The effect of bio-banding on the anthropometric, physical fitness and functional movement characteristics of academy soccer players

The study examined if maturity status bio-banding reduces within-group variance in anthropometric, physical fitness and functional movement characteristics of 319, under-14 and under-15 players from 19 UK professional soccer academies. Bio-banding reduced the within-bio-banded group variance for anthropometric values, when compared to an aggregated chronological banded group (chronological: 5.1-16.7%CV; bio-banded: 3.0-17.3%CV). Differences between these bio-banded groups ranged from moderate to very large (ES = 0.97 to 2.88). Physical performance variance (chronological: 4.8-24.9%CV; bio-banded: 3.8-26.5%CV) was also reduced with bio-banding compared to chronological aged grouping. However, not to the same extent as anthropometric values with only 68.3% of values reduced across banding methods compared to 92.6% for anthropometric data. Differences between the bio-banded groups physical qualities ranged from trivial to very large (ES = 0.00 to 3.00). The number of functional movement metrics and %CV reduced by bio-banding was lowest within the 'circa-PHV' groups (11.1-44.4%). The proportion of players achieving the threshold value score of ≥ 14 for the FMS™ was highest within the 'post-PHV' group (50.0-53.7%). The use of maturity status bio-banding can create more homogenous groups which may encourage greater competitive equity. However, findings here support a bio-banding maturity effect hypothesis, whereby maturity status bio-banding has a heightened effect on controlling for characteristics which have a stronger association to biological growth.

A comparison of multidimensional qualities discriminant of selection in elite adolescent Australian basketball athletes

Purpose

The aims of this study were to (1) quantify the multidimensional attributes of male and female basketball athletes under 16 years of age (U16) and under 18 years of age (U18), and (2) identify attributes that distinguish selection into a talent pathway according to sex and age group.

Methods

67 male and 71 female athletes competing in U16 and U18 selection trials for a state based Australian basketball talent pathway completed a multidimensional testing battery. The test battery consisted of anthropometric, physical (20- linear sprint, countermovement jump height, Yo-Yo Intermittent Recovery Test Level 2), technical (Basketball Jump Shooting Accuracy Test), tactical (video decision making), and psychological (Sports Orientation Questionnaire, Psychological Performance Inventory-Alternative) assessments. Mean differences and independent t-tests were used to assess comparative differences between selected and non-selected athletes within each age and sex cohort. Stepwise discriminant analyses were used to identify attributes that were the strongest discriminators of selection in each group (male U16, male U18, female U16, and female U18).

Results

The discrimminant models showed for male U16 athletes smaller height (ES = -0.18) and greater shooting accuracy (ES = 0.52) was most discriminant of selection. Results were largely homogenous for male U18 athletes with lower visualisation score (ES = -0.62) most discriminant of selection. In female cohorts, faster 20-m sprint time (ES = -0.66) and taller height (ES = 0.58) was most discriminant of selection in U16 athletes while greater shooting accuracy (ES = 0.67), countermovement jump height (ES = 1.04), and height (ES = 0.65) was most discriminant of selection in U18 athletes.

Conclusions

These results emphasise the differing selection priorities within adolescent basketball cohorts according to sex and age group. The testing of anthropometric, physical and technical attributes may hold particular utility in adolescent female basketball given their identified importance to selection across U16 and U18 cohorts.

Eating disorder diagnosis and the female athlete: A longitudinal analysis from college sport to retirement

OBJECTIVES

Female athletes experience eating disorders (EDs) at clinical, and subclinical, levels; most studies have determined point-prevalence rates through cross-sectional methodologies. To date, few studies have examined the long-term stability of EDs in female athletes; none extend into retirement.

DESIGN

A longitudinal investigation of ED classification (i.e., Clinical ED, Subclinical ED, Healthy) and weight control behaviors (e.g., vomiting, laxative use) from when athletes actively competed (T1) into their retirement (T2).

METHODS

Participants included U.S. female athletes (N=193) who were collegiate competitors (T1) and eventually were retired from their collegiate sports six years later (T2).

