Comparison among the critical velocity determined by three conventional models and anaerobic threshold in running

The aim of this study was verify the use of critical velocity (CV) determined by three conventional models for prediction of the anaerobic threshold (AnT) in running. Thirteen Brazilian armed forces soldiers (age 24.6±6.6 years; body mass 74.4±7.6Kg; and body fat 17.8±5.2%) participated of the study. The CV was measured through four different intensities of running accomplished until exhaustion (tlim), it pre-adjusted to occur between 2 and 10 minutes (speed between 15km.h-1 and 21km.h-1). The CV was determined by three mathematical models, two by linear relations (velocity versus inverse of time - VCVx1/tlim; and distance versus time relations - VCDxT) and one by hyperbolic relation (time versus velocity - VCH). The AnT was determined from incremental test on treadmill with initial speed at 7km.h-1 and increment of 1.5km.h-1 at each 3 minutes until voluntary exhaustion. Immediately after each exercise stage were collect blood samples from ear lobe to measure of lactatemia. The AnT corresponded to abrupt increase of the lactate concentration response using bi-segmented linear regression (AnTBI). The three VC determinations corresponded to 13.48±0.91km.h-1 (VCVx1/tlim), 13.04±1.12km.h-1 (VCDxT) and 12.83±0.78km.h-1 (VCH) and only the VCVx1/tlim showed statistically different of the AnTBI (12.06±1.99km.h-1). However, these VC results overestimate the speedy of AnTBI in 11.84±1.30%, 7.7±1.3% and 5.83±1.04%, respectively. Significant correlation was not found among the three VC and the AnTBI. Thus, the CV determined by three conventional models seem not be a good tool for AnT prediction in armed forces soldiers at running

Metabolic Profile And Spontaneous Physical Activity Modulation Under Short-term Food Restriction In Young Rats.

The aim of this study was to investigate the effects of short-term food restriction (6-weeks) on metabolic profile and spontaneous physical activity (SPA) of young male Wistar rats. METHODS Thirty rats had their baseline SPA measured at 21 days-old and were separated into two groups at 28 days-old: Control (CG) and 50% of food restriction (FR). The food restriction protocol lasted six weeks, being the SPA measured weekly by a gravimetric apparatus. At the end of the experiment, biochemical analyses were performed in serum and tissue samples with statistical significance set at 5%. RESULTS FR showed less SPA than CG, as occurred for body mass, water intake, adipose tissue and liver, heart and soleus glycogen, serum glucose, total protein, triglycerides and total cholesterol (P<0.05). CONCLUSION Data set demonstrates that low substrate stores signaled to decrease spontaneous physical activity to save energy.23especia

Melatonin has an ergogenic effect but does not prevent inflammation and damage in exhaustive exercise

It is well documented that exhaustive physical exercise leads to inflammation and skeletal muscle tissue damage. With this in mind, melatonin has been acutely administered before physical exercise; nevertheless, the use of melatonin as an ergogenic agent to prevent tissue inflammation and damage remains uncertain. We evaluated the effects of melatonin on swimming performance, muscle inflammation and damage and several physiological parameters after exhaustive exercise at anaerobic threshold intensity (iLAn) performed during light or dark circadian periods. The iLAn was individually determined and two days later, the animals performed an exhaustive exercise bout at iLAn 30 minutes after melatonin administration. The exercise promoted muscle inflammation and damage, mainly during the dark period and the exogenous melatonin promoted a high ergogenic effect. The expressive ergogenic effect of melatonin leads to longer periods of muscle contraction, which superimposes a possible melatonin protective effect on the tissue damage and inflammation5CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP305650/2009- 22009/08535-5; 2011/13226-1; 2012/20501-

Assessment of aerobic capacity through blood and ventilatory responses in four different ergometers

