrasound is a reliable method to collect measurements of FABF under resting conditions. The purpose of study 2 and 3 was to determine the influence of different degrees of water immersion cooling on FABF and cutaneous blood flow (CBF) and thermoregulatory responses after endurance (Chapter 5) and resistance (Chapter 6) exercise, respectively. Participants completed a prescribed endurance of resistance exercise protocol prior to immersion into 8 ºC (cold) or 22 ºC (cool) water to the iliac crest or rested non-immersion (CON) in a randomized order. Limb blood flow and thermoregulatory responses were measured before and up to 30-min after immersion. In both studies, thigh skin temperature (Tskthigh) (P < 0.001) and muscle temperature (Tmuscle) (P < 0.01) were lowest in the 8 ºC trial compared with 22 ºC and control trials. However, femoral artery conductance (FVC) was similar after immersion in both cooling conditions and was reduced (~50-55 %) compared with the CON condition 30-min after immersion (P < 0.01). Similarly, there was a greater thigh (P < 0.01) and calf (P < 0.05) cutaneous vasoconstriction during and after immersion in both cooling conditions relative to CON with no differences noted between 8 and 22 ºC immersion. Together, these findings suggest that colder water temperatures may be more effective in the treatment of EIMD and injury after both endurance and resistance exercise, respectively, due to greater reductions in Tmuscle and not limb blood flow per se. The aim of study 4 (Chapter 7) was to compare the influence of CWI and whole body cryotherapy (WBC) on FABF and CBF and thermoregulatory responses after endurance exercise. On separate days, participants completed a continuous cycle ergometer protocol before being immersed semi-reclined into 8 ºC water to the iliac crest for 10 min (CWI), or exposed to 2.5 min (30 s -60 ºC, 2 min -110 ºC) WBC in a specialized cryotherapy chamber, in a randomized order. Limb blood flow and thermoregulatory responses were measured before and up to 40-min after immersion Reductions in Tskthigh (P < 0.001) and Tmuscle (P < 0.001) were larger in CWI during recovery. Similarly, decreases in FVC were greater (~45-50 %) in the CWI condition throughout the recovery period (P < 0.05). There was also a greater skin vasoconstriction observed in CWI at the thigh (P < 0.001) and calf (P < 0.001) throughout the post-cooling recovery period. These results demonstrate that CWI may be a better recovery strategy compared with WBC due greater reductions in both Tmuscle and limb blood flow. This thesis provides a novel insight into the influence of different degrees of water immersion cooling, as well as WBC, on limb blood flow and thermoregulatory responses after different modes of exercise. These findings provide practical application for athletes and an important insight into the possible mechanisms responsible for CWI in alleviating inflammation in sport and athletic contexts.

Exercise participation is linked to mental health and wellbeing. However, we need to identify optimal settings for promoting exercise-associated wellbeing outcomes, and for promoting exercise adherence. The literature suggests environmental settings may be important. The aim of this thesis was to rigorously test influences of environmental settings on exercise-related wellbeing outcomes. These over-arching research questions guided the experimental chapters: (i) is there an optimal green exercise environment for promoting wellbeing? (ii) When exercise is controlled, are findings consistent with previously reported psychological outcomes? (iii) Do environmental settings influence social outcomes of exercise or intentions to repeat exercise behaviours? Via field-based sampling, Chapter 3 found large proportions of affective benefits were universally obtainable across four typical green exercise environments, and suggested that the processes component of green exercise warranted further investigation; however, this method lacked control. Chapter 4 used laboratory-based methodology to control exercise and isolate the visual environment; consistent with both theory and previous research, nature environments facilitated wellbeing-related attention restoration. However, this method did not provide an accurate multisensory experience, therefore lacking ecological validity. Chapter 5 investigated methodologies for controlling the exercise component, comparing wellbeing-related outcomes of indoor versus outdoor exercise. This was important because previous research had not rigorously controlled exercise, therefore potentially confounding its findings. Results for environment-related exercise differences and affective outcomes were inconclusive. Chapter 6 merged laboratory-based methods with the indoor versus outdoor exercise paradigm, ensuring control and ecological validity. Environmental setting did not influence perceived exertion or mood; green settings promoted attention restoration and social interaction; for green exercise, social interaction predicted exercise intentions. Green exercise promotes wellbeing improvements; environmental influences on affective outcomes may be contributed to by differences in exercise performed. Independent of exercise differences, green environments promote attention restoration and social interaction during exercise, which may in turn influence exercise intentions.

