Background: Although physical inactivity has been linked with numerous chronic health conditions and overall mortality, the majority of English adults report insufficient physical activity. To increase population physical activity levels, researchers have called for more community-level interventions. To evaluate these complex public health interventions, innovative study designs are required. The aim of this thesis was to evaluate whether a community-level physical activity intervention—‘Devon Active Villages’—increased the activity levels of rural communities. Methods: The Devon Active Villages intervention provided villages with 12 weeks of physical activity opportunities for all age groups. Community engagement helped tailor activity programmes for each village; communities were then supported for a further 12 months. 128 rural villages from south-west England were randomised to receive the intervention in one of four time periods, as part of a stepped wedge cluster randomised controlled trial. Data collection consisted of a postal survey of a random sample of adults (≥18 years), at baseline, and after each of the four intervention periods. The primary outcome of interest was the proportion of adults who reported sufficient physical activity to meet the current guidelines (≥150mins of moderate-and-vigorous, or ≥75mins of vigorous-intensity activity per week). The number of minutes spent in moderate-and-vigorous activity per week was analysed as a secondary outcome. Using data from all five periods, a comparison of study outcomes between intervention and control arms was performed, allowing for time period (as a fixed effect), and the random effect induced by correlation of outcomes (clustering) within villages. Additionally, the baseline data were analysed separately using logistic and linear regression models to examine the correlates of physical activity behaviour in rural adults. Results: Baseline study: 2415 adults completed the postal survey (response rate 37.7%). The following factors both increased the odds of meeting the recommended activity guidelines and were associated with more leisure-time physical activity: being male, in good health, greater commitment to being more active, favourable activity social norms, greater physical activity habit, and recent use of recreational facilities. In addition, there was evidence that younger age, lower body mass index, having a physical occupation, dog ownership, inconvenience of public transport, and using recreational facilities outside the local village were associated with greater reported leisure-time physical activity. Main study: 10,412 adults (4693 intervention, 5719 control) completed the postal survey (response rate 32.2%). The intervention did not increase the odds of adults meeting the physical activity guideline, although there was weak evidence of an increase in the minutes of moderate-and-vigorous-intensity activity per week. The ineffectiveness of the intervention may have been due to its low penetration—only 16% of intervention participants reported being aware of the intervention, and just 4% reported participating in intervention events. Conclusions: Baseline study: This study highlights potentially important correlates of physical activity that could be the focus of interventions targeting rural populations, and demonstrates the need to examine rural adults separately from their urban counterparts. Main study: A community-level physical activity intervention providing tailored physical activity opportunities to rural villages did not improve physical activity levels in adults. Greater penetration of such interventions needs to be achieved for them to have any chance of increasing the prevalence of physical activity at the community level.

