Prevalence of obesity, low physical activity, and poor physical fitness of youth in the United States are increasingly poor and in need of intervention to prevent later concerns like hypertension. The overall goal of this dissertation was to examine which factors weigh heaviest in predicting cardiovascular fitness in diverse youth, and how we might measure those factors by maximizing clinical utility and psychometric properties. The sample was gathered from a larger study examining physical activity in youth from Miami-Dade county enrolled in out-of-school programs. Participants (N = 58) were aged 6-17 and comprised exclusively of Hispanic and Non-Hispanic Black children and adolescents, the majority of whom were from low-income families. Predictors of fitness were gathered in three primary categories: demographic variables (age, gender, race/ethnic category, family income level), body composition (Body Mass Index [BMI] percentile, Bioelectrical Impedance Analysis [BIA]-measured body fat percentage), and habitual physical activity (accelerometer-measured counts per minute). These factors were entered in a hierarchical regression model to predict cardiorespiratory fitness measured by performance on a 20-meter shuttle run. Physical activity was not found to be significantly associated with fitness, and the effect size of this relationship was small, particularly when considering the impact of demographic and body composition variables. Overall, results reinforced the need for interventions to improve body composition and increase physical activity: the average participant was at the 81st percentile of BMI, had 26% body fat, was sedentary for approximately 84% of awake time, and only spent a few minutes per day engaging in vigorous physical activity. There were significant main effects of gender and race/ethnic category such that males and Non-Hispanic Black participants generally spent a greater proportion of time engaging in physical activity, with less sedentary time. Being female, younger, and having less body fat was associated with performance in the healthy fitness range when considering the impact of other variables, even though boys and older participants had more laps on the shuttle run. Findings presented in this dissertation indicate a continued need to develop technology with high utility, validity, and reliability to measure and improve indicators of health in diverse, low-income youth.

Indiana University-Purdue University Indianapolis (IUPUI) / Efforts to encourage the medical community to prescribe exercise for disease prevention and management have increased significantly in recent years. In patients with obstructive sleep apnea (OSA), it is encouraging that exercise has been shown to improve sleep efficiency, daytime sleepiness, and disease severity. However, in order to better understand the dose-response relationship between exercise and OSA-related outcomes, accurate and reliable methods for assessing physical activity habits are needed. Purpose: To determine the test-retest reliability and validity of two self-report physical activity questionnaires [Physical Activity Vital Sign (PAVS); International Physical Activity Questionnaire-Short Form (IPAQ-SF)] in an OSA population. Methods: 39 adults with moderate-to-severe OSA wore an accelerometer for seven consecutive days and completed the PAVS and IPAQ-SF (twice within 10 d), along with questionnaires on quality of life, sleepiness, and treatment adherence. Test-retest reliability was determined using intraclass correlation coefficients (ICC). Criterion and construct validity were determined using Pearson (r) and Spearman correlation coefficients (ρ), respectively. Results: PAVS and IPAQ-SF scores were reported as total min/wk of moderate-vigorous physical activity (MVPA). Test-retest reliability for MVPA was excellent for PAVS (ICC = 0.982) and good for IPAQ-SF (ICC = 0.766). MVPA assessed via accelerometry was strongly correlated with PAVS (r = 0.802) and moderately with IPAQ-SF (r = 0.569). Both PAVS and IPAQ-SF were significantly correlated with body mass index (BMI) (ρ = -0.273 and -0.268, respectively), but no other variables. Conclusions: The PAVS and IPAQ-SF are reliable and valid PA questionnaires and may be utilized as a tool for accurately assessing physical activity levels in OSA patients.

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Master's thesis "Segmental evaluation of standing posture using accelerometers" is focused on assessment of relationships between body segments during quiet standing with varied sensory afferentation according to CTSIB test. Theoretical part reviews prevailing theoretical work regarding posture, stability, equilibrium and balance and discusses the possibilities of posture assessment with accent on accelerometry and jerk based metrics. The objective of experimental part is to discover influence of sensory afferentation on following aspects: acceleration and jerk of body segments (head, thorax, sacrum and shins); linear correlation of acceleration between body segments; linear correlation of jerk between body segments; jerk magnitude ratio of individual segments. The results demonstrate increasing jerk of sacrum and shins with more demanding postural condition. Jerk linear correlations vary from 0,05 to 0,3 which contradicts the simple inverted pendulum hypothesis of body movement during quiet standing. Higher correlations are registered in the standing on the foam surface compared to firm surface. This relation is accentuated while standing with closed eyes. Higher correlations suggest increasing tendency to the single segment strategy. All above mentioned data are statistically significant. Jerk of...

