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Ekelund, Ulf
Publications (10 of 46) Show all publications
Ekelund, U., Luan, J., Sherar, L. B., Esliger, D. W., Griew, P. & Cooper, A. (2012). Moderate to vigorous physical activity and sedentary time and cardiometabolic risk factors in children and adolescents. Journal of the American Medical Association (JAMA), 307(7), 704-712
Open this publication in new window or tab >>Moderate to vigorous physical activity and sedentary time and cardiometabolic risk factors in children and adolescents
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2012 (English)In: Journal of the American Medical Association (JAMA), ISSN 0098-7484, E-ISSN 1538-3598, Vol. 307, no 7, p. 704-712Article in journal (Refereed) Published
Abstract [en]

Context: Sparse data exist on the combined associations between physical activity and sedentary time with cardiometabolic risk factors in healthy children.

Objective: To examine the independent and combined associations between objectively measured time in moderate- to vigorous-intensity physical activity (MVPA) and sedentary time with cardiometabolic risk factors.

Design, Setting, and Participants: Pooled data from 14 studies between 1998 and 2009 comprising 20 871 children (aged 4-18 years) from the International Children's Accelerometry Database. Time spent in MVPA and sedentary time were measured using accelerometry after reanalyzing raw data. The independent associations between time in MVPA and sedentary time, with outcomes, were examined using meta-analysis. Participants were stratified by tertiles of MVPA and sedentary time.

Main Outcome Measures: Waist circumference, systolic blood pressure, fasting triglycerides, high-density lipoprotein cholesterol, and insulin.

Results: Times (mean [SD] min/d) accumulated by children in MVPA and being sedentary were 30 (21) and 354 (96), respectively. Time in MVPA was significantly associated with all cardiometabolic outcomes independent of sex, age, monitor wear time, time spent sedentary, and waist circumference (when not the outcome). Sedentary time was not associated with any outcome independent of time in MVPA. In the combined analyses, higher levels of MVPA were associated with better cardiometabolic risk factors across tertiles of sedentary time. The differences in outcomes between higher and lower MVPA were greater with lower sedentary time. Mean differences in waist circumference between the bottom and top tertiles of MVPA were 5.6 cm (95% CI, 4.8-6.4 cm) for high sedentary time and 3.6 cm (95% CI, 2.8-4.3 cm) for low sedentary time. Mean differences in systolic blood pressure for high and low sedentary time were 0.7 mm Hg (95% CI, -0.07 to 1.6) and 2.5 mmHg (95% CI, 1.7-3.3), and for high-density lipoprotein cholesterol, differences were -2.6 mg/dL(95% CI, -1.4 to -3.9) and -4.5 mg/dL(95% CI, -3.3 to -5.6), respectively. Geometric mean differences for insulin and triglycerides showed similar variation. Those in the top tertile of MVPA accumulated more than 35 minutes per day in this intensity level compared with fewer than 18 minutes per day for those in the bottom tertile. In prospective analyses (N=6413 at 2.1 years' follow-up), MVPA and sedentary time were not associated with waist circumference at follow-up, but a higher waist circumference at baseline was associated with higher amounts of sedentary time at follow-up.

Conclusion: Higher MVPA time by children and adolescents was associated with better cardiometabolic risk factors regardless of the amount of sedentary time.

Place, publisher, year, edition, pages
Chicago, USA: American Medical Association, 2012
National Category
Medical and Health Sciences Pediatrics
Research subject
Medicine
Identifiers
urn:nbn:se:oru:diva-21936 (URN)10.1001/jama.2012.156 (DOI)000300278500027 ()22337681 (PubMedID)2-s2.0-84860711904 (Scopus ID)
Available from: 2012-03-05 Created: 2012-03-05 Last updated: 2017-12-07Bibliographically approved
Armstrong, N., Tomkinson, G. R. & Ekelund, U. (2011). Aerobic fitness and its relationship to sport, exercise training and habitual physical activity during youth. British Journal of Sports Medicine, 45(11), 849-858
Open this publication in new window or tab >>Aerobic fitness and its relationship to sport, exercise training and habitual physical activity during youth
2011 (English)In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 45, no 11, p. 849-858Article in journal (Refereed) Published
Abstract [en]

