The relative importance of abiotic versus biotic top-down factors on structuring tundra plant communities is debated. With climate change already strongly affecting the tundra ecosystem, understanding which factors will prevail is vital. Tundra plant communities are presumed to be predominantly structured by their abiotic conditions yet grazing by reindeer (Rangifer tarandus) has a major effect on composition and diversity. It is increasingly recognized, however, that these factors cannot be considered in isolation. Here, I aim to test the relative and interactive effect of abiotic and top- down factors on vegetation structure in the Swedish mountain tundra. Using direct measurements of reindeer grazing via tri-axial accelerometers (from two summers, 2019 and 2020) coupled with remotely-gathered data on landscape features, I examine how species richness and coverage of vascular plants, bryophytes and lichens (sampled in 2022) are driven by grazing duration and abiotic conditions. Abiotic factors, specifically aspect and soil wetness, prevailed as the dominant drivers of local vegetation patterns. Clear interactions between factors were also observed. Reindeer grazing duration had predictable but weak effects on richness, with responses predominantly observed on south-facing slopes. Additionally, soil wetness interacted with grazing duration, with wetter areas grazed far less. These results demonstrate the importance of considering interactions between abiotic and biotic factors, providing a better understanding of how tundra plant communities in northern Sweden might change under future climate change or different grazing regimes. The observed interactions imply divergence in vulnerability between slopes and the potential for effects of herbivory to be altered under future hydrological conditions. I emphasize that future studies should continue to disentangle these relationships.

Objective: The diagnosis of delirium in intensive care unit patients is frequently missed. Key symptoms to identify delirium are motoric alterations, changes in activity level, and delirium-specific movements. This study aimed to explore features collected by a single wrist-worn accelerometer as indicators of delirium. Methods: The study included twenty-two patients in the intensive care unit. The data was collected with the GENEActiv accelerometer device and the activity level was calculated. Differences between the delirious and nondelirious patients were tested. Results: Differences in activity level and rest-activity patterns were noticed between the delirious and non-delirious patients. However, the differences were not found to be significant. Conclusion: Activity patterns revealed differences between delirious and non‐delirious patients. Further study is required to confirm the potential of actigraphy in the early detection of delirium in the intensive care unit. / Mål: Diagnosen delirium hos intensivvårdspatienter missas ofta. Nyckelsymptom för att identifiera delirium är motoriska förändringar, förändringar i aktivitetsnivå och deliriumspecifika rörelser. Denna studie syftade till att utforska funktioner som samlats in av en enskild handledsburen accelerometer som indikatorer på delirium. Metod: Studien omfattade tjugotvå patienter på intensivvårdsavdelningen. Data samlades in med GENEActiv accelerometerenheten och aktivitetsnivån beräknades. Skillnader mellan de delirious och icke-delirious patienterna testades. Resultat: Skillnader i aktivitetsnivå och viloaktivitetsmönster noterades mellan de deliriösa och icke-deliriösa patienterna. Skillnaderna visade sig dock inte vara signifikanta. Slutsats: Aktivitetsmönster avslöjade skillnader mellan deliriösa och ickedelirösa patienter. Ytterligare studier krävs för att bekräfta potentialen för aktigrafi vid tidig upptäckt av delirium på intensivvårdsavdelningen.

No description available.

Motor competence is positively associated with physical activity and health-related fitness (HRF) across childhood and adolescence. Owing to their motor difficulties, children with Developmental Coordination Disorder (DCD) are found to have poorer HRF and lower activity levels compared to typically developing (TD) children. It is thought that children with DCD are less physically fit due in part to hypoactivity; however, it is still unclear how young these deficits emerge, or if physical activity explains these HRF differences. This thesis aims to fill these gaps by examining physical activity and HRF in preschool children with and without DCD, and testing mediation models linking motor competence to HRF through physical activity engagement, both cross-sectionally and over time from preschool to school age. The first and second studies demonstrated that preschool children with DCD exhibit poorer musculoskeletal and aerobic fitness compared to TD children, however physical activity engagement was similar and did not explain these fitness deficits. The third study found that the relationship between motor competence and physical activity was not significant at preschool age, but emerged over time as children reached school age. Additionally, motor competence was a significant positive predictor of musculoskeletal fitness across the early years, again largely independent of physical activity levels. This thesis represents the first comprehensive series of studies that examines objectively-measured motor competence, physical activity and HRF in large samples of preschool-age children both with and without DCD. These studies highlight that poor motor competence is a risk factor for poor physical fitness, irrespective of physical activity in the early childhood period. Early motor interventions may positively influence physical fitness and may help to prevent the declines in physical activity observed as children with DCD reach middle childhood and adolescence. / Thesis / Doctor of Philosophy (PhD) / Children with motor coordination difficulties are more likely to be unfit and inactive compared to typically developing (TD) children. However, it is still not understood when these problems emerge, or if inactivity explains why children with motor difficulties are less physically fit. This thesis examines the links between motor competence, physical activity, and fitness in two large cohorts of preschool-age children. Results show that young children with motor difficulties are less physically fit, but are not less active than TD children. In addition, children with better motor skills become more active as they get older. Despite similar physical activity levels at preschool age, these findings highlight that poor motor abilities in early childhood are a risk factor for poor physical fitness and future inactivity. Interventions targeting motor skills in the early years may help children stay active and healthy as they age.

