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Title: The multi-directional relationships between physical activity and body composition and the development of COPD and its manifestations
Author: Pearson, Ruth
ISNI:       0000 0004 7970 8625
Awarding Body: Loughborough University
Current Institution: Loughborough University
Date of Award: 2018
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Introduction: This thesis explores the multidirectional relationships between physical activity, body composition and the development of Chronic Obstructive Pulmonary Disease (COPD) and associated risk factors for comorbidities through four different studies. Study 1: Sedentary behaviour, physical activity and relationships with cardiometabolic risk and body composition in COPD (SPAaRC Study). Introduction: People with COPD have a greater prevalence of cardiovascular disease and type II diabetes than the general population. It has been suggested that reduced levels of physical activity and greater sedentary behaviour might be responsible for this. A low body mass index (BMI) and lean mass is also related to increased mortality in COPD, which may also be affected by levels of physical activity. We aimed to investigate relationships between sedentary behaviour, physical activity, body composition and cardiometabolic risk factors in subjects with COPD and in older adult control subjects for comparison. Methods: Control participants were re-recruited from the Physical Activity and Respiratory Health Study (PhARoaH) study and COPD participants recruited from the PhARoaH study and from Leicester Respiratory outpatient clinics. Participants attended a single assessment visit where they answered questionnaires on their medical history, had blood specimens taken for fasting blood glucose, lipid profile (total cholesterol, low density lipoproteins (LDL), high density lipoproteins (HDL) and triglycerides), glycated haemoglobin A1c (HbA1c) and insulin and underwent physical measurements including BMI, spirometry, blood pressure and Dual Energy X-ray Absorptiometry for fat mass index and lean mass index measurement. Participants were provided with an accelerometer to measure physical activity over the subsequent 7 days. Regression models were used to assess the relationships as well as to model the effect of substituting sedentary time with both light activity and moderate/vigorous activity (MVPA). Results: 80 subjects were included in the analysis (29 controls (14 men, 51 with COPD (31 men), mean age was 68.1 years and forced expiratory volume in 1 second (FEV1) was 56.4% predicted in COPD men and 56.9% predicted in COPD women. There was a positive relationship between lean mass and all physical activity intensities, but no significant relationship was found between either sedentary time or physical activity and cardiometabolic risk factors in either COPD or control subjects. Conclusion: Both light activity and MVPA are associated with greater lean mass in COPD subjects, but a larger sample and longitudinal study is needed to further elucidate the relationship between physical activity, sedentary time and cardiometabolic risk. Study 2: Body mass index across adulthood and the development of airflow obstruction and emphysema. Introduction: Though there is an established association between low BMI and Chronic Obstructive Pulmonary Disease (COPD) the temporal relationship with structural and physiological changes within the lungs is unclear. This study examined the longitudinal changes in BMI, airflow obstruction (AO) and lung density throughout adulthood. Methods: BMI trajectories of participants in the Framingham Offspring Cohort from Exam 2 (n=3863 ,mean age=44), through Exam 9 (mean age=71), in those who developed Airflow Obstruction (AO) (n=1036, measured by spirometry), or low lung density (LLD) (n=225, measured by quantitative Computed Tomography), were modelled across adulthood using fractional polynomial growth curves and piece-wise linear splines. These were compared to smokers and non-smokers who did not develop these features. Tertiles of BMI in those aged below 40 years were then separately compared for the subsequent changes in lung function. Results: The pattern of BMI changes throughout adulthood in the AO group were similar to non-AO smokers and non-AO non-smokers, but lower across all ages from 30 years onwards. Subjects with low lung density on CT also had a lower BMI throughout adulthood compared to normal lung density smokers and non-smokers. Results from prediction models using piecewise linear splines of BMI throughout adulthood demonstrated that at age 35 years the AO group had a lower BMI than non-AO groups and the LLD had a lower BMI than