Uma sessão de exercício aeróbio provoca queda da pressão arterial (PA) e aumento da freqüência cardíaca (FC) pós-exercício. Diversos fatores, como a massa muscular, a intensidade e o gasto energético total do exercício podem influenciar esta resposta. Este estudo verificou as respostas pós-exercício da PA, da FC e de seus mecanismos, avaliando a influência dos fatores citados. Vinte e quatro jovens submeteram-se a quatro sessões: controle(C); exercício com um membro inferior (mmii) em 50% do VO2pico(E1); exercício com dois mmii em 50% do VO2pico (E2); e exercício com dois mmii com a mesma potência de E1(E2/1). As PA sistólica (PAS), média (PAM) e diastólica (PAD), o débito cardíaco (DC), a resistência vascular periférica (RVP), o volume sistólico (VS), a FC e a modulação autonômica cardíaca foram medidos. Após o exercício, a PAS e o DC diminuíram e a RVP aumentou em E2. A PAD e PAM não se alteraram. A FC aumentou e o VS e o componente de alta freqüência da variabilidade da FC diminuíram em E1 e E2 (maior em E2). Concluindo: o exercício aeróbio promove hipotensão pós-exercício, devido à queda do DC pela redução do VS. O gasto energético total do exercício é o principal determinante desta resposta. A FC permanece elevada pós-exercício devido ao retardo da reativação vagal. A intensidade e o gasto energético do exercício são os principais determinantes desta resposta / A single bout of aerobic exercise reduces blood pressure (BP) and increases heart rate (HR) during the recovery period. Many factors, such as exercise intensity, muscle mass and total energy expenditure might influence this response. This study verified post-exercise responses of BP, HR and their mechanisms, evaluating the influence of previous factors. Twenty-four subjects underwent four sessions: control (C); exercise with one leg at 50% of VO2peak (E1); exercise with two legs at 50% of VO2peak (E2); and exercise with two legs and the same workload employed in E1 (E2/1). Systolic, mean, and diastolic BPs (SBP, MBP, DBP), systemic vascular resistance (SVR), cardiac output (CO), stroke volume (SV), HR, and cardiac autonomic modulations were measured before and after interventions. After exercise, SBP and CO decreased, while SVR increased in E2. DBP and MBP did not change. HR increased, while SV and the high frequency band of HR variability decreased in E1 and E2 (more in E2). In conclusion: aerobic exercise produced post-exercise hypotension by a decrease in CO, via a decrease in SV. This response is determined by the exercise total energy expenditure. HR is elevated after exercise due to a delay in the restoration of vagal activity to the heart. Exercise intensity and total energy expenditure influence this response. Key-words: aerobic exercise, muscle mass, total energy expenditure, relative intensity, blood pressure, heart rate, autonomic modulation

Introdução: A síndrome do intestino curto (SIC) representa um estado clínico de má absorção grave, e a gestão dietética de pacientes com SIC é extremamente desafiadora. Uma vez que o grau de desnutrição é frequentemente considerável, a intervenção dietética bem sucedida depende da estimativa mais exata possível das necessidades energéticas para prever as metas da terapia nutricional. Objetivo: Quantificar o gasto energético total (GET) em pacientes com SIC pelo método da água duplamente marcada (ADM). Materiais e Métodos: Neste estudo observacional, o GET foi mensurado pelo método da água duplamente marcada em 22 voluntários, 11 com SIC e 11 controles pareados por sexo, idade e IMC (grupo Controle). O GET foi estimado pela equação de Escott-Stump e a partir de acelerômetro, e foi comparado com o GET determinado pela ADM. O gasto energético em repouso (GER) foi mensurado por calorimetria indireta (CI) e comparado com o GER estimado pela equação de Harris e Benedict. O acelerômetro também foi utilizado para estabelecer o nível de atividade física. Resultados: Os participantes tinham idade (média ± DP) de 53 ± 8 anos. O GET medido por ADM foi significativamente menor no grupo SIC comparado ao grupo Controle (p < 0,01); no entanto, o GET estimado não diferiu significativamente entre os grupos. O GET medido foi significativamente maior do que o GET estimado por fórmula no grupo SIC, (respectivamente 1875 ± 276 e 1517 ± 175 kcal/dia, p < 0,01), assim como para o grupo Controle (2393 ± 445 e 1532 ± 178 kcal/dia, p < 0,01). No entanto, o GET medido foi significativamente menor do que o GET predito a partir do acelerômetro no grupo SIC (2075 ± 298 kcal/dia, p = 0,02), e não diferiu significativamente no grupo Controle (2207 ± 355 kcal/dia, p = 0,21). Não foram verificadas diferenças significantes entre o GER medido e predito para ambos, e entre os grupos. Conclusão: O GET medido em pacientes com SIC foi significativamente maior do que o GET estimado por fórmula, e foi menor quando comparado com os valores dos sujeitos controles. No entanto, o GET estimado a partir do acelerômetro, superestima o GET medido por ADM. As fórmulas atualmente utilizadas na prática clínica parecem subestimar as necessidades de energia de pacientes com SIC. Desta forma, adaptações da estimativa atual, aumentando as prescrições de ingestão energética nestes pacientes parecem ser adequadas para apoiar as necessidades diárias de energia e evitar a subnutrição. / Background: Short bowel syndrome (SBS) is a serious malabsorption disorder, and dietetic management of SBS patients is extremely challenging. Once the degree of undernutrition has been assessed, successful dietary intervention depends on the most accurate estimation and provision of energy needs to provide nutritional therapy goals. Objective: To quantify total energy expenditure (TEE) in SBS patients using the doubly labeled water (DLW) method. Design: In this observational study, TEE was measured by the DLW method in 22 participants, 11 with SBS and 11 gender-age-and BMI-matched controls (Control group). Predicted energy requirements were determined using the Escott-Stump equation and by using and accelerometer, and they were compared with TEE determined with DLW. Resting energy expenditure (REE) was measured using indirect calorimetry and compared with predict REE using the Harris and Benedict equation. The accelerometer was also used to determine physical activity level. Results: Participants were aged (mean ± SD) 53 ± 8 years. Measured TEE was significantly lower in the SBS group compared to the Control group (p < 0.01); however, predicted TEE did not differ significantly between the groups. Measured TEE was significantly higher than predicted TEE for the SBS group, (1875 ± 276 and 1517 ± 175 kcal/d, p < 0.01) and also for the Control group (2393 ± 445 and 1532 ± 178 kcal/d, p < 0.01) when determined by formula. However, measured TEE was significantly lower than predicted TEE (2075 ± 298 kcal/d, p = 0.02) for the SBS group, and did not differ for the Control group (2207 ± 355 kcal/d, p = 0.21) when determined by accelerometer. No significant differences were seen between measured and predicted REE both within and between groups. Conclusion: Measured TEE in SBS patients was significantly higher than predicted using standard equations, but also lower than values for age, BMI and gender-matched non-SBS controls. However, predicted TEE using accelerometer overestimated the measured TEE. Currently-used formulas in clinical practice appear to underestimate energy requirements of SBS patients. Therefore, adjustments to the current estimation, increasing the energy intake requirements in these patients appear to be adequate to support the daily energy requirements and avoid undernutrition.

Introduction Optimal nutrition is vital in the management of infants born preterm. Dietary fat in infancy is fundamental for the provision of energy for growth and development. Essential fatty acids, specifically Long Chain Polyunsaturated Fatty Acids (LC-PUFAs) such as docosahexaenoic acid (DHA), have been under investigation by several international research groups in the past decade. Essential fatty acids are critical in neurodevelopment as DHA is found in high proportions in structural lipids of cell membranes, particularly in the central nervous system (CNS). The accumulation of essential fatty acids and particularly DHA in the brain and retina occurs most rapidly during the perinatal period, therefore preterm infants are of particular concern (Singer, 2001). Current scientific consensus is that the optimum growth rate for preterm infants is equal to the in utero growth rate throughout the last trimester, however, failure to achieve the optimum intrauterine growth rate is common in preterm infants (Olhager and Forsum, 2003). Preterm infants require large amounts of energy and nutrients with which many infants are not provided or are not able to absorb, due to immature gastrointestinal and metabolic systems and other medical complications (Olhager and Forsum, 2003). There are a number of unresolved issues regarding optimal growth rate and total energy requirements (ER) for preterm infants. Hypotheses/Objectives This study is a “side study” to a double blind randomised controlled trial (RCT) of DHA supplementation in preterm infants. The hypothesis of this “side study” is that increased DHA during the neonatal period would increase total energy expenditure (TEE) and improve neurodevelopmental outcome. Specifically, at term postconceptual age (PCA) it was hypothesised that preterm infants receiving higher intake of DHA would have higher TEE’s due to the acceleration in brain maturation. Also, it was hypothesised that preterm infants receiving high levels of DHA would have TEE’s equivalent to term born infants due to their same brain maturation status. Other hypothesised effects of DHA supplementation include an accelerated maturation of the visual cortical pathways, and accelerated white matter (WM) tract development aiding in brain maturation. The first objective of this study was to measure TEE and ER in very preterm infants when they reached an age of 31-33 weeks post conceptional age (PCA). The effects of DHA supplementation on TEE, at simulated in utero levels, in very preterm infants (born < 33 weeks PCA), when assessed at term equivalent (40 weeks PCA) were studied. Another objective was to compare WM brain tissue volume at term PCA between two preterm groups and then with the term born infants. Visual latency was also compared between the two preterm infant groups and then with the term born infants. Methods TEE was measured using the doubly labelled water (DLW) method which is based on the differential elimination of 2H (deuterium) and 18O from the body subsequent to a loading dose of these isotopes. TEE was measured at the preterm age between 31-33 weeks PCA and again at term PCA. TEE measurements are made at term PCA in a term born control group. Brain assessment was by Magnetic Resonance Imaging and (MRI) and Visual Evoked Potential (VEP). Magnetic resonance imaging quantitatively measured brain volumes and WM. Visual evoked potential would provide information on visual latency and amplitude. Results The cohort consisted of 38 infants. The TEE of the very preterm infant group was measured at 31-33 weeks PCA. The mean (±standard deviation) (SD) TEE was calculated at 80(±27) kcal/kg/d, and using data in the