Reduction in blood pressure and metabolic profile in overweight hypertensive boys participating in a 12-week aerobic exercise program.

Strategies for controlling hypertension include reducing excess fat and increasing muscle mass. However, the effects of exercise interventions on hypertension in adolescents have been little investigated. The purpose was to evaluate the effect of 12 weeks of aerobic exercise on systolic blood pressure (SBP) and diastolic blood pressure (DBP) and the cardiometabolic profile of overweight hypertensive and non-hypertensive boys. The sample included 107 boys diagnosed as overweight, aged between 12 and 17, divided into two non-hypertension groups, one control (GCN, n = 14) and one with exercise (GEN, n = 55), as well as two groups of hypertensives, one control (GCH, n = 12) and one with exercise (GEH, n = 26). The boys were assessed at the study baseline and after 12 weeks in terms of anthropometric parameters, biological maturation, SBP, DBP and mean blood pressure (MBP), lipid, and metabolic profile. The aerobic training programs lasted 12 weeks and were carried out in three weekly sessions at different intensities. The high-intensity interval training session lasted around 35 min at an intensity of 80-100% of the reserve heart rate, and the moderate-intensity of continuous training session lasted 60 min at an intensity of 35-75% of the reserve heart rate. Caloric expenditure was equivalent between the exercises (p = 0.388). CGN and CGH participated only in school physical activities. Repeated measures analysis of variance and clinical effect analysis using Cohen's effect size were used, with a significance level established at p < 0.05. After 12 weeks, all groups increased their height (p < 0.05), but only the exercise groups showed a reduction in anthropometric variables (p < 0.05), with a possibly beneficial effect in GEN (d = - 0.203; p = 0.003). No differences were found in the variables for the GCN. The GCH and GEH groups reduced SBP (p < 0.05), but only GEH showed a reduction in DBP (p = 0.005) and MBP (p = 0.001). In relation to the lipid profile, GEH maintained HDL-c close to baseline values, while GCH showed a reduction in HDL-c (p = 0.021). Regarding the clinical effect of exercise on hypertension, GEH showed a large and very beneficial effect size on DBP (d = - 0.916; p = 0.006) and MBP (d = - 0.926; p = 0.005).Conclusion: Hypertensive boys who practiced physical exercise showed greater effects in reducing blood pressure, indicating the importance of non-drug therapeutic management in overweight adolescents.Trial registration:Brazilian Registry of Clinical Trials RBR-4v6h7b / RBR-6343y7.

Biological maturation, fat mass and cardiorespiratory fitness in prepubescent girls: A mediation analysis.

BACKGROUND: The association between indicators of maturation and measures of physical fitness are not well correlated and vary according to chronological age, sex, body size, and motor characteristics. It is known that chronological age, maturation, and fat mass are significant predictors of cardiorespiratory fitness in girls, however, the contributions of fat mass to the relationship between maturation and endurance performance are still unclear. OBJECTIVE: The current study aimed to examine whether the association between somatic maturation and running performance in the 20-m shuttle-run in girls is mediated by estimated fat mass. METHODS: The sample comprised 67 girls, aged 8.00-8.99 years. Stature, body mass, and skinfolds were measured. Estimates of body composition and predicted mature stature (PMS) were then calculated. Current stature was expressed as a percentage of PMS and somatic maturation was given by z-scores of the percentage of PMS. Mediation analysis was performed using the bias-corrected bootstrap approach with 5000 resamples in order to obtain estimates of total, direct, and indirect effects of z-scores of the percentage of PMS on 20-m shuttle-run performance mediated by fat mass. RESULTS: The results show that fat mass mediated the negative effect of biological maturation on 20-m shuttle-run performance in the observed sample of prepubescent girls (Indirect effect: ß = -0.177, 95%CI: -0.291 to -0.059). CONCLUSION: Although the participants were prepubescent girls, poorer aerobic running performance appeared to be partly due to increased levels of fat mass.

