Effect of caffeine intake on critical power model parameters determined on a cycle ergometer

The aim of this study was to evaluate the effect of caffeine intake on critical power model parameters determined on a cycle ergometer. Eight male subjects participated in this study. A double-blind protocol consisting of the intake of pure caffeine (6 mg/kg) or placebo (maltodextrin) 60 min before testing was used. Subjects were submitted to four constant-load tests on a cycle ergometer. These tests were conducted randomly in the caffeine and placebo groups [checar] at intensities of 80, 90, 100 and 110% maximum power at a rate of 70 rpm until exhaustion to determine the critical power. As a criterion for stopping the test was adopted any rate fall without recovery by more than five seconds. The critical power and anaerobic work capacity were obtained by nonlinear regression and fitting of the curve to a hyperbolic power-time model. The Shapiro-Wilk test and paired Student t-test were used for statistical analysis. No significant differences in critical power were observed between the caffeine and placebo groups (192.9 ± 31.3 vs 197.7 ± 29.4 W, respectively). The anaerobic work capacity was significantly higher in the caffeine group (20.1 ± 5.2 vs 16.3 ± 4.2 W, p<0.01). A high association (r²) was observed between the caffeine and placebo conditions (0.98 ± 0.02 and 0.99 ± 0.0, respectively). We conclude that caffeine intake did not improve critical power performance but increased anaerobic work capacity by influencing performance at loads of higher intensity and shorter duration.O objetivo do presente estudo foi verificar o efeito da ingestão de cafeína sobre os parâmetros do modelo de potência crítica determinado em cicloergômetro. Participaram do estudo oito sujeitos do sexo masculino. A ingestão de cafeína pura (6 mg.kg-1) ou placebo (maltodextrina) foi realizada através de protocolo duplo-cego, 60 minutos antes dos testes. Para determinação da potência crítica, os sujeitos foram submetidos a quatro testes de cargas constantes em cicloergômetro, realizados aleatoriamente, nos momentos cafeína e placebo, nas intensidades de 80, 90, 100 e 110% da potência máxima, a uma cadência de 70 rpm até a exaustão. A potência crítica e a capacidade de trabalho anaeróbio foram obtidas através de regressão não linear e ajuste de curva para o modelo hiperbólico potência-tempo. Para o tratamento estatístico, utilizaram-se-se o teste de Shapiro Wilk e o teste t de Student pareado. Não foram encontradas diferenças significativas na potência crítica nas condições cafeína e placebo (192,9 ± 31,3 vs 197,7 ± 29,4 W, respectivamente). A capacidade de trabalho anaeróbio foi significativamente maior na condição cafeína (20,1 ± 5,2 vs 16,3 ± 4,2 W, p< 0,01). Foi, ainda, obtido um alto valor de associação (r²) entre as condições cafeína e placebo (0,98± 0,02 e 0,99± 0,0). Através dos resultados obtidos, concluiu-se que a ingestão de cafeína não proporcionou melhorias no desempenho da potência crítica, entretanto, elevou os valores da capacidade de trabalho anaeróbio por influenciar o desempenho nas cargas de maior intensidade e menor duração.495

Efeito da ingestão de cafeína sobre o limiar de esforço percebido (LEP)

Caffeine is an ergogenic substance used to enhance sports performance. With central and peripheral effects, it may influences the perception of fatigue during exhaustive efforts with central and peripheral effects. The present study aimed to investigate the effects of caffeine ingestion on the perceived exertion threshold (PET). After completing maximum work load (Wmax) test on cycling ergometer, eight men executed four constant load tests (80, 90, 100 and 110% of Wmax) under caffeine (CAF) or placebo (PLA) ingestion for PET determination. The “t” Student paired test was used to compare PET under the analyzed conditions. There were no significant differences between CAF and PLA conditions for PET. However, during 100 and 110% constant load tests, CAF conditions presented longer exhausting time (P < 0,01) and the tests between 80% and 100% presented lower increasing ratings of perceived exertion (RPE) (P < 0,01). According to the results, it is possible to conclude that PET was not modified with CAF supplementation, even with higher performance during the most intensive tests and attenuation of the increasing rate of RPE in 80% and 100% loads.A cafeína é substância ergogênica utilizada para aprimorar o rendimento esportivo. Com efeitos centrais e periféricos, pode interferir na percepção de fadiga durante esforços exaustivos. O presente estudo objetivou investigar o efeito da ingestão de cafeína sobre o limiar de esforço percebido (LEP). Após estabelecer a carga máxima de trabalho (Wmax) por teste incremental em cicloergômetro, oito homens realizaram quatro testes de carga constante (80, 90, 100 e 110% da Wmax) sob ingestão de cafeína (CAF) ou placebo (PLA) para determinação do LEP. Para contrastar os dados, utilizou-se o teste “t” de Student pareado. Não foram encontradas diferenças significativas entre os valores de LEP em nenhuma das condições, porém, na condição CAF os testes constantes de 100 e 110% apresentaram maior tempo de exaustão (P < 0,01), e os testes de 80 e 100% apresentaram menor taxa de aumento da percepção subjetiva de esforço (PSE) (P < 0,01). De acordo com os resultados, é possível concluir que o LEP não foi modificado com a suplementação de CAF, mesmo com desempenho superior durante os testes mais intensos e atenuação da taxa de aumento da PSE nas cargas 80 e 100%

