Prediction of Performance in a Short Trail Running Race: The Role of Body Composition.

The aim of the present study was to examine the role of the classical physiological model of endurance running performance - maximal oxygen uptake (VO2max), %VO2max at ventilatory thresholds (VT), work economy, lactate levels, and body composition on the prediction of short trail running performance. Eleven male trail runners (age 36.1 ± 6.5 years, sport experience 6.6 ± 3.8 years, and mean ± standard deviation) were examined for fat mass and skeletal muscle mass, and performed a graded exercise test to measure VO2max, vVO2max, and VT. Also, they participated in a short 27 km trail run with a positive elevation of +1750 m. Age, years of training and skeletal muscle mass did not correlate with race time (P > 0.05), and fat mass and body mass index (BMI) showed significant correlations with race time (P < 0.05). Heart rate, velocity and VT1 and VT2 were not associated with race time (P > 0.05). Only vVO2max (P = 0.005) and VO2max (P = 0.007) is correlated to race time. Multiple regression models for VO2max accounted for 57% of the total variance. The vVO2max model variable accounted for 60% and the fat mass model for 59.5%. Finally, the combined VO2max and fat mass model explained 83.9% of the total variance (P < 0.05 in all models). The equation for this model is "race time (min) = 203.9956-1.9001 × VO2max + 10.2816 × Fat mass%" (R 2 = 0.839, SEE = 11.1 min, and P = 0.0007). The classical variable VO2max together with fat mass percent are two strong predictors for short trail running performance.

VO2máx de laboratorio versus Course Navette. Un estudio de concordancia en sujetos físicamente activos / Laboratory VO2max versus Course Navette. An agreement study on physically active subjects / Laboratório VO2máx versus Course Navette. Estudo de concordância em indivíduos fisicamente ativos

OBJETIVO: El objetivo del presente trabajo ha sido comprobar la concordancia entre el valor estimado de VO2máx, a partir del test de Course Navette, (VO2CN), comparado con la medición directa del consumo de oxígeno en laboratorio (VO2LAB) en un grupo jóvenes de ambos sexos. MÉTODOS: Participaron en el estudio 28 sujetos, físicamente activos (19 varones y 9 mujeres) de 20.5 +/- 2.1 años, peso: 67.1 +/- 11.9 kg, talla: 171.0 +/- 8.5 cm, IMC: 22.8 +/- 2.5 kg/m2. El VO2máx para todos los participantes fue determinado por el método directo en el laboratorio con un test incremental máximo (VO2LAB) y por medio de la estimación del test de Course Navette, (VO2CN) con un intervalo máximo de una semana entre pruebas. Se realizaron estudios de correlación de Pearson y un estudio de concordancia de Bland-Altman entre los valores de VO2LAB y VO2CN. RESULTADOS: Se comprueba una correlación moderada significativa entre VO2LAB y VO2CN (r=0.53; IC95% (0.19 a 0.75), p = 0.003). Se obtienen unos valores medios de VO2LAB de 46.1 +/- 6.7 mL/kg/min y de 47.23 +/- 6.1 para VO2CN, no presentando diferencias significativas (p = 0.21). Se comprueba con el análisis de concordancia de Bland-Altman, que no existe error sistemático (diferencia: 1.4889 ml/kg/min (-0.895 a 3.8727), p = 0.21) ni error proporcional entre los valores de VO2LAB y VO2CN (Ƭ= -0.089 (-0.33 a 1.89), p = 0.481). Existen diferencias en el VO2LAB entre hombres y mujeres (p = 0.01). CONCLUSIÓN: Los valores VO2LAB y VO2CN presentan valores bajo-moderados de correlación entre métodos, sin embargo la estimación del consumo máximo de oxígeno mediante el test de Course Navette es un método adecuado en sujetos jóvenes físicamente activos, sin presentar diferencias en los valores medios, ni error proporcional, aunque se observan amplios límites de concordancia

