Made available in DSpace on 2016-12-06T17:07:22Z (GMT). No. of bitstreams: 1 Eduardo Wust.pdf: 379454 bytes, checksum: 0de08273cb40c15eab82875af50619e9 (MD5) Previous issue date: 2009-08-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to analyze the influence of different models of shoes in tibial acceleration, in a uniaxial accelerometer. Twenty subjects participated in the study, gender female, no history of musculo-skeletal injuries in lower limbs and spine in the last year. In this study also found the strength of soil reaction, through a platform of force under the same conditions of acquisition of tibial accelerometry (with 4 different types of footwear and barefoot). This study aimed at analyzing: peak tibial acceleration, the rate of acceptance of weight and rate of damping in the 5 cases of study, the statistical treatment was descriptive statistics, performed the Kolmogorov-Smirnov test to verify the normal distribution of data for the comparison between the conditions we used the One-Way ANOVA test for normal distribution of data (parametric test) with post hoc test of Tukey (p <0.05). The results showed that the situation barefoot had higher rates of tibial acceleration than with the use of tennis shoes and salto anabela, tennis shoes showed significant differences between all the other conditions examined. For the rate of acceptance of the weight we found significant differences between the situation barefoot for other situation and variable damping rate, the use of tennis shoes had a greater damping than the other shoes. / O presente trabalho teve como objetivo analisar a influência de diferentes modelos de calçados na aceleração tibial, através de um acelerômetro uniaxial. Participaram do estudo 20 sujeitos, do gênero feminino, sem histórico de lesão músculo-esquelética nos membros inferiores e na coluna vertebral no último ano. Nesse estudo foi verificada também a força de reação do solo, através de uma plataforma de força, nas mesmas condições das aquisições da acelerometria tibial (com 4 diferentes tipos de calçado e descalço). Foram analisadas as variáveis: picos de aceleração tibial, a taxa de aceitação do peso e o índice de amortecimento durante as diferentes situações de estudo. A análise estatística foi composta de estatística descritiva, realizando se o teste de Kolmogorov-Smirnov para verificar a distribuição normal dos dados, já para a comparação entre as condições foi utilizado o teste One-Way ANOVA para distribuição normal dos dados (teste paramétrico), seguido do teste de Post Hoc de Tukey, optou-se um valor de p<0,05. Os resultados mostraram que a situação descalça apresentou maiores índices de aceleração tibial em relação ao uso do tênis e do salto anabela, o tênis apresentou, ainda, diferenças significativas entre todas as demais condições analisadas. Para a taxa de aceitação do peso foi encontrado diferenças significativas entre a condição descalça e todos os calçados utilizados, na variável em que se considerou o índice de amortecimento, o uso do tênis apresentou o melhor resultado se comparado com os demais calçados, sendo o calçado que teve um amortecimento maior em relação aos demais calçados.

INTRODUÇÃO: Por se tratar de um problema grave, incapacitante e frequente de saúde, estratégias têm sido investigadas para buscar independência funcional de pacientes com acidente vascular cerebral em todo o mundo. O monitoramento do gasto energético e atividade física é importante para que se alcance todas as metas terapêuticas, sem riscos adicionais, garantindo a estes pacientes uma vida mais ativa e independente. Neste estudo nosso objetivo foi avaliar a confiabilidade e concordância de um acelerômetro triaxial como ferramenta para avaliação do gasto energético de pacientes pós acidente vascular cerebral durante o regime de internação em um centro de reabilitação. MÉTODOS: Para a realização deste estudo, 24 pacientes com sequelas de acidente vascular cerebral em regime de internação em centro de reabilitação foram submetidos a um teste de caminhada em esteira utilizando simultaneamente o analisador de gases e o acelerômetro triaxial Dynaport. Em seguida os pacientes foram monitorados por cinco dias durante suas atividades habituais de reabilitação e detes foram analisados os 3 dias intermediários que permitiam a análise durante 24 horas. Os valores do gasto energético total e na atividade física durante o teste de caminhada foram comparados através do coeficiente de correlação intraclasse e do coeficiente de correlação de concordância com as quilocalorias encontradas no analisador de gases, sendo também