The overall aim of this thesis was to investigate modalities used as components of pre event/training preparation, to try to develop an optimal preparation strategy for sports performers. It concentrates on the stretch modalities commonly used by athletes as part of a warm-up designed to prepare them for subsequent performance. Past literature suggests that static stretching as part of a warm-up leads to a decrease in performance when compared to an active warm-up or a warm-up including dynamic stretches. Not surprisingly this has led to a movement away from static to dynamic stretches by many athletes. The presented publications were conducted to clarify a number of issues raised by past research studies. A lack of ecologically valid studies is apparent; the static stretch protocols used in most of the early research in this area has failed to explore what sports performers actually use as part of their training, while there was a lack of research examining the effect of dynamic stretches on performance. Of particular relevance is the lack of research looking at the mechanisms behind the changes in performance linked to warm-ups incorporating dynamic stretches. Therefore, this group of publications attempts to systematically examine the effects on performance of manipulating the stretch component of an active warm-up, while exploring the potential mechanisms linked to any changes in performance. The general findings of this series of papers provides evidence that static stretches, as part of an active warm-up, are linked to a decrease in the acute performance of a range of physical capabilities; including sprint, agility, jump and maximal force output. The mechanisms behind these performance changes are multifaceted, with decreases in core temperature and heart rate, decreases in musculotendinous unit stiffness and a decrease in muscular activity, when compared to a general active warm-up established. In contrast when a dynamic stretch replaces the static stretch component and is incorporated within a warm-up, performance is enhanced when compared to an active warm-up. The mechanisms behind this seem to be less temperature related and more closely linked to the neuro-muscular system. Greater muscular activity is linked to dynamic stretches, causing an increase in peak force and rate of force development, compared to an active warm-up protocol. This effect seems to be enhanced the faster and more specific the dynamic stretches are to the chosen performance measure, while combining static stretches with dynamic stretches as part of a preparation strategy still leads to decreases in performance compared to an active warm-up combined with dynamic stretches. In conclusion, to maximise acute maximal performance in sports specific motor skills, an active warm-up combined with specific dynamic stretches is recommended to sports performers and coaches.

The principle aim of this work was to provide an insight into the prevalence of the metabolic syndrome (MetS) in children and adolescents and to examine the associations of body composition measures, cardiorespiratory fitness (CRF), and physical activity with cardiometabolic risk. The combined association of adiposity and CRF on cardiometabolic risk in youths is also explored, as is the association of CRF with potentially modifiable variables, such as physical activity. This work has shown that, dependent on the definition employed, MetS may be present in 2.3% to 9.8% of children and adolescents in Bedfordshire, UK. When applying modified Adult Treatment Panel III definitions (Cook et al. 2003; de Ferranti et al. 2004), the condition was significantly more prevalent in overweight compared to non-overweight youths. Backward regression analyses identified that only body mass index (BMI) explained significant amounts of variance in clustered cardiometabolic risk, although being overweight according to internationally proposed cut points for BMI, waist circumference (WC), and waist-to-height ratio conferred participants to increased risk compared to their non-overweight counterparts. Clustered risk was also elevated in children and adolescents with low levels of CRF compared to those with high levels, whereas time spent in moderate-to-vigorous physical activity and vigorous physical activity (VPA) held no association. When stratified into groups according to level of fatness (BMI z-score) and CRF, those with high fatness/low CRF generally exhibited the most unfavourable cardiometabolic risk profiles. Cardiometabolic risk was higher in the high fatness/low CRF group compared to those with low fatness/low CRF and low fatness/high CRF when excluding WC from the score, and those with low fatness/low CRF when including WC in the score. Multiple regression and ANCOVA revealed that increased visceral fatness (indirectly measured using WC) was associated with reduced CRF, while increased time spent in VPA was associated with elevated CRF. These data suggest that BMI may be the best simple measure of obesity to employ when exploring adiposity-related cardiometabolic in children and adolescents. In addition, results from this iv investigation indicate that low CRF and overweight/obesity may have deleterious effects on the cardiometabolic health of children and adolescents and that interventions to reduce risk may target decreases in fatness and improvements in CRF and VPA as standard.