literature for foetal energy accretion of 28kcal/kg/d, the mean ER was calculated to be 108(±27) kcal/kg/d. At term PCA TEE was calculated for the preterm DHA supplemented group to be 56(±19) kcal/kg/d and for the non-DHA supplemented group 70(±39) kcal/kg/d. These measurements were not statistically different. Flash VEP conducted on preterm given different amounts of DHA tested at term PCA found no statistically different measurements. When combining these results and comparing them to measurements of term born infants at term PCA, the right eye measurements showed that preterm infants had statistically greater latencies than term infants. When combining the left and right eye measurements the latencies no statistical significance was found. Amplitude was also not statistically significant between the groups. MRI measures at term PCA were not statistically different DHA supplemented and the non-DHA supplemented preterm infant group. When the preterm infant cohort was combined and compared to the term born infant group, the results showed that preterm infants imaged at term PCA had reduced WM development in a number of frontal lobe projections, and anterior and posterior commissarial pathways of the corpus callosum and corona radiata. Discussion The TEE and ER measurements in this study represent the largest preterm infant cohort to date. The ER values reported here are of value in allowing the calculation of appropriate feeding and nutritional strategies for preterm infants. Although no differences in TEE between the DHA and non DHA supplemented groups were found this may have been due to the small sample size. With regard to the latency outcomes, it can be speculated that if measurements were conducted at a later PCA the correlations may have been stronger and significant. Several other factors may have also affected the results, including alertness of the infant at the time of testing, thickness of the cranium, and other health factors could not be controlled for. This study contains the youngest cohort to be compared via Flash VEP. The MRI data did not find significant differences in brain volume and WM between the DHA supplemented and the non-DHA supplemented groups. The infant CNS is rapidly developing and there are multiple environmental factors which may have affected outcomes. The data did however find differences in WM development between the preterm and term infants. The reduced WM development found in the preterm infants compared to term born infants may provide some explanation for the correlation between preterm birth and poorer cognitive and functional outcomes. Larger studies which extend beyond the first months of life are recommended in order to investigate the long-term relationships between DHA supplementation, TEE and brain maturation.

La croissance de la consommation par les villes de ressources naturelles est un facteur déterminant dans l’altération de la biosphère. Pour comprendre le processus du changement du rapport entre la ville et la biosphère, transition socioécologique dans le cas particulier de la ville, nous avons caractérisé la ville comme étant tributaire de la ressource externe en termes matériel et écologique. On s'intéresse dans ce travail à la relation entre la demande en énergie de la ville, l'évolution du système d'approvisionnement urbain et extra urbain en énergie, et le bassin d'approvisionnement en ressource énergétique avec le cas de l'agglomération parisienne. Pour ce faire, nous avons d'une part tenté d'évaluer la pression environnementale effectuée pour la consommation énergétique urbaine, métabolisme urbain, en utilisant la méthode d'analyse de flux d'énergie et de matière (AFME). L'AFME s'intéresse à mesurer le métabolisme d'une société et inclut par conséquent la consommation énergétique technique (pour le chauffage, le transport, l'industrie) ainsi que l'alimentation humaine et animale consommée dans la ville. La consommation énergétique urbaine est évaluée par la demande énergétique totale (DET), indicateur de pression environnementale, dans le but de mesurer la consommation d'énergie primaire en amont pour l'approvisionnement en énergie finale du territoire. On essaie ensuite de mettre en parallèle l'évolution de la DET pour l'énergie technique et l'évolution du rayon d'approvisionnement de cette dernière au fur et à mesure de la croissance urbaine. / Increasing urban natural resource consumption and particularly fossil energy consumption is one of the important factors of global environment alteration. To understand the socioecological transition process for the city, we characterize it as a natural resource dependent system in material and ecological terms. Cities mobilize a technical system to draw the external natural resource. Therefore, externality is a fundamental character of urban metabolism. We focus in this work on the relationship between the energy demand of the city, the evolution of the urban and extraurban energy supply system, and the energy resource supply area of Paris. We used energy and material flow analysis (MEFA) to evaluate environmental pressure driven by city's energy consumption, urban metabolism. MEFA aims to evaluate social metabolism, therefore energy demand including both the energy for technical system and bioenergy for food and forage provision for a society. Particularly, total energy requirement (TER) refers ta primary energy consumption, an indicator to evaluate the environmental pressure. Furthermore, we try to view the energy demand for the technical energy increase of the city in parallel with its energy supply area tor three dates chosen during the 19th and 21th centuries.

