Psychometric Properties of the Pictorial Scale of Perceived Movement Skill Competence for Young Norwegian Children

The objective of this study was to examine the psychometric properties of the Pictorial Scale of Perceived Movement Skill Competence (PMSC) for young Norwegian children, a scale that is aligned with skills assessed in the Test of Gross Motor Development- Third Edition. We used convenience sampling to recruit 396 Norwegian-speaking children (7-10-year-olds) who completed the PMSC. A confirmatory factor analysis (CFA) confirmed factorial validity for the proposed three-factor model of the PMSC, encompassing measures of self-perceived ball, locomotor, and active play competence. Internal item consistency coefficients of these sub-scales were acceptable, and subsequent measurement invariant analysis found a gender difference such that boys rated their competence higher than girls in running, jumping forward, hitting a ball (racket), kicking, throwing a ball and rope climbing, while girls rated themselves higher, compared to boys, in galloping and skating/blading. Furthermore, there was a slightly better model fit for boys than for girls. Several items were significantly related to children's age, and the three-factor model exhibited differential age related factor mean differences across older and younger children. Overall, we found the PMSC to have acceptable psychometric properties for confident use in assessing perceived motor competence among 7-10-year-old Norwegian children, though we observed age and gender differences in children's responses that warrant careful interpretation of results and further research investigation.

Assessment of psychometric properties and measurement invariance of the sensation seeking scale for children in a Norwegian sample

Introduction

The aim of this study was to examine the psychometric properties of a Norwegian translation of the Sensation Seeking Scale for Children (SSSC), designed for children between 7 and 12 years of age.

Methods

A sample of 393 children (7-10 years old) were recruited to participate in the study. The SSSC was administered through interviews with each child, wherein their responses to the SSSC questionnaire were recorded on a tablet.

Results

Analysis of internal consistency reliability did not show acceptable reliability for all subscales, and confirmatory factor analysis (CFA) showed that the Thrill Seeking and Behavioral Intensity subscales were associated and somewhat overlapping, while Behavioral Inhibition appeared as a single factor. A further explanatory factor analysis (EFA) revealed a two-factor solution. CFA of the two-factor solution resulted in the removal of some items in both factors due to low factor loadings. The final factors resulting from this analysis were Thrill and Intensity Seeking (13 items) and Behavioral Inhibition (7 items). The results also show that boys scored higher than girls on Thrill and Intensity Seeking while girls scored higher than boys on Behavioral Inhibition. Furthermore, age was positively associated with both subscales, meaning that older children tended to score higher.

Discussion

The results in this study suggest that measures of children's sensation seeking might be sensitive to cultural contexts and that, at least in a Norwegian population, a two-factor solution of the SSSC is recommended.

Individual differences in children's movement variability in a virtual reality playground task

Children's movements are highly complex, and thus require measurements that capture various gross motor strategies. This study examined whether aspects of individual differences in children's gross motor movement patterns could be captured in virtual reality (VR) and how motor movements could be conceptualized through freezing-freeing patterns of degrees of freedom. To this end, a three-minute VR scenario was developed for children to freely explore, play, and move around without further instructions, and their movement strategies were simultaneously captured by a non-invasive inertial motion capture system. Sixty-four children aged 7-10 (boys: n = 37, girls: n = 27) participated. The results of correlational and principal component analysis (PCA) on measures of variability of upper extremities indicated significant relationships between nearly all measures (r = 0.31-0.69, p < 0.05). Similarly, a PCA on variability from joint movements in the lower extremities indicated relatively high intercorrelations (r = 0.31-0.71, p < 0.01). A pattern of four different variability profiles was indicated in the interrelationship between the upper and lower body. These findings emphasize the value of using innovative measurements and whole-body motion capture to disentangle individual differences in children's movement variability in product- and process-oriented assessments of gross motor competence.

Psychometric properties of the Adolescent Motor Competence Questionnaire for Norwegian adolescents

The objective of this study was to examine the psychometric properties of the Adolescent Motor Competence Questionnaire (AMCQ) for Norwegian adolescents. To this end, a sample of 349 Norwegian-speaking adolescents (13-16 years old) were recruited and completed the AMCQ. Initial results showed that confirmatory factor analysis (CFA) did not indicate statistical support for previous statistical models reported in the literature. Further analysis indicated factorial validity for a novel three-factor model identified through exploratory factor analysis, encompassing measures of fine motor skill (α = 0.65), gross motor skill (α = 0.74), and activities of daily living (ADL; α = 0.79) with acceptable internal consistency coefficients. Subsequent analysis indicated indices of measurement invariance in the study sample, as males rated their competence higher compared to females in 19 of the 27 items, and better model fit was obtained for the female adolescents. Strong invariance was tenable, and no factor mean differences were found across older and younger adolescents or across BMI scores. Overall results thus suggested that the AMCQ has acceptable psychometric properties and can be confidently used in further work with perceived motor competence in Norwegian 13-16 years-old adolescents.

Distinct clusters of movement entropy in children's exploration of a virtual reality balance beam

Although assessing motor competence is vital to advancing current understandings of motor development and its significance in various fields, no consensus exists on how the construct should be operationalised and measured. Existing approaches to assessing motor competence in children typically involve applying qualitative and/or quantitative scoring procedures in which children's performance is evaluated according to certain levels of assessment-specific task performance dependent upon predefined sets of instructions and procedures. Building upon ecological dynamics as a framework, different levels of motor competence can be identified in children's attempts to coordinate their degrees of freedom while trying to complete the interactive task and environmental constraints. Given the dynamic, nonlinear features of that coordinating process, assessments need to consider the inherit structure of inter- and intra-individual variability in patterns of movement. Against that background, we investigated 7-10-year-old children's (n = 58) whole-body joint kinematics as they freely explored a balance beam in a virtual reality playground. Specifically, we used exploratory cluster analysis to examine the discriminatory capability of utilising joint-specific sample entropy as a window into individual differences in movement coordination that emerged from children's exploration of the constraints embedded in the virtual task. Among the results, three clusters of children with distinct profiles of movement variability emerged, all of which showed heterogeneous levels of repeatability in joint movements in combination with the level of spatiotemporal exploration on the balance beam that could not be explained by between-cluster differences in age and gender distributions. Those findings suggest that entropy from whole-body movements can be used to cluster children into distinct groups with different profiles regarding the structure of movement variability, which can inform new understandings and the development of gross motor competence assessments for children.