OBJECTIVE: The objective of this study was to verify the agreement between the estimated value of VO2max, from the Course Navette, (VO2CN), compared with the direct measurement of oxygen consumption in laboratory (VO2LAB) in a group of young people of both sexes. METHODS: The study involved 28 physically active subjects (19 males and 9 women) of 20.5 +/- 2.1 years old, eight: 67.1 +/- 11.9 kg, height: 171.0 +/- 8.5 cm, BMI: 22.8 +/- 2.5 kg/m2. The VO2max for all participants was determined by the direct method in the laboratory with a graded test (VO2LAB) and by means of the estimation of the course Navette Test (VO2CN) with a maximum interval of one week between tests. Pearson correlation coefficients were performed to assess associations between variables and a Bland-Altman test to asses agreement between the values of VO2LAB and VO2CN. RESULTS: A significant correlation between VO2LAB and VO2CN was found (r = 0.53; IC95% (0.19 to 0.75), p = 0.003). Average values of VO2LAB of 46.1 +/- 6.7 mL/kg/min and 47.23 +/- 6.1 mL/kg/min for VO2CN are obtained, not presenting statistical differences (p = 0.21). The concordance analysis of Bland-Altman found no bias (difference: 1.4889 ml/kg/min (-0.895 to 3.8727), p = 0.21) and proportional error VO2LAB and VO2CN (Ƭ=-0089 (-0.33 to 1.89), p = 0.481). There are differences in the VO2LAB between men and women (p = 0.01). CONCLUSION: The values of VO2LAB and VO2CN present low-moderate correlation coefficients between methods, however the estimation of maximum oxygen consumption by the Course Navette test is an appropriate method in young subjects physically active, without differences in the average values, nor proportional error, although it is observed broad limits of concordance

OBJETIVO: o objetivo deste estudo foi verificar a concordância entre o valor estimado do VO2máx, a partir do teste do Curso Navette, (VO2CN), em comparação com a mensuração direta do consumo de oxigênio em laboratório (VO2LAB) em um grupo de ambos os sexos. MÉTODOS: participaram 28 indivíduos fisicamente ativos (19 homens e 9 mulheres) de 20.5 +/- 2.1 anos, peso: 67 +/- 11.12 kg, tamanho: 171 +/- 8.5 cm, IMC: 22.5 +/- 2.5 kg/m2. O VO2máx para todos os participantes foi determinado pelo método direto no laboratório com um teste incremental máximo (VO2LAB) e por meio da estimativa do curso de Teste de Navette (VO2CN) com um intervalo máximo de uma semana entre os testes. Foram realizados estudos de correlação de Pearson e um estudo de concordância de Bland-Altman entre os valores de VO2LAB e VO2CN. RESULTADOS: uma correlação significante entre VO2LAB e VO2CN foi décima (r = 53; IC95% (0.19 a 0.75), p = 0.003). Os valores médios de VO2LAB de 46.1 +/- 6.7 mL/kg/min e 47.23 +/- 6.1 para VO2CN são obtidos, não apresentando diferenças significativas (p = 0.25). É décimo com a análise da concordância de Bland-Altman, que não há nenhum erro sistemático (diferença: 1.4889 mL/kg/min (-0.895 a 3.87), p = 0.21) nem o erro proporcionais entre os valores de VO2LAB e VO2CN (T =-0.089 (-0.33 a 1.89), p = 0.481). Existem diferenças no VO2LAB entre homens e mulheres (p= 0.01). CONCLUSÃO: os valores de VO2LAB e VO2CN apresentam valores baixos de correlação entre os métodos, porém a estimativa do consumo máximo de oxigênio pelo teste de course navette é um método adequado em indivíduos jovens fisicamente ativos, sem para apresentar diferenças nos valores médios, nem o erro contado, embora seja oca amplos límites de concordância

Longitudinal validity of abdominal adiposity assessment by regional bioelectrical impedance.

The main goal of this study was to analyze the longitudinal agreement between changes in trunk and abdominal adiposity variables assessed by DXA and portable bioimpedance device (ViScan). A total of 44 women, enrolled in a 4-month exercise intervention, were included in this analysis. Trunk/abdominal compartments were assessed by ViScan and DXA. Adjusted correlations for age and FM at first assessment (pre) were utilized to perform concurrent validation among methods and completed with an agreement analysis. We observed significant differences between the changes detected by DXA and ViScan for %TFM (difference = -1.41%; p < 0.05), and proportional bias (Kendall's Tau = 0.53; p < 0.0001). Changes in abdominal adiposity were similar (difference = -0.1037 z-score units, p = 0.53), although there was proportional bias (Kendall's Tau = -0.24, p < 0.022). ViScan has a limited capability to evaluated changes in trunk and abdominal adiposity, at least for clinical purposes in adult women.

