Effect of Shared Environmental Factors on Exercise Behavior from Age 7 to 12 Years
ABSTRACT The aim of this study was to investigate the relative influence of genetic and environmental factors on children's leisure time exercise behavior through the classic twin design.
Data were taken from The Netherlands Twin Register. The twins were 7 (n = 3966 subjects), 10 (n = 3562), and 12-yr-olds (n = 8687), with longitudinal data for 27% of the sample. Parents were asked to indicate the children's regular participation in leisure time exercise activities, including frequency and duration. Resemblance between monozygotic and dizygotic twins for weekly MET-hours spent on exercise activities was analyzed as a function of their genetic relatedness.
Average weekly MET-hours increased with age for both boys (age 7 yr: 14.0 (SD = 11.8); age 10 yr: 22.6 (SD = 18.7); age 12 yr: 28.4 (SD = 24.9)) and girls (age 7 yr: 9.7 (SD = 9.5); age 10 yr: 15.3 (SD = 15.1); age 12 yr: 19.3 (SD = 19.8)). Around 13% of boys and girls across all age groups did not participate in any regular leisure time exercise activities. Tracking of exercise behavior from age 7 to 12 yr was modest (0.168 < r < 0.534). For boys, genetic effects accounted for 24% (confidence interval, 18%-30%) of the variance at age 7 yr, 66% (53%-81%) at age 10 yr, and 38% (32%-46%) at age 12 yr. For girls, this was 22% (15%-30%), 16% (9%-24%), and 36% (30%-43%), respectively. Environmental influences shared by children from the same family explained 71%, 25%, and 50% of the variance in boys (age 7, 10, and 12 yr) and 67%, 72%, and 53% in girls. The shared environment influencing exercise behavior was partially different between boys and girls.
Our results stress the important role of shared environment for exercise behavior in young children.
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ABSTRACT: Different approaches are being taken to clarify the role of various factors in the development of physical activity behaviors. Genetic studies are a new area of physical activity research and also the motives for physical activity have been widely studied. The purpose of this paper is to review the findings emerging from the longitudinal genetic studies on leisure-time physical activity and to evaluate the associations between motivational factors and leisure-time physical activity. The focus is to review recent findings of longitudinal Finnish twin studies. The results of the latest longitudinal Finnish twin studies point to the existence of age-specific genetic and environmental influences on leisure-time physical activity. Variations in environmental factors seem to explain the observed deterioration in leisure-time physical activity levels. A decline in genetic influences is seen first from adolescence to young adulthood and again from the age of thirty to the mid-thirties. In the Finnish twin participants, mastery, physical fitness, and psychological state were the major motivation factors associated with consistent leisure-time physical activity behavior. The results also indicate that intrinsic motivation factors may be important for engagement in leisure-time physical activity.04/2014; 2014:931820. DOI:10.1155/2014/931820
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ABSTRACT: The Netherlands Twin Register (NTR) began in 1987 with data collection in twins and their families, including families with newborn twins and triplets. Twenty-five years later, the NTR has collected at least one survey for 70,784 children, born after 1985. For the majority of twins, longitudinal data collection has been done by age-specific surveys. Shortly after giving birth, mothers receive a first survey with items on pregnancy and birth. At age 2, a survey on growth and achievement of milestones is sent. At ages 3, 7, 9/10, and 12 parents and teachers receive a series of surveys that are targeted at the development of emotional and behavior problems. From age 14 years onward, adolescent twins and their siblings report on their behavior problems, health, and lifestyle. When the twins are 18 years and older, parents are also invited to take part in survey studies. In sub-groups of different ages, in-depth phenotyping was done for IQ, electroencephalography , MRI, growth, hormones, neuropsychological assessments, and cardiovascular measures. DNA and biological samples have also been collected and large numbers of twin pairs and parents have been genotyped for zygosity by either micro-satellites or sets of short nucleotide polymorphisms and repeat polymorphisms in candidate genes. Subject recruitment and data collection is still ongoing and the longitudinal database is growing. Data collection by record linkage in the Netherlands is beginning and we expect these combined longitudinal data to provide increased insights into the genetic etiology of development of mental and physical health in children and adolescents.Twin Research and Human Genetics 11/2012; 16(1):1-16. DOI:10.1017/thg.2012.118 · 1.92 Impact Factor
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ABSTRACT: Purpose. Twin studies provide evidence that genetic influences contribute strongly to individual differences in exercise behavior. We hypothesize that part of this heritability is explained by genetic variation in the dopaminergic reward system. Eight single nucleotide polymorphisms (SNPs in DRD1: rs265981, DRD2: rs6275, rs1800497, DRD3: rs6280, DRD4: rs1800955, DBH: rs1611115, rs2519152, and in COMT: rs4680) and three variable number of tandem repeats (VNTRs in DRD4, upstream of DRD5, and in DAT1) were investigated for an association with regular leisure time exercise behavior. Materials and Methods. Data on exercise activities and at least one SNP/VNTR were available for 8,768 individuals aged 7 to 50 years old that were part of the Netherlands Twin Register. Exercise behavior was quantified as weekly metabolic equivalents of task (MET) spent on exercise activities. Mixed models were fitted in SPSS with genetic relatedness as a random effect. Results. None of the genetic variants were associated with exercise behavior (P > .02), despite sufficient power to detect small effects. Discussion and Conclusions. We did not confirm that allelic variants involved in dopaminergic function play a role in creating individual differences in exercise behavior. A plea is made for large genome-wide association studies to unravel the genetic pathways that affect this health-enhancing behavior.BioMed Research International 01/2013; 2013:591717. DOI:10.1155/2014/591717 · 2.71 Impact Factor