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| 2. |
- Arvidsson, Daniel, 1974, et al.
(författare)
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Re-examination of accelerometer data processing and calibration for the assessment of physical activity intensity.
- 2019
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : John Wiley & Sons. - 0905-7188 .- 1600-0838. ; 29:10, s. 1442-1452
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Tidskriftsartikel (refereegranskat)abstract
- This review reexamines use of accelerometer and oxygen uptake data for assessment of activity intensity. Accelerometers capture mechanical work, while oxygen uptake captures the energy cost of this work. Frequency filtering needs to be considered when processing acceleration data. A too restrictive filter attenuates the acceleration signal for walking and, to a higher degree, for running. This measurement error affects shorter (children) more than taller (adults) individuals due to their higher movement frequency. Less restrictive filtering includes more movement related signals and provide measures that better capture mechanical work, but may include more noise. An optimal filter cut-point is determined where most relevant acceleration signals are included. Further, accelerometer placement affects what part of mechanical work being captured. While the waist placement captures total mechanical work and therefore contributes to measures of activity intensity equivalent by age and stature, the thigh and wrist placements capture more internal work and do not provide equivalent measures. Value calibration of accelerometer measures is usually performed using measured oxygen uptake with the metabolic equivalent of task (MET) as reference measure of activity intensity. However, the use of MET is not stringent and is not a measure of activity intensity equivalent by age and stature. A candidate measure is the mass-specific net oxygen uptake, VO2 net (VO2 tot - VO2 stand). To improve measurement of physical activity intensity using accelerometers, research developments are suggested concerning processing of accelerometer data, use of energy expenditure as reference for activity intensity, and calibration procedure with absolute versus relative intensity. This article is protected by copyright. All rights reserved.
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- Dencker, Magnus, et al.
(författare)
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BMI and objectively measured body fat and body fat distribution in prepubertal children.
- 2007
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 27:1, s. 12-16
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Tidskriftsartikel (refereegranskat)abstract
- Background Body Mass Index (BMI) is often used as a surrogate estimate of body fat in epidemiological studies. This study explores the association between BMI, body fat and body fat distribution assessed by Dual-Energy X-Ray Absorptiometry (DXA) in younger children. Methods Cross-sectional study of 246 children (138 boys and 108 girls) aged 8-11 years. DXA was used to quantify abdominal fat mass (AFM), total body fat (TBF) and also total body fat as percentage of total body mass (BF%). Body fat distribution was calculated as AFM/TBF. Results We found close correlations between BMI vs. TBF, BF% and AFM (r = 0.94, r = 0.92 and r = 0.93) for boys and (r = 0.95, r = 0.92 and r = 0.95) for girls, respectively (P < 0.05 for all r-values). However, significantly lower correlation (P < 0.001 for difference between the r-values) existed for body fat distribution (r = 0.64 for boys and 0.73 for girls). Conclusion Percentage body fat, TBF and AFM were all closely associated with BMI, suggesting that BMI serves as a good surrogate marker for obesity in population studies. However, a significantly lower correlation existed for BMI vs. body fat distribution, which may be a limitation when BMI is used to study cardiovascular risk factors in epidemiological studies.
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| 4. |
- Dencker, Magnus, et al.
(författare)
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Body fat related to daily physical activity and insulin concentrations in non-diabetic children.
- 2008
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 28, s. 211-215
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Tidskriftsartikel (refereegranskat)abstract
- This study explored the associations between body fat versus daily physical activity and insulin concentrations in non-diabetic young children in a cross-sectional study of 172 children (93 boys and 79 girls) aged 8-11 years. Blood samples were analysed for serum insulin and daily physical activity was measured by accelerometers. Time spent performing vigorous activity was estimated from accelerometer data by using established cut-off points. Dual-energy x-ray absorptiometry (DXA) was used to quantify abdominal fat mass (AFM) and total body fat (TBF), also calculated as percentage of body weight (BF%). Body fat distribution was calculated as AFM/TBF. Body fat distribution was independently linked to both insulin concentrations and physical activity. In contrast, TBF, AFM, and BF% were linked to physical activity only and not to insulin concentrations. In conclusion in this population of non-diabetic children, body fat distribution was independently associated with increased concentrations of insulin and deceased amount of vigorous activity per day. Also, AFM, TBF, and BF% were independently related to minutes of vigorous activity per day.
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| 6. |
- Dencker, Magnus, et al.
(författare)
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Daily physical activity and its relation to aerobic fitness in children aged 8-11 years.