Body composition changes after sport detraining period / Cambios de la composición corporal tras un periodo de desentrenamiento deportivo

Introduction: The infl uence of exercise in trained subjects has beneficial effects in the physical fi tness and body composition; however, detraining has an unfavorable effect in all of them. Objective: The current study was designed to ascertain the infl uence of a six week-detraining period on body composition in both well-trained young soccer players (GE, n = 43) and sedentary male adolescents (GC, n = 10). Methods: Forty-three well-trained soccer players and ten sedentary adolescents accepted to participate in the study. Body composition measurements included fat mass and skeletal muscle mass (SMM), which were estimated by anthropometry. In addition, total body water (TBW), intracellular water (ICW) and extracellular water (ECW) were assessed by bioelectrical impedance analysis (BIA) at the end of training and after detraining periods. Results: After the six-week-detraining period, signifi cant increments were found in TBW (35.5 ± 5.2 vs.36.7 ± 4.9 kg; p < 0.001), ICW (14.2 ± 1.8 vs. 14.8 ± 1.6 kg; p < 0.001) and ECW (21.5 ± 3.6 vs. 22.0 ± 3.4 kg; p < 0.001) in soccer players. Conversely, no changes were observed in ECW/TBW (0.4 ± 0.02 vs. 0.4 ± 0.02; p > 0.05) and ICW/TBW (0.6 ± 0.02 vs. 0.597 ± 0.02; p > 0.05) ratios. Finally, fat mass was significantly increased (8.6 ± 3.2 vs. 8.95 ± 3.1 kg; p < 0.01) in the detrained group. No signifi cant changes were found in SMM (21.2 ± 2.5 vs. 22.22 ± 2.8 kg, p > 0.05). Conclusions: After a six-week detraining period, body composition changed signifi cantly in well-trained adolescents. The main fi nding of this study was that increments of TBW and water distribution were observed in the soccer group, which refl ects an increase of fat free mass compartment. The physiological importance of this miss-adaptation needs to be elucidated in future research. Further studies on this topic are still required to assess its impact on physical performance.

Cambios de la composición corporal tras un periodo de desentrenamiento deportivo / Body composition changes after sport detraining period

Introducción: la influencia del ejercicio físico en sujetos entrenados tiene efectos beneficiosos en la condición física y la composición corporal. Sin embargo, el desentrenamiento tiene un efecto desfavorable en todas ellas. Objetivo: el propósito del estudio fue analizar los cambios de la composición corporal después de un periodo de desentrenamiento de seis semanas de duración en dos grupos: uno de 43 jóvenes varones jugadores de fútbol (grupo experimental [GE], n = 43), y un grupo control de escolares no activos de la misma edad (grupo control [GC], n = 10). Métodos: las variables de composición corporal fueron evaluadas mediante antropometría, para estimar la masa grasa (MG) y la masa muscular esquelética (MME), y mediciones de bioimpedancia eléctrica, para estimar agua corporal total (ACT), agua extra (AEC) e intracelular (AIC). Las mediciones se realizaron tanto en situación de entrenamiento como de desentrenamiento. Resultados: tras el desentrenamiento, se encontraron diferencias significativas en el ACT (35,5 ± 5,2 vs. 36,7 ± 4,9 kg), el AIC (14,2 ± 1,8 vs. 14,8 ± 1,6 kg) y el AEC (21,5 ± 3,6 vs. 22,0 ± 3,4 kg, p < 0,001 para todas las variables), sin existir diferencias en los ratios AEC/ACT (0,4 ± 0,02 vs. 0,4 ± 0,02) y AIC/ACT (0,6 ± 0,02 vs. 0,597 ± 0,02, ambos p > 0,05). La MG aumentó significativamente (8,6 ± 3,2 vs. 8.95 ± 3,1 kg, p < 0,01); sin embargo, la MME no sufrió modificaciones (21,2 ± 2,5 vs. 22,22 ± 2,8 kg, p > 0,05) Conclusiones: el principal resultado de este estudio fue que en un periodo de desentrenamiento de seis semanas se observaron aumentos del ACT y de su distribución en el grupo de jóvenes futbolistas. La importancia fisiológica de esta desadaptación en el rendimiento deportivo tiene que ser analizada en futuros estudios (AU)