RESULTS

At T2, athletes were classified as Healthy (69.9%), Subclinical ED (26.9%), and Clinical ED (3.1%). Overall percentage of Subclinical EDs increased from 18.7% (T1) to 26.9% (T2); 52.8% of T1 Subclinical ED athletes continued to meet criteria for either Subclinical or Clinical ED at T2. Of the 13 Clinical ED athletes at T1, six (46.2%) continued to meet criteria for either a subclinical or clinical ED at T2. Though exercising (2+ hours/day; n=8, 4.1%) and dieting/fasting (4+ times/year; n=14, 7.3%) were the most frequently used weight control behaviors at T2, rates were substantially lower than at T1.

CONCLUSIONS

Retirement does not result in immediate remittance of eating concerns among female athletes; many continue or develop Subclinical and Clinical ED symptoms. Thus, addressing healthy body image and nutrition when athletes are competing is imperative to assist prevention and intervention efforts that may alleviate ED symptoms as athletes transition from sport.

A person-centered approach to achievement goal orientations in competitive tennis players: Associations with motivation and mental toughness

BACKGROUND

Research on achievement goal orientations in sport has typically relied on the use of variable-centered approaches that tend to overlook population heterogeneity. In this study, we used a person-centered approach to identify subgroups of competitive tennis players according to unique combinations of achievement goal orientations and tested for subgroup differences in motivation and mental toughness.

METHODS

A sample of 323 competitive tennis athletes (69.35% male) between 15 and 25 years of age (17.60 ± 2.40 years, mean ± SD) completed the 3 × 2 Achievement Goal Questionnaire for Sport, Sport Motivation Scale II, and Mental Toughness Index. Latent profile analysis was used to identify unique combinations of achievement goal orientations. Comparisons between latent subgroups on autonomous motivation, controlled motivation, and mental toughness were performed using analysis of variance.

RESULTS

Latent profile analysis supported 3 distinct patterns of achievement goal profiles that were primarily distinguishable based on valence of competence (i.e., approach vs. avoidance). Analyses of variance indicated that athletes who were classified into subgroups that endorsed approach types of goals (regardless of the types of avoidance goals they endorsed) reported higher levels of autonomous motivation and mental toughness.

CONCLUSION

Results indicated that athletes tend to pursue a number of achievement goals collectively rather than in isolation. Although approach goals are more commonly linked to adaptive psychological functioning and positive outcomes, avoidance goals may also be associated with desirable psychological characteristics if they are pursued in conjunction with approach types of achievement goals.

Physical function characteristics in Japanese high school volleyball players with low back pain: A case-controlled study

Low back pain (LBP) is a typical symptom in volleyball players, yet associated physical function factors have not been identified. This study purpose is to determine the relationship between LBP and physical function factors in order to identify potential factors for the management of LBP.Participants were 123 male and female volleyball players of 15- to 17-year-olds who, completed a questionnaire regarding demographic details, presence of LBP, and years of volleyball experience. Participants were divided into 2 groups based on the presence of current LBP and evaluated on physical function tests. The results of the questionnaire response and physical function test were compared between the 2 groups. Data were analyzed using a multivariate logistic regression analysis with presence and absence of current LBP as the explanatory variable.11.4% of all participants reported current LBP. Physical function factors associated with current LBP were a positive modified Thomas test, years of volleyball experience and reduced range of motion of shoulder horizontal abduction on the dominant hand side.The associations between physical function factors and LBP found in this survey suggest that attention should be given to more experienced players with decreased flexibility of hip and shoulder flexors on the dominant side in order to manage LBP in high school volleyball players.

Subcutaneous Adipose Tissue in Female Volleyball Players: Is It Related with Performance Indices?

Background and objectives: The aim of the present study was to examine subcutaneous adipose tissue distribution in female volleyball players with regards to (a) variation by anatomical site, (b) differences among age groups and playing positions, and (c) physiological characteristics associated with performance. Materials and Methods: Participants were adolescent (n = 89, age 15.6 ± 0.9 years, mean ± standard deviation) and adult female volleyball players (n = 78, 24.8 ± 5.3 years), who performed a series of anthropometric and performance tests including skinfold thickness in 10 sites, Abalakov jump (AJ) and handgrip test (HG). Results: Chin had the smallest thickness, and iliac crest and abdomen the largest. The largest correlations of skinfold thickness were shown with regards to AJ ad HG. Coefficient of variations in skinfold thickness correlated with performance indices with small magnitude. Triceps and chin were the most frequent predictors of performance indices. The anatomical site of skinfold was near the active muscle groups related to performance in HG. Conclusions: In conclusion, performance indices such AJ and HG were related with thickness of specific skinfolds and with the variation of thickness by anatomical site (i.e., the less the variation, the better the performance). Considering the relevance of specific skinfolds (e.g., triceps and chin) for performance, their further use would be recommended for purposes of training monitoring, volleyball players’ selection and talent identification.