There is evidence that physical activity (PA) levels are declining in English children. Sedentary screen based media activities, including computer use and video game play have been linked to low PA levels and unhealthy energy intake (EI). These behaviours appear to be particularly prevalent in boys during mid-to-late childhood. Recent laboratory-based studies have found active video games can increase children’s energy expenditure (EE) and PA levels to moderate to vigorous levels, in comparison to matched conditions such as resting and seated video game play and so could increase children’s PA. However, the previous active video gaming studies have utilised various protocols that probably do not accurately reflect the real life active video gaming practices of children. Recently it has been established that there is EI in adolescents during active video gaming. If this is so, the EI during active video gaming could potentially counteract the EE from active video game play. The purpose of this thesis therefore, was to establish the acute appetite, EI and PA responses to active video gaming, in 8-11 y boys. There is sparse information regarding the habitual active video gaming behaviours of children during mid-to-late childhood. Consequently, in study one a questionnaire was designed specifically, to understand the real-life active video gaming practices of 40 7-11 yr-olds. By utilising the survey findings, in study two an acute intervention was designed to investigate the subjective appetite sensations (hunger, prospective food consumption and fullness), EI and PA in response to active video gaming in 21 8-11 yr-old boys. Each boy completed four individual 90 min gaming bouts in a randomised order which were; 1) seated video gaming no food or drinks, 2) active video gaming no food or drinks, 3) seated video gaming, food and drinks offered ad libitum and 4) active video gaming, food and drinks offered ad libitum. The study determined that there were no differences in acute sensations of hunger, prospective food consumption and fullness, or EI (MJ) between the seated and active video gaming bouts during which foods and drinks were offered ad libitum (bouts 3 and 4). Physical activity levels due to active video gaming were light and from seated video gaming were sedentary. Energy intake during both bouts was greater than the estimated EE, thus producing a positive relative energy balance state in the boys. As subjective appetite findings did not explain the high EI during both seated and active video gaming, the objective study of appetite was necessary. A previous adult study had established good reproducibility in GLP-17-36, glucagon, leptin and insulin by using the less invasive fingertip capillary sampling. Since fingertip capillary sampling had not been utilised to measure plasma concentrations of the above mentioned hormones in children during gaming, in study three, preliminary testing established good reliability for fasting plasma GLP-17-36 and blood glucose in 8- 11 yr-old boys. Enabling study three to compare acute satiety related signalling, subjective appetite, EI and PA in 21 8-11 yr-old boys, in response to one bout of active video gaming and one bout of seated video gaming, during which food and drinks were offered ad libitum. The satiety-related signals, namely plasma GLP-17-36 and blood glucose were measured alongside subjective appetite sensations and EI during active and seated video game play and in a post-gaming test meal. A significant increase in glucose showed the boys had consumed a greater proportion of carbohydrate (CHO) during active video gaming. However, as more total energy was consumed during seated video gaming, and plasma GLP-17-36 was higher during active video gaming, according to the ‘glucostatic theory’, there may have been a satiety response. The satiety signals may not have been strong enough to override the hedonic response to food intake, especially as fullness sensations were higher during active video gaming. Physical activity levels were light due to active video gaming and sedentary from seated video gaming and so on cessation of both bouts, the relative energy balance of the boys was positive. The positive relative energy balance state was then not compensated for by a reduction in EI in a post-gaming test meal. Instead, the additional EI resulted in an increase in the positive relative energy balance state, of the 8-11 yr-old boys. The overall findings of this thesis established that EI appears to be commonplace in the majority of 8-11 yr-old children during active video gaming. Parents should encourage their children to play active, rather than seated video games to reduce sedentary time and also discourage EI during game play.

