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This study aimed to compare the external peak physical demands (PDs) of under-19-year-old (U19) and professional male football players according to playing position. Positional data derived from Global Positioning System (GPS) tracking during 15 matches in the 2023/24 season for both groups were analyzed. The following variables were measured: total distance, high-intensity running distance, sprint distance, acceleration count, and high-intensity actions. A linear mixed-effects model was employed, with category and playing position included as fixed effects to compare these metrics at the player level. The results revealed only a few significant differences in physical demands between the U19 and professional players. Notably, central defenders and central midfielders exhibited lower performance in HSR distance compared to other positions, with the professional players registering higher values than their U19 counterparts. However, no significant differences were observed for total and relative sprint distances, the number of accelerations, high intensity and relative sprint running efforts. These findings highlight the overall similarity in physical demands between U19 players and professional players, suggesting that elite youth athletes may be adequately prepared to meet the physical challenges of professional competition, with the exception of HSR distance. These conclusions have practical implications for coaches and performance staff, supporting the development of position-specific training programs, optimizing workload management through GPS monitoring, improving microcycle planning, and enhancing injury prevention strategies.

The horizontal and vertical distribution and the dorsal mantle length (DML) of the jumbo squid (Dosidicus gigas) were investigated in the Gulf of California during March and September-October 2010 using a Simrad EY-60 echo-sounder (120 kHz split beam transducer) and jig sampling. During March jumbo squids were captured and echo-detected off Santa Rosalia and around and south of the Grandes Islas region, in regions where satellite sea surface temperatures ranged between 16.5 and 18 degree C. Jumbo squid were also abundant south of Guaymas Basin and along the east coast with SST ranged between 17.5 and 19 degree C. During September-October jumbo squids were echo detected and captured at the west coast of the gulf at regions with SST below the mean of the survey area (< 30.5 degree C). Jumbo squid distribution and DML estimated using hydroacoustic methods and measured from captured squids followed the previously known seasonal migrations and temporal DML frequency distribution reported in the Gulf, in the Grandes Islas region and east coast of the Gulf during the spring and in the east coast during late summer. Hydroacoustic data showed no daily vertical migrations during the two sampling seasons.Original Abstract: Se estudio la distribucion horizontal y vertical y la estructura de longitud del manto (LM) del calamar gigante (Dosidicus gigas) recolectados en el Golfo de California durante marzo y septiembre-octubre del 2010, mediante una prospeccion acustica (ecosonda Simrad EY-60; 120 kHz de frecuencia, de haz dividido) y captura de calamares con poteras. Durante marzo, los calamares fueron eco detectados y capturados con poteras en la zona de las Grandes Islas, donde la temperatura superficial (TSM) detectada por satelite, registro un intervalo entre 16.5 y 18 degree C. Los calamares fueron abundantes ademas al sur de la Cuenca de Guaymas y a lo largo de la costa este del golfo, en aguas con TSM entre 17.5 y 19 degree C. Durante septiembre-octubre los calamares fueron eco detectados y capturados a lo largo de la costa oeste del golfo, en regiones con TSM por debajo de la media del area muestreada (<30.5 degree C). La distribucion horizontal y las estimaciones de LM realizadas con metodos de hidroacustica y capturados con poteras, concuerdan con los modelos de migracion estacional y de distribucion de frecuencias de LM previamente reportados en el golfo: principalmente distribuidos en las Grandes Islas y costa este del golfo en primavera, y en la costa este durante el final del verano. Los datos hidroacusticos no mostraron evidencia de migracion vertical diaria en ninguna de las dos epocas del ano estudiadas.