The purpose of the following study was to re-address the energy requirements of Canadian Armed Forces (CAF) during training in a cold winter environment. Twenty CAF personnel were recruited to participate in a 5-day winter training exercise at Canadian Forces Base Meaford in Ontario, Canada. Energy expenditure (n=10) and body composition (n=14) were measured via the doubly labelled water (DLW) method and the deuterium isotope dilution technique, respectively. Mean total daily energy expenditure (TDEE) was 4900±693 kcal·day-1 with no significant differences observed between sexes. Body mass and body composition of CAF personnel changed significantly (p < 0.05) across the 5-day exercise. This decrease was associated with a significant (p < 0.05) reduction in fat mass. Despite these losses, participants were able to maintain high physical activity level (PAL) values (2.6) and high TDEE levels throughout the study period. It is recommended to increase the caloric content of the rations via additional supplements that provide energy-dense foods in bar format that can be easily consumed at the convenience of the individual. / February 2016

Case control studies have shown that a high consumption of fish, olive oil, and cooked vegetables is associated with a decreased risk of developing rheumatoid arthritis (RA). These foods have a central position in the traditional Cretan Mediterranean diet, and it has been suggested that dietary factors contribute to the low prevalence of RA in Mediterranean countries. The overall aim of this thesis was to examine whether a modified Cretan Mediterranean diet can reduce signs and symptoms of RA. This was investigated in a three-month dietary intervention trial in which 51 patients with well controlled, although active RA of at least two years duration took part. A further aim was to study the compliance with the experimental and control diets used in the study, and to validate the diet history interview method used to assess the dietary intake. The validation was carried out by means of biological markers of dietary intake. From baseline to the end of the study the group that had adopted the Cretan Mediterranean diet (MD group; n=26) obtained a reduction in disease activity, improved physical function, and improved vitality, while no changes was seen in the control diet group (CD group; n=25). According to the dietary assessments, the intake frequencies of antioxidant-rich food items increased in the MD group. This group also had a significantly higher intake of vitamin E, vitamin C and selenium compared to the CD group. Despite the reported increase in the consumption frequencies of antioxidant-rich foods, the plasma levels of carotenoids, vitamin C, lipid adjusted tocopherols, uric acid and urine malondialdehyde, a marker of oxidative stress, were unchanged at the end of the study. The plasma levels of retinol, vitamin C and uric acid were, however, correlated to indices of disease activity. Changes in the reported consumption of food groups with relevance to the fat intake were also observed in the MD group, including an increased intake of fish, shellfish and poultry, and a decreased intake of meat and high fat dairy products. As a result, the total fat intake was lower in the MD group compared to the CD group. Furthermore, in the MD group a slightly higher percentage of the energy intake was derived from polyunsaturated fatty acids and a lower percentage from saturated fatty acids. This group also had a lower ratio of n-6:n-3 fatty acids. A corresponding change in the relation between n-6 and n-3 fatty acids was also observed in s-phospholipids. The validation of the diet history interview method showed that the diet history interview could capture the dietary intake fairly well. The validity of the reported dietary intake did not differ between the MD and the CD group, which indicates that the dietary assessment was not biased by the dietary intervention.

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal.

L’augmentation de la dépense énergétique (DE) par une augmentation de l'activité physique (AP) participe au maintien et à l’amélioration de la santé. La mesure à grande échelle de la DE totale (DET) en général et AP en particulier se heurte à des difficultés pratiques de recueil de données, de validité et aux coûts. Bien que dans la littérature de nombreux accéléromètres permettent d’estimer la DET, il y a encore des limites quant à la mesure de l’intensité de l’AP, élément qui influence l’état de la balance énergétique et le bénéfice pour la santé de l’AP. De plus, peu de comparaisons entre les différents accéléromètres sont disponibles. La présente étude avait pour but d’évaluer la capacité de deux accéléromètres (Actical et Sensewear Armband) pour estimer la DET en comparaison avec la technique de l’eau doublement marquée (EDM) ; d’évaluer la concordance entre les accéléromètres dans la mesure de la DE au repos (DER) en comparaison avec la technique de la calorimétrie indirecte (CI) et d’évaluer la DE liée à l’AP en comparaison avec la technique de la CI. Les résultats montrent qu’il y a une très bonne corrélation entre la CI et les accéléromètres dans la mesure de la DER(r > 0.80, p<0.001) et une bonne corrélation entre les accéléromètres et l’EDM dans la mesure de la DET(r>0.75, p<0.001). Pour la mesure de l’intensité de l’AP, l’ACT est plus précis (r=0.80, p<0.001)) que le SWA à la marche, le SWA est meilleur(r=0.80, p<0.001) au vélo. Cette étude permet d’affirmer que le SWA et l’ACT sont des alternatives valables pour mesurer la DE. / The increase in energy expenditure by the increase of physical activity contributes to maintaining and improving health. The large-scale measurement of total energy expenditure in general and physical activity in particular, is faced with difficulties of data collection, validity and cost. Although literature suggests that many accelerometers are used to estimate total energy expenditure, there are still limits as to the measurement of the intensity of physical activity, which is one of the factors that influences the energy balance and health benefits of physical activity. In addition, few comparisons between the different accelerometers are available. This study aimed to evaluate the ability of two accelerometers (Actical and SensWear Armband) to estimate total energy expenditure compared with the technique of doubly labelled water; to assess the correlation between the two accelerometers in the measurement of resting energy expenditure, compared with the technique of indirect calorimetry and finally to assess energy expenditure linked to physical (walking and cycling) at different intensities, in comparison with the indirect calorimetry technique. The results show a very good correlation between indirect calorimetry and the two accelerometers(r > 0.80, p<0.001) in the measurement of resting energy expenditure and a good correlation between accelerometers and the gold standard technique (doubly labeled water) in the measurement of total energy expenditure(r>0.75, p<0.001). To measure the intensity of physical activity, Actical is more accurate than SensWear Armband(r=0.80, p<0.001) at low intensity while the SensWear Armband is better at higher intensity (r=0.80, p<0.001). This study provides evidence that these two accelerometers are suitable alternatives for measuring energy expenditure.

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.

No description available.

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.