Value of Magnetic Resonance Imaging for Skeletal Bone Age Assessment in Healthy Male Children.

BACKGROUND: Skeletal bone age assessment for medical reasons is usually performed by conventional x-ray with use of ionizing radiation. Few pilot studies have shown the possible use of magnetic resonance imaging (MRI). PURPOSE: To comprehensively evaluate feasibility and value of MRI for skeletal bone age (SBA) assessment in healthy male children. MATERIALS AND METHODS: In this prospective cross-sectional study, 63 male soccer athletes with mean age of 12.35 ± 1.1 years were examined. All participants underwent 3.0 Tesla MRI with coronal T1-weighted turbo spin echo (TSE), coronal proton density (PD)-weighted turbo spin echo (TSE), and T1-weighted three-dimensional (3D) volume interpolated breath-hold examination (VIBE) sequence. Subsequently, SBA was assessed by 3 independent blinded radiologists with different levels of experience using the common Greulich-Pyle (GP) atlas and the Tanner-Whitehouse (TW2) method. RESULTS: In a mean total acquisition time of 5:04 ± 0:47 min, MR image quality was sufficient in all cases. MRI appraisal was significantly faster ( P < 0.0001) by GP with mean duration of 1:22 ± 0:08 min vs. 7:39 ± 0:28 min by TW. SBA assessment by GP resulted in mean age of 12.8 ± 1.2 years, by TW 13.0 ± 1.4 years. Interrater reliabilities were excellent for both GP (ICC = 0.912 (95% confidence interval [CI] = 0.868-0.944) and TW (ICC = 0.988 (95% CI = 0.980-0.992) and showed statistical significance ( P < 0.001). Subdivided, for GP, ICCs were 0.822 (95% CI = 0.680-0.907) and 0.843 (95% CI = 0.713-0.919) in Under 12 and Under 14 group. For TW, ICCs were 0.978 (95% CI = 0.958-0.989) in Under 12 and 0.979 (95% CI = 0.961-0.989) in Under 14 group. CONCLUSION: MRI is a clinically feasible, rapidly evaluable method to assess skeletal bone age of healthy male children. Using the Greulich-Pyle (GP) atlas or the Tanner-Whitehouse (TW2) method, reliable results are obtained independent of the radiologist's experience level.

The effectiveness of 3D multiple object tracking training on decision-making in soccer.

BACKGROUND: Soccer requires athletes to make quick decisions in dynamic environments. Several off-court technology-based interventions have been developed to train these perceptual cognitive skills. However, the evidence for training transfer using technologies to athletic performance has been sparse. Previous research found 3-dimensional multiple object tracking (3D MOT) training to cause a significant increase in quality of passing decision-making. Limitations to the research warrant further investigation of this association. PURPOSE: To re-examine the effectiveness of 3D MOT on training decision-making. METHODS: Thirty-one NCAA Division III soccer players (female n = 16) were randomized to 3D MOT training or a control task. The experimental group received 10 training sessions over a span of 4 weeks. RESULTS: The manipulation check indicated a significant training effect in 3D MOT performance for the intervention but not the control group (F(1,29) = 21.46, p < .001, np2 = .43). Non-significant changes with small effect sizes (np2 = .01-.03) in decision-making and measures of near-transfer were found. CONCLUSION: The findings challenge the association between 3D MOT training and increased quality of decision-making in soccer.

Nationwide Subjective and Objective Assessments of Potential Talent Predictors in Elite Youth Soccer: An Investigation of Prognostic Validity in a Prospective Study.

Recent studies have provided empirical evidence on the prognostic relevance of objective performance diagnostics in the soccer talent identification and development process. However, little is known about the prognostic validity of coaches' subjective evaluations of performance. This study evaluated objective and subjective assessments within a nationwide talent development program and addressed motor, perceptual skill, and personality-related performance factors. Male players (N = 13,869; M age = 12.59 ± 1.07 years) from the age groups U12 to U15 of the German soccer talent development program participated in this study. Participants completed an objective motor diagnostic (sprint, agility, dribbling, ball control, juggling) and were subjectively rated by their coaches (kicking skills, endurance, individual tactical skills, psychosocial skills). All nine predictors were assessed with sufficient psychometric properties (α ≥ 0.72; except dribbling and ball control: α ≥ 0.53). Players' success three seasons later was operationalized by achieving professional youth academy level or not (success rate, 9%). Independent-samples t-tests analyzed univariate mean group comparisons between future selected and non-selected players. Logistic regression models examined the multivariate prognostic validity of all assessments by predicting success with subjective (model 1), objective (model 2), and both groups of predictors (model 3). Confirming the univariate prognostic validity, future selected outperformed non-selected players regarding all predictors (each p < 0.001, except for agility in U15: p < 0.01). Tactical skills, kicking skills, and sprint were of highest predictive value (d ≥ 0.61 in each age group). Multivariate results provided empirical evidence for the subjective (7% ≤ Nagelkerke's R 2 ≤ 11%; each p < 0.001) and objective (8% ≤ Nagelkerke's R 2 ≤ 13%; each p < 0.001) assessments' prognostic validity. However, model 3 revealed the best statistical explanatory power in each age group (0.15 ≤ Nagelkerke's R 2 ≤ 0.20; p < 0.001). In this combined assessment model, sprint, tactical skills, and dribbling were found to be the most predictive variables. In conclusion, this study reinforces the call for multidimensional diagnostics integrating objective and subjective assessments. Future research is needed to address the demands for longitudinal analyses of subjective ratings, the integration of biological maturation, and empirical evidence for female soccer.