Relative age effects in Elite Chinese soccer players: Implications of the 'one-child' policy

The relative age effect (RAE) refers to the asymmetrical distribution of birthdates in a cohort found in many achievement domains, particularly in sports with many participants like soccer. Given the uniqueness of the one-child policy in China, this study examined the existence of the RAE in elite Chinese male and female soccer players generally and relative to their playing position on the field. Results showed a clear and obvious RAE for all age groups (U20 male, U18 male, adult female and U18 female) with the observed birthdate distributions for each age group significantly different from expected distributions (p<0.05). Additionally, we noticed a differential RAE according to the players’ position on the field as reflected in different effect sizes. In male players, the RAE was significantly greater in Defenders (DF) and Goalkeepers (GK) compared to Midfielders (MF) and Forwards (FW) (V_DF = 0.266>V_GK = 0.215>V_MF = 0.178>V_FW = 0.175). In female players, GKs had a larger RAE (V_GK = 0.184>0.17, V_DF = 0.143, V_MF = 0.127, V_FW = 0.116). To reduce the negative consequences associated with RAEs throughout player development systems, potential solutions are discussed.

Selection and promotion processes are not associated by the relative age effect in an elite Spanish soccer academy

The aim of this study was to analyze the influence of the relative age effect (RAE) on the selection and promotion processes in an elite soccer academy. One hundred and eleven elite youth players who belonged to an elite soccer club from the Spanish "La Liga" participated in this study. Players were classified into three age-categories: under 14 years (U14), under 16 years (U16) and under 18 years (U18); and they were also classified in quartiles based on their date of birth (i.e., January-March, Q1; April-June, Q2; July-September, Q3; October-December, Q4). In addition, two further classification criteria were established based on the selection (i.e., selected and non-selected players) and promotion (i.e., promoted and non-promoted players) processes. The main results showed that in U14 and U16 age-categories, players born early in the year were over-represented compared to players born late in the year, although birth-distribution was not associated with the likelihood of a player to be selected or promoted. In addition, less fat in sum skinfolds, less percentage of fat, higher percentage of muscle and lower endomorphy and mesomorphy components were showed in U14 selected players, in comparison with non-selected players. Likewise, better sprint performance was found in U16 selected players versus non-selected ones. However, no significant differences on anthropometry, body composition, somatotype and physical performance were found between promoted and non-promoted players. Therefore, our results suggest there is need for coaches to reorient their talent identification programs in order to make sure that players selected to continue playing in the club have the potential to promote to the excellence in soccer.

Defining Athletes and Exercisers

Current definitions of an athlete range from loosely defined to overly restrictive, rely on qualitative subjective descriptors, and fail to capture the majority of physically active patients. To improve the understanding between exercise and health metrics a more standardized and granular classification of exercising patients is required. We propose a simplified algorithm to categorize and define exercising patients based on the: (1) intent of exercise, (2) volume of exercise (hours/week), and (3) level of competition. Further classification of physically active patients can be derived based on the intensity and volume of activity using metabolic equivalent-hours per week. In conclusion, a formal framework to classify athletes and quantify both the volume and intensity of exercise will enable more precise and meaningful associations between exercise and health outcomes.

Dynamic postural stability, is associated with competitive level, in youth league soccer players

OBJECTIVES

To assess the effect of competitive level on dynamic postural stability in young elite and sub-elite soccer players.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PARTICIPANTS

Fifty-four male soccer players of Under 16 and Under 17 categories (mean age 15.9 ± 0.6), divided into two groups who regularly compete at national (n = 28) and regional (n = 26) levels.

