Temporal patterns of physical activity and sedentary behavior in 10-14 year-old children on weekdays

Background: An important but often ignored aspect of physical activity (PA) and sedentary behavior (SB) is the chronological succession of activities, or temporal pattern. The main purposes of this study were (1) to investigate when certain types of PA and SB compete against each other during the course of the day and (2) compare intensity-and domain-specific activity levels during different day-segments. Methods: The study sample consists of 211 children aged 10-14, recruited from 15 primary and 15 secondary schools. PA was assessed combining the SenseWear Mini Armband (SWM) with an electronic activity diary. The intensity-and domain-specific temporal patterns were plotted and PA differences between different day-segments (i.e., morning, school, early evening and late evening) were examined using repeated-measures ANCOVA models. Results: Physical activity level (PAL) was highest during the early evening (2.51 METSWM) and school hours (2.49 METSWM); the late evening segment was significantly less active (2.21 METSWM) and showed the highest proportion of sedentary time (54 % of total time-use). Throughout the different day-segments, several domains of PA and SB competed with each other. During the critical early-evening segment, screentime (12 % of time-use) and homework (10 %) were dominant compared to activity domains of sports (4 %) and active leisure (3 %). The domain of active travel competed directly with motor travel during the morning (5 % and 6 % respectively) and early-evening segment (both 8 %). Conclusions: Throughout the day, different aspects of PA and SB go in competition with each other, especially during the time period immediately after school. Detailed information on the temporal patterns of PA and SB of children could help health professionals to develop more effective PA interventions and promotion strategies. By making adaptations to the typical day schedule of children (e.g., through the introduction of extra-curricular PA after school hours), their daily activity levels might improve

Phenocopy of a heterozygous carrier of X-linked retinitis pigmentosa due to mosaicism for a RHO variant

We describe both phenotype and pathogenesis in two male siblings with typical retinitis pigmentosa (RP) and the potentially X-linked RP (XLRP) carrier phenotype in their mother. Two affected sons, two unaffected daughters, and their mother underwent detailed ophthalmological assessments including Goldmann perimetry, color vision testing, multimodal imaging and ISCEV-standard electroretinography. Genetic testing consisted of targeted next-generation sequencing (NGS) of known XLRP genes and whole exome sequencing (WES) of known inherited retinal disease genes (RetNet-WES). Variant validation and segregation analysis were performed by Sanger sequencing. The mutational load of the RHO variant in the mother was assessed in DNA from leucocytes, buccal cells and hair follicles using targeted NGS. Both affected sons showed signs of classical RP, while the mother displayed patches of hyperautofluorescence on blue light autofluorescence imaging and regional, intraretinal, spicular pigmentation, reminiscent of a carrier phenotype of XLRP. XLRP testing was negative. RetNet-WES testing revealed RHO variant c.404G>C p.(Arg135Pro) in a mosaic state (21% of the reads) in the mother and in a heterozygous state in both sons. Targeted NGQSS of the RHO variant in different maternal tissues showed a mutation load between 25.06% and 41.72%. We report for the first time that somatic mosaicism of RHO variant c.404G>C p.(Arg135Pro) mimics the phenotype of a female carrier of XLRP, in combination with heterozygosity for the variant in the two affected sons

Elevated urinary excretion of free pyridinoline in Friesian horses suggests a breed-specific increase in collagen degradation

Background: Friesian horses are known for their high inbreeding rate resulting in several genetic diseases such as hydrocephaly and dwarfism. This last decade, several studies focused on two other presumed hereditary traits in Friesian horses: megaoesophagus and aortic rupture. The pathogenesis of these diseases remains obscure but an important role of collagen has been hypothesized. The purpose of this study was to examine possible breed-related differences in collagen catabolism. Urinary specimens from Friesian (n = 17, median age 10 years old) and Warmblood horses (n = 17, median age 10 years old) were assessed for mature collagen cross-links, i.e. pyridinoline (PYD) (=hydroxylysylpyridinoline/HP) and deoxypyridinoline (DPD) (lysylpyridinoline /LP). Solid-phase extraction was performed, followed by reversed-phase ion-paired liquid chromatography prior to tandem mass spectrometry (MS/MS) detection. Results: Mean urinary concentrations of free PYD, expressed as fPYD/creatinine ratio, were significantly higher in Friesian horses compared to Warmblood horses (28.5 ± 5.2 versus 22.2 ± 9.6 nmol/mmol, p = 0.02) while mean fDPD/creatinine ratios were similar in both horse breeds (3.0 ± 0.7 versus 4.6 ± 3.7 nmol/mmol, p = 0.09). Conclusions: Since DPD is considered a specific bone degradation marker and PYD is more widely distributed in connective tissues, the significant elevation in the mean PYD/DPD ratio in Friesian versus Warmblood horses (9.6 ± 1.6 versus 5.7 ± 1.8, p < 0.0001) suggests a soft tissue origin for the increased fPYD levels. Considering that a previous study found no differences in total collagen content between Friesian and Warmblood horses for tendon and aortic tissue, this indicates a higher rate of collagen degradation. The latter might, at least in part, explain the predisposition of Friesians to connective tissue disorders