utilizado o coeficiente de correlação intraclasse para verificar a concordância do gasto energético total e do gasto energético em atividade física nos três dias de monitoramento. RESULTADOS: Foi possível observar confiabilidade quase perfeita (ICC 0,94) e uma forte consistência (CCC 0,88) entre as quilocalorias e o gasto energético total do teste e uma confiabilidade substancial com baixa consistência quando comparado o gasto energético na atividade física. Encontramos, além disso, uma confiabilidade quase perfeita entre as medidas de gasto energético total (ICC 0,86), gasto energético na atividade física (ICC 0,86) e do gasto energético nas diferentes posições corporais e movimentos avaliados nos 3 dias analisados. Foi possível observar também que os participantes permaneciam a maior parte do tempo em atividades sedentárias. CONCLUSÃO: Conclui-se que o acelerômetro triaxial Dynaport é válido como instrumento de avaliação do gasto energético em pacientes com acidente vascular cerebral / INTRODUCTION: Once it is a serious, incapacitating and prevalent health condition, strategies for achieving functional independence of patients with stroke are being investigated all over the world. The energy expenditure and physical activities monitoring is important for fulfilling all the therapeutic goals, allowing patients to live an independent and more active life, without adding risks. In this study, our objective was to evaluate the reliability and concordance of a triaxial accelerometer as a tool for quantifying energy expenditure of stroke inpatients of a rehabilitation hospital. METHODS: 24 stroke inpatients of a rehabilitation hospital undertook a treadmill walk test and were simultaneously assessed by a gas analyzer and the triaxial accelerometer Dynaport. They were then monitored by the accelerometer for three days for further analysis of energy expenditure and activity related energy expenditure for 24 and 12 hours. The measurements of total energy expenditure and activity related energy expenditure of both the accelerometer and the gas analyzer were compared and analyzed with the Intraclass Correlation Coefficient and the Concordance Correlation Coefficient statistics. The reports of energy expenditure and activity related energy expenditure of the Dynaport of the monitoring days were also compared and analyzed with the Intraclass Correlation Coefficient and the Concordance Correlation Coefficient statistics. RESULTS: It was possible to observe an almost perfect reliability (ICC 0.94) and a strong consistence (CCC 0.88) between the total energy expenditure measured by both the Dynaport and the gas analyzer, and a substantial reliability with weak consistency when the activity related energy of Dynaport was compared with the gas analyzer. In addition, the three-day monitoring yielded an almost perfect reliability of total energy expenditure (ICC 0.86) and activity related energy expenditure (ICC 0.86). It was also possible to observe that, most of the time, the participants undertook sedentary activities. CONCLUSION: The triaxal accelerometer Dynaport is reliable as a tool for evaluating energy expenditure of patients with stroke

Submitted by Anelise Milech (anelisemilech@gmail.com) on 2017-02-10T12:17:15Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) carolina bohns mattea.pdf: 1296240 bytes, checksum: 348123e878bec38baae1e3deb80c647f (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-02-16T20:15:38Z (GMT) No. of bitstreams: 2 carolina bohns mattea.pdf: 1296240 bytes, checksum: 348123e878bec38baae1e3deb80c647f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2017-02-16T20:17:49Z (GMT) No. of bitstreams: 2 carolina bohns mattea.pdf: 1296240 bytes, checksum: 348123e878bec38baae1e3deb80c647f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-02-16T20:18:08Z (GMT). No. of bitstreams: 2 carolina bohns mattea.pdf: 1296240 bytes, checksum: 348123e878bec38baae1e3deb80c647f (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-01-20 / Sem bolsa / Este estudo transversal de base escolar teve como objetivo caracterizar as aulas de Educação Física nos anos iniciais do ensino fundamental das escolas públicas e privadas da cidade de Pelotas, RS. Foram analisados a duração e a intensidade dos esforços físicos, conteúdos desenvolvidos e ação do professor durante as aulas. Compuseram a amostra 19 escolas da zona urbana e rural da cidade, totalizando 93 turmas e 404 alunos. Para as observações das 275 aulas de Educação Física foi utilizado o instrumento System for Observing Fitness Instruction Time (SOFIT). O nível de atividade física dos