Introdução: A síndrome do intestino curto (SIC) representa um estado clínico de má absorção grave, e a gestão dietética de pacientes com SIC é extremamente desafiadora. Uma vez que o grau de desnutrição é frequentemente considerável, a intervenção dietética bem sucedida depende da estimativa mais exata possível das necessidades energéticas para prever as metas da terapia nutricional. Objetivo: Quantificar o gasto energético total (GET) em pacientes com SIC pelo método da água duplamente marcada (ADM). Materiais e Métodos: Neste estudo observacional, o GET foi mensurado pelo método da água duplamente marcada em 22 voluntários, 11 com SIC e 11 controles pareados por sexo, idade e IMC (grupo Controle). O GET foi estimado pela equação de Escott-Stump e a partir de acelerômetro, e foi comparado com o GET determinado pela ADM. O gasto energético em repouso (GER) foi mensurado por calorimetria indireta (CI) e comparado com o GER estimado pela equação de Harris e Benedict. O acelerômetro também foi utilizado para estabelecer o nível de atividade física. Resultados: Os participantes tinham idade (média ± DP) de 53 ± 8 anos. O GET medido por ADM foi significativamente menor no grupo SIC comparado ao grupo Controle (p < 0,01); no entanto, o GET estimado não diferiu significativamente entre os grupos. O GET medido foi significativamente maior do que o GET estimado por fórmula no grupo SIC, (respectivamente 1875 ± 276 e 1517 ± 175 kcal/dia, p < 0,01), assim como para o grupo Controle (2393 ± 445 e 1532 ± 178 kcal/dia, p < 0,01). No entanto, o GET medido foi significativamente menor do que o GET predito a partir do acelerômetro no grupo SIC (2075 ± 298 kcal/dia, p = 0,02), e não diferiu significativamente no grupo Controle (2207 ± 355 kcal/dia, p = 0,21). Não foram verificadas diferenças significantes entre o GER medido e predito para ambos, e entre os grupos. Conclusão: O GET medido em pacientes com SIC foi significativamente maior do que o GET estimado por fórmula, e foi menor quando comparado com os valores dos sujeitos controles. No entanto, o GET estimado a partir do acelerômetro, superestima o GET medido por ADM. As fórmulas atualmente utilizadas na prática clínica parecem subestimar as necessidades de energia de pacientes com SIC. Desta forma, adaptações da estimativa atual, aumentando as prescrições de ingestão energética nestes pacientes parecem ser adequadas para apoiar as necessidades diárias de energia e evitar a subnutrição. / Background: Short bowel syndrome (SBS) is a serious malabsorption disorder, and dietetic management of SBS patients is extremely challenging. Once the degree of undernutrition has been assessed, successful dietary intervention depends on the most accurate estimation and provision of energy needs to provide nutritional therapy goals. Objective: To quantify total energy expenditure (TEE) in SBS patients using the doubly labeled water (DLW) method. Design: In this observational study, TEE was measured by the DLW method in 22 participants, 11 with SBS and 11 gender-age-and BMI-matched controls (Control group). Predicted energy requirements were determined using the Escott-Stump equation and by using and accelerometer, and they were compared with TEE determined with DLW. Resting energy expenditure (REE) was measured using indirect calorimetry and compared with predict REE using the Harris and Benedict equation. The accelerometer was also used to determine physical activity level. Results: Participants were aged (mean ± SD) 53 ± 8 years. Measured TEE was significantly lower in the SBS group compared to the Control group (p < 0.01); however, predicted TEE did not differ significantly between the groups. Measured TEE was significantly higher than predicted TEE for the SBS group, (1875 ± 276 and 1517 ± 175 kcal/d, p < 0.01) and also for the Control group (2393 ± 445 and 1532 ± 178 kcal/d, p < 0.01) when determined by formula. However, measured TEE was significantly lower than predicted TEE (2075 ± 298 kcal/d, p = 0.02) for the SBS group, and did not differ for the Control group (2207 ± 355 kcal/d, p = 0.21) when determined by accelerometer. No significant differences were seen between measured and predicted REE both within and between groups. Conclusion: Measured TEE in SBS patients was significantly higher than predicted using standard equations, but also lower than values for age, BMI and gender-matched non-SBS controls. However, predicted TEE using accelerometer overestimated the measured TEE. Currently-used formulas in clinical practice appear to underestimate energy requirements of SBS patients. Therefore, adjustments to the current estimation, increasing the energy intake requirements in these patients appear to be adequate to support the daily energy requirements and avoid undernutrition.

Uma sessão de exercício aeróbio provoca queda da pressão arterial (PA) e aumento da freqüência cardíaca (FC) pós-exercício. Diversos fatores, como a massa muscular, a intensidade e o gasto energético total do exercício podem influenciar esta resposta. Este estudo verificou as respostas pós-exercício da PA, da FC e de seus mecanismos, avaliando a influência dos fatores citados. Vinte e quatro jovens submeteram-se a quatro sessões: controle(C); exercício com um membro inferior (mmii) em 50% do VO2pico(E1); exercício com dois mmii em 50% do VO2pico (E2); e exercício com dois mmii com a mesma potência de E1(E2/1). As PA sistólica (PAS), média (PAM) e diastólica (PAD), o débito cardíaco (DC), a resistência vascular periférica (RVP), o volume sistólico (VS), a FC e a modulação autonômica cardíaca foram medidos. Após o exercício, a PAS e o DC diminuíram e a RVP aumentou em E2. A PAD e PAM não se alteraram. A FC aumentou e o VS e o componente de alta freqüência da variabilidade da FC diminuíram em E1 e E2 (maior em E2). Concluindo: o exercício aeróbio promove hipotensão pós-exercício, devido à queda do DC pela redução do VS. O gasto energético total do exercício é o principal determinante desta resposta. A FC permanece elevada pós-exercício devido ao retardo da reativação vagal. A intensidade e o gasto energético do exercício são os principais determinantes desta resposta / A single bout of aerobic exercise reduces blood pressure (BP) and increases heart rate (HR) during the recovery period. Many factors, such as exercise intensity, muscle mass and total energy expenditure might influence this response. This study verified post-exercise responses of BP, HR and their mechanisms, evaluating