Application of GPS technology in elite level soccer is a growing area of research. This thesis comprises an examination of current practice in elite youth level soccer, and a critical examination of the potential applications in the PlayerLoadTM measure to quantify the biomechanical demands of match play. The thesis comprises four experimental studies that consider the development of monitoring biomechanical intensity in training and/or competitive matches. The first experimental study provides a critical examination of the biomechanical specificity of training drills relative to competitive match play. This study utilised the performance metrics as collated on a daily basis by the football club. Specifically, in relation to tri-axial accelerometry the measurement of PlayerLoad was restricted to total accumulated loading. Additional parameters related to distance and velocity parameters were also examined. ‘Small-Sided Games’ generated similar values to 90-min matches for PlayerLoad (standardised for duration) and total distance covered. However, these drills failed to provide a valid demand in terms of high-intensity running, which was most valid in ‘Movement Pattern’ drills. Drills described as ‘Possession’ and ‘Game-Related’ failed to match the mechanical demands of match play. The implications of these findings relate directly to the micro-design of the training week, and the monitoring of player performance. The correlation between PlayerLoad and distance covered was stronger in small-sided games (r=0.92) than in regulation 11 vs 11 match play (r=0.37), highlighting mechanical issues in the calculation of PlayerLoad. The smaller pitch size is likely to promote a greater frequency of speed and or directional change, and as such the summation principle applied to generate a “total” or 3- dimensional loading value is limited. 6 In the second experimental study the analysis of tri-axial accelerometry was extended to provide a uni-axial consideration of PlayerLoad. Biomechanically, this is analogous to analysing each force vector rather than the development of a “total” kinetic parameter based on a summation principle. This uni-axial analysis of mechanical loading was first applied to the influence of playing age via a comparison of the U16, U18 and U21 squads within the same club. The U16s performed the greatest total distance, primarily in the lower speed zones. Correlation between PlayerLoad and total distance ranged from r=0.26-0.56, for the three age groups, with evidence of higher coefficients in the U16 group. The U18s exhibited the greatest PlayerLoad, evident in each movement plane. Uni-axial analysis highlighted a higher contribution from medio-lateral loading in the U18s, indicative of greater lateral movement. This finding might also relate to the higher injury incidence observed in this U18 age group. The practical applications of this study relate to the transition of players through the academy structure and into senior football. The unique movement patterns identified by a uni-axial analysis of PlayerLoad highlights potential in the greater analysis of movement. This uni-axial analysis was extended in the third experimental study to further examine issues in the movement profile with a consideration of the influence of playing position on mechanical loading. Whilst not generalisable beyond this team and playing strategy, attackers covered the greatest (total and high speed) distance, whilst midfielders exhibited the greatest load across all movement planes. Correlation between PlayerLoad and total distance was position specific, forwards and midfielders recorded values of r=0.74 and r=0.16 respectively. Playing position categorising defenders, midfielders and attackers failed to identify the impact of positional width on the biomechanical demands of match play. The traditional grouping of playing units might therefore be considered in terms of individualising training programmes. The distinction between distance covered and PlayerLoad is consistent throughout the first three experimental studies, with a low correlation in part explained by the calculation used to 7 quantify PlayerLoad. In the final experimental study the PlayerLoad calculation is critically examined beyond the uni-axial nature of acceleration. Having previously examined the summation principle, the failure of the PlayerLoad calculation to consider magnitude of acceleration is examined. The instantaneous change in acceleration is not influenced by the magnitude of acceleration, and in the final study a novel iLoad parameter is introduced which is analogous to the iEMG parameter utilised widely in electromyography. This parameter considers the integral of the acceleration-time curve. Further, the sign principle is critically examined, with the PlayerLoad calculation negating all negative values and thus making all movements forward, to the right, and upward. By considering both positive and negative values the tri-axial accelerometer has the capacity to differentiate between medial and lateral movement for example, with clear implications for the monitoring of performance and injury risk. This novel biomechanical analysis was applied to an examination of fatigue during match play, which has implications for both performance and injury. Over 15min segments of match play, fatigue did not influence the anterio-posterior or medio-lateral loading but there was a significant decrease in vertical load. There was also evidence of movement asymmetry in each plane, favouring movements forward and to the left. Correlation between iLoad and total distance was r=0.19. In conclusion, the thesis evaluated PlayerLoad and critically discussed the mechanical specificity of training activities. Furthermore, use of uni-axial load highlighted differences in positional demands and the influence of age group on GPS variables. Critical evaluation of PlayerLoad calculation aimed to highlight the deficiency of tri-axial acceleration of the formula. Thus, iLoad further developed calculation to refine movement quality data to examine fatigue. By adopting principles analogous to kinetic analyses in force platform and electromyography, additional analysis parameters may be defined which provide greater depth 8 of information in movement quality. The implications in movement asymmetry also have implications for the monitoring of injury risk.