Aim To analyse aerobic fitness and its relationship with sport participation, exercise training and habitual physical activity (HPA) during youth. Methods Studies were located through computer searches of Medline, SPORT Discus and personal databases. Systematic reviews of time trends in aerobic fitness/performance, and exercise training and peak oxygen uptake (peak VO(2)) are reported. Results Peak VO(2) increases with age and maturation. Boys' peak VO(2) is higher than girls'. Despite data showing a decrease in performance test estimates of aerobic fitness there is no compelling evidence to suggest that young people have low levels of peak VO(2) or that it is declining over time. The primary time constant of the VO(2) kinetics response to moderate and heavy intensity exercise slows with age and the VO(2) kinetics response to heavy intensity exercise is faster in boys. There is a negative correlation between lactate threshold as a percentage of peak VO(2) and age but differences related to maturation or sex remain to be proven. Young athletes have higher peak VO(2), a faster primary time constant and accumulate less blood lactate at the same relative exercise intensity than their untrained peers. Young people can increase their peak VO(2) through exercise training but a meaningful relationship between aerobic fitness and HPA has not been demonstrated. Conclusions During youth the responses of the components of aerobic fitness vary in relation to age, maturation and sex. Exercise training will enhance aerobic fitness but a relationship between young people's current HPA and aerobic fitness remains to be proven.

National Category
Sport and Fitness Sciences
Research subject
Sports Science
Identifiers
urn:nbn:se:oru:diva-18654 (URN)10.1136/bjsports-2011-090200 (DOI)000293787200003 ()
Available from: 2011-09-30 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
Barker, A., Sharp, S. J., Timpson, N. J., Bouatia-Naji, N., Warrington, N. M., Kanoni, S., . . . Langenberg, C. (2011). Association of genetic loci with glucose levels in childhood and adolescence a meta-analysis of over 6,000 children. Diabetes, 60(6), 1805-1812
Open this publication in new window or tab >>Association of genetic loci with glucose levels in childhood and adolescence a meta-analysis of over 6,000 children
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2011 (English)In: Diabetes, ISSN 0012-1797, E-ISSN 1939-327X, Vol. 60, no 6, p. 1805-1812Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE-To investigate whether associations of common genetic variants recently identified for fasting glucose or insulin levels in nondiabetic adults are detectable in healthy children and adolescents. RESEARCH DESIGN AND METHODS-A total of 16 single nucleotide polymorphisms (SNPs) associated with fasting glucose were genotyped in six studies of children and adolescents of European origin, including over 6,000 boys and girls aged 9-16 years. We performed meta-analyses to test associations of individual SNPs and a weighted risk score of the 16 loci with fasting glucose. RESULTS-Nine loci were associated with glucose levels in healthy children and adolescents, with four of these associations reported in previous studies and five reported here for the first time (GLIS3, PROX1, SLC2A2, ADCY5, and CRY2). Effect sizes were similar to those in adults, suggesting age-independent effects of these fasting glucose loci. Children and adolescents carrying glucose-raising alleles of G6PC2, MTNR1B, GCK, and GLIS3 also showed reduced p-cell function, as indicated by homeostasis model assessment of beta-cell function. Analysis using a weighted risk score showed an increase [beta (95% CI)] in fasting glucose level of 0.026 mrnol/L (0.021-0.031) for each unit increase in the score. CONCLUSIONS-Novel fasting glucose loci identified in genome-wide association studies of adults are associated with altered fasting glucose levels in healthy children and adolescents with effect sizes comparable to adults. In nondiabetic adults, fasting glucose changes little over time, and our results suggest that age-independent effects of fasting glucose loci contribute to long-term interindividual differences in glucose levels from childhood onwards. Diabetes 60:1805-1812, 2011

