Indicadores de masa muscular esquelética y rendimiento araeróbico en niños y adolescentes

Study 1. Objective. To provide reference data of regional and total SMM and FFM derived from anthropometry among age, sex and sport participation groups for healthy Caucasian children and adolescents, accounting for body size and maturation. Study design. Cross-sectional data of 1438 participants aged 8-18y. FFM and SMM were estimated from anthropometric variables. General linear model of mixed factors was used to analyze variance of FFM or SMM across groups and confounders. Ln-ln regression analysis was applied to describe SMM scaling associations with height. Results. Only active boys increased significantly their regional muscularity from primary to secondary school (arm, ∆0.78cm; thigh, ∆1.44cm; calf, ∆1.16cm) and from secondary to high school (arm, ∆2.81cm; thigh, ∆2.51cm; calf, ∆1.88cm; all P<0.0001). Conclusions. Our findings showed sex differences in the relationship between total and regional SMM and age. A novel contribution was that sport practice may affect SMM accrual after puberty, and growth of regional muscle-to-height ratio before PHV. Study 2. Objectives. To analyze the validity and agreement between laboratory and field methods to estimate FFM and SMM in children, adolescents, and young adults. And, to explore construct validity. Study design. Validation studies were designed using a large dataset of children and adolescents aged 6-21y. Body composition was assessed by isotope dilution method, dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and anthropometry (ANT). Static and dynamic strength were tested. Concurrent validity was analyzed by differences between methods and concordance coefficient correlation; agreement by Bland-Altman, and construct validity by correlations between muscle and strength. Results. A total of 531 measures were analyzed (287 boys). FFM measures from alternative techniques underestimated FFM measures from deuterium dilution. Isometric strength correlated better with lean and muscle mass variables than explosive dynamic tests. Conclusions. The results did not confirm agreement between methods. There was not a perfect method for all situations. The results evidence the need for developing specific models to estimate FFM and SMM in physically active prepubertal and pubertal youth. Study 3. Objective. To explore the associations and predictive capacity of regional SMM in isometric strength, and water distribution in dynamic strength. Study design. 1) Intracellular water (ICW) and Sprint Performance in 158 adolescents aged 12-18y (15.0 ± 1.5y). 2) Regional SMM and Lower Limb Strength (LLS) in 166 healthy adolescents aged 12-18y. Best performance out of two measures of 30m-sprint and LLS was selected. Athletes were identified with ad hoc questionnaires. The best-correlated variables were included in a stepwise regression analysis. Results. 1) SMM (kg), the athlete condition and %ICW were identified as predictors of speed in 30m (P<0.001, R2 = 0.620). 2) Similar results were found for a model including SMM (kg), athlete condition, and height (R2 = 0.488, P<0.001) and for an alternative model including CCG, athlete condition, sex and height (R2 = 0.484, P<0.001). Conclusions. One of the main findings was that ICW assessed by bioimpedance analysis was a significant predictor of sprint performance in adolescents. And, that, a simple measure like corrected calf girth was found to contribute significantly for estimating lower limb strength almost as much as whole lean body mass.The acquisition of lean body mass (LBM) during childhood and adolescence must be a main concern to ensure motor development and healthy growth. Participation in regular physical activity programs during the growth period plays a positive role in bone and lean mass accrual in addition to diverse health-derived benefits but there is need to consider account for biological maturity and body size. Methodologies to predict skeletal muscle mass (SMM) or fat-free mass (FFM) are not error-free. Thus, the relationship between performance and muscularity may be affected. The analysis of the associations between known models to estimate LBM with anaerobic performance (strength) should be pertinent to evaluate construct validity. The relationship between strength and muscle size has been extensively explored in adults but less is known in adolescents. Furthermore, hydration has been barely associated with anaerobic performance. This is a paradoxical situation because the child is mainly involved in high intensity and short duration exercises in most daily tasks, spontaneous physical activity or sports. Three different studies were carried out in a sample of children, adolescents, and young adults

Reference values of total and regional skeletal muscle mass in children and adolescents