DNA methylation, an epigenetic modification which can regulate gene transcription independently from alterations to the nucleotide sequence, can be manipulated by lifestyle factors such as diet and exercise, hypothetically reversing aberrant DNA methylation associated with disease pathogenesis. The underlying mechanisms by which these changes occur are currently poorly characterised, however, in vitro data suggest that inflammatory mediators are involved. Furthermore, regular exercise appears to reduce inactivity-associated systemic inflammation, possibly by alterations to the methylome, thereby suggesting a cyclic relationship between exercise, inflammation, and epigenetic modification. The aims of this research programme, therefore, were to: characterise the acute changes that occur to the de novo DNA methyltransferases following exercise in peripheral blood mononuclear cells (PBMCs), and the role of exercise-induced systemic inflammation in this process; investigate how these changes then translate into functional modifications to the methylome; and to determine whether a training programme utilising sedentary individuals manipulates DNA methylation of genes involved in chronic systemic inflammation associated with physical inactivity. Pilot investigations corroborated previous in vitro data that recombinant IL-6 is able to regulate nuclear concentrations of DNMT3A and DNMT3B in PBMCs. In order to isolate the influence of circulating proteins independently from genetic polymorphisms that may influence susceptibility to epigenetic change, cells were stimulated with exercise-conditioned plasma following intense endurance exercise which elicited significant alterations in nuclear concentrations of DNMT3A and DNMT3B. Eccentric exercise, which is typically not associated with elevations in circulating cytokines, did not cause any significant changes in nuclear or cytoplasmic DNMT concentration, or global DNA methylation; this supports the hypothesis that transient systemic elevations in inflammatory cytokines are important regulators of epigenetic modifications associated with exercise. Lack of transcriptional changes in DNMT3A following both exercise training and an acute maximal bout suggests that, in line with in vitro data, that the observed elevations in nuclear DNMT concentration are largely due to cellular relocalisation and not gene expression of this enzyme. It remains to be elucidated whether the training regime, and the subsequent response to an acute maximal bout, is able to elicit differential methylation of IL6, NFκB2, and ASC, however, in vitro stimulation of PBMCs with the cytokines IL-6 and IL-1β did cause significant changes to IL6 promoter methylation, further supporting the role of these proteins in epigenetic regulation. The data presented in this thesis support the postulation that exercise-induced changes to DNA methylation in PBMCs likely occur due to systemic elevations of inflammatory proteins, in particular IL-6, which causes manipulation of de novo DNMT nuclear concentrations due to cellular translocation of the enzymes themselves. While it was not possible to determine whether exercise directly modified gene-specific methylation, in vitro experiments suggest that inflammatory cytokines are able to regulate IL6 promoter methylation in human PBMCs.

Athletes and practitioners are continually looking for new strategies that could minimise the negative effects of exercise-induced muscle damage (EIMD) and hasten the recovery process. One strategy that has shown promise in recent years is the use of functional foods rich in phytonutrients. A functional food that has attracted a lot of attention recently, although primarily for its performance enhancing effects, is beetroot (Beta Vulgaris L.). In addition to displaying a range of physiological effects that may benefit athletic performance, beetroot also exhibits antioxidant (AOX) and anti-inflammatory effects, both of which could be of benefit for reducing secondary damage and enhancing exercise recovery. Nonetheless, the effect of beetroot on exercise recovery is yet to be systematically investigated in the literature. Thus, the overarching aim of this thesis was to test the efficacy of beetroot supplementation, in the form of beetroot juice (BTJ), as a recovery intervention following strenuous exercise. The series of investigations that set out to address this aim have led to many novel and interesting findings. To start with, study 1 was the first to show that a commercially available BTJ is a rich source of phytonutrients and therefore possesses a high AOX capacity in comparison to several other fruit and vegetable juices. Secondly, and perhaps the most novel finding in this thesis, was that BTJ showed promise as an efficacious recovery intervention following some bouts of muscle-damaging exercise. Although not a consistent finding throughout this thesis, BTJ was able to improve the recovery of dynamic muscle function and reduce muscle pain after eccentric-heavy exercise. Another important finding was that BTJ, despite being rich in AOXs, did not adversely affect the acute adaptive response to exercise, as measured by the repeated bout effect (RBE). In contrast to the findings in the earlier studies, however, BTJ was not found to be beneficial for recovery after long distance running. Importantly, the final study in this thesis provided the first evidence that BTJ is more beneficial than sodium nitrate (SN) for enhancing some aspects of recovery. This study highlighted the importance of the phytonutrients in BTJ other than nitrate on recovery after exercise. In summary, the collective findings of this thesis provide new information on the potential application of a phytonutrient rich functional food, in BTJ, for recovery from strenuous athletic performance.