MAIN OUTCOME MEASURES

Dynamic Postural Stability Index (DPSI) and vertical Time to Stabilization (vTTS) for a forward-jump landing. Static postural sway was calculated on the basis of center-of-pressure trajectories for a 20 s one-legged stance.

RESULTS

Players at national level exhibit better dynamic postural control than those at regional level, as indicated by the significantly lower DPSI (0.327 vs. 0.373, p < 0.001) and vTTS (0.887 vs. 1.158 s, p = 0.003). In contrast, no differences between groups were found in any of the postural sway parameters for the static test.

CONCLUSIONS

Young soccer players at national level are characterized by better balance performance in terms of faster and more efficient stabilization after a forward jump, while one-leg static standing tests appear not challenging enough to reveal differences in balance abilities associated with the combination of superior technical and physical features.

Patellar tendon properties distinguish elite from non-elite soccer players and are related to peak horizontal but not vertical power

PURPOSE

To investigate potential differences in patellar tendon properties between elite and non-elite soccer players, and to establish whether tendon properties were related to power assessed during unilateral jumps performed in different directions.

METHODS

Elite (n = 16; age 18.1 ± 1.0 years) and non-elite (n = 13; age 22.3 ± 2.7 years) soccer players performed vertical, horizontal-forward and medial unilateral countermovement jumps (CMJs) on a force plate. Patellar tendon (PT) cross-sectional area, elongation, strain, stiffness, and Young's modulus (measured at the highest common force interval) were assessed with ultrasonography and isokinetic dynamometry.

RESULTS

Elite demonstrated greater PT elongation (6.83 ± 1.87 vs. 4.92 ± 1.88 mm, P = 0.011) and strain (11.73 ± 3.25 vs. 8.38 ± 3.06%, P = 0.009) than non-elite soccer players. Projectile range and peak horizontal power during horizontal-forward CMJ correlated positively with tendon elongation (r = 0.657 and 0.693, P < 0.001) but inversely with Young's modulus (r = - 0.376 and - 0.402; P = 0.044 and 0.031). Peak medial power during medial CMJ correlated positively with tendon elongation (r = 0.658, P < 0.001) but inversely with tendon stiffness (r = - 0.368, P = 0.050).

CONCLUSIONS

Not only does a more compliant patellar tendon appear to be an indicator of elite soccer playing status but it may also facilitate unilateral horizontal-forward and medial, but not vertical CMJ performance. These findings should be considered when prescribing talent selection and development protocols related to direction-specific power in elite soccer players.

The relative age effect is larger in Italian soccer top-level youth categories and smaller in Serie A

The relative age effect (RAE; i.e., an asymmetry in the birth distribution) is a bias observed in sport competitions that may favour relatively older athletes in talent identification. Therefore, the aim of this study was to investigate the presence of RAE in elite soccer players competing in the Italian championships, even considering the discriminations of younger and older Serie A players (in relation to the median age of the sample), and different positional roles (i.e., goalkeeper, defender, midfielder, forward) for each observed category. A total of 2051 players competing into the 2017–2018 Italian under-15 (n = 265), under-16 (n = 362), under-17 (n = 403), Primavera (n = 421) and Serie A (n = 600) championships were analysed. The birth-date distributions, grouped in four quartiles (i.e., January-March, Q1; April-June, Q2; July-September, Q3; October-December, Q4), were compared to a uniform distribution using Chi-squared analysis. The week of birth was analysed using Poisson regression. The results showed a large over-representation of players born in Q1 in all soccer player categories. However, the effect size of this trend resulted smaller as age increased. Individuals born in Q1 have about two-folds more chances to become a Serie A player compared to those born in Q4. The Poisson regression analysis showed that RAE was greater for defenders than for forwards among all categories. Therefore, a strongly biased selection emerged among elite soccer players competing in Italian championships, highlighting how young individuals born in the first three months have many more chances to become elite players compared to the others.