Biocultural correlates of gross motor coordination in prepubescent children: A cross-sectional study.

AIM: This study aimed to explore the association of gross motor coordination (GMC) with a matrix of biocultural factors in prepubescent children, taking into account weight status, somatic maturation, sociodemographic variables, and type of school. METHODS: One hundred twenty-nine prepubescent children, of both sexes, aged between 8.00 and 8.99, were assessed for GMC (Körperkoordinationstest Für Kinder - KTK), weight status, biological maturation (predicted mature stature), sex, mother's education level and type of school. Binary logistic regression was used to examine the relationship between higher values of KTK and associated biocultural factors. RESULTS: Normoponderal children are more likely to attain better total KTK scores than those with overweight or obesity (OR: 2.942; LC 95%: 1.189, 7.280). In addition, children who are more advanced in terms of biological maturation exhibited significantly lower odds of being in the high KTK category than their less advanced peers (OR: 0.670; LC 95%: 0.474,0.946). Sex, mother's education level and the type of school are not associated with higher performance on KTK. CONCLUSION: Weight status and biological maturation are associated with motor competence in prepubescent children. Future studies should consider additional correlates to better understand the complex interactions between biological, psychosocial and behavioral factors in the prediction of motor competence.

Resistance training presents beneficial effects on bone development of adolescents engaged in swimming but not in impact sports: ABCD Growth Study.

BACKGROUND: Sports practice during adolescence is important to enhance bone development, although it may provide different effects depending on the mechanical impact present in the sport. Besides, resistance training (RT) may also induce bone changes directly (via muscle contractions) and indirectly (via myokines). However, there have been no studies analyzing the longitudinal influence of engaging in sport with and without added mechanical load. Thus, this study aims to analyze the combined effects of sports participation and resistance training on areal bone mineral density (aBMD) accrual in adolescent athletes participating in swimming and impact sports for 12-months. METHODS: This was a 12-month longitudinal study. The sample comprised 91 adolescents (21 females) aged 10 to 18 years, engaged in impact sports (basketball, tennis, track & field, baseball and gymnastics, n = 66) and non-impact sport (swimming, n = 25). The sample was divided according to resistance training participation: impact sports only (n = 45), impact sports + resistance training (n = 21), swimming-only (n = 17) and swimming + resistance training (n = 8). aBMD and soft tissues were measured using dual-energy X-ray absorptiometry. Generalized linear models analysis was used for the resistance training (RT) x type of sport interaction in predicting aBMD changes overtime, adjusting for maturation, sex and baseline aBMD. RESULTS: After 12-months, all groups showed a significant increase in aBMD, except for the swimming groups (regardless of resistant training), which showed a significant loss in spine aBMD (-0.045 [-0.085 to -0.004] g/cm2 in swimming-only and - 0.047 [-0.073 to -0.021] g/cm2 in swimming + RT). In comparisons between groups, only swimming + RT group, compared with swimming-only group presented higher upper limbs aBMD (0.096 g/cm2 [0.074 to 0.118] in swimming + RT vs. 0.046 [0.032 to 0.060] g/cm2 in swimming only; p < 0.05) and whole body less head (WBLH) aBMD (0.039 [0.024 to 0.054] g/cm2 in swimming + RT vs. 0.017 [0.007 to 0.027] g/cm2 swimming-only; p < 0.05). CONCLUSION: Despite the significant gain in aBMD in all groups and body sites after 12-months, except for the spine site of swimmers, the results indicate that participation in RT seems to improve aBMD accrual in swimmers at the upper limbs and WBLH.

Ages at peak height velocity in male soccer players 11-16 years: relationships with skeletal age and comparisons among longitudinal studies.