The hyperbolic relationship between power output and endurance time can be measured using all-out exercise. The aims of this thesis were to (i) assess whether the all-out test could be used under novel testing protocols to provide valid power-duration (P-D) parameter estimates; and (ii) attempt to elucidate the likely physiological composition of the P-D curvature constant. All-out tests were initiated from moderate-(M), heavy-(H) and severe-(S2 & S4) intensity ‘baselines’ (chapter 4). The work performed above end power (WEP) was not different to control under M or H conditions but was significantly, predictably reduced under the S2 & S4 conditions (control: 16.3 ± 2.2; M: 17.2 ± 2.4; H: 15.6 ± 2.3 kJ, P > 0.05; S2: 11.5 ± 2.5; S4: 8.9 ± 2.2 kJ, P < 0.05). The 3-min all-out test end power (EP) parameter was unaffected. Muscle glycogen may form part of the WEP. Type I (T1) and type II (T2) muscle fibres were depleted of their glycogen content prior to the all-out test (chapter 5). EP and WEP were unaffected by either T1 or T2 glycogen depletion. The all-out tests was conducted under hypoxic conditions alongside the criterion assessment of the P-D relationship (chapter 6). Normobaric moderate hypoxia caused a reduction in CP (control: 175 ± 25; hypoxia: 132 ± 17 W, P < 0.001) without affecting W′ (control: 13.2 ± 2.2; hypoxia: 12.3 ± 2.7 kJ, P > 0.05). The 3-min all-out test provided EP and WEP estimates, which did not differ to CP and W′ (control: EP 172 ± 30 W, WEP 12.0 ± 2.6 kJ; hypoxia EP 134 ± 23 W, WEP 12.5 ± 1.4 kJ, P > 0.05) providing the ergometer resistance was adjusted for the hypoxic conditions. Furthermore, a significant negative relationship was observed between %∆ ( O2peak – CP) and %∆W′ (r = -0.83, P < 0.001); thus, W′ may represent the relative ‘size’ of the severe-intensity domain. The all-out test was used to track training-induced changes in P-D parameters in response to 6-weeks of sprint or endurance training (chapter 7). EP & WEP were differently altered compared to CP and W′ following sprint training (CP 12 ± 9; EP -0 ± 9 % change; W′ -5 ± 25; WEP 11 ± 15 % change). The all-out test reliably tracked changes in CP and W′ following endurance training. In conclusion, the all-out test provides reliable EP and WEP values. Its validity is acceptable, but is perhaps affected by exercise training that is specific to the execution of the test. The W′ appears to be determined, to a large extent, by the relative size of the severe-intensity domain.

The IL-6 system is key in the development of chronic low-grade inflammation. It is known to be upregulated in response to acute exercise and lowered at rest after exercise training. IL-6 has both anti- and pro-inflammatory properties and moderation of this cytokine could alleviate chronic low-grade inflammation which is associated with obesity and Type 2 diabetes mellitus (T2DM). This thesis investigated the interplay between inflammation, glycaemic control and high intensity intermittent training (HIIT) - an exercise regimen that has been shown to yield many health benefits. There was a greater increase in IL-6 after an acute bout of HIIT than continuous moderate intensity exercise, where external work was matched (Chapter 4). Although sIL-6R and the IL-6/sIL-6R complex were both significantly increased after acute exercise there were no differences between HIIT and moderate intensity exercise. In response to 2 weeks HIIT there was a significant reduction in IL-6 and increase in IL-6R in adipose tissue in overweight and obese males (Chapter 5). It was also determined that IL-6R present in adipose tissue is at least partly composed of the membrane-bound IL-6R isoform (Chapter 6). Reductions in circulating sIL-6R, the IL-6/sIL-6R complex, MCP-1 and adiponectin, as well as a decrease in waist circumference and increase in peak oxygen uptake during exercise were also induced after 2 weeks HIIT (Chapter 5). Young adults with T2DM (< 40 y) displayed elevated levels of inflammatory proteins in comparison to lean controls, however there were no significant differences in comparison to obese controls (Chapter 7). In conclusion, the findings of this thesis demonstrate that acute and repeated bouts of HIIT have positive effects on the inflammatory profile in the circulation and adipose tissue, particularly in relation to the IL-6 system. It should be determined if HIIT is an achievable mode of exercise for patient populations, including T2DM patients, in order to downregulate the inflammatory profile.

