Biological maturation assessment methods in adolescent soccer players considering zinc status / Métodos de evaluación de la maduración biológica en jugadores adolescentes de fútbol considerando el estado de zinc

SUMMARY: The purpose of this study was to compare different methods of maturity evaluation and their relation with performance-related physical and anthropometric variables in young soccer players, with different plasma zinc status. A total of 53 healthy male young soccer players (age: 13±1 years; body mass: 48±10 kg; stature: 160±10 cm) participated in this study. Variables from physical fitness (stature, ST; fat-free mass, FFM; handgrip strength in the dominant hand, DHS), testosterone and zinc plasma concentration were measured. Biological maturity was evaluated by sexual maturity (development of: pubic hair, PH; genitals, GD; axillary hair; AH), bone maturity (TW3 method; BA), and testosterone plasma concentration methods. We observed that: (i) the frequency of hypozincemics and normozincemics children stratified by BA-CA, PH and GD were similar in each category; (ii) the BA allowed the identification of differences between the three categories, in at least two performance-related variables (FFM and DHS, p<0.0001); (iii) the AH method was able to discriminate only for DHS (p<0.0001); and (iv) the testosterone method was not able to identify differences between the four maturation categories with regard to ST, FFM, and DHS. Results suggested that Zinc deficiency did not influence the results obtained for the maturation categories defined by the different assessment methods. The assessment of biological maturation by BA seems to be the most effective for the stratification of performance-related and anthropometric variables in young soccer players. Nevertheless, the AH method should also be considered as a fair option to be used in field studies and practice.

RESUMEN: El objetivo de este estudio fue comparar diferentes métodos de evaluación de madurez y su relación con variables físicas y antropométricas relacionadas con el desempeño en jóvenes jugadores de fútbol, con diferentes niveles plasmáticos de zinc. Participaron en este estudio 53 jugadores de fútbol jóvenes sanos (edad: 13 ± 1 años, masa corporal: 48 ± 10 kg, estatura: 160 ± 10 cm). Se midieron las variables de la aptitud física (estatura, ST, masa libre de grasa, FFM, fuerza de agarre en la mano dominante, DHS), testosterona y concentración plasmática de zinc. Se evaluaron la madurez sexual (desarrollo de vello púbico, PH, genitales, DG, cabello axilar, AH), madurez ósea (método TW3, BA) y concentración plasmática de testosterona. Se observó que: (i) la frecuencia de los niños hipoxincémicos y normozincémicos estratificados por BA-CA, PH y GD fueron similares en cada categoría; (ii) el BA permitió la identificación de diferencias entre las tres categorías, en al menos dos variables relacionadas con el desempeño (FFM y DHS, p <0,0001); (iii) el método AH fue capaz de discriminar sólo para DHS (p <0,0001); y (iv) el método de testosterona no fue capaz de identificar diferencias entre las cuatro categorías de maduración con respecto a ST, FFM y DHS. Los resultados sugirieron que la deficiencia de zinc no influyó en los resultados obtenidos para las categorías de maduración definidas por los diferentes métodos de evaluación. La evaluación de la maduración biológica por BA parece ser la más efectiva para la estratificación de variables de rendimiento y antropométricas en jóvenes jugadores de fútbol. Sin embargo, el método AH también debe ser considerado como una opción justa para ser utilizado en estudios de campo y práctica.

Methodological agreement between body-composition methods in young soccer players stratified by zinc plasma levels / Acuerdo metodológico entre los métodos de composición corporal en jugadores jóvenes de fútbol estratificados por los niveles plasmáticos de zinc

It is feasible to think that the body composition assessment may be influenced by maturational and zinc status, especially in young athletes, which perform regularly high volume of physical training. In accordance, it seems important to clarify the impact of these factors in body composition assessment in athletes, since errors may lead to mistakes in training prescription and diet elaboration, and therefore affect the athletic performance. The objective was to compare (1) different methods of body composition evaluation in young soccer players stratified by zinc plasma levels; and (2) the two reference methods using skinfolds thickness in children (Slaughter's and Lohman's equations), considering the maturation level. In this cross-sectional study, fifty tree young soccer players (13.3±0.7 y) were submitted to blood collection, electric bioimpedance (BIA), dual energy X-ray absorptiometry (DXA), anthropometric measures (body mass, stature and skinfolds thickness (ST)) and hand-wrist X-ray. Body composition evaluation was performed by: DXA, ST (Lohman and Slaughter equations) and BIA (Houtkooper equation) methods. Zinc status provided two groups: Normozincemic and Hypozincemic athletes, determined by cut-off point of 11.0 µmol/L. Significant difference on descriptive data for all participants after zinc status stratification was observed only for plasma zinc concentration; (2) Significant correlations were observed between the assessment methods (fat percentage: r= 0.34 to 0.98 and p<0.001 to 0.013; fat free mass: r= 0.95 to 0.9998 and p<0.001), and lowers correlations were observed when electric impedance was involved; and (3) Bland-Altman plots across methods showed a closer agreement when DXA and ST were compared. In conclusion (1) The ST method was better than BIA to assess the body composition (in young soccer players) when DXA scans are not available; (2) The comparison of models based on ST showed that the best association with the values from DXA were obtained for the Slaughter equation, followed by the Lohman equation using bone age instead of chronological age; and (3) Plasma zinc levels seem not to influence the body composition assessment, which certainly warrants further studies.