estudantes durante as aulas foi mensurado pelo acelerômetro Actigraph wGT3X+. A duração média de tempo das aulas de Educação Física observada pelo SOFIT foi de 29,9 minutos (DP 8,1). Destes, 14,2 minutos (47,8%) foram despendidos em atividades sedentárias, 7,8min (26,2%) em atividades leves, 2,8min (9,3%) em atividades moderadas e 4,9 minutos (16,7%) em atividades físicas vigorosas de acordo com a acelerometria. O contexto das aulas mais frequentes foi o conteúdo jogos estruturados (36,0%). Já a ação do professor gerenciando (45,6%) foi a mais observada. Ficou evidenciada a necessidade de um maior aproveitamento do tempo das aulas para o desenvolvimento de atividades físicas moderadas à vigorosas. Contudo, a Educação Física do 1º ao 5º ano se mostrou estruturada e planejada com relação à ação do professor e aos conteúdos desenvolvidos. / This cross-sectional, school-based study aimed to characterize Physical Education classes in the initial years of elementary education in public and private schools in the city of Pelotas, RS. The duration and intensity of the physical efforts, contents developed and action of the teacher during the classes were analyzed. The sample comprised 19 schools in the urban and rural areas of the city, totaling 93 classes and 404 students. For the observations of the 275 classes of Physical Education was The System for Observing Fitness Instruction Time (SOFIT) instrument was used. The level of student physical activity during class was measured by the Actigraph wGT3X + accelerometer. The mean duration of physical education classes observed by SOFIT was 29.9 minutes (SD 8.1). Of these, 14.2 minutes (47.8%) were spent in sedentary activities, 7.8min (26.2%) in mild activities, 2.8min (9.3%) in moderate activities and 4.9 minutes (16 , 7%) in vigorous physical activities according to the accelerometry. The context of the most frequent classes was structured content games (36.0%). Already the action of the teacher managing (45.6%) was the most observed. It was highlighted the need for a Greater use of class time for the development of moderate to vigorous physical activities. However, Physical Education from the 1st to 5th year was structured and planned in relation to the teacher's action and the contents eveloped.

La fatigue est un phénomène bien connu dans le monde du sport provoquant une chute des performances et une augmentation du risque de blessures. La communauté scientifique s’intéresse donc à la quantification de ce phénomène au moyen de différents outils d’analyse du mouvement. Cependant certains sports comme la course à pied soumettent les athlètes à des sollicitations mécaniques violentes impactant fortement sur leur santé et leurs performances. Ces sollicitations se traduisent souvent par des chocs importants, un nombre de cycles élevé et sont accompagnées de postures complexes du corps. Les outils d’analyse du mouvement ne sont alors pas toujours adaptés pour la mesures de ces données ni à l’étude du mouvement de l’athlète dans des conditions réelles de pratique. L’accélération apparait alors comme une caractéristique riche en informations. Elle peut permettre de mesurer et d’analyser la pratique de la course à pied afin de quantifier la dérive de la réponse mécanique du corps humain. Par la validation d’outils issus de l’accélérométrie, ces travaux de thèse permettront d’étudier les phénomènes mécaniques intervenant durant la pratique de la course à pied afin de quantifier et prédire leurs effets sur les phénomènes de fatigue des athlètes. / Fatigue is a well known phenomenon in the sports world causing a decrease of performance and an increase of injury risk. The scientific community is therefore concerned with the quantification of this phenomenon using different motion analysis tools. However some sports like running inflict violent mechanical loads to the athletes strongly impacting their health and performance. These loads frequently result in significant shocks, a high number of cycles and are accompanied by complex postures of the body. The motion analysis tools are then not always suitable for the measurement of this information or to study the athlete’s movement in real conditions of practice. The acceleration then appears as a feature rich in information.It can allow to measure and analyze the practice of running in order to quantify the drift of the mechanical response of the human body. By validating accelerometric tools, these thesis works will allow to study the mechanical phenomena intervening in the practice of running in order to quantify and predict their effects on the athlete’s fatigue.