Constituent Year Effects and Performance in Alpine Skiing Junior World Championships

This study examines constituent year effect (CYE) and race performance among junior alpine skiers in the World Championships. In various junior age cohorts competing together, variation in skiing performance can be expected not only due to practice load and experience but also due to inter-individual differences in physical and psychological maturation. Within a one-year cohort, this effect has been referred to as the birth month effect or the relative age effect (RAE). In cohorts with multiple age bands, the effect is termed the constituent year effect (CYE). The CYE works in principle as the RAE but can function as a magnifying lens of the development within a larger multi-year cohort. The results of the current study indicate that CYEs are present among junior alpine skier performance in the junior World Championships. The magnitude of the constituent year effect is greater in speed events (i.e., downhill and super-G) than in technical events (i.e., slalom and giant slalom), and greater among male skiers compared to female skiers. The findings are discussed in relation to previous research on relative age effects more generally and within the sport context specifically.

Virtual Risk Management-Exploring Effects of Childhood Risk Experiences through Innovative Methods (ViRMa) for Primary School Children in Norway: Study Protocol for the ViRMa Project

BACKGROUND

Research indicates that risky play benefits children's risk assessment and risk management skills and offers several positive health effects such as resilience, social skills, physical activity, well-being, and involvement. There are also indications that the lack of risky play and autonomy increases the likelihood of anxiety. Despite its well-documented importance, and the willingness of children to engage in risky play, this type of play is increasingly restricted. Assessing long-term effects of risky play has been problematic because of ethical issues with conducting studies designed to allow or encourage children to take physical risks with the potential of injury.

OBJECTIVE

The Virtual Risk Management project aims to examine children's development of risk management skills through risky play. To accomplish this, the project aims to use and validate newly developed and ethically appropriate data collection tools such as virtual reality, eye tracking, and motion capturing, and to provide insight into how children assess and handle risk situations and how children's past risky play experiences are associated with their risk management.

METHODS

We will recruit 500 children aged 7-10 years and their parents from primary schools in Norway. Children's risk management will be measured through data concerning their risk assessment, risk willingness, and risk handling when completing a number of tasks in 3 categories of virtual reality scenarios: street crossing, river crossing, and playing on playground equipment. The children will move around physically in a large space while conducting the tasks and wear 17 motion-capturing sensors that will measure their movements to analyze motor skills. We will also collect data on children's perceived motor competence and their sensation-seeking personality. To obtain data on children's risk experiences, parents will complete questionnaires on their parental style and risk tolerance, as well as information about the child's practical risk experience.

RESULTS

Four schools have been recruited to participate in data collection. The recruitment of children and parents for this study started in December 2022, and as of April 2023, a total of 433 parents have consented for their children to participate.

CONCLUSIONS

The Virtual Risk Management project will increase our understanding of how children's characteristics, upbringing, and previous experiences influence their learning and ability to handle challenges. Through development and use of cutting-edge technology and previously developed measures to describe aspects of the children's past experiences, this project addresses crucial topics related to children's health and development. Such knowledge may guide pedagogical questions and the development of educational, injury prevention, and other health-related interventions, and reveal essential areas for focus in future studies. It may also impact how risk is addressed in crucial societal institutions such as the family, early childhood education, and schools.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/45857.

Development and Content Validation of the Swimming Competence Assessment Scale (SCAS): A Modified Delphi Study

The purpose of this study was to design and develop the Swimming Competence Assessment Scale (SCAS) to measure children's aquatic skills as they align with the physical education curriculum for Norwegian primary schools. We conducted a three-round modified Delphi study involving 22 national experts in the aquatic profession. Experts reached consensus on scale items within an observation form and coding sheet based on a swimming proficiency test for measuring six aquatic skills: water entry, frontstroke swimming, surface dive, float/rest, backstroke swimming and water exit. Independent experts obtained high agreement (scale level: 88%, item level: 80-93%) on the relevance, representativeness, and clarity of the scale. Current results suggest that the SCAS is a valid instrument for researchers and practitioners to observe and record children's aquatic proficiency for the purpose of screening and developing aquatic education.

Effects of Free Play and Partly Structured Playground Activity on Motor Competence in Preschool Children: A Pragmatic Comparison Trial

Both the indoor and the outdoor environments and their organization exert pronounced influence upon physical activity behavior and motor development of preschool children. The aim of this study was to explore whether partly structured activity or free play in a specific playground had different impacts on motor competence development in 4–6-year-old preschoolers. The study had a pretest–post-test design, with two intervention groups and one control. Sixty-two children were included in a partly structured activity group and forty-three children in a free-play group. Both groups participated in playground activities consisting of 10 sessions (once a week), each lasting 1 h, in a specific playground setting. For the partly structured activity group, activities in each session consisted of a combination of both structured and free activity while the free-play group were engaged in unstructured play only. The control group did not attend the playground activities (N = 36). To assess levels of motor skills, each child completed pre- and post-tests using the Movement Assessment Battery for children (MABC-2), the Test of Motor Competence (TMC) and two playground-specific tests. A 3 (study group) and X 2 (gender) ANCOVAs were conducted on post-test scores on each of the test items from TMC, MABC-II and playground tests, with pre-test scores as covariates. Post hoc pairwise multiple comparisons were conducted with the alpha Bonferroni corrected, and the partial eta-squared (η2p) was applied as a measure of effect size. The results indicate no significant differences in motor competence measured by the TMC or the MABC-2 between groups. On the contrary, a significant improvement in performance in the playground-specific tests was observed in the partly structured activity group compared to the free-play and control groups.