Dance has attracted little scientific interest on the effects of physical fitness improvements on performance and injury severity, particularly with respect to contemporary dance. The main aims of the current work were: a) to observe the physical demands of dance performance; b) to develop a reliable dance-specific performance tool; c) to assess the association between selected physical fitness parameters and performance in contemporary dance by using a new reliable method (AC test); d) to assess selected physical fitness parameters in relation to injury severity in contemporary dance; e) to study the effects of increased fitness parameters on performance through a randomized controlled trial. A total of 50 performances, performed by 20 dancers, were monitored by using a portable accelerometers (SWA armbands) and heart rate monitors while 45 performances in DVDs were video analysed. Six dancers and two dance teachers were recruited to test a newly developed performance tool. A sample made of 41 dancers were recruited and assessed for aerobic fitness (DAFT), lower body muscular power (jump height test), upper body muscular endurance (press-ups test), flexibility (active and passive hip ROM), body composition (skinfolds), performance (n=17) and injury severity (n=16). In order to investigate the effects of the supplementary fitness training on performance, 24 of the total 41 dancers, were randomly assigned to either an intervention (n=12) or control (n=12) group. The intervention group undertook a specifically designed exercise-training programme (circuit and WBV training) lasting six weeks. Both groups were re-tested for physical fitness levels and performance at the end of the intervention period. Results revealed that performance intensities varied from light to moderate while these were observed with the use of pliés and jumps as well as lifting other dancers. Based on the seven most frequently used criteria by selected pre-professional contemporary dance institutions and companies, a novel performance tool (AC tool) was developed with an inter-rater reliability of r=0.96. There was a significant correlation between aesthetic competence (AC) scores and jump ability (r=0.55) and press-ups (r=0.55), respectively. Stepwise backward multiple regression analysis revealed that the best predictor of AC was press-ups (R2=0.30, p=0.03, 95% confidence intervals=0.11–1.34). Univariate analyses also revealed that the interaction of press-ups and jump ability improved the prediction power of AC (R2=0.44, p=0.004, 95% confidence intervals=0.009–0.04). Pearson’s correlation coefficients detected significant negative correlations between the mean score recorded for injury severity (expressed as TDO) and lower body muscular power (r=-0.66; p=0.014); backward regression analysis also revealed that, from all studied parameters, the strongest predictor of TDO was lower body muscular power (p=0.014). For the intervention group repeated measures ANOVA revealed significant increases (pre vs. post) in aerobic fitness (p<0.05), lower body muscular power (p<0.05), upper body muscular endurance (p<0.05) and performance (p<0.05). Linear regression analyses indicated that the only significant predictor of AC was aerobic capacity (F=7.641; p=0.03); the interaction of press-ups and aerobic capacity (F=6.297; p=0.036), and lower body muscular power with aerobic capacity (F=5.543; p=0.05) demonstrated an improved prediction power. These results show that the observed contemporary dance performance is an intermittent type of activity of moderate intensity. Given the reliability of the AC tool, it is concluded that upper body muscular endurance and jump ability best predict AC of contemporary dancers. Reduced lower body muscular power is associated with increased severity of injuries. Finally, supplementary exercise training significantly increases lower body muscular power, upper body muscular endurance and aerobic fitness, which in turn are beneficial to improve AC of contemporary dancers.

Background: Participation in physical activity (PA) is influenced by a multitude of factors. Traditionally, research has focused on several theoretical frameworks focusing on the individual ; however, they do not necessarily take into consideration other influencing factors such as the social environment or the physical or built environment. As such, a comprehensive socio-ecological model considering a multiplicity of factors is useful in explaining behaviour. Aims: To 1) assess the prevalence of the individual level correlates and their association with PA and walking; 2) assess the prevalence of environmental determinants and neighbourhood characteristics and the association between these and PA and walking behaviours; 3) explore within a comprehensive and socio-ecological approach, the contribution of the individual, social, and environmental factors in predicting PA and walking. Methods: The studies used in this thesis are national, random-digit dialling telephone-based surveys of a representative population sample within Canada. All research questions and procedures underwent ethics review at York University. The studies incorporated a two-stage probability selection process to select a survey respondent, and included a number of standard self-report measures across the data collection