Effects of a Pilates programme in spinal curvatures and hamstring extensibility in adolescents with thoracic hyperkyphosis: a randomised controlled trial.

AIM: To evaluate the effects of a 9-month Pilates exercise programme on the sagittal spinal posture and hamstring extensibility of adolescents with thoracic hyperkyphosis. DESIGN: Randomised controlled trial with blinded examiner. PATIENTS: One-hundred and three adolescents with thoracic hyperkyphosis. INTERVENTIONS: Participants were randomly placed into an experimental group which participated in a Pilates exercise programme implemented for a total of 38 weeks (two sessions/week, 15 min/session) (Pilates group (PG), sample = 49, or control group (CG), sample = 48). MAIN OUTCOME MEASURES: The outcome measures were the thoracic curve in sagittal spinal curvature in relaxed standing, sagittal spinal curvatures and pelvic tilt in relaxed standing and sit-and-reach positions, and hamstring extensibility. RESULTS: There was a significant adjusted mean difference between groups in favour of the PG in the thoracic curve in relaxed standing position (-5.6°, p = 0.003), pelvic tilt (-2.9°, p = 0.03) and all straight leg tests (p<0.001). The PG showed a significant change in thoracic curve (-5.9, p<0.001) and in lumbar angle (4.0, p = 0.001) in relaxed standing position and in all straight leg raise tests (+6.4 to +15°, p<0.0001). CONCLUSIONS: The adolescents with thoracic hyperkyphosis from the PG had a decreased thoracic kyphosis in relaxed standing position, and improved hamstring extensibility as compared with the CG. More than 50% of the participants obtained kyphosis values inside normality, showing an adjusted mean difference between groups in the thoracic curve of about 73% of the baseline mean, resulting in a large improvement and high clinical importance. TRIAL REGISTRATION NUMBER: NCT03831867.

Mandatory after-school use of step tracker apps improves physical activity, body composition and fitness of adolescents.

Previous scientific research on the use of mobile applications to increase physical activity level and improve health among adolescents does not provide conclusive results, one of the main reasons being the lack of adherence to the intervention after the first weeks. For this reason, the main objectives of the research were to determine the changes produced by a compulsory ten-week period of after-school intervention with mobile step-tracking applications on adolescents' health; and the final objective to compare the benefits obtained by each of the mobile applications. To meet the objectives, a longitudinal study with non-probability convenience sampling was proposed. The sample consisted of 400 adolescents from two public compulsory secondary schools in the Region of Murcia, Spain, whose body composition, level of physical activity, adherence to the Mediterranean diet, and physical fitness were measured. The SPSS statistical software was used for statistical analysis. The results showed that adolescents in the experimental group showed a higher level of physical activity and better body composition and physical fitness variables after the intervention compared to the control group, with differences between the different applications used. In conclusion, this research shows the usefulness of mobile applications if they are used in a compulsory way after school hours. The relevance of these results for policymakers lies in the fact that they provide statistical data on the usefulness of mobile applications as an educational resource, being an option to make up for the lack of sufficient physical education teaching hours to meet global physical activity recommendations.

Influence of Physical Activity, Physical Fitness, Age, Biological Maturity and Anthropometric Variables on the Probability of Suffering Lumbar, Neck and Shoulder Pain in Spanish Adolescents from the Region of Murcia.

Background: Back pain in adolescents is a common injury, mainly affecting the lumbar, cervical and sometimes shoulder region. This has been related to various factors, such as lifestyle habits or physical capacity, but no previous research has shown conclusive results. The aims of this study was to analyze the risk of suffering lumbar, neck and shoulder pain according to anthropometric and physical fitness variables, physical activity level, age and biological maturity in adolescents, as well as the influence of sex in the study results. Methods: A descriptive cross-sectional study was performed, including a sample of 2015 adolescents (boys: n = 1006, mean age = 14.41 ± 1.35 years-old; girls: n = 1009, mean age = 14.48 ± 1.41 years-old). The participants underwent an anthropometric evaluation and physical fitness tests were carried out, including a 20 m shuttle run, a counter movement jump, a horizontal jump, a 20 m sprint and push-up tests, followed by the completion of lumbar, neck and shoulder pain questionnaires. Results: Higher values in age and peak height velocity (PHV) showed an increase in the risk of suffering lumbar, neck and shoulder pain (OR = 0.79-1.55; p = 0.000-0.025). The anthropometric variables related to adiposity showed an increase in the risk of suffering back pain, with significant incidence in the lumbar region (OR = 1.32-1.60; p = 0.000); while muscle mass showed a protective effect (OR = 0.59; p = 0.000). Regarding the fitness tests, a better physical fitness seemed to protect adolescents from suffering from the analyzed back pains in the general sample and in the boys sample (OR = 0.56-1.60; p = 0.000), while in the girls sample the influence of the physical fitness was less relevant. Conclusions: Both anthropometry and physical fitness may influence the occurrence of back pain in adolescents, with some variations in their importance according to sex.