non-LLD groups (AO: 24.7kg/m2 vs non-AO-smokers: 25.3kg/m2 vs non-AO-non-smokers: 25.9kg/m2 and LLD: 24.5 kg/m2 vs non-LLD-smokers: 26.0 kg/m2vs non-LLD-non-smokers: 24.7 kg/m2) Decline in FEV1/Forced vital capacity (FVC) ratio was steepest in the lowest BMI tertile in both sexes.Conclusion: These results suggest that mean BMI is lower throughout adulthood in those with subsequent airflow obstruction and low lung density. This, together with the finding that those with a lower BMI have a steeper decline in the ratio of FEV1/FVC, suggest body mass may have a role in COPD development. Study 3: Physical activity and the relationship with COPD and lung function changes. Introduction: Whilst physical activity is known to have a positive effect on health and is related to a reduction in hospitalisation and mortality in COPD it is unclear whether physical activity affects lung function decline. We examined the relationship between physical activity and age-related lung function decline in the Framingham Offspring Cohort. Methods: Multiple linear regression was used to examine the relationship between the Physical Activity Index (PAI) and its components in the sixth decade of life and the change in FEV1, FVC and the FEV1/FVC ratio over the subsequent decade. The cross-sectional relationship between objectively measured moderate/vigorous physical activity and FEV1 at Exam 9 was also examined using multiple linear regression. Results: There were 766 (men: 368) subjects in their sixth decade included in the analysis. A statistically significant positive relationship between the PAI and Heavy activity and FEV1 change and between the PAI, Moderate and Heavy was found in women, independent of smoking, but not in men. There was also a statistically significant positive relationship between cross-sectional objectively measured moderate/vigorous activity and FEV1 in women, but this was again not found in men. Conclusion: The positive relationship found between self-reported physical activity and lung function change together with the finding of a positive relationship between objectively measured moderate/vigorous activity and FEV1 at Exam 9 suggests that increasing Heavy activity may be associated with reduced lung function decline and play a role in prevention of COPD in women. Study 4: The influence of muscle mass in the assessment of lower limb strength in COPD. Introduction: Quadriceps Maximal Voluntary Contraction (QMVC) measurement provides functional and prognostic information in COPD. Establishment of a prediction equation would aid therapeutic decision making and assessment of outcomes. Whether including a measure of muscle mass within predictions influences the classification of weakness is unclear. Prediction equations with and without a measure of muscle mass derived in healthy adults are presented and their assessment of QMVC in two different COPD cohorts is compared.Methods: Prediction equations for QMVC were derived in healthy adults. Age, gender, height and weight entered in the first model (FFM-), and total body fat-free mass added for the second (FFM+). Percent predicted values and frequency of weakness were compared in Primary Care and Complex Care COPD cohorts. Results: Subjects: 175 Healthy Controls: (median (IQR): 54 (14) years, 31% male); 102 Primary Care: 68 (9) years, 66% male, FEV1 66.1 (25)% predicted); and 189 Complex Care: 66 (12) years, 57% male, FEV1: 29 (16)% predicted). R2 values were similar for FFM- and FFM+ in controls (0.60, 0.59), as were mean %predictions in Primary Care patients (88.3% vs 88.8%). In Complex Care %predictions were 5.2% higher with 11.9% fewer classified weak with FFM+. Conclusion: Inclusion of fat-free mass in QMVC prediction equations has little influence in healthy adults but results in lower prevalence of weakness in COPD, particularly in the Complex Care Cohort. Our findings support the use of an equation without fat-free mass for strength assessment, but its inclusion may characterise the functional deficit in the presence of low muscle mass. Conclusion to thesis: Physical activity levels may be related to cardiometabolic risk and body composition in COPD. In addition body mass and physical activity may play a role in disease development itself. The prescription of physical activity may assist in achieving optimal body composition, reducing lung function decline and improving cardiometabolic profile in individuals with or at risk of developing COPD.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Medical and Health Sciences not elsewhere classified ; COPD Chronic Obstructive Pulmonary Disease ; Physical Activity ; body composition ; Comorbidities ; cardiometabolic health risks ; quadriceps strength