the influence of previous factors. Twenty-four subjects underwent four sessions: control (C); exercise with one leg at 50% of VO2peak (E1); exercise with two legs at 50% of VO2peak (E2); and exercise with two legs and the same workload employed in E1 (E2/1). Systolic, mean, and diastolic BPs (SBP, MBP, DBP), systemic vascular resistance (SVR), cardiac output (CO), stroke volume (SV), HR, and cardiac autonomic modulations were measured before and after interventions. After exercise, SBP and CO decreased, while SVR increased in E2. DBP and MBP did not change. HR increased, while SV and the high frequency band of HR variability decreased in E1 and E2 (more in E2). In conclusion: aerobic exercise produced post-exercise hypotension by a decrease in CO, via a decrease in SV. This response is determined by the exercise total energy expenditure. HR is elevated after exercise due to a delay in the restoration of vagal activity to the heart. Exercise intensity and total energy expenditure influence this response. Key-words: aerobic exercise, muscle mass, total energy expenditure, relative intensity, blood pressure, heart rate, autonomic modulation

Materials play an important role in society. Historically, and even at present, materials have been discovered by trial and error, and many of the most useful materials have been discovered by chance. The high-throughput approach aims to remove (as much as possible) chance and guesswork at the experimental level by filtering out materials candidates that are not predicted to exist. Many successes have been recorded. In the high-throughput approach to materials discovery, machined-learned models of materials are created from databases of theoretical materials. These databases are the result of millions of density-functional-theory (DFT) simulations. The size and accuracy of the data in the databases (and, consequently, the predictions of machined-learned models) are most affected by the band energy calculation; most of the computation of a DFT simulation is computing the band energy in the self-consistency cycle, and most of the error in the simulation comes from band energy error. The band energy is obtained from a two-part multidimensional numerical integral over the Brillouin or irreducible Brillouin zone. A quadratic approximation and integration algorithm for computing the band energy in 2D and 3D is described. Analytic and semi-analytic integration of quadratic polynomials over simplices improves the accuracy and efficiency of the calculation. A method is proposed for estimating the error bounds of the quadratic approximation that does not require additional eigenvalues. Error propagation of approximation errors leads to an adaptive refinement approach that is driven by band energy error. Because adaptive meshes have little symmetry, integration is performed within the irreducible Brillouin zone, and a general algorithm for computing the irreducible Brillouin zone is described. The efficiency of quadratic integration is tested on realistic empirical pseudopotentials. When compared to current integration methods, uniform quadratic integration over the irreducible Brillouin zone sometimes results in fewer k-points for a given accuracy. Adaptive refinement fails to improve integration performance because band energy error bounds are inaccurate, especially at accidental crossings at the Fermi level.

Consistently, reports in the literature have identified that a sedentary lifestyle contributes to the progression of a range of chronic degenerative diseases. The measurement of energy expenditure and physical activity pattern in children is a challenge for all professionals interested in paediatric health and from a broader perspective, the public health fraternity charged with considering longer term health consequences of physical inactivity. The primary objective of this thesis was to identify a suitable indirect and objective measurement technique for the assessment of energy expenditure and physical activity pattern in children. The ideal characteristics of such a technique are that it should be reproducible and have been validated against a criterion reference method. To achieve this goal, a series of methodological studies were undertaken (Chapters II and III). This work was essential to increase accuracy during the individualised laboratory calibration process and further minimise prediction errors when analysing data from 7 days of monitoring under free-living conditions in the second part of the study (Chapters IV and V). In the first study to verify the combined effect of body position, apparatus and distraction on children's resting metabolic rate (RMR), experiments were carried out on 14 children aged 8-12 (mean age = 10.1 years ± 1.4). Each participant underwent 2 test sessions, one week apart under three different situations: a) using mouthpiece and nose-clip (MN) or facemask (FM); b) sitting (SEAT) or lying (LY) and c) TV viewing (TV) or no TV viewing. In the first session, following 20 min rest and watching TV, the following protocol was used: LY: 20 min - stabilisation; 10 min using MN and 10 min using FM. Body position was then changed to seated: 20 min stabilisation; 10 min using FM; 10 min using MN. In the second session, FM and MN order was changed and participants did not watch TV. Data were analysed according to the eight combinations among the three studied parameters. Repeated measures ANOVA indicated statistically significant differences for &VO2 (p=0.01) and RMR (p=0.02), with TVMNSEAT showing higher values than TVFMLY. Bland-Altman analysis showed a bias for &VO2, &VCO2, RQ and RMR between TVFMLY and TVMNSEAT of -17.8±14.5 ml.min-1, -8.8±14.5 ml. min-1, 0.03±0.05 and -115.2±101.9 kcal.d-1, respectively. There were no differences in RMR measurements due to body position and apparatus when each variable was isolated. Analyses of distraction in three of four combinations indicated no difference between TV and no TV. In summary, different parameter combinations can result in increased bias and variability and thereby reported differences among children's RMR measurement. The second study dealt with treadmill adaptation and determination of self-selected (SS) walking speed. Assessment of individual and group differences in metabolic energy expenditure using oxygen uptake requires that individuals are comfortable with, and can accommodate to, the equipment being utilised. In this study, a detailed proposal for an adaptation