A better understanding of the association of the environment to young children's physical activity is needed to design effective behavioral interventions and to improve communities' infrastructures in ways that support the development of healthy behaviors. This thesis used data from the Iowa Bone Development Study (IBDS) to examine activity behaviors of young children in urban and rural Iowa. Mean daily minutes of moderate through vigorous physical activity (MVPA) and vigorous physical activity (VPA), as recorded by accelerometry-based physical activity monitoring in the IBDS, were compared by level of socioeconomic status (SES) and census block type (urban or rural). Media use (television and videogames), in hours per day by parental report, was similarly compared. Logistic regression was used to assess the association of census block type (urban or rural) with lower categories of MVPA and VPA, and with a high category of media use (exceeding the American Academy of Pediatrics (AAP) recommendation for ≤ 2 hours/day of media). Mean age of the 400 participants included in this thesis was 5.65 years (SD = 0.53), females comprised 53.5%. Children's mean daily minutes of MVPA and VPA were not significantly different among SES levels nor between urban and rural census blocks. Rural children had decreased odds for lower categories of MVPA (Boys' OR 0.91; 95% CI: 0.51, 1.60) (Girls' OR 0.89; 95% CI: 0.53, 1.50) and VPA (Boys' OR 0.84; 95% CI: 0.48, 1.48) (Girls' OR 0.90; 95% CI: 0.54, 1.52), but not significantly so. Lower SES boys and girls engaged in more daily media use (hours/day) than higher SES children, and a higher proportion of low SES children exceeded the AAP recommendation than did middle-level or high SES children. Rural boys' media use (2.7 hours/day) was higher than that of urban boys (2.3 hours/day) (95% CI: 0.06, 0.80 hours/day), whereas urban and rural girls' media hours/day were not significantly different. Odds for excess media use were higher for rural boys (OR 2.11; 95% CI: 1.14, 3.11) and for low SES boys (OR 2.99; 95% CI: 1.34 6.68), as well as for low SES girls (OR 4.12; 95% CI: 1.95, 8.71). Although rural and urban children's MVPA and VPA did not differ in this thesis, rural and low SES boys had both higher daily media hours and increased odds for exceeding AAP media recommendations. Odds for excess media also were increased for low SES girls. Interventions to improve healthy behaviors of young children by limiting screen-based recreation and/or supplying means for alternate activity and play opportunities may be especially beneficial when focused on lower SES and rural areas.

Advances in electronic sensor technologies have led to the increased use of accelerometers for measuring physical activity and sedentary behaviours. Accelerometers overcome many of the inherent limitations of other measurement methods; for example, unlike self-reported instruments, accelerometers are free from random and systematic errors introduced by respondents and interviewers, cultural tradition, and language. However, accelerometers have their own set of limitations; for example, not all accelerometers are created equal and raw accelerometer data require significant data mining procedures in order to yield meaningful outcome variables. Therefore the overall purpose of this three study dissertation was to determine the impact accelerometer model has on the development of a comprehensive physical activity and sedentary behaviour profile and to design and apply novel profiling methods in an order to gain new insights into childrens physical activity.<p> Study One Purpose: To determine which of the three most commonly used accelerometer models has the best intra- and inter-instrument reliability using a mechanical laboratory setup. Secondly, to determine the effect acceleration and frequency have on these reliability measures. Methods: Three experiments were performed. In the first, five each of the Actical, Actigraph, and RT3 accelerometers were placed on a hydraulic shaker plate and simultaneously accelerated in the vertical plane at varying accelerations and frequencies. Six different conditions of varying intensity were used to produce a range of accelerometer counts. Reliability was calculated using standard deviation, standard error of the measurement, coefficient of variation, and intraclass correlation