RESUMOA suplementação de creatina vem sendo utilizada amplamente na tentativa de aumentar força e massa magra em sujeitos saudáveis e atletas. Além disso, diversos estudos têm sido conduzidos no intuito de desvendar os mecanismos responsáveis pelas eventuais adaptações a esse suplemento. Diante disso, essa revisão teve como objetivos: 1) discutir os principais estudos que investigaram os efeitos da suplementação de creatina na força e hipertrofia; e 2) reunir as evidências acerca dos possíveis mecanismos responsáveis pelo aumento de força e massa magra como consequência desse suplemento, enfatizando os mais recentes achados e as perspectivas sobre o tema. De fato, existem fortes evidências demonstrando que a suplementação de creatina é capaz de promover aumentos de força e hipertrofia. Os efeitos desse suplemento sobre a retenção hídrica, o balanço proteico, a expressão de genes/proteínas associados à hipertrofia e ativação de células satélites, podem explicar as adaptações musculoesqueléticas observadas. Diante desses achados, os potenciais efeitos terapêuticos desse suplemento emergem como um futuro e promissor campo de estudo.Palavras-chave: efeitos ergogênicos, mecanismos, suplementos nutricionais. ABSTRACTCreatine supplementation has been widely used to increase both muscle strength and lean mass in healthy individuals and athletes. Furthermore, several studies have investigated the mechanisms responsible for such adaptations. Thus, this review aimed at 1) examining the major studies investigating the effects of creatine supplementation on strength and hypertrophy, and 2) exploring the mechanisms underlying these responses, stressing the most recent findings and perspectives regarding creatine supplementation. There is strong evidence demonstrating that creatine supplementation is able to enhance strength and hypertrophy. The effects of creatine on water retention, protein balance, genes/proteins related to hypertrophy, and satellite cells activation may explain the creatine-mediated muscle skeletal adaptations. In light of these findings, the potential therapeutic effects of creatine supplementation might be considered as a promising clinical and research field.Keywords: ergogenic effects, mechanisms, nutritional supplements. INTRODUÇÃOA creatina (ácido α-metil guanidino acético) é uma amina de ocorrência natural sintetizada endogenamente pelo fígado, rins e pâncreas, a partir dos aminoácidos glicina e arginina (1) . Pode também ser obtida via alimentação, especialmente pelo consumo de carne vermelha e peixes. A produção endógena (1g/dia) somada à obtida na dieta (1g/dia para uma dieta onívora) se iguala à taxa de degradação espontânea da creatina e fosfocreatina sob a forma de creatinina, por reação não enzimática (1) . A creatina é encontrada no corpo humano nas formas livre (60 a 70%) e fosforilada (30 a 40%). Cerca de 95% é armazenada no músculo esquelético, sendo que o restante situa-se no coração, músculos lisos, cérebro e testículos (2) . Desde que foi demonstrado que a suplementação de creatina ...
Running economy (RE) is defined as the energy cost to maintain a submaximal running velocity and seems to be affected by individual's neuromuscular characteristics, such as stiffness level. Both resistance training (RT) and whole-body vibration training added to RT (WBV + RT) have been shown to influence those characteristics. Thus, it is conceivable that RT and WBV + RT could also affect RE. The objective of this study was to investigate if a 6-week training period of RT and WBV + RT influences RE and vertical stiffness (VS). Fifteen recreational runners were divided into RT or WBV + RT groups. Running economy, VS, and lower-limb maximum dynamic strength (1 repetition maximum [1RM] half-squat) were assessed before and after the 6-week training period. There was a main time effect for 1RM, but no other statistically significant difference was observed. Neither conventional RT nor RT performed on a WBV platform improved VS and RE in recreational long distance runners. It is possible that movement velocity was rather low, and utilization of stretch-shortening cycle might have been compromised, impairing any expected improvement in RE.
The purpose of this study was to investigate the main bioenergetics and neuromuscular determinants of the time to exhaustion (T(lim)) at the velocity corresponding to maximal oxygen uptake in recreational long-distance runners. Twenty runners performed the following tests on 5 different days: (a) maximal incremental treadmill test, (b) 2 submaximal tests to determine running economy and vertical stiffness, (c) exhaustive test to measured the T(lim), (d) maximum dynamic strength test, and (e) muscle power production test. Aerobic and anaerobic energy contributions during the T(lim) test were also estimated. The stepwise multiple regression method selected 3 independent variables to explain T(lim) variance. Total energy production explained 84.1% of the shared variance (p = 0.001), whereas peak oxygen uptake (V(O2)peak) measured during T(lim)and lower limb muscle power ability accounted for the additional 10% of the shared variance (p = 0.014). These data suggest that the total energy production, V(O2)peak, and lower limb muscle power ability are the main physiological and neuromuscular determinants of T(lim)in recreational long-distance runners.
RESUMO O objectivo do estudo se pautou em determinar as características de parâmetros das forças de reacção do solo (FRS) em movimentos típicos do basquetebol executados por jogadores profissionais. Também se objectivou determinar correlações entre o desempenho nos saltos e sua carga mecânica durante as aterrissagens. Oito atletas realizaram cinco tentativas em seis movimentos: arremesso em suspensão (jump), salto com contramovimento (jump & reach), bandeja, rebote e corrida com bola rápida (v=6m/s) e lenta (v=4m/s). Os parâmetros dinâmicos da FRS foram colectados através de uma plataforma de força (KISTLER AG 9287). Os resultados do primeiro pico da força vertical na aterrissagem, do tempo para o para o pico e do impulso foram: no jump 4,
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