Introduction: The influence of exercise in trained subjects has beneficial effects in the physical fitness and body composition; however, detraining has an unfavorable effect in all of them. Objective: The current study was designed to ascertain the influence of a six week-detraining period on body composition in both well-trained young soccer players (GE, n = 43) and sedentary male adolescents (GC, n = 10). Methods: Forty-three well-trained soccer players and ten sedentary adolescents accepted to participate in the study. Body composition measurements included fat mass and skeletal muscle mass (SMM), which were estimated by anthropometry. In addition, total body water (TBW), intracellular water (ICW) and extracellular water (ECW) were assessed by bioelectrical impedance analysis (BIA) at the end of training and after detraining periods. Results: After the six-week-detraining period, significant increments were found in TBW (35.5 ± 5.2 vs. 36.7 ± 4.9 kg; p < 0.001), ICW (14.2 ± 1.8 vs. 14.8 ± 1.6 kg; p < 0.001) and ECW (21.5 ± 3.6 vs. 22.0 ± 3.4 kg; p < 0.001) in soccer players. Conversely, no changes were observed in ECW/TBW (0.4 ± 0.02 vs. 0.4 ± 0.02; p > 0.05) and ICW/TBW (0.6 ± 0.02 vs. 0.597 ± 0.02; p > 0.05) ratios. Finally, fat mass was significantly increased (8.6 ± 3.2 vs. 8.95 ± 3.1 kg; p < 0.01) in the detrained group. No significant changes were found in SMM (21.2 ± 2.5 vs. 22.22 ± 2.8 kg, p > 0.05). Conclusions: After a six-week detraining period, body composition changed significantly in well-trained adolescents. The main finding of this study was that increments of TBW and water distribution were observed in the soccer group, which reflects an increase of fat free mass compartment. The physiological importance of this miss-adaptation needs to be elucidated in future research. Further studies on this topic are still required to assess its impact on physical performance (AU)

Validez de los índices de masa corporal y de masa grasa como indicadores de sobrepeso en adolescentes españoles: estudio Esccola / Validity of body mass index and fat mass index as indicators of overweight status in Spanish adolescents: Esccola Study

Objetivo y fundamento: Comprobar la exactitud del índice de masa corporal (IMC), del índice de masa grasa (IMG) y del índice de masa libre de grasa (MLG) para diagnosticar y determinar valores de corte para el sobrepeso en una población de jóvenes adolescentes entre 12 y 18 años de edad. Sujetos y método: Se estudió a 150 niños (75 varones: edad media de 14,81 años [desviación estándar {DE} de 1,86], talla media de 168,8 cm [DE de 8,8], peso medio de 65,84 kg [DE de 16] e IMC medio de 22,89 kg/m2 [DE de 4,4]; 75 niñas: edad media de 14,88 años [DE de 1,94], talla media de 159,4 cm [DE de 7,6], peso medio de 54,77 kg [DE de 9,54] e IMC medio de 21,48 kg/m2 [DE de 3,1]). El porcentaje de masa grasa se determinó mediante el cálculo del agua corporal total con un espectrómetro de masas para razones estables y aplicando las constantes de hidratación de la MLG para cada edad. La definición de sobrepeso se realizó aplicando los valores de porcentaje de grasa de Taylor relativos a cada edad y correspondientes al punto de corte internacional de 25 kg/m2, que clasifica el estado de sobrepeso. Se aplicó un análisis de curvas receiver operating characteristics y se calcularon las áreas bajo la curva de cada índice (IMC, IMG y MLG), así como los valores de sensibilidad y especificidad. Resultados: En los niños, los valores predictivos positivos fueron del 78,1% para el IMC y del 89,2% para el IMG, mientras que para las niñas estos valores fueron del 34,8 y del 81,4%, respectivamente. Los valores predictivos negativos fueron del 81,4 y del 100% en los niños y del 98,1 y del 100% en las niñas para el IMC y el IMG, respectivamente. Las áreas bajo la curva del IMG para los niños (0,988, intervalo de confianza del 95% de 0,930-0,998) y las niñas (0,996, intervalo de confianza del 95% de 0,943-1,000) mostraron una alta capacidad de predicción para el diagnóstico de sobrepeso (AU)