Biological Maturity Status in Elite Youth Soccer Players: A Comparison of Pragmatic Diagnostics With Magnetic Resonance Imaging.

The influence of biological maturity status (BMS) on talent identification and development within elite youth soccer is critically debated. During adolescence, maturity-related performance differences within the same age group may cause greater chances of being selected for early maturing players. Therefore, coaches need to consider players' BMS. While standard methods for assessing BMS in adolescents are expensive and time-consuming imaging techniques (i.e., X-ray and MRI), there also exist more pragmatic procedures. This study aimed to evaluate commonly used methods to assess BMS within a highly selected sample of youth soccer players. A total of N = 63 elite male soccer players (U12 and U14) within the German Soccer Association's talent promotion program completed a test battery assessing BMS outcomes. Utilizing MRI diagnostics, players' skeletal age (SAMRI) was determined by radiologists and served as the reference method. Further commonly used methods included skeletal age measured by an ultrasound device (SAUS), the maturity offset (MOMIR), and the percentage of adult height (PAHKR). The relation of these alternative BMS outcomes to SAMRI was examined using different perspectives: performing bivariate correlation analyses (1), modeling BMS as a latent variable (BMSlat) based on the multiple alternative diagnostics (2), and investigating individual differences in agreement (3). (1) Correlations of SAMRI and the further BMS variables ranked from r = 0.80 to r = 0.84 for the total sample and were lower for U12 (0.56 ≤ r ≤ 0.66), and U14 (0.61 ≤ r ≤ 0.74) (2). The latent structural equation modeling (SEM) (R 2 = 51%) revealed a significant influence on BMSlat for MOMIR (ß = 0.51, p <0.05). The additional contribution of PAHKR (ß = 0.27, p = 0.06) and SAUS (ß = -0.03, p = 0.90) was rather small (3). The investigation of individual differences between the reference method and alternative diagnostics indicated a significant bias for MOMIR (p <0.01). The results support the use of economical and time-efficient methods for assessing BMS within elite youth soccer. Bivariate correlation analyses as well as the multivariate latent variable approach highlight the measures' usefulness. However, the observed individual level differences for some of the utilized procedures led to the recommendation for practitioners to use at least two alternative assessment methods in order to receive more reliable information about players' BMS within the talent promotion process.

The prognostic value of physiological and physical characteristics in youth soccer: A systematic review.

Talent identification and selection in soccer is typically based on subjective evaluations of experienced coaches. Recently, there has been a trend to complement these subjective assessments with objective tests. However, there is currently no comprehensive overview of the prognostic relevance of objective measurements in youth soccer. Therefore, the primary purpose of the current study was to systematically review published empirical studies related to the prognostic relevance of physiological (e.g. endurance and speed) and physical characteristics (i.e. height and weight). Of 6876 initially identified studies, nine articles were included. In those studies, endurance (nine studies), change of direction (seven), height (seven), and weight (seven) received the most meaningful consideration within the literature. In regard to physiological predictors, between 16 and 29 effect sizes were tested for endurance, sprint, and change of direction, and about half of them were found to be significant with small to moderate effects (0.37 ≤ Mdn(d) ≤ 0.57). In addition, while only investigated in two studies all tested effect sizes for repeated sprint ability were found to be significant. Despite their frequent consideration in the literature, low numbers of significant effect sizes (≤ 26%) and magnitude (0.23 ≤ Mdn(d) ≤ 0.29) were found for the physical predictors height and weight. Overall, results appear to be dependent on the respective study design and, in particular, moderator variables (i.e. soccer development stage, performance level T1/T2, prognostic period, and sample size). Consequently, additional research seems warranted to more comprehensively investigate the predictive relevance of the individual characteristics using more homogeneous study designs.