In recent years, physical activity and fitness transitions, described as declines in physical activity and aerobic fitness, coupled with increased sedentary behaviour, have been observed among school-aged children. Consequently, the prevalence of childhood overweight/obesity has also increased considerably. While there is a wealth of evidence supporting such behavioural transitions in higher income countries, there exists a paucity of data on the situation in lower income countries, such as those in Sub-Saharan Africa (SSA). The premise of this thesis was to investigate the robustness of these relationships in other global regions. The first objective was to investigate the evidence for an overweight/obesity, physical activity, and fitness transition among SSA’s school-aged children. Systematic review methodology was used to examine temporal trends and correlates of overweight/obesity, physical activity, fitness, and sedentary behaviour in apparently healthy or population based samples of children (5 - 17 years). The second objective of this thesis was to determine the prevalence and correlates of overweight/obesity and physical activity among Kenyan children aged 9 to 11 years, having contextualised Kenya within the broader situation in SSA. Further, the relationships between self-reported and directly assessed measures of physical activity and sedentary time by weight status in Kenyan children were investigated. The third objective was to examine moderate-to-vigorous physical activity (MVPA) patterns accrued by time of day among Kenyan children using the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE)-Kenya data. Activity patterns in the Kenyan setting were then compared to similar ISCOLE-Canada data from Canadian children, revealing differences and similarities in the accumulation of MVPA, light physical activity, and sedentary time. Systematic review data syntheses revealed a trend towards increasing proportions of overweight/obesity among Sub-Saharan Africa’s school-aged children. Further, urbanization and higher socioeconomic status (SES) were associated with decreased physical activity and aerobic fitness, and increased sedentary behaviours and body composition measures. ISCOLE-Kenya data analyses found a prevalence of childhood overweight/obesity of 20.8% in Nairobi, with few children meeting global physical activity guidelines (12.6%). Mean daily sedentary time was 398 minutes, time spent in light physical activity was 463 minutes, and time spent in MVPA was 36 minutes. Higher SES and parental education attainment were associated with a higher likelihood of children being overweight/obese and a lower likelihood of children meeting the physical activity recommendations. Data analyses also revealed considerable discrepancies in both self-report and direct measures of physical activity by weight status, and weak to moderate correlations between self-report and direct measures of physical activity. Under/healthy weight children had significantly higher directly measured mean daily minutes of MVPA compared to overweight/obese children (39 verses 20 minutes); had lower mean weekend-day minutes of sedentary time (346 verses 365 minutes); and had a higher proportion who met physical activity guidelines (15.5% versus 2.6%). Lastly, while MVPA patterns among urban Kenyan children were largely similar to those of urban Canadian children with regard to relationships by sex, BMI category, and weekday/weekend days; in the Kenyan sample, much unlike many higher income countries, lower SES was associated with higher MVPA.

Accelerometer data can be analyzed using a variety of methods which are effective in the clinical setting. Time-series analysis is used to analyze spatiotemporal variables in various populations. More recently, investigators have focused on gait complexity and the structure of spatiotemporal variations during walking and running. This study evaluated the use of time-series analyses to determine gait parameters during running. Subjects were college-age female soccer players. Accelerometer data were collected using GPS-embedded trunk-mounted accelerometers. Customized Matlab® programs were developed that included Gaussian continuous wavelet transform (CWT) to determine spatiotemporal characteristics, detrended fluctuation analysis (DFA) to examine gait complexity and autocorrelation analyses (ACF) to assess gait regularity. Reliability was examined using repeated running efforts and intraclass correlation. Proof of concept was determined by examining differences in each variable between various running speeds. Applicability was established by examining gait before and after fatiguing activity. The results showed most variables had excellent reliability. Test-retest R2 values for these variables ranged from 0.8 to 1.0. Low reliability was seen in bilateral comparisons of gait symmetry. Increases in running speed resulted in expected changes in spatiotemporal and acceleration variables. Fatiguing exercise had minimal effects on spatiotemporal variables but resulted in noticeable declines in complexity. This investigation shows that GPS-embedded trunk-mounted accelerometers can be effectively used to assess running gait. CWT and DFA yield reliable measures of spatiotemporal characteristics of gait and gait complexity. The effects of running speed and fatigue on these variables provides proof of concepts and applicability for this analytical approach. / Master of Science / Fitness trackers have become widely accessible and easy to use. So much so that athletic teams have been using them to track activity throughout the season. Researchers are able to manipulate data generated from the fitness monitors to assess many different variables including gait. Monitoring gait may generate important information about the condition of the individual. As a person fatigues, running form is theorized to breakdown, which increases injury risk. Therefore the ability to monitor gait may be advantageous in preventing injury. The purpose of this study is to show that the methods in this study are reproducible, respond reasonably to changes in speed, and to observe the changes of gait in the presence of fatigue or on tired legs. Three analyses are used in this study. The first method called autocorrelation, overlays acceleration signals of consecutive foot strikes, and determines the similarity between them. The second method utilizes a wave transformation technique that is able to determine foot contact times. The final method attempts to determine any pattern in the running stride. This method looks for changes in the structure of the pattern. Less structure would indicate a stride that is fatigued. The results showed that the methods of gait analysis used in this study were reproducible and responded appropriately with changes in speed. Small changes in gait were observed due to the presence of fatigue. Further investigation into the use of these methods to determine changes in gait due to the presence of fatigue are warranted.

