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The aim of this investigation was to determine the effect of a moderate dose of caffeine (3 mg/kg/b.m.) on muscular power and strength and shot put performance in trained athletes. Methods. Thirteen shot putters (eight men and five women) participated in a double-blind, placebo-controlled, randomized experiment. In two different trials, participants ingested either 3 mg/kg/b.m. of caffeine or a placebo. Forty-five min after substance ingestion, athletes performed a handgrip dynamometry test, a countermovement jump (CMJ), a squat jump (SJ), and a maximum-velocity push-up. The athletes also performed three types of throws: a backwards throw, a standing shot put and a complete shot put. Results. In comparison with the placebo, caffeine ingestion increased CMJ height (32.25 ± 7.26 vs. 33.83 ± 7.72 cm, respectively; effect size (ES) = 0.82, p = 0.012; +5.0%;) and SJ height (29.93 ± 7.88 vs. 31.40 ± 7.16 cm; ES = 0.63, p = 0.042; +6.4%) and distance in the standing shot put (10.27 ± 1.77 m vs. 10.55 ± 1.94 m; ES = 0.87, p = 0.009; +2.6%). However, caffeine ingestion did not increase strength in the handgrip test, power in the ballistic push-up, or distance in the backwards throw (all p > 0.05). Shot put performance changed from 11.24 ± 2.54 to 11.35 ± . 2.57 m (ES = 0.33, p = 0.26; +1.0%), although the difference did not reach statistically significant differences. Caffeine ingestion did not increase the prevalence of side effects (nervousness, gastrointestinal problems, activeness, irritability, muscular pain, headache, and diuresis) in comparison with the placebo (p > 0.05). Conclusion. In summary, caffeine ingestion with a dose equivalent to 3 mg/kg/b.m. elicited moderate improvements in several aspects of physical performance in trained shot putters but with a small effect on distance in a complete shot put.

Previous research has identified acute caffeine intake as an effective ergogenic aid to enhance velocity and power during bench press exercise. However, no previous investigation has analyzed the effects of chronic intake of caffeine on training adaptations induced by bench press strength training. Thus, the aim of this investigation was to determine the effects of pre-exercise caffeine intake on training adaptations induced by a bench press training protocol. Using a double-blind, randomized experimental design, 16 healthy participants underwent a bench press training protocol for 4 weeks (12 sessions). Seven participants ingested a placebo and nine participants ingested 3 mg/kg/BM of caffeine before each training session. Three days before, and 3 days after the completion of the training protocol, participants performed a one-repetition maximum (1RM) bench press and force-velocity test (from 10 to 100% 1RM). From comparable pre-training values, the strength training similarly increased 1RM in the caffeine and placebo groups (+13.5 ± 7.8% vs. +11.3 ± 5.3%, respectively; p = 0.53). In the caffeine group, the strength training induced a higher mean velocity at 40%, (0.81 ± 0.08 vs. 0.90 ± 0.14 m/s), 60% (0.60 ± 0.06 vs. 0.65 ± 0.06 m/s), 70% (0.47 ± 0.05 vs. 0.55 ± 0.06 m/s), 80% (0.37 ± 0.06 vs. 0.45 ± 0.05 m/s), 90% (0.26 ± 0.07 vs. 0.34 ± 0.06 m/s), and 100% 1RM (0.14 ± 0.04 vs. 0.25 ± 0.05 m/s; p < 0.05) while the increases in the placebo group were evident only at 30 (0.95 ± 0.06 vs. 1.03 ± 0.07 m/s), 70% (0.51 ± 0.03 vs. 0.57 ± 0.05 m/s) and 80% 1RM (0.37 ± 0.06 vs. 0.45 ± 0.05 m/s) (p < 0.05). The placebo group only increased peak velocity at 60 and 70% 1RM (p < 0.05) while peak velocity increased at 10%, and from 30 to 100% 1RM in the caffeine group (p < 0.05). The use of 3 mg/kg/BM of caffeine before exercise did not modify improvements in 1RM obtained during a 4 week bench press strength training program but induced more muscle performance adaptations over a wider range of load.