Estimated ages at take-off (TO) and at peak height velocity (PHV) based on two models and maturity status based upon age at PHV and skeletal age (SA) were compared in a longitudinal sample of male soccer players. In addition, estimated ages at PHV in 13 longitudinal samples of soccer players were compared. The longitudinal height records of 58 players of European ancestry, measured annually on four or five occasions between 11 and 16 years, were modeled with Superimposition by Translation and Rotation (SITAR) and Functional Principal Component Analysis (FPCA) to estimate ages at TO and PHV. SAs were assessed with the Fels method. Ages at PHV in 13 longitudinal samples of soccer players (Europe 7, Japan 6) were evaluated with meta-analysis. Estimated ages at TO, 11.2 ± 0.8 (SITAR) and 11.0 ± 0.8 (FCPA) years, and at PHV, 13.6 ± 0.9 (SITAR) and 13.7 ± 0.0 (FCPA) years, were similar. An earlier age at PHV was associated with advanced skeletal maturity status (rho = -0.77 at ~14 years). Ages at PHV among European players indicated a north (later) - south (earlier) gradient, and were later than ages at PHV among Japanese players. In summary, ages at TO and PHV were similar with SITAR and FPCA, and ages at PHV were most strongly correlated with SA at ~14 years. Mean ages at PHV showed a north-south gradient among European samples, and were later compared to Japanese samples.

Endurance training improves heart rate on-kinetics in women with subclinical hypothyroidism: a preliminary study.

PURPOSE: The aim of the study was to evaluate the effect of endurance training on heart rate (HR) on-kinetics in patients with subclinical hypothyroidism (SH). METHODS: Eighteen women were randomly assigned to trained group (TG) or control group (CG). Both groups performed three tests at 50 W in a cycle ergometer for 6 min. HR kinetics was obtained during the tests and the mean response time (MRT), which is equivalent to the time taken to reach 63% of the HR at steady state, was extracted. The TG was then submitted to 12 weeks of endurance training (50 min, 3x/week, intensity between 70 and 85% of the maximum HR predicted for the age). Statistical analysis was performed by the mixed analysis of variance. RESULTS: At baseline, TG and CG were similar for TSH (7.7 ± 3.1 vs. 6.9 ± 3.3 mUI/L, p = 0.602, respectively) and FT4 (12.31 ± 1.51 vs. 12.20 ± 1.89 pmol/L, p = 0.889, respectively). After adjustment for body mass index and age, interactions between moment (baseline or after 12 weeks) and group (trained or control) were only significant for MRT (TG: 39.6 ± 10 to 28.9 ± 8.4 s, CG: 53.6 ± 20.3 to 55 ± 19.7 s, p = 0.001) and physical activity level (CG: 7.3 ± 0.7 to 8 ± 0.9, CG: 6.8 ± 0.8 in both moments, p = 0.005). CONCLUSION: The preliminary results suggest that 12 weeks of endurance training improve HR on-kinetics and physical activity level in SH.

Physical fitness trends in a nationally representative sample of Portuguese youth: What has changed from 2008 to 2018?

This investigation aimed to describe the current physical fitness (PF) status of Portuguese youth, compare secular trends from 2008 and 2018, and establish updated age- and sex-specific percentile values for distinct PF tests. In 2008 and 2018, 22 048 and 8960 children and adolescents (10-18 years) were included in two national cross-sectional investigations. PF was evaluated using the FITESCOLA® battery tests and the handgrip strength test. Independent sample t-tests and chi-squared tests were used to model the results. Weight smoothed percentile values were calculated using Cole's Lambda-Mu-Sigma (LMS) method. All analyses were weighted according to age, sex, and geographic region. In 2018, boys surpassed girls in the 20-m shuttle run, curl-ups, push-ups, standing long, and vertical jump tests, while girls performed better in the sit-and-reach (p < 0.05). The percentage of boys and girls meeting the healthy zone in the 20-min shuttle run test did not differ between 2008 and 2018 (p ≥ 0.05). In boys, a higher percentage fell in the healthy zone for the curl-up and push-up tests in 2018 compared to 2008 (85.8% vs. 83.4%, and 57.8% vs. 53.8%; p < 0.05). Girls improved their flexibility component (sit-and-reach test), with a higher percentage meeting the healthy zone in 2018 (32.6% vs. 36.9%; p < 0.05); an opposite trend was seen for boys (65.5% vs. 50.1%; p < 0.05). The present investigation provides new and updated PF percentile curves for Portuguese youth, which can be used as a general overview of the current PF state among the Portuguese young population.