Introduction: The acquisition of skeletal muscle mass (SMM) during childhood and adolescence must be a main concern to ensure healthy growth and improved motor development. Moreover, peak SMM increment must happen during youth, which would determine adulthood health and performance. Although some indicators of SMM have been using for assessment of nutrition status since the seventies like upper arm circumference or arm areas there is insuffi cient SMM data throughout childhood and adolescence to establish references norms. The first aim of this study, therefore, was to analyze trends of fat free mass (FFM) and regional and total SMM. The second objective was to compare trends between SMM and FFM by age and gender. Method: Cross-sectional data of 1103 healthy volunteers were analyzed (13.3 ± 2.5 yrs, BMI=20.1 ± 3.4 kg/m2; 323 girls and 780 boys). They were recruited from local primary schools, high-schools and local sport clubs. Anthropometry in accordance with ISAK guidelines was used to measure: triceps, thigh and calf skinfolds, and arm, thigh and calf circumferences were assessed by a caliper and tape respectively. Regional muscle areas were calculated from the corrected limb circumferences. FFM was estimated by anthropometric-derived equation. Validated age-specifi c models were applied to obtain SMM based on anthropometric variables (Poortmans’ (0.000) while FFM showed 688.7 (P>0.000). Sex interaction was found. Conclusions: Our fi ndings show that there is a diff erence between boys and girls in the relationship between total SMM and age. Regional muscle areas from the upper limbs don’t develop in linear fashion with age in contrast to development in the lower extremity areas. These results suggest that upper and lower muscle areas growth is diff erent in terms of timing. Longitudinal studies are required to confirm these results.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Construct validity of the physical activity questionnaire for adolescents (paq-a): maximal oxygen uptake

Introduction: The Physical Activity Questionnaire for adolescents (PAQ-A) is a cost-effective tool to assess physical activity (PA) patterns during adolescence and it has been widely used in research and field settings. Convergent validity of PAQ-A has been confirmed in several countries (Bervoets et al., 2014; Janz, Lutuchy, Wenthe, & Levy, 2008; Martinez-Gomez et al., 2009). However, the construct validity has often been overlooked. Therefore, the aim of this study was to analyze the construct validity of PAQ-A, using maximal oxygen uptake as criterion. Methods: One hundred and seventy-eight (n=99 boys, n=79 girls) adolescents (14.2±1.9 years, 21.1±4.1 BMI) participated in this study. A PA score was estimated by PAQ-A and additionally a sport history was recorded. BMI, waist circumference (WC) and fat mass percent (FMP) were assessed by anthropometric measurements as adiposity markers. Aerobic fitness (VO2Max) was assessed by a progressive continuous test (Chester Step Test). Associations between PA-score and criterions were analyzed by Spearman correlations; a one-way ANOVA was conducted to detect differences between each item level from the PAQ-A; independent sample t tests were used to compare values between boys and girls, and athletes and non-athletes. Results: The results showed moderate significant positive correlations between VO2Max and the PAQ-C for total score (rho = 0.28, P<0.01) and items 5, 6, 7 and 8 (rho = 0.24; rho = 0.25; rho = 0.22; rho = 0.25, all P<0.05; respectively). Adolescents who were enrolled in competitive and organized sport practice had higher scores on the questionnaire (2.8 vs 2.5 average score) as well as higher VO2Max values (37.4 vs 34.2 ml/kg/min). Discussion: Our data confirm the PAQ-A had acceptable construct validity when using VO2Max as criterion. Moreover, our results suggest that information from some items could be more related with some health markers than others. References: Bervoets, L., Van Noten, C., Van Roosbroeck, S., Hansen, D., Van Hoorenbeeck, K., Verheyen, E., . . . Vankerckhoven, V. (2014). Reliability and Validity of the Dutch Physical Activity Questionnaires for Children (PAQ-C) and Adolescents (PAQ-A). Arch Public Health, 72(1), 47. doi: 10.1186/2049-3258-72-47 Janz, K. F., Lutuchy, E. M., Wenthe, P., & Levy, S. M. (2008). Measuring activity in children and adolescents using self-report: PAQ-C and PAQ-A. Medicine and Science in Sports and Exercise, 40(4), 767-772. doi: 10.1249/MSS.0b013e3181620ed1 Martinez-Gomez, D., Martinez-de-Haro, V., Pozo, T., Welk, G. J., Villagra, A., Calle, M. E., . . . Veiga, O. L. (2009). [Reliability and validity of the PAQ-A questionnaire to assess physical activity in Spanish adolescents]. Rev Esp Salud Publica, 83(3), 427-439. Contact: [email protected] This work was supported by the Spanish Ministry of Education, Culture and Sport (AP2010-0583), Spanish Ministry of Economy and Competitiveness (DEP2011-30565) and the University of Málaga (Campus of International Excellence Andalucía Tech).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Associations of physical activity with blood pressure, body composition and maturation level in adolescents: the GEOS Study