Agreement and differences between the equations for estimating muscle and bone mass using the anthropometric method in recreational strength trainees.

Introduction: The interest in estimating muscle mass (MM) and bone mass (BM) has grown in the sporting arena, and more specifically in recreational strength trainees, leading to the creation of different strategies to assess them. The aims were: 1) to investigate the agreement between different MM and BM formulas, and the muscle-bone index (MBI), and to establish the differences between them, in a healthy young adult population; and 2) to analyze if there are differences between males and females in the comparison of MM, BM and MBI formulas. Methods: This study followed a descriptive cross-sectional design. A total of 130 adult active recreational strength trainees were evaluated according to the procedures described by the International Society for the Advancement in Kinanthropometry (ISAK). Estimations were made in kilograms of MM and BM by following the equations by different authors. Results: The results showed significant differences between the values obtained by all the MM and BM formulas in the general sample (p < 0.001), and by the majority of formulas for male and female samples. In the general sample, Lin's coefficient indicated a strong agreement between Kerr, Lee, and Poortmans' MM estimation equations (concordance correlation coefficient (CCC) = 0.96-0.97). However, when stratifying by sex, this agreement persisted only in males (CCC = 0.90-0.94), in contrast with a lack of agreement observed in females (CCC < 0.90). Discrepancies in bone mass agreement were noted both in the general sample (CCC < 0.15) and when stratified by sex (CCC < 0.12). Conclusions: In general, differences were found between the values reported by the MM and BM formulas in recreational strength trainees, without an agreement between them. Sex was shown to significantly influence the differences found. The practical implications are that when comparing an individual with reference tables, other studies, or if analyzing an individual's evolution, the same estimation equation should be used, as they are not interchangeable.

Assessing skeletal muscle mass and lean body mass: an analysis of the agreement among dual X-ray absorptiometry, anthropometry, and bioelectrical impedance.

Introduction: Methods of body composition estimation such as dual-energy X-ray absorptiometry (DXA), anthropometry, and bioimpedance (BIA) are used for the estimation of skeletal muscle mass (SMM) and lean body mass (LBM). No previous studies have examined whether these methods generate comparable results, or whether they are valid by using DXA as the reference. The aims of the present investigation were: (a) to assess the differences between DXA, anthropometry, and BIA in the estimation of SMM and LBM, taking into consideration the impact of sex and hydration status; and (b) to examine the agreement of anthropometry and BIA as compared to DXA for the estimation of SMM and LBM. Methods: A descriptive cross-sectional design was followed with 262 healthy young adults (159 males and 103 females). LBM and SMM were assessed by anthropometry with the formulas from Lee et al. and Kulkarni et al. for LBM; and Kerr (opt a), Kerr (opt b), Lee et al., Poortmans, Matiegka, Martin et al., Drinkwater and Ross, and Heymsfield et al. for SMM; by BIA with the formula reported by the TANITA MC-780-MA software for LBM and SMM; and DXA with the formula reported by the Hologic Horizon software for LBM, and the conversion by Kim et al. for SMM. Results: Significant differences were found for both SMM and LBM in kg, and percentages between most methods and formulas for the overall sample (p < 0.001-0.003) and divided by sex (p < 0.001-0.035). Hydration status did not have a significant effect on the differences between methods and formulas (p = 0.058-0.870). Lin's coefficient revealed limited agreement among the majority of formulas and methods (CCC = 0.007-0.880). The Bland-Altman analysis showed significant differences in most methods and formulas, both in the overall sample and divided by sex, when using SMM and LBM with DXA as the reference (p < 0.001-0.030). Conclusion: There is a lack of agreement between methods and formulas for assessing SMM and LBM. Sex was found to be a significant factor in this analysis. Furthermore, significant differences were observed between most formulas and methods as compared to DXA, except for the equations to estimate SMM with anthropometry by Poortmans.

Validity and agreement between dual-energy X-ray absorptiometry, anthropometry and bioelectrical impedance in the estimation of fat mass in young adults.