Solar radiation pressure (SRP) is one of the major non-gravitational forces acting on spacecraft. Acceleration by radiation pressure depends on the radiation flux; on spacecraft shape, attitude, and mass; and on the optical properties of the spacecraft surfaces. Precise modeling of SRP is needed for dynamic satellite orbit determination, space mission design and control, and processing of data from space-based science instruments. During Earth penumbra transitions, sunlight is passing through Earth's lower atmosphere and, in the process, its path, intensity, spectral composition, and shape are significantly affected. This dissertation presents a new method for highly physical SRP modeling in Earth's penumbra called Solar radiation pressure with Oblateness and Lower Atmospheric Absorption, Refraction, and Scattering (SOLAARS). The fundamental geometry and approach mirrors past work, where the solar radiation field is modeled using a number of light rays, rather than treating the Sun as a single point source. This dissertation aims to clarify this approach, simplify its implementation, and model previously overlooked factors. The complex geometries involved in modeling penumbra solar radiation fields are described in a more intuitive and complete way to simplify implementation. Atmospheric effects due to solar radiation passing through the troposphere and stratosphere are modeled, and the results are tabulated to significantly reduce computational cost. SOLAARS includes new, more efficient and accurate approaches to modeling atmospheric effects which allow us to consider the spatial and temporal variability in lower atmospheric conditions. A new approach to modeling the influence of Earth's polar flattening draws on past work to provide a relatively simple but accurate method for this important effect. Previous penumbra SRP models tend to lie at two extremes of complexity and computational cost, and so the significant improvement in accuracy provided by the complex models has often been lost in the interest of convenience and efficiency. This dissertation presents a simple model which provides an accurate alternative to the full, high precision SOLAARS model with reduced complexity and computational cost. This simpler method is based on curve fitting to results of the full SOLAARS model and is called SOLAARS Curve Fit (SOLAARS-CF). Both the high precision SOLAARS model and the simpler SOLAARS-CF model are applied to the Gravity Recovery and Climate Experiment (GRACE) satellites. Modeling results are compared to the sub-nm/s^2 precision GRACE accelerometer data and the results of a traditional penumbra SRP model. These comparisons illustrate the improved accuracy of the SOLAARS and SOLAARS-CF models. A sensitivity analyses for the GRACE orbit illustrates the significance of various input parameters and features of the SOLAARS model on results. The SOLAARS-CF model is applied to a study of penumbra SRP and the Earth flyby anomaly. Beyond the value of its results to the scientific community, this study provides an application example where the computational efficiency of the simplified SOLAARS-CF model is necessary. The Earth flyby anomaly is an open question in orbit determination which has gone unsolved for over 20 years. This study quantifies the influence of penumbra SRP modeling errors on the observed anomalies from the Galileo, Cassini, and Rosetta Earth flybys. The results of this study prove that penumbra SRP is not an explanation for or significant contributor to the Earth flyby anomaly. / Ph. D.

