Relación entre las características de la composición corporal y el rendimiento físico general y específico en competidores de taekwondo chilenos de nivel nacional de ambos sexos: un estudio observacional

Introduction: The purpose of this study was to examine the relationship between body composition characteristics and general and specific physical performance in Chilean national level TKD competitors of both sexes. Material and methods: Through an observational design 14 competitors of different categories of body weight and who usually compete in regional and national level tournaments age 19 (3) years; size 164 (10) cm; body weight 62 (10) kg; years of experience 7.2 (2.9) years. They participated in this study. Different characteristics of body composition that included body weight (kg) (PC), fat mass (kg), (MG), percentage of fat mass (% MG), muscle mass (kg) (MM) were evaluated and the body mass index (Kg/m2) (BMI). On the other hand variables of the general RF included squat jump (cm) (SJ), countermovement jump (cm) (CMJ), linear speed in 5-m (s) (5-M) and 20-m shuttle run test (min) (20MSR) and specifically the specific agility test in taekwondo (s) (TSAT) and the multiple frequency kick speed test (FSKTMULT) specifically the rate of decrease of kicks (FSKTMULT KDI%) and the maximum number of kicks executed (FSKTMULT MAX). Results: Among the main findings of the study, a significant large relationship (p <0.00) between% MG, MG and MM and most of the general physical performance variables analyzed was documented. Specifically, significant significant relationships (p<0.05) were observed between %MG, MG and MM and the TSAT test. While a significant large relationship was documented between MM and FSKTMULT MAX (p<0.03) and between MG and FSKTMULT KDI% (p<0.04). As moderate to low correlations were observed between the PC and the BMI in most of the physical performance variables analyzed. Conclusions: Our data suggest that a low% MG and MG followed by adequate MM are related to the specific general physical performance in Chilean national TKD competitors of both sexes.Introducción: El objetivo fue examinar la relación entre las características de la composición corporal y el rendimiento físico general y específico en competidores de TKD de nivel nacional de Chile de ambos sexos. Material y métodos: Diseño observacional con 14 competidores de diferentes categorías de peso corporal y que compiten habitualmente en torneos de nivel regional y nacional edad 19 (3) años; talla 164 (10) cm; peso corporal 62 (10) kg; años de experiencia 7,2 (2,9) años participaron en este estudio. Se evaluaron el peso corporal (kg) (PC), la masa grasa (kg), (MG), el porcentaje de masa grasa (%MG), la masa muscular (kg) (MM) y el índice de masa corporal (kg/m2) (IMC). Variables del RF general incluyeron squat jump (cm) (SJ), countermovement jump (cm) (CMJ), velocidad lineal en 5-m (s) (5-M) y 20-m shuttle run test (min) (20MSR) y de forma específica la prueba de agilidad específica en taekwondo (s) (TSAT) y la prueba de velocidad de frecuencia múltiple de patadas (FSKTMULT), específicamente el índice de disminución de patadas (FSKTMULT  KDI %) y el número máximo de patadas ejecutadas (FSKTMULT MAX). Resultados: Se documentó una relación grande significativa (p < 0,00) entre el %MG, la MG y la MM y la mayoría de las variables de rendimiento físico general analizadas. Relaciones grandes significativas (p < 0,05) se observaron entre %MG, la MG y la MM y la prueba TSAT. Una relación grande significativa se documentó entre la MM y FSKTMULT MAX (p<0,03) y entre la MG y FSKTMULT  KDI % (p<0,04). Correlaciones moderadas a bajas se observaron entre el PC y el IMC en la mayoría de las variables de rendimiento físico analizadas. Conclusiones: Los datos sugieren que un bajo %MG y MG seguido de una adecuada MM están relacionados con el rendimiento físico general específico en competidores chilenos de TKD de nivel nacional de ambos sexos

Morphodynamic change analysis of bedforms in the Lower Orinoco River, Venezuela

The Orinoco River has the third largest discharge in the world, with an annual mean flow of 37 600m3 s1 at its outlet to the Atlantic Ocean. Due to the presence of the Guiana Shield on the right bank, the lower reach of the Orinoco has a plan form characterized by contraction and expansion zones. Typical 1–1.5 km wide narrow reaches are followed by 7–8 km wide reaches. A complex pattern of bed aggradation and degradation processes takes place during the annual hydrological regime. A series of Acoustic Doppler Current Profiler (ADCP) transects were collected on an expansion channel in the Orinoco River, specifically over a fluvial island, representative of the lower Orinoco. In this study, temporal series of bathymetric cartography obtained by ADCP profiles combined with Differential Global Position System (DGPS) measurements (with dual-frequency), were used to recover the local displacement of bed forms in this island. The principal aims of this analysis were: (1) to understand the dynamics and evolution of sand waves and bars at this section and (2) to quantify the volume (erosion vs. accretion) of a mid-channel bar with dunes by applying DEM of Difference (DoD) maps on time series of bathymetric data. This required sampling with ADCP transects during the months of: May 2016; November 2016 and April 2017. Each bathymetric transect was measured twice, 1 day apart and on the same trajectory obtained by a GPS receptor. The spatial analysis of these ADCP transects is presented as a novel tool in the acquisition of time series of bathymetry for a relatively deep section ( 20 m) and under variable flow conditions