The aim of this thesis was to develop our understanding of the Functional Re-adaptive Exercise Device (FRED): a novel prototype exercise device proposed to facilitate the activation the deep paraspinal and anterolateral abdominal wall musculature in a manner consistent with the requirements of motor control training in people with low back pain. Firstly, the intra- and interday reliability and precision of measurement of ultrasound imaging of the lumbar multifidus (LM) and transversus abdominis (TrA) were established. LM and TrA demonstrated good (ICC ≥ 0.75) to excellent (ICC ≥ 0.9) intrarater reliability for both intra- and interday measurements of absolute linear muscle thickness across all conditions. Normalised thickness change, expressed relative to resting values, also demonstrated good reliability between days, with ICCs in excess of 0.75 across all conditions. Secondly, the typical nature of LM and TrA function during this mode of exercise was evaluated in relation to commonly used assessment techniques such as the abdominal drawing-in manoeuvre, active straight-leg raise, and contralateral arm-lift. All contraction conditions successfully resulted in active relative thickness change of LM and TrA. Relative thickness change of the LM when using the FRED was favourable in that it was lower than that observed in loaded contralateral arm raise and walking conditions, suggesting that one of the key features of specific motor control training (contraction intensity of 30-40 % MVC) has been met. Thirdly, activity of the LM and TrA during this mode of exercise and other commonly used corrective/rehabilitative techniques based on relatively static challenges to stability was compared (gym ball, balance board). All stability challenges successfully induced non-volitional concomitant activation of both the LM and TrA. Additionally, it was observed that the LM followed a pattern where all standing conditions elicited greater recruitment than seated conditions, with no additional effect of surface lability. Contrastingly, the TrA only demonstrated an effect of surface instability during FRED conditions. The preferential contraction ratio of the TrA in comparison to IO and EO was greatest during use of the exercise device in the standing position. Fourthly, the intrinsic kinematic stability of the lumbopelvic region whilst using the exercise device was examined, revealing further evidence of the underlying mechanisms facilitating LM and TrA contraction. Key differences between FRED exercise and overground walking included reduced axial rotation of the trunk with respect to the pelvis (i.e. increased lumbopelvic stability) and a more anteriorly tilted pelvis. FRED exercise potentially moved the pelvis into a more advantageous position for the recruitment of TrA and LM. However, the unstable base of support afforded by FRED exercise would seem to add a challenge to movement control that could result in greater TrA and LM activity than overground walking. Finally, the pattern of global muscle activation during this exercise was examined, and provided evidence as to the tonic nature of FRED mediated muscle activity of the lumbar paraspinal and anterolateral abdominal muscles. FRED exercise a) promoted more tonic activity of the lumbopelvic musculature compared to overground walking, b) resulted in greater spinal extensor activity than spinal flexor muscles compared with overground walking, and c) resulted in greater knee extensor activity compared with overground walking.

Pacing patterns vary between sports, between athletes and between competitions. There is much literature investigating pacing patterns in laboratory and staged competitive situations which have suggested that fast start, parabolic and even pacing patterns could be optimal for short, middle and long distance events, respectively, in elite athletes. However, there is little information about optimal pacing patterns to win medals in competitive situations in middle distance events and even less information specifically for female and developing athletes. This thesis describes and explains the variation in pacing needed to win a medal in swimming and running middle distance events for male and female elite athletes using data from international competitions. Pacing patterns seen in competitive middle distance events by developing swimmers were also investigated. Following a literature review, two methodological chapters developed a suitable video data capture method and then identified a suitable sample size for the collection of retrospective data. The first experimental chapter identified that a variable pacing pattern that included a conservation period of reduced relative pace and an end-spurt of increased relative pace was optimal in order to win a medal in elite men’s 400 m freestyle swimming and 1500 m running. The second experimental chapter identified the same need for conservation of relative pace earlier in the race and an increase in relative pace for an end-spurt at the end of a race in order to win a medal in female elite 400 m freestyle swimming. The third experimental chapter identified that the same pacing patterns were optimal for age group swimmers at regional competitions but that the youngest swimmers needed to develop a more optimal performance template. The fourth and final experimental chapter of this thesis used three case studies to show that a higher training load and lower positive affect led to improved pacing patterns in developing athletes. This thesis contributes to the literature on pacing by identifying the optimal changes in relative speed needed to win a medal in competitive middle distance events.