The influence of the different information about the time of the exercise on the eletromyographic and the oxygen uptake at cyclists

Orientador: Antonio Carlos de MoraesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação FisicaResumo: O propósito do presente estudo foi verificar o efeito de diferentes informações sobre o tempo de teste a se realizar sobre variáveis fisiológicas específicas. Participaram da amostra 10 ciclistas homens (1,76 ± 0,04 metros, 78,48 ± 10,40 kg e 32,5 ± 6,02 anos), submetidos a teste incremental (início de 100W e acréscimo de 20W.min-1) para determinação da potencia pico (PP) (369,84 ± 37,77 W) e consumo máximo de oxigênio (VO2máx) (51,90 ± 10,37 ml/kg/min). Além disso, realizaram outros quatro protocolos intermitentes (4 min a 50% da PP intervalados por 1 min a 100% da PP), em dias distintos, separados por no mínimo 48 horas. O primeiro protocolo (P1) teve duração 40 minutos, durante o qual os voluntários foram informados sobre o tempo e distância percorridos apenas ao final do mesmo, ou seja, realizaram a tarefa sem nenhum conhecimento sobre ela. O segundo protocolo (P2) teve as mesmas características que P1, porém os voluntários já o conheciam e puderam acompanhar todas as informações coletadas durante o protocolo. No terceiro protocolo (P3) os voluntários foram informados que deveriam fazer o mesmo que em P1 e P2, todavia o protocolo foi encerrado ao vigésimo minuto sem nenhum aviso prévio. No quarto protocolo (P4) repetiram os 20 minutos de esforços intervalados, recebendo as informações corretas sobre a duração do teste e foram fortemente avisados que a duração do protocolo não seria alterada. Todos os testes foram realizados em ciclossimulador. A atividade eletromiográfica (EMG) dos músculos Reto Femoral (RF) e Vasto Lateral (VL) e o consumo de oxigênio (VO2) foram coletados durante todos os protocolos intermitentes. O nível de significância adotado foi de 5% (p=0,05). Os resultados demonstraram que a EMG (root mean square - RMS) do RF foi menor em P1 quando comparado: a P3 nos minutos 9, 10, 14, 15, 19 e 20; a P4 nos minutos 9, 14, 19 e 20; e em relação ao tempo. A freqüência mediana (FM) desse músculo não apresentou nenhuma diferença entre protocolos nem em relação ao tempo. O VL apresentou RMS maior em P1 comparado a P2 apenas no minuto 40. Em contrapartida a FM do VL em P2 foi maior que os outros protocolos (P1, P3 e P4) no minuto 5, no minuto 10 (P1 e P3), no minuto 15 (P3), e ainda mostrou aumento em relação ao tempo em P1 e P4. O VO2 foi significantemente maior em P4 quando comparado: a P2 nos minutos 5, 10 e 20; a P1 nos minutos 10 e 20. Adicionalmente P3 foi maior que P2 no minuto 20, e em todos os protocolos houve aumento significante em relação ao tempo. A partir dos resultados é possível concluir que as informações recebidas pelos voluntários interferem na EMG e no VO2 de forma diferente com a variação da carga.Abstract: The purpose of this study was to evaluate the effect of different information about the time of the test to be helded on specific physiological variables. Ten men cyclists (1.76 ± 0.04 m, 78.48 ± 10.40 kg and 32.5 ± 6.02 years old)was submitted to a incremental test (beginning of 100W and increased 20W.min - 1) to determine the peak power (PP) (369.84 ± 37.77 W) and maximum oxygen uptake (VO2max) (51.90 ± 10.37 ml / kg / min). Moreover, there were four other protocols intermittent (4 min at 50% of the PP intervals for 1 min to 100% of PP), on different days, separated by at least 48 hours. The first protocol (P1) lasted 40 minutes, during which the volunteers were informed about the time and distance traveled only at the end of it, ie, performed the task without any knowledge about it. The second protocol (P2) had the same characteristics as P1, but the volunteers had the knowledge and could check all the information collected during the protocol. In the third protocol (P3) the volunteers were informed that should do the same in P1 and P2, but the protocol was closed for twenty minutes without any notice. In the fourth protocol (P4) the repeated efforts of 20 minutes intervals, getting the correct information on the duration of the test and were strongly advised that the duration of the protocol would not be changed. All tests were performed in cyclosimulator. The electromyographic activity (EMG) of the muscle Rectus Femoral (RF) and Vastus Lateralis (VL) and oxygen consumption (VO2) were collected during all protocols intermittent. The significance level was 5% (p = 0.05). The results showed that the EMG (root mean square - RMS) of RF was lower in Q1 compared: the P3 in the minutes 9, 10, 14, 15, 19 and 20, and P4 in 9 minutes, 14, 19 and 20; and increase over the time. The median frequency (MF) of the muscle showed no differences between any protocols even in relation with the time. The VL had higher RMS in P1 compared to P2 in just 40 minutes. In contrast to the VL in FM P2 was higher than the other protocols (P1, P3 and P4) at the minute 5, minute 10 (P1 and P3), at the minute 15 (P3), and showed an increase in the time in P1 and P4. The VO2 was significantly higher when compared to P4: P2 in the minutes 5, 10 and 20, the P1 in minutes 10 and 20. Additionally P2 to P3 was higher at the minute 20, and in all protocols there was a significant increased in relation to time. From the results we conclude that the information received by volunteers has an influence at the EMG and VO2 in different ways with the change in the load.MestradoCiencia do DesportoMestre em Educação Físic

