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Background: Physical fitness is a key aspect of children’s ability to perform activities of daily living, engage in leisure activities, and is associated with important health characteristics. As such, it shows multi-directional associations with weight status as well as executive functions, and varies according to a variety of moderating factors, such as the child’s gender, age, geographical location, and socioeconomic conditions and context. The assessment and monitoring of children’s physical fitness has gained attention in recent decades, as has the question of how to promote physical fitness through the implementation of a variety of programs and interventions. However, these programs and interventions rarely focus on children with deficits in their physical fitness. Due to their deficits, these children are at the highest risk of suffering health impairments compared to their more average fit peers. In efforts to promote physical fitness, schools could offer promising and viable approaches to interventions, as they provide access to large youth populations while providing useful infrastructure. Evidence suggests that school-based physical fitness interventions, particularly those that include supplementary physical education, are useful for promoting and improving physical fitness in children with normal fitness. However, there is little evidence on whether these interventions have similar or even greater effects on children with deficits in their physical fitness. Furthermore, the question arises whether these measures help to sustainably improve the development/trajectories of physical fitness in these children.
The present thesis aims to elucidate the following four objectives: (1) to evaluate the effects of a 14 week intervention with 2 x 45 minutes per week additional remedial physical education on physical fitness and executive function in children with deficits in their physical fitness; (2) to assess moderating effects of body height and body mass on physical fitness components in children with physical fitness deficits; (3) to assess moderating effects of age and skeletal growth on physical fitness in children with physical fitness deficits; and (4) to analyse moderating effects of different physical fitness components on executive function in children with physical fitness deficits.
Methods: Using physical fitness data from the EMOTIKON study, 76 third graders with physical fitness deficits were identified in 11 schools in Brandenburg state that met the requirements for implementing a remedial physical education intervention (i.e., employing specially trained physical education teachers). The fitness intervention was implemented in a cross-over design and schools were randomly assigned to either an intervention-control or control-intervention group. The remedial physical education intervention consisted of a 14 week, 2 x 45 minutes per week remedial physical education curriculum supplemented by a physical exercise homework program. Assessments were conducted at the beginning and end of each intervention and control period, and further assessments were conducted at the beginning and end of each school year until the end of sixth grade. Physical fitness as the primary outcome was assessed using fitness tests implemented in the EMOTIKON study (i.e., lower body muscular strength (standing long jump), speed (20 m sprint), cardiorespiratory fitness (6 min run), agility (star run), upper body muscular strength (ball push test), and balance (one leg balance)). Executive functions as a secondary outcome were assessed using attention and psychomotor processing speed (digit symbol substitution test), mental flexibility and fine motor skills (trail making test), and inhibitory control (Simon task). Anthropometric measures such as body height, body mass, maturity offset, and body composition parameters, as well as socioeconomic information were recorded as potential moderators.
Results: (1) The evaluation of possible effects of the remedial physical education intervention on physical fitness and executive functions of children with deficits in their physical fitness did not reveal any detectable intervention-related improvements in physical fitness or executive functions. The implemented analysis strategies also showed moderating effects of body mass index (BMI) on performance in 6 min run, star run, and standing long jump, with children with a lower BMI performing better, moderating effects of proximity to Berlin on performance in the 6 min run and standing long jump, better performances being found in children living closer to Berlin, and overall gendered differences in executive function test performance, with boys performing better compared to girls. (2) Analysing moderating effects of body height and body mass on physical fitness performance, better overall physical fitness performance was found for taller children. For body mass, a negative effect was found on performance in the 6 min run (linear), standing long jump (linear), and 20 m sprint (quadratic), with better performance associated with lighter children, and a positive effect of body mass on performance in the ball push test, with heavier children performing better. In addition, the analysis revealed significant interactions between body height and body mass on performance in 6 min run and 20 m sprint, with higher body mass being associated with performance improvements in larger children, while higher body mass was associated with performance declines in smaller children. In addition, the analysis revealed overall age-related improvements in physical fitness and was able to show that children with better overall physical fitness also elicit greater age-related improvements. (3) In the analysis of moderating effects of age and maturity offset on physical fitness performances, two unrotated principal components of z-transformed age and maturity offset values were calculated (i.e., relative growth = (age + maturity offset)/2; growth delay = (age - maturity offset)) to avoid colinearity. Analysing these constructs revealed positive effects of relative growth on performances in star run, 20 m sprint, and standing long jump, with children of higher relative growth performing better. For growth delay, positive effects were found on performances in 6 min run and 20 m sprint, with children having larger growth delays showing better performances. Further, the model revealed gendered differences in 6 min run and 20 m sprint performances with girls performing better than boys. (4) Analysing the effects of physical fitness tests on executive function revealed a positive effect of star run and one leg balance performance and a negative effect of 6 min run performance on reaction speed in the Simon task. However, these effects were not detectable when individual differences were accounted for. Then these effects showed overall positive effects, with better performances being associated with faster reaction speeds. In addition, the analysis revealed a positive correlation between overall reaction speed and effects of the 6 min run, suggesting that children with greater effects of 6 min run had faster overall reaction speeds. Negative correlations were found between star run effects and age effects on Simon task reaction speed, meaning that children with larger star run effects had smaller age effects, and between 6 min run effects and star run effects on Simon task reaction speed, meaning that children with larger 6 min run effects tended to have smaller star run effects on Simon task reaction speed and vice versa.
