published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

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The increasing evidence of associations between physical activity, sedentary behaviour, sleep duration and diet and both immediate and long term health implications is of public health concern. There is a need to further our understanding of the patterns of these behaviours and how they affect poor health indicators individually and simultaneously. This thesis aims to advance the current literature by investigating associations between multiple lifestyle behaviours and indicators for poor health and identifying patterns of physical activity, sedentary behaviour, sleep duration and dietary intake. Anthropometric measurements and bioelectrical impedance analysis were collected from 72 UK adults. These participants were asked to wear an ActiGraph GT1M accelerometer to objectively measure their physical activity and sedentary behaviour across 7 consecutive days. Over these 7 days, participants also completed a self-report daily sleep diary and a food frequency questionnaire. Participants were asked to complete these measurements at 4 different time points across the year in order to capture these behaviours over each season; 46 participants completed all 4 seasons. Using the data collected from the 72 participants who completed at least 1 season, regression analyses were conducted to identify associations between lifestyle behaviours and indicators for poor health. Repeated measures ANOVAs were conducted on data from 52 participants who provided the full 7 days of data during their initial measurement period to assess day of the week variations in physical activity, sedentary behaviour and sleep patterns. Repeated measures ANOVAs were also conducted on physical activity, sedentary behaviour, sleep and dietary intake data provided by the 46 participants who provided 4 seasons of data to assess seasonal variation. This thesis demonstrated that in a sample of relatively active, UK adults, time spent in moderate-vigorous physical activity and sedentary behaviour had a negative association with BMI and body fat percentage, increased time spent in moderate-vigorous physical activity was also associated with decreases in waist circumference. Light intensity physical activity had a positive association with BMI, body fat percentage and diastolic blood pressure. There were significant day of the week variations in light intensity physical activity, sedentary behaviour and time spent in bed, with light intensity physical activity and time in bed being significantly higher on a Sunday, whilst sedentary behaviour was significantly lower on a Sunday in this sample of UK adults. In addition to day of the week variations, there were seasonal variations in light intensity physical activity, sedentary behaviour and time spent in bed and sleep durations (weekdays only). Over the winter months, light intensity physical activity was significantly lower, whilst sedentary behaviour, time in bed and total sleep time was significantly higher. No seasonal variations in time spent in moderate-vigorous intensity physical activity or diet were observed in the present sample. This thesis demonstrates that lifestyle behaviours that have been found to affect health do vary over the week and across different seasons. This research has implications for surveillance studies which estimate these behaviours at one time point throughout the year, and also for interventions aimed at improving these behaviours which are implemented at just one time period of the year. Strategies for overcoming barriers to PA under unfavourable environmental conditions will be needed for this to be achieved, in addition to interventions reducing SB, even in the winter months.

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Obesity and diet-associated chronic illnesses are a major burden on the health of the U.S. population. Healthcare providers are challenged with the treatment of patients with chronic illness but are not equipped to manage and influence patient lifestyle choices. Effective, long-term behavior change using interventions such as a dietary program can be costly and time consuming. Pioneer Comprehensive Medical (PCM) is a small clinic located in Draper, Utah that uses a dietary intervention program to improve patient health, but program application is inconsistent, patients feel ill equipped to make changes, and attrition is high. Like many small clinics, PCM has limited resources to adopt new policies and programs. This practice inquiry (PI) proposes to address this practice gap with behavior change theory as a foundation (Chapter 1) and improving the program at PCM with a quality improvement (QI) process using a Plan-Do-Study-Act (PDSA) model. In the "Plan" phase (Chapter 2), a systematic review of the research literature determined the key components for effective dietary interventions. Six characteristic features found in these interventions include: self-efficacy building education, web-based delivery, sequential delivery of information, consistent messaging with reminders, a supportive social environment and individually-tailored feedback. The "Do" phase (Chapter 3) is the design of a program delivery method that incorporates the findings from the literature. The "Study" phase (Chapter 4) is the design of a pilot study to assess the usability, feasibility, and sustainability of the program. The "Act" phase (Chapter 5) is the implementation plan for all PCM patients based on findings in the pilot study and to assess the impact of the program. This final phase will provide detailed data to assess the short, intermediate, and long-term outcomes of the program.

This Ph.D. dissertation presents results that shed light on whether there is an association between dietary intake and depressive disorder, feelings of sadness, or thoughts of death. This question is investigated in the context of a secondary data analysis using cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) 1999-2002. Subjects in this study were identified as a subpopulation of the NHANES survey that completed the Composite International Diagnostic Interview questionnaire for major depression. The presence of depression may lead to a decline in dietary intake and nutritional status. Conversely, poor dietary intake may have a role in the etiology of depression. Specifically, depression is associated with lower plasma, erythrocyte, phospholipid, and adipose tissue omega-3 fatty acids. Little is known about the comprehensive dietary intake of those with depression or depressive symptoms. Initially, comparisons of the dietary profile between those with and without depression or depressive symptoms were investigated. Secondly, analysis was done to determine the relationship between dietary omega-3 fatty acids and depression or depressive symptoms. Lastly, to clarify the relationship between diet and depression, misreporting of dietary energy intake was evaluated.No significant differences in the dietary profile or nutritional biochemistries were found between the altered mood and normal mood groups. No significant differences were found in dietary omega-3 fatty acids between the depressed and non-depressed groups, even after adjusting for confounding variables. Misreporting of energy intake was not significantly associated with altered mood status and remained non-significant after adjusting for confounding variables. In both groups, a significant decreasing trend in the ratio of energy intake to estimated basal metabolic rate (EI:BMRest) was found as body mass index increased.Based on dietary intake alone, the relationship between depression and specific nutrients may not be apparent. Dietary intake among those with depression and depressive symptoms appears to be adequate, but adequacy may not be sufficient as a route for prevention or management of depression. Further investigation of diet and depression ought to measure diet, including nutrition supplements, and biochemical levels of nutrients from a broader age range of adults and children and those with comorbid illnesses.

Prior research has suggested that life style factors, such as diet and physical activity, influence prostate cancer (PCa) progression. Metformin intake has been shown to be associated with decreased cancer risk in type II diabetic patients. We hypothesize that a low carbohydrate diet, prolonged aerobic exercise and metformin treatment can all independently slow prostate tumor development and a combination regimen will have an additive benefit. We used LNCaP xenografts to test this hypothesis. Results revealed that a diet low in carbohydrate reduced food consumption and a combination with exercise significantly reduced animal body weights. Ten weeks of metformin did not significantly alter tumor growth rate compared to control animals. Ten weeks of exercise significantly inhibited tumor growth. Out results suggest that dietary carbohydrate alteration or the administration of metformin alone cannot significantly influence prostate tumor progression. A suitable sustained exercise regimen may offer a more protective effect against PCa progression.

Prior research has suggested that life style factors, such as diet and physical activity, influence prostate cancer (PCa) progression. Metformin intake has been shown to be associated with decreased cancer risk in type II diabetic patients. We hypothesize that a low carbohydrate diet, prolonged aerobic exercise and metformin treatment can all independently slow prostate tumor development and a combination regimen will have an additive benefit. We used LNCaP xenografts to test this hypothesis. Results revealed that a diet low in carbohydrate reduced food consumption and a combination with exercise significantly reduced animal body weights. Ten weeks of metformin did not significantly alter tumor growth rate compared to control animals. Ten weeks of exercise significantly inhibited tumor growth. Out results suggest that dietary carbohydrate alteration or the administration of metformin alone cannot significantly influence prostate tumor progression. A suitable sustained exercise regimen may offer a more protective effect against PCa progression.