The ergogenic effect of acute caffeine ingestion has been widely investigated; however, scientific information regarding tolerance to the performance benefits of caffeine, when ingested on a day-to-day basis, is scarce. The aim of this investigation was to determine the time course of tolerance to the ergogenic effects of a moderate dose of caffeine. Eleven healthy active participants took part in a cross-over, double-blind, placebo-controlled experiment. In one treatment, they ingested 3 mg/kg/day of caffeine for 20 consecutive days while in another they ingested a placebo for 20 days. Each substance was administered daily in an opaque unidentifiable capsule, and the experimental trials started 45 min after capsule ingestion. Two days before, and three times per week during each 20-day treatment, aerobic peak power was measured with an incremental test to volitional fatigue (25 W/min) and aerobic peak power was measured with an adapted version of the Wingate test (15 s). In comparison to the placebo, the ingestion of caffeine increased peak cycling power in the incremental exercise test by ~4.0 ±1.3% for the first 15 days (P

The aim of this investigation was to analyze the influence of the genetic variations of the -163C>A polymorphism of the CYP1A2 gene on the ergogenic effects of caffeine in elite basketball players.Nineteen elite basketball players (10 men and 9 women) ingested 3 mg⋅kg-1 of caffeine or a placebo 60 min before performing 10 repetitions of the following series: the Abalakov jump test followed by the Change-of-Direction and Acceleration Test (CODAT). The players then competed in a 20-min simulated basketball game. Self-perceived performance and side effects were recorded by questionnaires after the trials. The effects of caffeine on basketball performance were established according to players' CYP1A2 genotype (rs762551): AA homozygotes (n = 10) and C-allele carriers (n = 9).In the 10 repetitions, caffeine increased Abalakov jump height by a mean of 2.9±3.6% in AA homozygotes (p = 0.03) while this effect did not reach statistical significance for C-allele carriers (2.3 ± 6.8%; p = 0.33). Caffeine did not affect sprint time in the CODAT test in either genotype group but it increased the number of impacts performed during the simulated game in both AA homozygotes (4.1 ± 5.3%; p = 0.02) and C-allele carriers (3.3 ± 3.2%; p = 0.01). During the 24 h following the test, AA homozygotes tended to experience increased insomnia with caffeine while C-allele carriers did not present this effect. The remaining variables were unaffected by the genotype.The CYP1A2 -163C>A polymorphism minimally altered the ergogenicity derived from the consumption of a moderate dose of caffeine in elite basketball players.

El objetivo de este trabajo es valorar si se produce el efecto de la edad relativa en el fútbol profesional en España, equipos filiales y sus categorías inferiores, donde el corte de edad actual para la formación de las diferentes categorías es el del año natural. El análisis ha incluido a todos los futbolistas de la primera división española de la temporada 2009-2010, así como a 16 equipos filiales y a la cantera de 11 de estos equipos (total N=2.116). El resultado de nuestro estudio confirma un efecto de la edad relativa en todos los grupos, con un descenso significativo desde las categorías inferiores hasta los equipos filiales y la primera división. Se hace patente replantear los sistemas de competición y la detección de talentos de cara a evitar este sesgo que limita las posibilidades de los deportistas nacidos en los últimos meses del año.

PURPOSE:Exertional rhabdomyolysis can occur in individuals performing various types of exercise but it is unclear why some individuals develop this condition while others do not. Previous investigations have determined the role of several single nucleotide polymorphisms (SNPs) to explain inter-individual variability of serum creatine kinase (CK) concentrations after exertional muscle damage. However, there has been no research about the interrelationship among these SNPs. The purpose of this investigation was to analyze seven SNPs that are candidates for explaining individual variations of CK response after a marathon competition (ACE = 287bp Ins/Del, ACTN3 = p.R577X, CKMM = NcoI, IGF2 = C13790G, IL6 = 174G>C, MLCK = C37885A, TNFα = 308G>A). METHODS:Using Williams and Folland's model, we determined the total genotype score from the accumulated combination of these seven SNPs for marathoners with a low CK response (n = 36; serum CK