cycles. PA and all-domain walking were measured using the telephone-administered, short International Physical Activity Questionnaire, the neighbourhood environment was measured using an abbreviated version of the Neighbourhood Environment Walkability Scale (NEWS), and individual factors such as knowledge about amount of PA required for guidelines, beliefs about the benefits of PA, self-efficacy, intention, and initial behaviour changes. Walking for transport was measured through the Physical Activity Monitor and walking for recreation were measured through an adapted version of the Minnesota Leisure-Time PA questionnaire (for the 2007 collection only). Complex sampling methods were required to take into account stratification by province or territory within Canada. Complex samples cross-tabulation procedures were used to calculate the prevalence estimates of Canadians meeting the PA and walking guidelines and 95% confidence intervals. The relationship between factors predicting sufficient activity and sufficient walking were examined using complex samples logistic regression procedures that were reflect the sample design. This thesis explored associations and the relative strength of the factors as the independent measures predicting sufficient PA and sufficient walking as the dependent measures, using age, sex, and education as covariates for each of these models. Chapter Six expands this model by including walking for recreation and transportation, and examining sub-population groups. Results: Individual factors (e.g., self-efficacy, intention, and some trial behaviours) and social factors were associated with sufficient PA and certain types of walking. Relatively few environmental factors were associated with sufficient walking (all domain and domain-specific) or sufficient PA. The relationship between high density neighbourhoods and higher rates of walking (generally and specific), and the availability of supportive walking facilities with various modes of walking were evident. Proximity of many shops and the presence of sidewalks were associated with the highest quartile of walking for transport. A greater number of the individual factors predicted walking and PA compared to the environmental/neighbourhood factors, within the context of a full socio-ecological model. Findings differed when stratified by age and sex of respondents. Conclusions: The results suggest that individual factors may be more relevant for predicting activity and walking than environmental factors, or at least should be considered in their inter-relationship with environmental factors when developing environment-based interventions. Although the inter-relationship between individual factors, social factors and the built environment are important, understanding individual factors are critical for determining strategies and interventions to promote PA among certain populations with traditionally lower levels of activity. Findings suggest that within countries like Canada, with a relative abundance of supportive environments, more specific and detailed measures of the perceived and objective physical environment may be required in order to achieve sufficient variation.

Physical inactivity among young people is a public health concern. Markers of physical inactivity, such as low cardio-respiratory fitness (CRF) and obesity are adversely related to higher order cognitive functions, which underpin goal directed behaviour (i.e. cognitive control) and are implicated in academic achievement. Regular aerobic exercise can benefit cognitive control in children. However, it remains unknown whether daily physical activity behaviour is associated with cognitive control. Investigating this is important as targeting increments in daily moderate-to-vigorous physical activity (MVPA) may initially be a more realistic policy goal than developing aerobic exercise interventions. Nominal number of studies assessed this relationship using objective monitoring of physical activity (accelerometry), and yielded mixed results. None of the studies into objectively measured physical activity and cognitive function in young people controlled for CRF, which is posited to mediate the relationship between regular aerobic exercise and cognitive control. Likewise, other important confounders such as intelligence, have yet to be addressed in the literature. Moreover, it is unknown whether this relationship varies with age, as extant studies looked solely at younger adolescents. For example, meta-analytical findings (Fedewa & Ahn, 2011) suggest that children can benefit more cognitively from CRF and chronic aerobic exercise than adolescents as greater effect sizes have been observed for younger compared to older youngsters. Alternatively, chronic aerobic exercise may be specifically needed for cognitive benefits to emerge. However, none of the aerobic exercise interventions included objective assessments of baseline physical activity and few studies assessed the effects of chronic aerobic exercise interventions on multiple indices of cognitive control. This thesis aimed to address the limitations of previous research and to investigate: 1) the associations between objectively measured daily MVPA and cognitive control in older adolescents (study 1), and 2) in preadolescent children (study 2), while controlling