coefficients. In the second and third experiment, 39 Actical and 50 Actigraph accelerometers were put through the same six conditions. Results: Experiment One showed poor reliability in the RT3 (intra- and inter-instrument CV > 40%). Experiments Two and Three clearly indicated that the Actical (CVintra = 0.5%; CVinter = 5.4%) was more reliable than the Actigraph (CVintra = 3.2%; CVinter = 8.6%). Variability in the Actical was negatively related to the acceleration of the condition while no relationship was found between acceleration and reliability in the Actigraph. Variability in the Actigraph was negatively related to the frequency of the condition while no relationship was found between frequency and reliability in the Actical. Conclusion: Of the three accelerometer models measured in this study, the Actical had the best intra- and inter-instrument reliability. However, discrepant trends in the variability of Actical and Actigraph counts across accelerations and frequencies preclude the selection of a superior model. More work is needed to understand why accelerometers designed to measure the same thing, behave so differently.<p> Study Two The accurate measurement of habitual physical activity is fundamental to the study of the relationship between physical activity and health. However, many physical activity measurement techniques produce variables accurate to only the day level, such as total energy expenditure via self-report questionnaire, pedometer step counts or accelerometer measurements of minutes of moderate to vigorous physical activity. Monitoring technologies providing more detailed information on physical activity/sedentary behaviour can now be used to explore the relationships between health and movement frequency, intensity, and duration more comprehensively. This paper explores the activity and sedentary profile that can be acquired through objective monitoring, with a focus on accelerometry. Using previously collected objective data, a detailed physical activity profile is presented and case study examples of data utilization and interpretation are provided. The rich detail captured through comprehensive profiling creates new surveillance and study possibilities and could inform new physical activity guidelines. Data are presented in various formats to demonstrate the dangers of misinterpretation when monitoring population adherence to Canadas Physical Activity Guidelines. Recommendations for physical activity and sedentary profiling are provided and future research needs identified.<p> Study Three Purpose: This study explored the influence of modernity on the physical activity behaviours (e.g. intensity and timing) of children. Methods: Children aged 8-13 years living a traditional lifestyle (Old Order Amish; OOA n=68, Old Order Mennonite; OOM n=120) were compared with children living a contemporary lifestyle (rural Saskatchewan; RSK n=132 and urban Saskatchewan; USK n=93). Physical activity was objectively assessed for seven consecutive days using Actigraph 7164 accelerometers. Custom software was used to reduce the raw accelerometer data into standardized outcome variables. Results: On weekdays there were group differences in moderate physical activity between all lifestyle groups (OOA > OOM > USK > RSK). On the weekend, the group differences in moderate physical activity persisted between, but not within, lifestyle groups (OOA = OOM > USK = RSK). During school hours, all groups had similar activity and sedentary timings; however, they differed in magnitude with the OOA and OOM being both more sedentary and more active. Compared to in school, the OOA and OOM children had 44% lower sedentary time out of school compared to only 15% lower for RSK and USK children. Conclusions: Though cross-sectional, these data suggest that contemporary/modern living is associated with lower levels of moderate and vigorous intensity physical activity compared to lifestyles representative of earlier generations. Analyzing the physical activity and sedentary patterns of traditional lifestyle groups such as the OOA and OOM can provide valuable insight into the quantity and quality of physical activity necessary to promote health.<p> General Conclusions: Together, these three studies will help contribute to the generation of best practices in the accelerometric profiling of both physical activity and sedentary behaviours.