Introduction: Recent data suggests that UK cardiac rehabilitation (CR) programmes do not substantially improve cardiorespiratory fitness (CRF) or patient survival. The exercise dose prescribed as part of a routine CR programme may be insufficient. The aims of the thesis were to (i) investigate whether a routine UK CR exercise training programme could improve peak oxygen consumption (VO₂peak) and, (ii) reduce carotid intima-media thickness (CIMT) progression in patients with coronary heart disease (CHD) and, (iii) determine whether higher exercise training doses prescribed to patients with CHD through a tele-monitoring system elicit superior VO₂peak improvements compared to routine CR alone. Study One: We recruited n=34 patients (85.3% male; age 62.1 ± 8.8 years; body mass index [BMI] 29.5 ± 4.5 Kg·m⁻²) who had recently been diagnosed with CHD. n=22 patients formed an exercise training group (TG) and undertook an eight week (16 session) low to moderate intensity (40-70% peak heart rate reserve), routine CR exercise training programme. n=12 patients declined routine CR and were assigned to a non- exercise control group (CG). Patients in the training group were followed up after completing their exercise training programme. Controls were followed up approximately 8 to 10 weeks after their initial visit (visit 2). Both groups were followed up 12 months later. VO₂peak change was determined in all patients via “gold standard” maximal cardiopulmonary exercise testing (CPET) using the modified Bruce treadmill protocol. C-IMT progression was also determined using B-mode ultrasound. In the UK, submaximal exercise tests such as cycle ergometry are typically used to assess CRF change following CR. Submaximal cycle ergometry (intensities up to 70% heart rate reserve) was used to estimate changes in CRF. Submaximal cycle ergometry showed a mean improvement of 1.64 METs (95% CI 1.20 to 2.09 METs; p<0.001). However, “gold standard” maximal CPET showed that this equated to no significant change in VO₂peak (Δ change: 0.12 ml·kg⁻¹·min-1; 95% CI -1.00 to 1.24 ml·kg⁻¹·min⁻¹). No VO₂peak improvement was detected in controls (Δ change: 0.15ml·kg⁻¹·min⁻¹; 95% CI -1.37 to 1.66 ml·kg⁻¹·min⁻¹; p=0.978). VO₂peak remained unchanged after 12 months amongst patients in the TG (Δ -0.94 ml·kg⁻¹·min⁻¹; range -6.09 to 2.10 ml·kg⁻¹·min⁻¹; p=0.846). Controls experienced C-IMT progression in the right lateral aspect of their common carotid artery (CCA) at the end of the eight week CR period (Δ change: 0.070 mm; range -0.060 to 0.200 mm; p=0.038). Patients in the TG experienced C-IMT reduction in the left lateral aspect of their CCA between CR programme completion and their 12 month follow-up (Δ change: 0.054 mm; range -0.160 to 0.020 mm; p=0.015). Study Two: We recruited n=50 healthy volunteers (60% male; age 26.2 ± 5.0 years; BMI 24.6 kg·m⁻² ) to examine the intra and inter-operator variability of automated c-IMT measurements when taken by novice operators. Two novice operators performed serial bilateral C-IMT ultrasound measurements using the CardioHealth Station (Panasonic Biomedical Sales Europe BV, Leicestershire, UK). Immediate inter-operator variability was determined by comparing operators’ initial measurements. Immediate retest variability was determined by comparing consecutive measurements (<10 minutes apart). Longer-term variability was determined by comparing operators’ initial measurements to a third set of measurements conducted one week later. Bland-Altman analysis and intraclass correlations were conducted. The limits of agreement (LoA) for immediate inter-operator variability were -0.063 to 0.056 mm (mean bias -0.003 mm). Operator 1’s immediate retest intra-operator LoA were -0.057 to 0.046 mm (mean bias was -0.005 mm). Operator 1’s intra-operator LoA at one week were -0.057 to 0.050 mm (mean bias -0.003 mm). Operator 2’s LoA were similar to those of operator 1. Novice operators produce acceptable short-term and one week inter- and intra-operator C-IMT measurement variability in healthy, young to middle aged adults using the Panasonic CardioHealth Station. Study Three: We recruited n=27 patients with a diagnosis of CHD (88.9% male; age 59.5 ± 10.0 years; BMI 29.6 ± 3.8 kg·m⁻²). VO₂peak change was quantified in n=10 patients receiving routine CR plus personalised exercise training based on maximal CPET data delivered via a bespoke tele-monitoring device. VO₂peak change was also determined in n=17 patients receiving routine CR only. CPET was performed using a 25W stepped cycle ergometry protocol. The combination of routine CR and a bespoke exercise training programme significantly increase VO₂peak (Δ change: 2.08 ml·kg⁻¹·min⁻¹; 95% CI 1.88 to 