ResumenLa figura del entrenador de alto nivel (E.A.N.) en triatlón y su entorno apenas ha sido estudiada, y sin embargo puede estar ejerciendo una gran influencia sobre el microsistema deportivo. Estudiar este microsistema es el objetivo del presente estudio en función de los siguientes factores: interacción con sus deportistas, objetivos deportivos, grado de satisfacción con diferentes agentes del entorno (triatletas, otros entrenadores, federaciones y club), ámbito laboral, nivel académico y entorno familiar. Además, se pretende conocer qué cualidades atribuibles a un buen entrenador de alto nivel en triatlón son las mejores valoradas por los propios entrenadores. En este estudio participan 14 entrenadores españoles de alto nivel en activo (uno menos que el universo de la muestra objeto). Todos ellos hombres (edad media= 37,43 años ±7,27). El diseño de investigación descriptivo-cuantitativo utiliza el cuestionario como instrumento. El cuestionario fue pasado en periodo no competitivo por el mismo investigador mediante entrevistas personales mayoritariamente, o de forma telemática en su defecto. Los resultados muestran que el triatlón de alto nivel español se rige por un sistema centralizado en centros de rendimiento. La presencia del entrenador en las competiciones (sólo uno acudía a todas) no supone un factor determinante del rendimiento. El ratio número de atletas de alto nivel por entrenador es de 3,71(+3,04) y el ratio total contando con otros triatletas de diferente nivel es de 8 (±4,78), adecuado para las condiciones actuales pero mejorable en el alto nivel. El nivel académico de los E.A.N. es muy bueno y específico a su labor deportiva. La cualidad confianza para el diálogo personal (4,69 sobre 5) resulta ser la más valorada por parte de los propios entrenadores, anteponiendo el plano personal al deportivo.AbstractNot much attention has been paid to the high level coach (H.L.C.) in triathlon and his environment; however this one could be influencing the sport microsystem. The aim of the present study is to describe this microsystem. The assessed factors are: interaction coach-athletes, sports goals, satisfaction with various environmental agents (triathletes, other coaches, federations and club), workplace, academic level and family environment. In addition, a number of qualities associated with a successful coaching are valued.Participants are 14 H.L.C. on active service out of a universal sample of 15 in high level Spanish triathlon. All of them are males (average age= 37,43 years old ±7,27). Using the questionnaire, the research follows a quantitative and descriptive design. The personal interviews were carried by the same researcher in the preparatory period. The results show Spanish high level triathlon as a sports system centralized in centers of performance for triathletes. Triathlon nature and coaches’ environment do not make their presence in the competition be determinant in athlete’s performance (only one coach was present in all competitions). The ratio number of elite athletes / coach is 3.71 (± 3.04), and total count ratio between athletes of different levels is 8 (± 4.78). This is a suitable number for current conditions, but it could be improvable in high level conditions. Coaches’ academic level is very good and it is specific to their profession.Confidence in personal interaction (4,69 over 5) proves to be the most valued factor by the H.L.C. In this sense, they consider the personal sphere to be more relevant than sports sphere.doi:10.5232/ricyde2011.02304

El principal objetivo del presente estudio es posicionar a las Comunidades Autónomas españolas en función de sus ofertas de instalaciones deportivas, utilizando para ello los datos proporcionados por el Censo Nacional de Instalaciones Deportivas-2005. El universo de estudio estuvo formado por todas las instalaciones y espacios deportivos que se censaron en España a lo largo de 2005. Para proceder al posicionamiento de las Comunidades se seleccionaron y definieron 15 variables por parte de un grupo de expertos. Dichas variables se agruparon en tres Indicadores Parciales (Población, Calidad y Densidad) y su sumatorio dio lugar a un Indicador Sintético de Instalaciones Deportivas (ISID), que permitió posicionar de manera global a las Comunidades según sus respectivas ofertas de instalaciones. Los resultados del ISID ponen de manifiesto que en España existen importantes desigualdades territoriales en la distribución de la oferta de instalaciones deportivas. Asimismo, los resultados obtenidos en este estudio también parecen indicarque las Comunidades mejor posicionadas en los Indicadores Población y/o Densidad suelen presentar mayores tasas de práctica deportiva entre sus habitantes, mientras que las peor posicionadas en dichos Indicadores tienden a mostrar menores niveles de práctica.