Introduction: Assessment of fat mass has historically employed various methods like Dual-energy X-ray Absorptiometry (DXA), and bioelectrical impedance (BIA), and anthropometry with its set of formulas. However, doubts persist regarding their validity and interchangeability to evaluate fat mass. This research aimed to determine the validity of anthropometry, and BIA in estimating fat mass Vs DXA, considering the influence of sex and hydration status. Methods: A descriptive, cross-sectional study included 265 young adults (161 males and 104 females), assessed through DXA, BIA in a standing position, and anthropometry. A fat mass estimation formula with DXA, a fat mass estimation formula with BIA and 10 fat mass estimation formulas with anthropometry were calculated. Results: Significant differences were found across DXA, BIA and anthropometry in both kilograms and percentages for the overall sample (p<0.001), and when the covariable sex was included (p<0.001), with no significant effect of hydration status (p=0.332-0.527). Bonferroni-adjusted analyses revealed significant differences from DXA with anthropometry and BIA in most cases for the overall sample (p<0.001), as well as when stratified by sex (p<0.001-0.016). Lin's coefficient indicated poor agreement between most of the formulas and methods both in percentage and kilograms of fat mass (CCC=0.135-0.892). In the Bland-Altman analysis, using the DXA fat mass values as a reference, lack of agreement was found in the general sample (p<0.001-0.007), except for Carter's formula in kilograms (p=0.136) and percentage (p=0.929) and Forsyth for percentage (p=0.365). When separating the sample by sex, lack of agreement was found in males for all methods when compared with both percentage and kilograms calculated by DXA (p<0.001). In the female sample, all methods and formulas showed lack of agreement (p<0.001-0.020), except for Evans's in percentage (p=0.058). Conclusion: The formulas for fat mass assessment with anthropometry and BIA may not be valid with respect to the values reported with DXA, with the exception of Carter's anthropometry formula for general sample and Evans's anthropometry formula for female sample. BIA could also be an alternative if what is needed is to assess fat mass in women as a group.

Gender equity in sport from the perspective of European women athletes and sport managers, physical education teachers and sport coaches.

Introduction: For years, gender inequality has conditioned women's participation in sport, exposing them to difficult situations and numerous barriers to face. However, no previous research has analyzed the situation of women in sport from the perspective of the athletes themselves, or from the perspective of the coaches, teachers or managers who work with them. Methods: This study examines the perspectives of European women athletes, sports managers, physical education teachers, and sports coaches, on gender equity in sports across six European countries: Greece, Ireland, Italy, Portugal, Spain, and Turkey. The research design was consistent with a critical realist epistemology, and the sampling method was non-probabilistic by convenience. A total of 42 female athletes (mean age: 24.37 ± 8.27 years old; mean sport experience: 6.67 ± 7.76 years) and 45 sports managers, physical education teachers or coaches (mean age: 47.00 ± 11.99 years old; mean sport experience: 9.62 ± 10.60 years), participated in six focus groups in the same countries, in groups of 6 to 10 participants per focus group. Focus groups were conducted to stimulate collective discussions, build upon and question ideas, and reach a consensus on questions drawn up by a group of experts, following previous methodologies. The data analysis involved transcribing, translating, and contextualizing the focus group recordings into English. Inductive thematic analysis, reflexive thematic analysis, and codes and themes within the data were created using NVivo 12 Pro. Results: The main topics discussed by the female athletes were "gender inequality in general and in sport," "barriers to gender equity," "reasons for abandonment," "needs," "environment role models" and "tools for the gender equity in sport." The main topics discussed by the sports managers, physical education teachers, and coaches were "gender inequality in general," "gender inequality in sports," "tools" and "reasons, motives, drivers." The results of the study revealed that gender inequality in sports is influenced by a broader social context, where stereotypes, biases, and discrimination persist. The participants also highlighted the challenges, barriers, and needs that women athletes face in their careers, such as a lack of resources, support, visibility, and recognition. Moreover, the participants suggested some strategies to promote gender equity in sports, such as increasing investment, awareness, and education, creating policies and legislation, fostering women's leadership and role modeling, and developing mixed and inclusive sports projects. Discussion: According to athletes and sports managers/teachers/coaches, gender inequality is still present in sport. There are barriers and challenges that need to be addressed such as lack of resources, visibility, and recognition for female athletes. Among the strategies that can be used to reverse this situation are increasing investment, awareness, and education, creating policies and legislation, fostering women's leadership, and developing mixed and inclusive sport projects.

Relación entre práctica de actividad física en el tiempo libre y rendimiento académico en alumnos(as) de 5° de Primaria a 4° de ESO.

Los objetivos del presente estudio fueron establecer la relación de la práctica de ejercicio físico en el tiempo libre con la práctica de los padres, el rendimiento académico, la importancia que le dan a la asignatura de educación física (EF) y la influencia que consideran que tiene sobre su rendimiento académico; así como sobre la percepción que tienen de la importancia que le dan los padres a la EF. Para ello, un total de 867 niños y niñas de 5° de Primaria a 4° de la ESO (edad: 12.99 ± 1.90 años) diligenciaron un cuestionario previamente validado. El análisis estadístico mostró diferencias significativas al relacionar práctica deportiva de los alumnos con la práctica de sus padres y madres (p < 0.001), así como un mayor rendimiento académico entre los practicantes (p entre 0.008 y <0.001). En general, los alumnos le dieron la misma importancia a la EF que al resto de asignaturas, si bien los practicantes tenían una mejor percepción de la importancia de la EF (p = 0.002). En conclusión, hay una relación entre la práctica de ejercicio físico y el rendimiento académico, con la práctica de los padres y con la importancia que le dan ellos a la asignatura de EF, pero no con la que perciben que le dan sus padres.

