Determinant Factors of the Squat Jump in Sprinting and Jumping Athletes.

The aim of this study was to assess the relationship between strength variables and maximum velocity (Vmax) in the squat jump (SJ) in sprinting and jumping athletes. Thirty-two sprinting and jumping athletes of national level (25.4 ± 4.5 years; 79.4 ± 6.9 kg and 180.4 ± 6.0 cm) participated in the study. Vmax in the SJ showed significant relationships with peak force 1 (PF1) (r = 0.82, p ≤ 0.001), peak force 2 (PF2) (r = 0.68, p ≤ 0.001), PF2 by controlling for PF1 (r = 0.30, non-significant), the maximum rate of force development at peak force 1 (RFDmax1) (r = 0.62, p ≤ 0.001), mean RFD 1 (RFDmean1) (r = 0.48, p ≤ 0.01), mean RFD 2 (RFDmean2) (r = 0.70, p ≤ 0.001), force at RFDmax1 (r = 0.36, p ≤ 0.05), force at RFDmax2 (r = 0.83, p ≤ 0.001) and force at RFDmax2 by controlling for PF1 (r = 0.40, p ≤ 0.05). However, Vmax in the SJ was associated negatively with the ratio PF2/PF1 (r = -0.54, p ≤ 0.01), time at peak force 2 (Tp2) (r = -0.64, p ≤ 0.001) and maximum rate of force development at peak force 2 (RFDmax2) (r = -0.71, p ≤ 0.001). These findings indicate that the peak force achieved at the beginning of the movement (PF1) is the main predictor of performance in jumping, although the RFDmax values and the ratio PF2/PF1 are also variables to be taken into account when analyzing the determinant factors of vertical jumping.

La actividad física en adolescentes no muestra relación con el consumo máximo de oxígeno / Physical activity is not associated with maximum consumption of oxygen in adolescents

Introducción y objetivos: La capacidad aeróbica es un potente factor de riesgo cardiovascular e indicador de salud. La actividad física es también reconocida como un importante componente del estilo de vida saludable. Sin embargo, la relación entre capacidad aeróbica y actividad física no está muy clara en adolescentes. Por ello, el objetivo del presente estudio fue examinar la asociación entre el VO2max como medida objetiva de la capacidad aeróbica y la actividad física, medida con el International Physical Activity Questionnaire (IPAQ), en adolescentes. Método: En el estudio participaron un total de 155 adolescentes (79 chicos y 76 chicas) de 15-18 años de edad. El VO2max fue medido de manera directa a través de un analizador de gases portátil (K4b2, Cosmed) durante la realización del 20 Meter Shuttle Run test. El grado de actividad física y el gasto energético se estimaron mediante el IPAQ en su versión corta autoadministrada. Resultados: Los chicos mostraron una mayor capacidad aeróbica y nivel de actividad física con respecto a las chicas (p≤0.001). No se encontraron relaciones significativas entre el gasto energético estimado (MET) y las variables de capacidad aeróbica, tanto en chicos como en chicas. Conclusiones: El nivel de actividad física medido a través del IPAQ no se relaciona consistentemente con la capacidad aeróbica (VO2max), por lo que recomendamos la utilización de otros métodos de medida más objetivos, fiables y factibles de ser utilizados en el ámbito educativo y sanitario. En base a los resultados que muestran una baja capacidad aeróbica de los adolescentes estudiados, coincidimos con la tendencia actual de demandar el desarrollo de programas específicos para mejorar la capacidad aeróbica de la población, con objeto de prevenir enfermedades cardiovasculares en la edad adulta (AU)

Introduction and objectives: Aerobic capacity is a potent factor of cardiovascular risk and health index. Physical activity is recognized also as an important component of healthy wayof life. Nevertheless, the relation between aerobic capacity and physical activity is not very clear in adolescents. The main purpose of this study was to examine the relationship between VO2max, as objective measure of the aerobic capacity, and the physical activity measured by means of the International Physical Activity Questionnaire (IPAQ), in adolescents. Method: A total of 155 adolescents of 15-18 years-old (79 boys and 76 girls) participated in the study. VO2max was objectively assessed using a portable gas analyzer (K4b2, Cosmed) during the 20 m Shuttle Run Test. Physical activity level and energy expenditure were estimated using the short IPAQ form. Results: Boys showed significantly bigger aerobic capacity and physical activity level than girls (p≤0.001). No relationships were found between energy expenditure measured by the IPAQ and variables of aerobic capacity in any gender. Conclusions: Physical activity level assessment by means of IPAQ (short auto-administered version) is not very reliable as predictive factor of aerobic capacity (VO2max) in adolescents. Therefore it is recommended to use other more objective measure methods, reliable and feasible that can be used in the educational and sanitary area. Finally, on the basis of the results that show a low aerobic capacity of the studied adolescents, we coincide with the current trend of demanding the development of specific programs to improve the aerobic capacity of the population, in order to prevent cardiovascular diseases in adult age (AU)

Artificial neural network-based equation for estimating VO2max from the 20 m shuttle run test in adolescents.

OBJECTIVE: To develop an artificial neural network (ANN)-equation to estimate maximal oxygen uptake (VO(2max)) from 20m shuttle run test (20 mSRT) performance (stage), sex, age, weight, and height in young persons. METHODS: The 20 mSRT was performed by 193 (122 boys and 71 girls) adolescents aged 13-19 years. All the adolescents wore a portable gas analyzer to measure VO(2) and heart rate during the test. The equation was developed and cross-validated following the ANN mathematical model. The neural net performance was assessed through several error measures. Agreement between the measured VO(2max) and estimated VO(2max) from Léger's and ANN equations were analysed following the Bland and Altman method. RESULTS: The percentage error was 17.13 and 7.38 for Léger and ANN-equation (P<0.001), respectively, and the standard error of the estimate obtained with Léger's equation was 4.27 ml/(kg min), while for the ANN-equation was 2.84 ml/(kg min). A Bland-Altman plot for the measured VO(2max) and Léger-VO(2max) showed a mean difference of 4.9 ml/(kg min) (P<0.001), while the Bland-Altman plot for the measured VO(2max) and ANN-VO(2max) showed a mean difference of 0.5 ml/(kg min) (P=0.654). In the validation sample, the percentage error was 21.08 and 8.68 for Léger and ANN-equation (P<0.001), respectively. CONCLUSIONS: In this study, an ANN-based equation to estimate VO(2max) from 20 mSRT performance (stage), sex, age, weight, and height in adolescents was developed and cross-validated. The newly developed equation was shown to be more accurate than Léger's. The proposed model has been coded in a user-friendly spreadsheet.