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.

Interacting Constraints and Relative Age Effect in Elite Cross-Country Skiers and Freeskiers.

Different characteristics of sports disciplines potentially lead to skewness in birth month distribution (relative age effect, RAE). These characteristics can be considered from a constraint-based approach with interacting environmental, task, and individual constraints as a theoretical framework with which to examine variations in RAE. The main aim of the present study was to examine the theoretical predictions of the constraint-based framework by investigating the birth month distribution in cross-country skiers and freeskiers at elite junior and senior levels. The sample was comprised of top ranked Norwegian U15-U19/20 cross-country skiers and junior-level freeskiers. Birth months of top ranked international senior-level skiers in cross-country and freeskiing were also collected. Results indicated an over-representation of skiers born in the first half versus the second half of the year at all junior ages in cross-country skiing. There was no significant difference in the distribution of birth months in freeskiing or in senior cross-country skiers or freeskiers. Based upon the interacting constraint framework, the skewness towards more early-born athletes in junior cross-country skiing could be due to strict age-grouped and results-oriented developmental programs beginning at an early age (environmental constraints) as well as high-demand for physical capabilities (task constraints) that favour more physically mature athletes (individual constraints). For freeskiing, the interacting environmental (less structured and more individualistic-oriented development), task (high technical/motor skill demands), and individual (no advantage of advanced physical maturation) constraints potentially operate in the opposite direction compared to cross-country skiing.

In Pursuit of a Comprehensive Understanding of Expertise Development: A Comparison between Paths to World-Class Performance in Complex Technical vs. Endurance Demanding Sports.

A comprehensive understanding of skill acquisition is important for different performance domains, and has practical implications for both sport sciences and public health. The study compared important constraints for expertise development in a physically demanding sport (cross-country skiing) versus a technically demanding sport (freeskiing). Eighteen world-class athletes reported the importance of different constraints for their developmental history subdivided into two age spans: (1) 7-15 years and (2) 16 years until present. The total amount of training did not differ between the groups, but from the age of 16, the cross-country skiers spend approximately 98% of their training specific to their main sport, compared to 75% for freeskiers. No differences were found between the distribution of organized versus non-organized training in main sport, but freeskiers reported a higher amount of unorganized training in other sports after the age of 16. No differences were found in perceived importance of facilities, enjoyment of performing their sport, or the need for early specialization of training. After the age of 16, the cross-country skiers reported a higher need for coach involvement compared to freeskiers. The two sports mainly share common paths to expertise but differ in the need for specific training and coach involvement.

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.

A Comparison of Motives by Gender and Age Categories for Training at Norwegian Fitness Centres.

Examining participatory motives clarifies what engages and keeps individuals participating in exercise. The popularity of training at fitness centres has greatly increased over the last two decades, but individual determinants for motivation remain uncertain. This study compared motives between gender and age categories in training and performing physical activity at Norwegian fitness centres. To compare motives, a survey utilising a standardised questionnaire (MPAM-R) was conducted at six different Norwegian fitness centres. It was hypothesised that the intrinsic motive socialisation and extrinsic motive fitness would be more important among the older age categories for both genders, while the extrinsic motive appearance and intrinsic motive enjoyment would be more important among younger age groups. A total response of 183 men and 150 women, aged 14-80 years, was divided into seven categories based on their age and included in the statistical analysis. The main findings after conducting a two-way analysis of variance (ANOVA) with repeated measures, were that the most important motive for training at fitness centres was increasing fitness, followed by enjoyment, competence, vitality and appearance. The social motive was rated the lowest. Women rated fitness and enjoyment higher compared to men, and men rated the motive for appearance higher than women, but this decreased with age in both genders. With increasing age, the importance of enjoyment and competence decreased in men, while women seemed to place increased importance on vitality with age. The importance of the social motive decreased first as age increased, but then increased again in the age group 41-50 years and older. It was concluded that the motives for participating in exercise at fitness centres was dependent on individual characteristics and that motives about training at fitness centres differed by gender and changed with age.

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.

Player load in male elite soccer: Comparisons of patterns between matches and positions.

