Publications by authors named "Susi Kriemler"

143 Publications

Effects of acetazolamide on pulmonary artery pressure and prevention of high altitude pulmonary edema after rapid active ascent to 4,559 m.

J Appl Physiol (1985) 2022 May 5. Epub 2022 May 5.

Pulmonary, Critical Care and Sleep Medicine, VA Puget Sound Health Care System, University of Washington, Seattle, WA, United States.

Acetazolamide prevents acute mountain sickness (AMS) by inhibition of carbonic anhydrase. Since it reduces acute hypoxic pulmonary vasoconstriction (HPV), it may also prevent high-altitude pulmonary edema (HAPE) by lowering pulmonary artery pressure. We tested this hypothesis in a randomized, placebo-controlled, double-blind study. Thirteen healthy, non-acclimatized lowlanders with a history of HAPE ascended (<22h) from 1,130 to 4,559m with one overnight stay at 3,611m. Medications started 48h before ascent (acetazolamide: n=7, 250mg 3x/d; placebo: n=6, 3x/d). HAPE was diagnosed by chest radiography, and pulmonary artery pressure by measurement of right ventricular to atrial pressure gradient (RVPG) by transthoracic echocardiography. AMS was evaluated with the Lake Louise Score (LLS) and AMS-C Score. Incidence of HAPE was 43% vs. 67% (acetazolamide vs. placebo, p=0.39). Ascent to altitude increased RVPG from 20±5 to 43±10mmHg (p<0.001) without a group difference (p=0.68). Arterial PO fell to 36±9mmHg (p<0.001) and was 8.5mmHg higher with acetazolamide at high altitude (p=0.025). At high altitude, the LLS and AMS-C score remained lower in those taking acetazolamide (both p<0.05). Although acetazolamide reduced HAPE incidence by 35%, this effect was not statistically significant, and considerably less than reductions of about 70-100% with prophylactic dexamethasone, tadalafil, and nifedipine performed with the same ascent profile at the same location. We could not demonstrate a reduction in RVPG compared to placebo treatment despite reductions in AMS severity and better arterial oxygenation. Limited by a small sample size, our data do not support recommending acetazolamide for prevention of HAPE in mountaineers ascending rapidly to over 4,500m.
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http://dx.doi.org/10.1152/japplphysiol.00806.2021DOI Listing
May 2022

Associations between measures of physical fitness and cognitive performance in preschool children.

BMC Sports Sci Med Rehabil 2022 May 1;14(1):80. Epub 2022 May 1.

Division of Training and Movement Sciences, University of Potsdam, Potsdam, Germany.

Background: Given that recent studies report negative secular declines in physical fitness, associations between fitness and cognition in childhood are strongly discussed. The preschool age is characterized by high neuroplasticity which effects motor skill learning, physical fitness, and cognitive development. The aim of this study was to assess the relation of physical fitness and attention (including its individual dimensions (quantitative, qualitative)) as one domain of cognitive performance in preschool children. We hypothesized that fitness components which need precise coordination compared to simple fitness components are stronger related to attention.

Methods: Physical fitness components like static balance (i.e., single-leg stance), muscle strength (i.e., handgrip strength), muscle power (i.e., standing long jump), and coordination (i.e., hopping on one leg) were assessed in 61 healthy children (mean age 4.5 ± 0.6 years; girls n = 30). Attention was measured with the "Konzentrations-Handlungsverfahren für Vorschulkinder" [concentration-action procedure for preschoolers]). Analyses were adjusted for age, body height, and body mass.

Results: Results from single linear regression analysis revealed a significant (p < 0.05) association between physical fitness (composite score) and attention (composite score) (standardized ß = 0.40), showing a small to medium effect (F = 0.14). Further, coordination had a significant relation with the composite score and the quantitative dimension of attention (standardized ß = 0.35; p < 0.01; standardized ß =  - 0.33; p < 0.05). Coordination explained about 11% (composite score) and 9% (quantitative dimension) of the variance in the stepwise multiple regression model.

Conclusion: The results indicate that performance in physical fitness, particularly coordination, is related to attention in preschool children. Thus, high performance in complex fitness components (i.e., hopping on one leg) tends to predict attention in preschool children. Further longitudinal studies should focus on the effectiveness of physical activity programs implementing coordination and complex exercises at preschool age to examine cause-effect relationships between physical fitness and attention precisely.
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http://dx.doi.org/10.1186/s13102-022-00470-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9063064PMC
May 2022

The Physical Activity and Fitness in Childhood Cancer Survivors (PACCS) Study: Protocol for an International Mixed Methods Study.

JMIR Res Protoc 2022 Mar 8;11(3):e35838. Epub 2022 Mar 8.

Department of Pediatric Hematology and Oncology, Oslo University Hospital, Oslo, Norway.

Background: Survivors of childhood cancer represent a growing population with a long life expectancy but high risks of treatment-induced morbidity and premature mortality. Regular physical activity (PA) may improve their long-term health; however, high-quality empirical knowledge is sparse.

Objective: The Physical Activity and Fitness in Childhood Cancer Survivors (PACCS) study comprises 4 work packages (WPs) aiming for the objective determination of PA and self-reported health behavior, fatigue, and quality of life (WP 1); physical fitness determination (WP 2); the evaluation of barriers to and facilitators of PA (WP 1 and 3); and the feasibility testing of an intervention to increase PA and physical fitness (WP 4).

Methods: The PACCS study will use a mixed methods design, combining patient-reported outcome measures and objective clinical and physiological assessments with qualitative data gathering methods. A total of 500 survivors of childhood cancer aged 9 to 18 years with ≥1 year after treatment completion will be recruited in follow-up care clinics in Norway, Denmark, Finland, Germany, and Switzerland. All participants will participate in WP 1, of which approximately 150, 40, and 30 will be recruited to WP 2, WP3, and WP 4, respectively. The reference material for WP 1 is available from existing studies, whereas WP 2 will recruit healthy controls. PA levels will be measured using ActiGraph accelerometers and self-reports. Validated questionnaires will be used to assess health behaviors, fatigue, and quality of life. Physical fitness will be measured by a cardiopulmonary exercise test, isometric muscle strength tests, and muscle power and endurance tests. Limiting factors will be identified via neurological, pulmonary, and cardiac evaluations and the assessment of body composition and muscle size. Semistructured, qualitative interviews, analyzed using systematic text condensation, will identify the perceived barriers to and facilitators of PA for survivors of childhood cancer. In WP 4, we will evaluate the feasibility of a 6-month personalized PA intervention with the involvement of local structures.

Results: Ethical approvals have been secured at all participating sites (Norwegian Regional Committee for Medical Research Ethics [2016/953 and 2018/739]; the Oslo University Hospital Data Protection Officer; equivalent institutions in Finland, Denmark [file H-19032270], Germany, and Switzerland [Ethics Committee of Northwestern and Central Switzerland, project ID: 2019-00410]). Data collection for WP 1 to 3 is complete. This will be completed by July 2022 for WP 4. Several publications are already in preparation, and 2 have been published.

Conclusions: The PACCS study will generate high-quality knowledge that will contribute to the development of an evidence-based PA intervention for young survivors of childhood cancer to improve their long-term care and health. We will identify physiological, psychological, and social barriers to PA that can be targeted in interventions with immediate benefits for young survivors of childhood cancer in need of rehabilitation.

International Registered Report Identifier (irrid): DERR1-10.2196/35838.
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http://dx.doi.org/10.2196/35838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8941432PMC
March 2022

Influence of Guideline Operationalization on Youth Activity Prevalence in the International Children's Accelerometry Database.

Med Sci Sports Exerc 2022 Feb 21. Epub 2022 Feb 21.