The objective of the study was to compare intensities of respiratory compensation point (RCP), anaerobic threshold at onset blood lactate accumulation (OBLA3,5), and anaerobic threshold at lactate abrupt increase (AnT LAC) determined in four different ergometers. Hence, eleven table tennis players (19±1 years) performed graded exercise tests on cycle ergometer, arm cranking ergometer, treadmill and specific table tennis test. The respiratory response and lactatemia were measured during the tests. We did not find significant differences among RCP, AnT LAC and OBLA3,5 in arm cranking ergometer (63.4±4.8W, 66.9±4.5W and 64.5±6.1W, respectively), treadmill (11.4±0.4km.h-1, 11.3±0.3km.h-1 and 11.1±0.3km.h-1, respectively), and specific table tennis test (40.5±1.8bolas.min-1, 42.6±3.6bolas.min-1 and 42.8±5.6bolas.min-1, respectively). However, the OBLA3,5 (131.9±6.6W) was significantly lower than RCP (149.3±4.9W) and AnT LAC (149.3±4.7W) in the cycle ergometer. Strong and significant correlation coefficients were found in the specific test for all methods (r range 0.83 to 0.95), in arm cranking ergometer between RCP and OBLA3,5 (r=0.78), and on treadmill running between OBLA3,5 and AnT LAC (r=0.76). Therefore, we conclude that RCP, OBLA3,5 and AnT LAC seem to correspond to the same physiological phenomenon, mostly during specific table tennis test.O objetivo do presente estudo foi comparar as intensidades do ponto de compensação respiratório (PCR), limiar anaeróbio de concentração fixa (OBLA3,5) e limiar anaeróbio de lactato de aumento abrupto lactacidêmico (LAnLAC) determinadas em diferentes ergômetros. Para isso, onze mesatenistas (19±1 anos) realizaram testes incrementais máximos no cicloergômetro, ergômetro de braço, esteira e em teste específico para o tênis de mesa. Durante esses esforços, foram mensuradas as repostas lactacidêmica e respiratória. Na análise intraergômetro, não foram encontradas diferenças significativas entre o PCR, LAnLAC e OBLA3,5 no ergômetro de braço (63,4±4,8W, 66,9±4,5W e 64,5±6,1W, respectivamente), esteira (11,4±0,4km.h-1, 11,3±0,3km.h-1 e 11,1±0,3km.h-1, respectivamente) e teste específico (40,5±1,8bolas.min-1, 42,6±3,6bolas.min-1 e 42,8±5,6bolas.min-1, respectivamente); apenas no cicloergômetro foi verificado menor valor de OBLA3,5 (131,9±6,6W) em relação ao PCR (149,3±4,9W) e o LAnLAC (149,3±4,7W). No entanto, fortes e significativas correlações foram verificadas no teste específico entre todos esses métodos (r entre 0,83 a 0,95), entre o PCR e OBLA3,5 no ergômetro de braço (r=0,78) e entre OBLA3,5 e LAnLAC na esteira (r=0,76). Desse modo, podemos concluir que o PCR, OBLA3,5 e LAnLAC parecem corresponder ao mesmo fenômeno fisiológico, principalmente, no teste específico para o tênis de mesa.35036

Efeito da luminosidade e do horário do exercício de natação até a exaustão na intensidade de lactato mínimo sobre respostas bioquímicas e hematológicas de ratos

