Estrategia de paso y frecuencia de ciclo en piragüismo en los JJ.OO. de Pekín

The objective of this study was to analyze the performance patterns from the world�s best paddlers who took part in the Beijing Olympic Games in 2008. The pacing strategy and the evolution of the cycle frequency were analysed from the official results and films recorded from broadcast TV. The analysis database included the 12 Olympics finals (500 and 1000 m). Evolution was similar in all events. The speed decreased through out both distances. There were no differences in pacing strategy between heats or semi-finals and finals. The cycle frequency had their higher values at the beginning of the finals, remained stable in 1000 m events, and decreased along the distance in 500 m events. In conclusion, pacing strategies and cycle frequency evolution followed a negative trend in all the Olympic races, and there were no significant differences in pacing strategy between heats or semi-finals and finals.El objetivo del estudio fue analizar la estrategia de paso y frecuencia de ciclo de los mejores palistas del mundo que participaron en los Juegos Olímpicos de Pekín 2008. Se analizó la estrategia de paso y la evolución de la frecuencia de ciclo de las doce pruebas incluidas en el programa olímpico (500 y 1000 m). La evolución de las variables analizadas fue similar en todas las pruebas. La velocidad disminuyó a lo largo de ambas distancias. No se encontraron diferencias significativas en la estrategia de paso entre eliminatorias y finales. La frecuencia de ciclo obtuvo sus mayores valores al inicio de las finales, permaneciendo estable en las pruebas de 1000 m y disminuyendo en las de 500 m. En conclusión, la estrategia de paso y la evolución de la frecuencia de ciclo respondieron a un patrón decreciente en todas las pruebas, sin diferencias significativas entre pruebas clasificatorias y finales

On weighted James' spaces

In this note we study the topological structure of weighted James spaces $J(h$). In particular we prove that $J(h)$ is isomorphic to $J$ if and only if the weight $h$ is bounded. We also provide a description of $J(h$) if the weight is a non-decreasing sequence

Effects of ketosis on cocaine-induced reinstatement in male mice;

In recent years, the benefits of the ketogenic diet (KD) on different psychiatric disorders have been gaining attention, but the substance abuse field is still unexplored. Some studies have reported that palatable food can modulate the rewarding effects of cocaine, but the negative metabolic consequences rule out the recommendation of using it as a complementary treatment. Thus, the main aim of this study was to evaluate the effects of the KD on cocaine conditioned place preference (CPP) during acquisition, extinction, and reinstatement. 41 OF1 male mice were employed to assess the effects of the KD on a 10 mg/kg cocaine-induced CPP. Animals were divided into three groups: SD, KD, and KD after the Post-Conditioning test. The results revealed that, while access to the KD did not block CPP acquisition, it did significantly reduce the number of sessions required to extinguish the drug-associated memories and it blocked the priming-induced reinstatement. © 2022 The Author(s

Prepulse Inhibition of the Startle Reflex as a Predictor of Vulnerability to Develop Locomotor Sensitization to Cocaine

Prepulse inhibition (PPI) of the startle reflex is a measure of sensory-motor synchronization. A deficit in PPI has been observed in psychiatric patients, especially those with schizophrenia and vulnerable subjects, since the neural bases of this disorder are also involved in the regulation of PPI. Recently, we have reported that baseline PPI levels in mice can predict their sensitivity to the conditioned reinforcing effects of cocaine in the conditioned place preference (CPP) paradigm. Mice with a low PPI presented a lower sensitivity to the conditioned rewarding effects of cocaine; however, once they acquired conditioned preference with a higher dose of the drug, a more persistent associative effect of cocaine with respect to environmental cues was evident in these animals when compared with High-PPI mice. Therefore, we proposed that the PPI paradigm can determine subjects with a higher vulnerability to the effects of cocaine. Developing locomotor sensitization after pre-exposure to cocaine is considered an indicator of transitioning from recreational use to a compulsive consumption of the drug. Thus, the aim of the present study was to evaluate whether subjects with a low PPI display a higher locomotor sensitization induced by cocaine. First, male and female OF1 mice were classified as High- or Low-PPI according to their baseline PPI levels. Subsequently, the motor effects induced by an acute dose of cocaine (Experiments 1 and 2) and the development of locomotor sensitization induced by pre-exposure to this drug (Experiments 3 and 4) were recorded using two apparatuses (Ethovision and actimeter). Low-PPI mice presented low sensitivity to the motor effects of an acute dose of cocaine, but a high increase of activity after repeated administration of the drug, thus suggesting a great developed behavioral sensitization. Differences after pretreatment with cocaine vs. saline were more pronounced among Low-PPI subjects than among High-PPI animals. These results endorse our hypothesis that the PPI paradigm can detect subjects who are more likely to display behaviors induced by cocaine and which can increase the risk of developing a cocaine use disorder. Herein, we further discuss whether a PPI deficit can be considered an endophenotype for cocaine use disorder