Centre for Diet and Activity Research (CEDAR) & MRC Epidemiology Unit, University of Cambridge, Cambridge, UNITED KINGDOM School of Health Promotion and Human Performance, Eastern Michigan University, Ypsilanti, Michigan School of Heath Sciences, University of East Anglia, East Anglia, UNITED KINGDOM Norwegian School of Sport Sciences, Oslo, NORWAY School of Sports, Exercise and Health Sciences, Loughborough University, Loughborough, UNITED KINGDOM Faculty of Education, Arts and Sport, Western Norway University of Applied Sciences, Sogndal, NORWAY Health Research Institute, University of Canberra, Canberra, AUSTRALIA Federal University of Pelotas, Pelotas, BRAZIL Centre for Exercise, Nutrition & Health Sciences, School for Policy Studies, University of Bristol, UNITED KINGDOM Epidemiology, Biostatistics and Public Health Institute, University of Zürich, Zürich, SWITZERLAND Department of Sports Science and Clinical Biomechanics, Research Unit for Exercise Epidemiology, Centre of Research in Childhood Health, University of Southern Denmark, Odense, DENMARK Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago Bristol Medical School, University of Bristol, Bristol, UNITED KINGDOM Department of Exercise Science, University of South Carolina, Columbia, SC Institute for Physical Activity and Nutrition & School of Exercise and Nutrition Sciences, Deakin University, Geelong, AUSTRALIA Exercise and Health Laboratory, CIPER, Faculty of Human Kinetics, Universidade de Lisboa, Lisbon, PORTUGAL.

Introduction: The United Kingdom and World Health Organization recently changed their youth physical activity (PA) guidelines from 60 minutes of moderate-vigorous PA (MVPA) every day, to an average of 60 minutes of MVPA per day, over a week. The changes are based on expert opinion due to insufficient evidence comparing health outcomes associated with different guideline definitions. This study used the International Children's Accelerometry Database to compare approaches to calculating youth PA compliance and associations with health indicators.

Methods: Cross-sectional accelerometer data (n = 21,612, 5-18y) was used to examine compliance with four guideline definitions: daily method (DM; ≥60 minutes MVPA every day), average method (AM; average of ≥60 minutes MVPA per day), AM5 (AM compliance and ≥ five minutes of vigorous PA [VPA] on ≥three days), AM15 (AM compliance and ≥ 15 minutes VPA on ≥three days). Associations between compliance and health indicators were examined for all definitions.

Results: Compliance varied from 5·3% (DM) to 29·9% (AM). Associations between compliance and health indicators were similar for AM, AM5, and AM15. For example, compliance with AM, AM5, and AM15 was associated with a lower BMI z-score (statistics are coefficient [95%CI]): AM (-0.28[-0.33,-0.23]), AM5 (-0.28[-0.33,-0.23], AM15 (-0.30[-0.35,-0.25]). Associations between compliance and health indicators for DM were similar/weaker, possibly reflecting fewer DM-compliant participants with health data and lower variability in exposure/outcome data.

Conclusions: Youth completing 60 minutes of MVPA every day do not experience superior health benefits to youth completing an average of 60 minutes of MVPA per day. Guidelines should encourage youth to achieve an average of 60 minutes of MVPA per day. Different guideline definitions impact inactivity prevalence estimates; this must be considered when analyzing data and comparing studies.
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http://dx.doi.org/10.1249/MSS.0000000000002884DOI Listing
February 2022

[Opportunities in Differentiated School Sports Exemption - Results of An Online-Survey and Review of the Literature].

Klin Padiatr 2022 Feb 9. Epub 2022 Feb 9.

Pediatric Cardiology, Private Practice at Herz-Jesu-Krankenhaus, Fulda, Germany.

Background: Physical education and sports participation in school play a major role in overall activity of children and adolescents. A differentiated school sports exemption (DSE) allows sports participation adapted to the individual's ability.

Method: Online-survey among physicians (2019) and physical education (PE) teachers (in two waves, 2017 and 2019), on their opinion towards the concept of DSE with respect to professional and demographic parameters. Answers were scaled on a 6-point Likert scale. Means and 95% confidence intervals (95%-CI) were calculated.

Results: Complete questionnaires of 97 physicians and 280 teachers were included. A mean of 10,3% (95%-CI: 9,5-11,1%) of students, did not participate in PE class. In most cases, students were excused directly by their parents without consulting a physician. Most frequent reasons for exemption were missing sports gear (62%), common colds (54%), or acute injuries (50%). Chronic disease or disability was rare (8%). Most teachers did not feel well prepared to deal with children with chronic diseases or disabilities in PE class. Many physicians (24%) had never considered DSE. However, the concept was well accepted among both physicians and teachers. It was considered more practicable than exemption from being marked.

Discussion: According to participants, DSE is expedient and feasible. As a secondary option, students with chronic disease or disability may be exempted from being marked in PE class by their physician.

Conclusion: The concept of DSE was widely accepted, but rarely used. It can be applied in various scenarios. In order to improve sports participation, a national standardized procedure should to be implemented.
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http://dx.doi.org/10.1055/a-1721-2755DOI Listing
February 2022

Cross-sectional and prospective associations of sleep duration and bedtimes with adiposity and obesity risk in 15 810 youth from 11 international cohorts.

Pediatr Obes 2022 04 1;17(4):e12873. Epub 2021 Dec 1.

Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway.

Objectives: To investigate associations of bedtimes and sleep durations with adiposity levels in children and adolescents.

Methods: Individual data were pooled for 12 247 children (5819 with follow-up adiposity at 2.3 ± 1.4 years post-baseline) and 3563 adolescents from 11 international studies. Associations between questionnaire-based sleep durations, bedtimes and four groups of combined bedtimes and sleep lengths (later-shorter [reference]/earlier-shorter/later-longer/earlier-longer) with measured adiposity (body mass index [BMI] and waist circumference z-scores) and weight status, were investigated.

Results: In children, longer sleep durations were consistently associated with lower adiposity markers, and earlier bedtimes were related to lower BMI z-score. Compared to sleeping <10 h, longer baseline sleep duration favourably predicted Δwaist z-score in girls (≥10 and <11 h (β-coefficient (95% confidence interval [CI])): -0.06 (-0.12 to -0.01)) and boys (≥11 h: -0.10 [-0.18 to -0.01]). Combined groups that were defined by longer sleep (later-longer and earlier-longer sleep patterns) were associated with lower adiposity, and later-longer sleep favourably predicted Δwaist z-score in girls (-0.09 [-0.15 to -0.02]). In adolescents, longer sleep durations and earlier bedtimes were associated with lower BMI z-score in the whole sample, and also with lower waist z-score in boys. Combined groups that were characterized by earlier bedtimes were associated with the same outcomes. For example, earlier-shorter (-0.22 (-0.43 to -0.01) and earlier-longer (-0.16 (-0.25 to -0.06) sleep were both associated with lower BMI z-score.

Conclusions: If the associations are causal, longer sleep duration and earlier bedtimes should be targeted for obesity prevention, emphasizing longer sleep for children and earlier bedtimes for adolescents.
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http://dx.doi.org/10.1111/ijpo.12873DOI Listing
April 2022

Evolution of SARS-CoV-2 seroprevalence and clusters in school children from June 2020 to April 2021: prospective cohort study Ciao Corona.

Swiss Med Wkly 2021 10 12;151:w30092. Epub 2021 Nov 12.

Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Switzerland

Background: Few studies have explored the spread of SARS-CoV-2 in schools in 2021, with the advent of variants of concern. We aimed to examine the evolution of the proportion of seropositive children at schools from June-July 2020 to March-April 2021. We also examined symptoms, under-detection of infections, potential preventive effect of face masks, and reasons for non-participation in the study.

Methods: Children in lower (7–10 years), middle (8–13 years) and upper (12–17 years) school levels in randomly selected schools and classes in the canton of Zurich, Switzerland, were invited to participate in the prospective cohort study Ciao Corona. Three testing rounds were completed in June-July 2020, October-November 2020 and March-April 2021. From 5230 invited, 2974 children from 275 classes in in 55 schools participated in at least one testing round. We measured SARS-CoV-2 serology in venous blood, and parents filled in questionnaires on sociodemographic information and symptoms.