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

<p>Syfte</p><p>Syftet med studien är att undersöka om det finns ett samband mellan motorisk färdighet ochmängd fysisk aktivitet av olika intensiteter hos barn med diagnosen ADHD.</p><p>Frågeställningar</p><p>1. Hur många barn med ADHD har motoriska nedsättningar utifrån Movement ABC?</p><p>2. Hur många barn med ADHD når upp till de Nordiska rekommendationerna för fysiskaktivitet?</p><p>3. Hur ser sambandet mellan motorisk färdighet och fysisk aktivitetsnivå ut hos barn medADHD?</p><p>Metod</p><p>I studien ingick fem pojkar i åldern 9-12 år med diagnosen ADHD. I studien mättes denfysiska aktivitetsgraden med accelerometrar av modellen ActiGraph GT3X somtestpersonerna bar under sju efterföljande dagar. Den motoriska förmågan hos testpersonernamättes med hjälp av de kvantitativa motoriktesterna i Movement ABC. Testerna genomfördesi en lokal på testpersonernas skolor och accelerometrarna samt ett medföljandeinformationsbrev delades ut vid samma tillfälle.</p><p>Resultat</p><p>Av resultaten av motoriktesterna framgår att endast en testperson hade ett resultat som visarpå tillfredsställande motorisk förmåga, tre testpersoner låg i riskzonen för motoriskanedsättningar och en testperson hade uppenbara brister i sin motoriska färdighet. Fyra av de fem testpersonerna uppnådde de Nordiska rekommendationerna om minst 60 minuters fysiskaaktivitet per dag, inkluderad både måttlig till hård aktivitet. Inga signifikanta samband kundeses mellan fysisk aktivitetsnivå och motorisk färdighet.</p><p>Slutsats</p><p>Studien kunde inte finna något samband mellan motorisk färdighet och mängd fysisk aktivitetav olika intensiteter hos barn med diagnosen ADHD. På grund av testgruppens ringa storlekbör man ej betrakta studiens resultat som generaliserbara, studien kan dock ses som enpilotstudie.</p> / <p>Aim</p><p>The purpose of this study was to investigate whether there is a correlation between motorskills and amount of physical activity of various intensities in children diagnosed with ADHD.</p><p>Questions</p><p>1. How many children with ADHD have motor impairments based on Movement ABC?</p><p>2. How many children with ADHD reaches the Nordic recommendations for physicalactivity?</p><p>3. What is the relationship between motor skills and level of physical activity in childrenwith ADHD?</p><p>Method</p><p>The study included five boys aged 9-12 years diagnosed with ADHD. The study is study inwhich the physical activity level was measured using ActiGraph GT3X accelerometers whichtest subjects wore for seven subsequent days. The motor skills of the test subjects were measured using the quantitative motor tests in Movement ABC. The tests were carried out ina room at the test subjects schools and accelerometers, and accompanying instruction were distributed at the same time.</p><p>Results</p><p>The results of motor tests showed that only one person had test results showing satisfactorymotor skills, three test persons were at risk of motor impairments and a test person hadobvious defects in their motor skills. Four of the five test persons achieved the nordicrecommendations for at least 60 minutes of physical activity per day, including both moderateto heavy activity. No significant correlation was seen between physical activity level andmotor skills.</p><p>Conclusions</p><p>The study could not find any correlation between motor skills and amount of physical activityof various intensities in children diagnosed with ADHD. Due to the small test group theresults of the current study should be taken with precaution, but can be regarded as a pilotstudy.</p>

