El bucle de la internacionalización

Actividad Física y Deport

El momento de la verdad

Actividad Física y Deport

Adaptaciones cinemáticas, cinéticas, y antropométricas tras un entrenamiento de corta duración con arrastres de trineo en atletas entrenados

Introducción: el trabajo con arrastres de trineo es un método común de entrenamiento para la mejora del rendimiento en el sprint, tanto en la fase de aceleración como en la fase de máxima velocidad. Sin embargo, son pocos los trabajos de investigación que se han centrado en estudiar las adaptaciones al mismo en la fase de aceleración, o en la fase de máxima velocidad con sujetos entrenados. El objetivo del presente trabajo fue estudiar las adaptaciones cinemáticas, cinéticas y antropométricas tras un entrenamiento de cuatro semanas con arrastres de trineo en la fase de aceleración y de máxima velocidad del sprint, en atletas entrenados. Método: Veintidós atletas (8 mujeres y 14 hombres) de nivel nacional divididos en dos grupos participaron voluntariamente en el estudio. Se realizó un diseño cuasi-experimental intra e inter-sujetos con pre y post-test. Las variables objeto de estudio fueron de carácter cinemático, cinético, músculo-articular y antropométrico. Los sujetos realizaron una fase inicial de tres semanas de familiarización, integradas por dos sesiones de entrenamiento de musculación, combinado con otras dos sesiones de entrenamiento de velocidad y saltos. Tras esta fase, y después de dividir aleatoriamente la muestra en dos grupos denominados grupo experimental (GE) y grupo control (GC), dependiendo del tipo de entrenamiento realizado, se realizó una segunda fase de cuatro semanas de entrenamiento diferenciado. En esta segunda fase, los grupos realizaron dos sesiones semanales de velocidad y saltos, una sesión de regeneración y dos sesiones de musculación con altas cargas (10-8 RM¿s), la única diferencia en el entrenamiento fue que el GE realizaba las series de velocidad arrastrando un trineo que producía el 7.5% de pérdida de la máxima velocidad. Al inicio y al final de las 4 semanas de entrenamiento específico, los atletas realizaron los siguientes test: sprints a máxima intensidad sobre 50 m con salida de tacos, tomando el tiempo en intervalos de 15 m, 30 m y 50 m; test de salto vertical: salto en sentadilla con un ángulo de 90º (SJ) y de 120º (SJM), salto con contramovimiento (CMJ) y salto con caída de 50 cm (DJ); una repetición máxima (1-RM) y potencia (POW) al 30%, 45%, 60%, 70% y 80% de 1-RM en media sentadilla; y fuerza isocinética concéntrica (FIC) de los flexores y extensores de la cadera a velocidades de 60º¿ s-1, 180º¿ s-1, 270º¿ s-1 y 450º¿ s-1. Se realizó un estudio fotogramétrico de la técnica de carrera en la fase de aceleración (tres primeras zancadas) en el instante de contacto (Tdown) y de despegue (Toff), y de la fase de máxima velocidad (45 m) en los instantes Tdown, apoyo medio (Tmid) y Toff. También se realizó un estudio antropométrico. Para conocer las diferencias intra-grupos se realizó un T-test para muestras relacionadas. Para determinar las diferencias inter-grupos se realizó un T-test para muestras independientes. Resultados: en el GE se observaron diferencias estadísticamente significativas en: la disminución del tiempo y el aumento de la velocidad media en la fase de transición (15-30 m); el aumento de la inclinación del tronco en Tdown en la fase de aceleración, el aumento de la amplitud de zancada y de la distancia de aterrizaje, además de diferentes variables cinemáticas relacionadas en Tdown y Tmid, en la fase de máxima velocidad; el aumento de la 1-RM y POW al 45% y 70% de 1-RM; la mejora de la FIC de los flexores de cadera a 180º¿ s-1 y 270º¿ s-1 en valores absolutos y a 180º¿ s-1 relativos al PC; así como un incremento en la fuerza máxima aplicada durante los primeros 100 ms desde el comienzo del SJM. En el GC se produjeron las siguientes modificaciones estadísticamente significativas: una disminución del tiempo y un aumento en la velocidad media en la fase de máxima velocidad (30-50 m); en la fase de aceleración, un incremento en la velocidad angular de la rodilla libre, en la fase de máxima velocidad, una disminución de los tiempos de contacto y un aumento en la inclinación de tronco en Tmid, además de diferentes modificaciones cinemáticas relacionadas con dichas variables en los tres instantes; una mejora de la 1-RM y la potencia al 30% de 1-RM; un incremento de la FIC de los flexores de cadera en todas las velocidades, para los valores absolutos, y a las velocidades de 60º¿ s-1 y 180º¿ s-1 relativos al PC; una mejora de la potencia pico al realizar un SJM; así como una tendencia a la significación en la rigidez vertical (p = 0.081). Tan sólo se han encontrado diferencias estadísticamente significativas inter-grupos para las variables tiempo de contacto y fuerza máxima aplicada durante los primeros 100 ms desde el comienzo del SJM. Discusión: los resultados parecen indicar que el GE mejora el rendimiento en la fase de transición, mientras que el GC lo mejora en la fase de máxima velocidad. El entrenamiento resistido produce una mejora en la 1-RM que junto a las modificaciones en la configuración del atleta en las distintas fases (aumento de la distancia de aterrizaje, acompañado de un aumento de la amplitud de zancada) orienta las mejoras hacia un incremento en el rendimiento en la fase de transición del sprint. El entrenamiento del GC, además de mejorar la 1-RM, produce mejoras en la rigidez vertical, por un posible aumento de la coordinación inter-muscular. Este incremento influye positivamente en la reducción de los tiempos de contacto, que inciden de forma directa en un aumento en el rendimiento de la fase de máxima velocidad del sprint. Conclusiones: el entrenamiento a corto plazo con entrenamiento resistido en atletas entrenados produce adaptaciones cinemáticas y cinéticas similares a las del GC. Sin embargo, el reflejo a corto plazo en el rendimiento es diferente. El GE lo mejora en la fase de transición, mientras que el GC lo mejora en la fase de máxima velocidad. Estas mejoras se producen por un aumento de la amplitud de zancada en el GE, y un descenso de los tiempos de contacto y un aumento de la rigidez vertical en el GC.Actividad Física y DeporteTerapia y Rehabilitació

