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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Obesity occurs when energy intake exceeds energy expenditure. Humans expend energy through purposeful exercise and through changes in posture and movement that are associated with the routines of daily life [called nonexercise activity thermogenesis (NEAT)]. To examine NEAT's role in obesity, we recruited 10 lean and 10 mildly obese sedentary volunteers and measured their body postures and movements every half-second for 10 days. Obese individuals were seated, on average, 2 hours longer per day than lean individuals. Posture allocation did not change when the obese individuals lost weight or when lean individuals gained weight, suggesting that it is biologically determined. If obese individuals adopted the NEAT-enhanced behaviors of their lean counterparts, they might expend an additional 350 calories (kcal) per day.
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PMID:Interindividual variation in posture allocation: possible role in human obesity. 1568 73

The functional or sphere-fitting method has been proposed as an alternative to the traditional predictive approach to locating hip centers based on inter-ASIS breadth. In the functional approach, the movement of a marker on the thigh is fit to a sphere whose center coincides with the hip joint center. The first objective of this study was to determine the required parameters that allow an accurate application of a sphere-fitting method. The parameters examined in this study included: (1) the range of motion in flexion-extension and abduction-adduction, (2) the specific algorithm used to fit a sphere to the data, (3) the method of placing markers on the thigh, and (4) the type of motion used to generate points, either walking or a standing leg motion (SLM) trial. This objective was addressed with a computer simulation and clinical data. The second objective was to compare the accuracy of the functional method to the traditional predictive approach in a group of nine human subjects. The location of the hip center estimates from both methods were compared to an ultrasound-determined hip center standard, and linear errors and errors along each axis were compared. Results from the computer simulation indicated that an iterative algorithm is needed, with a method using the derivative yielding slightly more accurate results. Clinical results indicated that the functional method with a standing leg motion trial produced significantly smaller errors in hip joint center estimates (1.34 cm) versus the predictive method (2.16 cm). In addition, the range of error across hips was smaller for the functional method. If high joint center accuracy is needed or in populations characterized by obesity or pelvic asymmetries, the subject specificity and independence from anatomical landmarks characteristic of the functional method would likely provide more accurate results.
Gait Posture 2005 Oct
PMID:Clinical applicability of using spherical fitting to find hip joint centers. 1613 49

There may be concerns about the validity of kinetic models when studying locomotion in obese subjects (OS). The aim of the present study was to improve and validate a relevant representation of obese subject from four kinetic models. Fourteen teenagers with severe primary obesity (BMI = 40 +/- 5.2 kg/m(2)), were studied during jumping. The jumps were filmed by six cameras (synchronized, 50 Hz), associated with a force-plate (1,000 Hz). All the tested models were valid; the linear mechanical analysis of the jumps gave similar results (p > 0.05); but there were significantly different segment inertias when considering the subjects' abdomen (p < 0.01), which was associated with a significantly higher mechanical internal energy expenditure (p < 0.01) than that estimated from Dempster's and Hanavan's model, by about 40 and 30%. The validation of a modelling specifically for obese subjects will enable a better understanding of their locomotion.
Gait Posture 2006 Feb
PMID:Validation and influence of anthropometric and kinematic models of obese teenagers in vertical jump performance and mechanical internal energy expenditure. 1639 10

Proper balance control is a key aspect of acitivities of daily living. The aim of this study was to determine the contribution of body weight to predict balance stability. The balance stability of 59 male subjects with BMI ranging from 17.4 to 63.8kg/m(2) was assessed using a force platform. The subjects were tested with and without vision. A stepwise multiple regression analysis was used to determine the independent effect of body weight, age, body height and foot length on balance stability (i.e., mean speed of the center of foot pressure). With vision, the stepwise multiple regression revealed that body weight accounted for 52% of the variance of balance stability. The addition of age contributed a further 3% to explain balance control. Without vision, body weight accounted for 54% of the variance and the addition of age and body height added a further 8% and 1% to explain the total variance, respectively. The final model explained 63% of the variance. A decrease in balance stability is strongly correlated to an increase in body weight. This suggests that body weight may be an important risk factor for falling. Future studies should examine more closely the combined effect of aging and obesity on falling and injuries and the impact of obesity on the diverse range of activities of daily living.
Gait Posture 2007 Jun
PMID:Body weight is a strong predictor of postural stability. 1693 Oct 18