Conclusions: (1) The lack of detectable intervention-related effects could have been caused by an insufficient intervention period, by the implementation of comprehensive and thus non- specific exercises, or by both. Accordingly, longer intervention periods and/or more specific exercises may have been more beneficial and could have led to detectable improvements in physical fitness and/or executive function. However, it remains unclear whether these interventions can benefit children with deficits in physical fitness, as it is possible that their deficits are not caused by a mere lack of exercise, but rather depend on the socioeconomic conditions of the children and their families and areas. Therefore, further research is needed to assess the moderation of physical fitness in children with physical fitness deficits and, in particular, the links between children’s environment and their physical fitness trajectories. (2) Findings from this work suggest that using BMI as a composite of body height and body mass may not be able to capture the variation associated with these parameters and their interactions. In particular, because of their multidirectional associations, further research would help elucidate how BMI and its subcomponents influence physical fitness and how they vary between children with and without physical fitness deficits. (3) The assessment of growth- related changes indicated negative effects associated with the growth spurt approaching age of peak height velocity, and furthermore showed significant differences in these effects between children. Thus, these effects and possible interindividual differences should be considered in the assessment of the development of physical fitness in children. (4) Furthermore, this work has shown that the associations between physical fitness and executive functions vary between children and may be moderated by children’s socioeconomic conditions and the structure of their daily activities. Further research is needed to explore these associations using approaches that account for individual variance.
The relevance of physical fitness for children’s and adolescents’ health is indisputable and it is crucial to regularly assess and evaluate children’s and adolescents’ individual physical fitness development to detect potential negative health consequences in time. Physical fitness tests are easy-to-administer, reliable, and valid which is why they should be widely used to provide information on performance development and health status of children and adolescents. When talking about development of physical fitness, two perspectives can be distinguished. One perspective is how the physical fitness status of children and adolescents changed / developed over the past decades (i.e., secular trends). The other perspective covers the analyses how physical fitness develops with increasing age due to growth and maturation processes. Although, the development of children’s and adolescents’ physical fitness has been extensively described and analyzed in the literature, still some questions remain to be uncovered that will be addressed in the present doctoral thesis.
Previous systematic reviews and meta-analyses have examined secular trends in children’s and adolescents’ physical fitness. However, considering that those analyses are by now 15 years old and that updates are available only to limited components of physical fitness, it is time to re-analyze the literature and examine secular trends for selected components of physical fitness (i.e., cardiorespiratory endurance, muscle strength, proxies of muscle power, and speed). Fur-thermore, the available studies on children’s development of physical fitness as well as the ef-fects of moderating variables such as age and sex have been investigated within a long-term ontogenetic perspective. However, the effects of age and sex in the transition from pre-puberty to puberty in the ninth year of life using a short-term ontogenetic perspective and the effect of timing of school enrollment on children’s development of physical fitness have not been clearly identified. Therefore, the present doctoral thesis seeks to complement the knowledge of children’s and adolescents’ physical fitness development by updating secular trend analysis in selected components of physical fitness, by examining short-term ontogenetic cross-sectional developmental differences in children`s physical fitness, and by comparing physical fitness of older- and younger-than-keyage children versus keyage-children. These findings provide valuable information about children’s and adolescents’ physical fitness development to help prevent potential deficits in physical fitness as early as possible and consequently ensure a holistic development and a lifelong healthy life.