The Degree of Problematic Technology Use Negatively Affects Physical Activity Level, Adherence to Mediterranean Diet and Psychological State of Adolescents.

The previous scientific literature has shown how detrimental addictive internet and mobile phone use can be for the adolescent population. However, little is known about their influence on the physical activity, kinanthropometry and body composition, nutrition patterns, psychological state, and physical fitness of this population. For this reason, the objectives of this research were (a) to determine the differences in the physical activity level, kinanthropometric and body composition variables, adherence to Mediterranean diet (AMD), psychological state, and physical fitness according to gender and different levels of problematic use of the internet and mobile phones; and (b) to establish the differences in the physical activity level, kinanthropometric and body composition variables, AMD, psychological state, and physical fitness among adolescents when considering problematic use of the internet and mobile phones in combination. The sample consisted of 791 adolescent males and females between 12 and 16 years of age (1st to 4th course) from four compulsory secondary schools (404 males and 387 females; mean age: 14.39 ± 1.26 years-old; mean height: 163.47 ± 8.94 cm; mean body mass: 57.32 ± 13.35 kg; mean BMI: 21.36 ± 3.96 kg/m2). The physical activity level (baseline score: 2.64 ± 0.67), kinanthropometric variables and body composition, AMD (baseline score: 6.48 ± 2.48), psychological state (baseline life satisfaction: 17.73 ± 4.83; competence: 26.48 ± 7.54; autonomy: 25.37 ± 6.73; relatedness: 24.45 ± 6.54), and physical condition variables were measured. The results showed that adolescent males and females with problematic internet and/or mobile phone use presented a worse psychological state, but it is especially relevant to highlight that females also had a lower level of physical activity and AMD, with problematic mobile phone use being especially relevant, mainly in the psychological state of adolescents. In conclusion, problematic use of the internet and mobile phones can have detrimental effects on the level of physical activity, AMD, and psychological state of adolescents, with the differences found in females being particularly relevant.

What Variables Allow the Differentiation between More and Less Successful Adolescent Volleyball Players?

Kinanthropometric and physical fitness variables have been habitually used for the detection of sports talent in adolescent populations. Considering these variables, players who obtained better scores than their peers in kinanthropometric and physical fitness variables have been traditionally selected for promotion in their teams, without taking into account the possible effect of the maturation process. The aim of the present study was to analyse the differences between adolescent volleyball players in terms of success assessment and the age category, as well as to identify variables that may predict success in volleyball. A total of 101 volleyball players in the U14 age category (28 boys and 73 girls; age = 13.28 ± 0.49 years) and 99 players in the U16 age category (20 boys and 79 girls; age = 15.24 ± 0.59 years) participated in the study. Significant differences were observed in biological maturation in male groups (p < 0.001-0.041), kinanthropometric variables related to bone structure and muscle mass in male groups (p < 0.001-0.048), in variables related to adipose tissue in the U16 female group (p = 0.012-0.032) and in physical fitness tests related to muscle strength and power (p < 0.001-0.049), indicating that more successful (MS) players showed a more advanced biological maturation process, higher values of kinanthropometric variables related to bone structure and muscle mass, and lower values in variables related to adipose tissue, as well as higher levels of physical fitness. The difference in biological maturation and its relationship with structural and muscular anthropometric variables in boys, and physical fitness tests related to muscle strength and power in both boys and girls, are of great importance in the selection process of sports talent in volleyball. These findings should be considered by clubs and coaches, who could be discarding players who could improve their sports performance in later stages when their maturational development is equalised.

Skinfolds compressibility and digital caliper's time response in skinfold measurement in male and female young adults.