Results: The proportion of children seropositive for SARS-CoV-2 increased from 1.5% (95% credible interval [CrI] 0.6–2.6%) by June-July 2020, to 6.6% (4.0–8.9%) by October-November, and to 16.4% (12.1–19.5%) by March-April 2021. By March-April 2021, children in upper school level (12.4%; 7.3–16.7%) were less likely to be seropositive than those in middle (19.5%; 14.2–24.4%) or lower school levels (16.0%; 11.0–20.4%). The ratio of PCR-diagnosed to all seropositive children changed from one to 21.7 (by June-July 2020) to one to 3.5 (by March-April 2021). Potential clusters of three or more newly seropositive children were detected in 24 of 119 (20%) classes, 17 from which could be expected by chance. Clustering was not higher than expected by chance in middle and upper school levels. Children in the upper school level, who were wearing face masks at school from November 2020, had a 5.1% (95% confidence interval 9.4% to 0.7%) lower than expected seroprevalence by March-April 2021 than those in middle school level, based on difference-in-differences analysis. Symptoms were reported by 37% of newly seropositive and 16% seronegative children. Fear of blood sampling (64%) was the most frequently reported reason for non-participation.

Conclusions: Although the proportion of seropositive children increased from 1.5% in June-July 2020 to 16.4% in March-April 2021, few infections were likely associated with potential spread within schools. In March-April 2021, significant clustering of seropositive children within classes was observed only in the lower school level.
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http://dx.doi.org/10.4414/smw.2021.w30092DOI Listing
October 2021

Effects of a Partially Supervised Conditioning Program in Cystic Fibrosis: An International Multicenter, Randomized Controlled Trial (ACTIVATE-CF).

Am J Respir Crit Care Med 2022 02;205(3):330-339

Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland.

The long-term effects of vigorous physical activity (PA) on lung function in cystic fibrosis are unclear. To evaluate effects of a 12-month partially supervised PA intervention using motivational feedback. In a parallel-arm multicenter randomized controlled trial (ACTIVATE-CF), relatively inactive patients aged at least 12 years were randomly assigned (1:1 ratio) to an intervention group or control group. The intervention group consented to add 3 hours of vigorous PA per week, whereas the control group was asked not to change their PA behavior. Primary endpoint was change in percent predicted FEV (ΔFEV) at 6 months. Secondary endpoints included PA, exercise capacity, exercise motives, time to first exacerbation and exacerbation rates, quality of life, anxiety, depression, stress, and blood glucose control. Data were analyzed using mixed linear models. A total of 117 patients (40% of target sample size) were randomized to an intervention (n = 60) or control group (n = 57). After 6 months, ΔFEV was significantly higher in the control group compared with the intervention group (2.70% predicted [95% confidence interval, 0.13-5.26];  = 0.04). The intervention group reported increased vigorous PA compared with the control group at each study visit, had higher exercise capacity at 6 and 12 months, and higher PA at 12 months. No effects were seen in other secondary outcomes. ACTIVATE-CF increased vigorous PA and exercise capacity, with effects carried over for the subsequent 6 months, but resulted in better FEV in the control group.
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http://dx.doi.org/10.1164/rccm.202106-1419OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8887001PMC
February 2022

Association of change in the school travel mode with changes in different physical activity intensities and sedentary time: A International Children's Accelerometry Database Study.

Prev Med 2021 12 26;153:106862. Epub 2021 Oct 26.

MRC Epidemiology Unit and Centre for Diet and Activity Research (CEDAR), University of Cambridge, Cambridge, UK. Electronic address:

Our aim was to assess the association between changes in active travel to school and changes in different intensities of physical activity (i.e. moderate - MPA and vigorous - VPA) and time spent sedentary (SED) among adolescents and assess the moderating effect of children's sex, age and weight status. Data from six cohort studies in the International Children's Accelerometry Database were used (4108 adolescents aged 10-13y at baseline, with 1.9±0.7y of follow-up). Participants self-reported travel mode to school at baseline and follow-up. Mutually exclusive categories of change were created using passive (e.g. by car) or active (cycling or walking) forms of transport (active/active, passive/active, active/passive, passive/passive). Multilevel linear regression analyses assessed associations with change in accelerometer-assessed time spent MPA, VPA and SED, adjusting for potential confounders. The moderation of sex, age and weight status was tested though the inclusion of interaction terms in the regression models. Relative to those remaining in active travel (active/active), participants classified as passive/active increased VPA (B: 2.23 min/d; 95%CI: 0.97-3.48), while active/passive (MPA: -5.38min/d; -6.77 to -3.98; VPA: -2.92min/d; -4.06 to -1.78) and passive/passive (MPA: -4.53min/d; -5.55 to -3.50; VPA: -2.84min/d; -3.68 to -2.01) decreased MPA and VPA. There were no associations with SED. An interaction was observed, age group moderated the association with change in VPA: among 12-13y-olds a greater increase in VPA was observed for the passive/active group compared to active/active. Promoting active travel to school can be a strategy to attenuate the decline in physical activity through adolescence.
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http://dx.doi.org/10.1016/j.ypmed.2021.106862DOI Listing
December 2021

Prediction of Past SARS-CoV-2 Infections: A Prospective Cohort Study Among Swiss Schoolchildren.

Front Pediatr 2021 16;9:710785. Epub 2021 Aug 16.

Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland.

To assess the predictive value of symptoms, sociodemographic characteristics, and SARS-CoV-2 exposure in household, school, and community setting for SARS-CoV-2 seropositivity in Swiss schoolchildren at two time points in 2020. Serological testing of children in primary and secondary schools (aged 6-13 and 12-16 years, respectively) took place in June-July (T1) and October-November (T2) 2020, as part of the longitudinal, school-based study in the canton of Zurich, Switzerland. Information on sociodemographic characteristics and clinical history was collected with questionnaires to parents; information on school-level SARS-CoV-2 infections was collected with questionnaires to school principals. Community-level cumulative incidence was obtained from official statistics. We used logistic regression to identify individual predictors of seropositivity and assessed the predictive performance of symptom- and exposure-based prediction models. A total of 2,496 children (74 seropositive) at T1 and 2,152 children (109 seropositive) at T2 were included. Except for anosmia (odds ratio 15.4, 95% confidence interval [3.4-70.7]) and headache (2.0 [1.03-3.9]) at T2, none of the individual symptoms were significantly predictive of seropositivity at either time point. Of all the exposure variables, a reported SARS-CoV-2 case in the household was the strongest predictor for seropositivity at T1 (12.4 [5.8-26.7]) and T2 (10.8 [4.5-25.8]). At both time points, area under the receiver operating characteristic curve was greater for exposure-based (T1, 0.69; T2, 0.64) than symptom-based prediction models (T1, 0.59; T2, 0.57). In children, retrospective identification of past SARS-CoV-2 infections based on symptoms is imprecise. SARS-CoV-2 seropositivity is better predicted by factors of SARS-CoV-2 exposure, especially reported SARS-CoV-2 cases in the household. Predicting SARS-CoV-2 seropositivity in children in general is challenging, as few reliable predictors could be identified. For an accurate retrospective identification of SARS-CoV-2 infections in children, serological tests are likely indispensable. NCT04448717.
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http://dx.doi.org/10.3389/fped.2021.710785DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8415623PMC
August 2021

Walking onset: a poor predictor for motor and cognitive skills in healthy preschool children.

BMC Pediatr 2021 08 27;21(1):367. Epub 2021 Aug 27.

Child Development Center, University Children's Hospital Zurich, Zurich, Switzerland.

Background: The onset of walking is thought to be an indicator of early development. However, evidence is mixed and clear data on this relationship at preschool age is missing. The study aimed at investigating if walking onset and motor and cognitive development in preschool children are related.

Methods: A total of 555 children (mean age 3.86 years) of the Swiss Preschoolers' Health Study SPLASHY were tested twice at their childcare center (at baseline and one year later). Motor skills and cognitive skills were assessed by standardized testing procedures and parents were asked to provide information on walking onset of their child.