Variations in the relative age effect with age and sex, and over time-Elite-level data from international soccer world cups

The relative age effect (RAE) is a statistical bias observed across sport contexts and consists of a systematic skewness in birth date distribution within an annual-age cohort. In soccer, January 1st is the common cut-off date when categorizing players in competitions according to their chronological age, which potentially disadvantages those within the cohort who were born later in the year. Thus, relatively older soccer players in their cohort can be favored in talent identification, selection, and development. The aim of the current study was to investigate the variations in RAE in male and female international youth world-cup tournaments (U17 and U20) in the period from 1997-2019 and in international senior world-cup-tournaments from 2006-2019. A total of 20,401 soccer players participating in 47 different tournaments were analyzed. The birthdate distributions were categorized into four quartiles (January-March, Q1; April-June, Q2; July-September, Q3; October-December, Q4) and compared to a uniform distribution using Chi-square analysis with Cramer's V (Vc) as a measure of effect size. Based on the existing data concerning RAE in elite junior and senior soccer, it was hypothesized that: (I) the RAE is present in youth soccer world cup tournaments but is stronger in male players than in female players; (II) the younger the soccer players, the stronger the RAE; and (III) the RAE in world cup soccer tournaments has strengthened over time. All these hypotheses were supported by the data; novel findings included that the effect has now entered women's soccer, and in men's soccer it persists into senior world cup tournaments. Thus, a strong RAE bias occurs in selection among elite soccer players competing in international world cup tournaments.

The association between academic achievement in physical education and timing of biological maturity in adolescents

Individual differences in tempo and timing of biological maturity, especially in adolescents, has been argued as a potential underlying cause of relative age effects observed in Physical education (PE). Indeed, differences in maturation could influence pupils`achievement in PE where motor behavior and physical activity are central tenets. However, the timing of biological maturity has not previously been investigated in the context of academic achievement in PE. Therefore, the current study`s aim was to investigate the association between timing of biological maturity and relative age on adolescents`academic achievement in PE. The data material consists of two samples from lower secondary schools (13–16 years old). Sample 1 (45 boys and 31 girls) was used to compare differences in anthropometrics and indicators of biological maturity between pupils with different grades (i.e., 3/4, 5, 6), while in sample 2 (114 boys and 127 girls) differences in mean grade were compared between birth quartiles. Pupils`final grade in PE were collected for both samples as a proxy for academic achievement. A one-way analysis of variance indicated a moderate-to-large association between timing of biological maturity, through age at peak height velocity, and academic achievement in PE, where later maturing pupils received a higher grade compared to earlier maturing pupils. Results from a factorial analysis of variance indicated an interaction effect between gender and birth quartile on academic achievement in PE. Post hoc analysis revealed that relatively younger boys received significantly lower grades as opposed to their relatively older peers. This effect was not present for girls. Collectively, these results indicate that developmental differences are associated with academic achievement in PE. Hence, PE teachers should be aware of these individual constraints in their teaching and assessment practice to accommodate fair and equal opportunities for achievement in the subject.

Association Between Motor Competence, Physical Fitness, and Academic Achievement in Physical Education in 13- to 16-Year-Old School Children

In physical education (PE), both assessment practices and choice of teaching content indicate that pupil-related factors such as motor competence and physical fitness potentially influence pupils' academic achievement in PE. However, neither of these factors are explicitly expressed as assessment criteria in the Norwegian PE-curriculum. Hence, the aim of the current study was to investigate potential differences in motor competence and physical fitness between pupils with different academic achievements in PE. Forty-five boys and 31 girls (N = 76) from grades 8 to 10 in the lower secondary school participated in this study. In addition to collecting pupils' final grade in PE, as a proxy for academic achievement, they were assessed on the Test of Motor Competence (placing bricks, building bricks, heal-to-toe-walking, and walking/running in slopes) and four task items from the Test of Physical fitness (standing broad jump, pushing medicine ball, running 20 m as fast as possible, and reduced Cooper test). In the main analysis, the total score for motor competence and physical fitness, as well as their respective task items, were compared between pupils with different grades (i.e., 3 or 4, 5, 6). A one-way ANOVA revealed neither significant difference between pupils with different grades in overall motor competence (total score) nor the respective task items for fine motor assessment or the gross motor task heal-to-toe-walking. However, there was a large difference between pupils with different grades in performance of the gross motor task walking/running in slopes, where pupils receiving a grade of 6 and 5 completed the task significantly faster compared to their peers with a grade of 3 or 4. Furthermore, a one-way ANOVA indicated moderate-to-large differences between pupils with different grades in the total score of physical fitness and performance in three of the four respective task items (i.e., standing broad jump, running 20 m as fast as possible, and reduced Cooper test). Pupils with a grade of 6 had a significantly greater total score of physical fitness and jumped longer compared to pupils with a grade of 5 and 3 or 4. Additionally, pupils with a grade of 6 ran significantly faster as opposed to pupils with a grade of 3 or 4. Performance on the reduced Cooper test was significantly different between all groups of grades, with the distance covered being progressively increased from pupils receiving a grade of 3 or 4 to 6, respectively. These results indicate that physical fitness levels and one component of motor competence may influence pupils' academic achievement in PE. Since neither certain levels of gross motor competence nor physical fitness are explicitly stated as assessment criteria in the Norwegian PE curriculum, these findings may indicate a lack of alignment between PE-teachers' assessment practice and the curriculum's intentions. It is argued that PE-teachers should be aware of how these individual constraints may influence pupils' academic achievement in PE so that all pupils are given equal opportunities to meet the described learning outcomes.

