There is no information available in the scientific literature that documents a specific assessment protocol for analysing a soccer player’s maximal power capabilities. As soccer-associated muscular power has not previously been investigated, it is not known how important power is in elite soccer and, if it is, the physiological and genetic determinants of soccer-associated power remain unknown. Such information could be used to optimise soccer-specific talent identification and development strategies. With this in mind, the overriding aim of our thesis was to investigate the physiological and genetic factors underpinning powerful actions in elite youth soccer. When devising an assessment of soccer-associated muscular power, there needs be a detailed analysis of the specific actions performed during elite competitive match-play that can be described as powerful. The aims of our first experimental study (Chapter Three) were to compare the frequency and durations of powerful actions during competitive English Premier League [under 18 (U18) and under 21 (U21)] elite youth soccer matches using a novel soccer specific powerful action (SSPA) notational analysis coding system. We found that while elite soccer match-play requires players to perform powerful actions in multiple directions [68 horizontal accelerations (in the horizontal-forward or mediolateral directions), eight sprints, and six vertical jumps (three bilateral and three unilateral)], horizontal accelerations of short duration (< 1.5 s) from different starting speeds were the most dominant type of explosive action. This activity profile provides a strong rationale for devising a muscular power assessment protocol that evaluates the ability to produce maximal power in multiple directions, from a unilateral stance. Our data also suggests that such a protocol could provide a specific lower body power profile in elite soccer players (ESP). The aim of our second study (Chapter Four) was therefore, to determine whether countermovement jumps (CMJs) in different directions [CMJs: bilateral vertical (BV), unilateral vertical (UV), unilateral horizontal-forward (UH) and unilateral medial (UM)] assessed independent lower-limb power qualities, and if CMJ performance differed between ESP (representing an English Premier League Academy regularly at U18 and under U21 levels) and non-elite soccer players (NSP). We found that unilateral CMJs in different directions assessed independent peak vertical power (V-power) and resultant take-off velocity capabilities, and the UH CMJ required significantly greater bicep femoris electromyographic (EMG) activation in comparison all other CMJs. Moreover, in comparison to NSP, ESP achieved greater V-power during all CMJs (p≤0.032) except for BV (p=0.197), and also achieved greater UH CMJ projectile range (51.6 ± 15.4 vs. 40.4 ± 10.4 cm, p=0.009). Our results suggest that unilateral CMJs in different directions, but not the commonly used BV CMJ, are determinants of U18 and U21 elite soccer playing status and can be used by applied practitioners as independent assessments of soccer-associated muscular power. As the physiological determinants of performance are of use to the applied practitioner for informing talent identification criteria, and prescribing detailed training intervention strategies, the primary aims of the third and fourth studies were to investigate the neuromuscular (Chapter Five) and tendon (Chapter Six) determinants of unilateral CMJs oriented in different directions. Our data suggests that unilateral CMJ performance is associated with direction-specific neuromuscular and tendon properties in U18 and U21 ESP. While UV CMJ performance was related to the size (quadriceps femoris muscle volume and physiological cross sectional area), architecture (vastus lateralis pennation angle) and ability to activate (vastus lateralis EMG activation level) the knee extensor muscles, UH CMJ performance was related to the elongation and compliance properties of the patellar tendon, and was inversely correlated with vastus lateralis fascicle pennation angle. Our findings highlight the importance of targeting specific neuromuscular and tendon properties when assessing and developing muscular power performance in U18 and U21 ESP. Many physiological changes occur during puberty (Viru et al., 1999) and our findings in Chapters Four, Five and Six may only be applicable in U18 and U21 ESP. Therefore, in our fifth study (Chapter Seven) we aimed to investigate the importance of acceleration, sprint, horizontal-forward CMJ and vertical CMJ capabilities at different stages of maturation in elite youth soccer. Elite soccer players and CON were grouped using years from/to predicted peak height velocity (PHV, a measure of growth velocity and an indirect measure of pubertal phase) to determine maturation status (ESP: pre-PHV, n=100; mid-PHV, n=25; post-PHV, n=88; CON: pre-PHV, n=44; mid-PHV, n=15; post-PHV, n=54). By comparing performance of ESP and control participants (CON) matched for maturation status, we found that acceleration and