Biallelic sequence and structural variants in RAX2 are a novel cause for autosomal recessive inherited retinal disease.

Purpose RAX2 encodes a homeobox-containing transcription factor, in which four monoallelic pathogenic variants have been described in autosomal dominant cone-dominated retinal disease. Methods Exome sequencing in a European cohort with inherited retinal disease (IRD) (n = 2086) was combined with protein structure modeling of RAX2 missense variants, bioinformatics analysis of deletion breakpoints, haplotyping of RAX2 variant c.335dup, and clinical assessment of biallelic RAX2-positive cases and carrier family members. Results Biallelic RAX2 sequence and structural variants were found in five unrelated European index cases, displaying nonsyndromic autosomal recessive retinitis pigmentosa (ARRP) with an age of onset ranging from childhood to the mid-40s (average mid-30s). Protein structure modeling points to loss of function of the novel recessive missense variants and to a dominant-negative effect of the reported dominant RAX2 alleles. Structural variants were fine-mapped to disentangle their underlying mechanisms. Haplotyping of c.335dup in two cases suggests a common ancestry. Conclusion This study supports a role for RAX2 as a novel disease gene for recessive IRD, broadening the mutation spectrum from sequence to structural variants and revealing a founder effect. The identification of biallelic RAX2 pathogenic variants in five unrelated families shows that RAX2 loss of function may be a nonnegligible cause of IRD in unsolved ARRP cases

Patterns of daily physical activity and sedentary behavior in Flemish youth

Regular physical activity plays an important role in the normal development of children and provides beneficial effects on body composition, cardiovascular risk factors, bone health and mental well-being. Despite these benefits, epidemiological evidence indicates that activity levels decrease during the course of childhood and adolescence. This age-related decline of physical activity behavior is especially noticeable during early adolescence, a period in the lifetime of children that coincides with the transition from primary to secondary school. Accurate and detailed epidemiological information on the current activity levels of children is essential to fully understand the age-related decrease of physical activity behavior and to counter it through effective physical activity interventions and public health policy. The greater part of the studies that have examined physical activity patterns during childhood have used self-report techniques to quantify physical activity behavior. However, because of cognitive immaturity and intermittent activity patterns, children often experience difficulties remembering their past physical activity behavior. Consequently, retrospective self-report techniques are not the most appropriate tools to accurately assess physical activity behavior in children. In recent years, physical activity research in youth has evolved towards objective assessment using activity monitors. In the current research project two assessment techniques were combined (i.e. the SenseWear Mini Armband and an electronic activity diary) in order to obtain a more detailed and comprehensive image on patterns of physical activity and sedentary behavior of 10 to 14 year-old children. The project consists of two interrelated chapters regarding the objective assessment of physical activity and sedentary behavior in children and adolescents. The first chapter addresses methodological aspects of physical activity assessment in children using the SenseWear Mini Armband. In the second chapter, levels and patterns of physical activity and sedentary behavior are investigated in detail together with their relation with components of health-related fitness. The aim of the methodological chapter was to examine the validity of the SenseWear Mini Armband for the estimation of energy expenditure and to establish device-specific intensity thresholds for the SenseWear Mini Armband in children. The results indicated that the SenseWear Mini underestimated energy expenditure across the intensity spectrum. At the higher end of the intensity spectrum (i.e. very vigorous activities) a leveling off in energy expenditure estimation was observed. Given the high correlation between energy expenditure estimates of the SenseWear Mini Armband and the criterion, intensity thresholds were determined to discriminate between sedentary, light, moderate and vigorous intensity activities in 10 to 14 year-olds. The findings from this methodological paper were used to optimize the assessment accuracy of a 7-day physical activity monitoring protocol in the second chapter of the research project In the first paper of the epidemiological chapter, intensity- and domain-specific levels of physical activity and sedentary behavior were established in a sample of 10 to 14 year-olds. Moreover, differences in physical activity and sedentary behavior between week versus weekend days, genders and school stages were examined. The results indicated that activity levels were higher on weekdays compared with weekend days. In general, boys were more active than girls and primary school children more active than secondary school children. Nonetheless, differences in intensity- and domain-specific activity levels revealed meaningful nuances that are important for the development of physical activity interventions and promotion strategies. The second paper described and examined temporal patterns of physical activity and sedentary behavior on weekdays in our sample. The temporal pattern of physical activity and sedentary behavior was similar for boys and girls and for primary and secondary school children. The analysis indicated that at several time points during the day different types of physical activity and sedentary behavior go into competition with each other, most often in favor of sedentary pursuits. Moreover, the typical day schedule of children obstructs them to be active during the period immediately after school, also known as the ‘critical hours’ of physical activity behavior. By making adaptation to the typical day schedule of children, their daily activity levels might improve. In the final paper of this research project, the associations between objectively assessed components of physical activity and health-related fitness were investigated. The aim was to more precisely establish the link between physical activity and health-related physical fitness by addressing some of the constraints from earlier studies. In general, small-to-moderate associations were observed between components of physical activity behavior and health-related fitness. However, the associations between physical activity behavior and health-related fitness were stronger in girls compared with boys. Time spent sedentary and at light intensity activity was more strongly related to health-related fitness compared with moderate and vigorous physical activity. All together, the findings from the different papers highlight the importance of taking into account the complexity and multidimensionality of physical activity behavior 1) for the assessment for physical activity in field-based research, 2) for the description and interpretation of physical activity data and 3) for the development of physical activity interventions and promotion strategies in youth.nrpages: 182status: publishe