Reflexões introdutorias sobre a administração esportiva na formação do profissional de educação fisica

O presente trabalho se dedica a realizar algumas reflexões acerca da administração esportiva na formação do profissional de Educação Física, levando em consideração a falta de estudos aprofundados e bibliografia nessa área, com o objetivo de explorar introdutoriamente os possíveis conhecimentos necessários à formação profissional da Educação Física e a habilitação necessária para atuar nesse campo. Para tanto, uma breve retomada histórica foi Sistematizada visando entender a relação da Educação Física e o Esporte nas diferentes fase. Outra discussão presente foi o estudo de alguns documentos que ampliam as possibilidades de formação do profissional de Educação Física para a gestão esportiva, como a resolução 03/87 que possibilitou a criação dos cursos de bacharelado e a fundação da Faculdade de Educação física da Unicamp pioneira neste assunto. A partir daí percorrer a trajetória destas até a atualidade. Descrevendo seus objetivos, suas transformações e suas perspectivas. Em um segundo momento buscou-se entender o perfil profissional procurado e encontrado no mercado atual, apontando características relevantes do profissional, através de estudos teóricos e alguns aplicados na prática. Por fim, discutiu-se alguns aspectos em comum entre a concepção teórica e o campo de trabalho na formação profissional dessa área, sem qualquer intenção de propor novos parâmetros curriculares.The aim of the present study was to reflect about sports administration in the graduation of the professional of Physical Education, considering the lack of deepened studies and bibliography in this area, with the purpose to explore introducing the possible knowledge necessary to the professional graduation and the qualification necessary to act in this area. For this, a brief historical retaken was systemized aiming at to understand the relation of the Physical Education and the Sport in different phases. Another present quarrel was the study of some documents which extends the possibilities of formation of the Physical Education professional for the sports management, like the 03/87 resolution that made possible the creation of bachelor courses and the foundation of the College of Physical Education of the pioneering Unicamp in this subject. From this point, covering the trajectory until the present time, describing its objectives, its transformations and its perspectives. In a second moment, it was attempted to understand the professional profile searched and found in the current market, pointing its notable characteristic, through theoretical studies and some applied experiences. At last, it discussed about some aspects between the theoretical conception and the business area in the professional formation, without any intention to consider new curricular parameters

<b>The influence of different distances on determination of critical velocity in swimmers </b>