sprint performance were associated with elite youth soccer at all stages of maturation, but maximal power (horizontal-forward and vertical jumping) capabilities may only be important for elite youth soccer at mid- and post-peak height velocity. Our data could imply that assessments of acceleration and sprint capabilities should be included in soccer talent identification protocols at all stages of maturation, but maximal power should only be included at mid- and post-PHV. The purpose of our sixth experimental study (Chapter 8) was to investigate if specific gene single nucleotide polymorphisms [SNPs: ACTN3 R577X (rs1815739), BDNF G > A (rs6265), COL5A1 C > T (rs12722), and COL2A1 C > T (rs2070739)] played a role in determining elite youth soccer player status, and speed and power capabilities, in ESP and CON at different stages of maturation. We found that ACTN3 R- and BDNF G-allele frequencies were more frequent in post-PHV compared to pre-PHV ESP. Moreover, while the COL2A1 CC genotype was associated with greater horizontal power and faster 20 m sprint performance, BDNF GG genotype appears to positively influence 20 m sprint performance during the pre-PHV period only. Overall, our findings illustrate that elite soccer may require different genetic profiles before and after maturation, and genetic screening could be included in talent identification criteria to help predict maximal power and sprint potential in ESP. In summary, we devised a muscular power assessment battery that measured independent power qualities and could discriminate between U18 and U21 ESP and NSP. Our subsequent analysis showed that the physiological factors underpinning unilateral CMJ performance were direction-specific, and UV and UH CMJ capabilities were underpinned by separate neuromuscular and tendon properties, and should be assessed and developed, independently in U18 and U21 ESP. We then recruited a larger cohort of ESP and CON, at different stages of maturation, and demonstrated that muscular power was important for elite soccer performance at mid and post-PHV, but not pre-PHV. Finally, we showed that genetic profiles of ESP differed between pre- and post-PHV, and that certain gene variants [COL2A1 C > T (rs2070739), BDNF G > A (rs6265)] were associated with specific power and speed capabilities in ESP. Overall, our studies provide novel information that could have significant implications on soccer-associated power related talent identification and training intervention strategies in elite youth soccer academies.

Dynamic loading profiles beneath the human foot during sideslope walking were determined and differences to level walking established. The contact area of the foot was measured, and the arch index derived from the footprint. Thirty healthy adults walked on a tillable walkway which had a polymer sensor pressure platform mounted at the mid-point. The sideways tilt could be adjusted in 2° increments from level to 8°. By walking in both directions on the sideslope, volunteers placed their right foot in either the upslope or downslope position. Loading profiles and contact areas were recorded for upslope and downslope foot placements at each angle of tilt. The characteristics of the electrically resistive polymer sensors were determined prior to the walking trials. The sensor output was non-linear, mean within-sensor variation =3% (maximum 8%), mean hysteresis -9% (maximum 13%), pressure threshold sensitivity =35 kPa, and mean between-sensor variation =8% (maximum 18%) over the surface of the platform. The dynamic behaviour was reliable to 26Hz. The sensor was found to be sensitive to shear. The impact of this characteristic was assessed by comparison with a similar platform incorporating capacitive transducers that were not shear sensitive. The polymer sensor system indicated increased pressures beneath the heel with upslope foot placement, and similar increases beneath the central metatarsals with downslope placement. These features were not apparent in the profiles returned by the second platform. For both platforms, however, the first metatarsal showed increased pressures with downslope placement but decreased pressures with upslope placement. In addition, the initial contact time and duration of loading for the first metatarsal altered significantly. The contact area of the foot changed systematically with sideslope walking, such that the arch index increased with upslope placement and decreased with downslope placement. This study demonstrated that the conventional approach of assessing level walking would fail to identify the increased foot pressures that occur on sideslopes. This may have crucial implications for ulceration risk assessment. The systematic changes in arch index and first metatarsal loading indicate that sideslope walking might be beneficial in revealing aspects of the mechanical behaviour of the human foot if combined with a simultaneous kinematic analysis. Potentially, the method offers a new approach to assessing the functional capacity of the foot for both clinical and research purposes.