La juventud del triatlón como deporte trasgresor e innovador, alcanza también al ámbito de la investigación, pues es difícil encontrar estudios dentro de las áreas de la sociología y la psicología social, situadas entre la explicación elemental y la integral, en las cuales se centra nuestra investigación. El grueso de los estudios en triatlón se dirige a los aspectos fisiológicos y antropométricos, sin embargo, el éxito deportivo trasciende el plano netamente físico, y atiende a otros factores como la dedicación y capacidad de implicación del deportista así como las influencias que le rodean, es decir, del “entorno próximo”, que ocupa el núcleo del sistema deportivo desde una concepción en esferas concéntricas. Nos centramos por tanto en el microsistema. Pretendemos pues abrir una nueva vía que nos ofrezca información sobre la población de triatletas españoles, quiénes son y cuáles son sus inquietudes y motivaciones, con el fin de mejorar el sistema partiendo desde una base empírica construida a través de las necesidades reales de los protagonistas de nuestro deporte, de los cuales se ha extraído un perfil sociodemográfico.

La natación recreativa es la actividad físico-deportiva con mayor volumen de practicantes en España. Esta actividad se ha visto favorecida en los últimos años por el progresivo incremento de la oferta de piscinas cubiertas, siendo este espacio el que presenta mayor intensidad de uso. Distintos estudios han destacado la asociación positiva entre la disponibilidad de nstalaciones deportivas y los niveles de actividad física de la población. El análisis cuantitativo y cualitativo de la oferta de piscinas cubiertas en las Comunidades Autónomas puede resultar un excelente indicador del grado de desarrollo de estas instalaciones en la consecución de un entorno social más saludable. Para ello, se seleccionaron 12 variables por un grupo de expertos que permitieran el análisis de la oferta de piscinas cubiertas en las regiones, y mediante el análisis con un Indicador Sintético de Piscinas Cubiertas (ISPC) se clasificó a las Comunidades Autónomas en 4 niveles de desarrollo (Bajo, Medio-Bajo, Medio- Alto y Alto). Los resultados ofrecen una gran disparidad entre las regiones en sus dotaciones de piscinas cubiertas, fruto de las diferentes inversiones políticas, culturas deportivas y realidades sociales, situándose en los primeros puestos las Comunidades Autónomas con mayor práctica deportiva. Este estudio puede servir de herramienta para una mejor planificación deportiva de las Autonomías y entidades promotoras del deporte.

Myosin light chain kinase (MLCK) phosphorylates the regulatory light chain (RLC) of myosin producing increases in force development during skeletal muscle contraction. It has been suggested that MLCK gene polymorphisms might alter RLC phosphorylation thereby decreasing the ability to produce force and to resist strain during voluntary muscle contractions. Thus, the genetic variations in the MLCK gene might predispose some individuals to higher values of muscle damage during exercise, especially during endurance competitions. The aim of this investigation was to determine the influence of MLCK genetic variants on exercise-induced muscle damage produced during a marathon. Sixty-seven experienced runners competed in a marathon race. The MLCK genotype (C37885A) of these marathoners was determined. Before and after the race, a sample of venous blood was obtained to assess changes in serum myoglobin concentrations and leg muscle power changes were measured during a countermovement jump. Self-reported leg muscle pain and fatigue were determined by questionnaires. A total of 59 marathoners (88.1%) were CC homozygotes and 8 marathoners (11.9%) were CA heterozygotes. The two groups of participants completed the race with a similar time (228 ± 33 vs 234 ± 39 min; P = 0.30) and similar self-reported values for fatigue (15 ± 2 vs 16 ± 2 A.U.; P = 0.21) and lower-limb muscle pain (6.2 ± 1.7 vs 6.6 ± 1.8 cm; P = 0.29). However, CC marathoners presented higher serum myoglobin concentrations (739 ± 792 vs 348 ± 144 μg·mL-1; P = 0.03) and greater pre-to-post- race leg muscle power reduction (-32.7 ± 15.7 vs -21.2 ± 21.6%; P = 0.05) than CA marathoners. CA heterozygotes for MLCK C37885A might present higher exercise-induced muscle damage after a marathon competition than CC counterparts.

[This corrects the article DOI: 10.1371/journal.pone.0160053.].