The purpose of this study was to determine the influence of different distance combinations on critical velocity (CV) and anaerobic work capacity (AWC). Nineteen swimmers experienced in this training modality participated in the study. CV was calculated by the angular coefficient of the linear regression line between distance and time obtained for each repetition. Five distances (50, 100, 200, 400 and 800 m) performed at an interval of 24 hours were used for the determination of CV, followed by the following four combinations of distances: CV1 (50, 100 and 200 m), CV2 (100, 200 and 400 m), CV3 (200, 400 and 800 m), and CV4 (50, 100, 200, 400 and 800 m). The Shapiro-Wilk test was used to determine the normality of the data. One-way ANOVA was used for comparisons between CV and the different combinations of shots (p < 0.05). The combination of smaller distances (CV1) resulted in an increase of CV (1.47 ± 0.13) and a decrease of AWC (11.91 ± 2.61). The use of shots of medium and long distance resulted in a lower CV (1.38 ± 0.10, 1.34 ± 0.09 and 1.36 ± 0.09 for CV2, CV3 and CV4, respectively) and higher AWC (19.84 ± 6.74, 27.44 ± 6.91 and 18.43 ± 5.21) when compared to short shots. The results suggest that shot distance influences CV and AWC, overestimating or underestimating the speed corresponding to maximum lactate steady state

<b>Can neuromuscular fatigue threshold bedetermined by short and non-exhaustive bouts?</b>. DOI: http://dx.doi.org/10.5007/1980-0037.2012v14n3p254

The present study determined the neuromuscular fatigue threshold (NFT) using four different time-periods of analysis of the electromyographic signal and compared these estimations with critical power (CP). Fifteen healthy young men (73.6 ± 5.1 kg, 177.8 ± 7.0 cm, 23.4 ± 5.2 years) performed 3-4 different severe constant workload trials until exhaustion on a cycle ergometer with simultaneous SEMG signals acquisition. The obtained data permitted NFT estimation with four different periods of analysis as follows: initial 30s (T30), 1min (T1), 2min (T2) and total time (TT), as well as CP. T30 and T1 were significantly higher than TT and CP and, T2 and TT did not differ between each other, and both were significantly higher than CP. In addition, TT was significantly correlated to CP (0.72; P < 0.05) and to T2 (0.58; P < 0.05). We conclude that NFT overestimates CP, independent of the time-period analysis used for its determination

Can neuromuscular fatigue threshold bedetermined by short and non-exhaustive bouts?

The present study determined the neuromuscular fatigue threshold (NFT) using four different time-periods of analysis of the electromyographic signal and compared these estimations with critical power (CP). Fifteen healthy young men (73.6 ± 5.1 kg, 177.8 ± 7.0 cm, 23.4 ± 5.2 years) performed 3-4 different severe constant workload trials until exhaustion on a cycle ergometer with simultaneous SEMG signals acquisition. The obtained data permitted NFT estimation with four different periods of analysis as follows: initial 30s (T30), 1min (T1), 2min (T2) and total time (TT), as well as CP. T30 and T1 were significantly higher than TT and CP and, T2 and TT did not differ between each other, and both were significantly higher than CP. In addition, TT was significantly correlated to CP (0.72; P < 0.05) and to T2 (0.58; P < 0.05). We conclude that NFT overestimates CP, independent of the time-period analysis used for its determination

Effect of caffeine intake on critical power model parameters determined on a cycle ergometer

The aim of this study was to evaluate the effect of caffeine intake on critical power model parameters determined on a cycle ergometer. Eight male subjects participated in this study. A double-blind protocol consisting of the intake of pure caffeine (6 mg/kg) or placebo (maltodextrin) 60 min before testing was used. Subjects were submitted to four constant-load tests on a cycle ergometer. These tests were conducted randomly in the caffeine and placebo groups [checar] at intensities of 80, 90, 100 and 110% maximum power at a rate of 70 rpm until exhaustion to determine the critical power. As a criterion for stopping the test was adopted any rate fall without recovery by more than five seconds. The critical power and anaerobic work capacity were obtained by nonlinear regression and fitting of the curve to a hyperbolic power-time model. The Shapiro-Wilk test and paired Student t-test were used for statistical analysis. No significant differences in critical power were observed between the caffeine and placebo groups (192.9 ± 31.3 vs 197.7 ± 29.4 W, respectively). The anaerobic work capacity was significantly higher in the caffeine group (20.1 ± 5.2 vs 16.3 ± 4.2 W, p< 0.01). A high association (r2) was observed between the caffeine and placebo conditions (0.98 ± 0.02 and 0.99 ± 0.0, respectively). We conclude that caffeine intake did not improve critical power performance but increased anaerobic work capacity by influencing performance at loads of higher intensity and shorter duration