Percepción subjetiva del esfuerzo como herramienta en el control de la intensidad en la actividad de ciclismo indoor

A un total de 133 sujetos entre 22 y 64 años (38 hombres y 95 mujeres) pertenecientes a un centro deportivo privado, se les evaluó el porcentaje de la intensidad de la frecuencia cardiaca de reserva alcanzada y la percepción subjetiva del esfuerzo(RPE) durante una sesión real de ciclismo indoor. La intensidad media alcanzaday la RPE manifestada en la fase principal fue de 80,60 ± 6,74% (intensidad alta) y 15,11 ± 1,90 puntos (intensidad alta) en los hombres; y de 80,85 ± 7,54%(intensidad alta) y 15,49 ± 1,51 puntos (intensidad alta) en las mujeres (p > ,05). Se encontró una significativa y baja correlación entre la RPE y la FC media de reserva obtenida en la fase principal de la sesión (r= ,24; p < ,01). En conclusión, el ciclismo indoor es una actividad de alta intensidad. La RPE de Borg no es un instrumento válido para el control de la intensidad en esta actividad.One hundred and thirty-three subjects between 22 and 64 years old (38 males and 95 females) from a private sport centre participated in this study. Mean percentage heart rate intensity (%HRR) and overall ratings of perceived exertion (RPE) were measured during an indoor cycling session. Mean %HRR and RPE shown during the main phase were considered as high intensity in male and females. The correlation value between %HHR and overall RPE was low but significant. In conclusion, indoor cycling is a high-intensity activity. Borg's RPE is not a valid instrument for controlling the intensity of effort during indoor cycling activityA um total de 133 sujeitos entre 22 e 64 anos (38 homens e 95 mulheres) pertencentes a um centro desportivo privado, foi avaliada a percentagem da intensidade da frequência cardíaca de reserva (%FCR) alcançada e a percepção subjectiva do esforço (RPE) durante uma sessão real de ciclismo indoor. A intensidade média alcançada e a RPE manifestada na fase principal foi alta, tanto em homens como em mulheres. Foi verificada uma significativa e baixa correlação entre a RPE e a FC medida de reserva obtida na fase principal da sessão. Em conclusão, o ciclismo indoor é uma actividade de alta intensidade. A RPE de Borg não é um instrumento válido para o controlo da intensidade nesta actividade

Anthropometric and equipment characteristics in adolescent sprint kayakers

Los objetivos de este estudio fueron describir las características antropométricas y la configuración del material utilizado por 91 kayakistas españoles adolescentes de 13 y 14 años, de aguas tranquilas y buscar correlaciones entre ambas variables. Se valoraron las características antropométricas y las dimensiones del material de competición de noventa y un kayakistas de aguas tranquilas (45 hombres y 46 mujeres), de 13 y 14 años de edad. Los hombres kayakistas de 14 años presentaron valores superiores a los de 13 años en cuanto a dimensiones antropométricas y del material de competición, mientras que no se encontraron diferencias significativas entre las variables analizadas entre las mujeres kayakistas de 13 y 14 años. La talla y envergadura presentaron las mayores correlaciones con la longitud de la pala y la distancia asiento - reposapiés. La información aportada por este trabajo podría ser de utilidad para ajustar las dimensiones del material de competición, optimizando así el confort y rendimiento en kayakistas jóvenes.The aims of this study were to describe kinanthropometric characteristics and equipment set-up of male and female young kayakers and to look for correlations between both variables. Ninety one young sprint kayakers (45 males and 46 females), aged 13 and 14 years old, were assessed using a battery of 12 anthropometric and 5 equipment dimensions. Comparison between the 13- and 14-year-old kayakers showed that 14-year-old males had greater body and equipment dimensions than their 13-year-old counterparts, whereas there were no significant differences between 13- and 14-year-old female kayakers in both anthropometric and equipment set-up dimensions. Stretch stature and arm span were the variables which greater coefficient correlations showed with total paddle length and seat - feet bar distance. The data presented in this paper may provide important information to adjust equipment sep-up in order to optimise comfort and performance in young kayakers