En este trabajo se analizaron las relaciones entre la orientación motivacional y otros aspectos de la práctica deportiva en cuatro clubes de karate de nivel competitivo. 49 deportistas respondieron a los diferentes cuestionarios administrados. Los resultados mostraron una relación entre la orientación motivacional de los deportistas y los siguientes factores: el clima motivacional percibido en su entorno, la competencia motriz percibida, las atribuciones del éxito en el deporte, la diversión con la práctica deportiva, el compromiso y entrega en el aprendizaje y la ansiedad ante el error y las situaciones de estrés. La orientación al ego correlacionó con un clima motivacional percibido al ego en padres, entrenador y compañeros, con una mayor competencia motriz percibida, con la habilidad normativa y el engaño como medios de alcanzar el éxito en el deporte, y con el aburrimiento. La orientación a la tarea correlacionó con la motivación-esfuerzo como forma de alcanzar el éxito deportivo, con la diversión con la práctica deportiva, la ansiedad ante las situaciones de estrés y con un menor compromiso y entrega en el aprendizaje.

The aim of this study was to investigate the relationship between changes in serum free amino acids, muscle fatigue and exercise-induced muscle damage during a half-ironman triathlon. Twenty-six experienced triathletes (age = 37.0 ± 6.8 yr; experience = 7.4 ± 3.0 yr) competed in a real half-ironman triathlon in which sector times and total race time were measured by means of chip timing. Before and after the race, a countermovement jump and a maximal isometric force test were performed, and blood samples were withdrawn to measure serum free amino acids concentrations, and serum creatine kinase levels as a blood marker of muscle damage. Total race time was 320 ± 37 min and jump height (-16.3 ± 15.2%, P < 0.001) and isometric force (-14.9 ± 9.8%; P = 0.007) were significantly reduced after the race in all participants. After the race, the serum concentration of creatine kinase increased by 368 ± 187% (P < 0.001). In contrast, the serum concentrations of essential (-27.1 ± 13.0%; P < 0.001) and non-essential amino acids (-24.4 ± 13.1%; P < 0.001) were significantly reduced after the race. The tryptophan/BCAA ratio increased by 42.7 ± 12.7% after the race. Pre-to-post changes in serum free amino acids did not correlate with muscle performance variables or post-race creatine kinase concentration. In summary, during a half-ironman triathlon, serum amino acids concentrations were reduced by > 20%. However, neither the changes in serum free amino acids nor the tryptophan/BCAA ratio were related muscle fatigue or muscle damage during the race.

BACKGROUND: Completing a marathon is one of the most challenging sports activities, yet the source of running fatigue during this event is not completely understood. The aim of this investigation was to determine the cause(s) of running fatigue during a marathon in warm weather. METHODOLOGY/PRINCIPAL FINDINGS: We recruited 40 amateur runners (34 men and 6 women) for the study. Before the race, body core temperature, body mass, leg muscle power output during a countermovement jump, and blood samples were obtained. During the marathon (27 °C; 27% relative humidity) running fatigue was measured as the pace reduction from the first 5-km to the end of the race. Within 3 min after the marathon, the same pre-exercise variables were obtained. RESULTS: Marathoners reduced their running pace from 3.5 ± 0.4 m/s after 5-km to 2.9 ± 0.6 m/s at the end of the race (P 15% pace reduction) had elevated post-race myoglobin (1318 ± 1411 v 623 ± 391 µg L(-1); P

BackgroundThe negative effects of dehydration on aerobic activities are well established. However, it is unknown how dehydration affects intermittent sports performance. The purpose of this study was to identify the level of dehydration in elite badminton players and its relation to muscle strength and power production.MethodologySeventy matches from the National Spanish badminton championship were analyzed (46 men's singles and 24 women's singles). Before and after each match, jump height and power production were determined during a countermovement jump on a force platform. Participants' body weight and a urine sample were also obtained before and after each match. The amount of liquid that the players drank during the match was also calculated by weighing their individual drinking bottles.Results and discussionSweat rate during the game was 1.14 ± 0.46 l/h in men and 1.02 ± 0.64 l/h in women. The players rehydrated at a rate of 1.10 ± 0.55 l/h and 1.01 ± 0.44 l/h in the male and female groups respectively. Thus, the dehydration attained during the game was only 0.37 ± 0.50% in men and 0.32 ± 0.83% in women. No differences were found in any of the parameters analyzed during the vertical jump (men: from 31.82 ± 5.29 to 32.90 ± 4.49 W/kg; p>0.05, women: from 26.36 ± 4.73 to 27.25 ± 4.44 W/kg; p>0.05). Post-exercise urine samples revealed proteinuria (60.9% of cases in men and 66.7% in women), leukocyturia (men = 43.5% and women = 50.0%) and erythrocyturia (men = 50.0% and women = 21.7%).ConclusionsDespite a moderate sweat rate, badminton players adequately hydrated during a game and thus the dehydration attained was low. The badminton match did not cause muscle fatigue but it significantly increased the prevalence of proteinuria, leukocyturia and erythrocyturia.