Results: Late onset of walking was related to poorer motor skills (fine motor skills, static and dynamic balance (all p < 0.003)) and poorer cognitive skills (selective attention and visual perception (p = 0.02; p = 0.001) in late preschool age.

Conclusions: For children with late walking onset a close monitoring of their development in the regular pediatric child health visits may be reasonable.

Trial Registration: ISRCTN41045021 .
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http://dx.doi.org/10.1186/s12887-021-02828-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8393818PMC
August 2021

Variation in SARS-CoV-2 seroprevalence across districts, schools and classes: baseline measurements from a cohort of primary and secondary school children in Switzerland.

BMJ Open 2021 07 26;11(7):e047483. Epub 2021 Jul 26.

Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland

Objectives: To determine the variation in SARS-CoV-2 seroprevalence in school children and the relationship with self-reported symptoms.

Design: Baseline measurements of a longitudinal cohort study () from June to July 2020.

Setting: 55 schools stratified by district in the canton of Zurich, Switzerland.

Participants: 2585 children (1339 girls; median age: 11 years, age range: 6-16 years), attending grades 1-2, 4-5 and 7-8.

Main Outcome Measures: Variation in seroprevalence of SARS-CoV-2 in children across 12 cantonal districts, schools and grades, assessed using Luminex-based test of four epitopes for IgG, IgA and IgM (Antibody Coronavirus Assay,ABCORA 2.0). Clustering of cases within classes. Association of seropositivity and symptoms. Comparison with seroprevalence in adult population, assessed using Luminex-based test of IgG and IgA (Sensitive Anti-SARS-CoV-2 Spike Trimer Immunoglobulin Serological test).

Results: Overall seroprevalence was 2.8% (95% CI 1.5% to 4.1%), ranging from 1.0% to 4.5% across districts. Seroprevalence in grades 1-2 was 3.8% (95% CI 2.0% to 6.1%), in grades 4-5 was 2.4% (95% CI 1.1% to 4.2%) and in grades 7-8 was 1.5% (95% CI 0.5% to 3.0%). At least one seropositive child was present in 36 of 55 (65%) schools and in 44 (34%) of 131 classes where ≥5 children and ≥50% of children within the class were tested. 73% of children reported COVID-19-compatible symptoms since January 2020, with the same frequency in seropositive and seronegative children for all symptoms. Seroprevalence of children and adults was similar (3.2%, 95% credible interval (CrI) 1.7% to 5.0% vs 3.6%, 95% CrI 1.7% to 5.4%). The ratio of confirmed SARS-CoV-2 cumulative incidence-to-seropositive cases was 1:89 in children and 1:12 in adults.

Conclusions: SARS-CoV-2 seroprevalence was low in children and similar to that in adults by the end of June 2020. Very low ratio of diagnosed-to-seropositive children was observed. We did not detect clustering of SARS-CoV-2-seropositive children within classes, but the follow-up of this study will shed more light on transmission within schools.

Trial Registration Number: NCT04448717.
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http://dx.doi.org/10.1136/bmjopen-2020-047483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8316698PMC
July 2021

Long-term Symptoms After SARS-CoV-2 Infection in Children and Adolescents.

JAMA 2021 Jul 15. Epub 2021 Jul 15.

Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Zurich, Switzerland.

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http://dx.doi.org/10.1001/jama.2021.11880DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8283661PMC
July 2021

Reference values and validation of the 1-minute sit-to-stand test in healthy 5-16-year-old youth: a cross-sectional study.

BMJ Open 2021 05 7;11(5):e049143. Epub 2021 May 7.

Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland

Objectives: It is essential to have simple, reliable and valid tests to measure children's functional capacity in schools or medical practice. The 1-minute sit-to-stand (STS) test is a quick fitness test requiring little equipment or space that is increasingly used in both healthy populations and those with chronic disease. We aimed to provide age-specific and sex-specific reference values of STS test in healthy children and adolescents and to evaluate its short-term reliability and construct validity.

Design Setting And Participants: Cross-sectional convenience sample from six public schools and one science fair in central Europe. Overall, 587 healthy participants aged 5-16 years were recruited and divided into age groups of 3 years each.

Outcomes: 1-minute STS. To evaluate short-term reliability, some children performed the STS test twice. To evaluate construct validity, some children also performed a standing long jump (SLJ) and a maximal incremental exercise test.

Results: Data from 547 youth aged 5-16 years were finally included in the analyses. The median number of repetitions in 1 min in males (females) ranged from 55 [95% CI: 38 to 72] (53 [95% CI: 35 to 76]) in 14-16-year olds to 59 [95% CI: 41 to 77] (60 [95% CI: 38 to 77]) in 8-10-year olds. Children who repeated STS showed a learning effect of on average 4.8 repetitions more than the first test (95% limits of agreement: -6.7 to 16.4). Moderate correlations were observed between the STS and the SLJ (r=0.48) tests and the maximal exercise test (r=0.43).

Conclusions: The reported STS reference values can be used to interpret STS test performance in children and adolescents. The STS appears to have good test-retest reliability, but a learning effect of about 10%. The association of STS with other measures of physical fitness should be further explored in a larger study and technical standards for its conduct are needed.
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http://dx.doi.org/10.1136/bmjopen-2021-049143DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8108674PMC
May 2021

Surveillance of Acute SARS-CoV-2 Infections in School Children and Point-Prevalence During a Time of High Community Transmission in Switzerland.

Front Pediatr 2021 16;9:645577. Epub 2021 Mar 16.

Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland.

Switzerland had one of the highest incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in Europe during the second wave. Schools were open as in most of Europe with specific preventive measures in place. However, the frequency and transmission of acute unrecognized, asymptomatic or oligosymptomatic infections in schools during this time of high community transmission is unknown. Thereof, our aim was to pilot a surveillance system that detects acute SARS-CoV-2 infections in schools and possible transmission within classes. Fourteen out of the randomly selected sample of the cohort study participated between December 1 and 11, a time when incidence rate for SARS-CoV-2 infections was high for the canton of Zurich. We determined point-prevalence of acute SARS-CoV-2 infections of school children attending primary and secondary school. A buccal swab for polymerase chain reaction (PCR) and a rapid diagnostic test (RDT) to detect SARS-CoV-2 were taken twice 1 week apart (T1 and T2) in a cohort of children from randomly selected classes. A questionnaire assessed demographics and symptoms compatible with a SARS-CoV-2 infection during the past 5 days. Out of 1,299 invited children, 641 (49%) 6- to 16-year-old children and 66 teachers from 14 schools and 67 classes participated in at least one of two testings. None of the teachers but one child had a positive PCR at T1, corresponding to a point-prevalence in children of 0.2% (95% CI 0.0-1.1%), and no positive PCR was detected at T2. The child with positive PCR at T1 was negative on the RDT at T1 and both tests were negative at T2. There were 7 (0.6%) false positive RDTs in children and 2 (1.7%) false positive RDTs in teachers at T1 or T2 among 5 schools (overall prevalence 0.7%). All 9 initially positive RDTs were negative in a new buccal sample taken 2 h to 2 days later, also confirmed by PCR. Thirty-five percent of children and 8% of teachers reported mild symptoms during the 5 days prior to testing. In a setting of high incidence of SARS-CoV-2 infections, unrecognized virus spread within schools was very low. Schools appear to be safe with the protective measures in place (e.g., clearly symptomatic children have to stay at home, prompt contact tracing with individual and class-level quarantine, and structured infection prevention measures in school). Specificity of the RDT was within the lower boundary of performance and needs further evaluation for its use in schools. Given the low point prevalence even in a setting of very high incidence, a targeted test, track, isolate and quarantine (TTIQ) strategy for symptomatic children and school personnel adapted to school settings is likely more suitable approach than surveillance on entire classes and schools. https://clinicaltrials.gov/ct2/show/NCT04448717, ClinicalTrials.gov NCT04448717.
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http://dx.doi.org/10.3389/fped.2021.645577DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8007924PMC
March 2021

Effects of a Strength-Dominated Exercise Program on Physical Fitness and Cognitive Performance in Preschool Children.

