Effect of acute administration of Clenbuterol on athletic performance in horses

The aim of the study was to determine the effect of clenbuterol on the anaerobic-threshold of horses on a tread-mill with increasing physical stress, measuring heart rate (HR) and blood levels of lactate, glucose, and insulin. Twelve Arabian horses. were submitted to two physical tests separated by a 10-day interval. Clenbuterol (CL) at 0.8 mu g/kg or saline (control-C) was administered intravenously 30 minutes, before the test. The treadmill exercise test consisted of an initial warmup followed by a gradually increasing effort. There was no statistical difference in either V-2 or V-4 (velocity at which plasma lactate concentration reached 4 and 2 mmol/L, respectively) between the two-experimental groups. For the CL group, V-200, V-180, V-160, and V-140 (velocity at which the rate heart is 140, 160, 180, and 200 beats/minute, respectively) decreased significantly. At rest as well as times 4, 6, and 10 minutes, insulin levels were higher in the group that recieved clenbuterol (P < .05). Contrary to what was expected, apparently, there was no improvement in aerobic metabolism in animals when given a therapeutic dose of the bronchodilator. The elevated heart rate observed could have been attributable to the stimulation of cardiac beta(1) adrenoceptors and the increased insulin levels to the stimulation of pancreatic beta(2) receptors.

Limiar anaeróbio e velocidade crítica determinada com diferentes distâncias em nadadores de 10 a 15 anos: relações com a performance e a resposta do lactato sanguíneo em testes de endurance

O objetivo deste estudo foi comparar a velocidade crítica (VC) determinada através de diferentes distâncias com o limiar anaeróbio (LAn) e as velocidades máximas mantidas em testes de 20 (V20) e 30 (V30) minutos na natação, verificando se a idade cronológica em jovens nadadores interfere nessas relações. Participaram do estudo 31 nadadores (17 meninas e 14 meninos) divididos segundo a idade cronológica em dois grupos: 10 a 12 anos e 13 a 15 anos. O LAn foi determinado como sendo a velocidade correspondente a 4mM de lactato sanguíneo. A VC1 (25/50/100m), VC2 (100/200/400m) e a VC3 (50/100/200m) foram calculadas através do coeficiente angular da reta de regressão linear entre as distâncias e seus respectivos tempos. As V20 e V30 foram determinadas através de três a seis repetições, com coletas de sangue no 10º minuto e ao final do tiro. Para o grupo de 10 a 12 anos, a VC1 (m/s) (0,98 ± 0,17) e o LAn (0,97 ± 0,12) não foram diferentes entre si, sendo maiores do que a VC2 (0,92 ± 0,16), VC3 (0,89 ± 0,18), V20 (0,92 ± 0,11) e V30 (0,90 ± 0,11). Para o grupo de 13 a 15 anos, a VC1 (m/s)(1,11 ± 0,11) foi maior do que o LAn (1,02 ± 0,07), V20 (0,99 ± 0,09), V30 (0,97 ± 0,09), VC2 (0,98 ± 0,11) e VC3 (1,00 ± 0,11). Pode-se concluir que a distância utilizada na determinação da VC interfere no valor obtido, independente da idade cronológica. A VC determinada com distâncias entre 50 e 400m pode ser utilizada na avaliação da capacidade aeróbia de crianças e adolescentes, substituindo os testes contínuos máximos com durações próximas a 20 ou 30 minutos.

Utilização do intercepto-y na avaliação da aptidão anaeróbia e predição da performance de nadadores treinados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Feed restriction and a diet's caloric value: The influence on the aerobic and anaerobic capacity of rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Validity of the running anaerobic sprint test for assessing anaerobic power and predicting short-distance performances

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

RESPONSES of HEMATOLOGICAL PARAMETERS and AEROBIC PERFORMANCE of ELITE MEN and WOMEN SWIMMERS DURING A 14-WEEK TRAINING PROGRAM

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Índices fisiológicos associados com a performance aeróbia em corredores de endurance: efeitos da duração da prova