Our primary aim was to explore the development of player load throughout match time (i.e., the pattern) using moving 5-min windows in an elite soccer team and our secondary aim was to compare player load patterns between different positions within the same team. The dataset included domestic home matches (n = 34) over three seasons for a Norwegian Elite League team. Player movements (mean ± SD age 25.5 ± 4.2 years, height 183.6 ± 6.6 cm, body mass 78.9 ± 7.4 kg) were recorded at 20 Hz using body-worn sensors. Data for each variable (player load, player load per meter, total distance, accelerations, decelerations, sprint distance, high-intensity running distance) were averaged within positions in each match, converted to z-scores and averaged across all matches, yielding one time series for each variable for each position. Pattern similarity between positions was assessed with cross-correlations. Overall, we observed a distinct pattern in player load throughout match time, which also occurred in the majority of individual matches. The pattern shows peaks at regular intervals (~15 min), each followed by a period of lower load, declining until the next peak. The same pattern was evident in player load per meter. The cross-correlation analyses support the visual evidence, with correlations ranging 0.88-0.97 (p < .001) in all position pairs. In contrast, no specific patterns were discernible in total distance, accelerations, decelerations, sprint distance and high-intensity running distance, with cross-correlations ranging 0.65-0.89 (p < .001), 0.32-0.64 (p < .005), 0.18-0.65 (p < .005 in nine position pairs), 0.02-0.38 (p < .05 in three pairs) and 0.01-0.52 (p < .05 in three pairs), respectively. This study demonstrated similarity in player load patterns between both matches and positions in elite soccer competition, which could indicate a physical "pacing pattern" employed by the team.

Effect of Instructions Emphasizing Velocity or Accuracy Given in a Random or Blocked Order on Performance Testing and Kinematics in Dart Throwing.

The aims of this study were to investigate the effects of throwing instruction (i.e., velocity and accuracy) and testing order (random or blocked) on dart throwing performance testing and on the movement strategies leading to this performance. Twelve physical education students (nine men and three women, age: 24 ± 7.5; mass: 77.7 ± 15.8, height: 1.77 ± 0.06 m) performed dart throws with four different instructions, varying in priority regarding velocity and accuracy, instructed in a blocked and random manner. The main findings were that dart velocity decreased when the priority of accuracy increased. However, when accuracy was the main priority, accuracy increased only when measured for consistency. Testing order influenced peak joint kinematics of wrist flexion in addition to finger extension and the time of occurrence of elbow extension. Instructions emphasizing velocity and/or accuracy showed a clear speed-accuracy trade-off in dart throwing and thereby followed Fitts' law. Testing order had a minor effect on the speed-accuracy trade-off. The blocked testing order appeared to increase performance outcomes that favored the priority set by the instruction in contrast to the random test order. These differences were based upon adjustments of joint movements, which were based upon the knowledge of the previous attempts. These adjustments were visible between the different instructions through changes in the execution timing of peak wrist flexion and elbow and finger extension.

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.

The Validity of Functional Threshold Power and Maximal Oxygen Uptake for Cycling Performance in Moderately Trained Cyclists.

Cycling is a popular sport, and evaluation of the validity of tests to predict performance in competitions is important for athletes and coaches. Similarity between performance in sprints in mass-start bike races and in the laboratory is found, but, to our knowledge, no studies have investigated the relationship between laboratory measurements of maximal oxygen uptake (VO2max) and functional threshold power (FTP) with performance in official mass-start competitions. The purpose of this study was to evaluate the validity of a 20 min FTP test and VO2max as predictors for performance in an official mountain bike competition. Eleven moderately trained male cyclists at a local level participated in this study (age: 43 ± 5.1 years; height: 183.4 ± 5.4 m; weight: 84.4 ± 8.7 kg; body mass index: 25.1 ± 2.1). All subjects performed a 20 min FTP test in the laboratory to measure the mean power. In addition, the subjects completed an incremental test to exhaustion to determine VO2max. These two laboratory tests were analyzed together with the results from a 47 km mass-start mountain bike race, with a total elevation of 851 m. A significant relationship was found between the mean relative power (W/kg) for the 20 min FTP test and performance time in the race (r = -0.74, P < 0.01). No significant correlation was found between VO2max and cycling performance for these subjects (r = -0.37). These findings indicate that a 20 min FTP test is a more valid test for prediction of performance in mass-start bike races than a VO2max test for moderately trained cyclists.