Bilateral Interference in Motor Performance in Homologous vs. Non-homologous Proximal and Distal Effectors

Performance of bimanual motor actions requires coordinated and integrated bilateral communication, but in some bimanual tasks, neural interactions and crosstalk might cause bilateral interference. The level of interference probably depends on the proportions of bilateral interneurons connecting homologous areas of the motor cortex in the two hemispheres. The neuromuscular system for proximal muscles has a higher number of bilateral interneurons connecting homologous areas of the motor cortex compared to distal muscles. Based on the differences in neurophysiological organization for proximal vs. distal effectors in the upper extremities, the purpose of the present experiment was to evaluate how the level of bilateral interference depends on whether the bilateral interference task is performed with homologous or non-homologous effectors as the primary task. Fourteen participants first performed a unilateral primary motor task with the dominant arm with (1) proximal and (2) distal controlled joysticks. Performance in the unilateral condition with the dominant arm was compared to the same effector’s performance when two different bilateral interference tasks were performed simultaneously with the non-dominant arm. The two different bilateral interference tasks were subdivided into (1) homologous and (2) non-homologous effectors. The results showed a significant decrease in performance for both proximal and distal controlled joysticks, and this effect was independent of whether the bilateral interference tasks were introduced with homologous or non-homologous effectors. The overall performance decrease as a result of bilateral interference was larger for proximal compared to distal controlled joysticks. Furthermore, a proximal bilateral interference caused a larger performance decrement independent of whether the primary motor task was controlled by a proximal or distal joystick. A novel finding was that the distal joystick performance equally interfered with either homologous (distal bilateral interference) or non-homologous (proximal bilateral interference) interference tasks performed simultaneously. The results indicate that the proximal–distal distinction is an important organismic constraint on motor control and for understanding bilateral communication and interference in general and, in particular, how bilateral interference caused by homologous vs. non-homologous effectors impacts motor performance for proximal and distal effectors. The results seem to map neuroanatomical and neurophysiological differences for these effectors.

Age at Nomination Among Soccer Players Nominated for Major International Individual Awards: A Better Proxy for the Age of Peak Individual Soccer Performance?

Individual soccer performance is notoriously difficult to measure due to the many contributing sub-variables and the variety of contexts within which skills must be utilised. Furthermore, performance differs across rather specialised playing positions. In research, soccer performance is often measured using combinations of, or even single, sub-variables. All too often these variables have not been validated against actual performance. Another approach is the use of proxies. In sports research, the age of athletes when winning championship medals has been used as a proxy for determining their age of peak performance. In soccer, studies have used the average age of players in top European leagues or in the Champions League to determine the age of individual peak performance. Such approaches have methodological shortcomings and may underestimate the peak. We explore the use of a new proxy, the age at nomination for major individual awards, to determine the average age at peak individual soccer performance. A total of 1,981 players nominated for major awards from 1956 to 2019 were included, and a subset of 653 retired players was extracted, thus including players’ complete careers. Players’ average ages at nomination, at their first nomination, and at their last ever nomination were calculated, and differences across playing positions were calculated together with changes over time in the average age at peak. Based on our proxy, the age of individual peak soccer performance occurs around 27–28 years, varying across playing positions from 26 to 31 years. A player’s first peak, on average, seems to coincide with known peaks of physiological variables; their last-ever peak occurs long after physiological performance has started to decline, indicating that the decline can be compensated for by other variables. The peak age is higher than previously reported for soccer; however, it is similar to those in other team ball sports. The average age at peak performance has increased over time, especially in the last decade. Our approach of using proxies for unearthing information about hidden features of otherwise immeasurable complex performance appears to be viable, and such proxies may be used to validate sub-variables that measure complex behaviour.

More Pronounced Bimanual Interference in Proximal Compared to Distal Effectors of the Upper Extremities

Bimanual performance depends on effective and modular bilateral communication between the two bodysides. Bilateral neural interactions between the bodysides could cause bimanual interference, and the neuromuscular system for proximal and distal muscles is differently organized, where proximal muscles have more bilateral interneurons at both cortical and spinal level compared to distal muscles. These differences might increase the potential for bimanual interference between proximal arm muscles, because of greater proportions of bilateral interneurons to proximal muscles. The purpose of the present experiment was to evaluate potential differences in bimanual interference between proximal versus distal effectors in the upper extremities. 14 participants first performed a unilateral primary motor task with dominant arm with (1) a proximal and (2) distal controlled joysticks (condition A). Performance in condition A, was compared with the same effector’s performance when a bimanual interference task was performed simultaneously with the non-dominant arm (condition B). The results showed a significant bimanual interference for both the proximal and distal controlled joysticks. Most interestingly, the bimanual interference was larger for the proximal joystick compared to the distal controlled joystick. The increase in spatial accuracy error was higher for the proximal controlled joystick, compared with the distal controlled joystick. These results indicate that the proximal-distal distinction is an important organismic constraint on motor control, and especially for bilateral communication. There seem to be an undesired bilateral interference for both proximal and distal muscles. The interference is higher in the case of proximal effectors compared distal effectors, and the results seem to map the neuroanatomical and neurophysiological differences for these effectors.

Variations in the constituent year effect in Junior World Championships in alpine skiing: A window into relative development effects?

While research on the effects of 'birth month' is usually referred to as relative age effects, the study of the effects of 'birth year' is described as the constituent year effect (CYE). In the present study we examined the impact of the CYE on participation in the Junior World Championship in alpine skiing. Based on previous research, we expected to find increasing numbers of participants the older the age-group, and that the CYE would be stronger in the speed events compared to the technical ones. The sample in the present study consisted of 1188 male skiers and 859 female skiers within the age range of 17 to 21 years at the time of competition. The results show that the number of male participants increased with increasing age, which can be described as a CYE. For female skiers, a CYE was found, but it dissipated two years earlier than for male skiers. The CYE varied with event and was more pronounced the higher the speed of the event. The findings thus suggest that a constituent year effect exists among skiers participating in the FIS Junior World Ski Championship in the alpine skiing championships, and that the effect varies with gender and event, rather unrelated to age. Thus, it seems that the effect may not be a relative age effect, but instead a relative development effect.

