The effects of different doses of caffeine on performance, rating of perceived exertion and pain perception in teenagers female karate athletes

ABSTRACT The present study set to examine the effects of different doses of caffeine on performance, rating of perceived exertion (RPE), and pain perception in female teenager athletes of karate. Ten female karate athletes (16.8±1.23 years; height 1.59±0.28 m; body-mass 57.73±8.33 kg; BMI 22.71±3.05 kg/m2) participated in the study. A double-blind, randomized, and crossover counterbalanced design was used. In three sessions (with an interval of seven days'), ten female karate athletes ingested low dose (2 mg/kg), moderate dose (5 mg/kg) caffeine, and placebo. Sixty minutes after consumption, they performed the tests as below: one repetition maximum and 60% of one repetition maximum in the leg press, explosive power test, and anaerobic RAST test. After the tests, the participants' RPE (6-20 scale) and pain perception (0-10 scale) were recorded using various categorical scales. The results showed that caffeine ingestion at moderate dose significantly reduced RPE and pain perception values compared with the placebo during muscular endurance test (P=0.0001 and P=0.039, respectively). The findings suggest that caffeine dose of 5 mg/kg body mass appears to improve RPE and pain perception in female teenager athletes of karate. The dose of 2 mg/kg body mass does not confer any additional improvement in performance.

Fase do treinamento esportivo não afeta a variabilidade da frequência cardíaca em atletas de jiu-jitsu / Phase of sports training does affect the heart rate variability in a athletes of jiu-jitsu

O objetivo desse estudo foi avaliar a modulação autonômicacardíaca de atletas de jiu-jitsu, comparando-os com sedentáriose avaliando as alterações dessa modulação ao longo dasdiferentes fases de treinamento. Foram avaliados sete atletas esete indivíduos sedentários do sexo masculino (23 ± 4 e 24 ± 3anos, respectivamente). A frequência cardíaca (FC) e o sinalrespiratório foram coletados por 10 minutos na posição deitadaem três fases do treinamento dos atletas (preparatória, competitivae transitória) e num único momento nos sedentários.A modulação autonômica cardíaca foi avaliada pela análiseespectral da variabilidade da FC (VFC) utilizando-se o modeloautorregressivo. A comparação entre os grupos foi feitapelos testes t não pareado ou Mann-Whitney. A comparaçãoentre as fases de treinamento no grupo de atletas foi realizadapela ANOVA de um fator para amostras repetidas (p < 0,05).Os grupos apresentaram características físicas e funcionaissemelhantes, mas a força máxima foi significantemente maiornos atletas. Todos os índices de VFC foram semelhantes entreos atletas e os sedentários. Além disso, esses índices não sealteraram significantemente entre as fases preparatória, competitivae transitória do treinamento dos atletas. Em conclusão, osatletas de jiu-jitsu apresentam modulação autonômica cardíacasemelhante à de sedentários, e essa modulação não se alteranas diferentes fases de periodização do treinamento.

The aim of this study was to evaluate cardiac autonomic modulationin jiu-jitsu athletes, comparing with sedentary individuals,and evaluating changes that may happen throughout the differentphases of training. Seven athletes and seven sedentary males (23± 4 e 24 ± 3 years, respectively) were evaluated. Heart rate (HR)and respiratory signal were collected for 10 min in the supineposition in the three phases of training (preparatory, competitiveand transient) in the athletes and at one moment in the sedentarysubjects. Cardiac autonomic modulation was evaluated by thespectral analysis of HR variability (HRV) using the autoregressivemodel. Comparisons between groups were performed byunpaired t-test or Mann-Whitney test. Comparisons among thetraining phases were performed by one-way ANOVA for repeatedmeasures (p < 0.05). Athletes and sedentary subjects presentedsimilar physical and cardiovascular characteristics, althoughmaximal strength was significantly higher in the athletes. All ofthe HRV indexes were similar between athletes and sedentarysubjects. In addition, HRV indexes did not change among thepreparatory, competitive and transition phases of training. Inconclusion, jiu-jitsu athletes have cardiac autonomic modulationsimilar to sedentary subjects and this modulation is not changedthroughout the different periodization phases of training.

Efeitos da prática de tai chi chuan no equilíbrio de idosas independentes / Effects of tai chi chuan practice on balance in physically independent older women

Exercícios físicos têm sido prescritos como prevenção de quedas na terceira idade. Nesse ensaio clínico controlado, a prática de tai chi chuan conseguiu melhorar o equilíbrio de mulheres idosas fisicamente independentes, em avaliações de mobilidade funcional (avaliação de equilíbrio e marcha de Tinetti).Em relação a avaliações pela posturografia dinâmica computadorizada sobre organização sensorial e controle motor, não houve alterações. O grupo controle, submetido somente a programa educacional, evoluiu com piora do desempenho na mobilidade funcional, demonstrado provavelmente como conseqüência da falta de atividade física programada / Physical exercises have been prescribed for elderly people in order to delay the incidence of falls. In this controlled clinical trial, tai chi chuan training group improved balance scores assessed by functional mobility test (Performance Oriented Mobility Assessment) in independent elderly women. Sensory organization and motor control test results did not change after intervention (computerized dynamic posturography protocols). Otherwise, subjects in the control group that had attended educational meetings, decreased their mobility performance, probably due to lack of engagement in a fitness program...