The isokinetic strength profile of elite soccer players according to playing position

The aim of this study was to compare isokinetic strength performance profiles in elite soccer players across different field positions. A total of 111 elite international players of Polish Ekstraklasa (the top division in Poland) were examined during the 2010–2015 seasons. The players were classified into six positional roles: central defenders (CD), external defenders (ED), central midfielders (CM), external midfielders (EM), forwards (F), and goalkeepers (G). The concentric isokinetic strength (peak torque [PT] of quadriceps and hamstrings, H/Q ratios) was calculated for the dominant leg and the non-dominant leg at angular velocity of 1.05 rad ·s^–1, whereas to assess isokinetic muscle endurance, the total work [TW] at angular velocity of 4.19 rad ·s^–1, was taken into consideration. The results showed that isokinetic strength performance varies significantly among players in different playing positions. The analysis of PT for quadriceps (PT-Q) and hamstrings (PT-H) generally showed that the goalkeepers and central midfielders had lower strength levels compared to other playing positions. In the case of PT-H and hamstring/quadricep (H/Q) peak torque ratios, statistically significant differences were also noted for the legs, where mean values noted for the dominant leg were higher than for the non-dominant leg. For TW for quadriceps (TW-Q) and hamstrings (TW-H), statistically significant differences were noted only between playing positions. TW-Q values for goalkeepers were lower than for central defenders and external midfielders. TW-H values for goalkeepers were lower than for central midfielders, central defenders and external midfielders. This study showed that specific functional activity of players in individual positions on the field influences the varied profile of isokinetic strength performance.

Kinematic analysis of the wheelchair tennis serve: Implications for classification

The aim of the present study was to assess the validity of the classification system used in Open-class wheelchair tennis by investigating the relationship between post-impact ball velocity in the serve (measured using a sports radar gun) and the severity of impairment. Shoulder and wrist angles at the instant of ball impact were also estimated from 2D motion analysis. Forty-three nationally ranked Italian Open-class wheelchair tennis players were assigned to four groups (A–D) according to descending level of activity limitation. Ten successful flat serves (WFSs) and 10 successful kick serves (WKSs) for each player were recorded. One-way ANOVA showed that the severity of impairment significantly (P < 0.05) affected post-impact ball velocity and shoulder angle at the instant of ball impact. Furthermore, the mean value of post-impact ball velocity in WFS increased from group A to group D, i.e., with descending level of activity limitation. The results of this cross-sectional study indicate that the severity of impairment per se is associated with velocity of the wheelchair tennis serve, suggesting that the current classification is flawed in that it overlooks the impact of severity of impairment on players' performance.

[Morphological and functional features of circulatory system in retired and active elite athletes]

Regular physical activity over a long period of time increases the output of the cardiovascular system. That leads to development of a normal (physiological) athlete's heart. Bradycardia, cardiac hypertrophy, and arterial hypotension are three major characteristics of a normal athlete's heart. Changes in parameters of cardiovascular system and features of heart remodeling are determined by type, frequency, and duration of a physical activity. Excessive levels of physical activity could result in development of a pathologic athlete's heart, negatively affect hearts metabolism, and increase the risk of both atherosclerosis and myocardial infarction. Autopsy studies have shown that atherosclerosis, which leads to development of an ischemic heart disease, is often found in both young and elderly athletes. 56% of sudden deaths in all athletes were due to cardiovascular problems. Reports of ischemic heart disease in athletes of all ages have increased over the past few years. Echocardiographic features and clinical outcomes of stable angina and myocardial infarction in retired professional athletes are not well studied. Further studies are needed to improve diagnosis, prevention, treatment, and rehabilitation in elite athletes with ischemic heart disease.

Novel strength test battery to permit evidence-based paralympic classification

Ordinal-scale strength assessment methods currently used in Paralympic athletics classification prevent the development of evidence-based classification systems. This study evaluated a battery of 7, ratio-scale, isometric tests with the aim of facilitating the development of evidence-based methods of classification. This study aimed to report sex-specific normal performance ranges, evaluate test-retest reliability, and evaluate the relationship between the measures and body mass.Body mass and strength measures were obtained from 118 participants-63 males and 55 females-ages 23.2 years ± 3.7 (mean ± SD). Seventeen participants completed the battery twice to evaluate test-retest reliability. The body mass-strength relationship was evaluated using Pearson correlations and allometric exponents.Conventional patterns of force production were observed. Reliability was acceptable (mean intraclass correlation = 0.85). Eight measures had moderate significant correlations with body size (r = 0.30-61). Allometric exponents were higher in males than in females (mean 0.99 vs 0.30).Results indicate that this comprehensive and parsimonious battery is an important methodological advance because it has psychometric properties critical for the development of evidence-based classification. Measures were interrelated with body size, indicating further research is required to determine whether raw measures require normalization in order to be validly applied in classification.

