| 1. |
|
|
| 2. |
- Brage, Søren, et al.
(författare)
-
Hierarchy of individual calibration levels for heart rate and accelerometry to measure physical activity.
- 2007
-
Ingår i: J Appl Physiol. - : American Physiological Society. - 8750-7587. ; 103:2, s. 682-92
-
Tidskriftsartikel (refereegranskat)abstract
- Combining accelerometry with heart rate (HR) monitoring may improve precision of physical activity measurement. Considerable variation exists in the relationships between physical activity intensity (PAI) and HR and accelerometry, which may be reduced by individual calibration. However, individual calibration limits feasibility of these techniques in population studies, and less burdensome, yet valid, methods of calibration are required. We aimed to evaluate the precision of different individual calibration procedures against a reference calibration procedure: a ramped treadmill walking-running test with continuous measurement of PAI by indirect calorimetry in 26 women and 25 men [mean (SD): 35 ( 9 ) yr, 1.69 (0.10) m, 70 ( 14 ) kg]. Acceleration (along the longitudinal axis of the trunk) and HR were measured simultaneously. Alternative calibration procedures included treadmill testing without calorimetry, submaximal step and walk tests with and without calorimetry, and nonexercise calibration using sleeping HR and gender. Reference accelerometry and HR models explained >95% of the between-individual variance in PAI ( P < 0.001). This fraction dropped to 73 and 81%, respectively, for accelerometry and HR models calibrated with treadmill tests without calorimetry. Step-test calibration captured 62–64% (accelerometry) and 68% (HR) of the variance between individuals. Corresponding values were 63–76% and 59–61% for walk-test calibration. There was only little benefit of including calorimetry during step and walk calibration for HR models. Nonexercise calibration procedures explained 54% (accelerometry) and 30% (HR) of the between-individual variance. In conclusion, a substantial proportion of the between-individual variance in relationships between PAI, accelerometry, and HR is captured with simple calibration procedures, feasible for use in epidemiological studies.
|
|
| 3. |
- Ekelund, Ulf, et al.
(författare)
-
Independent associations of physical activity and cardiorespiratory fitness with metabolic risk factors in children : the European youth heart study
- 2007
-
Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 50:9, s. 1832-1840
-
Tidskriftsartikel (refereegranskat)abstract
- AIMS/HYPOTHESIS: High levels of cardiorespiratory fitness (CRF) and physical activity (PA) are associated with a favourable metabolic risk profile. However, there has been no thorough exploration of the independent contributions of cardiorespiratory fitness and subcomponents of activity (total PA, time spent sedentary, and time spent in light, moderate and vigorous intensity PA) to metabolic risk factors in children and the relative importance of these factors. METHODS: We performed a population-based, cross-sectional study in 9- to 10- and 15- to 16-year-old boys and girls from three regions of Europe (n = 1709). We examined the independent associations of subcomponents of PA and CRF with metabolic risk factors (waist circumference, BP, fasting glucose, insulin, triacylglycerol and HDL-cholesterol levels). Clustered metabolic risk was expressed as a continuously distributed score calculated as the average of the standardised values of the six subcomponents. RESULTS: CRF (standardised beta = -0.09, 95% CI -0.12, -0.06), total PA (standardised beta = -0.08, 95% CI -0.10, -0.05) and all other subcomponents of PA were significantly associated with clustered metabolic risk. After excluding waist circumference from the summary score and further adjustment for waist circumference as a confounding factor, the magnitude of the association between CRF and clustered metabolic risk was attenuated (standardised beta = -0.05, 95% CI -0.08, -0.02), whereas the association with total PA was unchanged (standardised beta = -0.08 95% CI -0.10, -0.05). CONCLUSIONS/INTERPRETATION: PA and CRF are separately and independently associated with individual and clustered metabolic risk factors in children. The association between CRF and clustered risk is partly mediated or confounded by adiposity, whereas the association between activity and clustered risk is independent of adiposity. Our results suggest that fitness and activity affect metabolic risk through different pathways.
|
|
| 4. |
- Ekelund, Ulf, et al.
(författare)
-
Prevalence and correlates of the metabolic syndrome in a population-based sample of European Youth
- 2009
-
Ingår i: American Journal of Clinical Nutrition. - Bethseda, Md. : American Society for Nutrition. - 0002-9165 .- 1938-3207. ; 89:1, s. 90-96
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Until recently, there has been no unified definition of the metabolic syndrome (MetS) in the youth. Therefore, the prevalence of MetS and its association with potential correlates are largely unknown. OBJECTIVE: The objective was to quantify the prevalence, identify the correlates, and examine the independent associations between potential correlates with MetS. DESIGN: A population-based cohort study was conducted in 10- and 15-y-old youth from Estonia, Denmark, and Portugal (n = 3193). MetS was defined according to the International Diabetes Federation. Correlates included maternal socioeconomic status, body mass index (BMI), hypertension, and prevalent diabetes and maternally reported child's birth weight and duration of breastfeeding. Data on sexual maturity, objectively measured physical activity, cardiorespiratory fitness, self-reported sports participation, television viewing, and regular play were collected for the children. RESULTS: The prevalence of MetS was 0.2% and 1.4% in 10- and 15-y-olds, respectively. Cardiorespiratory fitness (standardized odds ratio: 0.33; 95% CI: 0.15, 0.75), physical activity (standardized odds ratio: 0.40; 95% CI: 0.18, 0.88), and maternal BMI (standardized odds ratio: 1.61; 95% CI: 1.11, 2.34) were all independently associated with MetS after adjustment for sex, age group, study location, birth weight, and sexual maturity. An increase in daily moderate-intensity physical activity by 10-20% was associated with a 33% lower risk of being categorized with MetS. CONCLUSIONS: High maternal BMI and low levels of cardiorespiratory fitness and physical activity independently contribute to the MetS and may be targets for future interventions. Relatively small increases in physical activity may significantly reduce the risk of MetS in healthy children.
|
|
| 5. |
- Nilsson, Andreas, 1973-, et al.