for CRF, general intellectual ability and a number of important confounders (e.g. adiposity, attention-deficit hyperactivity disorder); 3) the relationship between daily MVPA and academic achievement (study 2); 4) the effects of chronic aerobic exercise intervention on cognitive control in children, while controlling for objectively measured daily MVPA and time sedentary at baseline (study 3). Methods: Study 1. A sample of 667 adolescents (Mage = 15.4, SD = .17, 55.5% girls) from the Avon Longitudinal Study of Parents and Children was included in the analyses. MVPA was measured with ActiGraph, GT1M accelerometer. CRF was assessed with sub-maximal cycle ergometer test and expressed as weight adjusted predicted physical work capacity at the heart rate of 170 beats per minute (PWC-170). Attentional control was measured with Stop Signal task. Study 2. A sample of 81 children (Mage = 8.64 years, SD = .57, 45.7 % girls) was included in the analyses. MVPA was objectively measured using the ActiGraph, wGT3X+ accelerometer. CRF was measured using a maximal graded exercise test on a treadmill. Inhibitory control was assessed with a modified Eriksen flanker task, working memory with Operation Span Task; and academic achievement with Kaufman Test of Educational Achievement. Study 3. 32 children (Mage = 8.64, SD = .58, 56.2% girls) were randomised into a physical activity intervention (FITKids2) or a waitlist control group. Changes in VO2max were measured using a maximal graded treadmill exercise test and changes in MVPA were objectively monitored for 7 days using the ActiGraph, wGT3X+ accelerometer. Behavioural measures of inhibition (reaction time, and accuracy) and working memory (accuracy) were taken using computerised laboratory tasks (modified Eriksen flanker task and Operation Span Task). Results: Study 1. MVPA was not significantly related to cognitive processing speed or variability of cognitive performance in hierarchical linear regression models. In simple regression models, CRF was negatively related to mean RT on the simple go condition (R2 = 2.6%, F(1, 308) = 8.28, p = .004). Study 2. No significant associations were noted between MVPA and either inhibition, working memory, or academic achievement. In contrast, CRF explained 4.7% of variance in accuracy interference (ΔR2 = .047, p = .045; β = -.22, t(78) = 2.03, p = .045, F(2, 78) = 4.95, p = .009). Study 3. FITKids2 physical activity intervention had a positive effect on the speed of responding during incongruent condition of flanker task (F(1, 30) = 4.69, p = .038, ηp2 = .13). A significant increase in BMI percentile was observed in the control (Z = 2.17, p = .03) but not in the intervention group (p = .53). Discussion: Study 1. Our results suggest that aerobic fitness, but not MVPA, was associated with cognitive processing speed under less cognitively demanding task conditions. The results thus indicate a potential global effect of aerobic fitness on cognitive functions in adolescents but this may differ depending on the specific task characteristics. Study 2. The results of this study suggest that CRF but not objectively measured MVPA was associated with better interference control in preadolescent children. Given the intermittent nature of children s daily MVPA, it is possible that aerobic exercise, which increases CRF is needed for cognitive benefits to emerge. Study 3. FITKids2 after-school physical activity intervention had a positive effect on children s inhibitory control, namely this cognitive function, which is closely related to academic achievement and future job and health outcomes. Thus, the results of this study convey a positive public health message, where promoting child s engagement in aerobic exercise can engender benefits to their cognitive function. Conclusions: The findings from this thesis can inform development of physical activity interventions to benefit cognitive functions in young people and contribute to the evidence base to inform future health and educational policies.

Au cours des années 1980, il y a été prouvé que l’étude de la variabilité de la fréquence cardiaque (VFC) permet d’estimer de façon non invasive l’activité du système nerveux autonome. Plus spécifiquement, de nombreux travaux démontrent que des enregistrements réguliers de la VFC peuvent rendre compte de la capacité d’adaptation d’un athlète à l’entraînement mais également de son état de fatigue. Bien que plusieurs auteurs suggèrent d’utiliser cet outil directement sur le terrain, il semblerait que l’absence de méthodologie commune et unifiée rende parfois difficile l’interprétation des résultats. Par conséquent, les travaux de recherche présentés au sein de ce manuscrit suivent avant tout une orientation méthodologique avec, néanmoins, une finalité pratique. Une première étude s’intéresse au ratio Basses fréquences/hautes fréquences (LF/HF) qui est communément utilisé comme marqueur de la fatigue. Nos résultats démontrent que chez les athlètes, ce ratio est avant tout modulé par la fréquence de respiration du sujet et que, contrairement à ce qui est couramment admis, une valeur supérieure à quatre ne traduit pas forcément un état de surentraînement. La seconde étude compare l’évolution quotidienne des différents marqueurs de VFC pendant 21 jours de suivi d’athlètes dans deux situations différentes : un enregistrement réalisé en respiration libre et un autre en respiration contrôlée. Nous avons constaté que les marqueurs RMSSD et SD1 suivent exactement les mêmes tendances quel que soit la méthode de respiration. A l’inverse, nos résultats démontrent une nouvelle fois que les indices fréquentiels sont avant tout modulés par la fréquence de respiration de l’individu. La troisième étude s’intéresse à une nouvelle méthode d’évaluation de la charge d’entraînement à l’aide de la VFC. Basée sur trois enregistrements qui intègrent à la fois les perturbations homéostatiques générées par la séance et la vitesse de réactivation parasympathique, la formule proposée permet de quantifier objectivement la charge d’entraînement dans des conditions de terrain. Les fortes interactions qui existent entre la VFC et l’entraînement nous encouragent à poursuivre notre démarche d’investigation pour utiliser cet outil dans le but d’individualiser et d’optimiser la planification d’entraînement des athlètes / During the 1980s, it was demonstrated that studying heart rate variability (HRV) makes it possible to estimate the activity of the autonomic nervous system noninvasively. More specifically, many works showed that regular recording of HRV can be used to monitor an athlete’s capacity to adapt to training and their fatigue. Although several authors have suggested using this tool directly in the field, it appears that the lack of a common and uniform methodology sometimes makes it difficult to interpret results. Therefore the research presented in this manuscript follows a methodological tendency with, nonetheless, a practical objective. The first study focuses on the Low Frequency/High Frequency (LF/HF) ratio commonly used as a fatigue indicator. Our results show that in athletes, this ratio is above all modulated by the subject’s respiratory rate and that, contrary to what is currently accepted, a value higher than four does not necessarily express a state of overtraining. The second study compares the daily evolution of different HRV markers over 21 days monitoring of athletes in two different situations: recording of spontaneous breathing and of controlled respiration. We observed that RMSSD and SD1 markers follow precisely the same trends whatever the breathing method. Conversely, our results show once again that rate indexes are above all modulated by an individual’s breathing frequency. The third study focuses on a new HRV-based method for evaluating training load. Based on three recordings that include both the homeostatic disturbances generated by the session and the speed of parasympathetic reactivation, the method proposed permits objectively quantifying training load under field conditions. The strong interactions existing between HRV and training encourage us to continue our investigative approach and use this tool to individualize and optimize athletes’ training programs

Despite clear recommendations on the minimal amount of physical activity for achieving health benefits and reducing risk of chronic disease, the majority of people in the Western world remain sedentary. As a 'lack of time' has been identified as one of the main barriers to becoming and remaining physically active, in the past decade research has focused on high-intensity interval training (HIT) as a time-efficient alternative to aerobic exercise. Although initial studies convincingly demonstrated equal or better health benefits with various HIT protocols compared to much larger volumes of aerobic exercise, these HIT protocols tend to be very strenuous and as such are unlikely to be adhered to by sedentary populations. Furthermore, most HIT protocols are not as time-efficient as sometimes claimed, with the total time per exercise session generally exceeding 20-30 minutes. This thesis aimed to characterise the effects of a novel reduced-exertion HIT (ReHIT) protocol, requiring a maximum of 2 x 20 s all-out sprint efforts in a 10 min training session, upon insulin sensitivity, aerobic capacity, glycogen utilisation and associated acute metabolic responses. The ReHIT exercise bouts were well tolerated by participants, but were associated with a substantial disturbance of physiological homeostasis including muscle glycogen degradation, lactate accumulation, excursions in plasma volume, post-exercise oxygen consumption, respiratory exchange ratio and heart rate, as well as a skeletal muscle signalling response through AMPK, and increases in skeletal muscle GLUT4 and PGC1α mRNA expression (Chapter 4 and 5). The combined training studies (n=49) provide some support for improvements in key disease biomarkers following ReHIT, with improvements in insulin sensitivity observed in men, and increased aerobic capacity observed in men and women (Chapter 7). These observations highlight a potential regulatory role for glycogen in exercise-induced adaptation. However, the mean improvements in insulin sensitivity in men were not consistent between the two training studies (Chapter 2 and 6), and there was a high level of variability observed between individuals (Chapter 6 and 7). Therefore, the impact of ReHIT on insulin sensitivity needs to be further explored in the context of a randomised controlled trial, and the mechanisms underpinning the large variability in adaptive response need to be characterised.