BACKGROUND: To investigate the cause/s of muscle fatigue experienced during a half-iron distance triathlon. METHODOLOGY/PRINCIPAL FINDINGS: We recruited 25 trained triathletes (36±7 yr; 75.1±9.8 kg) for the study. Before and just after the race, jump height and leg muscle power output were measured during a countermovement jump on a force platform to determine leg muscle fatigue. Body weight, handgrip maximal force and blood and urine samples were also obtained before and after the race. Blood myoglobin and creatine kinase concentrations were determined as markers of muscle damage. RESULTS: Jump height (from 30.3±5.0 to 23.4±6.4 cm; P0.05) but significantly correlated with myoglobin concentration (r = 0.65; P

El deporte de alto rendimiento exige un conocimiento exhaustivo de todos los aspectos implicados en el desarrollo deportivo. Por tanto, se antoja imprescindible profundizar, no solo en las características de los actores principales, entrenador y deportista, sino también en las de los sistemas de desarrollo deportivo en que se desenvuelven. Nos decantamos por el karate como objeto de estudio por ser esta una modalidad en la que nuestro país ocupa un lugar en la élite mundial. Se analizaron 15 clubes de elite de España, incluyendo a sus entrenadores (n = 17) y deportistas competidores senior y junior (n = 67). Se ha mostrado que uno de los puntos fuertes de los clubes deportivos que tienen grandes éxitos deportivos, es la contrapartida que reciben a su vez de estos deportistas de alto nivel. Al entrenar éstos en el club, están aumentando el nivel de entrenamiento y hacen que los demás deportistas se beneficien de este mayor nivel. Se crea lo que hemos denominado como Clima de excelencia, que se vive en el club y del que se hacen partícipes todos los integrantes del mismo, y que no solo sirve para aumentar el nivel deportivo, sino que además refuerza la motivación de los demás deportistas que perciben que pueden aspirar a esos niveles de rendimiento, al compartir el mismo sistema deportivo. Algo similar ocurre a nivel regional o local. Donde existe un mayor nivel, las competiciones (campeonatos regionales, locales, ligas de clubes) tienen mayor exigencia y esto propicia la mejora. En estos microsistemas deportivos, en virtud de lo citado por los deportistas, la clave de su buen funcionamiento radica en el factor humano, pues señalan las características del entrenador y del grupo como los puntos fuertes del club. Los entrenadores de estos clubes de elite se presentan como entrenadores expertos, con un amplio bagaje en el mundo del karate, con un conocimiento en primera persona de todas las facetas de este deporte, habiendo pasado por la etapa como deportista, competidor, entrenador y gestor. En cuanto a los deportistas, se estableció un perfil sociodemográfico y de su trayectoria deportiva, donde se aprecia que el entorno social próximo es un elemento clave en todas las fases de la carrera deportiva. Tanto el deportista como el entrenador coinciden en los factores que favorecen el éxito en la búsqueda de la excelencia en este deporte. Ambos indican, por este orden, aspectos del propio deportista, entrenador, club y/o grupo de entrenamiento, y el apoyo social de familia y amigos. Se ha puesto de manifiesto en los resultados obtenidos, que tanto el entorno social como deportivo en que se desarrolla el deportista son claves en la carrera deportiva de éste. El estudio pretende abordar el campo del rendimiento deportivo desde una perspectiva novedosa, como es la de los sistemas de desarrollo deportivo. Nos centramos en los microsistemas, pues en el ámbito de los sistemas deportivos, los estudios se han centrado casi exclusivamente en macrosistemas, estudiando los sistemas deportivos a nivel nacional o internacional, por lo que el ámbito nuclear, el de los clubes deportivos, no ha sido descrito. Así, pasamos de la esfera global a la particular y exploramos las características propias de estos elementos centrales del rendimiento.

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