Es factible pensar que la evaluación de la composición corporal puede estar influenciada por el estado de maduración y los niveles plasmáticos de zinc, especialmente en atletas jóvenes, que regularmente realizan un alto volumen de entrenamiento físico. Por tanto, es importante aclarar el impacto de estos factores en la evaluación de la composición corporal de los atletas, ya que errores en su análisis pueden conducir al desarrollo de una equivocada prescripción de entrenamiento, además de una dieta determinada, y por lo tanto afectar el rendimiento deportivo. El objetivo de esta investigación consistió en: (1) comparar los diferentes métodos de evaluación de la composición corporal en futbolistas jóvenes estratificados por los niveles plasmáticos de zinc; (2) comparar los dos métodos de referencia utilizando el espesor de los pliegues cutáneos en niños (ecuaciones de Slaughter y Lohman), teniendo en cuenta el nivel de maduración. En este estudio transversal, cincuenta futbolistas jóvenes (13,3±0,7 años) fueron sometidos a un perfil bioquímico de sangre, bioimpedancia eléctrica (BIA), absorciometría de rayos X de energía dual (DXA), medidas antropométricas (masa corporal, estatura y pliegues cutáneos de espesor (ST)) y radiografía de mano-muñeca. La evaluación de la composición corporal se realizó por: DXA, ST (ecuaciones Lohman y Slaughter) y BIA (ecuación Houtkooper). El nivel de zinc identificó dos grupos: deportistas normozincémicos e hipozincémicos, determinados por un punto de corte de 11,0 mmol/L. Se observó una diferencia significativa en los datos descriptivos de todos los participantes después de la estratificación del estado de zinc sólo para la concentración de zinc en plasma; se observaron correlaciones significativas entre los métodos de evaluación (porcentaje de grasa: r= 0,34 a 0,98 y p <0,001 a 0,013; masa libre de grasa: r= desde 0,95 hasta 0,9998 y p <0,001), y disminuyeron las correlaciones al estar involucrada la impedancia eléctrica. Los resultados a través de los métodos Bland y Altman mostraron un acuerdo más cercano al comparar DXA y ST. El método ST fue mejor que el BIA para evaluar la composición corporal (en los jugadores jóvenes de fútbol), cuando no estaban disponibles los escaneos DXA. La comparación de los modelos basados en ST mostró que la mejor asociación de valores DXA se obtuvieron para la ecuación Slaughter, seguidos por la ecuación Lohman utilizando la edad ósea en lugar de la edad cronológica. Los niveles de zinc en plasma parecen no influir en la evaluación de la composición corporal, lo que amerita más estudios.

Análise do conhecimento de profissionais de Educação Física referente à prescrição de exercícios físicos para portadores de condromalácia patelar / Knowledge analysis of physical education professionals regarding exercise prescription for patients with chondromalacia patellae

Este trabalho buscou verificar a conduta profissional que professores de Educação Física (PEFs) possui na utilização do exercício de extensão de joelhos na cadeira extensora e no leg press em pessoas sofrendo de condromalácia da patela. Dois experimentos foram feitos, utilizando questionários aplicados em academias do Rio de Janeiro. O primeiro estudo foi dividido nas seguintes opções: “cadeira extensora”, “leg press”, “ambos” e “nenhum” e foi aplicado em 18 PEFs. O segundo estudo foi relacionado com a utilização de ângulos específicos na máquina de extensão de pernas que foi dividido em: “0°-30°”, “60°-90°”, “ambos” e “nenhum” que foi aplicado em 24 PEFs. Adicionalmente ambos os questionários possuíam seções específicas onde informação complementar poderia ser escrita para justificar as respostas. As justificativas foram nomeadas (JT+) quando satisfatória e (JT-) na ausência de argumentos baseados em dados científicos. A análise estatística foi feita com o teste qui-quadrado e a significância foi considerada quando o valor de p era menor do que 0,05. No primeiro estudo nós observamos que a utilização do leg press foi menor do que as outras opções. Além disso, o percentual de JT+ foi maior nas opções “cadeira extensora”, “leg press” e “nenhum”. No segundo estudo nós observamos que o percentual de PEFs que escolheram a opção “0°-30°” foi maior em relação a opção “ambos”. Quando as justificativas foram analisadas, nós observamos que todas as opções tiveram um maior percentual de JT-, com exceção da opção “ambos” que não mostrou diferenças (p>0,05). Nós concluímos que os PEFs possuem uma adequada conduta quando escolhem os exercícios para pessoas com condromalácia patelar, porém existe uma necessidade de melhor sustentar as argumentações relacionadas com a utilização de ângulos no exercício de cadeira extensora.

This work aimed to verify which professional conduct Physical Education teachers (PETs) have when using knee extension exercise with leg extension machines and leg presses in people suffering from chondromalacia patellae. Two experiments were done using questionnaires applied in Rio de Janeiro gyms. The first study was divided in the following options: “leg extension”, “leg presses”, “both” or “none” and was applied in 18 PETs. The second study was related to the utilization of specific angles in leg extension machines that were divided in: “0°-30°”, “60°-90°”, “both” and “none” that was applied to 24 PETs. Additionally both questionnaires have specific sections where complementary information could be written to justify the answers. The explanations was named (JT+) when satisfactory and (JT-) in the absence of arguments based in scientific data. Statistical analysis was done by chi square test and significance was considered when p value was lower than 0.05. In first study we observed that leg press utilization was lower than the other options. Besides that JT+ percent was higher in options “leg extension”, “leg press” and “none” but had no significant alterations in “both”. In second study we observed that the percent of PETs that chose option “0-30°” was higher in relation to the option “both”. When the explanations were analyzed, we observed that all the options had a higher percentage of JT- with exception of option “both” that showed no differences (p>0.05). We conclude that PETs have an adequate conduct when choosing exercises for people with chondromalacia patellae, however there is a need to better sustain the argumentations relating to angle utilization in leg extension exercises.