A Golden Age for Motor Skill Learning? Learning of an Unfamiliar Motor Task in 10-Year-Olds, Young Adults, and Adults, When Starting From Similar Baselines

It is often argued within sports circles that the age span of around 6–12 years is a golden age for motor skill learning, and this period is often described as sensitive, or even critical, for learning such skills. Consequently, skill development programmes target this age span for teaching technical and coordinative skills. In the scientific literature, however, the term golden age is scarcely seen, and few studies have even attempted to test this hypothesis. When comparing motor learning between children and adults, studies have typically found little difference or differences favoring adults. Studies that have reported precocious learning within the golden age seem not to have controlled all relevant variables. Typically, the different age groups have not started from similar baselines and have tested tasks that have not been scaled according to physical differences between individuals belonging to the various groups. The present study tested 10-year-olds, 18-year-olds, and 40-year-olds on dart throwing with their non-dominant hands. They each completed 200 throws over 2 days, with 1 day in between. All participants performed at similar levels at the pre-test, and the task was scaled according to each participant’s individual size. No difference was found between the groups after practice in terms of change in absolute error, or with respect to the slopes of their learning curves. The 10-year-olds’ learning curves were more variable compared with the other groups. Thus, the present study found no evidence that the 10-year-olds belonged to a golden age for motor learning, and we would argue that previous findings of differences might well be artefacts due to lack of control of relevant variables.

Relative difference in muscle strength between patients with knee osteoarthritis and healthy controls when tested bilaterally and joint-inclusive: an exploratory cross-sectional study

Background

To improve the goal-directedness of strength exercises for patients with knee osteoarthritis (KOA), physical rehabilitation specialists need to know which muscle-groups are most substantially weakened across the kinetic chain of both lower extremities. The purpose was to improve the knowledge base for strength exercise therapy. The objective was to explore the relative differences in muscle strength in the main directions bilaterally across the hip, knee, and ankle joints between patients with light-to-moderate symptomatic and radiographic KOA and people without knee complaints.

Methods

The design was an exploratory, patient vs. healthy control, and cross-sectional study in primary/secondary care. Twenty-eight patients with mild to moderate KOA (18 females, mean age 61) and 31 matched healthy participants (16 females, mean age 55), participated. Peak strength was tested concentrically or isometrically in all main directions for the hip, knee, and ankle joints bilaterally, and compared between groups. Strength was measured by a Biodex Dynamometer or a Commander II Muscle Tester (Hand-Held Dynamometer). Effect sizes (ES) as Cohen’s d were applied to scale and rank the difference in strength measures between the groups. Adjustment for age was performed by analysis of covariance.

Results

The most substantial muscle weaknesses were found for ankle eversion and hip external and internal rotation in the involved leg in the KOA-group compared to the control-group (ES [95% CI] −0.73 [−1.26,-0.20], − 0.74 [−1.26,-0.21], −0.71 [−1.24,-0.19], respectively; p < 0.01). Additionally, smaller but still significant moderate muscle weaknesses were indicated in four joint–strength directions: the involved leg’s ankle inversion, ankle plantar flexion, and knee extension, as well as the uninvolved leg’s ankle dorsal flexion (p < 0.05). There was no significant difference for 17 of 24 tests.

Conclusions

For patients with KOA between 45 and 70 years old, these explorative findings indicate the most substantial weaknesses of the involved leg to be in ankle and hip muscles with main actions in the frontal and transverse plane in the kinetic chain of importance during gait. Slightly less substantial, they also indicate important weakness of the knee extensor muscles. Confirmatory studies are needed to further validate these exploratory findings.

Relative difference among 27 functional measures in patients with knee osteoarthritis: an exploratory cross-sectional case-control study

Background

To raise the effectiveness of interventions, clinicians should evaluate important biopsychosocial aspects of the patient’s situation. There is limited knowledge of which factors according to the International Classification of Function, Disability, and Health (ICF) are most deviant between patients with knee osteoarthritis (KOA) and healthy individuals. To assist in measures’ selection, we aimed to quantify the differences between patients with KOA and healthy controls on various measures across the ICF dimensions of body function, activity, and participation.

Methods

We performed an exploratory cross-sectional case-control study. In total, 28 patients with mild-to-moderate KOA (mean age 61 years, 64% women) referred by general physicians to a hospital’s osteoarthritis-school, and 31 healthy participants (mean age 55 years, 52% women), volunteered. We compared between-group differences on 27 physical and self-reported measures derived from treatment guidelines, trial recommendations, and trial/outcome reviews. Independent t-test, Chi-square, and Mann-Whitney U test evaluated the significance for continuous parametric, dichotomous, and ordinal data, respectively. For parametric data, effect sizes were calculated as Cohen’s d. For non-parametric data, ds were estimated by p-values and sample sizes according to statistical formulas. Finally, all ds were ranked and interpreted after Hopkins’ scale. An age-adjusted sensitivity-analysis on parametric data validated those conclusions.

Results

Very large differences between patients and controls were found on the Pain numeric rating scale¹, the Knee Injury and Osteoarthritis Scale (KOOS, all subscales)², as well as the Örebro Musculoskeletal psychosocial scale³ (P < 0.0001). Large differences were found on the Timed 10-steps-up-and-down stair climb test⁴ and Accelerometer registered vigorous-intensity physical activity in daily life⁵ (P < 0.001). Respectively, these measures clustered on ICF as follows: ¹body function, ²all three ICF-dimensions, ³body function and participation, ⁴activity, and ⁵participation.

Limitations

The limited sample excluded elderly patients with severe obesity.