National Category
Sport and Fitness Sciences
Research subject
Sports Science
Identifiers
urn:nbn:se:oru:diva-18701 (URN)10.2337/db10-1575 (DOI)000291369600019 ()
Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
Nyberg, G., Ekelund, U., Yucel-Lindberg, T., Modeer, T. & Marcus, C. (2011). Differences in metabolic risk factors between normal weight and overweight children. International Journal of Pediatric Obesity, 6(3-4), 244-252
Open this publication in new window or tab >>Differences in metabolic risk factors between normal weight and overweight children
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2011 (English)In: International Journal of Pediatric Obesity, ISSN 1747-7166, E-ISSN 1747-7174, Vol. 6, no 3-4, p. 244-252Article in journal (Refereed) Published
Abstract [en]

Background. The effect of overweight on metabolic risk factors and the role of physical activity (PA) in pre-pubertal children is unclear. Objective. To study differences in metabolic risk factors between groups of normal weight and overweight children and how these risk factors are associated with objectively measured PA and cardio-respiratory fitness (CRF). Design. A cross-sectional study was conducted with 68 children aged 8-11 years. Children were categorized into normal weight (n = 39) and overweight/obese (n = 24/5). PA and CRF were measured objectively. An oral glucose tolerance test (OGTT) was performed and triglycerides (TG) and HDL-cholesterol (HDL-C) were measured. A metabolic risk score (MRS) was calculated from the standardized values of insulin, glucose, TG, inverted HDL-C and blood pressure. Results. There was a significant (P < 0.05) difference between normal weight and overweight children in clustered metabolic risk, insulin (AUC), fasting insulin and systolic blood pressure. PA and CRF did not differ significantly between groups. In linear regression analysis combining the two groups, PA was negatively associated with insulin (AUC) (beta = -0.25, 95% CI = -0.50, -0.002) and CRF was negatively associated with fasting insulin (beta = -0.41, 95% CI = -0.67, -0.15). Conclusions. Metabolic risk factors are elevated in overweight pre-pubertal children compared with normal weight controls. This is not explained by lower PA or CRF in the overweight group although PA and CRF were associated with lower insulin levels in pooled analyses. This highlights the importance of preventing overweight in children from an early age in order to prevent the metabolic syndrome and its associated diseases.

Keywords
Accelerometry, BMI, cardio-respiratory fitness, children, physical activity
National Category
Sport and Fitness Sciences
Research subject
Sports Science
Identifiers
urn:nbn:se:oru:diva-20892 (URN)10.3109/17477166.2011.575226 (DOI)000292704900012 ()
Available from: 2012-01-11 Created: 2012-01-11 Last updated: 2017-12-08Bibliographically approved
Ridgway, C. L., Brage, S., Anderssen, S. A., Sardinha, L. B., Andersen, L. B. & Ekelund, U. (2011). Do physical activity and aerobic fitness moderate the association between birth weight and metabolic risk in youth?: The European youth heart study. Diabetes Care, 34(1), 187-192
Open this publication in new window or tab >>Do physical activity and aerobic fitness moderate the association between birth weight and metabolic risk in youth?: The European youth heart study
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2011 (English)In: Diabetes Care, ISSN 0149-5992, E-ISSN 1935-5548, Vol. 34, no 1, p. 187-192Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE- Lower birth weight has been associated with a greater risk of metabolic diseases. The aim of this study was examine whether physical activity and aerobic fitness may modify associations between birth weigh and metabolic risk. RESEARCH DESIGN AND METHODS- The European Youth Heart Study is a population-based study of 9 and 15 year olds (n = 1,254). Birth weight was maternally reported. Skin fold measures were used to calculate body fat and fat mass index (FMI = fat mass [kilograms]/height(2)). Insulin was measured using fasting blood samples. Physical activity was measured using a hip-worn accelerometer (MTI Actigraph) for >600 min/day for >= 3 days and is expressed as "average activity" (counts per minute) and time spent in above moderate intensity activity (>2000 cpm). Aerobic fitness was assessed using a maximal cycle ergometry test (watts per kilogram fat-free mass). RESULTS- Higher birth weight was associated with higher FMI (beta = 0.49 [95% CI 0.21-0.80]; P = 0.001) and greater waist circumference (0.90 [0.32-1.47]; P < 0.001), adjusted for sex, age-group, sexual maturity, height, and socioeconomic status. Lower birth weight was associated with higher fasting insulin only after further adjustment for adolescent waist circumference and height (-0.059 [-0.107 to 0.011]; P = 0.016). There was no evidence for any modification of the associations after adjustment for physical activity or aerobic fitness. CONCLUSIONS- The present study did not find any evidence that physical activity or aerobic fitness can moderate the associations among higher birth weight and increased fat mass and greater waist circumference or between lower birth weight and insulin resistance in healthy children and adolescents.