J Strength Cond Res 2021 Apr;35(4):983-990

Division of Training and Movement Sciences, University of Potsdam, Potsdam, Germany; and.

Abstract: Wick, K, Kriemler, S, and Granacher, U. Effects of a strength-dominated exercise program on physical fitness and cognitive performance in preschool children. J Strength Cond Res 35(4): 983-990, 2021-Childhood is characterized by high neuroplasticity that affords qualitative rather than quantitative components of physical activity to maximize the potential to sufficiently develop motor skills and foster long-term engagement in regular physical activity. This study examined the effects of an integrative strength-dominated exercise program on measures of physical fitness and cognitive performance in preschool children. Children aged 4-6 years from 3 kindergartens were randomized into an intervention (INT) group (n = 32) or a control group (n = 22). The 10-week intervention period was conducted 3 times per week (each session lasted 30 minutes) and included exercises for the promotion of muscle strength and power, coordination, and balance. Pre and post training, tests were conducted for the assessment of muscle strength (i.e., handgrip strength), muscle power (i.e., standing long jump), balance (i.e., timed single-leg stand), coordination (hopping on right/left leg), and attentional span (i.e., "Konzentrations-Handlungsverfahren für Vorschulkinder" [concentration-action procedure for preschoolers]). Results from 2 × 2 repeated-measures analysis of covariance revealed a significant (p ≤ 0.05) and near significant (p = 0.051) group × time interaction for the standing long jump test and the Konzentrations-Handlungsverfahren. Post hoc tests showed significant pre-post changes for the INT (p < 0.001; d = 1.53) but not the CON (p = 0.72; d = 0.83). Our results indicate that a 10-week strength-dominated exercise program increased jump performance with a concomitant trend toward improvements in attentional capacity of preschool children. Thus, we recommend implementing this type of exercise program for preschoolers.
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http://dx.doi.org/10.1519/JSC.0000000000003942DOI Listing
April 2021

Clustering and longitudinal change in SARS-CoV-2 seroprevalence in school children in the canton of Zurich, Switzerland: prospective cohort study of 55 schools.

BMJ 2021 03 17;372:n616. Epub 2021 Mar 17.

Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Hirschengraben 84, 8001 Zurich, Switzerland

Objectives: To examine longitudinal changes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence and to determine the clustering of children who were seropositive within school classes in the canton of Zurich, Switzerland from June to November 2020.

Design: Prospective cohort study.

Setting: Switzerland had one of the highest second waves of the SARS-CoV-2 pandemic in Europe in autumn 2020. Keeping schools open provided a moderate to high exposure environment to study SARS-CoV-2 infections. Children from randomly selected schools and classes, stratified by district, were invited for serological testing of SARS-CoV-2. Parents completed questionnaires on sociodemographic and health related questions.

Participants: 275 classes in 55 schools; 2603 children participated in June-July 2020 and 2552 in October-November 2020 (age range 6-16 years).

Main Outcome Measures: Serology of SARS-CoV-2 in June-July and October-November 2020, clustering of children who were seropositive within classes, and symptoms in children.

Results: In June-July, 74 of 2496 children with serological results were seropositive; in October-November, the number had increased to 173 of 2503. Overall SARS-CoV-2 seroprevalence was 2.4% (95% credible interval 1.4% to 3.6%) in the summer and 4.5% (3.2% to 6.0%) in late autumn in children who were not previously seropositive, leading to an estimated 7.8% (6.2% to 9.5%) of children who were ever seropositive. Seroprevalence varied across districts (in the autumn, 1.7-15.0%). No significant differences were found among lower, middle, and upper school levels (children aged 6-9 years, 9-13 years, and 12-16 years, respectively). Among the 2223 children who had serology tests at both testing rounds, 28/70 (40%) who were previously seropositive became seronegative, and 109/2153 (5%) who were previously seronegative became seropositive. Symptoms were reported for 22% of children who were seronegative and 29% of children who were newly seropositive since the summer. Between July and November 2020, the ratio of children diagnosed with SARS-CoV-2 infection to those who were seropositive was 1 to 8. At least one child who was newly seropositive was detected in 47 of 55 schools and in 90 of 275 classes. Among 130 classes with a high participation rate, no children who were seropositive were found in 73 (56%) classes, one or two children were seropositive in 50 (38%) classes, and at least three children were seropositive in 7 (5%) classes. Class level explained 24% and school level 8% of variance in seropositivity in the multilevel logistic regression models.

Conclusions: With schools open since August 2020 and some preventive measures in place, clustering of children who were seropositive occurred in only a few classes despite an increase in overall seroprevalence during a period of moderate to high transmission of SARS-CoV-2 in the community. Uncertainty remains as to whether these findings will change with the new variants of SARS-CoV-2 and dynamic levels of community transmission.

Trial Registration: NCT04448717.
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http://dx.doi.org/10.1136/bmj.n616DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7966948PMC
March 2021

Children's moderate-to-vigorous physical activity on weekdays versus weekend days: a multi-country analysis.

Int J Behav Nutr Phys Act 2021 02 10;18(1):28. Epub 2021 Feb 10.

MRC Epidemiology Unit & Centre for Diet and Activity Research, University of Cambridge, Cambridge, UK.

Purpose: The Structured Days Hypothesis (SDH) posits that children's behaviors associated with obesity - such as physical activity - are more favorable on days that contain more 'structure' (i.e., a pre-planned, segmented, and adult-supervised environment) such as school weekdays, compared to days with less structure, such as weekend days. The purpose of this study was to compare children's moderate-to-vigorous physical activity (MVPA) levels on weekdays versus weekend days using a large, multi-country, accelerometer-measured physical activity dataset.

Methods: Data were received from the International Children's Accelerometer Database (ICAD) July 2019. The ICAD inclusion criteria for a valid day of wear, only non-intervention data (e.g., baseline intervention data), children with at least 1 weekday and 1 weekend day, and ICAD studies with data collected exclusively during school months, were included for analyses. Mixed effects models accounting for the nested nature of the data (i.e., days within children) assessed MVPA minutes per day (min/day MVPA) differences between weekdays and weekend days by region/country, adjusted for age, sex, and total wear time. Separate meta-analytical models explored differences by age and country/region for sex and child weight-status.

Results/findings: Valid data from 15 studies representing 5794 children (61% female, 10.7 ± 2.1 yrs., 24% with overweight/obesity) and 35,263 days of valid accelerometer data from 5 distinct countries/regions were used. Boys and girls accumulated 12.6 min/day (95% CI: 9.0, 16.2) and 9.4 min/day (95% CI: 7.2, 11.6) more MVPA on weekdays versus weekend days, respectively. Children from mainland Europe had the largest differences (17.1 min/day more MVPA on weekdays versus weekend days, 95% CI: 15.3, 19.0) compared to the other countries/regions. Children who were classified as overweight/obese or normal weight/underweight accumulated 9.5 min/day (95% CI: 6.9, 12.2) and 10.9 min/day (95% CI: 8.3, 13.5) of additional MVPA on weekdays versus weekend days, respectively.

Conclusions: Children from multiple countries/regions accumulated significantly more MVPA on weekdays versus weekend days during school months. This finding aligns with the SDH and warrants future intervention studies to prioritize less-structured days, such as weekend days, and to consider providing opportunities for all children to access additional opportunities to be active.
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http://dx.doi.org/10.1186/s12966-021-01095-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7877033PMC
February 2021

School-based interventions modestly increase physical activity and cardiorespiratory fitness but are least effective for youth who need them most: an individual participant pooled analysis of 20 controlled trials.

Br J Sports Med 2021 Jan 13. Epub 2021 Jan 13.

Department of Sport Science, Nottingham Trent University, Nottingham, Nottinghamshire, UK.