Effects of different amplitudes (high vs. low) of whole-body vibration training in active adults

The aim of this study was to evaluate the effects of two different amplitudes of whole-body vibrations on the development of strength, mechanical power of the lower limb, and body composition. Thirty-eight recreationally active participants took part in the study. Participants were divided in two experimental groups (low amplitude group [GL] = 2 mm; high amplitude group [GH] = 4 mm) and a control group. The experimental groups performed an incremental vibratory training, 2 days per week during 6 weeks. The frequency of vibration (50 Hz), time of work (60 seconds), and time of rest (60 seconds) were constant for GL and GH groups. All the participants were on the platform in a static semi-squat position. Maximum isokinetic strength, body composition, and performance in vertical jumps (squat and countermovement jumps) were evaluated at the beginning and at the end of the training cycle. A significant increase of isokinetic strength was observed in GL and GH at angular velocities of 60°·s-1, 180°·s-1 and 270°·s-1. Total lean mass was significantly increased in GH (0.9 ± 1.0 kg). There were no significant changes in the total fat mass in any of the groups. Significant changes were not observed in different variables (height, peak power, and rate of force development) derived from the vertical jumps for any of the groups submitted to study. The vibration training, whatever the amplitude, produced significant improvements in isokinetic strength. However, high vibration amplitude training presents better adaptations for hypertrophy than the training with low vibration amplitude. In this sense, GH would be a better training if the practitioners want to develop both strength and hypertrophy of the lower limbs.Actividad Física y Deport

Effects of 24 Weeks of Whole Body Vibration Versus Multicomponent Training on Muscle Strength and Body Composition in Postmenopausal Women: A Randomized Controlled Trial.