BACKGROUND: The skinfold caliper reading of the skinfold thickness depends on its dynamic compressibility. This has led to the fact that, while it is indicated that skinfold readings should be taken when the reading is stable, there is no consensus on at what second the reading should be taken after the application of the skinfold caliper. The new Lipowise PRO digital skinfold caliper was used to analyze the evolution of skinfold readings under skinfold caliper pressure. The aim of the present investigation were: a) to analyze the evolution of the reading time of individual skinfolds when subjected to skinfold caliper pressure and when the skinfold reading reaches stability; b) to describe the physical behavior of skinfold tissues' time response to skinfold caliper pressure, and to explore differences between sites and subjects' skinfolds compressibility; and c) to analyze the sex differences in both the reading and the evolution of the skinfold over time. METHODS: A descriptive cross-sectional design was followed with a convenience sample of 165 healthy young adults (79 males and 86 females), with eight skinfolds measured using the Lipowise PRO skinfold caliper. The Lipowise PRO skinfold caliper uses a programmable reading time allowing for the measurement of the skinfold's thickness at a rate of 100 times per second, and monitoring skinfold behavior over the 3-second measurement period, thereby enabling the assessment of the tissue response to the constant force exerted by the skinfold caliper jaws. RESULTS: All skinfolds showed statistical differences in terms of compressibility characteristics (p < 0.001). Significant differences were found between measurement time points for individual skinfolds and sum of skinfolds (p < 0.001-0.025). Stabilization being found depending on the skinfold measured from 1.5 seconds for biceps, subscapular, iliac crest, supraspinale, abdominal, and thigh skinfolds; 2.0 seconds for ∑6 and ∑8 skinfolds; and 2.5 seconds for triceps and calf skinfolds. It was observed an effect of sex on this issue (p < 0.001-0.030). More specifically, in the case of males, the supraspinale and abdominal skinfolds stabilized after 1.5 seconds; the calf skinfold and ∑6 and ∑8 skinfolds stabilized after 2 seconds; while the rest of the skinfolds did not stabilize until 3 seconds. In the case of females, no stabilization of the triceps skinfold was found, while the rest of the individual skinfolds and the ∑6 and ∑8 skinfolds stabilized from 1.5 seconds. A regression analysis indicated that skinfold thickness could be predicted based on measurement time in 50-77% of the cases (p = 0.001). CONCLUSION: A skinfold caliper application, using the digital caliper Lipowise PRO, of three seconds may be sufficient for achieving stability in the measurement and for obtaining the minimum value for most individual and sum of skinfolds. However, there are certain skinfolds that may require more time when performed on certain individuals, which vary according to sex.

The Effect of Age, Biological Maturation and Birth Quartile in the Kinanthropometric and Physical Fitness Differences between Male and Female Adolescent Volleyball Players.

BACKGROUND: Differences in kinanthropometric and physical fitness performance between boys and girls usually start during adolescence, as a result of the changes in the hormonal environment that occur with the advance of age and biological maturation; Methods: A total of 96 1st Regional Division players adolescent volleyball players, 48 males, (age = 14.17 ± 1.00 years-old) and 48 females (age = 14.41 ± 1.21 years-old) underwent a kinanthropometric assessment, were asked to perform different physical fitness test and to complete a questionnaire. Chronological age, maturity offset, age at peak height velocity (APHV), and birth quartile were calculated; Results: Statistical differences were observed between male and female players in the APHV (p < 0.001). Male players showed higher values in the bone and muscle-related variables (p < 0.001-0.040), as well as in the strength and power production-related physical tests (p < 0.001-0.012), while the female showed higher values in the fat-related variables (p = 0.003-0.013), and performed better in the flexibility tests. Age, maturity offset, and birth quartile showed to have statistical influence in the differences found between sex groups; Conclusions: There is a clear influence of age and biological maturation on the differences found between sexes in adolescent volleyball players that could be taken into account regarding grouping in early stages.

Influence of biological maturation status on selected anthropometric and physical fitness variables in adolescent male volleyball players.