Orientador: Angelina Zanesco / Banca: Luiz Osorio Silveira Leiria / Banca: Leandro Pereira de Moura / Banca: Fabiola Taufic Monica Iglesias / Banca: Gilberto de Nucci / Resumo: O sistema nervoso simpático desempenha importante papel no sistema cardiovascular e no metabolismo, sendo que os receptores adrenérgicos do subtipo β3 (β3 -AR) estão amplamente distribuídos em diferentes células, encontrando-se especialmente no tecido cardíaco, musculatura lisa e tecido adiposo. Esses receptores estão relacionados a diversas ações fisiológicas, como relaxamento da musculatura lisa vascular e não vascular, lipólise do tecido adiposo branco e termogênese do tecido adiposo marrom. Por outro lado, a importância dos β3 -AR no tecido adiposo perivascular (PVAT) e regulação do tono vascular não é conhecida. O mirabegron (YM-178) é um agonista β₃-AR seletivo, atualmente desenvolvido por Astellas Pharma Inc., e aprovado desde 2012 pelos EUA, para tratamento de bexiga hiperativa, considerando a ação dos receptores β₃-AR no relaxamento do músculo liso. Contudo não existe nenhum estudo envolvendo o mirabegron nos parâmetros cardiometabólicos plasmáticos e no metabolismo do tecido adiposo e em modelos de obesidade. Objetivos: Analisar os efeitos do tratamento de Mirabegron (Mira), um agonista β₃-AR seletivo, por duas semanas em parâmetros cardiometabólicos e reatividade vascular na presença ou ausência de PVAT de camundongos obesos. Métodos: Camundongos C57BL/6J foram divididos em grupos controle veículo (CTR), controle tratado com Mira (CTR+MIRA), obeso alimentado com dieta hiperlipídica (HFD 12 semanas) tratado com veículo (OB) e obeso tratado com Mira (OB+MIRA). Mira f... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Sympathetic nervous system plays an important role in the cardiovascular system and metabolism. In particular, the β3 subtype adrenergic receptors (β3-AR) are widely distributed in different cells, especially in cardiac tissue, smooth muscle and adipose tissue. These receptors are related to several physiological actions, such as vascular and non-vascular smooth muscle relaxation, lipolysis and thermogenesis. In addition, β3-AR participates in the increasing of the number of mitochondria at specific sites of white adipose tissue, called browning of white adipose tissue. Finally, it is not known whether these receptor subtypes may play a role in regulation of the perivascular adipose tissue (PVAT) vasomotricity. Despite these important actions involving these receptor population, studies involving selective β3-AR agonists on obesity state are scarce. Mirabegron (YM-178) is a selective β₃-AR agonist, currently developed by Astellas Pharma Inc. and approved since 2012 by the USA for overactive bladder treatment, considering the action of β₃-AR receptors on smooth muscle relaxation. Intrestingly, there is no study involving the effects of mirabegron on cardiometabolic parameters, adipose tissue metabolism in obesity models. Objectives: To examine the effects of Mirabegron (Mira) treatment, for two weeks on cardiometabolic parameters and vascular reactivity in the presence or in the absence of PVAT in obese mice. Methods: C57BL / 6J mice were divided into vehicle control (CTR), Mi... (Complete abstract click electronic access below) / Doutor

Fundamental movement skills (FMS) are a vital part of a child’s development, which allow them to advance on to more complex movements, resulting in them functioning successfully in their daily lives and when participating in sports and physical activity. Despite the importance of FMS, previous studies have routinely found children to have low competency levels. Further research on competency levels in this area is required, specifically among UK children, as data on FMS proficiency and FMS interventions is dominated by research from Australia and North America. As such, the aims of this thesis were to a) document the level of FMS competency of preschool children from a highly deprived area of Northwest England, b) determine the effectiveness of a six-week Active Play intervention on FMS competency among preschool children from a highly deprived area of Northwest England, c) examine the relationship between FMS competency, physical activity and weight status over a five-year period between preschool and late primary among children from a highly deprived area of Northwest England and finally, d) gain the thoughts and opinions of experts and practitioners in order to help inform the development of an appropriate intervention to increase the physical literacy of preschool children.