The purposes of this study were to analyze the impact of 24 weeks of vibratory and multicomponent training (MT) and to determine what type of training creates greater adaptations on body composition and isokinetic strength of the knee and ankle joints in postmenopausal women. Thirty-eight women (60.0 ± 6.3 years) were randomly assigned to whole body vibration group (WBVG), multicomponent training group (MTG), or a control group. A significant decrease in total fat mass was observed in experimental groups. There were no changes in total lean mass and total bone mineral density in both groups. WBVG and MTG showed significant increases in isokinetic strength for knee extensors at 60°/s and at 270°/s. Regarding the ankle joint, there were significant increments in strength for plantar flexion at 60°/s in WBVG and at 120°/s in the two trainings groups. MTG showed a significant increase in strength for dorsiflexion at 60°/s. With respect to eversion and inversion, WBVG and MTG improved strength at 60°/s. Also, the WBVG showed increased strength in the ankle evertors at 120°/s and both groups showed increased strength in the ankle invertors at 120°/s. Twenty-four weeks of whole body vibration or MTs result in positive modifications in total fat mass. These trainings are effective in improving knee extension and stabilizer muscles of the ankle joint strength.Actividad Física y Deport

Regular consumption of HolisFiit, a polyphenol-rich extract-based food supplement, improves mind and body well-being of overweight and slightly obese volunteers: a randomized, double-blind, parallel trial.

Modern lifestyles face growing demands for natural solutions to help improve general well-being. Accordingly, mind-body activities such as yoga have considerably grown. However, beneficial effects require regular workout. Besides, literature suggests that polyphenols may demonstrate positive effects on both mental and physical health. Overweight and obese volunteers, for which well-being might be perceived degraded, were included in a 16-week double-blind, randomized and parallel trial with a daily supplementation of HolisFiit®, a polyphenol-rich food supplement. Body composition was assessed by dual-energy X-ray absorptiometry (DXA) technology; well-being was evaluated with both, Athens Insomnia Scale (AIS) and components from Short Form-36 questionnaire (SF-36). Body composition significantly rebalanced by 7.7% (p = .019) of the lean-to-fat mass ratio. Also, sleep quality significantly improved by 43% (p = .00015) as well as both physical and mental components from SF-36, respectively by 10% (p = .004) and 7% (p = .021). These data altogether, suggest that regular consumption of HolisFiit®, might significantly improve mind and body well-being.Actividad Física y Deport

Kinematic, strength, and stiffness adaptations after a short-term sled towing training in athletes

One of the most frequently used methods for training the sprint‐specific strength is the sled towing. To date, no studies have been conducted to explore the effects of this method after a training period in well‐trained athletes. The purpose of this study was to determine the effects of 4 weeks of resisted sprint training with sled towing. Twenty‐two trained athletes experienced in the use of weighted sled (WS) participated in the study. They conducted the same 3‐week training to level their initial condition. After that they were distributed in two groups, unresisted (UR) and WS training. They carried out the same 4‐week, 2 days/week sprint‐specific training, only differing in that the experimental group performed sprints with a (WS) which caused a reduction of 7.5% of their maximum velocity. Pre‐ and posttest were conducted which included the measurement of sprint kinematics, muscular strength (including isoinertial, isokinetic, and jump measurements), and sprinting stiffness (leg and vertical). Results show different adaptations in the groups although no interaction effect was found. The WS group improved the velocity in the transition phase, while the UR group improved the velocity in the maximum velocity phase. No improvements in the height of the jump tests were found.Actividad Física y Deport

Acute Effects of Two Different Resistance Circuit Training Protocols on Performance and Perceived Exertion in Semiprofessional Basketball Players