The biomechanical changes in postural control and in motor activities linked to obesity are still not fully understood. The aim of this study was to assess the adaptation in static and dynamic control of equilibrium when the body mass to be stabilized and moved is increased through obesity. Postural stability limits and gait initiation at slow and fast velocities were compared in a case control study that included a group of obese adolescents and a control group of adolescents with normal weight. The consequences of overweight are more clearly evident from the results on dynamic stability of the obese group than those on static equilibrium. Both the lower values of the biomechanical parameters characterizing the progression velocity of gait and the longer duration of the swing phase for the fast velocity condition suggest that obesity acts as a slowing factor. However, the reduction of the postural stability limits of the obese group, their inability to increase the anticipatory phase duration unlike the control group, the increase in the double support phase duration as well as some difficulty in controlling the fall of the centre of gravity suggest that, in these subjects, an adaptive strategy is adopted to preserve equilibrium by limiting progression velocity.
Gait Posture 2008 Jul
PMID:Postural control in obese adolescents assessed by limits of stability and gait initiation. 1819 68

Our goal was to examine the gait patterns of older adults with Down syndrome (DS) for precocious stabilizing adaptations during comfortable over-ground walking and in more challenging conditions. Twelve participants with DS and 12 with typical development (TD) were matched for height, weight and age (range 35-62 years). We used a six-camera motion capture system to assess foot trajectories over obstacles. Participants first walked at their preferred speed over a 5.3 m instrumented gait mat (unperturbed condition). Subsequent walking trials included perturbations mid-walkway: (a) minimal obstacle to step over (12 cm high), (b) moderate obstacle to step onto with both feet and then off (standard step), and (c) maximum obstacle to step onto with only one foot and over with the other (standard step). Adults with DS walked slower with shorter, wider strides while spending more time in both stance and double support. These adaptations increased during the moderate and maximal perturbations. They stepped with the minimal perturbation obstacle further forward in their crossing step and produced a lower, flatter trajectory of the lead foot, with less dorsiflexion at crossing. This strategy decreased trailing toe clearance but did not alter leading heel clearance. The combined effects of ligamentous laxity, low tone, obesity, inactivity and physiological decrements associated with aging lead to these stability-enhancing adaptations at a younger chronological age in adults with DS. We believe intervention to increase overall stability will be beneficial in helping adults with DS maintain optimal functional mobility and health.
Gait Posture 2008 Oct
PMID:Early onset of stabilizing strategies for gait and obstacles: older adults with Down syndrome. 1835 29

Postural stresses related to manual work tasks may be significantly affected by the bodily condition of workers. One such condition is obesity, which is characterised by excess fat mass in the body. This study empirically examined the obesity effect on postural stress during static posture maintenance tasks. In total, 20 obese and 20 non-obese participants performed static box-holding for a set of 84 working postures defined based on the Ovako Working Posture Analysing System. The participants reported postural stresses using the rated perceived exertion scale. Obesity was found to significantly increase postural stress across the 84 working postures and, also, amplify the effects of postural changes on postural stress. The study findings suggest that ergonomic workplace/job design for obese workers would be a challenge requiring a proactive approach and creativity in problem solving. In addition, the use of ergonomic knowledge in design would be more critical when targeting obese than non-obese workers. The study findings are relevant to ergonomic workplace/job design for obese workers.
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PMID:Obesity effect on perceived postural stress during static posture maintenance tasks. 1960 68

