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.

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.

Differences in Maturity, Morphological, and Fitness Attributes Between the Better- and Lower-Ranked Male and Female U-14 Portuguese Elite Regional Basketball Teams.

Ramos, S, Volossovitch, A, Ferreira, AP, Barrigas, C, Fragoso, I, and Massuça, L. Differences in maturity, morphological and fitness attributes between the better- and lower-ranked male and female U-14 Portuguese elite regional basketball teams. J Strength Cond Res 34(3): 878-887, 2020-During a national championship, the anthropometric, physiological, and maturation attributes of 13-14-year-old players of regional selection basketball teams and their association with team's final classification were analyzed. Body parameters (body mass, height, skinfolds, and lengths) were measured and physiological capacities assessed by sprint (20 m), agility, jump, and upper-body strength tests. Chronological age, maturity offset (years from age at peak height velocity; YAPHV), and predicted age at peak height velocity were calculated. In both sexes, no significant differences were found for maturity. Anthropometric and physiological analysis indicated that male players from finalist's teams were significantly faster, were more agile, threw the medicine ball longer, and showed lower percentages of body fat than players from lower-ranked teams. Further, semifinalists were faster than lower-ranked players. In the same sense, female players from semifinalist teams demonstrated to be significantly faster, more agile, and threw the medicine ball longer than female players from lower-ranked teams. In addition, discriminant analysis showed that speed (in boys) and the combination of speed and upper limb strength (in girls) could successfully discriminate players with different performances in a championship. In conclusion, speed and upper limb strength appear to be the physical attributes associated with better team performance in youth basketball. Coaches should be aware of the relationship between the improvement of these physical attributes and the teaching-learning process of the basketball game.

Comparación de tres metodologías para estimar el porcentaje de estatura adulta en niños y niñas de 7 a 16 años / Comparison of three methodologies for estimating percentage of adult height in children from 7 to 16 years

El porcentaje de estatura adulta (PEA) es un indicador del estado de maduración, que refleja la variación en la tasa y progreso de crecimiento. Existen diversos métodos para estimar la estatura adulta, sin haberse documentado en la literatura de manera concreta sus similitudes o diferencias. Los objetivos del presente trabajo fueron comparar tres métodos de estimación del PEA, identificar cambios seculares en niños y adolescentes y establecer valores de referencia del PEA para población portuguesa. Se midieron en 799 niños y 736 niñas, de 7,0 a 16,49 años, la edad ósea, el peso y la estatura, para estimar el porcentaje de estatura adulta por las metodologías TW3, KR y RWT. Los valores del método TW3 del presente estudio, fueron comparados con los reportados en décadas atrás para identificar cambios seculares. Se utilizó un ANOVA de medidas repetidas para estimar las diferencias entre los métodos en el presente estudio, así como gráficas de Bland y Altman. Se utilizó la prueba de Kruskal-Wallis para analizar las diferencias entre los valores encontrados en la presente investigación y los presentados en décadas atrás en otros estudios. No se encontraron diferencias entre los métodos TW3 y KR en los diferentes grupos de edad cuando se clasificaron los sujetos por edad cronológica, en ambos sexos (P>0,05). Así mismo, no se observaron cambios seculares en el PEA (P>0.05). Los métodos TW3 y KR pueden ser intercambiables entre sí, debido a que no presentan diferencias en la estimación a diferentes edades y en ambos sexos. Además, no existió cambio secular en la estimación de PEA por estas metodologías, lo que las hace útiles en la actualidad.

The adult height percentage (AHP) is an indicator of maturity state, which reflects variation in growth rate. Several methods estimates adult height; however, its similarities or differences have not been documented in a concrete way in literature. The aims of the present work were to compare three common methods of AHP estimation, to identify children and adolescents secular changes and to develop AHP reference values in Portuguese population. Skeletal age, weight and height were measure in 799 children and 736 girls from 7.0 to 16.5 years; in addition, parents height was self-reported by them to estimate the AHP by TW3, RWT and KR methods. ANOVA was used to estimate differences between TW3, KR and RWT methods, as well as Bland-Altman graphs. Also, Kruskal-Wallis test was applied. No differences were found between TW3 and KR methods in all age groups, in both sexes, when subjects were classified by chronological age (P> 0.05). Likewise, no secular changes were observed in AHP (P> 0.05). Not only TW3 and KR protocols can be interchangeable each other because they did not present differences in the AHP estimation at different ages and in both sexes. However, secular changes were not observed in AHP estimation by these methods.