Advances in electronic sensor technologies have led to the increased use of accelerometers for measuring physical activity and sedentary behaviours. Accelerometers overcome many of the inherent limitations of other measurement methods; for example, unlike self-reported instruments, accelerometers are free from random and systematic errors introduced by respondents and interviewers, cultural tradition, and language. However, accelerometers have their own set of limitations; for example, not all accelerometers are created equal and raw accelerometer data require significant data mining procedures in order to yield meaningful outcome variables. Therefore the overall purpose of this three study dissertation was to determine the impact accelerometer model has on the development of a comprehensive physical activity and sedentary behaviour profile and to design and apply novel profiling methods in an order to gain new insights into childrens physical activity.<p> Study One Purpose: To determine which of the three most commonly used accelerometer models has the best intra- and inter-instrument reliability using a mechanical laboratory setup. Secondly, to determine the effect acceleration and frequency have on these reliability measures. Methods: Three experiments were performed. In the first, five each of the Actical, Actigraph, and RT3 accelerometers were placed on a hydraulic shaker plate and simultaneously accelerated in the vertical plane at varying accelerations and frequencies. Six different conditions of varying intensity were used to produce a range of accelerometer counts. Reliability was calculated using standard deviation, standard error of the measurement, coefficient of variation, and intraclass correlation coefficients. In the second and third experiment, 39 Actical and 50 Actigraph accelerometers were put through the same six conditions. Results: Experiment One showed poor reliability in the RT3 (intra- and inter-instrument CV > 40%). Experiments Two and Three clearly indicated that the Actical (CVintra = 0.5%; CVinter = 5.4%) was more reliable than the Actigraph (CVintra = 3.2%; CVinter = 8.6%). Variability in the Actical was negatively related to the acceleration of the condition while no relationship was found between acceleration and reliability in the Actigraph. Variability in the Actigraph was negatively related to the frequency of the condition while no relationship was found between frequency and reliability in the Actical. Conclusion: Of the three accelerometer models measured in this study, the Actical had the best intra- and inter-instrument reliability. However, discrepant trends in the variability of Actical and Actigraph counts across accelerations and frequencies preclude the selection of a superior model. More work is needed to understand why accelerometers designed to measure the same thing, behave so differently.<p> Study Two The accurate measurement of habitual physical activity is fundamental to the study of the relationship between physical activity and health. However, many physical activity measurement techniques produce variables accurate to only the day level, such as total energy expenditure via self-report questionnaire, pedometer step counts or accelerometer measurements of minutes of moderate to vigorous physical activity. Monitoring technologies providing more detailed information on physical activity/sedentary behaviour can now be used to explore the relationships between health and movement frequency, intensity, and duration more comprehensively. This paper explores the activity and sedentary profile that can be acquired through objective monitoring, with a focus on accelerometry. Using previously collected objective data, a detailed physical activity profile is presented and case study examples of data utilization and interpretation are provided. The rich detail captured through comprehensive profiling creates new surveillance and study possibilities and could inform new physical activity guidelines. Data are presented in various formats to demonstrate the dangers of misinterpretation when monitoring population adherence to Canadas Physical Activity Guidelines. Recommendations for physical activity and sedentary profiling are provided and future research needs identified.<p> Study Three Purpose: This study explored the influence of modernity on the physical activity behaviours (e.g. intensity and timing) of children. Methods: Children aged 8-13 years living a traditional lifestyle (Old Order Amish; OOA n=68, Old Order Mennonite; OOM n=120) were compared with children living a contemporary lifestyle (rural Saskatchewan; RSK n=132 and urban Saskatchewan; USK n=93). Physical activity was objectively assessed for seven consecutive days using Actigraph 7164 accelerometers. Custom software was used to reduce the raw accelerometer data into standardized outcome variables. Results: On weekdays there were group differences in moderate physical activity between all lifestyle groups (OOA > OOM > USK > RSK). On the weekend, the group differences in moderate physical activity persisted between, but not within, lifestyle groups (OOA = OOM > USK = RSK). During school hours, all groups had similar activity and sedentary timings; however, they differed in magnitude with the OOA and OOM being both more sedentary and more active. Compared to in school, the OOA and OOM children had 44% lower sedentary time out of school compared to only 15% lower for RSK and USK children. Conclusions: Though cross-sectional, these data suggest that contemporary/modern living is associated with lower levels of moderate and vigorous intensity physical activity compared to lifestyles representative of earlier generations. Analyzing the physical activity and sedentary patterns of traditional lifestyle groups such as the OOA and OOM can provide valuable insight into the quantity and quality of physical activity necessary to promote health.<p> General Conclusions: Together, these three studies will help contribute to the generation of best practices in the accelerometric profiling of both physical activity and sedentary behaviours.

