Background Obesity is associated with an increased risk of back pain, attributed to elevated mechanical load. Back injury risk is also determined by movement patterns (kinematics) and physiological factors (exertion, muscle activation). Lifting, particularly repetitive, is the most frequently cited injurious activity. However, in spite of the obvious relation, a paucity of information exists quantifying the interaction of obesity and repetition during lifting. Purpose To determine the effects of obesity and repetition on mechanical, kinematic and physiological lifting outcomes. Methods: An individual-specific, biomechanical model (based upon 3D photogrammetry) was developed to estimate the effect of obesity on back load during lifting (study 1). Lifting strategy and physiological outcomes related to obesity were examined in a fixed-pace, repetitive lifting task (study 2). The effect of task constraints on lifting strategy of high and normal BMI individuals were determined (study 3), followed by an evaluation of muscle activation responses during a repetitive trunk motion similar to that encountered during lifting (study 4). Results: Obesity-specific alterations of important determinants of back load (inertia, CMloc) were revealed. Obesity was related to a substantial increase in back load (M=+197.3, SE=16.8 Nm about L5/S1), however the effect differed across lifting tasks. The lifting strategy of high-BMI individuals was characterized by an increased distance to the external mass (M=+4.7, SE=1.8 cm) and shorter lift duration (M=230, SE=130 msec), with increased cardiovascular effort (M=+7.4, SE=3.4% HRmax) but no change in perceived exertion. Lifting frequency was not a major determinant of lifting strategy, however strategy was influenced by the presence and type of external pacing. A phase-specific, rapid alteration in muscle activation response was evident in the MMG signal during the initial repetitions of a repetitive trunk motion. Conclusion: The effect of obesity during lifting is task-dependent, and cannot be attributable solely to mechanical factors. Future studies should consider tasks that are unconstrained, and examine the initial familiarization period of repetitive tasks, specifically the lowering phase of motions. These findings have relevance to back injury mechanisms related to obesity and the design of injury prevention programs for individuals with a high BMI.

Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2008.

The purpose of this study was to examine the effects of body mass and sex on the joint biomechanics of the lower extremity during stair ascent and descent. Nineteen normal weight (8M and11F; BMI: 22.1 ± 1.8 kg/m2), 18 overweight (14M and 4F; BMI: 27.4 ± 1.3 kg/m2) and 8 obese subjects (3M and 5F; BMI: 33.3 ± 2.5 kg/m2) were recruited. Joint mechanical loading presented by joint moment of force and peak joint angles at the hip, knee, and ankle during stair climbing were recorded and analyzed using a motion analysis system with 10 cameras and 4 force plates. The MANOVA and linear regression analysis found a significantly larger knee extensor moment (p=0.026) among the overweight compared to the normal weight participants during descent. Sex differences were found in the peak joint angles, as the females abducted their knees more than the males (p=0.002; r(51) = 0.51) during descent.

Obesity and being overweight have become growing concerns due to their association with many diseases, such as type II diabetes, several types of cancer and heart disease. Thus, obesity treatments have been the focus of a large number of recent studies. Because of these studies, researchers have found that the treatment of obesity and being overweight requires constant monitoring of the patient’s diet. Therefore, measuring food intake each day is considered an important step in the success of a healthy diet. Measuring daily food consumption for obese patients is one of the challenges in obesity management studies. Countless recent studies have suggested that using technology like smartphones may enhance the under-reporting issue in dietary intake consumption. In this thesis, we propose a Food Recognition System (FRS) for calories and nutrient values assumption. The user employs the built-in camera of the smartphone to take a picture of any food before and after eating. The system then processes and classifies the images to detect the type of food and portion size, then uses the information to estimate the number of calories in the food. The estimation and calculation of the food volume and amount of calories in the image is an essential step in our system. Via special approaches, the FRS can estimate the food volume and the existing calories with a high level of accuracy. Our experiment shows high reliability and accuracy of this approach, with less than 15% error.

Ninety-four children (age 8-17 yrs; BMI ≥ 95th percentile) were staged according to their risk profile in manuscript one by the Edmonton Obesity Staging System for Pediatrics (EOSS-P) based on metabolic, mechanical, mental and/or family risk factors. Children completed a maximal treadmill test yielding VO2peak data (mlO2/kg/min). Children were stratified into three groups: (Stage 1 n=28; Stage 2 n=47; Stage 3 n=19). VO2peak was significantly lower in Stage 3 (p = 0.02) compared to Stages 1 and 2. Children were re-stratified into three groups for manuscript two without the family category of the EOSS-P applied: Low Risk (LR) (n=40); Elevated Risk (ER) (n=45); and High Risk (HR) (n=9). VO2peak was significantly lower in the HR group (p = 0.04) compared to the LR group. Stage 3/HR children (highest risk category) in both manuscripts displayed the lowest levels of cardiorespiratory fitness, suggesting an increased risk for complications associated with pediatric obesity.