Interrelationship between muscle fitness in childhood and bone mineral density in adulthood: mediation analysis of muscle fitness in adulthood.

BACKGROUND: This study was aimed to examine the relationship between muscular fitness indicators in childhood and areal bone mineral density (aBMD) in adulthood and to verify whether the relationship is mediated by performance on muscular fitness indicators in adulthood. METHODS: A sample of 138 healthy adults (69 males; 22.3 years) were followed after a previous assessment at the age of 7-10 years. Stature, body mass and muscular fitness indicators (handgrip strength, standing long jump and sit-ups tests) were assessed in childhood and adulthood. Additionally, total body, upper limbs, lower limbs, right femoral neck and lumbar spine aBMD was assessed in adulthood using dual X-ray absorptiometry. Analysis included descriptive statistics; t-test or Mann-Whitney U-test for comparison between males and females, multiple linear regression for the prediction aBMD from muscular fitness indicators in childhood, mediation analysis of the respective muscular fitness indicators in adulthood and the relationship between muscular fitness indicators in childhood and aBMD. RESULTS: Males were stronger compared to females regarding muscular fitness indicators in childhood and adulthood, and presented higher mean values for aBMD in adulthood, except for lumbar spine (p < 0.05). Regression analysis revealed that some muscular fitness indicators in childhood showed significant positive relationship with bone health indicators in adulthood, such as: handgrip strength and total body aBMD (ß = 0.005; R2 = 0.35; p = 0.040) and upper limbs aBMD (ß = 0.005; R2 = 0.55; p = 0.019); and sit-ups test was a significant predictors of lumbar spine BMD (ß = 0.003; R2 = 0.06; p = 0.039). Mediation analysis pointed out the following: adulthood handgrip strength mediated relationships between childhood handgrip strength and total aBMD (indirect effect (IE) = 0.0025; 95%CI = 0.0005-0.0048), and upper limbs aBMD (IE = 0.0040; 95%CI = 0.0017-0.0069). CONCLUSIONS: Muscular fitness indicators in childhood showed significant relationship with bone health indicators in adulthood and the sit-ups test in childhood had direct effect on lumbar spine aBMD in adulthood. Adulthood handgrip strength mediated the relationship between childhood handgrip strength and total body and upper limb aBMD, pointing out that muscular fitness in childhood may be a aBMD determinant in adulthood, especially when higher muscle fitness performance is maintained in adulthood.

Intra-observer reproducibility and inter-observer agreement of Fels skeletal age assessments among male tennis players 8-16 years.

BACKGROUND: Skeletal age (SA) is an estimate of biological maturity status that is commonly used in sport-related medical examinations. This study considered intra-observer reproducibility and inter-observer agreement of SA assessments among male tennis players. METHODS: SA was assessed with the Fels method in 97 male tennis players with chronological ages (CA) spanning 8.7-16.8 years. Radiographs were evaluated by two independent trained observers. Based on the difference between SA and CA, players were classified as late, average or early maturing; if a player was skeletally mature, he was noted as such as an SA is not assigned. RESULTS: The magnitude of intra-individual differences between repeated SA assessments were d = 0.008 year (observer A) and d = 0.001 year (observer B); the respective coefficients of variation were 1.11% and 1.75%. Inter-observer mean differences were negligible (t = 1.252, p = 0.210) and the intra-class correlation coefficient was nearly perfect (ICC = 0.995). Concordance of classifications of players by maturity status between observers was 90%. CONCLUSION: Fels SA assessments were highly reproducible and showed an acceptable level of inter-observer agreement between trained examiners. Classifications of players by skeletal maturity status based on assessments of the two observers were highly concordant, though not 100%. The results highlight the importance of experienced observers in skeletal maturity assessments.