Background: The identification of sport talent among adolescent athletes is a topic that in recent years has been a major focus of interest for both the scientific community and sport managers. Both anthropometry and physical performance through fitness tests have demonstrated to be key elements. Biological maturation, due to its influence on anthropometric variables and physical fitness, has also been studied in relation to sport talent identification. Objective: To analyse differences according to biological maturation status in anthropometric characteristics and performance in physical fitness tests, and to determine which variables predict better performance in physical fitness tests in adolescent volleyball players. Methods: A cross-sectional design was followed to collect the data. A total of 48 male sub-elite volleyball players (14.17 ± 0.73 years) completed a socio-demographic and sports ad hoc questionnaire. Anthropometric variables were measured following the guidelines of the International Society for the Advancement in Kinanthropometry (ISAK) including four basic measurements (body mass, height, sitting height and arm span); eight skinfolds (triceps, biceps, subscapular, iliac crest, supraspinale, abdominal, thigh and calf); four girths (arm relaxed, flexed and tensed arm, middle thigh and calf); five breadths (biacromial, biileocrestal, humerus, femur and bi-styloid); three lengths (acromiale-radiale, radiale-stylion and stylion-medio dactilion); and a height (ilioespinale). Physical fitness was assessed, including the sit-and-reach, back scratch, long jump, medicine ball throw, counter movement jump (CMJ), 20 meters sprint, and agility tests. Furthermore, maturity offset and age at peak height velocity (APHV) was calculated. Results: Significant differences were found in the body mass (Mean Difference, MD = 20.86-30.75), height (MD = 11.72-19.09), sitting height (MD = 4.27-10.27), arm span (MD = 12.91-20.78), body mass index (MD = 3.72-5.63), upper limb length (MD = 7.76), corrected muscle girths (MD = 2.06-9.31), ∑6 and 8 skinfolds (MD = 3.67-50.21) fat mass and percentage (MD = 0.30-11.58), muscle (MD = 4.13-10.64) and bone mass (MD = 1.61-3.54) (p < 0.001-0.030), showing higher values the early maturers. In the physical fitness tests, significant differences were observed in the medicine ball throw (MD = 1.26-2.80) and in CMJ power (MD = 156.71-379.85) (p < 0.001). Regression models identified fat mass percentage predicted worse physical test performance (p < 0.001), while age, maturation offset, muscle and bone variables were predictors of better physical performance (p < 0.001). Conclusions: Significant differences based upon the stages of biological maturation were found in the anthropometric and physical condition variables in favor of the players whose maturation process was more advanced, with the variables related to fat and adipose, muscle and bone development conditioning their performance in the physical condition tests.

Differences between Four Skinfold Calipers in the Assessment of Adipose Tissue in Young Adult Healthy Population.

Background: The aim of this study was to analyze the validity of four different skinfold calipers, as well as to establish the differences between them in a healthy young adult population. Methods: The present study followed a cross-sectional design, including 138 participants, with 69 males (21.46 ± 2.52 years) and 69 females (22.19 ± 2.85 years). The measurement protocol included basic measurements of body mass and stretch stature and eight skinfolds with a Harpenden, Holtain, Slim Guide, and Lipowise. The ∑6 and ∑8 skinfolds and fat mass were calculated. The order in which the skinfold calipers were used was randomized. Results: No significant differences were found in either the Σ6 and Σ8 skinfolds or masses and fat percentages calculated with the skinfolds obtained with the different calipers (p > 0.05), and the inclusion of the covariates of sex, BMI, and hydration status of the participants showed no effect on the differences. The Bland−Altman test showed significant differences between the calipers (p < 0.001). Conclusion: It has been observed that the analyzed calipers have shown validity for the assessment of adiposity-related variables in a male and female sample of non-overweight, young healthy adults, but they are not interchangeable with each other when the assessment is meant to be compared over time or with other samples.

Relationship between Biological Maturation, Physical Fitness, and Kinanthropometric Variables of Young Athletes: A Systematic Review and Meta-Analysis.

There is a growing interest in knowing the relationship between biological maturation and sport performance-related variables of young athletes. The objective of this study is to analyze the relationship between biological maturation, physical fitness, and kinanthropometric variables of athletes during their growing period, according to their sex. The systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statement and the search protocol was registered in PROSPERO, code: CRD42020208397. A search through the PubMed, Web of Sciences, and EBSCO databases was performed. A total of 423 studies were screened and 13 were included in the meta-analysis. The meta-analysis was completed by using the mean and standard deviation of each variable according to each maturation status (early, on time, or late). Differences depending on maturation were found on physical fitness, with better results in the advanced maturational groups in the male population (standard mean difference (SMD) = 0.17-2.31; p < 0.001-0.05). Differences depending on maturation were found for kinanthropometric variables in males (SMD = 0.37-2.31; p < 0.001-0.002) and height and body mass in females (SMD = 0.96-1.19; p < 0.001). In conclusion, the early maturation group showed higher values in kinanthropometric variables and better results in physical fitness, highlighting the importance of the maturational process in the talent selection programs. Despite that, more research is needed to clarify the relationship of maturation with the other variables on female populations and the changes in the muscle and bone variables during the maturation processes of both sexes.

Effect of an injury prevention program on the lower limb stability in young volleyball players.

BACKGROUND: Volleyball players have a high risk of injury in the lower limbs as a consequence of the specific characteristics of the sport, such as repetitive jumps and falls. The objective of the present study was to evaluate the effects of a multidisciplinary injury prevention program on lower limb stability in young volleyball players. METHODS: The experimental design was a non-randomized controlled trial. All the measurements were performed in a standardized room in a sports center. Twenty-six young male volleyball players (mean age: 15.39±1.16 years), divided into experimental (N.=15) and control groups (N.=11) participated in this study. The experimental group performed an 8-week prevention program including lower limb strength and plyometric training, and joint and core stability. The Y-Balance and force platform landing tests were carried out as the pre- and post-tests. RESULTS: The main outcome measures were the injuries history, distance and difference reached in anterior, post-lateral and post-medial axis of the Y-Balance test, and the force produced on the z, x, and y axis after landing. Differences were found between groups and measurements in all the variables of the Y-Balance test, except in the frontal axis for the dominant leg and for the differences between legs (P=0.039-0.001); and in the ground reaction forces (z axis) (P=0.040), the x axis (P=0.014) and the dynamic postural stability index (P=0.025) of the lateral jump with the non-dominant leg. CONCLUSIONS: An 8-week prevention program seems to improve the lower limb stability in young volleyball players.