No description available.

The prevalence of obesity continues to increase despite considerable research and innovation regarding treatment and management strategies. When completed as prescribed, exercise training is associated with numerous health benefits and predictable levels of weight loss. However, under free-living conditions the benefits of exercise are less consistent, suggesting that non-adherence and/or a compensatory response in non-exercise activity thermogenesis (NEAT) may be occurring. The accurate quantification of all components of total energy expenditure (TEE), including TEE itself, was imperative to elucidate the primary research question relating to the impact of exercise on TEE. In addition, the measurement of changes in body composition and the response to prescribed exercise were assessed in methodological and pilot investigations. Following this extensive background, the primary research question relating to the effect of exercise on levels of TEE and the associated implications of such a compensatory response could be more rigorously investigated. The first study investigated the variability in isotopic equilibrium time under field conditions, and the impact of this variability on estimates of total body water (TBW) and body composition when using the deuterium dilution technique. Following the collection of a fasting baseline urine sample, 10 women and 10 men were dosed with deuterium oxide (0.05g/kg body weight). Urine samples were collected every hour for 8 hours. The samples were analysed using isotope ratio mass spectrometry and time to equilibration was determined using three commonly employed data analysis approaches. Isotopic equilibrium was reached by 50, 80 and 100% of participants at 4, 6 and 8 h, respectively. The mean group equilibration times determined using the three different plateau determination methods were 4.8 ± 1.5, 3.8 ± 0.8, and 4.9 ±1.4 h, respectively. Isotopic enrichment, TBW, and percent body fat estimates differed between early sampling times (3-5 h), but not later sampling times (5-8 h). Therefore, sampling < 6 hours post dose compared to sampling ≥ 6 hours resulted in greater relative measurement error in TBW and body composition estimates. Although differences in equilibration time were apparent between the three plateau determination approaches, sampling at 6 hours or later may decrease the likelihood of error in body composition estimates resultant from incomplete isotopic equilibration in a small proportion of individuals. In the second study, the aim was to measure the self-paced walking (SPW) speed of adults ranging in body size from normal to obese. The utility of heart rate monitors to estimate the energy cost of walking was also investigated. Twenty-nine participants (12 normal-weight, 17 overweight or obese) completed two outdoor walking tests to determine their SPW speed. A walking treadmill test with stages below, at, and above the SPW speed was completed to compare the energy expenditure estimates of the Polar S610 and WM42 heart rate monitors with that from indirect calorimetry. The average SPW speed was 1.7 ± 0.1 m*sec-1, which was equivalent to an exercise intensity of 48.6 ± 9.4 %VO2max (61.0 ± 7.1 %HRmax). There was no difference in the energy expenditure estimation between indirect calorimetry (4.7 ± 0.7 kcal*kg*-1*h-1), the S610 (4.8 ± 1.3 kcal*kg*-1*h-1) and the WM42 (4.8 ± 1.6 kcal*kg*-1*h-1). It was concluded that the heart rate monitors provided reasonable energy expenditure estimates at the group level. However considerable error was evident at the individual level, explained in part by exercise heart rate and fitness level, suggesting that an individualised calibration should be performed where possible. An additional finding from this study was that 145 to 215 minutes of SPW per week, dependent upon the level of adiposity, is required to meet the current American College of Sports Medicine (ACSM) guidelines for health of 1000 kcal*wk-1. The purpose of the third study was to establish the level of adherence to a specific exercise prescription (1500 kcal*wk-1) by objectively quantifying unsupervised exercise energy expenditure (ExEE) in a group of obese women. The 16-wk lifestyle intervention consisted of weekly meetings with research staff, combined with promotion of increased ExEE (1500 kcal*wk-1) and a decreased dietary intake (-500 kcal*d-1). Twenty-nine obese females (Body Mass Index = 36.8 ± 5.0 kg*m2, Body Fat = 49.6 ± 3.7 %) from a hospital-based lifestyle intervention were included in the analysis. ExEE was estimated and monitored weekly using heart rate monitoring. Body composition was measured before and after the intervention by dual-energy x-ray absorptiometry (DXA). Results indicated free-living adherence to the exercise prescription was modest and variable, with 14% of participants achieving the 1500 kcal*wk-1. The average weekly ExEE (768 kcal*wk-1) represented 51.2% of the total amount prescribed. ExEE was correlated with