protocol based on the SS was developed. Experiments were carried out on 27 children aged 8-12 (mean age = 10.3±1.2 yr). Results from three treadmill tests following the adaptation protocol showed similar results for step length with no significant differences among tests and lower and no statistically significant variability within- and between-days. Additionally, no statistically significant differences between SS determined over-ground and on a treadmill were verified. These results suggest that SS speed determined over-ground is reproducible on a treadmill and the 10 min familiarisation protocol based on this speed provided sufficient exposure to achieve accommodation to the treadmill. The purpose of the third study was to verify within- and between-day repeatability and variability in children's oxygen uptake ( &VO2), gross economy (GE) [ &VO2 divided by speed] and heart rate (HR) during treadmill walking based on SS. 14 children (mean age = 10.2±1.4 yr) undertook 3 testing sessions over 2 days in which four walking speeds, including SS, were tested. Within- and between-day repeatability was assessed using the Bland and Altman method and coefficients of variability (CV) were determined for each child across exercise bouts and averaged to obtain a mean group CV value for &VO2, GE and HR per speed. Repeated measures ANOVA showed no statistically significant differences in within- or between-day CV for &VO2, GE or HR at any speed. Repeatability within and between-day for &VO2, GE and HR for all speeds was verified. These results suggest that submaximal &V O2 during treadmill walking is stable and reproducible at a range of speeds based on children's SS. In the fourth study, the objective was to establish the effect of walking speed on substrate oxidation during a treadmill protocol based on SS. Experiments were carried out on 12 girls aged 8-12 (mean age = 9.9±1.4 yr). Each participant underwent 2 test sessions, one week apart. Workloads on the treadmill included 2 speeds slower than SS (1.6 [V1] and 0.8 km.h-1 [V2] slower than SS), SS (V3), and a speed 0.8 km.h-1 faster than SS (V4). Indirect calorimetry from respired gas measurements enabled total fat (FO) and carbohydrate (CHO) oxidation rates to be calculated according to the non-protein respiratory quotient (Peronnet and Massicote, 1991) and percentage of CHO and FO calculations using equations from McGilvery and Goldstein (1983). Repeated measures ANOVA followed by a Tukey Post Hoc test (p< 0.05) was used to verify differences in CHO and FO rates among speeds. Paired T-test was used to verify differences in CHO and FO rates between tests per velocity. The reliability between-day was assessed using intraclass correlation coefficient (ICC). Results showed significant differences for CHO among all speeds, as well as significant differences for FO between V1 and V2 against V3 and V4 in both tests. Analyses between trials per velocity showed no significant substrate use differences as well as acceptable reliability. At the self-selected speed (V3) there was an accentuation in FO reduction as well as an increase in CHO oxidation. The purpose of the fifth study was to determine whether there were differences in substrate oxidation between girls (G) and women (W) during a treadmill protocol based on SS. Experiments were carried out on 12 G aged 8-12 (mean age = 9.9±1.4 yr) and 12 W aged 25-38 (mean age = 32.3±3.8 yr). The treadmill protocol included 6 min workloads followed by 5 min rest periods. Workloads included 2 speeds slower than SS (1.6 (V1) and 0.8 km.h-1 (V2) slower than SS), SS (V3), and a speed 0.8 km.h-1 faster than SS (V4). Total fat and carbohydrate (CHO) oxidation rates were calculated from indirect calorimetry according to the non-protein respiratory quotient. Repeated measures ANOVA followed by a Tukey Post Hoc test was used to verify intra-test differences in CHO and fat oxidation rates among speeds. Intergroup differences were analysed using paired T-test. Fat utilisation in W achieved a plateau at a relative velocity 0.8 km.h-1 slower than SS, but for G, fat utilisation increased until SS, and then stabilised upon reaching the higher velocity. CHO oxidation curves rose abruptly above V2 for W, while for G the acute increase occurred after SS (V3). Collectively, these results indicate that as walking intensity increases G are able to meet the energy demands of the work by increasing fat oxidation together with the increased CHO oxidation up to SS. In contrast for W, increasing CHO oxidation is associated with an early decrease in fat utilisation at a velocity slower than the self-selected speed. The sixth study dealt with validation of indirect techniques for the measurement of energy expenditure in free-living conditions against the DLW technique. Experiments were carried out on 19 children aged 8-12 (mean age = 10.3±1.0 yr). To indirectly predict energy expenditure 12 different procedures were used. Only one procedure, combining activity and heart rate (AHbranched), was based on a group equation, the others were based on individualised regression. Three of the individually-based techniques were able to accurately predict energy expenditure in free-living conditions. These tecniques were HRPAnetRMR using HRnet [HR exercise minus sleep HR (SHR)] against PAnet (measured PA exercise minus measured RMR) and upper and lower body equations corrected by RMR; HRPAnet4act using the same procedure but corrected by the mean resting &VO2 for 4 resting activities [(4act) = supine watching TV, sitting watching TV, sitting playing computer games and standing], and HRPALBnet4act using only lower body activities and corrected by 4act. HRPAnetRMR was only slightly more accurate than HRPAnet4act and HRPALBnet4act, but this technique is only adjusted by RMR whereas the other two are heavily dependent on more complex laboratory calibration. Bland and Altman (1986) analyses showed no significant differences between AHbranched predicted and measured TEE using the DLW technique. A SEE of 79 kcal.d-1 and a mean difference of 72 kcal.d-1, with a 95% CI ranging from -238 to 93.9 kcal.d-1 was found. In addition, no significant differences between predicted HRPAnetRMR and measured TEE using DLW were found, showing an SEE of 99 kcal.d-1 and a mean difference of -67 kcal.d-1, and a 95% CI ranging from -276.6 to 141.9 kcal.d-1. AHbranched and HRPAnetRMR were both valid and similarly suitable for the prediction of energy expenditure in children