Health-related quality of life of Portuguese children and adolescents according to their biological maturation and volume of physical activity.

PURPOSE: The purpose of this study was to analyze the relationship between biological maturation and health-related quality of life (HRQoL) in Portuguese children and adolescents of both sexes when the effect of chronological age (CA) and volume of physical activity (VPA) were removed. METHODS: HRQoL, biological maturation, CA, and VPA were assessed in 750 children and adolescents, 11-17 years old, from 3 schools in Lisbon, Portugal. The KIDSCREEN-52 was used to assess HRQoL. Maturity indicator was bone age (BA), using Tanner-Whitehouse III method (TW3). The participants were classified into three different maturity categories: late, on time, and early maturers. VPA was assessed by questionnaire (RAPIL II). An analysis of covariance (ANCOVA), using the CA and the VPA as covariates was completed. The level of significance was set at p ≤ 0.05. RESULTS: Analysis of covariance suggested an influence of biological maturation in physical well-being dimension in both sexes, with early-maturing girls and boys having worst perception. Maturity groups were also influent in moods and emotions for girls. CA seems to be particularly important in self-perception and parent relation and home life for girls and in school environment for boys. CONCLUSION: Biological maturation and CA have relevant impact on some HRQoL dimensions. These variables, due to their nature and effect should be considered particularly when working with specific domains of HRQoL as physical well-being in both sexes, moods and emotions and self-perception and parent relation and home life for girls and in school environment for boys.

Impacto de la maduración y de los puestos específicos en la condición física en jóvenes futbolistas / Influence of maturity and specific playing positions on physical fitness in young soccer players

Objetivo: Describir las características condicionales de una población de deportistas jóvenes, tanto por nivel madurativo como por puestos específicos. Muestra: Se han estudiado 95 jugadores de fútbol (13-16 años) pertenecientes a escuelas deportivas de futbol. Métodos: Las variables utilizadas en este estudio han sido: edad, puesto específico (medio, defesa, delantero, portero), peso, altura, maduración, capacidad aeróbica, fuerza isométrica máxima del tren superior, fuerza máxima, fuerza explosiva y elástico-explosiva del tren inferior, velocidad linear 30m (tiempo), velocidad de cambio de dirección, y agilidad y flexibilidad del tronco. Resultados: Se han encontrado diferencias significativas entre los grupos de maduración retrasado y normal en las variables velocidad linear, fuerza estática, fuerza isométrica máxima derecha y tasa máxima de producción de fuerza. Entre los grupos de maduración retrasado y avanzado se han encontrado los mismos resultados y diferencias significativas en la variable flexibilidad. En la valoración por puestos específicos se han encontrado diferencias significativas en la fuerza estática de los medios y de los delanteros. Conclusiones: a) Los jugadores con maduración avanzada presentan mejores valores condicionales; b) las pruebas condicionales, en estos rangos de edad, no parecen ser determinantes para poder realizar la selección de jugadores; c) se hace necesario incluir entrenamientos específicos para cada puesto, y d) el portero necesita una mayor atención en su entrenamiento(AU)

Objective: To describe the physical fitness of a young athlete population grouped in two categories: maturity and specific positions. Sample: We studied 95 players (13-16 years) belonging to soccer schools. Methods: The variables used in this study were age, the specific position (center, defense, forward, goalkeeper), weight, height, maturity, the aerobic capacity, the maximum isometric strength of the upper arms, the maximum force, the explosive force and elastic-explosive of the lower body, speed in 30m (time), the rate of change of direction and agility and trunk flexibility. Results: Significant differences were found between normal and delayed maturity groups in: linear velocity, static force, maximum isometric force (right) and production of maximum rate of force. The same results and also significant differences in the variable flexibility were observed between delayed and advanced maturity groups. Significant differences were found between specific position (midfielders and forwards) in the static force variable. Conclusions: (i) Advanced players (in maturity) scored better in physical fitness, (ii) the physical fitness evaluation at these ages does not appear to be appropriate to select soccer players, (iii) it seems important to include specific training for each position, (iv) it seems important to give more attention to goalkeeper training(AU)