changes in body weight (r = 0.65, p < 0.001) and fat mass (r = 0.65, p = 0.0002). Achievement of a 5% weight loss target was dependent on an ExEE level of 1000 kcal*wk-1 (p &lt0.001). Exercise 'adherers' (> 000 kcal*wk-1) lost more weight (-9.9 vs. -4.1 kg), more fat mass (-6.8 vs. -3.0 kg), and more waist circumference (-9.8 vs. -5.6 cm) when compared to 'non-adherers' (< 1000 kcal*wk-1). The results suggest that the extent of supervision and monitoring influenced exercise adherence rates. The variability in adherence highlights the importance of objective monitoring of ExEE. Identification of individuals not complying with program targets may enable intervention staff to provide additional support or make individualised adjustments to the exercise prescription. The fourth study investigated issues relating to the management and interpretation of accelerometry data when the device is to be used to monitor levels of daily physical activity. Given the high between-individual variability in accelerometry output for a given walking speed, the use of a more individualised approach to the data management has been suggested. In addition, accelerometry was used to compare daily physical activity patterns between a supervised and unsupervised exercise prescription of the same dose (1500 kcal*wk-1) in overweight and obese women. Total energy expenditure, activity energy expenditure, and vector magnitude increased significantly during the intervention. Time spent in very low intensity movement decreased from baseline to the intervention (p < 0.01) in both the supervised (-18.6 min*d-1) and unsupervised (-68.5 min*d-1) group, whereas time spent in high and vigorous intensity movement increased significantly from baseline to the intervention (p < 0.05 and p < 0.0001, respectively). The increase in vigorous movement was significantly greater in the supervised group when compared to the unsupervised group (+11.5 vs. +5.4 min*d-1, p < 0.05). Time spent above three different moderate-intensity walking thresholds increased from baseline to the intervention (p < 0.0001). The threshold determination approach significantly affected the resultant outcomes (p < 0.0001) such that the standard threshold was significantly different to both group-specific and individualised approaches. Significant differences were also noted in accelerometer output between treadmill and overground walking (p < 0.0001). A positive finding of this study was that two different interventions aimed at increasing physical activity levels in a group of sedentary and obese women were successful in gaining modest increases in overall daily movement. The change observed appears to be a replacement of sedentary movement with more vigorous physical activity. Collectively, the differences observed between threshold determination approaches, as well as between treadmill and overground walking, highlight the need for standardised approaches to accelerometry data management and analysis. In addition, the findings suggest that obese women may benefit from a certain degree of exercise supervision to ensure compliance, however, strategies to encourage these women to continue with the exercise on their own without supervision are essential to making a sustainable long-term change to their lifestyles. The final study aimed to assess whether obese women compensate for structured exercise by decreasing their NEAT and thereby impeding weight loss. Thirteen participants were prescribed 1500 kcal*wk-1 of exercise through a structured walking program (4 week supervised followed by 4 weeks unsupervised). The energy expenditure of the walks was quantified using individually-calibrated Polar F4 heart rate monitors. The DLW technique was used to measure TEE. Accelerometry measures were also collected throughout and represented an alternative method of quantifying changes in total daily movement patterns resultant from an increase in energy expenditure through exercise. Compliance with the exercise program was excellent, with the average compliance being 94% over the 8-week intervention. The adoption of moderate-intensity exercise in this group of obese women resulted in a 12% decrease in TEE (p = 0.01) and a 67% decrease in NEAT (p < 0.05). No significant change was observed in resting metabolic rate from baseline to the postintervention time-point. Compensation was significantly correlated with dietary report bias (r= -0.84, p = 0.001), body image (r = 0.75, p < 0.01), and bodily pain (r = -0.65, p < 0.05). A linear regression model including dietary reporting bias and the pain score explained 78% of the variation in ΔTEE. Compensators were therefore less likely to underreport their dietary intake, less likely to be self-aware of their obese state, and more likely to be experiencing pain in their daily life. Self-reported dietary intake decreased significantly during the intervention (p = 0.01) with specific decreases noted in fat and carbohydrate intake. The consequence of compensation was