Conclusions

Very large differences across all ICF dimensions were indicated for the KOOS and Örebro questionnaires together for patients aged 45–70 with KOA. Clinicians are suggested to use them as means of selecting supplementary measures with appropriate discriminative characteristics and clear links to effective therapy. Confirmative studies are needed to further validate these explorative and partly age-unadjusted conclusions.

Interpersonal and intrapersonal entrainment of self-paced tapping rate

Entrainment is a ubiquitous property not only of interacting non-linear dynamical systems but also of human movements. In the study reported here, two premises of entrainment theory were investigated in a tapping task conducted in both interpersonal (i.e. between individuals) and intrapersonal (i.e. between effectors) conditions. Hypothesis 1 was that interacting oscillatory systems should demonstrate synchronisation, which was predicted to emerge as in-phase tapping behaviour in both inter- and intrapersonal conditions. Support for Hypothesis 1 was observed in the in-phase synchronisation of tapping in both individual bimanual trials and uni-manual and bimanual tapping in dyads. By contrast, Hypothesis 2 was that the oscillatory system with the faster initial rate would decelerate, whereas the one with the slower initial rate would accelerate, as manifest in increased self-paced tapping rates amongst participants with initially slower rates and decreased rates amongst ones who initially tapped at faster rates. However, that pattern predicted in Hypothesis 2 was not observed; on the contrary, all participants increased their tapping rates in interpersonal conditions, which occurred significantly amongst participants with the lowest preferred tapping rates. Such an outcome indicates a novel aspect of synchronised movement in humans that warrants further investigation.

Monitoring Training and Match Physical Load in Junior Soccer Players: Starters versus Substitutes

The aim of this study was to investigate differences in the physical (locomotor activities) and physiological (Banister's training impulse) in-season training load between starters and substitutes in a well-trained junior soccer team. Physical performance variables from the Polar Team Pro system were collected and analyzed from a sample of junior soccer players (N = 18; age = 15.7 ± 0.5 years; stature, 177.9 ± 4.6 cm; body mass, 67.1 ± 5.5 kg). The study analyzed a total of 10 matches and 38 training sessions during the 2018 season with linear mixed models. The players from the starting line-ups demonstrated significantly higher average weekly physical load compared to the non-starters with respect to all variables: distance (total, running, high-speed running, and sprint) [F (1, 573) ≥ 66, p < 0.001, eta = 0.10], number of accelerations and sprints [F (1, 573) ≥ 66, p < 0.001, eta = 0.10], as well as Banister's training impulse (TRIMP) [F (1, 569) = 10, p < 0.001, eta = 0.02]. Evidence from this study indicates that a large amount of weekly accumulated high-speed running and sprint distances is related to match playing time. Therefore, weekly fitness-related adaptations in running at high speeds seem to favor the starters in a soccer team.

The Effect of Aerobic Exercise on Speed and Accuracy Task Components in Motor Learning

Acute exercise has an influence on human cognition, and both theoretical approaches and previous investigations suggest that the learning process can be facilitated. A distinction has been made however, between the predominately positive effects on task speed compared to both the negative and null effects on aspects of task accuracy. The aim of this study was to investigate the effect of moderate-intensity aerobic exercise conducted before each practice trial (3 × week) for a period of four weeks, on speed and accuracy components in a novel keyboard typing task. To this end, young adults (n = 26) where randomized to a non-exercise resting group (control) or an exercise group (ergometer cycling at 65% of age-predicted maximal heart rate). Immediately after exercise or resting, participants practiced keyboard typing through specialized online software for a total of 2 h across the study period. All participants improved their speed and accuracy in the keyboard typing task. At 7-day retention, no differences were found between groups. Thus, the degree of improvement on both speed and accuracy task components was not significantly different between the exercise and control group. Further studies are warranted to establish the specific relationship between aerobic exercise and task components in motor learning and retention.

The Prevalence of Left-Handedness Is Higher Among Individuals With Developmental Coordination Disorder Than in the General Population

Many medical, psychiatric and neurological conditions have been characterized by a high prevalence of left-handedness or mixed-handedness. Several studies have indicated an elevated frequency of left-handedness in children with Developmental Coordination Disorder (DCD). However, there have been few studies explicitly exploring this relationship. The assumption is that the prevalence of left-handedness in individuals with DCD is higher compared with the prevalence in the general population and resembles the prevalence described in children with other developmental disorders. Computerized searches were conducted in PubMed, PsycInfo and CINAHL databases. Thirty-eight studies were identified and included in the present review, containing handedness distributions across 1071 persons with DCD and 1,045 controls. The distribution of DCD participants across handedness-categories was proved to be significantly different from that of the control group, with 14.7 and 8.1% left-handers, respectively. The prevalence of left-handedness within the DCD-group is lower than that reported for ASD, and larger than in dyslexia. The elevated levels of left-handedness within the different developmental disorders supports the notion of an association between the different diagnoses. However, the present results are not sufficient to conclude anything about a common cause or underlying factor via the male hormone testosterone. The present results could act as a starting point for testing the hypothesis of such a common factor, as one of the requirements is an elevated prevalence of left-handedness, and without such considerable doubt would be cast upon the hypothesis.

Is it possible to change handedness after only a short period of practice? Effects of 15 days of intensive practice on left-hand writing in strong right-handers

Previous studies have argued that a person's ability to write legibly with the non-dominant hand after a limited amount of practice suggests that manual skill can be easily transferred. The present study investigated the degree to which handedness can be altered by short-term practice on the highly complex manual activity of handwriting. Nine strongly right-handed individuals practiced writing with their left hand daily for 15 consecutive days. On three occasions, at baseline, at the end of the practice period and after a one-month retention interval, the similarity of left- and right-hand writing was inspected and handedness was tested by means of the Purdue Pegboard as well as handedness questionnaires. All participants demonstrated more legible writing with their left hand after practice, and the writing was more similar to that of their preferred, right-hand writing, although to different degrees. Pegboard performance improved with the left hand, but equally as much with the right, and there were no other changes in participants' manual preference patterns. The findings of the present study do not indicate any degree of change in handedness, outside the impressive progress in left-hand writing. The large inter-individual variability, suggests that further research should focus on more individual analyses.