O objetivo deste estudo foi analisar a validade do consumo máximo de oxigênio (VO2max), da velocidade correspondente ao VO2max (vVO2max), do tempo de exaustão na vVO2max (Tlim), da economia de corrida (EC) e do limiar anaeróbio (LAn) para a predição da performance de atletas de endurance. Quatorze corredores de endurance (33,4 ± 4,4 anos; 62,7 ± 4,3kg; 166,1 ± 5,0cm; VO2max = 60,4 ± 5,9ml.kg-1.min-1) realizaram os seguintes testes: a) competição simulada nas distâncias de 1.500 e 5.000m. e; b) testes de laboratório para a determinação do VO2max, vVO2max, EC, LAn e Tlim na intensidades de 100% vVO2max. As velocidades (km/h) da vVO2max (18,7 ± 0,8), LAn (17,3 ± 1,1) v1.500m (19,9 ± 0,8) e v5.000m (17,9 ± 0,9) foram significantemente diferentes. A regressão múltipla stepwise revelou que o LAn foi o único preditor da performance da v5.000m, explicando 50% da variação desta performance. Para a v1.500m, o Tlim e a vVO2max explicaram 88% da variação da performance. Com base em nossos resultados, pode-se concluir que a validade dos índices fisiológicos (VO2max, vVO2max, Tlim, EC e LAn), para a predição da performance aeróbia de atletas de endurance, é dependente da distância da prova (1.500 x 5.000m) analisada.

Validade do teste de 30 minutos (T-30) na determinação da capacidade aeróbia, parâmetros de braçada e performance aeróbia de nadadores treinados

O objetivo do presente estudo foi verificar a utilização da velocidade de 30 minutos (VT-30), freqüência de braçada (fB), comprimento de braçada (CB) e índice de braçada (IB), obtidos no teste T-30, como métodos não-invasivos para determinação da performance aeróbia e técnica de nadadores treinados. Catorze nadadores submeteram-se a três esforços de 400m (85, 90 e 100% do esforço máximo) para determinação da velocidade de limiar anaeróbio (VLan) correspondente à concentração fixa de 3,5mM de lactato e um esforço máximo de 30 minutos (VT-30). fB, CB e IB foram calculados nos 10m centrais da piscina (nado limpo) para o teste T-30 (fBT-30, CBT-30 e IBT-30) e progressivo. Através da relação entre VLan e parâmetros de braçada no teste progressivo, determinaram-se freqüência de braçada de limiar (fBLan), comprimento de braçada de limiar (CBLan) e índice de braçada de limiar (IBLan). O tempo para realizar 400m em máximo esforço foi considerado como parâmetro de performance (P400). Não foi encontrada diferença significativa entre VLan (1,29 ± 0,07m.s-1) e VT-30 (1,29 ± 0,08m.s-1), que ainda apresentaram alta correlação (r = 0,90). Os valores de fBLan (33,6 ± 4,14 ciclos/min) e fBT-30 (34,9 ± 3,53 ciclos/min) e de CBLan (2,09 ± 0,20m/ciclo) e CBT-30 (2,09 ± 0,20m/ciclo) também não foram significativamente diferentes. Correlações significativas (p < 0,05) também foram encontradas entre VT-30 e P400 (r = 0,95); fBLan e fBT-30 (r = 0,73); CBLan e CBT-30 (r = 0,89) e IBLan e IBT-30 (r = 0,94). Conclui-se que a VT30 se mostrou confiável para o monitoramento do treinamento, predição da performance e determinação de parâmetros relacionados à técnica de nadadores.