under free-living conditions. Significant associations between DLWAEE and the after-school time window indicated that this time window as an important discretionary period representative of children physical activity. However, the duration of the after-school time windows should be more carefully considered. Accelerometer data showed a better association between the largest after-school time window (3.5 hr) and measured TEE. The final study, completed with 19 children aged 8-12 (10.3±1.0 yr) highlighted, under laboratory conditions across a range of walking and running speeds, the inadequacy of the use of the standard MET in children. This traditional approach overestimates energy expenditure with an increased difference linearly related to speed increments. Minute-by-minute analyses of 7 days of free-living monitoring showed an average overestimation of 64 minutes per day for moderate-to-vigorousphysical- activity (MVPA) using the standard MET compared with the individually measured MET. For all intensities, these differences were statistically significant (p< 0.001). The second part of this study showed a variability of 20% in the average time spent at MVPA when comparing HR I 140 bpm and HR > 50%P &VO2 (P &VO2 = the highest &VO2 observed during an exercise test to exhaustion). Results of the current study compared to observations in the literature showed that HR I 140 bpm consistently estimates lower MVPA time than HR > 50%P &VO2. When these two PA indices were compared with individual and standard MET measured minute-byminute, statistically significant differences were verified among all of them at MPA, but no differences were verified at VPA, except between individual and standard METs. However, whether each one of the PA indices used are under- or overestimating time at MVPA is still debatable due to the lack of a gold standard. Finally, each index used in this study classified different numbers of participants as achieving the PA target of 60 min.d-1. The wide variability between indices when attempting to classify children who are achieving the recommended target is cause for great concern because habitually these indices are utilised as screening tools in paediatric and public health settings and used to guide behavioural interventions.

There is an increase in the prevalence of obesity among people with schizophrenia thought to be due in part to the weight enhancing side-effects of medications commonly used to treat the symptoms of schizophrenia. Despite the deleterious health effects associated with obesity and its impact on quality of life and medication compliance, little is known about body composition and energy expenditure in this clinical group. The primary purpose of this thesis was to enhance understanding of body composition and energy expenditure, particularly resting energy expenditure in men with schizophrenia who take atypical antipsychotic medications. Unique to this investigation is the evaluation of clinical tools used to predict body composition and energy expenditure against reference methodologies in men with schizophrenia. Further, given the known links between obesity and physical activity, an additional but less comprehensive component of the thesis was a consideration of total and activity energy expenditure in addition to the interaction between psychiatric symptoms, side-effects of antipsychotic medications and physical activity also occurred as part of this thesis. Collectively, the goals of this thesis were addressed through a series of studies – the first two studies were related to the measurement and characteristics of body composition in men with schizophrenia, while the third and fourth studies were related to the measurement and characteristics of resting energy expenditure in men with schizophrenia. The fifth and sixth studies the utilised doubly labelled water technique to quantify activity and total energy expenditure in a small group of men with schizophrenia and explored the use of accelerometry in this cohort. The final study briefly considered the impact of psychiatric symptoms and self-reported medication side-effects on objectively measured physical activity. In the first study, thirty-one male adults previously diagnosed with schizophrenia and sixteen healthy male controls were recruited. Estimates of body composition derived from an anthropometry-based equation and from bioelectric impedance analysis (BIA) using deuterium dilution as the reference methodology to determine total body water were compared. The study also determined the validity of equations commonly used to predict body composition from BIA in the men with schizophrenia. A further aim was to determine the superiority of either BIA or body mass index (BMI) as an indicator of obesity in this cohort. The inclusion of the control group, closely matched for age, body size and body composition demonstrated that there was no difference in the ability of body composition prediction methods to distinguish between fat and fat-free mass (FFM) in controls and men with schizophrenia when both groups had similar body composition. However this study indicated that an anthropometry-based equation previously used in people with schizophrenia was a poor predictor of body composition in this cohort, as evidenced by wide limits of agreement (25%) and systematic variation of the bias. In comparison, the best predictor of percentage body fat (%BF) in this group was gained when impedance values were used to predict percentage body fat via the equation published by Lukaski et al (1986). Although percentage body fat was underpredicted using the Lukaski et al. (1986) equation, the mean magnitude was relatively small (1.3%), with the limits of agreement approximately 13%. Linear regression analysis revealed that %BF predicted using the Lukaski et al. (1986) equation explained 25% more of the variance in percentage body fat than BMI. Further, this study also indicated that BIA was more sensitive than BMI in distinguishing between overweight and obesity in this cohort of men with schizophrenia. Because of the almost exclusive use of BMI as an indicator of obesity in people with schizophrenia, the level of excess body fat may be in excess of that previously indicated. The second study extended the examination of body composition in men with schizophrenia. In this study, the thirty-one participants with schizophrenia (age, 34.2 ± 5.7 years; BMI, 30.2 ± 5.7 kg/m2) were individually matched with