Initially, a systematic review 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 to 18 years was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement guidelines. To examine short-term ontogenetic cross-sectional developmental differences and to compare physical fitness of older- and younger-than-keyage children versus keyage-children physical fitness data of 108,295 keyage-children (i.e., aged 8.00 to 8.99 years), 2,586 younger-than-keyage children (i.e., aged 7.00 to 7.99 years), and 26,540 older-than-keyage children (i.e., aged 9.00 to 9.99 years) from the third grade were analyzed. Physical fitness was assessed through the EMOTIKON test battery measuring cardiorespiratory endurance (i.e., 6-min-run test), coordina-tion (i.e., star-run test), speed (i.e., 20-m linear sprint test), and proxies of lower (i.e., standing long jump test) and upper limbs (i.e., ball-push test) muscle power. Statistical inference was based on Linear Mixed Models.
Findings from the systematic review revealed a large initial improvement and an equally large subsequent decline between 1986 and 2010 as well as a stabilization between 2010 and 2015 in cardiorespiratory endurance, a general trend towards a small improvement in relative muscle strength from 1972 to 2015, an overall small negative quadratic trend for proxies of muscle power from 1972 to 2015, and a small-to-medium improvement in speed from 2002 to 2015. Findings from the cross-sectional studies showed that even in a single prepubertal year of life (i.e., ninth year) physical fitness performance develops linearly with increasing chronological age, boys showed better performances than girls in all physical fitness components, and the components varied in the size of sex and age effects. Furthermore, findings revealed that older-than-keyage children showed poorer performance in physical fitness compared to keyage-children, older-than-keyage girls showed better performances than older-than-keyage boys, and younger-than-keyage children outperformed keyage-children.
Due to the varying secular trends in physical fitness, it is recommended to promote initiatives for physical activity and physical fitness for children and adolescents to prevent adverse effects on health and well-being. More precisely, public health initiatives should specifically consider exercising cardiorespiratory endurance and muscle strength because both components showed strong positive associations with markers of health. Furthermore, the findings implied that physical education teachers, coaches, or researchers can utilize a proportional adjustment to individually interpret physical fitness of prepubertal school-aged children. Special attention should be given to the promotion of physical fitness of older-than-keyage children because they showed poorer performance in physical fitness than keyage-children. Therefore, it is necessary to specifically consider this group and provide additional health and fitness programs to reduce their deficits in physical fitness experienced during prior years to guarantee a holistic development.
There is ample evidence that youth resistance training (RT) is safe, joyful, and effective for different markers of performance (e.g., muscle strength, power, linear sprint speed) and health (e.g., injury prevention). Accordingly, the first aim of this narrative review is to present and discuss the relevance of muscle strength for youth physical development. The second purpose is to report evidence on the effectiveness of RT on muscular fitness (muscle strength, power, muscle endurance), on movement skill performance and injury prevention in youth. There is evidence that RT is effective in enhancing measures of muscle fitness in children and adolescents, irrespective of sex. Additionally, numerous studies indicate that RT has positive effects on fundamental movement skills (e.g., jumping, running, throwing) in youth regardless of age, maturity, training status, and sex. Further, irrespective of age, sex, and training status, regular exposure to RT (e.g., plyometric training) decreases the risk of sustaining injuries in youth. This implies that RT should be a meaningful element of youths’ exercise programming. This has been acknowledged by global (e.g., World Health Organization) and national (e.g., National Strength and Conditioning Association) health- and performance-related organizations which is why they recommended to perform RT as an integral part of weekly exercise programs to promote muscular strength, fundamental movement skills, and to resist injuries in youth.
Many children show negative emotions related to mathematics and some even develop mathematics anxiety. The present study focused on the relation between negative emotions and arithmetical performance in children with and without developmental dyscalculia (DD) using an affective priming task. Previous findings suggested that arithmetic performance is influenced if an affective prime precedes the presentation of an arithmetic problem. In children with DD specifically, responses to arithmetic operations are supposed to be facilitated by both negative and mathematics-related primes (= negative math priming effect). We investigated mathematical performance, math anxiety, and the domain-general abilities of 172 primary school children (76 with DD and 96 controls). All participants also underwent an affective priming task which consisted of the decision whether a simple arithmetic operation (addition or subtraction) that was preceded by a prime (positive/negative/neutral or mathematics-related) was true or false. Our findings did not reveal a negative math priming effect in children with DD. Furthermore, when considering accuracy levels, gender, or math anxiety, the negative math priming effect could not be replicated. However, children with DD showed more math anxiety when explicitly assessed by a specific math anxiety interview and showed lower mathematical performance compared to controls. Moreover, math anxiety was equally present in boys and girls, even in the earliest stages of schooling, and interfered negatively with performance. In conclusion, mathematics is often associated with negative emotions that can be manifested in specific math anxiety, particularly in children with DD. Importantly, present findings suggest that in the assessed age group, it is more reliable to judge math anxiety and investigate its effects on mathematical performance explicitly by adequate questionnaires than by an affective math priming task.