Differences in Fat Mass Estimation Formulas in Physically Active Adult Population and Relationship with Sums of Skinfolds.

Changes in body composition and specifically fat mass, has traditionally been used as a way to monitor the changes produced by nutrition and training. The objective of the present study was to analyse the differences between the formulas used to estimate fat mass and to establish the existing relationship with the body mass index and sums of skinfolds measurement in kinanthropometry. A total of 2458 active adults participated in the study. Body mass index (BMI) and skinfolds were measured, and the Kerr, Durnin-Womersley, Faulkner and Carter equations were used to assess fat mass. Significant differences were found between all the formulas for the percentage of fat mass, ranging from 10.70 ± 2.48 to 28.43 ± 5.99% (p < 0.001) and fat mass from 7.56 ± 2.13 to 19.89 ± 4.24 kg (p < 0.001). The correlations among sums of skinfolds and the different equations were positive, high and significant in all the cases (r from 0.705 to 0.926 p < 0.001), unlike in the case of BMI, were the correlation was lower and both positive or negative (r from -0.271 to 0.719; p < 0.001). In conclusion, there were differences between all the formulas used to estimate fat mass; thus, for the evaluation of fat mass with kinanthropometry of an active adult, the use of the same formula is recommended on all occasions when the results are going to be compared or when an athlete is compared with a reference.

Back Pain Related with Age, Anthropometric Variables, Sagittal Spinal Curvatures, Hamstring Extensibility, Physical Activity and Health Related Quality of Life in Male and Female High School Students.

Spinal pain (SP) is widely extended among adolescents. The origin of SP can be multifactorial; thus, the present study aimed to estimate the prevalence and risk of SP in high school students and to determine the differences in sagittal spinal curvatures and pelvic tilt, hamstring extensibility, age, anthropometric variables and healthy lifestyle habits dependent on SP between sexes. Two hundred seventy-three teenagers took part in this cross-sectional study. Age, sagittal spinal curvatures, hamstring extensibility, physical activity, sedentary lifestyle, anthropometric variables and health related quality of life (HRQL) were recorded. SP was reported by 16.12% of adolescents. Differences were observed in the HRQL according to SP (p < 0.05). Participants without SP were less sedentary (22.12%) and younger (13.10 years old) than participants with SP (40.91% and 13.66, respectively) (p < 0.05). A logistic regression model showed that both variables were significantly collinear (VIF = 1.01; Durbin-Watson = 2.10). Subjects with low back pain (LBP) had a higher weight, body max index, and hip girth than subjects without pain (p < 0.05). A misalignment in the lumbar spine was associated with LBP for males (Cramer's V = 0.204, p = 0.022). In conclusion, adolescents with SP were older and had a lower HRQL in all dimensions. SP could be predicted according to age and sedentary habits.

Hamstring extensibility differences among elite adolescent and young dancers of different dance styles and non-dancers.

BACKGROUND: Hamstrings have been analyzed extensively due to their tendency to shorten and their effect in the lumbo-pelvic dynamics and the sagittal position of the spine in trunk flexion with extended knees positions. It has been demonstrated that practicing a certain sport results in long-term changes in hamstring extensibility. Despite this, adequate extensibility of the hamstring musculature is essential for the dancer's performance. Several studies have found differences in the extensibility of the hamstrings depending on the dance style, but none have compared ballet, Spanish dance and modern dance. The purpose of the present research was to analyze the differences in hamstring extensibility among professional dance students based on dance style practiced and non-dancers. METHODS: The sample was comprised of 210 students from the Professional Dance Conservatory (70 for ballet, 70 for Spanish dance and 70 for modern dance) and 70 non-dancers. For the assessment of hamstring extensibility, the angle in the passive and active straight leg raise (PSLR and ASLR, respectively) test, and the scores of the pelvic tilt in sit-and-reach (SR) test and the toe-touch (TT) test were randomly conducted. RESULTS: The results showed significant differences for all the tests according to group (p < 0.001). In the PSLR and ASLR test, for both legs, and in the pelvic tilt in the SR test, the ballet dancers showed greater ranges of hamstring extensibility than the modern dancers and Spanish dancers (p ≤ 0.001). In the distance in the SR test and in the pelvic tilt in the TT test, the ballet dancers obtained higher values than the Spanish dancers (p = 0.004 and p = 0.003, respectively). The modern dancers showed higher ranges of hip flexion than the Spanish dancers in the ASLR test for both legs and in the pelvic tilt in the SR test (p from 0.007 to <0.001). Dancers showed significantly higher hamstring extensibility than non-dancers in all the tests (p < 0.001). CONCLUSIONS: The systematic practice of dance, regardless of the style, seems to lead to high ranges of hamstring extensibility. Ballet dancers have the greatest hamstring extensibility.