Within youth soccer high training and match loads warrant appropriate nutritional attention, although research assessing the nutritional intake and habits of youth soccer players is scarce. This thesis aimed to investigate habits and explore experiences of dietary intake methods in an English Premier League youth academy. Study one (Chapter 4) quantified the energy, macro and micronutrient intake of players from age groups under (U) 13 to U18 (7-day food diary, n = 59). Results showed players across all ages were in energy deficit, with low carbohydrate intake, and a large individual variability for micronutrient intake in comparison to current recommendations. However, under-reporting may have influenced these results. Study two (Chapter 5), a qualitative approach, explored nutritional habits (n = 15) with study one participants using one-on-one interviews. The U15 – U18s players consciously periodise their carbohydrate intake throughout the week; U18s stated this was to aid body composition. When discussing their participation in the previous food diary study, U18s expressed that a quicker, more user-friendly method would be desirable. The third study (Chapter 6), therefore, assessed the use of smartphone technology to record dietary intake. Fulltime youth soccer players (n = 22) recorded their dietary intake on a single training day, using a smartphone application and a photography method respectively compared to 24-hr recall. The 24-hr recall provided significantly higher energy and macronutrient intake in comparison to the smartphone methods. This data suggests smartphone technology was more effective in tandem with 24-hr recall. To conclude, youth soccer players are in dietary energy and carbohydrate deficit, with variable micronutrient intake when compared to current recommendations and traditional 24-hr recall is recommend if using smartphone technology. Further research for the accurate quantification of dietary intake and energy demands is required. Dietary advice provision for youth soccer to reach current nutritional recommendations is warranted.

Made available in DSpace on 2016-01-13T13:27:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-03-23. Added 1 bitstream(s) on 2016-01-13T13:32:21Z : No. of bitstreams: 1 000855826.pdf: 1700050 bytes, checksum: 3f9143bebac89d222f726563e8341f18 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Adicional à relevância do endotélio, o tecido adiposo perivascular (PVAT) desempenha importante papel no controle do sistema cardiovascular e endócrino-metabólico, é responsável por liberar uma grande variedade de substâncias que podem modular a vasomotricidade. O objetivo do presente estudo foi verificar o papel do tecido adiposo perivascular em aorta de ratos treinados e alimentados com dieta hiperlipídica. Ratos Wistar (290-320 g) foram divididos em: Sedentário (c-SD), Sedentário Dieta Hiperlipídica (dh-SD), Treinado (c-TR) e Treinado Dieta Hiperlipídica (dh-TR). Pelo período de dezesseis semanas os grupos c-SD e c-TR receberam ração balanceada e os grupos dh-SD e dh-TR receberam dieta hiperlipídica. Após a oitava semana, apenas os grupos treinados iniciaram o treinamento físico aeróbio (TR) em esteira, 5 dias/semana, 60 min por sessão (10 min a 40% da velocidade máxima, 40 min a 50-60% da velocidade máxima e 10 min a 40% da velocidade máxima) e 0% de inclinação, até o final do protocolo total. Curvas concentração-resposta à acetilcolina (ACh), nitroprussiato de sódio (SNP), fenilefrina (PHE) e serotonina (5-HT) foram obtidas em anéis de aorta torácica na ausência (PVAT-) e na presença (PVAT+) do tecido adiposo perivascular. As concentrações plasmáticas de glicose, colesterol total (CT), triglicerídeos (TG), insulina e leptina, foram avaliadas. Foram determinadas as expressões das proteínas: sintase endotelial do óxido nítrico (eNOS) na aorta e sintase induzível do óxido nítrico (iNOS) no PVAT. A dieta hiperlipídica promoveu maior ganho de peso corporal e gordura epididimal, bem como aumento nos valores de TG, insulina e leptina no grupo dh-SD comparado aos grupos c-SD, enquanto que o TR reduziu estes valores no grupo dh-TR. Respostas Relaxantes: a potência (pEC50) e a resposta máxima (EMAX) aos