This thesis investigates the comprehension of the passive voice in three distinct populations. First, the comprehension of passives by adult German speakers was studied, followed by an examination of how German-speaking children comprehend the structure. Finally, bilingual Mandarin-English speakers were tested on their comprehension of the passive voice in English, which is their L2. An integral part of testing the comprehension in all three populations is the use of structural priming. In each of the three distinct parts of the research, structural priming was used for a specific reason. In the study involving adult German speakers, productive and receptive structural priming was directly compared. The goal was to see the effect the two priming modalities have on language comprehension. In the study on German-acquiring children, structural priming was an important tool in answering the question regarding the delayed acquisition of the passive voice. Finally, in the study on the bilingual population, cross-linguistic priming was used to investigate the importance of word order in the priming effect, since Mandarin and English have different word orders in passive voice sentences.
Effects of resistance training in youth athletes on muscular fitness and athletic performance
(2016)
During the stages of long-term athlete development (LTAD), resistance training (RT) is an important means for (i) stimulating athletic development, (ii) tolerating the demands of long-term training and competition, and (iii) inducing long-term health promoting effects that are robust over time and track into adulthood. However, there is a gap in the literature with regards to optimal RT methods during LTAD and how RT is linked to biological age. Thus, the aims of this scoping review were (i) to describe and discuss the effects of RT on muscular fitness and athletic performance in youth athletes, (ii) to introduce a conceptual model on how to appropriately implement different types of RT within LTAD stages, and (iii) to identify research gaps from the existing literature by deducing implications for future research. In general, RT produced small -to -moderate effects on muscular fitness and athletic performance in youth athletes with muscular strength showing the largest improvement. Free weight, complex, and plyometric training appear to be well -suited to improve muscular fitness and athletic performance. In addition, balance training appears to be an important preparatory (facilitating) training program during all stages of LTAD but particularly during the early stages. As youth athletes become more mature, specificity, and intensity of RT methods increase. This scoping review identified research gaps that are summarized in the following and that should be addressed in future studies: (i) to elucidate the influence of gender and biological age on the adaptive potential following RT in youth athletes (especially in females), (ii) to describe RT protocols in more detail (i.e., always report stress and strain based parameters), and (iii) to examine neuromuscular and tendomuscular adaptations following RT in youth athletes.
Background: Obesity is not only a highly prevalent disease but also poses a considerable burden on children and their families. Evidence is increasing that a lack of self-regulation skills may play a role in the etiology and maintenance of obesity. Our goal with this currently ongoing trial is to examine whether training that focuses on the enhancement of self-regulation skills may increase the sustainability of a complex lifestyle intervention.
Methods/Design: In a multicenter, prospective, parallel group, randomized controlled superiority trial, 226 obese children and adolescents aged 8 to 16 years will be allocated either to a newly developed computer-training program to improve their self-regulation abilities or to a placebo control group. Randomization occurs centrally and blockwise at a 1:1 allocation ratio for each center. This study is performed in pediatric inpatient rehabilitation facilities specialized in the treatment of obesity. Observer-blind assessments of outcome variables take place at four times: at the beginning of the rehabilitation (pre), at the end of the training in the rehabilitation (post), and 6 and 12 months post-rehabilitation intervention. The primary outcome is the course of BMI-SDS over 1 year after the end of the inpatient rehabilitation. Secondary endpoints are the self-regulation skills. In addition, health-related quality of life, and snack intake will be analyzed.
Discussion: The computer-based training programs might be a feasible and attractive tool to increase the sustainability of the weight loss reached during inpatient rehabilitation.