The Modality-Specific Learning Style Hypothesis: A Mini-Review

The impact on learning outcome of tailoring instruction and teaching toward modality-specific learning style preferences has been researched and debated for decades. Several topical reviews have concluded that there is no evidence to support the meshing hypothesis and that it represents a persistent neuromyth in education. The concept, however, is still utilized in educational practice and favored by many academics. This mini-review presents literature, which has applied explicit and rigorous methodological criteria, in relation to the meshing hypothesis. In order to demonstrate evidence for the meshing hypothesis, studies had to screen participants for their preferred learning style, assign participants to matched or non-matched conditions, and then provide the same test to assess learning for all participants, as well as presenting statistical crossover-interaction effects. Across studies that have applied these methodological criteria, the overall effect sizes were very low and non-significant, indicating that there is still no replicable statistical evidence for enhanced learning outcome by aligning instruction to modality-specific learning styles.

An Inverse Relative Age Effect in Male Alpine Skiers at the Absolute Top Level

The Relative Age Effect (RAE) can be described as the advantage of being born early after a certain cut-off date within a group of selection. The effect has been found across a wide range of sports and is particularly evident in pre-elite sports and team sports with a high selection pressure. At the absolute top level in team elite sports, the advantage of being relatively older has been reported to disappear, and even reverse, so that the relatively younger athletes are advantaged. In order to further examine such a reversal of the RAE, we investigated the performance of the overall top 50 skiers each year in the alpine World Cup, over a period of 20 years, among men (N = 234) and women (N = 235). The data indicated that the relatively younger male athletes at the absolute top level had accumulated, on average, more World Cup points compared to the relatively older skiers. No such effect was observed among the female skiers. This finding suggest the existence of a reversed relative age effect in male elite alpine skiing.

When Is a Test Score Fair for the Individual Who Is Being Tested? Effects of Different Scoring Procedures across Multiple Attempts When Testing a Motor Skill Task

Tests or test batteries used for assessing motor skills, either in research studies or in clinical settings, apply a variety of procedures for scoring performances, including everything from one to ten attempts, of which the best is scored or an average is computed. The rationale behind scoring procedures is rarely stated, and it seems that the number of attempts allowed is decided without much qualification from research. It is uncertain whether procedures fairly capture an individual's skill level. Thus, the validity of the tests may be compromised. The present study tested 24 young female soccer players on the juggling of a soccer ball. They were given 10 attempts, and trials were scored according to nine different procedures including the 'best of' or 'mean of' either one, two, three, five, or ten attempts. Individual raw scores differed widely across trials, but no general effect of trials was found. The mean (SD) percentage difference between the lowest and highest scores was 27.7(9.9)%, with 17 players (71%) demonstrating a significant change from lowest to highest score. Correlations between raw scores were low across trials, while they were generally higher across scoring procedures. The first trial was significantly different from the remaining both as a raw score and as scoring procedure. The mean percentage difference between best-of-two and best-of-ten scores was 95%, with 50 % of the players demonstrating a significant difference between the two scoring procedures. No significant differences were found across mean-of-rule scorings. Best-of-rule and mean-of-rule scorings were significantly different except for the best-of-two vs. mean-of-two. The mean difference between highest and lowest rank across players was 6.7 (3.6), with individual rankings within the group varying 33% on average across procedures. One player moved from 3rd to 23rd place because of procedural differences. Therefore, it is concluded that scoring procedures affect results and may have an impact on test outcomes. This may present consequences for decision-making from test results, such as diagnosing and selection of intervention groups. We hope that our results would inspire further research into the scoring procedures of the vast amount of tests and tasks in common use.

A Comparison of Players' and Coaches' Perceptions of the Coach-Created Motivational Climate within Youth Soccer Teams

The coach-created motivational climate within youth sports teams has been shown to be of great importance for the quality of youths' sports experiences as well as their motivation for continuing or discontinuing sport participation. While the player's perspective on motivational climates has been studied extensively, the coach's perspective has received considerably less attention. Thus, little is known about the concordance of perceptions of the motivational climate between coaches and their players, or the lack thereof. The purpose of the present study was to directly compare players' and coaches' perceptions of the motivational climate within their respective teams. To this end, 256 male and female soccer players (15-17 years of age) from 17 different teams and their coaches (n = 29) responded to the Perceived Motivational Climate in Sports Questionnaire-2 (PMCSQ-2). The study design included responses from both coaches and players to the same questionnaire, and both groups were aware of the other part's participation. Statistical analyses revealed significant differences between players' and coaches' perceptions of the motivational climate. Specifically, players of both sexes perceived the motivational climate to be significantly more performance-oriented and significantly less mastery-oriented compared with the coaches. These findings may advance our understanding of the coach-athlete relationship, and may be of importance for understanding players' motivation for persistence or discontinuation of the sport.

A SYSTEMATIC REVIEW AND META-ANALYSIS OF DROPOUT RATES IN YOUTH SOCCER

Despite the many benefits of involvement in youth sports, participation in them declines throughout childhood and adolescence. The present study performed a systematic review and meta-analysis of 12 studies reporting dropout rates in youth soccer, involving a total of 724,036 youths ages 10-18 years from five countries. The mixed effects meta-regression analyses took into account age and sex as statistical moderators of dropout rate. Potential articles were identified through computerized searches of the databases PubMed, MedLine, Embase, and SportDiscus up until August 2014, without any further time limit. Based on results reported in the 10 included articles, the annual weighted mean dropout rate is 23.9% across the included cohorts. Meta-regression indicated that annual dropout rates are stable from the ages of 10-19 years, with higher rates for girls (26.8%) compared to boys (21.4%). The present study suggests that youth soccer players are prone to dropout rates in which close to one-fourth of players leave the sport annually, which appears to be a consistent finding across ages 10-18 years.