Premature return to play and return to learn after a sport-related concussion: physician's chart review

OBJECTIVE

To determine what proportion of patients experience an exacerbation of their symptoms as a result of premature return to play (RTP) and return to learn (RTL) following sport-related concussions.

DESIGN

Retrospective study of electronic medical records from the office-based practice of one family and sport medicine physician who had systematically provided recommendations for cognitive and physical rest based on existing consensus recommendations. Two blinded authors independently reviewed each chart, which included Sport Concussion Assessment Tool (SCAT) and SCAT2 symptom self-report forms to determine whether an athlete had returned to play or learn prematurely. If there was a discrepancy between the 2 reviewers then a third author reviewed the charts.

SETTING

A sport medicine and family practice in Ontario. The physician assessed sport-related concussions after self-referral or referral from other primary care physicians, teams, and schools.

PARTICIPANTS

A total of 170 charts of 159 patients were assessed for sport-related concussion during a 5-year period (April 2006 to March 2011). All participants were students who were participating in sports at the time of injury. There were 41 concussions in elementary students, 95 concussions in high school students, and 34 concussions in college or university students.

MAIN OUTCOME MEASURES

Premature RTP and RTL were defined as chart records documenting the recurrence or worsening of symptoms that accompanied the patients' RTP or RTL. Measures were compared using the earliest available SCAT forms and self-reporting.

RESULTS

In 43.5% of concussion cases, the patient returned to sport too soon and in 44.7% of concussion cases, the patient returned to school too soon. Patients with a history of previous concussion required more days of rest before being permitted to participate in any physical activity than those patients without a previous history of concussion. Elementary school students required fewer days of rest before being permitted to return to any physical activity compared with high school students and college or university students.

CONCLUSION

Currently, physicians recommend restrictions on mental and physical activity following sport-related concussion. This is done without clear guidelines as to what cognitive rest entails for students. Further research is required to determine how to implement a management plan for student athletes to facilitate complete recovery after concussion.

Learning to track and identify players from broadcast sports videos

Tracking and identifying players in sports videos filmed with a single pan-tilt-zoom camera has many applications, but it is also a challenging problem. This paper introduces a system that tackles this difficult task. The system possesses the ability to detect and track multiple players, estimates the homography between video frames and the court, and identifies the players. The identification system combines three weak visual cues, and exploits both temporal and mutual exclusion constraints in a Conditional Random Field (CRF). In addition, we propose a novel Linear Programming (LP) Relaxation algorithm for predicting the best player identification in a video clip. In order to reduce the number of labeled training data required to learn the identification system, we make use of weakly supervised learning with the assistance of play-by-play texts. Experiments show promising results in tracking, homography estimation, and identification. Moreover, weakly supervised learning with play-by-play texts greatly reduces the number of labeled training examples required. The identification system can achieve similar accuracies by using merely 200 labels in weakly supervised learning, while a strongly supervised approach needs a least 20,000 labels.

Empirical verification of the weighted system of criteria for the elite water polo players quality evaluation

The aim of this research was to check the validity of the weighed system of criteria for evaluating the actual quality of water polo players proposed by Hraste, Dizdar and Trninić. The authors have determined the attributes of the measurement instrument for assessment of the overall performance efficiency of elite water polo players. Based on the determined descriptive indicators, on the coefficients of the relative importance of criteria, and on the degree of the objectivity level (interobservers' agreement) of the expert evaluations, it can be concluded that the measuring attributes (objectivity and sensitivity) for most of the criteria are in accordance with their relative importance coefficients for a particular position in the game. Consequently, a structure of relevant criteria is proposed for each play action position in the water polo game. The established instrument for evaluation the actual quality of the elite water polo players is a precondition to establish the professional system orientation, but it would also mean and a hypotheses for adequate design tactic model of play and a process of sports preparation. In succeeding steps of developing the system of criteria and its applicability, the latent structure of the criteria variables should be determined as well as overall importance of criteria with respect to the game of water polo.