Thesis studied correlations between swallowing accelerometry parameters and anthropometrics in 50 healthy participants. Anthropometrics include: age, gender, weight, height, body fat percent, neck circumference and mandibular length. Dual-axis swallowing signals, from a biaxial accelerometer were obtained for 5-saliva and 10-water (5-wet and 5-wet chin-tuck) swallows per participant. Two patient-independent automatic segmentation algorithms using discrete wavelet transforms of swallowing sequences segmented: 1) saliva/wet swallows and 2) wet chin-tuck swallows. Extraction of swallows hinged on dynamic thresholding based on signal statistics. Canonical correlation analysis was performed on sets of anthropometric and swallowing signal variables including: variance, skewness, kurtosis, autocorrelation decay time, energy, scale and peak-amplitude. For wet swallows, significant linear relationships were found between signal and anthropometric variables. In superior-inferior directions, correlations linked weight, age and gender to skewness and signal-memory. In anterior-posterior directions, age was correlated with kurtosis and signal-memory. No significant relationship was observed for dry and wet chin-tuck swallowing

Thesis studied correlations between swallowing accelerometry parameters and anthropometrics in 50 healthy participants. Anthropometrics include: age, gender, weight, height, body fat percent, neck circumference and mandibular length. Dual-axis swallowing signals, from a biaxial accelerometer were obtained for 5-saliva and 10-water (5-wet and 5-wet chin-tuck) swallows per participant. Two patient-independent automatic segmentation algorithms using discrete wavelet transforms of swallowing sequences segmented: 1) saliva/wet swallows and 2) wet chin-tuck swallows. Extraction of swallows hinged on dynamic thresholding based on signal statistics. Canonical correlation analysis was performed on sets of anthropometric and swallowing signal variables including: variance, skewness, kurtosis, autocorrelation decay time, energy, scale and peak-amplitude. For wet swallows, significant linear relationships were found between signal and anthropometric variables. In superior-inferior directions, correlations linked weight, age and gender to skewness and signal-memory. In anterior-posterior directions, age was correlated with kurtosis and signal-memory. No significant relationship was observed for dry and wet chin-tuck swallowing

Chronic obstructive pulmonary disease (COPD) patients are generally more sedentary and less physically active than healthy adults; putting them at increased risk of hospitalisation and death. For patients with mild-moderate COPD, physical activity appears to be reduced compared with apparently healthy adults but differences in time spent sedentary are less well established. Additionally, there is a need for a greater understanding of the correlates of behaviour in mild-moderate patients with much of the existing literature focusing on more severe or mixed stage patient samples and with many studies lacking objective behavioural monitoring, not adjusting for confounders and a paucity of data on correlates of sedentary time. Despite having mild-moderate airflow obstruction, these patients also report a range of symptom burdens with some individuals reporting severe symptoms. Subsequently, these patients represent a sub-set of individuals who may require lifestyle interventions. Therefore, factors associated with patients reporting more severe symptoms need to be identified to help understand how this phenomenon may manifest and be intervened upon. For patients with more advanced COPD who are admitted to hospital for an acute exacerbation behavioural intervention focussing on less intense movement may be a more suitable approach for reducing the risk of readmissions than more intense physical activity or exercise. To date no studies have specifically targeted reductions in sedentary behaviour in COPD. In addition, wearable self-monitoring technology may facilitate the provision of such interventions, removing important participation barriers such as travel and cost, but this has not been sufficiently examined in COPD. This thesis investigated: (i) objectively measured physical activity and sedentary time and the correlates of these behaviours for mild-moderate COPD patients and apparently healthy adults (Study One); (ii) factors associated with self-reported symptom severity and exacerbation history in mild-moderate COPD patients (Study Two) and (iii) the feasibility and acceptability of a home-based sedentary behaviour intervention using wearable self-monitoring technology for COPD patients following an acute exacerbation (Study Three). Methods: Study One: COPD patients were recruited from general practitioners and apparently healthy adults from community advertisements. Objectively measured moderate-to-vigorous physical activity (MVPA), light activity and sedentary time for 109 mild-moderate COPD patients