Objectives: To determine if subpopulations of students benefit equally from school-based physical activity interventions in terms of cardiorespiratory fitness and physical activity. To examine if physical activity intensity mediates improvements in cardiorespiratory fitness.

Design: Pooled analysis of individual participant data from controlled trials that assessed the impact of school-based physical activity interventions on cardiorespiratory fitness and device-measured physical activity.

Participants: Data for 6621 children and adolescents aged 4-18 years from 20 trials were included.

Main Outcome Measures: Peak oxygen consumption (VO mL/kg/min) and minutes of moderate and vigorous physical activity.

Results: Interventions modestly improved students' cardiorespiratory fitness by 0.47 mL/kg/min (95% CI 0.33 to 0.61), but the effects were not distributed equally across subpopulations. Girls and older students benefited less than boys and younger students, respectively. Students with lower levels of initial fitness, and those with higher levels of baseline physical activity benefitted more than those who were initially fitter and less active, respectively. Interventions had a modest positive effect on physical activity with approximately one additional minute per day of both moderate and vigorous physical activity. Changes in vigorous, but not moderate intensity, physical activity explained a small amount (~5%) of the intervention effect on cardiorespiratory fitness.

Conclusions: Future interventions should include targeted strategies to address the needs of girls and older students. Interventions may also be improved by promoting more vigorous intensity physical activity. Interventions could mitigate declining youth cardiorespiratory fitness, increase physical activity and promote cardiovascular health if they can be delivered equitably and their effects sustained at the population level.
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http://dx.doi.org/10.1136/bjsports-2020-102740DOI Listing
January 2021

Physical fitness and modifiable cardiovascular disease risk factors in survivors of childhood cancer: A report from the SURfit study.

Cancer 2021 05 6;127(10):1690-1698. Epub 2021 Jan 6.

Pediatric Oncology/Hematology, University Children's Hospital Basel, Basel, Switzerland.

Background: Childhood cancer survivors are at risk for cardiovascular disease (CVD) because of intensive cancer therapies often accompanied by an unhealthy lifestyle. This study was aimed at 1) describing modifiable CVD risk factors in survivors and 2) investigating the association between different aspects of physical fitness and CVD risk factors.

Methods: The authors analyzed cross-sectional data from ≥5-year survivors who were 16 years old or younger at their cancer diagnosis and 16 years old or older at the time of the study. Single CVD risk factors (waist circumference, blood pressure, fasting glucose, inverse high-density lipoprotein, and triglycerides), a composite CVD risk score (combined z scores of all CVD risk factors), and metabolic syndrome were evaluated. Physical fitness measures included cardiopulmonary exercise testing (CPET), a handgrip test, and a 1-minute sit-to-stand test (STS). Multivariable logistic regression was used for the association between fitness measures and CVD risk factors, with adjustments made for demographic factors and cancer therapy.

Results: This study included 163 survivors with a median age at diagnosis of 7 years and a median age at the time of the study of 28 years. Among those survivors, 27% had a high waist circumference, 32% had high blood pressure, 19% had high triglycerides, 20% had an increased composite CVD risk score, and 10% had metabolic syndrome. A better performance during CPET, handgrip testing, and STS was associated with a lower probability of having a high waist circumference, high triglycerides, and metabolic syndrome.

Conclusions: Better aerobic fitness (CPET) and, to a lesser extent, handgrip and STS were associated with fewer CVD risk factors. Further investigations are warranted to investigate which fitness measures should preferably be used to screen survivors to promote physical activity in those with impaired test performance.

Lay Summary: This study investigated the relationship between physical fitness of adult childhood cancer survivors and their risk factors for cardiovascular disease. Cardiovascular risk factors such as high blood pressure, a high waist circumference, and high blood lipids were frequently found in childhood cancer survivors. Survivors with better physical fitness (measured by a cycling test or simple strength and endurance tests) had a lower chance of having cardiovascular risk factors. This suggests that childhood cancer survivors could benefit from physical activity and general fitness by increasing their physical fitness and possibly decreasing their risk of cardiovascular disease.
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http://dx.doi.org/10.1002/cncr.33351DOI Listing
May 2021

An Update on Secular Trends in Physical Fitness of Children and Adolescents from 1972 to 2015: A Systematic Review.

Sports Med 2021 Feb;51(2):303-320

Division of Training and Movement Sciences, Research Focus Cognition Sciences, University of Potsdam, Am Neuen Palais 10, Building 12, 14469, Potsdam, Germany.

Background: There is evidence that physical fitness of children and adolescents (particularly cardiorespiratory endurance) has declined globally over the past decades. Ever since the first reports on negative trends in physical fitness, efforts have been undertaken by for instance the World Health Organization (WHO) to promote physical activity and fitness in children and adolescents. Therefore, it is timely to re-analyze the literature to examine whether previous reports on secular declines in physical fitness are still detectable or whether they need to be updated.

Objectives: The objective of this systematic review is to provide an 'update' on secular trends in selected components of physical fitness (i.e., cardiorespiratory endurance, relative muscle strength, proxies of muscle power, speed) in children and adolescents aged 6-18 years.

Data Sources: A systematic computerized literature search was conducted in the electronic databases PubMed and Web of Science to locate studies that explicitly reported secular trends in physical fitness of children and adolescents.

Study Eligibility Criteria: Studies were included in this systematic review if they examined secular trends between at least two time points across a minimum of 5 years. In addition, they had to document secular trends in any measure of cardiorespiratory endurance, relative muscle strength, proxies of muscle power or speed in apparently healthy children and adolescents aged 6-18 years.

Study Appraisal And Synthesis Methods: The included studies were coded for the following criteria: nation, physical fitness component (cardiorespiratory endurance, relative muscle strength, proxies of muscle power, speed), chronological age, sex (boys vs. girls), and year of assessment. Scores were standardized (i.e., converted to z scores) with sample-weighted means and standard deviations, pooled across sex and year of assessment within cells defined by study, test, and children's age.

Results: The original search identified 524 hits. In the end, 22 studies met the inclusion criteria for review. The observation period was between 1972 and 2015. Fifteen of the 22 studies used tests for cardiorespiratory endurance, eight for relative muscle strength, eleven for proxies of muscle power, and eight for speed. Measures of cardiorespiratory endurance exhibited a large initial increase and an equally large subsequent decrease, but the decrease appears to have reached a floor for all children between 2010 and 2015. Measures of relative muscle strength showed a general trend towards a small increase. Measures of proxies of muscle power indicated an overall small negative quadratic trend. For measures of speed, a small-to-medium increase was observed in recent years.

Limitations: Biological maturity was not considered in the analysis because biological maturity was not reported in most included studies.

Conclusions: Negative secular trends were particularly found for cardiorespiratory endurance between 1986 and 2010-12, irrespective of sex. Relative muscle strength and speed showed small increases while proxies of muscle power declined. Although the negative trend in cardiorespiratory endurance appears to have reached a floor in recent years, because of its association with markers of health, we recommend further initiatives in PA and fitness promotion for children and adolescents. More specifically, public health efforts should focus on exercise that increases cardiorespiratory endurance to prevent adverse health effects (i.e., overweight and obesity) and muscle strength to lay a foundation for motor skill learning.
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http://dx.doi.org/10.1007/s40279-020-01373-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7846517PMC
February 2021

Seroprevalence and immunity of SARS-CoV-2 infection in children and adolescents in schools in Switzerland: design for a longitudinal, school-based prospective cohort study.

Int J Public Health 2020 Dec 15;65(9):1549-1557. Epub 2020 Oct 15.

Epidemiology, Biostatistics and Prevention Institute (EBPI), University of Zurich, Hirschengraben 84, 8001, Zurich, Switzerland.

Objectives: This longitudinal cohort study aims to assess the extent and patterns of seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in school-attending children, and their parents and school personnel. It will examine risk factors for infection, the relationship between seropositivity and symptoms, and temporal persistence of antibodies.