The overarching aim of the current thesis was to assess the well-being and ill-being correlates of two perfectionism dimensions (i.e., self-oriented and socially prescribed perfectionism) in hearing and deaf athletes. In Study One (Chapter Two), a cross-sectional approach revealed the similarities in the relationships between self-oriented and socially prescribed perfectionism and the broader array of burning out symptoms in deaf and hearing athletes. Study Two (Chapter Three) adopted a longitudinal design, and examined whether self-oriented and socially prescribed perfectionism predicted changes in enjoyment and subjective vitality over four months, as well as whether changes in exhaustion over the same time period mediated the hypothesised relationships. A further purpose of study two was to examine whether the hypothesised relationships were invariant across hearing and deaf athletes. Study Three (Chapter Four) adopted qualitative semi-structured interviews to gain a deeper understanding of high self-oriented and socially prescribed perfectionism in deaf and hearing athletes using a self-regulation framework. The majority of the findings suggest that self-oriented and socially prescribed perfectionism function in a similar manner across deaf and hearing athletes. It is hoped that the findings presented in this thesis may inform future research in deaf athletes to help protect this growing population from the perils of perfectionism.

Endurance exercise improves health partly though improvements in skeletal muscle function. Mitochondrial biogenesis is one of the mechanisms that underpin the positive health benefits of endurance exercise. Endurance-exercise and energy sensitive pathways signal to promote transcriptional processes that initiate the adaptive response. Thus the aim of this thesis was to further understand the regulation of post-exercise signalling within skeletal muscle, with specific focus on the activation of energy-sensitive mitochondrial biogenic signalling pathways. It was demonstrated that muscle-specific knockout of p53 does not impair mitochondrial protein content or enzyme activity within mouse skeletal muscle. In human skeletal muscle, fasting and fasted-exercise augment CREB\(^S\)\(^e\)\(^r\)\(^1\)\(^3\)\(^3\) and AMPK\(^T\)\(^h\)\(^r\)\(^1\)\(^7\)\(^2\) phosphorylation, while the mRNA expression of \(PDK4\) but not \(PPARGC1A\) is also increased in the fasted state. Finally, one week of nicotinamide riboside supplementation did not alter skeletal muscle mitochondrial respiration and whole-body substrate utilisation at rest or during endurance exercise, while SIRT1 and 3 activity and \(PPARGC1A\) mRNA expression at rest and following endurance-exercise are also unaffected by nicotinamide riboside supplementation. Overall, this thesis contributes novel data to the understanding of metabolism and skeletal muscle signalling following endurance exercise and how nutrition and endurance exercise could be integrated to optimise specific adaptations.