agentes ACh e SNP não foram alteradas em todos os grupos, tanto para PVAT- ou PVAT+. Respostas... / The importance of perivascular adipose tissue (PVAT) in vascular function has recently been recognized. The aim of this study was to evaluate the effects of perivascular adipose tissue in the aorta responsiveness from trained rats fed with high fat diet. Male Wistar (290-320 g) rats were divided into: Control sedentary (c-SD), High fat diet sedentary (dh-SD), Trained (c-TR) and High fat diet trained (dh-TR). For sixteen weeks c-SD and c-TR groups were fed with standard chow and dh-SD and dh-TR groups were fed with high fat diet. After eight weeks, c-TR and dh-TR groups initiated the aerobic exercise training on treadmill, 5 days/week, 60 min/session (10 min at 40% of maximum speed, 40 min at 50-60% of maximum speed, and 10 min at 40% of maximum speed) and 0% grade until the end of the protocol. Concentration-response curves to acetylcholine (ACh), sodium nitroprusside (SNP), phenylephrine (PHE) and serotonin (5-HT) were obtained in thoracic aorta without (PVAT-) or with (PVAT +) the PVAT. The concentrations of glucose, total cholesterol (CT), triglycerides (TG), insulin and leptin were evaluated. The protein expressions of endotelial nitric oxide synthase (eNOS) in aorta and inducible nitric oxide synthase (iNOS) in PVAT were determined. The high fat diet increased the body weight gain, epididymal fat pad, TG, insulin and leptin in dh-SD group compared to c-SD, whereas TR reduced these values in dh-TR group. Relaxing response: The PVAT+ rings did not modify the potency (pEC50) and the maximal response (EMAX) to ACh and SNP agents. Contractile responses: The PVAT reduced the EMAX to PHE (mN/mm) in all groups: c-SD (PVAT+: 3.5±0.4 and PVAT-: 6.8±0.5), c-TR (PVAT+: 4.7±0.8 and PVAT-: 7.9±1.4), dh-SD (PVAT+: 2.1±0.2 and PVAT-: 6.1±0.6) and dh-TR (PVAT+: 2.5±0.4 and PVAT-: 5.8±0.5), in a similar magnitude. We also found an anticontractile effect to 5-HT: c-SD (PVAT+: 7.0±0.9 and PVAT-: 9.7±1.3), c-TR ...

Made available in DSpace on 2016-01-13T13:27:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-04-15. Added 1 bitstream(s) on 2016-01-13T13:33:17Z : No. of bitstreams: 1 000855932.pdf: 2887838 bytes, checksum: 7b208c55623196e4338cefb07a6c175c (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A obesidade é uma doença que vem crescendo de forma alarmante e está associada com resistência à insulina (RI) e desenvolvimento de doenças crônicas não transmissíveis como as cardiovasculares, alguns tipos de câncer e o diabetes mellitus do tipo 2. A RI pode ser instalada tanto a nível muscular bem como hepático, colaborando fortemente para alteração inicialmente na glicemia pós-prandial e mais tardiamente na glicemia de jejum. Por outro lado, a prática regular de exercício físico é capaz de melhorar à ação da insulina tanto no músculo esquelético aumentado a captação de glicose, quanto no fígado reduzindo a formação de nova glicose (gliconeogênese). Entretanto, os efeitos do exercício físico sobre a via molecular da insulina não são totalmente conhecidos. Recentemente uma nova proteína foi classificada como mediadora da sinalização da insulina por potencializar seus efeitos, essa proteína é a Rho-kinase (Rock) que atua em tecidos periféricos (músculo esquelético, fígado e adiposo) e também, no hipotálamo, contribuindo com até 50% da ação insulina no meio intracelular. Ao contrário, animais experimentais que tiveram a deleção ou inibição da Rock se tornaram resistentes à insulina. Visto isso, estudos sobre esta molécula fazem-se necessários para melhor entendimento dessa complexa sinalização. Como ainda nenhum estudo havia sido realizado objetivando avaliar se os efeitos benéficos do exercício físico sobre a via de sinalização da insulina é em decorrência ou não da participação da proteína Rock, o presente estudo teve como objetivo investigar o papel do exercício físico aeróbio na regulação da proteína Rock e os efeitos sobre a sinalização da insulina em músculo esquelético e fígado de camundongos obesos. Para este desfecho, este estudo foi dividido em duas etapas, sendo a primeira etapa desenvolvida na escola de medicina de Harvard e a segunda no Brasil: Etapa 1- na / FAPESP: 13/00554-6