(författare)
-
Between- and within-day variability in physical activity and inactivity in 9- and 15-year-old European children
- 2009
-
Ingår i: Scandinavian Journal of Medicine and Science in Sports. - Oxford : Wiley-Blackwell. - 0905-7188 .- 1600-0838. ; 19:1, s. 10-18
-
Tidskriftsartikel (refereegranskat)abstract
- To examine differences in levels of physical activity (PA), time spent at moderate-to-vigorous intensity PA (MVPA) and time spent sedentary between and within days in children from four European countries, 1954 9 - and 15-year-olds were included. PA was measured during 2 weekdays and 2 weekend days using the manufacturing technology-incorporated (MTI) accelerometer. Average count per minute, time spent sedentary, time spent at MVPA and the proportion of children accumulating > or =60 min of MVPA were calculated. Data were compared between weekdays and weekend days and between school time and leisure-time. Although not entirely consistent across countries, overall PA, time spent sedentary and the proportion of children accumulating > or =60 min of MVPA were higher during weekdays compared with weekend days. Differences in overall PA between school time and leisure-time were highly inconsistent between countries. Few children (4-31%) accumulated > or =60 min of MVPA either during school time or during leisure-time. Differences in activity patterns between weekdays and weekend days are explained by less accumulated time in MVPA during weekend days. Weekend days and leisure-time during weekdays seem appropriate targets when promoting PA in order to increase the proportion of children achieving current recommendations on health-enhancing PA.
|
|
| 6. |
- Nilsson, Andreas, 1973-, et al.
(författare)
-
Correlates of objectively assessed physical activity and sedentary time in children : a cross-sectional study (The European Youth Heart Study)
- 2009
-
Ingår i: BMC Public Health. - London : BioMed Central. - 1471-2458. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundIdentifying leisure time activities performed before and after school that influence time in physical activity (PA) and/or time spent sedentary can provide useful information when designing interventions aimed to promote an active lifestyle in young people. The purpose of this study was to examine associations between mode of transportation to school, outdoor play after school, participation in exercise in clubs, and TV viewing with objectively assessed PA and sedentary behaviour in children.MethodsA total of 1327 nine- and 15-year-old children from three European countries (Norway, Estonia, Portugal) participated as part of the European Youth Heart Study. PA was measured during two weekdays and two weekend days using the MTI accelerometer, and average percent of time in moderate-to-vigorous PA (MVPA) and time spent sedentary were derived. Potential correlates were assessed by self-report. Independent associations between self-reported correlates with percent time in MVPA and percent time sedentary were analysed by general linear models, adjusted by age, gender, country, measurement period, monitored days and parental socio-economic status.ResultsIn 9-year-olds, playing outdoors after school was associated with higher percent time in MVPA (P < 0.01), while participation in sport clubs was associated with higher percent time in MVPA (P < 0.01) in 15-year-olds. No associations with percent time sedentary were observed in either age group.ConclusionFrequency of outdoor play after school is a significant correlate for daily time in MVPA in 9-year-olds, while this correlate is attenuated in favour of participation in sport and exercise in clubs in 15-year-olds. Targeting walking to school or reduced TV viewing time in order to increase time in daily MVPA in children is unlikely to be sufficient. Correlates related to time spent sedentary need further examination.
|
|
| 7. |
- Sardinha, Luis B., et al.
(författare)
-
Objectively measured time spent sedentary is associated with insulin resistance independent of overall and central body fat in 9- to 10-year-old portuguese children
- 2008
-
Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 31:3, s. 569-575
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We examined the independent relationships between objectively measured physical activity and insulin resistance in Portuguese children. RESEARCH DESIGN AND METHODS: This is a school-based, cross-sectional study in 147 randomly selected girls (aged 9.8 +/- 0.3 years; 27.8 +/- 9.3% body fat) and 161 boys (aged 9.8 +/- 0.3 years; 22.0 +/- 9.2% body fat). Physical activity was assessed by the Actigraph accelerometer for 4 days and summarized as time spent sedentary (accelerometer counts <500/min), in light-intensity (accelerometer counts 500-2,000/min), and in moderate- and vigorous-intensity activity (accelerometer counts >2,001/min). We measured total and central fat mass by dual-energy X-ray absorptiometry. Insulin resistance was expressed as the homeostasis model assessment score. RESULTS: Time (min/day) spent sedentary was significantly and positively associated with insulin resistance (beta-coefficient = 0.001 [95% CI 0.0002-0.002]; P = 0.013). Time spent in moderate- and vigorous-intensity physical activity (-0.002 [-0.003 to -0.001]; P = 0.0009) and overall physical activity (-0.001 [-0.008 to 0.003]; P < 0.0001) were significantly and inversely associated with insulin resistance. All associations remained statistically significant, although they were attenuated after further adjustments for sex, birth weight, sexual maturity, and total or central fat mass (P < 0.03). CONCLUSIONS: Physical activity is associated with insulin resistance independent of total and central fat mass in children. Our results emphasize the importance of decreasing sedentary behavior and increasing time spent in moderate- and vigorous-intensity activity in children, which may have beneficial effects on metabolic risk factors regardless of the degree of adiposity.
|
|