Associations between Objectively Assessed Components of Physical Activity and Health-Related Fitness in 10- to 14-Year-Old Children

BACKGROUND:Our aim was to investigate the association between different components of physical activity (PA) and health-related fitness in 10-to 14-year-old children. METHODS:241 children were recruited from 15 primary and 15 secondary schools. PA was assessed using the SenseWear Mini and an electronic diary. Health-related fitness was assessed using Eurofit and translated into indicators of body fatness, cardiorespiratory fitness and muscular fitness. Associations between PA intensity and physical fitness components were determined using multiple linear regression models adjusted for possible confounders and the contribution of PA domains per intensity categories was calculated. RESULTS:Associations between PA intensities and body fatness were low to moderate (|β|=0.09-0.44), explaining up to 6% of the variance in boys and 17% in girls. For cardiorespiratory fitness, associations were higher (|β|=0.17-0.56), with PA explaining up to 6% of the variance in boys and 31% in girls. Low-to-moderate associations (|β|=0.06-0.43) were found for muscular fitness, with PA explaining up to 7% in boys and 13% in girls. Stronger associations were found for sedentary and light activities. CONCLUSIONS:Low-to-moderate associations between PA and fitness components were observed, with higher associations in girls. Sedentary and light intensity activity showed the strongest link with body fatness, cardiorespiratory fitness and muscular fitness.status: publishe

Results from Flanders' 2018 Report Card on Physical Activity for Children and Youth

status: publishe

Associations between objectively assessed components of physical activity and health-related fitness in 10- to 14-year-old children

Background: Our aim was to investigate the association between different components of physical activity (PA) and health-related fitness in 10-to 14-year-old children. Methods: 241 children were recruited from 15 primary and 15 secondary schools. PA was assessed using the SenseWear Mini and an electronic diary. Health-related fitness was assessed using Eurofit and translated into indicators of body fatness, cardiorespiratory fitness and muscular fitness. Associations between PA intensity and physical fitness components were determined using multiple linear regression models adjusted for possible confounders and the contribution of PA domains per intensity categories was calculated. Results: Associations between PA intensities and body fatness were low to moderate (vertical bar beta vertical bar = 0.09 to 0.44), explaining up to 6% of the variance in boys and 17% in girls. For cardiorespiratory fitness, associations were higher (vertical bar beta vertical bar = 0.17 to 0.56), with PA explaining up to 6% of the variance in boys and 31% in girls. Low-to-moderate associations (vertical bar beta vertical bar = 0.06 to 0.43) were found for muscular fitness, with PA explaining up to 7% in boys and 13% in girls. Stronger associations were found for sedentary and light activities. Conclusions: Low-to-moderate associations between PA and fitness components were observed, with higher associations in girls. Sedentary and light intensity activity showed the strongest link with body fatness, cardiorespiratory fitness and muscular fitness