Caracterización antropométrica y maduración de una población de futbolistas jóvenes portugueses / Characterization of a population of young Portuguese soccer players

Objetivo: Describir las características antropométricas y la maduración de una población de deportistas jóvenes con proyección para llegar a profesionales del fútbol. Muestra: Se han estudiado 108 futbolistas (14-16 años) pertenecientes a las escuelas deportivas del Sporting Clube de Portugal. Métodos: Las variables utilizadas en este estudio han sido el peso, la altura, la predicción de la altura y la altura de sentado, la maduración y el puesto específico. Los futbolistas han sido agrupados por edad y por puestos específicos. Resultados: Se han encontrado diferencias significativas por edades en todas las variables estudiadas, excepto en la predicción de la altura. Por puestos específicos, los medios presentan diferencias significativas en todas las variables con los delanteros; en todas excepto el peso con los defensas; y en estatura con los porteros. Conclusiones: La altura y el peso no son determinantes para el rendimiento pero sí deben ser consideradas para la elección de ciertos puestos específicos(AU)

Objective: To describe the anthropometric and maturity characteristics of a young athlete population who wish to play professional football Sample We studied 108 players (14-16 years) belonging to the schools of Sporting Club of Portugal. Methods: The variables used in this study were weight, height, predicted height and sitting height, maturity and the specific position. The players were grouped by age and by specific positions. Results: We found significant differences by age in all variables except for height prediction. The centers presented significant differences in all variables when compared with the forwards, in all but the weight when compared with the defenders, and in stature when compared with the goalkeepers. Conclusions: Height and weight are not critical for performance, but should be considered for the choice of certain specific positions(AU)

Obesity, academic performance and reasoning ability in Portuguese students between 6 and 12 years old.

Obesity has been linked to several physiological and psycho-social diseases, decreases in cognitive function, poor levels of scholastic achievement, low socioeconomic status and delayed onset of maturity. This study investigates the association between obesity and both academic performance and reasoning ability in 394 male and 398 females students between the ages of 6 and 12 from Lisbon, Portugal. It also assesses how this relationship may be influenced by chronological age, maturity and socioeconomic status. The results suggest that: 1) reasoning ability is independent of socioeconomic status and level of maturity; 2) no differences in reasoning ability exist between groups of different BMI; 3) academic performance is moderated by chronological age in boys, and by maturity in both genders; 4) obesity is not associated with academic performance. It is concluded that reasoning ability and academic performance are not associated with obesity, and that inter-individual differences in academic performance in boys may be explained by differences in their level of maturity.

The role of lean body mass and physical activity in bone health in children.

In the context of physical education curricula, markers of physical fitness (e.g., aerobic capacity, muscular strength, flexibility, and body mass index or body fat) are usually evaluated in reference to health standards. Despite their possible mediating role in the relationship between weight-bearing or muscle forces and features of bone tissue, these attributes of fitness may not be the most relevant to predict skeletal health. It is therefore important to analyze the relative contribution of these factors to the variability in bone tissue of different parts of the skeleton, and to analyze it by gender, as sensitivity to mechanical loading can diverge for boys and girls. We compared the effects of habitual physical activity (PA) and lean mass, as surrogates of weight-bearing and muscle forces, and of physical fitness (aerobic and muscle capacity of lower and upper limbs) on bone mineral content (BMC) and size of total body, lumbar spine, femoral neck, and 1/3 radius in 53 girls and 64 boys from 7.9 to 9.7 years of age. After controlling for bone age, body mass, body height, and calcium intake, lean mass was the most important predictor of bone size and/or mineral in both genders (p < 0.05), while habitual weight-bearing PA positively influenced BMC in boys (p < 0.05). The effect of muscle in bone was not determined by PA and fitness score did not explain bone variability. Femoral neck was the bone site more closely associated with mechanical loading factors; boys with a PA > 608 counts/min/day (~105 min/day of moderate and vigorous intensity) showed 13-20% more BMC than those with less physical activity, and girls with a lean mass >19 kg showed 12-19% more BMC than those with less lean mass. These findings suggest that lean mass was the most important predictor of bone size and/or mineralization in both genders, while habitual weight-bearing PA appears to positively impact on bone mineral in prepubertal boys and that both lean mass and PA need to be considered in physical education curricula and other health-enhancing programs.