Psychological talent predictors in youth soccer: A systematic review of the prognostic relevance of psychomotor, perceptual-cognitive and personality-related factors.

Within the multidimensional nature of soccer talent, recently there has been an increasing interest in psychological characteristics. The aim of this present research was to systematically review the predictive value of psychological talent predictors and provide better comprehension of the researchers' methodological approaches and the empirical evidence for individual factors (i.e., psychomotor, perceptual-cognitive and personality-related). Results highlighted heterogeneous study designs (e.g., participants, measurement methods, statistical analyses) which may limit the comparability of studies' findings. Analyzing the number of included studies, psychomotor (n = 10) and personality-related factors (n = 8) received more consideration within the literature than perceptual-cognitive factors (n = 4). In regard to empirical evidence, dribbling (0.47 ≤ d ≤ 1.24), ball control (0.57 ≤ d ≤ 1.28) and decision-making (d = 0.81) demonstrated good predictive values as well as the achievement motives hope for success (0.27 ≤ d ≤ 0.74) and fear of failure (0.21 ≤ d ≤ 0.30). In conclusion, there is growing acceptance of the need for more complex statistical analyses to predict future superior performance based on measures of current talent. New research addresses the necessity for large-scale studies that employ multidisciplinary test batteries to assess youth athletes at different age groups prospectively.

Postharvest variation in apple (Malus x domestica Borkh.) Flavonoids following harvest, storage, and 1-MCP treatment.

The impact of 1-methylcyclopropene (1-MCP) on the synthesis and retention of flavonoid compounds during storage and ripening of red Delicious (Malus x domestica Borkh.) apples was investigated. Numerous anthocyanins, flavonols, flavan-3-ols, and a hydroxycinnamic acid from three different fruit harvest maturities were monitored after a 120 day storage and 1 week shelf life period using high-performance liquid chromatography/diode array detector analysis. The total flavonoid concentration was 5% greater in fruit treated with 1-MCP, whereas chlorogenic acid levels were 24% lower. All compounds analyzed increased in concentration during fruit harvest; however, the anthocyanins generally declined after storage, while chlorogenic acid levels increased. 1-MCP treatment resulted in the retention of anthocyanins in the latter stages of storage but did not affect the flavonols and flavan-3-ols. Chlorogenic acid biosynthesis from early and optimal fruit harvest maturities was greatly inhibited by 1-MCP during storage and the 1 week shelf life period. However, 1-MCP did not affect chlorogenic acid concentrations in late-harvested fruit. Results suggest that 1-MCP may inhibit the activity of phenylalanine ammonia-lyase and subsequent biosynthesis of flavonoid compounds. However, because very little postharvest biosynthesis of flavonoids occurs in apples, 1-MCP treatment may be useful for maintaining some of the intrinsic flavonoid levels of red Delicious apples, if applied at the proper harvest maturity.

Characterization of microsomal and mitochondrial phospholipase D activities and cloning of a phospholipase D alpha cDNA from strawberry fruits.

Phospholipase D alpha (PLD, EC 3.1.4.4)) is a key enzyme involved in membrane deterioration that occurs during fruit ripening and senescence. The biochemical and molecular characteristics of PLD was studied in strawberry (Fragaria ananassa Duch) fruits, which are non-climacteric fruits. PLD activity was primarily associated with the mitochondrial and microsomal fractions and showed increased activity during development. Optimal pH levels of activity were observed at 5.5 and 6.5 for mitochondrial PLD and at 5 and 7 for microsomal PLD. Calcium enhanced microsomal PLD activity at 1-40 microM levels. PLD activity followed Michaelis-Menten kinetics. Lineweaver-Burk analysis gave Km values in the range of 114 and 277 microM using dipalmitoylphosphatidylcholine (DPPC) as substrate for mitochondrial and microsomal PLD, respectively. The Vmax value for the microsomal PLD was nearly 12-fold higher than that of mitochondrial PLD. A 2874 bp full-length cDNA for PLD alpha was amplified from strawberry fruit mRNA using RT-PCR and 5'- and 3'-RACE encoding an 810 amino acid-polypeptide. The predicted strawberry PLD sequence showed the characteristic C2 domain and the phospholipase domains conferring calcium sensitivity and the enzyme activity, respectively. The strawberry PLD alpha showed a high degree of similarity to other PLD alphas from plants. The implications of PLD regulation during ripening of fruits are discussed.