evidenced by a lack of significant change in body weight, body composition, or blood lipids (p > 0.05). However, positive outcomes of the study included improvement in the SF-36 scores of general health (p < 0.05) and maintenance of exercise program adherence into the unsupervised phase of the intervention. Qualitative data collected via interview indicated that 85% of participants experienced increased energy and positive feedback from peers during the intervention. This study confirms that exercise prescription needs to be prescribed with an individualised approach that takes into account level of adiposity. The goal of exercise prescription for the obese should therefore be to determine the intensity and modality of exercise that does not activate compensatory behaviours, as this may in turn negate the beneficial effects of the additional energy expenditure of exercise. This study confirms that during the initial phase of an exercise-based weight loss intervention, the majority of obese women compensated for some, if not all, the energy cost of the exercise sessions by reducing NEAT. Whether this compensatory behaviour continues beyond the first month of an exercise program, particularly after training adaptations in cardiorespiratory fitness are realised, cannot be discerned from the current study. However these results do provide a rationale for why the magnitude of weight loss achieved is often less than predicted during exercise interventions. Further research is required to examine the temporal pattern of compensation in NEAT, and the relationship between the time courses of NEAT compensation relative to physical fitness improvements. The results from this thesis support the use of activity monitors such as accelerometers during weight loss interventions to track NEAT and provide objective feedback regarding compensatory behaviours to clinicians and the obese individuals.

Made available in DSpace on 2014-08-20T13:57:55Z (GMT). No. of bitstreams: 1 Tese_Felipe_Fossati_Reichert_parte_1.pdf: 38374 bytes, checksum: 5b8b2b63f3fda834f969b2df28aa7a06 (MD5) Previous issue date: 2008-07-15 / Background: Prospective studies on physical activity (PA), diet, and body composition in adolescents are lacking, particularly outside high-income countries. The aims of this paper were to describe the methods used for assessing these variables in the 1993 Pelotas (Brazil) Birth Cohort, and to discuss the fieldwork challenges faced and alternatives to overcome them. Methods: In 2006-7 a sub-sample of the 1993 Pelotas cohort was revisited. PA was estimated using questionnaires, a combined heart rate and motion sensor (Actiheart), and the Actigraph GT1M accelerometer. Diet was investigated by questionnaire. Total body water was determined by stable isotopes. Thirty individuals had their total energy expenditure assessed by double labeled water. All data were collected at participants home. Results: The logistics of the fieldwork and the difficulties in undertaking the study and alternatives to overcome them are presented. Preliminary analyses show that 511 individuals were traced (response rate = 90.0%). Compliance of both adolescents and their families for the motion sensors and body composition measurements was excellent. Conclusions: We conclude it is feasible to carry out high-quality studies on PA in developing countries. We hope the present manuscript will be useful to other researchers interested in carrying out similar studies. / Objetivos: Estudos prospectivos sobre a atividade física (AF), dieta e composição corporal em adolescentes são faltando, principalmente fora de países de alta renda. Os objetivos deste trabalho foram descrever os métodos utilizados para a avaliação dessas variáveis em 1993 Pelotas (Brasil) Birth Cohort, e discutir o trabalho de campo os desafios enfrentados e as alternativas para superá-los. Métodos: Em 2006-7 uma sub-amostra da coorte de Pelotas de 1993, foi revisitado. PA foi estimada utilizando questionários, uma frequência cardíaca combinado e sensor de movimento (Actiheart), ea actigráfico Acelerômetro GT1M. A dieta foi investigada por meio de questionário. Água corporal total foi de determinado por isótopos estáveis. Trinta indivíduos tiveram seu gasto energético total avaliada pela água etiquetada dupla. Todos os dados foram coletados em casa dos participantes. Resultados: A logística do trabalho de campo e as dificuldades em realizar o estudo e as alternativas para superar eles são apresentados. Análises preliminares mostram que 511 pessoas foram rastreados (taxa de resposta = 90,0%). Cumprimento de ambos os adolescentes e suas famílias para o sensores de movimento e medidas de composição corporal foi excelente. Conclusões: Concluímos que é viável realizar estudos de alta qualidade sobre a PA nos países em desenvolvimento. Esperamos que o manuscrito presente será útil para outros pesquisadores interessados em realizar estudos semelhantes.

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