Made available in DSpace on 2016-01-13T13:27:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-08-15. Added 1 bitstream(s) on 2016-01-13T13:33:26Z : No. of bitstreams: 1 000855970.pdf: 2070850 bytes, checksum: c7dff43f36eab281f23e98b357ba20da (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / No contexto da saúde pública nacional, pouco se conhece sobre as particularidades do tratamento com estatinas e os efeitos musculares da associação de exercícios físicos moderados ao tratamento crônico, bem como seus mecanismos. Assim, os objetivos deste estudo foram avaliar as ações do tratamento medicamentoso com estatinas na saúde pública e os efeitos da terapêutica medicamentosa isolada e em associação a um programa de exercícios físicos moderados no tecido muscular. Para tanto, foram obtidas informações sobre o estado de saúde e o tratamento medicamentoso dos prontuários médicos (n=62) de mulheres atendidas em uma unidade básica de saúde (UBS). Posteriormente, as pacientes foram avaliadas quanto ao nível sócio econômico, presença de comorbidades, medicamentos em uso, nível de atividade física, autorrelato de dor muscular, aderência ao tratamento e composição corporal (n=72). Nas etapas subsequentes, foram incluídas somente as pacientes sedentárias e na menopausa (n=61); destas, uma parcela foi submetida à biópsia muscular (n=21) e aos testes de função muscular (n=17). Para exposição ao sedentarismo (n=12) ou à prática de exercício físico (n=13) aeróbio (50 minutos) e resistido (25 minutos), três vezes por semana, durante vinte semanas, foram incluídas as pacientes que não apresentaram fatores de risco para lesão muscular por estatinas. Ao final da intervenção, todas as avaliações foram reaplicadas. Verificou-se que a conduta médica de modificar dose (48,4%) e/ou o tipo (25,4%) de estatinas objetivou adequação do perfil lipídico sem lesar a musculatura. A não aderência das pacientes à prescrição médica foi de 15,5%, ocorrendo prioritariamente em mulheres jovens (p=0,057), com menor frequência de comorbidades (p=0,011) e baixo consumo de medicamentos (p=0,001). As biópsias musculares indicaram padrões de alterações metabólicas (MET) e neurogênicas (NEU) isoladas ou... / In the Brazilian public health context, little is known about the particularities of statin treatment, and the mechanisms implied in skeletal muscle effects due to the association of long-term treatment and moderate physical activity. Thus, the aims of this study were to evaluate the actions for statin treatment in primary care, so as to assess muscle skeletal effects of statin treatment alone and in association with a moderate physical activity program developed in basic healthcare units. So, information collection in clinical reports was conduct in order to obtain health state and medication treatments of female patients (n=62) assisted in a basic healthcare unit (BHU). Identified patients were evaluated for socioeconomic state, comorbidities, medications in use, physical activity practice, self-reported muscle pain, adherence to medication treatment and body composition (n=72). In the following steps, only sedentary and menopause patients were included (n=61); of them, a sample was submitted to muscle biopsies (n=21) and test of muscle fucntion (n=17). For sedentary state (n=12) or aerobic (50 minutes) and resistance (25 minutes) physical exercise practice (n=13), three times per week, during 20 weeks, only free-statin predisposing muscle injury factors patients were included. In the end of intervention period, all parameters were revaluated. Medical attitude of modifying statin doses (48.4%) and/or types (25.4%) aimed lipid profile adequacy without muscle injuries. The frequency of non-adherent patients were 15.5% and mainly occurred in younger females (p=0.057), with less morbidities (p=0.011) and medication consumption (p=0.001). Muscle biopsies indicated patterns of metabolic (MET) and neurogenic (NEU) injuries, that occurred alone or associated, and had influenced the time to reach peak force (NEU > MET+NEU, p=0.01) and the percentage of force loss (NEU < MET+NEU, p=0.01). Adding moderate physical exercise to regular treatment ...