and 135 apparently healthy adults were obtained by wrist-worn accelerometry. Patients with at least four valid days (≥10 waking hours) out of a possible seven were included in analysis. A range of demographic, social, symptom-based, general health and physical factors were examined in relation to physical activity and sedentary time using correlations and linear regressions controlling for confounders (age, gender, smoking status, employment status and accelerometer waking wear time). Study Two: In 107 patients recruited from general practitioners, symptoms were assessed using the COPD Assessment Test (CAT) and Modified Medical Research Council (mMRC) questionnaires. Twelve-month exacerbation history was self-reported. Exercise capacity was assessed via incremental shuttle walk test (ISWT) and self-reported usual walking speed. Physical activity and sedentary time were obtained from a wrist-worn accelerometer. Study Three: Patients were randomised in-hospital into a usual care (Control), Education or Education + Feedback group with the intervention lasting 14 days following discharge. The intervention groups received information about reducing prolonged sitting. The Education + Feedback group also received real-time feedback on their sitting time, number of stand-ups and step count at home through an inclinometer linked to a smart device app. The inclinometer also provided vibration prompts to encourage movement when the wearer had been sedentary for too long. Feasibility of recruitment (e.g. uptake and retention) and intervention delivery (e.g. fidelity) were assessed. Acceptability of the intervention technology (e.g. wear compliance, app usage and response to vibration prompts) was also examined. Results: Study One: COPD patients were more sedentary (592±90 versus 514±93 minutes per day, p < 0.05) and accrued less MVPA (12±18 versus 33±32 minutes per day, p < 0.05) than apparently healthy adults. For COPD patients, self-reported dyspnea and percentage body fat were independent correlates of sedentary time and light activity with exercise capacity (incremental shuttle walk test) an independent correlate of MVPA. For apparently healthy adults, percentage body fat and exercise capacity were independent correlates of sedentary time and light activity. Percentage body fat was an independent correlate of MVPA. Study Two: ISWT (B=-0.016±0.005, partial R2=0.117, p=0.004) and years living with COPD (B=0.319±0.122, R2=0.071, p=0.011) were independently associated with CAT score. ISWT (B=-0.002±0.001, R2=0.123, p < 0.001) and vector magnitude counts per minute (VMCPM) (B=0.0001±0.0000, R2=0.050, p=0.011) were independently associated with mMRC grade. MVPA was independently associated with previous exacerbations (B=-0.034±0.012, R2=0.081, p=0.005). Patients reporting a CAT score of > 20 or an mMRC score of ≥2 had lower VMCPM, were more sedentary and took part in less light activity than patients reporting a CAT score of 0-10 or mMRC of 0, respectively. Patients reporting ≥2 exacerbations took part in less MVPA than patients reporting zero exacerbations. Study Three: Study uptake was 31.5% providing a final sample of 33 COPD patients. Retention of patients at two-week follow-up was 51.5% (n=17). Reasons for drop-out were mostly related to being unable to cope with their COPD. Patients wore the inclinometer for 11.8±2.3 days (and charged it 8.4±3.9 times) with at least one vibration prompt occurring on 9.0±3.4 days over the 14 day study period. Overall, 325 vibration prompts occurred with patients responding 106 times (32.6%). 40.6% of responses occurred within 5 minutes of the prompt with patients spending 1.4±0.8 minutes standing and 0.4±0.3 minutes walking, taking 21.2±11.0 steps. Discussion: Study One: COPD patients were less active and more sedentary than apparently healthy adults; however, factors predicting behaviour were similar between groups. Correlates differed between sedentary time, light activity and MVPA for both groups. Interventions to boost physical activity levels and reduce sedentary time should be offered to patients with mild-moderate COPD, particularly those reporting more severe breathlessness. Study Two: Worse exercise capacity, low levels of physical activity and more time spent sedentary are some of the factors associated with patients of the same severity of airflow limitation reporting differing symptom severities. These patients may benefit from both lifestyle and exercise interventions. Study Three: Recruitment and retention rates suggest a trial targeting sedentary behaviour in hospitalised COPD patients is feasible. A revised intervention, building on the successful components of the present feasibility study is justified. Conclusion: The findings from this thesis have contributed a greater understanding of physical activity and sedentary behaviour in COPD and can inform the development of tailored physical activity and sedentary behaviour interventions for patients across the grades of COPD severity.