3.97 ml·kg⁻¹·min⁻¹; p=0.014) compared to routine CR alone (Δ change: -0.29 ml·kg⁻¹·min⁻¹; 95% CI -1.75 to 1.16 ml·kg⁻¹·min⁻¹; p=0.841). Conclusions: An eight week (16 session) low to moderate intensity (40-70% peak heart rate reserve) CR exercise training programme, typical of many programmes in the UK, does not improve direct measurements of VO₂peak on treadmill or cycle ergometer protocols. Current assessment methods utilising submaximal exercise testing may be overstating the effect of CR exercise interventions on CRF. Current UK recommendations for exercise training doses may also be inadequate. Data within study three indicates that a minimum of 13 sessions over a 12 week period may be required to improve VO₂peak. Limited evidence indicates that routine CR with structured exercise training may attenuate C-IMT progression compared with usual care control participants. This anti-atherosclerotic effect may be related to lower coronary risk factors and better adherence to other secondary prevention measures. Overall, higher exercise training doses and personalised exercise prescription derived from maximal CPET data appeared necessary for attaining significant CRF improvements in patients with CHD.

In the sports industry, media rights, sponsorships and gate revenues are the predominant engines for growth and are based on the support of loyal fans that drive the profit potential for teams, corporate sponsors and broadcasters alike. A declining fan base can result in low revenues and disappointing profits. Literature to date has focused predominantly on the determiners and motivational aspects of fan loyalty, at the expense of understanding the deterioration of the relationship between the sports fan and the sports team. This research investigated the concept of sports fan detachment and the dissolution process of lapsed season ticket holders of the Blue Bulls rugby franchise. An extensive review of team identity and fan loyalty literature was undertaken together with the integration of brand detachment theories into a conceptual model. A qualitative study with 14 lapsed Blue Bulls season ticket holders resulted in the sports fan dissolution process being defined and characterised. In-depth interviews provided a means to probe and understand the respondents’ experiences and insights. The research confirmed that sports fans progress through a three stage process of dissolution including the dissolution stage (breakdown trigger, breakdown phase and decision trigger), exit stage and post dissolution stage. The breakdown triggers were characterised as interpersonal, intrapersonal or structural in nature. The breakdown phase of sports fan detachment takes place over time and is iterative in order to break the bonds with the sports object. The process is largely sequential in nature. A model of the sports fan dissolution process was developed to illustrate and summarise the findings of the research. The aim of the model is to provide a profiling framework for sports organisations to tailor their CRM programmes to reverse the process of sports fan detachment. / Dissertation (MBA)--University of Pretoria, 2013. / mngibs2014 / Gordon Institute of Business Science (GIBS) / MBA / Unrestricted

Peripheral arterial disease (PAD) is a chronic atherosclerotic disease, primarily affecting the lower limbs. The associated intermittent claudication (IC) is a muscle pain/cramping sensation in the legs, primarily brought on by physical activity, such as walking, which can negatively affect daily function and quality of life. Poorer levels of lower-limb muscle strength are strong predictors for mortality and the plantarflexor muscles in particular are a frequent site of claudication pain, with previous literature also indicating their dysfunction during level gait. However, little is known about the size and architecture of these muscles, the quality of the in-series Achilles tendon or the factors that contribute to voluntary joint moments and how these relate to physical function in this population. The aim of this thesis was to determine the functional properties of the gastrocnemii muscles and Achilles tendon in order to make evidence-based clinical recommendations for specific exercise interventions for claudicants. A total of 23 participants (13 claudicants and 10 controls) took part in the study. Muscle-tendon dimensions and architecture, tendon properties, activation patterns and muscle strength, power and quality (specific tension) were assessed be integrating ultrasound imaging, electromyography and dynamometry. Stair gait biomechanics were analysed using 3D motion capture as indicators of whole body physical function. Within the