Acute effects of two different resistance circuit training protocols on performance and perceived exertion in semiprofessional basketball players. J Strength Cond Res 30(2): 407–414, 2016—This study aimed to investigate the acute effects of two different resistance circuit training protocols on basketball players' physical and technical performance and rating of perceived exertion (RPE). In a repeated-measures, crossover experimental design, 9 semiprofessional basketball players performed a Power Circuit Training (PCT; 45% 1RM) and a High-Resistance Circuit Training (HRC; 6RM), on consecutive weeks. Vertical and horizontal jump performance, 3-points shooting accuracy, repeated-sprint ability (RSA), agility, and upper body power output were measured before and after training. The RPE was assessed 20 minutes after resistance training. One-way repeated-measures analysis of variance showed performance decrements in vertical jump height and peak power, horizontal jump distance, 3-points percentage, bench-press power output, RSA total and ideal time, and agility T-Test at total time following HRC, but not PCT (p <= 0.05). The RPE was higher in HRC compared with PCT. The results of this study indicated that HRC was perceived as being harder and produced higher fatigue levels, which in turn lowered acute performance. However, low-to-moderate intensity loads did not negatively affect performance. Thus, completing a PCT session may be the most appropriate option before a practice or game as it avoids acute–resistance–training-induced performance decrements. However, if the objective of the basketball session is to develop or perfect technical skills during fatiguing conditions, HRC may be the more suitable option.Actividad Física y Deport

Power-strength curve in basketball players

The purpose of this study was to examine the power-strength curve in a half squat exercise in trained basketball players of the EBA league. For that, a cross sectional, descriptive study was carried out to 8 high-level male basketball players. After controlling the participants 1RM, a progressive test, consisted on moving loads of 30, 45, 60, 70 and 80% of 1RM as fast as possible in the concentric phase, was performed. The participants showed the highest peak power output with loads of 45% of 1RM. These results differ from the wide literature, which shows values ranged between 30% and 70% of 1RM; this can be due to: a) the analyzed sample; b) the experience of the participants; and c) the methodology used for the record. Therefore, we concluded that, the basketball players studied present values of peak power output, in competitive period, near to 45% of 1RM in the half squat exercise

Effects of whole-body vibration training on body composition and physical fitness in recreationally active young adults

In the last decade, it has been suggested that whole- body vibration training (WBV) may increase neuromuscular performance and consequently affect the muscular improvement as either acute response to vibration or chronic adaptation training. Vibrating platforms generate frequencies from 5-45 Hz and vertical oscillations of 1-11 mm peak to peak, affecting more or less intensity acceleration changing by combining frequency and amplitude. Vibration training, in a session as various offers different results in regard to changes in body composition and in increasing the vertical jump, sprint, and the different manifestations of force development. These promising results await further research to establish parameters (duration, frequency and amplitude) with vibration stimulation in young active subjects. This literature review provides an update on the scientific evidence on the body vibrations in order to answer the question whether WBV, meaning the exercise by increasing the gravitational load collection, is a treatment option if the aim is to improve neuromuscular function, flexibility, balance, agility, coordination and body composition.In the last decade, it has been suggested that whole-body vibration training (WBV) may increase neuromuscular performance and consequently affect the muscular improvement as either acute response to vibration or chronic adaptation training. Vibrating platforms generate frequencies from 5-45 Hz and vertical oscillations of 1-11 mm peak to peak, affecting more or less intensity acceleration changing by combining frequency and amplitude. Vibration training, in a session as various offers different results in regard to changes in body composition and in increasing the vertical jump, sprint, and the different manifestations of force development. These promising results await further research to establish parameters (duration, frequency and amplitude) with vibration stimulation in young active subjects. This literature review provides an update on the scientific evidence on the body vibrations in order to answer the question whether WBV, meaning the exercise by increasing the gravitational load collection, is a treatment option if the aim is to improve neuromuscular function, flexibility, balance, agility, coordination and body composition.Actividad Física y Deport