Body Size, Fatness and Skeletal Age in Female Youth Soccer Players.

Growth and maturation are central concerns in the organization of training and competitions in youth sports. This study examined maturity-associated variation in body size and adiposity among adolescent girls participating in competitive age group youth soccer. The sample included 441 players 10.08-16.73 years of age. Stature and body mass were measured and body composition was predicted. The Fels method was used to estimate skeletal age. Skeletally maturity status (late, average or early maturing) was based on the difference between chronological and skeletal age for each player. Mean stature approximated the 50th percentiles of the general population in all competitive age groups, while mean weight fluctuated between 50th and 75th percentiles. Age- and maturity-specific means for estimated fat mass ranged between 18.0% and 28.2%. The number of players classified as skeletally mature increased with competitive age groups (under-13: 0%; under-15: 8%; under-17: 49%). In general, early maturing girls tended to be heavier than their age group peers and especially when compared to late maturing players.

Results from Portugal's 2022 report card on physical activity for children and youth.

Background: The purpose of this study is to update results of Portuguese's Report Card on Physical activity (PA) for Children and Adolescents. Methods: The grades were assigned by results derived from the PA and Fitness in Portugal 2021 Portuguese Report Card and corresponds to the third report for the Portuguese children and adolescents. It includes indicators of PA and sedentary behavior (SB) that are common to the GLOBAL matrix 4.0: Overall Physical Activity, Organized Sport and Physical Activity, Active Play, Active Transportation, Sedentary Behaviors, Family and Peers, School, Community and the Environment, Government and Physical Fitness. The search focused on published national evidence/data sources (academia, NGO, governmental) from end 2018 onwards excluding data obtained during the covid-19 pandemic. Results: The grades were assigned as follows: Overall PA (D-), Organized Sport Participation (C-), Active Play (D+), Active Transportation (D-), Sedentary behaviors (C+), Physical Fitness (C), Family and Peers (B), School (A), Community and Environment (B), and Government (B). Conclusion: In line with previous Portuguese Report Cards, a large proportion of Portuguese children and adolescents are not sufficiently active nor fit enough setting urgency for effective strategies. Particular attention should be given to Active play, Active transport and Organized Sports Participation has their grades have decreased. Some actions in selected indicators as Governmental and policy seems promising however results weren't seen yet. Despite the strong support of schools with mandatory curricula in PE no correspondent change is observed in fitness or PA, so more research is needed to find why.

Assessment of skeletal age in youth female soccer players: Agreement between Greulich-Pyle and Fels protocols.

OBJECTIVE: The purpose of the study was to evaluate the agreement between the Fels and Greulich-Pyle methods for the assessment of skeletal age (SA) in female youth soccer players. METHODS: The sample included 441 Portuguese players 10.08-16.73 years of age who regularly participated in organized and competitive soccer. Standardized radiographs of the left hand-wrist were obtained and analyzed by an experienced examiner. SA was estimated with the Fels and Greulich-Pyle (GP) methods. Differences between SA and chronological age (CA) were used to define skeletal maturity groups: late, average and early maturing. In addition to descriptive statistics, Cohen's kappa and Lin concordance correlation coefficients were used to evaluate agreement between methods. RESULTS: Intraindividual differences in SA based on the two methods varied between 0.10 to 1.47 years among age groups with larger mean differences at older ages. Agreement of maturity classifications between methods was 74% at younger ages (under-13: kappa = 0.48; under-14: kappa = 0.39; Lin CCC = 0.68) and declined with increasing CA (under-17: 19% agreement; kappa = 0.001; Lin CCC = 0.11). About 19% of the total sample was skeletally mature with the Fels method and an SA was not assigned; in contrast, no players were skeletally mature with the GP method. CONCLUSIONS: GP SAs were systematically lower than Fels SAs among female soccer players. Intraindividual variability in SAs between methods was considerable. The findings highlight the impact of method on estimates of maturity status.