National Category
Sport and Fitness Sciences
Research subject
Sports Science
Identifiers
urn:nbn:se:oru:diva-18821 (URN)10.2337/dc10-1178 (DOI)000286497000039 ()
Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
Ridgway, C. L., Brage, S., Anderssen, S., Sardinha, L. B., Andersen, L. B. & Ekelund, U. (2011). Fat-free mass mediates the association between birth weight and aerobic fitness in youth. International Journal of Pediatric Obesity, 6(2-2), E590-E596
Open this publication in new window or tab >>Fat-free mass mediates the association between birth weight and aerobic fitness in youth
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2011 (English)In: International Journal of Pediatric Obesity, ISSN 1747-7166, E-ISSN 1747-7174, Vol. 6, no 2-2, p. E590-E596Article in journal (Refereed) Published
Abstract [en]

Objective. To investigate whether birth weight acts as a biological determinant of later aerobic fitness, and whether fat-free mass may mediate this association. Methods. The European Youth Heart Study (EYHS) is a population-based cohort of two age groups (9 and 15 years) from Denmark, Portugal, Estonia and Norway. Children with parentally reported birth weight >1.5 kg were included (n = 2 749). Data were collected on weight, height, and skinfold measures to estimate fat mass and fat-free mass. Aerobic fitness (peak power, watts) was assessed using a maximal, progressive cycle ergometer test. Physical activity was collected in a subset (n = 1 505) using a hip-worn accelerometer and defined as total activity counts/wear time, all children with >600 minutes/day for >= 3 days of wear were included. Results. Lower birth weight was associated with lower aerobic fitness, after adjusting for sex, age group, country, sexual maturity and socio-economic status (beta = 5.4; 95% CI: 3.5, 7.3 W per 1 kg increase in birth weight, p < 0.001). When fat-free mass was introduced as a covariate in the model, the association between birth weight and aerobic fitness was almost completely attenuated (p = 0.7). Birth weight was also significantly associated with fat-free mass (beta = 1.4; 95% CI: 1.1, 1.8, p < 0.001) and fat-free mass was significantly associated with aerobic fitness (beta = 3.6; 95% CI: 3.4, 3.7, p < 0.001). Further adjustment for physical activity did not alter the findings. Conclusion. Birth weight may have long-term influences on fat-free mass and differences in fat-free mass mediate the observed association between birth weight and aerobic fitness.