Variáveis fisiológicas e neuromusculares associadas com a performance aeróbia em corredores de endurance: efeitos da distância da prova

O objetivo deste estudo foi analisar a validade do consumo máximo de oxigênio (VO2max), velocidade associada ao VO2max (vVO2max), tempo de exaustão na vVO2max (Tlim), limiar anaeróbio (LAn), economia de corrida (EC) e força explosiva (FE) para predizer a performance aeróbia de corredores de endurance nas distâncias de 1.500m, 5.000m e 10.000m. Participaram deste estudo 11 corredores de endurance moderadamente treinados (28,36 ± 6,47 anos) que realizaram os seguintes testes: provas simuladas em uma pista de 400m em diferentes dias, nas distâncias de 10.000m, 5.000m e 1.500m; teste incremental máximo para determinar os índices VO2max, vVO2max, e LAn; um teste submáximo de carga constante para determinar a EC, seguido por um teste máximo também de carga constante a 100% da vVO2max para determinar o Tlim; e um teste de salto vertical para determinar a FE. de acordo com a análise de regressão múltipla, a vVO2max utilizada de forma isolada explicou 57% da variação de performance na prova de 1.500m. No entanto, quando o Tlim, a FE e a vVO2max foram analisados em conjunto, a explicação para a performance nessa prova foi de 88%. Nos 5.000m, o Tlim, a vVO2max e o LAn responderam por 88% da variação de performance (p < 0,05). Diferentemente, na prova de 10.000m, o LAn foi a única variável que apresentou capacidade de predição de performance. em conclusão, a predição da performance aeróbia de corredores moderadamente treinados por meio de variáveis fisiológicas e neuromusculares é dependente da distância da prova (1.500m, 5.000m e 10.000m)

Performance of UASB reactors in two stages under different HRT and OLR treating residual waters of swine farming

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of caffeine on time to exhaustion in exercise performed below and above the anaerobic threshold

Controversy still exists concerning the potential ergogenic benefit of caffeine (CAF) for exercise performance. The purpose of this study was to compare the effects of CAF ingestion on endurance performance during exercise on a bicycle ergometer at two different intensities, i.e., approximately 10% below and 10% above the anaerobic threshold (AT). Eight untrained males, non-regular consumers of CAF, participated in this study. AT, defined as the intensity (watts) corresponding to a lactate concentration of 4 mM, was determined during an incremental exercise test from rest to exhaustion on an electrically braked cycle ergometer. on the basis of these measurements, the subjects were asked to cycle until exhaustion at two different intensities, i.e., approximately 10% below and 10% above AT. Each intensity was performed twice in a double-blind randomized order by ingesting either CAF (5 mg/kg) or a placebo (PLA) 60 min prior to the test. Venous blood was analyzed for free fatty acid, glucose, and lactate, before, during, and immediately after exercise. Rating of perceived exertion and time to exhaustion were also measured during each trial. There were no differences in free fatty acids or lactate levels between CAF and PLA during and immediately after exercise for either intensity. Immediately after exercise glucose increased in the CAF trial at both intensities. Rating of perceived exertion was significantly lower (CAF = 14.1 ± 2.5 vs PLA = 16.6 ± 2.4) and time to exhaustion was significantly higher (CAF = 46.54 ± 8.05 min vs PLA = 32.42 ± 14.81 min) during exercise below AT with CAF. However, there was no effect of CAF treatment on rating of perceived exertion (CAF = 18.0 ± 2.7 vs PLA = 17.6 ± 2.3) and time to exhaustion (CAF = 18.45 ± 7.28 min vs PLA = 19.17 ± 4.37 min) during exercise above AT. We conclude that in untrained subjects caffeine can improve endurance performance during prolonged exercise performed below AT and that the decrease of perceived exertion can be involved in this process

Validity of the critical speed to determine blood lactate response and aerobic performance in swimmers aged 10-15 years

Introduction - the aim of this study was to analyze the validity of the critical speed (CS) to determine the speed corresponding to 4 mmol 1(-1) of blood lactate (S4) and the speed in a 30 min test (S30min) of swimmers aged 10-15 years.Synthesis of facts - CS, S4 and S30min were determined in 12 swimmers (eight boys and four girls) divided into two groups: 10-12 years and 13-15 years.Conclusion - CS was a good predictor of aerobic performance (S30min) independent of the chronological age, providing practical information about the aerobic performance state of young swimmers. (C) 2002, Editions scientifiques et medicates, Elsevier SAS. All rights reserved.