Growth, body composition and bone mineral density among pubertal male athletes: intra-individual 12-month changes and comparisons between soccer players and swimmers.

BACKGROUND: Puberty is a period of intense changes in human body and, additionally, participation in sports is viewed as prominent form of physical activity among male adolescent athletes. The current study was aimed to examine the intra-individual changes in body composition and bone tissue during years of maximal growth and the effect of 12-month participation in sports contrasting in mechanical impact. METHODS: The sample included 40 male adolescent athletes (soccer: n = 20; swimming: n = 20) aged 12.57 ± 0.37 years who were followed for 12 months. Stature and body mass were measured, bone mineral content (BMC), areal bone mineral density (aBMD), lean soft and fat tissues assessed using DXA. Food intake was estimated using a questionnaires and training sessions individually monitored. Repeated measures ANOVA tested the differences between sports and 12-month intra-individual variation (time moments: TM1, TM2). The analyses on aBMD for total body and total body less head were repeated controlling for variation in stature at baseline. RESULTS: Soccer players completed 63 ± 31 sessions (95 ± 47 h). Respective values for swimmers were 248 ± 28 sessions and 390 ± 56 h. In general, the analysis of aBMD as dependent variable evidenced significant effect of sport-associated variation (F = 5.254, p < 0.01; η2 = 0.35) and 12-month increments, particularly at lower limbs (F = 97.238, p < 0.01; η2 = 0.85). Respective mean values for aBMD were SCCTM1 = 0.885 g.cm-2, SWMTM1 = 0.847 g.cm-2, SCCTM2 = 0.939 g.cm-2, SWMTM2 = 0.880. Regarding the lean soft tissue, the magnitude of effects was very large for intra-individual variation (F = 223.043, p < 0.01; η2 = 0.92) and moderate between sports (F = 7.850, p < 0.01; η2 = 0.41): SCCTM1 = 30.6 kg, SWMTM1 = 34.9 kg, SCCTM2 = 35.8 kg, SWMTM2 = 40.5 kg). Finally, d-cohen values reporting percentage of intra-individual changes in aBMD between soccer players ad swimmers were large for the trochanter (d = 1.2; annual increments: SCC = 8.1%, SWM = 3.6%). CONCLUSION: Puberty appeared as a period of significant intra-individual changes in lean soft tissue and bone mineral density. With increasing accumulated training experience, mean difference between sports contrasting in mechanical impact tended to me more pronounced in particular at the lower limbs.

Growth and maturity status of young male table tennis players.

A maturity-associated gradient among adolescent athletes in many sports tends to favour early maturing participants. This study was aimed to describe inter-individual variance in growth and skeletal maturation among male youth table tennis. The sample included 99 players registered in competitive clubs for at least 2 years. Chronological age (CA) ranged 10.00-14.63 years. Stature and body mass were plotted relative to US references. Skeletal age (SA) was estimated with the Fels method. Maturity status was given as SA minus CA. Somatic maturation was derived from predicted age at peak height velocity. Mean values for stature and weight were above the reference medians from 10 to 13 years and at the median in the oldest group. In general, SA was in advance to CA (CA: 12.45 ± 1.28 years; SA: 13.44 ± 2.37 years). The majority of the players were early maturing according to SA (52%) and average maturing based on the somatic indicator (80%). The results suggested that table tennis tends to retain taller and heavier participants who are somewhat advanced in skeletal maturity. Participation in youth table tennis and opportunities to win need to consider age- and maturity-associated variations, particularly regarding bands for competitions.

Allometric Scaling of Force-velocity Test Output Among Pre-pubertal Basketball Players.