National Category
Sport and Fitness Sciences
Research subject
Sports Science
Identifiers
urn:nbn:se:oru:diva-18697 (URN)10.3109/17477166.2010.526225 (DOI)000292704500072 ()
Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
Sherar, L. B., Griew, P., Esliger, D. W., Cooper, A. R., Ekelund, U., Judge, K. & Riddoch, C. (2011). International children's accelerometry database (ICAD): design and methods. BMC Public Health, 11, 485
Open this publication in new window or tab >>International children's accelerometry database (ICAD): design and methods
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2011 (English)In: BMC Public Health, ISSN 1471-2458, E-ISSN 1471-2458, Vol. 11, p. 485-Article in journal (Refereed) Published
Abstract [en]

Background: Over the past decade, accelerometers have increased in popularity as an objective measure of physical activity in free-living individuals. Evidence suggests that objective measures, rather than subjective tools such as questionnaires, are more likely to detect associations between physical activity and health in children. To date, a number of studies of children and adolescents across diverse cultures around the globe have collected accelerometer measures of physical activity accompanied by a broad range of predictor variables and associated health outcomes. The International Children's Accelerometry Database (ICAD) project pooled and reduced raw accelerometer data using standardized methods to create comparable outcome variables across studies. Such data pooling has the potential to improve our knowledge regarding the strength of relationships between physical activity and health. This manuscript describes the contributing studies, outlines the standardized methods used to process the accelerometer data and provides the initial questions which will be addressed using this novel data repository. Methods: Between September 2008 and May 2010 46,131 raw Actigraph data files and accompanying anthropometric, demographic and health data collected on children (aged 3-18 years) were obtained from 20 studies worldwide and data was reduced using standardized analytical methods. Results: When using >= 8, >= 10 and >= 12 hrs of wear per day as a criterion, 96%, 93.5% and 86.2% of the males, respectively, and 96.3%, 93.7% and 86% of the females, respectively, had at least one valid day of data. Conclusions: Pooling raw accelerometer data and accompanying phenotypic data from a number of studies has the potential to: a) increase statistical power due to a large sample size, b) create a more heterogeneous and potentially more representative sample, c) standardize and optimize the analytical methods used in the generation of outcome variables, and d) provide a means to study the causes of inter-study variability in physical activity. Methodological challenges include inflated variability in accelerometry measurements and the wide variation in tools and methods used to collect non-accelerometer data.

National Category
Sport and Fitness Sciences
Research subject
Sports Science
Identifiers
urn:nbn:se:oru:diva-18696 (URN)10.1186/1471-2458-11-485 (DOI)000293326900001 ()
Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
Mountjoy, M., Andersen, L. B., Armstrong, N., Biddle, S., Boreham, C., Bedenbeck, H.-P. B., . . . van Mechelen, W. (2011). International Olympic Committee consensus statement on the health and fitness of young people through physical activity and sport. British Journal of Sports Medicine, 45(11), 839-848
Open this publication in new window or tab >>International Olympic Committee consensus statement on the health and fitness of young people through physical activity and sport
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2011 (English)In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 45, no 11, p. 839-848Article in journal (Refereed) Published
National Category
Sport and Fitness Sciences
Research subject
Sports Science
Identifiers
urn:nbn:se:oru:diva-18653 (URN)10.1136/bjsports-2011-090228 (DOI)000293787200002 ()
Available from: 2011-09-30 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
Kilpelaeinen, T. O., den Hoed, M., Ong, K. K., Grontved, A., Brage, S., Jameson, K., . . . Loos, R. J. F. (2011). Obesity-susceptibility loci have a limited influence on birth weight: a meta-analysis of up to 28,219 individuals. American Journal of Clinical Nutrition, 93(4), 851-860
Open this publication in new window or tab >>Obesity-susceptibility loci have a limited influence on birth weight: a meta-analysis of up to 28,219 individuals
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2011 (English)In: American Journal of Clinical Nutrition, ISSN 0002-9165, E-ISSN 1938-3207, Vol. 93, no 4, p. 851-860Article in journal (Refereed) Published
Abstract [en]