Introduction: Scientific investigations to determine physiological demands and performance characteristics in sports are integral and necessary to identify general fitness, to monitor training progress, and for the development, prescription and execution of successful training interventions. To date, there is minimal evidence based research considering the physiological demands and physical characteristics required for the equestrian sport of Eventing. Therefore, the overarching aim of this thesis was to investigate the physiological demands of Eventing and performance related fitness in female riders. Method: The primary aim was achieved upon completion of three empirical studies. Chapter Three: Anthropometric and physical fitness characteristics and training and competition practices of Novice, Intermediate and Advanced level female Event riders were assessed in a laboratory based physical fitness test battery. Chapter Four: The physiological demands and physical characteristics of Novice level female event riders throughout the three phases of Novice level one-day Eventing (ODE) were assessed in a competitive Eventing environment. Chapter Five: The physiological demands and muscle activity of riders on live horses in a variety of equine gaits and rider positions utilised during a novice ODE, including jumping efforts, was assessed in a novel designed live horse exercise test. Results: Chapter Three reported that aside from isometric endurance, riders anthropometric and physical fitness characteristics are not influenced by competitive level of Event riding. Asymmetrical development in isometric leg strength was reported with increased levels of performance; riders reported below average balance and hamstring flexibility responses indicating limited pelvic and ankle stability, and tightness in the hamstring and lower back. Chapter Four reports that physiological strain based upon heart rate during Eventing competition is considerable and close to maximal, however blood lactate data was not supportive of this supposition. Chapter Five reports that during horse riding, riders are exposed to intermittent and prolonged isometric muscle work. During horse-riding, riders have an elevated heart rate compared to the oxygen requirements for the activity, in addition to moderate blood lactate concentrations. Conclusion: This thesis indicates that the most physiologically demanding aspect of Event riding is the light seat canter and where jumping efforts are introduced. During these positions and gait combinations, heart rate is elevated compared to oxygen uptake. Additionally, moderate blood lactate (BLa) concentrations are reported suggesting though cardiac strain is high, physical demands are moderate. The use of heart rate as a marker of exercise intensity during horse riding activities is not appropriate as it is not reflective of actual physiologic demand and BLa may be a more indicative marker of exercise intensity for equestrian investigations. There are many factors that may affect heart rate as discussed throughout the thesis, such as cognitive anxiety, heat stress and isometric muscle work. The data from this thesis speculates that the elevated heart rate is in part affected by isometric muscle work; similar physiological profiles exist in sports such as Sailing and are attributed to the quasi isometric theory. Though this thesis is not able to comprehensively conclude that physiological responses are a direct result of quasi isometrics, the data set does infer this may be a potential contributor and as such is a recommended topic for future research. Regardless of the causal mechanism, riders should be conditioned to tolerate high heart rates to enable optimal physical preparation for competition; the physical characteristics and physiological demands placed upon Event riders reported throughout this thesis provides information for coaches and trainers to consider when designing such interventions.

Hyper-resistance at the joint is one of the most common symptoms in children with cerebral palsy (CP). There are both neural and non-neural factors contributing to the observed joint hyper-resistance. Non-neural alterations to the musculoskeletal system such as a reduced muscle length, increased tendon length and an increase in joint stiffness are commonly treated by physiotherapy interventions such as stretching exercises. However, the effectiveness of these interventions in terms of improvements in function is of a low magnitude and the response of spastic muscles to stretch is poorly understood. Therefore, the main aim of the programme of work presented in this thesis was to increase the effectiveness of stretching interventions at the ankle joint. To achieve this, it is important to understand the behaviour of the medial gastrocnemius muscle and Achilles tendon in response to a stretch applied at the joint. For this first sub-goal, three experimental studies were performed. First, the relationship between joint rotation and muscle and tendon contribution during a single stretch is described. We show that a smaller Achilles tendon moment arm leads to a decrease in muscle lengthening during joint rotation. Additionally, we show that the relative stiffness of the muscle to the tendon is increased in children with CP, which further limits lengthening of the muscle during joint rotation. Secondly, we document the acute effect of stretching on medial gastrocnemius fascicle lengthening properties. It was found that medial gastrocnemius muscle stiffness cannot explain the increased ankle joint range of motion acutely following passive stretching. These studies all indicate that the lengthening stimulus to the muscle is reduced in children with CP. Therefore, to increase the effectiveness of stretching exercises, an intervention was designed with the aim to increase this stretching stimulus seen by the muscle. By performing progressive resistance training, we showed an increase in the stiffness of the tendon, and thus a reduction in the relative stiffness of the muscle to the tendon. Therefore, the amount of stretch seen by the muscle was increased. We have shown that due to this combined intervention a remodelling of muscle is possible, as we showed muscle fascicle length to increase. Even though functional benefits were limited, the proof of principle was demonstrated and future work should explore this model of intervention further.