Basketball is characterized by high-intensity episodes predominantly reliant on anaerobic metabolism. The force-velocity test enables individual determination of an optimal braking force and emerged as appropriate to estimate optimal peak power. It has rarely been used in youth basketball. This study aimed to examine the contribution of body size, composition, and biological maturation to interindividual variation in force-velocity test output among pre-pubertal basketball players. The sample consisted of 64 male participants (8.4-12.3 years). Stature, sitting height, body mass and two skinfolds were measured, and leg length estimated. Fat-free mass and lower limb volume were estimated from anthropometry. Age at peak height velocity was predicted from maturity offset. Optimal peak power was correlated with all body size descriptors (correlation: 0.541-0.700). Simple allometric models explained 30-47% of inter-individual variance, with fat-free mass being the best predictor of performance. Whole-body fat-free mass (as a surrogate for active muscle mass) plus the indicator of maturation emerged as the best proportional allometric model (53% explained variance). Even at pre-pubertal ages, the interpretation of the force-velocity test requires assessing the metabolically active component of body mass.

Longitudinal development of 5m sprint performance in young female tennis players.

Sprint performance over short distances is a central component in young tennis players' development. This study aimed to examine the longitudinal development of sprint performance in young female tennis players, and to investigate differences between performance levels. Also potentially explanatory variables were investigated. Female tennis players aged 10-15 (N = 167) participated in a, mixed-longitudinal study (n = 48 elite; n = 119 sub-elite). Players were measured annually on the 5 m sprint as well as for possible explaining variables for 5 m sprint performance development (age, height, body mass, maturity status, lower limb explosive strength). Multilevel analysis was used to obtain a developmental model. Moreover, it was possible to predict sprint performance (5 m) based on chronological age, body size given by height, and lower limb strength performance (p < .05). Significant different developmental patterns were found for elite and sub-elite players, with elite players aged 10-14 being faster. After age 14, no significant differences were found in sprint performance between elite and sub-elite players (p > . 05). Sprint performance is an important characteristic of young female tennis players and seemed to depend on growth and maturation in parallel to physical fitness.

Characteristics of select and non-select U15 male soccer players.

Baseline characteristics of 31 healthy male U15 soccer players who were classified as select or non-select at the end of the season were compared. Players were 14.4 ± 0.54 years (13.6-15.3 years) at baseline; characteristics included body size, proportions and composition, estimated maturity status, several functional capacities, and coach classifications of potential in the sport. Decisions regarding selection or non-selection were made about two months after baseline. Select and non-select U15 soccer players differed significantly in estimated maturity status, body size, proportions and estimated muscle mass, functional tests related to speed, power and strength, and coach evaluation of potential, specifically tactical skills on offense and skills associated with creativity and decision making. When age and biological maturity status were statistically controlled, select and non-select players differed significantly only on the vertical jump, grip strength, and coach ratings of tactical skills on offense and of creativity and decision making. Results of stepwise discriminant analysis highlighted the importance of coach evaluation of tactical skills associated with offense, and of power and strength in distinguishing select from non-select players. The results highlight the advantages of advanced biological maturity status among adolescent male soccer players and also the importance of coach perceptions of talent. The latter implies a need for further study of the basis of coach perceptions, specifically how they are influenced by and perhaps interact with player characteristics at different ages, and how the perceptions influence playing time and player behaviors and interactions.

Novel PCR primers for improved detection of Mycobacterium leprae and diagnosis of leprosy.