Background: High birth weight is associated with adult body mass index (BMI). We hypothesized that birth weight and BMI may partly share a common genetic background. Objective: The objective was to examine the associations of 12 established BMI variants in or near the NEGR1, SEC16B, TMEM18, ETV5, GNPDA2, BDNF, MTCH2, BCDIN3D, SH2B1, FTO, MC4R, and KCTD15 genes and their additive score with birth weight. Design: A meta-analysis was conducted with the use of 1) the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk, Hertfordshire, Fenland, and European Youth Heart Study cohorts (n(max) = 14,060); 2) data extracted from the Early Growth Genetics Consortium meta-analysis of 6 genome-wide association studies for birth weight (n(max) = 10,623); and 3) all published data (n(max) = 14,837). Results: Only the MTCH2 and FTO loci showed a nominally significant association with birth weight. The BMI-increasing allele of the MTCH2 variant (rs10838738) was associated with a lower birth weight (beta +/- SE: 213 +/- 5 g/allele; P = 0.012; n = 23,680), and the BMI-increasing allele of the FTO variant (rs1121980) was associated with a higher birth weight (beta +/- SE: 11 +/- 4 g/allele; P = 0.013; n = 28,219). These results were not significant after correction for multiple testing. Conclusions: Obesity-susceptibility loci have a small or no effect on weight at birth. Some evidence of an association was found for the MTCH2 and FTO loci, ie, lower and higher birth weight, respectively. These findings may provide new insights into the underlying mechanisms by which these loci confer an increased risk of obesity. Am J Clin Nutr 2011;93:851-60.

National Category
Sport and Fitness Sciences
Research subject
Sports Science
Identifiers
urn:nbn:se:oru:diva-18752 (URN)10.3945/ajcn.110.000828 (DOI)000288531600024 ()
Available from: 2011-09-29 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
Ekelund, U., Tomkinson, G. R. & Armstrong, N. (2011). What proportion of youth are physically active?: Measurement issues, levels and recent time trends. British Journal of Sports Medicine, 45(11), 859-865
Open this publication in new window or tab >>What proportion of youth are physically active?: Measurement issues, levels and recent time trends
2011 (English)In: British Journal of Sports Medicine, ISSN 0306-3674, E-ISSN 1473-0480, Vol. 45, no 11, p. 859-865Article in journal (Refereed) Published
Abstract [en]

Aim The aim of this review is to summarise issues surrounding the measurement of physical activity (PA) by self-report and accelerometry in youth (2-18 years old). Current levels and temporal trends in PA and sport participation and the effect of assessment method on data interpretation will be summarised. Methods Relevant papers were extracted from a computerised literature search of MEDLINE and personal databases. Additional papers were extracted from reference lists of recently published reviews. Results The criterion validity (direct comparison with an objective method) of self-reported instruments is low to moderate, with correlation coefficients generally between 0.3 and 0.4. Self-report instruments overestimate the intensity and duration of PA and sport participation. The interpretation of PA data from accelerometry is a challenge, and specific issues include the definition of intensity thresholds and the influence of age on intensity thresholds. Recent data on self-reported PA in youth suggest that between 30% and 40% are sufficiently active. Prevalence values for sufficiently active youth measured by accelerometry range between 1% and 100%, depending on the intensity thresholds used. Sport participation is likely to contribute to higher levels of PA. The available evidence does not support the notion that PA levels and sport participation in youth have declined in recent decades. Conclusion The number of youth meeting current PA guidelines varies by assessment method and the intensity thresholds used when PA is measured by accelerometry. The available evidence does not firmly support the notion that PA in young people has declined during the last decades. It is unlikely that any self-report method is sufficiently accurate for examining cross-cultural differences and temporal trends in young people's PA and sport participation over time. Surveillance systems therefore need to strive for an international standardisation using objective measurements of PA to complement existing self-report instruments.

National Category
Sport and Fitness Sciences
Research subject
Sports Science
Identifiers
urn:nbn:se:oru:diva-18655 (URN)10.1136/bjsports-2011-090190 (DOI)000293787200004 ()
Available from: 2011-09-30 Created: 2011-09-29 Last updated: 2017-12-08Bibliographically approved
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