Methods: The study (Ciao Corona) will enroll a regionally representative, random sample of schools in the canton of Zurich, where 18% of the Swiss population live. Children aged 5-16 years, attending primary and secondary schools, and their parents and school personnel are invited. Venous blood and saliva samples are collected for serological testing in June/July 2020, in October/November 2020, and in March/April 2021. Bi-monthly questionnaires will cover SARS-CoV-2 symptoms and tests, health, preventive behavior, and lifestyle information. Hierarchical Bayesian logistic regression models will account for sensitivity and specificity of the serological tests in the analyses and complex sampling structure, i.e., clustering within classes and schools.

Results And Conclusions: This unique school-based study will allow describing temporal trends of immunity, evaluate effects of preventive measures and will inform goal-oriented policy decisions during subsequent outbreaks. Trial registration ClinicalTrials.gov Identifier: NCT04448717, registered June 26, 2020. https://clinicaltrials.gov/ct2/show/NCT04448717 .
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http://dx.doi.org/10.1007/s00038-020-01495-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7561232PMC
December 2020

The multivariate physical activity signature associated with metabolic health in children and youth: An International Children's Accelerometry Database (ICAD) analysis.

Prev Med 2020 12 3;141:106266. Epub 2020 Oct 3.

Department of Sport, Food and Natural Sciences, Faculty of Education, Arts and Sports, Western Norway University of Applied Sciences, Sogndal, Norway. Electronic address:

There is solid evidence for an association between physical activity and metabolic health outcomes in children and youth, but for methodological reasons most studies describe the intensity spectrum using only a few summary measures. We aimed to determine the multivariate physical activity intensity signature associated with metabolic health in a large and diverse sample of children and youth, by investigating the association pattern for the entire physical intensity spectrum. We used pooled data from 11 studies and 11,853 participants aged 5.8-18.4 years included in the International Children's Accelerometry Database. We derived 14 accelerometry-derived (ActiGraph) physical activity variables covering the intensity spectrum (from 0-99 to ≥8000 counts per minute). To handle the multicollinearity among these variables, we used multivariate pattern analysis to establish the associations with indices of metabolic health (abdominal fatness, insulin sensitivity, lipid metabolism, blood pressure). A composite metabolic health score was used as the main outcome variable. Associations with the composite metabolic health score were weak for sedentary time and light physical activity, but gradually strengthened with increasing time spent in moderate and vigorous intensities (up to 4000-5000 counts per minute). Association patterns were fairly consistent across sex and age groups, but varied across different metabolic health outcomes. This novel analytic approach suggests that vigorous intensity, rather than less intense activities or sedentary behavior, are related to metabolic health in children and youth.
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http://dx.doi.org/10.1016/j.ypmed.2020.106266DOI Listing
December 2020

The causal pathway effects of a physical activity intervention on adiposity in children: The KISS Study cluster randomized clinical trial.

Scand J Med Sci Sports 2020 Sep 22;30(9):1685-1691. Epub 2020 Jun 22.

Epidemiology, Biostatistics and Prevention Institute, University of Zürich, Zürich, Switzerland.

Background: Very little information on the potential mechanisms of the physical activity interventions effects on adiposity is available. We evaluated the possible mediating factors of a physical activity school-based intervention on the sum of skinfolds in children.

Methods: This is a cluster randomized trial, secondary analysis of the KISS study. Children (n = 499) from the first and fifth grades were randomly assigned to intervention or control group. Adiposity was estimated by four skinfolds, aerobic fitness assessed by the shuttle run test, and insulin, triglycerides, total cholesterol, high-density lipoprotein (HDL), and glucose collected via fasting blood samples.

Results: The intervention affected aerobic fitness (0.140 SD, 95% CI 0.011 to 0.270), triglycerides (0.217 SD, 95% CI -0.409 to -0.025), cholesterol/HDL ratio (-0.191 SD, 95% CI -0.334 to -0.047), glucose (-0.330 SD, 95% CI -0.538 to -0.121), and skinfolds (-0.122 SD, 95% CI -0.189 to -0.056). No intervention effect on insulin was found. We observed that changes in aerobic fitness impacted children's triglycerides and cholesterol/HDL ratio and consecutively the glucose levels mediating 30% of the intervention effect on skinfolds.

Conclusions: Our findings provided evidence of the positive metabolic distress caused by a physical activity intervention on adiposity levels in children.
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http://dx.doi.org/10.1111/sms.13741DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496602PMC
September 2020

Birth weight, cardiometabolic risk factors and effect modification of physical activity in children and adolescents: pooled data from 12 international studies.

Int J Obes (Lond) 2020 10 3;44(10):2052-2063. Epub 2020 Jun 3.

Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway.

Objectives: Low and high birth weight is associated with higher levels of cardiometabolic risk factors and adiposity in children and adolescents, and increases the risk of cardiovascular diseases, obesity, and early mortality later in life. Moderate-to-vigorous physical activity (MVPA) is associated with lower cardiometabolic risk factors and may mitigate the detrimental consequences of high or low birth weight. Thus, we examined whether MVPA modified the associations between birth weight and cardiometabolic risk factors in children and adolescents.

Methods: We used pooled individual data from 12 cohort- or cross-sectional studies including 9,100 children and adolescents. Birth weight was measured at birth or maternally reported retrospectively. Device-measured physical activity (PA) and cardiometabolic risk factors were measured in childhood or adolescence. We tested for associations between birth weight, MVPA, and cardiometabolic risk factors using multilevel linear regression, including study as a random factor. We tested for interaction between birth weight and MVPA by introducing the interaction term in the models (birth weight x MVPA).

Results: Most of the associations between birth weight (kg) and cardiometabolic risk factors were not modified by MVPA (min/day), except between birth weight and waist circumference (cm) in children (p = 0.005) and HDL-cholesterol (mmol/l) in adolescents (p = 0.040). Sensitivity analyses suggested that some of the associations were modified by VPA, i.e., the associations between birth weight and diastolic blood pressure (mmHg) in children (p = 0.009) and LDL- cholesterol (mmol/l) (p = 0.009) and triglycerides (mmol/l) in adolescents (p = 0.028).

Conclusion: MVPA appears not to consistently modify the associations between low birth weight and cardiometabolic risk. In contrast, MVPA may mitigate the association between higher birth weight and higher waist circumference in children. MVPA is consistently associated with a lower cardiometabolic risk across the birth weight spectrum. Optimal prenatal growth and subsequent PA are both important in relation to cardiometabolic health in children and adolescents.
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http://dx.doi.org/10.1038/s41366-020-0612-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7508671PMC
October 2020

Cardiac vagal tone in preschool children: Interrelations and the role of stress exposure.

Int J Psychophysiol 2020 06 14;152:102-109. Epub 2020 Apr 14.

Clinical Psychology and Psychotherapy, Department of Psychology, University of Fribourg, Fribourg, Switzerland. Electronic address:

Introduction: Cardiac vagal tone has been understood as the biological correlate of emotion regulation and can be divided into emotion regulation (tonic cardiac vagal tone (TCVT)) and the flexibility to adapt to changing conditions (phasic cardiac vagal tone (PCVT)). There is evidence that TCVT influences PCVT dynamics in adults and that stress exposure impacts on cardiac vagal tone in adults and older children. The aim of the study was to investigate the impact of TCVT on PCVT dynamics in preschoolers and to identify the influence of stress exposures on cardiac vagal tone.

Method: Measures of heart rate variability including baseline (TCVT), during an age-adapted stress task (PCVT stress reactivity) and during recovery (PCVT recovery) were assessed in 222 children aged 2-6 years of the SPLASHY study. Further, parents were asked to complete questionnaires on early stress exposure (including pregnancy, birth and early life) and current stress exposure (including family stress and parenting).

Results: Preschool children with high TCVT showed less PCVT reactivity (p < 0.001) and more increase of vagal tone (PCVT) during early recovery (p = 0.016). Further only child's low birth weight was a relevant stress exposure impacting on early and late PCVT recovery (p = 0.03/p = 0.005). None of the other early or late stress exposure conditions, nor the accumulation of stress exposures influenced TCVT or PCVT dynamics in these healthy preschoolers.