sedentary controls by age, weight and BMI. Deuterium dilution was used to distinguish between FFM and fat mass. The previous study had indicated that while BIA was a suitable group measure for obesity, on an individual level the technique lacked the precision required for investigating body composition in men with schizophrenia. Waist circumference was used as an indicator of body fat distribution. The findings of this study indicated that in comparison with healthy sedentary controls of similar body size and age, men with schizophrenia had higher levels of body fat which was more centrally distributed. Percentage body fat was on average 4% higher and waist circumference, on average 5 cm greater in men with schizophrenia than the sedentary controls of the same age and BMI. Further, this study indicates that the use of BMI to predict body fat in men with schizophrenia will result in greater bias than when it is used to predict body fat in other sedentary men. Commonly used regression equations to predict energy requirements at rest are based on the relationships between weight and resting energy expenditure (REE) and in such equations, weight acts as a surrogate measure of FFM. The objectives of study three were to measure REE in a small group of men with schizophrenia who were taking the antipsychotic medication clozapine and to determine whether REE can be predicted with sufficient accuracy to substitute for the measurement of REE in the clinical and/or research settings. Body composition was determined using deuterium dilution and REE was measured using a Deltatrac Metabolic Cart via a ventilated hood. The male participants, (aged 28.0 ± 6.7 yrs, BMI 29.8 ± 6.8 kg/m2) were weight stable at the time of the study and had been taking clozapine for 20.5 ± 12.8 months, with doses of 450 ± 140 mg/day. Of the six prediction equations evaluated, the equation of Mifflin et al. (1990) with no systematic bias, the lowest bias and the lowest limits of agreement proved to be the most suitable equation to predict REE in this cohort. The overestimation of REE can be corrected for by deducting 160 kcal/day from the predicted REE value when using the Mifflin et al. (1990) equations. However, the magnitude of the error associated with the prediction of REE for an individual is 370 kcal/day. The findings of this study indicate that REE cannot be predicted with sufficient individual accuracy in men with schizophrenia, therefore it was necessary to measure rather than predict REE in subsequent studies. In the fourth study, indirect calorimetry (Deltatrac Metabolic Cart via ventilated hood) and deuterium dilution were used to accurately determine REE, respiratory quotient (RQ) and FFM in 31 men with schizophrenia and healthy sedentary controls individually matched for age and BMI. Data from this study indicated that gross REE was lower in men with schizophrenia than in healthy sedentary controls of a similar age and body size. However, there was no difference between the groups in REE when REE was adjusted for FFM using the mathematically correct method (analysis of covariance with FFM as the covariate). There was however a statistically and clinically significant difference in resting, fasted RQ between men with schizophrenia and controls, suggesting that RQ rather than REE may be an important correlate worthy of further investigation in men with schizophrenia who take antipsychotic medications. Studies five and six involved the application of the doubly labelled water (DLW) technique to accurately determine total energy expenditure (TEE) and activity energy expenditure (AEE) in a small group of men with schizophrenia who had been taking the atypical antipsychotic medication clozapine. The participants were those who took part in study three. The purpose of these studies was to assess the validity of a commercially available tri-axial accelerometer (RT3) for predicting free-living AEE and to investigate TEE and AEE in men with schizophrenia. There was poor agreement between AEE measured using DLW and AEE predicted using the RT3. However, using the RT3 to measure inactivity explained over two-thirds of the variance in AEE. This study found that the relationship between current AEE per kilogram of body weight and change from baseline weight in men taking clozapine was strong although not significant. The sedentary nature of the group of participants in this study was reflected in physical activity levels, (PAL, 1.39 ± 0.27), AEE (435 ±352 kcal/day) and TEE (2511 ± 606 kcal/day) that fell well short of values recommended by WHO (2000) for optimal health and to prevent weight gain. Given the increasing recognition of the importance of sedentary behaviour to weight gain in the general community, further examination of the unique contributing factors such as medication side effects and symptoms of mental illness to activity levels in this clinical group is warranted. The final study used accelerometry (RT3) to objectively measure activity in a group of 31 men with schizophrenia who had been taking atypical antipsychotic medications for more than four months. The purpose of this study was to explore the relationships between psychiatric symptomatology, side-effects of medication and physical activity. Accelerometry output was analysed to provide a measure of inactivity and moderate intensity activity (MIA). The well-validated and reliable standardised clinical interview, the Positive and Negative Syndrome Scale (PANSS) was used as a measure of psychiatric symptoms. Perceived side-effects of medication were assessed using the Liverpool University Neuroleptic Rating Side-Effects Scale (LUNSER). Surprisingly, there was no relationship reported between any measures of negative symptoms and physical inactivity. However, self-reported measures of medication side-effects relating to fatigue, sleepiness during the day and extrapyramidal symptoms explained 40% of the variance in inactivity. This study found significant relationships between some negative symptoms and moderate intensity activity. Despite the expectation that as symptoms of mental illness reduce, inactivity may diminish and moderate intensity activity will increase, it may not be surprising that in practice this is an overly simplistic view. It may be that measures of social functioning and possibly therefore cognition may be better predictors of physical activity than psychiatric symptomatology per se.

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