Background: Functional abdominal pain (FAP) is not only a highly prevalent disease but also poses a considerable burden on children and their families. Untreated, FAP is highly persistent until adulthood, also leading to an increased risk of psychiatric disorders. Intervention studies underscore the efficacy of cognitive behavioral treatment approaches but are limited in terms of sample size, long-term follow-up data, controls and inclusion of psychosocial outcome data.
Methods/Design: In a multicenter randomized controlled trial, 112 children aged 7 to 12 years who fulfill the Rome III criteria for FAP will be allocated to an established cognitive behavioral training program for children with FAP (n = 56) or to an active control group (focusing on age-appropriate information delivery; n = 56). Randomization occurs centrally, blockwise and is stratified by center. This study is performed in five pediatric gastroenterology outpatient departments. Observer-blind assessments of outcome variables take place four times: pre-, post-, 3- and 12-months post-treatment. Primary outcome is the course of pain intensity and frequency. Secondary endpoints are health-related quality of life, pain-related coping and cognitions, as well as selfefficacy.
Discussion: This confirmatory randomized controlled clinical trial evaluates the efficacy of a cognitive behavioral intervention for children with FAP. By applying an active control group, time and attention processes can be controlled, and long-term follow-up data over the course of one year can be explored.
Background: There is an increasing awareness of the impact of parental risk perception on the weight course of the child and the parent's readiness to engage in preventive efforts, but only less is known about factors related to the parental perception of the right time for the implementation of preventive activities. The aim of this study was to examine parental perceptions of the appropriate time to engage in child weight management strategies, and the factors associated with different weight points at which mothers recognize the need for preventive actions.
Methods: 352 mothers with children aged 2-10 years took part in the study. We assessed mothers' perceptions of the actual and preferred weight status of their child, their ability to identify overweight and knowledge of its associated health risks, as well as perceptions of the right time for action to prevent overweight in their child. A regression analysis was conducted to examine whether demographic and weight related factors as well as the maternal general risk perception were associated with recognizing the need to implement prevention strategies.
Results: Although most of the parents considered a BMI in the 75th to 90th percentile a valid reason to engage in the prevention of overweight, 19% of the mothers were not willing to engage in prevention until their child reached the 97th percentile. Whereas the child's sex and the identification of an elevated BMI were significant predictors for parents' recognition of the 75th percentile as right point to engage in prevention efforts, an inability to recognize physical health risks associated with overweight silhouettes emerged as a significant factor predicting which parents would delay prevention efforts until a child's BMI reached the 97th percentile.
Conclusion: Parental misperceptions of overweight and associated health risks constitute unfavorable conditions for preventive actions. Feedback on the health risks associated with overweight could help increase maternal readiness for change.
Due to their multifunctionality, tablets offer tremendous advantages for research on handwriting dynamics or for interactive use of learning apps in schools. Further, the widespread use of tablet computers has had a great impact on handwriting in the current generation. But, is it advisable to teach how to write and to assess handwriting in pre- and primary schoolchildren on tablets rather than on paper? Since handwriting is not automatized before the age of 10 years, children's handwriting movements require graphomotor and visual feedback as well as permanent control of movement execution during handwriting. Modifications in writing conditions, for instance the smoother writing surface of a tablet, might influence handwriting performance in general and in particular those of non-automatized beginning writers. In order to investigate how handwriting performance is affected by a difference in friction of the writing surface, we recruited three groups with varying levels of handwriting automaticity: 25 preschoolers, 27 second graders, and 25 adults. We administered three tasks measuring graphomotor abilities, visuomotor abilities, and handwriting performance (only second graders and adults). We evaluated two aspects of handwriting performance: the handwriting quality with a visual score and the handwriting dynamics using online handwriting measures [e.g., writing duration, writing velocity, strokes and number of inversions in velocity (NIV)]. In particular, NIVs which describe the number of velocity peaks during handwriting are directly related to the level of handwriting automaticity. In general, we found differences between writing on paper compared to the tablet. These differences were partly task-dependent. The comparison between tablet and paper revealed a faster writing velocity for all groups and all tasks on the tablet which indicates that all participants—even the experienced writers—were influenced by the lower friction of the tablet surface. Our results for the group-comparison show advancing levels in handwriting automaticity from preschoolers to second graders to adults, which confirms that our method depicts handwriting performance in groups with varying degrees of handwriting automaticity. We conclude that the smoother tablet surface requires additional control of handwriting movements and therefore might present an additional challenge for learners of handwriting.