Background and objectives: to determine the accuracy of body mass index (BMI), fat mass index (FMI) and fat-free mass index (FFMI) to find cut-off points related to overweight in adolescents aged 12–18 years.Subjects and method: 150 adolescents were assessed (75 boys aged 14.81±1.86yr, height 168.8±8.8cm, weight 65.84±16kg and BMI 22.89±4.4kg.m2, and 75 girls aged 14.88±1.94yr, height 159.4±7.6cm, weight 54.77±9.54kg and BMI 21.48±3.1kg.m2). Body composition was measured by using the deuterium dilution technique with an isotope ratio mass spectrometer and fat free mass hydration constants were applied.Subjects and method: Taylor's age-related overweight classification was applied and receiver operating characteristic (ROC) curves analyses were performed. Areas under curve were calculated for every index (BMI, FMI and FFMI). Sensitivity and specificity values of BMI and FMI to diagnose overweight were evaluated.Results: Among boys, predictive positive values for BMI were 78.1% and 89.2% for FMI; predictive positive values in girls was 34.8% for BMI and 81.4% for FMI. Predictive negative values were 81.4% and 100% in boys and 98.1% and 100% in girls for BMI and FMI. Areas under curve of FMI for boys (0.988, 95%CI: 0.930-0.998) and girls (0.996, 95%CI: 0.943–1.000) showed high accuracy for overweight diagnose. Cutoff points of 4.58kg.m2 in boys and 7.76kg.m2 in girls for FMI and 23.07kg.m2 in boys and 23.18kg.m2 in girls for BMI had high sensitivity and specificity as indicators of overweight classification

[Validity of body mass index and fat mass index as indicators of overweight status in Spanish adolescents: Esccola Study]. / Validez de los índices de masa corporal y de masa grasa como indicadores de sobrepeso en adolescentes españoles: estudio Esccola.

BACKGROUND AND OBJECTIVES: To determine the accuracy of body mass index (BMI), fat mass index (FMI) and fat-free mass index (FFMI) to find cut-off points related to overweight in adolescents aged 12-18 years. SUBJECTS AND METHOD: 150 adolescents were assessed (75 boys aged 14.81+/-1.86yr, height 168.8+/-8.8cm, weight 65.84+/-16kg and BMI 22.89+/-4.4kg x m(2), and 75 girls aged 14.88+/-1.94yr, height 159.4+/-7.6cm, weight 54.77+/-9.54kg and BMI 21.48+/-3.1kg x m(2)). Body composition was measured by using the deuterium dilution technique with an isotope ratio mass spectrometer and fat free mass hydration constants were applied. Taylor's age-related overweight classification was applied and receiver operating characteristic (ROC) curves analyses were performed. Areas under curve were calculated for every index (BMI, FMI and FFMI). Sensitivity and specificity values of BMI and FMI to diagnose overweight were evaluated. RESULTS: Among boys, predictive positive values for BMI were 78.1% and 89.2% for FMI; predictive positive values in girls was 34.8% for BMI and 81.4% for FMI. Predictive negative values were 81.4% and 100% in boys and 98.1% and 100% in girls for BMI and FMI. Areas under curve of FMI for boys (0.988, 95%CI: 0.930-0.998) and girls (0.996, 95%CI: 0.943-1.000) showed high accuracy for overweight diagnose. Cutoff points of 4.58kg x m(2) in boys and 7.76kg x m(2) in girls for FMI and 23.07kg x m(2) in boys and 23.18kg x m(2) in girls for BMI had high sensitivity and specificity as indicators of overweight classification. CONCLUSIONS: FMI showed high accuracy for overweight screening. Thus, our cut-off points may be useful as a tool to surveillance children's overweight on clinical and epidemiologic settings.