This project is the first to investigate blood perfusion in the human hamstrings during isometric exercise with a near infrared spectroscopy (NIRS). A Kin Com dynamometer has been used to fix the knee positions and to measure torques during contractions. Both the NIRS optodes and the electromyography (EMG) electrodes were attached to the skin over the hamstrings. Previous studies used a NIRS to measure muscle blood flow in the forearm, quadriceps and calf muscles. The changes in haemoglobin concentrations were calculated using Spike 2 software. A total of 46 male volunteers participated in the four series of experiments described in this thesis. The following overall conclusions can be drawn: perfusion decreases in the hamstrings during contractions and then returns to normal levels after a period of time, changing the limb position at which the contractions are made does not affect the perfusion, warm-up exercises increase in blood perfusion for 8 minutes at 30 and 40% of MVC. The perfusion did not significantly change during an episode of DOMS or in the injured and non-injured limbs. These conclusions show the importance of warm-up before sports activities but not necessarily avoid injury. It can be concluded that there is no association between such conditions with hamstring injuries. The maintained perfusion at different conditions is a positive finding as the perfusion is not restricted indicating good delivery of oxygen despite muscle injury.

Attempts to implement dedicated evidence-based sports science research in Gaelic Football are challenging. Current structures within Gaelic Football render the sport less conducive to research analysis. The tenet that all Gaelic Footballers “are born not made” still has its adherents in today’s management circles. Atavistic attitudes to sport scientific experimentation persist. This doctorate dissertation seeks to address important issues that have the potential to maximise performance in Gaelic Football. The underlying theme of this thesis is to understand the prevalence and aetiology of injury, and the provision of researched suggestions designed to enhance performance. The first study is a detailed prospective epidemiological study of injuries sustained by Gaelic Football players during a single competitive season (Newell et al., 2006). The design of the study was based on Van Mechelen’s (1992) model of ‘sequence of prevention of sports injuries’. To date there has been no prospective epidemiological study of injuries in Gaelic Football. Two of the main findings arising from the injury surveillance study were the high incidence of hamstrings injury and the frequency of injuring occurring in the final quarter of training and games (Newell et al., 2006). As a follow-up to the initial injury surveillance study (Newell et al., 2006), the next phase of study focussed on the aetiology of hamstrings injuries and in particular to investigate if hamstrings muscle strength or functional hamstrings/quadriceps ratio (H:Q ratio) is a predictor of hamstrings injury in Gaelic Football.The linear regression model fitted to the functional H:Q data identified two players as potential hamstrings injury candidates, one of whom sustained a hamstrings injury during the playing season. A subsequent intervention programme aimed at reducing the incidence of hamstrings injury was devised but team managers were generally unwilling to embrace an intervention as they did not wish, as they saw it, to interfere with components which were essential for player preparation. Dehydration is a recognised risk factor for injury, although the direct evidence linking dehydration and injury has not been established. The goal of the next phase of research was to investigate the fluid and electrolyte balance of individual elite (Newell et al., 2008) and club Gaelic Football players and devise personal hydration strategies, as a means of controlling the potential impact of dehydration while prospectively recording injuries. The two hydration studies (conducted in warm and cool conditions) have shown that changes to pre and post training body mass (using weigh scales), assessing pre-training hydration status (using a refractrometer, and reagent strips), and monitoring of the amount of fluids consumed during training (individualised drinks bottles) can help determine individual hydration requirements. The results of both studies indicated: a wide variation in sweat rates and fluid and electrolyte balance, evidence of pre and post dehydration, and that a single hydration strategy, based on published guidelines, is unlikely to be suitable for an entire team. Conducting regular testing during varying environmental conditions will help to establish a routine for fluid intake for all situations. Both studies provide support for an enlarged dedicated epidemiological research study to provide direct evidence linking dehydration to injury. However a study of this magnitude would require the full support of the Gaelic Football Association.

The aim of this thesis was to explore the effects of state anxiety, trait anxiety, and defensiveness on a psychomotor task that required working memory resources. Results from study 1 confirmed that a random response generation task was sensitive to changes in response rate and used limited working memory resources. ARM MANOV A showed that participant behaviour became less random as response rate increased (A. =.239, F9,1 = 14.491)