Introduction The association between physical activity (PA) and resting blood pressure (BP) is poorly understood in adolescents (Kelley, Kelley, & Tran, 2003), since several variables such as body composition, maturation level or sex, which interfere with, must be analyzed (Muntner, He, Cutler, Wildman, & Whelton, 2004). Therefore, the aim of this study was to explore the association of PA, body composition, blood pressure, and maturation in adolescent boys and girls. Methods: Two hundred and nine (n=114 boys, n=95 girls) healthy adolescents (15.6±1.6 years, 21.9±4.3 BMI) were volunteers. A PA score was estimated by Physical Activity Questionnaire (PAQ-A). BMI, waist circumference (WC) and fat mass percent (%FM) were assessed by anthropometric measurements as adiposity markers. Tanner’s maturation stages were evaluated and systolic and diastolic blood pressure (SBP and DBP) were measured by OMRON sphygmomanometer. SBP and DBP indexes (SBPI and DBPI) were calculated as mmHg/height (cm). Spearman rank order correlations were used to explore associations between variables after control to maturation. Results: All the relationships between parameters showed a positive correlation. There were significant associations between BP variables and BMI (SBP r=0.202, P<0.01; DBP r=0.305, P<0.001), and WC (SBP r=0.197, P<0.01; DBP r=0.295, P<0.001). PA score was only related with body composition variables either girls or boys. Also, there were significant correlations between %FM and BP variables (SBP r=0.332, P <0.01; DBP r=0.330, P<0.01; DBPI r=0.308, P <0.01) in girls but not in boys. Discussion: Our data confirm the relationship between BP and body composition variables as WC and BMI (Rosa, Fonseca, Oigman, & Mesquita, 2006). Nevertheless, we could not find any association between PA and BP. The recently developed SBPI and DBPI were not better associated with any variable than simple BP. These results should be considered carefully since measuring physical activity by objective methods could have changed the conclusions. So, other studies have reported a negative association between PA measured by accelerometry and BP (Hearst, Sirard, Lytle, Dengel, & Berrigan, 2012; Kelley, Kelley, & Tran, 2003). Further prospective studies using accelerometry or larger samples must be need in order to explore deeply the impact of PA on BP in adolescents. References Hearst, M. O., Sirard, J. R., Lytle, L., Dengel, D. R., & Berrigan, D. (2012). J Phys Act Health, 9(1), 78-85. Kelley, G. A., Kelley, K. S., & Tran, Z. V. (2003). Prev Cardiol, 6(1), 8-16. Muntner, P., He, J., Cutler, J. A., Wildman, R. P., & Whelton, P. K. (2004). JAMA, 291(17), 2107-2113. Rosa, M. L., Fonseca, V. M., Oigman, G., & Mesquita, E. T. (2006). Arq Bras Cardiol, 87(1), 46-53.This work was supported by the Spanish Ministry of Education, Culture and Sport (AP2010-0583), Spanish Ministry of Economy and Competitiveness (DEP2011-30565) and Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

The Importance of Biological Maturation and Years of Practice in Kayaking Performance

Previous canoe sprint studies evaluated the best paddlers of their categories. This investigation aimed to identify the importance of biological maturation and athletes’ experience in kayaking performance and observe possible differences regarding anthropometry, years of practice, and performance. Eighty under 14 years of age (U14) and fifty under 16 years of age (U16) kayakers aged 13.40 ± 0.54 and 15.25 ± 0.61 years were evaluated. Kayakers were assessed for anthropometry (body mass (kg); stretch stature (cm); and sitting height (cm)), performance (time at 3000 m for U14 and 5000 m for U16 kayakers), and somatic maturation (predicted adult height (PAH) and maturity offset). In the U14 kayakers, years of practice, sitting height, and maturity offset showed significant differences (p < 0.05) between the Top10 and Middle, and Middle and Bottom10 performance times. Significantly higher (p < 0.05) sitting heights were identified between the Top10 and Middle U16 kayakers. Significant differences (p < 0.05) were observed for maturity offset and PAH% between the Top10 and Middle groups compared to the Bottom10 group. In conclusion, this research shows differences in the maturity status of young U14 and U16 kayakers, identifying that the more biologically mature individuals, with more years of specific practice, achieved better performances

