Genetic confounding in the association of early motor development with childhood and adolescent exercise behavior.

INTRODUCTION: Early motor development has been found to be a predictor of exercise behavior in children and adolescents, but whether this reflects a causal effect or confounding by genetic or shared environmental factors remains to be established. METHODS: For 20,911 complete twin pairs from the Netherlands Twin Register a motor development score was obtained from maternal reports on the timing of five motor milestones. During a 12-year follow-up, subsamples of the mothers reported on the twins' ability to perform seven gross motor skills ability (N = 17,189 pairs), and weekly minutes of total metabolic equivalents of task (MET) spent on sports and exercise activities at age 7 (N = 3632 pairs), age 10 (N = 3735 pairs), age 12 (N = 7043 pairs), and age 14 (N = 3990 pairs). Multivariate phenotypic and genetic regression analyses were used to establish the predictive strength of the two motor development traits for future exercise behavior, the contribution of genetic and shared environmental factors to the variance in all traits, and the contribution of familial confounding to the phenotypic prediction. RESULTS: Significant heritability (h2) and shared environmental (c2) effects were found for early motor development in boys and girls (h2 = 43-65%; c2 = 16-48%). For exercise behavior, genetic influences increased with age (boys: h2age7 = 22% to h2age14 = 51%; girls: h2age7 = 3% to h2age14 = 18%) paired to a parallel decrease in the influence of the shared environment (boys: c2age7 = 68% to c2age14 = 19%; girls: c2age7 = 80% to c2age14 = 48%). Early motor development explained 4.3% (p < 0.001) of the variance in future exercise behavior in boys but only 1.9% (p < 0.001) in girls. If the effect in boys was due to a causal effect of motor development on exercise behavior, all of the factors influencing motor development would, through the causal chain, also influence future exercise behavior. Instead, only the genetic parts of the regression of exercise behavior on motor development were significant. Shared and unique environmental parts of the regression were largely non-significant, which is at odds with the causal hypothesis. CONCLUSION: No support was found for a direct causal effect in the association between rapid early motor development on future exercise behavior. In boys, early motor development appears to be an expression of the same genetic factors that underlie the heritability of childhood and early adolescent exercise behavior.

Genetic and Environmental Effects on the Early Motor Development as a Function of Parental Educational Attainment.

INTRODUCTION: The contribution of genetic and environmental factors to individual differences in early motor development is still largely uncharted. This large-scale twin study establishes the genetic and environmental influences on the timing of motor milestones achievement, and it further tests whether the influences are moderated by parental education. METHODS: The twins came from families registered in the Netherlands Twin Register (NTR) from 1986 to 2016. In 30,256 complete twin pairs, mother-reported ages at which each twin was able to first-time roll from back to belly, sit unassisted, hands-and-knees crawl, stand up unaided, and walk independently were used to extract an early motor development factor. Parental education was dichotomized ("both parents with low/average education" vs "at least one parent with high education" with university degree as a threshold). RESULTS: Additive genetics explained 52% of the variance in motor development, the remaining 39% and 9% were explained by shared and nonshared environment separately. Mean age of achieving motor milestones tended to be higher in infants with high educated parents, and a moderation of parental education on the genetic and environmental variance in motor development was seen in female twins with larger heritability in the high educated parents group (64% vs 43%) paired to a lower shared environmental influence (28% vs 48%). Only 7%-8% of the variance was accounted for nonshared environmental factors, including measurement error. The pattern of results did not change when the degree of urbanicity, a correlate of parental education, was additionally considered. CONCLUSIONS: Genetic factors explain most of the individual differences in the timing of motor milestone achievement, but factors related to the shared home environment also play an important role in early motor development.

The Effect of Physical Exercise on Fundamental Movement Skills and Physical Fitness among Preschool Children: Study Protocol for a Cluster-Randomized Controlled Trial.

Background: Evidence shows that physical exercise promotes preschoolers' fundamental movement skills (FMSs) and physical fitness (PF). However, studies that assess the effectiveness of different types of physical exercise interventions to improve FMSs and PF in preschool children remain scarce. To explore and compare the effectiveness of different physical exercise on FMSs and PF, interventions comprising ball games (BGs), rhythm activities (RAs), basic movements (BMs), and a combination of all related activities (multiple activities, MAs) will be conducted among preschoolers. Methods: A single-blind, five-arm, cluster-randomized trial will be conducted in kindergarten in Shanghai, China. In total, 300 healthy preschoolers, aged 4 to 5 years, will be randomized to four intervention groups (BG, RA, BM, or MA) and one control group (unorganized physical activities). Four intervention groups will receive three 30-min lessons weekly for 16 weeks. At the baseline, the end of the 16-week intervention, and the 6-month follow-up after the end of the intervention, the primary outcomes (FMSs and PF) and physical activity (PA), and sociodemographic and anthropometric data will be assessed. Discussion: This study will provide vital information regarding the effect of different physical exercise interventions on preschool children's FMSs and PF, PA, and the potential interactions between these domains. The most effective intervention strategy can be generalized to kindergarten and other preschool educational institutions in practice to promote preschoolers' development of FMSs and PF. Conclusions: This study protocol aims to provide a method to solve the problem of "how to arrange physical exercise and which kind of physical exercise program can promote FMS and PF better in preschool children".

Non-Invasive Brain Stimulation: Augmenting the Training and Performance Potential in Esports Players.

During the last two decades, esports, a highly competitive sporting activity, has gained increasing popularity. Both performance and competition in esports require players to have fine motor skills and physical and cognitive abilities in controlling and manipulating digital activities in a virtual environment. While strategies for building and improving skills and abilities are crucial for successful gaming performance, few effective training approaches exist in the fast-growing area of competitive esports. In this paper, we describe a non-invasive brain stimulation (NIBS) approach and highlight the relevance and potential areas for research while being cognizant of various technical, safety, and ethical issues related to NIBS when applied to esports.