Discussion: TCVT impacts on PCVT dynamics in a lab-based stress task in healthy preschool children and only low birth weight is related to more change during early and to less late PCVT recovery.
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http://dx.doi.org/10.1016/j.ijpsycho.2020.04.006DOI Listing
June 2020

Variations in accelerometry measured physical activity and sedentary time across Europe - harmonized analyses of 47,497 children and adolescents.

Int J Behav Nutr Phys Act 2020 03 18;17(1):38. Epub 2020 Mar 18.

Research Unit for Exercise Epidemiology and Centre of Research in Childhood Health, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.

Background: Levels of physical activity and variation in physical activity and sedentary time by place and person in European children and adolescents are largely unknown. The objective of the study was to assess the variations in objectively measured physical activity and sedentary time in children and adolescents across Europe.

Methods: Six databases were systematically searched to identify pan-European and national data sets on physical activity and sedentary time assessed by the same accelerometer in children (2 to 9.9 years) and adolescents (≥10 to 18 years). We harmonized individual-level data by reprocessing hip-worn raw accelerometer data files from 30 different studies conducted between 1997 and 2014, representing 47,497 individuals (2-18 years) from 18 different European countries.

Results: Overall, a maximum of 29% (95% CI: 25, 33) of children and 29% (95% CI: 25, 32) of adolescents were categorized as sufficiently physically active. We observed substantial country- and region-specific differences in physical activity and sedentary time, with lower physical activity levels and prevalence estimates in Southern European countries. Boys were more active and less sedentary in all age-categories. The onset of age-related lowering or leveling-off of physical activity and increase in sedentary time seems to become apparent at around 6 to 7 years of age.

Conclusions: Two third of European children and adolescents are not sufficiently active. Our findings suggest substantial gender-, country- and region-specific differences in physical activity. These results should encourage policymakers, governments, and local and national stakeholders to take action to facilitate an increase in the physical activity levels of young people across Europe.
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http://dx.doi.org/10.1186/s12966-020-00930-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7079516PMC
March 2020

High impact physical activity and bone health of lower extremities in childhood cancer survivors: A cross-sectional study of SURfit.

Int J Cancer 2020 10 25;147(7):1845-1854. Epub 2020 Mar 25.

Department of Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland.

Childhood cancer survivors (CCS) are at risk of reduced bone health and premature osteoporosis. As physical activity with high impact loading (IL-PA) is known to promote bone health, we compared bone densitometry and microstructure between groups of CCS who performed different amounts of physical activities in their daily life. We used baseline data of a single-center PA trial including 161 CCS from the Swiss Childhood Cancer Registry, aged <16 at diagnosis, ≥16 at study and ≥5 years since diagnosis. Lower body bone health was assessed with peripheral quantitative computed tomography (pQCT) and dual-energy X-ray absorptiometry (DXA). Daily IL-PA (duration in activities >2 g acceleration and numbers of vertical impacts/hr >2 g) was captured using hip-worn accelerometers (1-3 weeks). For both IL-PA approaches, we formed low, middle and high activity groups based on tertiles. Bone health of the high and middle active groups was compared to the low active group. 63% of CCS had indication of at least one bone mineral density z-score ≤ -1 measured by pQCT or DXA. The high IL-PA group performing 2.8 min/day or 19.1 impact peaks/hr > 2 g (median) showed about 3-13% better microstructural and densitometric bone health as compared to the low IL-PA group with 0.38 min/day or 0.85 peaks/hr > 2 g. Just a few minutes and repetitions of high IL-PA as easily modifiable lifestyle factor may be sufficient to improve bone health in adult CCS. Future longitudinal research is needed to better understand pattern and dosage of minimal impact loading needed to strengthen bone in growing and adult CCS.
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http://dx.doi.org/10.1002/ijc.32963DOI Listing
October 2020

Motor Competence and Physical Activity in Early Childhood: Stability and Relationship.

Front Public Health 2020 21;8:39. Epub 2020 Feb 21.

Epidemiology, Biostatistics and Prevention Institute, University of Zurich, Zurich, Switzerland.

Normal motor development and adequate levels of physical activity engagement during the early years of life form the foundation of long-term psychological and physiological health. This is one of the very few studies that investigate the stability and relationships of motor competence and physical activity in preschool children. Baseline and 12 month follow-up data of physical activity and motor competence of 550 preschool children aged 2-6 years from the Swiss Preschoolers' Health Study were used for this work. Physical activity data, expressed in counts per minute for total physical activity and minutes per day for time spent moderately-to-vigorously physically active, were collected over 1 week using accelerometers. Motor competence was assessed with the Zurich Neuromotor Assessment. Both motor competence and physical activity were age- and sex-adjusted. To examine the individual stability of physical activity and motor competence and reciprocal cross-sectional and longitudinal effects between these two domains, a latent variable cross-lagged panel model where motor competence was represented through a latent construct was examined using structural equation modeling. A weak cross-sectional correlation of motor competence with total physical activity ( = 0.24) and moderate-to-vigorous physical activity ( = 0.23) was found. Motor competence exhibited high stability (β = 0.82) in the preschool years and physical activity was moderately stable with estimates ranging from β = 0.37 for total physical activity to β = 0.48 for moderate-to-vigorous physical activity. In contrast to the autoregressive coefficients denoting individual stability, both cross-lagged effects were negligible indicating that physical activity was not a determinant of motor competence or vice versa. Motor competence and physical activity developed independently of each other in early childhood. Although measures of quantity and intensity of physical activity were not related to motor development, specific movement experiences and practice-which are not reflected by accelerometry-may be needed for skill development. Future research should focus on examining what type of physical activity is important for motor development and how to assess it, and also whether the relationship between physical activity and motor competence evolves over time. Current Controlled Trials ISRCTN41045021 (date of registration: 21.03.14).
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http://dx.doi.org/10.3389/fpubh.2020.00039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7047434PMC
May 2021

Associations between accelerometry measured physical activity and sedentary time and the metabolic syndrome: A meta-analysis of more than 6000 children and adolescents.

Pediatr Obes 2020 01 10;15(1):e12578. Epub 2019 Nov 10.

Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.

Background: Metabolic syndrome is increasingly prevalent in the pediatric population. To prevent an early onset, knowledge about its association with modifiable lifestyle factors is needed.

Objectives: To estimate the prevalence of the metabolic syndrome and examine its cross-sectional associations with physical activity and sedentary time.

Methods: Participants were 6009 children and adolescents from 8 studies of the International Children's Accelerometry Database. Physical activity and sedentary time were measured by accelerometer. Metabolic syndrome was defined based on International Diabetes Federation criteria. Logistic regression models adjusted for sex, age and monitor wear time were used to examine the associations between physical activity, sedentary time and the metabolic syndrome in each study and effect estimates were combined using random-effects meta-analysis.

Results: The overall prevalence of the metabolic syndrome was 2.9%. In crude models, a 10 min increase in moderate-to-vigorous intensity physical activity and vigorous-intensity physical activity were inversely associated with the metabolic syndrome [OR 0.88, 95% CI 0.82-0.94, OR 0.80, 95% CI 0.70-0.92]. One hour increase in sedentary time was positively associated with the metabolic syndrome [OR 1.28, 95% CI 1.13-1.45]. After adjustment for sedentary time, the association between moderate-to-vigorous-intensity physical activity and the metabolic syndrome remained significant [OR 0.91, 95% CI 0.84-0.99]. Sedentary time was not associated with the metabolic syndrome after adjustment for moderate-to-vigorous intensity physical activity [OR 1.14 95% CI 0.96-1.36].

Conclusions: Physical activity of at least moderate intensity but not sedentary time is independently associated with the metabolic syndrome.
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http://dx.doi.org/10.1111/ijpo.12578DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7003500PMC
January 2020
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