Obese children move less and with greater difficulty than normal-weight counterparts but expend comparable energy. Increased metabolic costs have been attributed to poor biomechanics but few studies have investigated the influence of obesity on mechanical demands of gait. This study sought to assess three-dimensional lower extremity joint powers in two walking cadences in 28 obese and normal-weight children. 3D-motion analysis was conducted for five trials of barefoot walking at self-selected and 30% greater than self-selected cadences. Mechanical power was calculated at the hip, knee, and ankle in sagittal, frontal and transverse planes. Significant group differences were seen for all power phases in the sagittal plane, hip and knee power at weight acceptance and hip power at propulsion in the frontal plane, and knee power during mid-stance in the transverse plane. After adjusting for body weight, group differences existed in hip and knee power phases at weight acceptance in sagittal and frontal planes, respectively. Differences in cadence existed for all hip joint powers in the sagittal plane and frontal plane hip power at propulsion. Frontal plane knee power at weight acceptance and sagittal plane knee power at propulsion were significantly different between cadences. Larger joint powers in obese children contribute to difficulty performing locomotor tasks, potentially decreasing motivation to exercise.
Gait Posture 2010 Jun
PMID:Body size and walking cadence affect lower extremity joint power in children's gait. 2057 Jan 52

The incidence of obesity has increased dramatically in children and adolescents, and with this comes health risks typically associated with adult obesity. Among those health consequences are musculoskeletal damage and pain. Previous studies have demonstrated inconsistent effects of increased body mass on movement patterns in adults and children who are obese. The purpose of this study was to investigate frontal and sagittal plane mechanics during walking in adolescents who were obese. Adolescents (12-17 years) who were obese were recruited from a weight management program, and healthy weight peers (matched for age, race and gender) were recruited from the community. Three-dimensional motion analysis of the lower extremities was performed during walking. Analysis of kinematic and kinetic data from 36 adolescents who were obese and healthy weight revealed significant differences in mechanics at all lower extremity joints in both sagittal and frontal planes. Subjects who were obese seemed to use movement strategies that minimized joint moments, especially at the hip and knee during walking. The lower extremity mechanics during walking in the subjects who were obese raise concerns about maintenance of structural integrity of the lower extremity joints over time, given the repeated high stresses across the joints even with walking. Neither the long term consequences of these atypical movement patterns, nor the ability to alter these patterns through therapeutic activities or weight loss has been investigated in adolescents who are obese.
Gait Posture 2010 Jun
PMID:Sagittal and frontal plane joint mechanics throughout the stance phase of walking in adolescents who are obese. 2057 11

There is preliminary evidence that BMI is positively correlated with movement variability of standing posture. However, this negative effect of obesity on postural control may be mediated by the change in other body scale variables (e.g., mechanical and fitness) that also occur with changes in BMI. This study investigated the influence of selected body scale (height, body mass, BMI), body composition (body fat percentage), mechanical (moment of inertia - MI) and strength (S) variables as predictors of the control of postural motion in adolescents. 125 healthy adolescents (65 boys, 60 girls) with a wide range of BMI (13.8-31.0 kg/m(2)) performed a battery of tests that assessed body composition, anthropometry, muscular strength and postural control. Multiple measures of postural motion variability were derived for analysis with body scale, mechanical and lower extremity strength variables separately for boys and girls. BMI, height and body mass, considered both separately and collectively, were poor and/or inconsistent predictors of variability in all three posture tasks. However, the ratio of lower extremity strength to whole body moment of inertia showed the highest positive correlation to most postural variability measures in both boys and girls and these effects were strongest in the less stable tasks of single leg standing and recovery of stance. Our findings support the hypothesis that diminished lower extremity strength to mechanical constraint ratio compromises the robustness of the strength to body scale relation in movement and postural control.
Gait Posture 2012 Feb
PMID:Obesity, mechanical and strength relationships to postural control in adolescence. 2201 1


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