Assessment of anaerobic power of swimmers: the correlation of laboratory tests on an arm ergometer with field tests in a swimming fool

The aim of this study was to verify the correlation between the Wingate arm crank test outputs (peak power, mean power, and fatigue index), obtained on a specific ergometer, and the performance in crawl stroke swim sprints of 14, 25, 50, and 400 m. The experiment was conducted with 9 healthy male volunteers (18.1 +/- 2.2 years of age; 172 +/- 0.04 cm; 67.7 +/- 5.92 kg and 15.7 +/- 4.57% body fat). on determined days, all individuals were submitted to the Wingate arm crank test and crawl freestyle sprints of 14, 25, 50, and 400 m as they were timed with a stopwatch. The peak power, the mean power, and the fatigue index, which were obtained during the Wingate arm crank test, were not significantly correlated with the maximum swim velocities during the crawl free-style tests of 14 (r = 0.40; r = 0.64; r = 0.11), 25 (r = 0.28; r = 0.39; r = -0.27), 50 (r = 0.03; r = 0.09; r = -0.31), and 400 (r = -0.52; r = -0.37; r = -0.65) m respectively. Thus, it is possible to conclude that the Wingate arm crank test is not suitable to assess the anaerobic power of swimmers under the described experimental conditions.

Assessment of Anaerobic Power of Swimmers: The Correlation of Laboratory Tests on an Arm Ergometer with Field Tests in a Swimming Pool

The aim of this study was to verify the correlation between the Wingate arm crank test outputs (peak power, mean power, and fatigue index), obtained on a specific ergometer, and the performance in crawl stroke swim sprints of 14, 25, 50, and 400 m. The experiment was conducted with 9 healthy male volunteers (18.1 ± 2.2 years of age; 172 ± 0.04 cm; 67.7 ± 5.92 kg and 15.7 ± 4.57% body fat). On determined days, all individuals were submitted to the Wingate arm crank test and crawl freestyle sprints of 14, 25, 50, and 400 m as they were timed with a stopwatch. The peak power, the mean power, and the fatigue index, which were obtained during the Wingate arm crank test, were not significantly correlated with the maximum swim velocities during the crawl freestyle tests of 14 (r = 0.40; r = 0.64; r = 0.11), 25 (r = 0.28; r = 0.39; r = -0.17), 50 (r = 0.03; r = 0.09; r = -0.31), and 400 (r = -0.52; r = -0.37; r = -0.65) m, respectively. Thus, it is possible to conclude that the Wingate arm crank test is not suitable to assess the anaerobic power of swimmers under the described experimental conditions.

Responses of blood lactate concentration in aerobic and anaerobic training protocols at different swimming exercise intensities in rats

A swimming periodized experimental training model in rats in which different training protocols (TP) were classified in aerobic (A) and anaerobic (AN) intensity levels. The purpose of the present study was to verify if the classification of the TP used in the periodized training experimental model presented the blood lactate concentration [La] response adequate to the aerobic and anaerobic intensities levels. Twenty three male Wistar rats were divided into three groups. Two groups of swimming training (continuous, CT, n = 7, and periodized training, PET, n = 7) rats were evaluated during 5 weeks in eight different TP (TP-1 to TP-8) through the analysis of the [La] response. The third group was the sedentary control (SC, n = 9). The TP were classified in five intensity levels, three aerobic (A-1, A-2, A-3) and two anaerobic (AN-1, AN-2). Analysis of variance (ANOVA one-way, P<0.05) indicated significant differences in the [La] among the TP and among the five intensity levels. All TP of the A-2 and A-3 intensity levels differed from the A-1 and AN-1. The A-1 and AN-1 also differed among them. These findings demonstrate that the TP were classified properly at different levels of aerobic and anaerobic intensities, as based on the [La] response in a way similar to that of high performance swimming with humans. The results offer new perspectives for the study of exercise training in swimming rats at different levels intensity for performance or for health.