AIMS: Diagnosis of leprosy, a chronic infection caused by Mycobacterium leprae, predominantly depends on clinical manifestations and histopathological analysis, hampering rapid and accurate diagnostics. Our aim was to increase accuracy of leprosy diagnosis by improving M. leprae's DNA detection based on polymerase chain reaction (PCR) technique using new specific primers for the RLEP repetitive sequence. METHODS AND RESULTS: The specific target region, RLEP, of M. leprae's genome was selected based on comparative genomics. After confirming the specificity of this region, using blastn analysis, primers were designed and tested for their in silico specificity. To evaluate the specificity and sensitivity of these primers in vitro, 184 blood samples from patients were used in qPCR. The new primer pair LYON1/LYON2 produced 91% positive samples, whereas the current primer pair LP1/LP2 produced 46%. Specificity and DNA detection limit test were carried out to compare the efficiency of the developed primer pair. The LYON1/LYON2 primer showed 100% specificity, whereas LP1/LP2 showed 64%. The DNA detection limit of LYON1/LYON2 was 10 copies of bacterial genomes per millilitre, whereas LP1/LP2 was 1000 copies of bacterial genomes per millilitre. CONCLUSIONS: In conclusion, the developed LYON1/LYON2 primer pair presented to be a specific and sensitive new molecular marker for the diagnosis of leprosy. SIGNIFICANCE AND IMPACT OF THE STUDY: The development of a specific primer pair for the detection of the M. leprae genome through qPCR technique contributes to a fast, sensitive and specific diagnosis, which is essential to prevent spreading and progression of this disease.

Reproducibility and inter-observer agreement of Greulich-Pyle protocol to estimate skeletal age among female adolescent soccer players.

BACKGROUND: Skeletal age (SA) is considered the best method of assessing biological maturation. The aim of this study was to determine intra-observer (reproducibility) and inter-observer agreement of SA values obtained via the Greulich-Pyle (GP) method. In addition, the variation in calculated SAs by alternative GP protocols was examined. METHODS: The sample was composed of 100 Portuguese female soccer players aged 12.0-16.7 years. SAs were determined using the GP method by two observers (OB1: experience < 100 exams using GP; OB2: experience > 2000 exams using several methods). The radiographs were examined using alternative GP protocols: (wholeGP) the plate was matched to the atlas as an overall approach; (30-boneGP) bone-by-bone inspections of 30-bones; (GPpmb) bone-by-bone inspections of the pre-mature bones only. For the 30-boneGP and GPpmb approaches, SA was calculated via the mean (M) and the median (Md). RESULTS: Reproducibility ranged 82-100% and 88-100% for OB1 and OB2, respectively. Inter-observer agreement (100 participants multiplied by 30 bones) was 92.1%. For specific bones, agreement rates less than 90% were found for scaphoid (81%), medial phalange V (83%), trapezium (84%) and metacarpal V (87%). Differences in wholeGP SAs obtained by the two observers were moderate (d-cohen was 0.79). Mean differences between observers when using bone-by bone SAs were trivial (30-boneGP: d-cohen less than 0.05; GPpmb: d-cohen less than 0.10). The impact of using the mean or the median was negligible, particularly when analyses did not include bones scored as mature. CONCLUSION: The GP appeared to be a reasonably reproducible method to assess SA and inter-observer agreement was acceptable. There is evidence to support a recommendation of only scoring pre-mature bones during later adolescence. Further research is required to examine whether these findings are consistent in younger girls and in boys.

Scaling left ventricular mass in adolescent female soccer players.

BACKGROUND: The aim of the study was to examine the contribution of chronological age (CA), skeletal maturation, training experience and concurrent body size descriptors, to inter-individual variance in left ventricular mass (LVM) among female adolescent soccer players. METHODS: The sample included 228 female soccer players 11.8-17.1 years. Training experience defined as years of participation in competitive soccer (range 2-9 years), was obtained by interview. Stature, body mass and skinfolds (triceps, medial calf) were measured. Fat mass was estimated; Fat-free mass was derived. LVM was assessed by echocardiography. Skeletal maturity status was as the difference of skeletal age (SA, Fels method) minus CA. RESULTS: Fat-free mass was the most prominent single predictor of LVM (R2 = 36.6%). It was associated with an allometric coefficient close to linearity (k = 0.924, 95%CI: 0.737 to 1.112). A significant multiplicative allometric model including body mass, fat-free mass, CA, training experience and skeletal maturity status was also obtained (R = 0.684; R2 = 46.2%). CONCLUSION: Stature has limitations as a valid size descriptor of LVM. Body mass, fat-free mass, training experience, CA, body mass and skeletal maturity status were relevant factors contributing to inter-individual variability in LVM.