Syfte Syftet med studien är att undersöka om det finns ett samband mellan motorisk färdighet ochmängd fysisk aktivitet av olika intensiteter hos barn med diagnosen ADHD. Frågeställningar 1. Hur många barn med ADHD har motoriska nedsättningar utifrån Movement ABC? 2. Hur många barn med ADHD når upp till de Nordiska rekommendationerna för fysiskaktivitet? 3. Hur ser sambandet mellan motorisk färdighet och fysisk aktivitetsnivå ut hos barn medADHD? Metod I studien ingick fem pojkar i åldern 9-12 år med diagnosen ADHD. I studien mättes denfysiska aktivitetsgraden med accelerometrar av modellen ActiGraph GT3X somtestpersonerna bar under sju efterföljande dagar. Den motoriska förmågan hos testpersonernamättes med hjälp av de kvantitativa motoriktesterna i Movement ABC. Testerna genomfördesi en lokal på testpersonernas skolor och accelerometrarna samt ett medföljandeinformationsbrev delades ut vid samma tillfälle. Resultat Av resultaten av motoriktesterna framgår att endast en testperson hade ett resultat som visarpå tillfredsställande motorisk förmåga, tre testpersoner låg i riskzonen för motoriskanedsättningar och en testperson hade uppenbara brister i sin motoriska färdighet. Fyra av de fem testpersonerna uppnådde de Nordiska rekommendationerna om minst 60 minuters fysiskaaktivitet per dag, inkluderad både måttlig till hård aktivitet. Inga signifikanta samband kundeses mellan fysisk aktivitetsnivå och motorisk färdighet. Slutsats Studien kunde inte finna något samband mellan motorisk färdighet och mängd fysisk aktivitetav olika intensiteter hos barn med diagnosen ADHD. På grund av testgruppens ringa storlekbör man ej betrakta studiens resultat som generaliserbara, studien kan dock ses som enpilotstudie. / Aim The purpose of this study was to investigate whether there is a correlation between motorskills and amount of physical activity of various intensities in children diagnosed with ADHD. Questions 1. How many children with ADHD have motor impairments based on Movement ABC? 2. How many children with ADHD reaches the Nordic recommendations for physicalactivity? 3. What is the relationship between motor skills and level of physical activity in childrenwith ADHD? Method The study included five boys aged 9-12 years diagnosed with ADHD. The study is study inwhich the physical activity level was measured using ActiGraph GT3X accelerometers whichtest subjects wore for seven subsequent days. The motor skills of the test subjects were measured using the quantitative motor tests in Movement ABC. The tests were carried out ina room at the test subjects schools and accelerometers, and accompanying instruction were distributed at the same time. Results The results of motor tests showed that only one person had test results showing satisfactorymotor skills, three test persons were at risk of motor impairments and a test person hadobvious defects in their motor skills. Four of the five test persons achieved the nordicrecommendations for at least 60 minutes of physical activity per day, including both moderateto heavy activity. No significant correlation was seen between physical activity level andmotor skills. Conclusions The study could not find any correlation between motor skills and amount of physical activityof various intensities in children diagnosed with ADHD. Due to the small test group theresults of the current study should be taken with precaution, but can be regarded as a pilotstudy.