Estimation of internal abdominal fat from anthropometry measurements in children

Introduction: Internal abdominal fat (IAF) measured by dual energy X-ray absorptiometry (DXA) has been proposed as subrogate of visceral adipose tissue, which is a cornerstone measurement for screening of metabolic syndrome1,2. However, measuring IAF is time-consuming, expensive and impractical for field studies with children. Since 1990, anthropometric models have been developed to estimate IAF in adults, but no models exist for children. Because of the high prevalence of childhood obesity, the assessment of IAF is a major factor in the evaluation metabolic risk. Therefore, the aim of this study was to develop an anthropometry-based model to estimate IAF in children. Methods: Forty-one (n=24 boys, n=17 girls) healthy Caucasian children (age 11.4±0.6 years, BMI 20.1±3.9 Kg/m2) were volunteers. Anthropometric measurements (waist and hip circumferences, abdominal sagittal diameter and skinfolds) were taken in accordance with ISAK guidelines. Total body and IAF (dependent variable) body composition were measured by DXA. Stepwise regression analysis was carried out to obtain the fittest variables and beta coefficients in order to develop the equation that predicts IAF with a high squared R and a low standard error of estimation. Results: The best-correlated variables with IAF were BMI, waist circumference, calf and subscapular skinfolds (r=0.900; r=0.946; r=0.901; r=0.900; respectively, all P<0.001). The best model for estimating the IAF included waist circumference and subscapular skinfold (R2=0.93 SEE=115.43; P<0.001). The estimated model was IAF (g) = -1332.89 + (18.515*WC) + (773.39*SubSKF). Conclusion: We developed a model, which accurately predict IAF in children, affording a practical tool to quantify this variable without expensive techniques such as DXA. However, external cross-validation must be performed in order to confirm the model validity. Additionally, construct validity should be carried out to determine the applicability of this measurement in children. References: 1. Hill AM, La_Forgia J, Coates AM, Buckley JD, Howe PR. Estimating abdominal adipose tissue with DXA and anthropometry. Obesity. 2007 Feb;15(2):504-10. 2. Kaul S, Rothney MP, Peters DM, Wacker WK, Davis CE, Shapiro MD, et al. Dual-energy X-ray absorptiometry for quantification of visceral fat. Obesity. 2012 Jun; 20(6):1313-8.This work was supported by the Spanish Ministry of Education, Culture and Sport (AP2010-0583), Spanish Ministry of Economy and Competitiveness (DEP2011-30565) and University of Málaga. Campus of International Excellence Andalucía Tec

Age and Training-Related Changes on Body Composition and Fitness in Male Amateur Cyclists

Master athletes are considered as a model of healthy aging because they can limit the age-related decline of physiological abilities compared to sedentary individuals. The main objective of this study is to analyze age-related changes and annual training on body composition (BC) and cardiorespiratory fitness (CRF) parameters. The participants in this retrospective cross-sectional study were 176 male cyclists, aged 40–60 years. BC was evaluated through anthropometric measurements and CRF was determined by an incremental cycle ergometer test to exhaustion. A comparative study between age groups was carried out through a one-way ANOVA test and the associations between the variables were assessed by Spearman’s correlation coefficients and multiple regression analysis to estimate the performance. Training was generally associated with a decrease in both body weight and body fat (p 0.05). In the performance prediction model, the included variables explained 52% of the variance. In summary, the changes induced by age were minimal in BC and negligible in CRF, whereas HR decreased with age. Training load was generally associated with a decrease in body weight, BMI and body fat percentage that was particularly notable in the abdominal skin folds. A decrease in HRrest was observed as a vagal effect due to kilometers cycled per year, and age did not seem to have a significant effect. The annual cycling kilometers were associated with to high PPO that is greater in the M40 group and a non-significant upward trend in VO2max

Lignocellulosic Biomass as a Source of Raw Materials for the Synthesis of Polyurethanes

Precursors have been satisfactorily synthesized from lignocellulosic biomass for later use in the synthesis of polyurethanes resulting in competitive final properties with those of petroleum derived polyurethanesWe thank the Basque Government (IT-776-13, ELKARTEK-KK2017/00003) for the financial support. We also wish to acknowledge the “Macrobehavior-Mesostructure-Nanotechnology” SGIker unit from the University of the Basque Country, for their technical support

El coste de la construcción medieval: materiales, recursos y sistemas constructivos para la petrificación del paisaje entre los siglos XI y XIII

Edición a cargo de Rocío Maira Vidal y Ana RodríguezLa dificultad de estudiar los costes de la construcción entre los siglos XI y XIII por la ausencia de documentos originales que hagan mención a las cuentas y gastos revela la necesidad de abordar su estudio a partir de nuevos caminos. En este libro se propone una nueva metodología para acometer el estudio de los costes a partir del análisis comparativo de los sistemas constructivos y de los recursos empleados. La nueva metodología propuesta permite conocer aquellas actividades que supusieron un mayor gasto para los promotores de las obras por requerir abundante mano de obra, una alta especialización de sus trabajadores o cuantiosos recursos naturales, a veces distantes de la obra. Confiamos que este libro responderá interesantes cuestiones sobre el desarrollo de la economía y la sociedad plenomedievales.Peer reviewe