A Population Study of Relative Age Effects on National Tests in Reading Literacy.

We examined relative age effects (RAE) in national test results in reading literacy in Norway in 2013, in Grades 5, 8, and 9 students (n = 173,421) to estimate how month of birth is associated with mean scores and different achievement levels. The results confirm that there is an approximately linear decrease in test scores across months of birth for all grades and both genders. Consequently, students born early in the year are more likely to end up at higher achievement levels than students born later in the year. Possible explanations for this phenomenon are the greater maturity of older children and that they might be considered more gifted when compared with their younger peers. Further, we found increasing gap in test scores between girls and boys from grade 5 to 8 and 9. We suggest both maturity and motivational reasons for these differences.

Dominant paradigms in motor behavior research: the motor-action controversy revisited.

In 1992, Abernethy and Sparrow published an evaluation of the historical development of the field of motor behavior research as published from 1977 up to 1988 in the Journal of Motor Behavior. The present study extends their evaluation from 1988 through 2005 using content analyses of articles on motor control and learning in this journal. Papers were categorized into the two dominant and contrasting paradigms, the motor systems approach and the action systems approach. Analysis suggests that the field of motor behavior research has changed considerably over the last three decades. The action systems approach is now the leading approach, but the motor systems approach has, however, not perished. In a Kuhnian perspective, the results might be consistent with a more long-lasting crisis, and from the available data it is not possible to predict a future outcome of the dispute between the two approaches.

The impact of physical growth and relative age effect on assessment in physical education.

Physical education (PE) is perhaps the school subject most likely to produce relative age effects (RAE). Like in sports, physical maturity gives students an advantage in PE, which might well be mistaken for superior ability. The aim of the present study is to investigate the extent to which physical growth, measured as height, and RAE reflect the assessment in Norwegian PE. Furthermore, we wanted to examine whether there is any gender differences in the assessment in PE as a function of physical growth and RAE. The participants (n = 2978) were pupils in the last three years of secondary school (13-16 years old). A custom-made questionnaire was designed to collect the necessary data. The correlations between height and mark in PE for boys in 8th, 9th, and 10th grades are respectively r = 0.14, r = 0.32, and r = 0.29. For girls, the correlations are r = 0.11, r = 0.33, and r = 0.21. All correlations are significant (p < .05). The number of pupils achieving top marks was 114 in the first half of the year, whereas it was 65 in the second half of the year. The present study showed that physical growth has an impact on the pupils' PE attainment. The physical growth is of course also mediated by the pupils' age. RAEs were found in PE attainments also in the Norwegian school system for both genders, despite all the intentions expressed in the PE curriculum.

Effect of Practicing Soccer Juggling With Different Sized Balls Upon Performance, Retention, and Transfer to Ball Reception.

The aim of this study was to investigate if making the skill acquisition phase more difficult or easier would enhance performance in soccer juggling, and if this practice has a positive intertask transfer effect to ball reception performance. Twenty-two adolescent soccer players were tested in juggling a soccer ball and in the control of an approaching ball at a pre, post and retention test. The participants were randomly divided in a small ball size and bigger ball size training group that both trained four times per week for 6 weeks. At the post and retention test both groups enhanced performance in soccer juggling test with no difference between groups and no increase in ball reception performance at these tests. It was concluded that about intra task transfer and retention of soccer juggling skills, it does not matter if you increase (small balls) or decrease the difficulty (larger balls) when using the same amount of practice time within the skill acquisition phase in soccer juggling. In addition that for ball juggling and ball reception (inter task) these two tasks differ too much in afferent information and movement characteristics that no positive transfer between these two skills no positive intertask transfer can be expected.