The purpose of the present thesis was driven by the limited existing evidence examining nutritional and physical activity (PA) profiles of older migrant women, and the importance of such studies for the planning and development of appropriate strategies to promote healthy ageing. This thesis adopted a mixed-methods approach to explore current dietary intake, nutrient status, and key factors influencing dietary factors (Chapter 3) of first generation migrant older women from diverse ethnic, socio-economic, and migration backgrounds (n=76). Chapter 4 sought to explore if the reported low energy and low nutrient intakes found in Chapter 3 were associated with frailty. Chapter 5 examined the association between objectively measured PA/ST and frailty, and identified key factors influencing PA amongst a sub-sample of the study sample (n=60). Given that diet and PA are potential mediators to promote healthy ageing in this population, Chapter 6 explored experiences of ageing and how these, in turn, shaped participants’ perceptions of ‘good’ old age as well as nutrition and physical activity behaviours. The present thesis provided an opportunity to better understand the dietary and PA profiles of first generation migrant older women and how they relate to frailty and ageing within the contemporary super-diverse UK context.

Isometric exercise training has been shown to bring about beneficial reductions in resting blood pressure, however the physiological mechanism responsible remain equivocal. It is currently unknown whether isometric exercise training-induced reductions in resting blood pressure are associated with improvements in vascular endothelial function and structure. The aim of this thesis was to investigate the effect of an 8-week isometric exercise training intervention on resting blood pressure, conduit artery vascular endothelial function, artery diameter and blood flow patterns at rest. Fourteen healthy young males (mean age: 23 ± 4 years; body mass: 80.7 ± 11.0kg; height: 178.8 ± 6.2cm) completed 8-weeks of isometric bilateral leg extension exercise training at high intensity (105.4% 2-min torquepeak). Three exercise sessions were performed each week and each session consisted of four 2-minute isometric muscular contractions each separated by a 3-minute recovery period. Resting blood pressure was measured using brachial artery oscillometric methods at pre, mid and post intervention. Brachial artery flow-mediated vasodilatation and resting artery diameter and blood flow were assessed at pre, week 2, mid, week 6 and post intervention using high-resolution duplex Doppler ultrasound. Total peripheral resistance and cardiac output were determined at pre and post intervention using high-resolution echocardiography. A generalised estimating equation analysis was used to estimate the effect of exercise versus non-exercise intervention over time on resting blood pressure, brachial artery flow-mediated vasodilatation, artery diameter and blood flow, total peripheral resistance and cardiac output. Isometric bilateral leg extension exercise training reduced resting systolic blood pressure (training: 117 vs. control: 121 mmHg) (P=0.002) and resting mean arterial pressure (training: 88 vs. control: 91 mmHg) (P=0.001) following 4 weeks of exercise training compared to the control condition. Brachial artery flowmediated vasodilatation was increased (mid training: 8.65 ± 1.02% vs. mid control: 6.38 ± 1.14%) (P=0.011). Superficial femoral artery diameter, antegrade blood flow and antegrade shear rate were increased (all P≤0.05), whilst superficial femoral retrograde shear rate was decreased (P=0.013) following 2 weeks of exercise training compared to the control condition. There were no significant condition by time interactions observed in resting blood pressure, vascular endothelial function, artery diameter or blood flow patterns following 8 weeks of exercise training (all P≥0.05). Cardiac output was not significantly different following 8 weeks of exercise training (P=0.148). Total peripheral resistance was increased following 8 weeks of exercise training compared to the non-exercising control condition (P=0.054). Isometric bilateral leg extension exercise training can effectively lower resting blood pressure and increase conduit artery endothelium-dependent vasodilatation in healthy young men after 4 weeks with a concomitant reduction in resting blood pressure. These beneficial adaptations were no longer evident from mid to post exercise training in healthy normotensive young men.