- 2006
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 96:5, s. 587-592
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Tidskriftsartikel (refereegranskat)abstract
- A positive relationship between daily physical activity and aerobic fitness exists in adults. Studies in children have given conflicting results, possibly because of differences in methods used to assess daily physical activity and fitness. No study regarding daily physical activity and fitness in children has been published, where fitness has been assessed by direct measurement of maximum oxygen uptake and related to daily physical activity intensities by accelerometers. We examined 248 children (140 boys and 108 girls), aged 7.9-11.1 years. Maximum workload and maximal oxygen uptake (VO2PEAK) by indirect calorimetry were measured during a maximum bicycle ergometer exercise test. Exercise capacity was adjusted for body mass and (body mass)(2/3). Daily physical activity was evaluated by accelerometers, worn around the waist for 4 days. Mean accelerometer counts and time spent in vigorous physical activity were calculated. VO2PEAK was correlated with mean accelerometer counts (r=0.23 for boys and r=0.23 for girls, both P < 0.05), but somewhat better with time spent in vigorous activity (r=0.32 for boys, r=0.30 for girls, both P < 0.05). All results remained virtually the same regardless of the method used to adjust for differences in body size.
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| 7. |
- Dencker, Magnus, et al.
(författare)
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Gender differences and determinants of aerobic fitness in children aged 8-11 years.
- 2007
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6327 .- 1439-6319. ; 99, s. 19-26
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies of gender differences in maximum oxygen uptake have come to different conclusions. Limited data exists where the determinants of maximum oxygen uptake have been evaluated in a comprehensive manner. Thus, we examined 248 children (140 boys and 108 girls), aged 7.9-11.1 years. Body composition was determined by dual-energy X-ray absorptiometry, measured variables were total body fat (TBF) and lean body mass (LBM). Maximal oxygen uptake (VO2peak) was measured by indirect calorimetry during a maximal cycle exercise test. Daily physical activity was assessed by accelerometers and duration of vigorous activity per day (VPA) was calculated. Left ventricular inner diastolic diameter (LVDD) was measured by echocardiography. Lung function was evaluated with spirometric testing and whole body plethysmography. Boys had between 8 and 18% higher values than girls for VO2peak, dependent upon whether VO2peak was expressed in absolute values or scaled to body mass, LBM or if allometric scaling was used. In multiple regression analysis absolute values of aerobic fitness were independently related to LBM, maximal heart rate (Max HR), gender, LVDD, and VPA. Furthermore, when VO2peak was scaled to body mass it was independently related to In TBF, Max HR, gender, VPA, and LVDD. Lung function had no relation to VO2peak. Our study concludes that body composition is the main predictor for VO2peak, in children aged 8-11 years, whereas VPA or LVDD has only a modest impact. Existing gender differences in VO2peak cannot be explained only by differences in body composition, physical activity, or heart size.
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| 8. |
- Dencker, Magnus, et al.
(författare)
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Health-related aspects of objectively measured daily physical activity in children.
- 2008
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Ingår i: Clinical Physiology and Functional Imaging. - 1475-0961. ; 28, s. 133-144
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Tidskriftsartikel (refereegranskat)abstract
- It is well established that physical inactivity in adults is associated with increased mortality and morbidity. Whether daily physical activity level is related to risk factors for cardiovascular disease (CVD) in children has been debated. Furthermore, objective data on the habitual daily physical activity in children have at large been scarce in the literature. The main reason for this is the fact that daily physical activity is very difficult to measure in children. In recent years, a new device, the accelerometer, has emerged as a frequently used instrument for the measurement of daily physical activity. This review summarizes recently published studies that have used accelerometers to measure daily physical activity in children and related activity data to known risk factors for CVD.
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| 9. |
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| 10. |
- Dieden, Anna, et al.
(författare)
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Effect of food intake on left and right ventricular systolic tissue Doppler measurements.
- 2015
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961. ; 36:5, s. 396-400
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Tidskriftsartikel (refereegranskat)abstract
- Systolic tissue Doppler measurements (s') have been used to measure the velocity in myocardial motion and are a valuable tool for evaluating the systolic function of the left and right ventricles. Digestion of food is known to significantly alter hemodynamics and may therefore affect s'. The effect of food intake on s' parameters has not yet been studied. We assessed whether s' is affected by food intake. Nineteen healthy subjects aged 26·2 ± 4·2 years were investigated. s' was measured with pulsed tissue Doppler imaging in the right and left ventricles before the subjects ate a standardized meal and also 30 and 110 min after the meal. Three measurements were taken in each projection, and a mean value was calculated for each. s' increased significantly (P<0·05) from fasting to 30 min after food intake in every measured site except in the left inferolateral wall (P = 0·15, NS). Several, but not all, variables returned to base value 110 min after food intake. This study shows that food intake affects the tissue Doppler variables used to evaluate systolic heart function. Further studies are needed in older healthy subjects and older subjects with various cardiovascular diseases.
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