Thesis (M.Sc. (Human Movement Science))--North-West University, Potchefstroom Campus, 2008.

Background: Prevalence of diabetes and cardiovascular disease among First Nations populations in Canada is higher compared to the non-First Nations population. Consistent monitoring of this epidemic is required. In addition, cardiovascular risk factors derived from research on non-First Nations populations may not be applicable to First Nations populations. Therefore, better understandings of risk factors specific to First Nations populations are required. Purpose: To characterize cardiovascular risk in a Manitoba First Nation population. Methods: Data from the 2002/2003 and 2011/2012 Diabetes Screening Studies in Sandy Bay First Nation were used, including fasting blood, anthropometric, and self-report data. The studies were conducted using a community-based participatory framework. All non-pregnant community members aged ≥18 years old were invited to participate in both study periods. First, using a repeated cross-sectional design, the burden of cardiovascular risk in the community in the 2011/2012 sample (n=482) was compared to the 2002/2003 sample (n=596). Second, by linking 2002/2003 and 2011/2012 data, an eight-year follow-up of participants was developed (n=171). Results: Repeated cross-sectional design. Sex- and age-standardized prevalence of diabetes in the adult population of the community was estimated at 39.2% (95% CI: 35.3, 43.1) in 2011/2012 and was not significantly different from 2002/2003. Significantly higher crude prevalence of obesity, abdominal obesity, dyslipidemia, and metabolic syndrome among women compared to men persisted from 2002/2003 to 2011/2012. At 80.0%, the crude prevalence of current smoking was significantly higher in 2011/2012 compared to 2002/2003. Prospective cohort design. There were 35 (95% CI: 26, 45) new cases of diabetes among 128 participants without diabetes at baseline (27% over 8 years or 3.3% per year). Two-thirds of those with diabetes at follow-up lost weight, including 35.1% of men, and 18.9% of women that lost greater than 10kg. Both men and women lost weight in association with decreases in fasting blood insulin, while men also lost weight in association with uncontrolled blood glucose. Conclusions: This research contributes to the understanding of the diabetes epidemic and how this epidemic has evolved in a high-risk community. Unintentional weight loss related to diabetes is a problem in this population. Further research is needed to better understand how diabetes-related weight loss may contribute to morbidity and mortality.

No description available.

Fetal overgrowth is associated with adverse outcomes for offspring and with maternal obesity. Results from a systematic review and meta-analysis showed that maternal obesity is associated with fetal overgrowth, defined as birthweight ≥4000g (OR 2.17, 95% CI 1.92, 2.45), birthweight ≥4500g (OR 2.77, 95% CI 2.22, 3.45) and birthweight ≥90%ile for gestational age (OR 2.42, 95% CI 2.16, 2.72). A retrospective cohort study revealed that mothers whose infants are macrosomic are more likely to require induction of labour (OR 1.42, 95% CI 1.10-1.98) and delivery by Cesarean section (OR 1.45, 95% CI 1.04-2.01), particularly for maternal indications (OR 3.7, 95% CI 1.47-9.34), if they are obese. Infants from these pregnancies are significantly more likely to require neonatal resuscitation in the form of free flow oxygen (OR 1.57, 95% CI 1.03, 2.42) than macrosomic infants of non-obese mothers. Thus, co-existing maternal obesity and macrosomia increases the risk of adverse pregnancy outcomes.

Obesity is an accumulation of adipose tissue to the point of negative health outcomes; the association of obesity with type 2 diabetes and cardiovascular disease is particularly profound. Notably, obesity has begun to be associated with impairments in cognitive function; however, the underlying cellular mechanisms are poorly understood. Behavioural studies have demonstrated a link between a high fat diet and impaired hippocampal function, and our aim was to characterize protein level changes in the hippocampus of an obese female rat model. Female rats were fed either a control diet (CD; 10% kcal from fat), or a high-fat diet (HFD; 45% kcal from fat) for 16 weeks. Body weight, food consumption, fasting blood glucose levels, and glucose tolerance were monitored. Upon sacrifice brain, liver, adrenal glands, spleens and fat pads were harvested and analyzed. Plasma leptin and insulin levels were also measured. The distribution of NMDA receptor subunits was examined by using either cell-surface biotinylation, or differential filtration-centrifugation followed by immunoblotting. The feeding protocol induced an obese phenotype in female rats characterized by larger fat pads, spleens and adrenal glands, as well as greater problems handling a glucose load. However, cellular, surface and synaptic expression of NMDA receptor subunits (GluN1, GluN2A & GluN2B) were not significantly altered, which suggests that changes downstream of the receptor may be responsible for the effects of HFD on cognitive behaviour.