Syfte. Syftet med studien var att med accelerometri kartlägga det fysiska aktivitetsmönstret hos äldre vid två separata förtest och i slutet av en tvåmånadersperiod med ledarledd träning två gånger per vecka. En vidare målsättning var att studera överensstämmelsen mellan enkätfrågorna om fysisk aktivitet och stillasittande gentemot uppmätt accelerometer­data. Metod. En grupp 65-91 år (medel 71 år, BMI 25 kg/m2) studerades. Två förtest (F1 &amp; F2) samt ett efter­test (E) utfördes under sista träningsveckan. Totalt ingick 97 individer vid F1 &amp; F2 samt 78 vid E som jämfördes mot resultat vid F2. Resultat. Vid F1 sågs vid accelerometri för minst måttlig fysisk ak­tivitet medelvärdet 42,7 min/d (MVPA/d), men endast 22, 2 min/d för tid i perioder à minst 10 min (Freedson bouts/d). Vid analys av separata dagar kom bara 15% av deltagar­na upp till rekommenderade 5 dgr/v à minst 30 min av sammanhängande 10-min-perioder fysisk aktivitet (med lägst måttlig intensitet). Median för högintensiv aktivitet (VPA) var mycket låg för denna grupp (0,9 min/d). Medel för stillasittande var 10,2 timmar (SED/d) samt 4,3 timmar total tid i minst 20-min-perioder (Sedentary bouts/d). Mellan F1 &amp; F2 sågs ingen signifikant förändring för MVPA/d eller Freedson bouts/d. Däremot fram­kom en ytterst liten sänkning som var signifikant för stillasittande tid (20,0  resp. 13,7 min/d i SED/d resp. Sed bouts/d). Förändring av VPA visade en minimal ökning med 0,4 min/d (sign.). Korrelationen mellan F1 &amp; F2 var 0,86 för MVPA/d, 0,81 för Freedson/d, 0,59 för Vig/d, 0,59 för SED/d samt 0,74 för Sed bouts/d, alla signifikanta. Vid E sågs, gentemot F2, en liten men signifikant ökning av medel för MVPA/d (till 50,6 min/d), men inte för Freedson bouts (20,9 min/d) eller för målet minst 5 dgr/v med 30 min i Freedson bouts/d (12%). Stillasittande sjönk signifikant för E till 9,7 tim/d (SED/d) samt 3,6 tim/d (Sed. bouts/d). VPA ökade minimalt med 0,5 min/d (sign.) till medianvärdet 1,7 min/d. De starkaste signifikanta (*) korrelationerna mellan olika frågor och accelerometri noterades för MVPA/d resp. Freedson bouts/d (som mest 0.53- 0,60*), följt av stillasittande 0,40* resp. 0,39* (i SED/d resp. Sed bouts/d). För VPA noterades inga eller ytterst låga samband, som högst r=0,24* mot frågorna. Slutsats. Värdena för högintensiv aktivitet vid accelerometri visade genomgående förvånansvärt låga nivåer. En orsak kan vara att datoranalysprogrammen för aktivitetsmätarna inte är tillräckligt känsliga såsom de idag är inställda för seniorers högsta intensitetsnivåer. Bäst signifikanta samband gentemot accelerometri sågs för frågor om minst måttligt intensiv fysisk aktivitet. Visst signifikant samband sågs även för en fråga om stillasittande, medan aktivitetsmätarens data stämde vanligtvis inte överens med självskattad data för högintensiv fysisk aktivitet för äldre. Så dessa seniordata är inte helt lika jämfört med tidigare studier på yngre vuxna som vanligtvis visat en högre validitet för frågor med högintensiv jämfört med måttligt intensiv fysisk aktivitet. / Aim. The purpose of the study was to identify that with accelerometry the physical activity patterns of elderly, at two separate pre-test and at the end of a two-month period with instructor-led training twice per week. A further aim was to study the correlation between survey questions about physical activity and sedentary against measured accelerometer data. Method. A group of 65-91 years (mean 71 years, BMI 25 kg/m2) were studied. Two pre-test (F1 &amp; F2) and an aftertest (E) was performed during the last training week. A total of 97 individuals at F1 &amp; F2 and 78 at E compared to F2 were investigated. Results. In F1 was seen for accelerometer data (at least moderate physical activity) mean values 42.7 min/d (MVPA/d), but only 22,2 min/d in time periods of at least 10 minutes (Freedson bouts /d). In the analysis of separate days came only 15% of participants came up to the recom­men­ded 5 days/week with at least 30 minutes of continuous 10-min periods of physical activity (with at least moderate intensity). Vigorous intensity activity (VPA) was very low for this group (0.9 min/d). The average for sedentary time was 10.2 hours (SED/d) and 4.3 hours total time in 20-min periods (Sedentary bouts/d). Between F1 and F2 no significant changes were seen for MVPA/d or Freed­son bouts/d. A tiny reduction, which was significant, was seen for sedentary time (20.0 resp. 13.7 min/d SED/d, resp. Sed bouts/d). Change of VPA showed a minimal increase of 0.4 min/d (s.). The correlation between F1 &amp; F2 was 0.86 for MVPA/d, 0.81 for Freedson/d, 0.59 for Vig/d, 0.59 SED/d and 0.74 for Sed bouts/d, all significant. At E emerged, against F2, a small but significant increase for MVPA/d (to 50.6 min/d), but not for Freedson bouts/d (20.9 min/d) or to target at least 5 days/week with 30 min in Freedson bouts/d (12%). Sedentary fell significantly for E to 9.7 h/d (SED/d) and 3.6 h/d (Sed. bouts/d). VPA increased minimally by 0.5 min/d (s.) to median 1.7 min/d. The strongest significant (*) correlations between different questions and the accelerome­ters was noted for MVPA/d, resp. Freedson bouts/d (at most 0.53-0.60 *), followed by sedentary time 0.40 * resp. 0.39 * (in SED/d resp. Sed bouts/d). VPA showed no or very low correlation (highest r = 0.24 *) to the questions. Conclusion. The values ​​of vigorous activities in accelerometer data consistently showed surprisingly low levels. One reason may be that the computer analysis programs for the activity counters are not sufficiently sensitive as they currently are set for senior´s highest intensity levels. Best significant correlation against the accelerometers was seen for questions about at least moderately intense physical activity. Some significant correlation was also seen for sedentary time, while accelerometer data was generally not consistent with self-reported data for high-intensity physical activity for older people. So these senior data show somewhat different results as compared to previous studies in younger adults who usually present a higher validity of the questions with high-intensity compared with moderate-intensity physical activity.

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.