Relación entre el efecto relativo de la edad en el campeonato de España de golf en categorías Sub16 y el rendimiento deportivo / Relação entre o efeito relativo da idade no campeonato espanhol de golfeU16 e o desempenho desportivo / Relationship between the relative effect of age in the Spanish U16 golf championship and sporting performance

En la presente investigación se plantearon dos objetivos: 1) identificar la proporción de jugadores de golf en edad de formación que se clasificaban para los campeonatos de España en función del año y del trimestre del año de nacimiento tanto para el total de la muestra, como para la muestra dividida por sexos. 2) Analizar el efecto de la edad relativa sobre el rendimiento de los jugadores y las jugadoras de golf en el campeonato de España en las diferentes categorías para el total de la muestra, como para la muestra dividida por sexos. Se incluyeron un total de 794 jugadores de golf, (511 varones, media de edad: 13,91±2,08 años; y 283 mujeres, media de edad: 14,29±1,89 años). De cada participante se obtuvo la siguiente información: año de nacimiento, mes de nacimiento, inscripción y participación en el Campeonato de España de golf, posición obtenida en el campeonato. Se observaron diferencias significativas en cuanto a la asistencia al Campeonato de España en función del año de nacimiento (χ2=22,92; p=0,001) y en función del cuartil de nacimiento (χ2=57,59; p=0,001) al analizar el conjunto de los participantes. El análisis de regresión mostró que el puesto en el Campeonato de España puede ser un factor predicho por el año de nacimiento en un porcentaje entre el 7 % y el 15% de los casos (p<0,001-0,009). En base a estos resultados, sería necesario replantear el sistema de competición de los campeonatos nacionales de golf en edades en formación para garantizar una competición en igualdad de condiciones. (AU)

The present study had two objectives: 1) to identify the proportion of junior golfers qualifying for the Spanish Championships as a function of year and quarter ofthe year of birth for the total sample, as well as for the sample divided by sexes. 2) To analyse the effect of relative age on the performance of golf players at the Spanish Championships in the different categories for the total sample, as well as for the sample divided by sexes. A total of 794 golf players were included (511 males, mean age: 13.91±2.08 years; and 283 females, mean age: 14.29±1.89 years). The following information was obtained for each participant: year of birth, month of birth, participation in the Spanish Golf Championship, position obtained in the championship. Significant differences in attendance at the Spanish Championship were observed according to year of birth (χ2=22.92; p=0.001) and according to quartile of birth (χ2=57.59; p=0.001) when analysing the participants as a whole. The regression analysis showed that the place in the Spanish Championships can be a predictorof year of birth in a percentage between 7 % and 15 % of the cases (p<0.001-0.009). Based on these results, it would be necessary to rethink the competition system of the national golf championships to ensure a level playing field. (AU)

A presente investigação tinha dois objectivos: 1) identificar a proporção de jovens golfistas qualificados para o Campeonato de Espanha em função do ano e do trimestre do ano de nascimento para a amostra total, bem como para a amostra dividida por sexo. 2) Analisar o efeito da idade relativa no desempenho dos jogadores de golfe nos campeonatos espanhóis nas diferentes categorias para a amostra total, bem como para a amostra dividida por sexo. Foi incluído um total de 794 jogadores de golfe (511 homens, idade média: 13,91±2,08 anos; e 283 mulheres, idade média: 14,29±1,89 anos). Foram obtidas as seguintes informações para cada participante: ano de nascimento, mês de nascimento,inscrição e participação no Campeonato Espanhol de Golfe, posição obtida no campeonato. Foram observadas diferenças significativas naparticipação no Campeonato de Espanha de acordo com o ano de nascimento (χ2=22,92; p=0,001) e de acordo com o quartil de nascimento (χ2=57,59; p=0,001) ao analisar os participantes como um todo. A análise de regressão mostrou que o lugar no Campeonato de Espanha pode ser um preditor do ano de nascimento numa percentagem entre 7% e 15% dos casos (p<0,001-0,009). Com base nestes resultados, seria necessário repensar o sistema de competição dos campeonatos nacionais de golfe em júnior para assegurar um campo de jogo nivelado. (AU)