Ramadan requires individuals to abstain from food and fluid intake between sunrise and sunset; physiological considerations predict that poorer mood, physical performance and mental performance will result. In addition, any difficulties will be worsened because preparations for fasting and recovery from it often mean that nocturnal sleep is decreased in length, and this independently affects mood and performance. Previous field studies have indicated that some of these predictions are borne out in practice; in the first study of the present thesis, a field study performed in Libya, these predictions were tested further by adding more physiological measurements and tests of performance. Findings indicated that Ramadan was associated with negative effects upon a wide range of variables, including rising urine daytime osmolality (indicative of progressive dehydration), subjective estimates of amounts of activities actually performed and those wished to be done (indicating less activity in the daytime), and metabolic and subjective responses to a short bout of exercise (increased effort required and metabolism tending towards fat rather than glucose catabolism). Because of the difficulties of performing a battery of tasks in a field study, two laboratory-based experiments were then performed, the second differing from the first in studying a greater range of variables and more time-points during the daytime. These two studies also differed from the situation in Ramadan in that non-Muslim students were volunteers and fasting was performed for only one day. Many of the changes previously found in Ramadan were duplicated in this work, so justifying the use of laboratory experiments lasting one day and using non-Muslim subjects as a model for some of the problems present in Ramadan. However, it was also found that preparations before the fast were often less marked than was the case with Muslims in Ramadan, a difference that can be attributed to subjects' lack of experience of fasting as well as the amount of time spent fasting. A difficulty of interpretation in all these studies was that changes could be due to fasting and/or the length of sleep, which tends to decrease. These two factors were separated in the final experiment, an intervention study performed in the laboratory. This study compared effects of different durations of fasting (4, 8 or 16 h) upon a wide variety of measures (including subjective and objective assessments of performance, dehydration and responses to a short bout of exercise) - but with an unchanged amount of nocturnal sleep and daytime naps not allowed. Many of the negative effects observed in previous studies were present in this experiment also. These findings indicate that fasting was responsible for much of the change previously observed, though some effect of sleep loss, particularly if occurring on successive days (as would occur in Ramadan) cannot be excluded. One finding common to all studies was that tests of performance that had shown variations due to the combination of circadian influences, time awake and sleep loss in other experiments (including grip strength, the Stroop test and accuracy at throwing darts) seemed little affected. Possible reasons for these negative findings are discussed, together with further experiments to separate out effects of sleep loss and fasting, and the role of subjects' experience in studies of fasting. In addition, more detailed studies to investigate changes in sleep and the type and level of physical activities when fasting are proposed.

Cardiovascular disease is one of the largest killers in the UK representing 30% of all global deaths. The underlying processes of the disease are thought to begin in childhood. Whilst traditional risk factors of CV disease (e.g. hypertension, hyperlipidemia, obesity, smoking, stress and sedentary lifestyles) are becoming increasingly prevalent within the younger generation there remains the need for the establishment of earlier or "pre-clinical" markers of future CV disease risk or current atherosclerotic load such as left ventricular (LV) mass, diastolic function and carotid intima-media thickness( cIMT). Further, assessing the association of these markers to other risk factors and then determining the impact of physical activity (PA) interventions is warranted. Initially we assessed the impact of body composition, PA and cardiorespiratory (CR) fitness upon left ventricular LV mass, carotid-intima media thickness (cIMT) and LV diastolic function in 218 9-11 year old primary schoolchildren. Pubertal status was assessed through a maturity offset calculation. LV mass, cIMT, and LV diastolic function were assessed via ultrasound. Body mass index was assessed via anthropometry whilst fat mass [FM] and lean mass [LM] were determined via dual X-ray absorptiometry. Average 3-day PA was recorded via a uni-axial accelerometer and CR (VO₂peak) was determined from a graded treadmill test. Relationships were analysed using bivariate correlations and forced entry multiple regression. All children were classified as being below their peak height velocity. Together LM, FM, sex and moderate to vigorous (MV)PA accounted for 59% of the variance in LV mass with LM being the most important predictor (P<0.005). Sex, LM, FM and VO₂peak explained only 19% variance in cIMT and just 9% of the variance in LV diastolic function was accounted for by LM, FM blood pressure and sex. Data for MVPA had no significant relationship to any cardiovascular (CV) variables although was negatively correlated with FM. The strong association between LV mass and body composition likely represents normal growth. The limited shared variance between predictor variables and cIMT and LV diastolic function suggests that those pre-peak height velocity children in the current cohort who were overweight, inactive and unfit were not yet at an increased CV disease risk. Thus there is a window of opportunity for intervention programmes to be implemented that reduce CV disease risk before adolescence and adulthood. Following this, an exploratory trial was conducted to introduce the use of PA interventions in pre-pubertal children. Sixty-one 10-11 year old Liverpool primary school children volunteered and were randomly assigned by school to a STEX programme (2 x 60 min sessions per week at a heart rate of ~145 beats min⁻¹), a PASS programme (weekly physical activity tasks and pedometer challenges) and a control (CON; no intervention). Pre-clinical CV measures and body composition were measured before and after the 9-week intervention period. The primary outcome variable was cIMT, with LV mass, LV diastolic function, and body composition defined as secondary outcomes. Delta (Δ) scores were analysed by ANCOVA, with baseline scores as the covariate. For the primary outcome, the probability that the population effect of the intervention is at least as great as the pre-specified minimum clinically importance difference (MCID) was estimated, to evaluate clinical relevance. All participants met 75% compliance criteria for STEX and PASS. The effect of the STEX intervention (compared with CON) was a mean benefit of -0.018mm for average maximum cIMT (90% CI, -0.039 to 0.002mm), and -0.016mm for average mean cIMT (90 % CI, -0.040 to 0.008mm). The probability (% chances) that the true population effect of the STEX intervention would be clinically beneficial was 79% for average maximum and 71% for average mean cIMT. The PASS intervention did not result in clinically important effects, and no other substantial changes were observed for the secondary outcome variables. The relatively high probability of clinically beneficial effects of the STEX intervention suggests that a larger, "definitive" randomised trial with longer follow-up is warranted to define the effectiveness of the intervention more precisely. As a consequence the longer PA intervention study observed 152 children aged 9 to 10 years over 12 months. All of the echocardiographic, body composition, CR fitness and PA variables mentioned were assessed as previously discussed. Children were randomly assigned by school to an intervention group. Control (no intervention), PASS (as before except delivered during school hours to enhance compliance), high intensity physical activity (the same as STEX but renamed due to the addition of another structured exercise group) or fundamental movement skill ([FMS] 2x 60 min sessions per week of skill based activities). These interventions took place over a year period with participants being assessed at baseline, approximately mid-way through and post-test (52 weeks). Initial factorial ANOVA analysis comparing all 3 intervention groups and a control group before, during and after the 12 month intervention period, found limited statistically significant evidence for a positive impact of PA interventions compared to controls in pre-pubertal children. However, after adjusting for confounding variables in an ANCOVA analysis some sporadic benefits of PA interventions on CV variables were uncovered. An increase in LV mass over 12 months, after adjustment, was lower in the HIPA group compared to CON group (11.5 g; 90% CI, 2.0 to 21.0 g). This change was also lower in the FMS group compared to CON group (13.8 g; 90% CI, 4.6 to 23.1 g). The ANCOVA adjusted change scores for both mean and max cIMT were less in the intervention groups compared to CON group but only in the PASS group were these differences significant (P<0.05). PASS increased its mean cIMT (-0.014mm less than control (90% CI, -0.002 to -0.030)). Somewhat surprisingly the intervention programmes had no positive effect on CR fitness (indeed this decreased), PA measures and/or body composition over and above changes observed due to growth. This thesis has provided a unique insight into the 'pre-clinical' CV disease risk factors in pre-pubertal children and the impact of differing PA activity interventions with this group. Interestingly the research has shown that within this population overweight/obese, inactive low CR fit individuals are generally not at a higher CV disease risk than their aged matched 'healthier' counterparts. When PA interventions are introduced in the short term positive changes in cIMT were seen, however, this is not reciprocated in longer PA interventions possibly due to a larger maturation effect over 12 months. Interestingly year long interventions provide some attenuation of growth-related changes in CV disease risk factors but these changes are generally small and sporadic. It is suggested that further research over a longer period of time with more 'at risk' populations is needed. The PA interventions adopted achieved high attendance and compliance records and thus may be transferable out of the research process. It is interesting to also speculate that future research may not need to administer high impact activity, as previously thought, as some positive data was obtained in more general lifestyle interventions involving more knowledge transfer.