Evidence for a general stiffening motor control pattern in neck pain: a cross sectional study

BACKGROUND

Neck pain is associated with several alterations in neck motion and motor control. Previous studies have investigated single constructs of neck motor control, while few have applied a comprehensive set of tests to investigate cervical motor control. This comparative cross- sectional study aimed to investigate different motor control constructs in neck pain patients and healthy controls.

METHODS

A total of 166 subjects participated in the study, 91 healthy controls (HC) and 75 neck pain patients (NP) with long-lasting moderate to severe neck pain. Neck flexibility, proprioception, head steadiness, trajectory movement control, and postural sway were assessed using a 3D motion tracking system (Liberty). The different constructs of neck motion and motor control were based on tests used in previous studies.

RESULTS

Neck flexibility was lower in NP compared to HC, indicated by reduced cervical ROM and conjunct motion. Movement velocity was slower in NP compared to HC. Tests of head steadiness showed a stiffer movement pattern in NP compared to HC, indicated by lower head angular velocity. NP patients departed less from a predictable trajectory movement pattern (figure of eight) compared to healthy controls, but there was no difference for unpredictable movement patterns (the Fly test). No differences were found for postural sway in standing with eyes open and eyes closed. However, NP patients had significantly larger postural sway when standing on a balance pad. Proprioception did not differ between the groups. Largest effect sizes (ES) were found for neck flexibility (ES range: 0.2-0.8) and head steadiness (ES range: 1.3-2.0). Neck flexibility was the only construct that showed a significant association with current neck pain, while peak velocity was the only variable that showed a significant association with kinesiophobia.

CONCLUSIONS

NP patients showed an overall stiffer and more rigid neck motor control pattern compared to HC, indicated by lower neck flexibility, slower movement velocity, increased head steadiness and more rigid trajectory head motion patterns. Only neck flexibility showed a significant association with clinical features in NP patients.

Measuring soccer technique with easy-to-administer field tasks in female soccer players from four different competitive levels

Soccer is a multidimensional sport that requires skills in many different domains. Reports from competitions at the highest levels around the world suggest that a particularly decisive performance factor is a team's technical execution. Testing of technical skills in soccer has been infrequent compared with testing of physiological variables, and there has been a lack of consensus as to which tasks should be included in test batteries. In this study, the validity of four field tasks (heading, long pass, juggling, and hit-the-post) was examined by testing 108 female soccer players from four different competitive levels, representing a hierarchy of skill levels. Correlation analysis indicated that the tasks' results appeared statistically unrelated (Spearman's ρ ≤ .36). Statistical comparisons across competitive levels showed that task performance was closely correlated with players' competition level, with regression analysis indicating that 92% of the variance in mean rankings across tasks could be explained by competitive level. As the easily administered and low-cost tasks identified differences in technical skills across competitive levels, such tasks appear valid for inclusion in tests of technical skills.

Exploring individual differences in children's mathematical skills: a correlational and dimensional approach

Individual differences in mathematical skills are typically explained by an innate capability to solve mathematical tasks. At the behavioural level this implies a consistent level of mathematical achievement that can be captured by strong relationships between tasks, as well as by a single statistical dimension that underlies performance on all mathematical tasks. To investigate this general assumption, the present study explored interrelations and dimensions of mathematical skills. For this purpose, 68 ten-year-old children from two schools were tested using nine mathematics tasks from the Basic Knowledge in Mathematics Test. Relatively low-to-moderate correlations between the mathematics tasks indicated most tasks shared less than 25% of their variance. There were four principal components, accounting for 70% of the variance in mathematical skill across tasks and participants. The high specificity in mathematical skills was discussed in relation to the principle of task specificity of learning.

Interrelations between Three Fine Motor Skills in Young Adults

Motor skills are typically considered to be highly specific, although some researchers have attempted to identify evidence for general motor aptitude. The present study tested these contentions by assessing the extent of relationship between fine motor tasks, using correlations between selected performance measures for three fine motor skills. University students ages 18 to 35 years ( N = 305; 147 men, 158 women) completed three fine motor tasks with both right and left hands (placing pegs, posting coins, and placing bricks). Performance was assessed by time to complete each individual task. The intercorrelations between the three tasks were generally low and at a level that can be expected by chance ( r ≤ .3), indicating that performance was quite specific to the individual skills rather than attributable to a general ability. As a further test for evidence for a general motor ability, the dimensionality of the data set was analyzed using a principal component analysis on the correlation matrix. A three-factor solution explaining ~ 80% of the total variance in performance on the fine motor tasks was identified, where each factor could be associated with each fine motor task. These findings provide further support for the high specificity in fine motor skills and against the existence of a general aptitude for motor ability.

Timing continuous or discontinuous movements across effectors specified by different pacing modalities and intervals

Sensorimotor synchronization is hypothesized to arise through two different processes, associated with continuous or discontinuous rhythmic movements. This study investigated synchronization of continuous and discontinuous movements to different pacing signals (auditory or visual), pacing interval (500, 650, 800, 950 ms) and across effectors (non-dominant vs. non-dominant hand). The results showed that mean and variability of asynchronization errors were consistently smaller for discontinuous movements compared to continuous movements. Furthermore, both movement types were timed more accurately with auditory pacing compared to visual pacing and were more accurate with the dominant hand. Shortening the pacing interval also improved sensorimotor synchronization accuracy in both continuous and discontinuous movements. These results show the dependency of temporal control of movements on the nature of the motor task, the type and rate of extrinsic sensory information as well as the efficiency of the motor actuators for sensory integration.