claudicant cohort, disease severity was determined using the ankle brachial pressure index and walking performance assessed by a modified six-minute walk test. Average post-exercise ankle brachial pressure index of the claudicating-limbs were 0.55±0.21 with initial (onset of claudication pain) and absolute (maximal claudication pain) walking distances of 105±45m and 265±136m, respectively. The first study investigated the relationships between the resting architecture of the gastrocnemii and functional properties of the Achilles tendon with disease severity and walking endurance. Worse disease severity was significantly associated with longer fascicle: tendon length ratios in both lateral (R=-.789, P=.001) and medial (R = -.828, P = < .001) gastrocnemius, and increased tendon hysteresis (R=-.740, P=.006). This suggests that the Achilles tendon has undergone deleterious changes and the muscle has adopted a structure designed to compensate for this. However, the concomitant associations with poorer walking endurance indicate this mechanism is not effective. Walking endurance could also be explained by lateral and medial gastrocnemius pennation angle, maximum tendon force, tendon hysteresis and disease severity (R2=~0.6). The direction of coefficients within these models suggests that improving tendon properties and increasing strength, but without increasing pennation angle, would be beneficial for walking endurance. Thus, eccentric resistance training may be an effective exercise intervention. The second study investigated relationships between static and dynamic muscle quality with disease severity and walking endurance. The power-producing capabilities of claudicants’ plantarflexors (both the claudicating/painful limb and asymptomatic limb) were impaired compared to healthy controls, particularly at high contraction velocities (24% difference at 180°/s). This could be explained by some reduction in gastrocnemii muscle quality and a greater reliance on the prominently type I fibred soleus muscle. As reduced dynamic capability of the plantarflexor muscles was associated with disease severity (R=.541, P=.037) and walking endurance (R=.689, P=.006), high velocity resistance training of the plantarflexor muscles appears important to maintain functional performance. The third and fourth studies investigated the functionally challenging daily tasks of stair ascent and stair descent, respectively. During stair ascent, plantarflexor moments were similar in claudicants compared to healthy controls, indicating the muscle could meet the strength demands of this task. We also observed that ankle angular velocity at the instant of peak moment, peak ankle power generation, as well as propulsive and vertical forces, were all reduced during forward continuance in the claudicating-limb group. It seems that claudicants possess adequate levels of strength when moving more slowly but are unable to remain strong when moving more quickly, therefore it could be suggested that the slower walking speed is a means to allow claudicants to operate within safer limits relative to their maximal strength capacity. This provides further evidence, in a functional context, of the velocity-dependent limitations of the plantarflexors detected in study two. During stair descent we hypothesised that the task demands would be redistributed away from the affected plantarflexors towards the muscles surrounding the hips and knees. Instead, the claudicants placed a greater reliance on the plantarflexors compared to healthy controls (40% vs 28% of plantarflexor contribution to peak support moment). Additionally, a unique hip extensor strategy was exposed during weight acceptance that was adopted by 73% of the claudicating-limb group, which was also associated with increased disease severity. However this was not a mechanism to reduce the functional demands on the plantarflexors but rather to reduce demands on the knee musculature. These data indicate the claudicants were relying heavily on the functionally limited plantarflexors to absorb the falling body mass during weight acceptance in stair descent, which may pose an increased risk of falling. This thesis has identified important changes in the structure and quality of the gastrocnemii muscles and the properties and function of the Achilles tendon, that appear to influence whole body function during demanding and risky physical activities (stair negotiation) that necessitate alternate strategies. Taken as a whole, it is clear that high-velocity and eccentric resistance training would likely improve the musculoskeletal characteristics of claudicants, increase walking endurance and facilitate safe stair negotiation.