O modelo experimental com o uso de ratos tem sido largamente empregado na produção do conhecimento científico em diversos campos. O exercício físico é uma das intervenções utilizadas, sendo que atualmente, com o controle da intensidade relativa de esforço, podemos aprofundar essas investigações. Sabendo que o rato possui hábitos noturnos, algumas características cronobiológicas devem ser consideradas, como a temperatura corporal e atividade espontânea elevada no ciclo escuro do dia. Porém, investigações acerca do horário de manipulação em biotério e aplicação de testes físicos não têm levado em consideração o fator cronobiológico, assim, o objetivo da presente dissertação foi identificar se o exercício físico agudo ou a manipulação crônica de ratos em dois horários distintos do dia são capazes de influenciar a determinação da intensidade correspondente ao teste de lactato mínimo (ILM), o tempo limite sob esta intensidade (TTELMi) e/ou o perfil hematológico e bioquímico de ratos submetidos a exercício de natação. Para isso, 80 ratos Wistar foram distribuídos aleatoriamente em quatro grupos, compondo dois grupos controle (12:00 h e 20:00 h) e dois experimentais que realizaram o teste de performance (12:00 h e 20:00 h). A manipulação e testes de exercício foram aplicados no horário estipulado. Aos 90 dias de idade, todos os animais foram submetidos ao teste de lactato mínimo (TLM). Respeitado um intervalo de 48 horas, os grupos experimentais realizaram o tLIM, sendo eutanasiados em câmara de CO2 imediatamente após tal procedimento (em repouso no mesmo horário para os grupos controle). Para os testes realizados no período noturno foi utilizada uma iluminação especial, buscando a mínima influência no mínimo o ciclo circadiano dos animais. Foi extraído sangue por punção cardíaca, além de...The experimental model using rats has been widely applied to scientific knowledge production in many fields. The exercise has been an interventions used, and currently, with the individual effort intensity control, we can deepen these investigations. Knowing that the rat possess nocturnal habits, some chronobiological characteristics must be considered, such as body core temperature and spontaneous activity level to be higher in the dark cycle of day. However, the time of day of exercise tests and handling have not taken into account, thus, the aim of this investigation was to identify if acute exercise or chronic handling at different times of day can influence the determination of the intensity corresponding to Lactate Minimum Test (ILM), the time to exhaustion under this intensity (TTELMi) and/or hematologic and biochemical parameters of rats submitted to swimming exercise. For this, 80 Wistar rats were randomly divided into four groups, comprising two control (12:00 h and 20:00 h) and two experimental groups (12:00 h and 20:00 h). All handling and exercise tests were performed on determined time. At 90 days old, all animals performed lactate minimum test (TLM), and 48 h after, experimental groups performed the tLIM, being euthanized in CO2 immediately after this procedure (at rest at the same hour for control groups). To nocturnal tests was used a special illumination, intending to cause the minimum influence on the circadian cycle of animals. Blood sample was drawn by cardiac puncture. Liver and skeletal muscle tissue samples, as blood samples, were used to perform biochemical and hematological analysis. The results are arranged in four experiments, with the first testing the mathematical or non math procedure to determining the intensity and lactatemia corresponding to the TLM, being suggested the use of second... (Complete abstract click electronic access below)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Ergogenic response of melatonin ar nadir and acrophase of spontaneous activity and its consequences on IKK/NF-kB pathway activity and muscle tissue damage

Orientador: Claudio Alexandre GobattoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Educação FísicaResumo: Sintetizada principalmente na glândula pineal de mamíferos, a melatonina é uma indoleamina responsável classicamente por sincronizar o ritmo circadiano prioritariamente por meio do ciclo geofísico terrestre de luminosidade. A identificação de diversas outras propriedades a tornou alvo recente de estudos que buscam conhecer seus efeitos sobre o exercício físico. Otimizar o uso de substratos energéticos durante o esforço, inibir inflamação e lesões teciduais exacerbadas são propriedades documentadas na literatura e consideradas como potencialmente ergogênicas, fato que compreende um capítulo controverso da atual literatura científica esportiva. Diante disso, o objetivo da tese foi determinar a capacidade ergogênica da melatonina em exercício exaustivo sob intensidade de máxima capacidade aeróbia (tlim) iniciados no nadir e acrofase da atividade espontânea (AE), identificando os efeitos dessas condições sobre a atividade da via inflamatória IKK/NF-'capa'B em músculo esquelético oxidativo, marcadores metabólicos, hematológicos e de lesão tecidual de ratos nadadores. Para isso, dois procedimentos foram originalmente padronizados: i) construção de aparato e confecção de rotina de cálculos para a determinação do ritmo circadiano da AE e ii) teste incremental (TI) para estimativa da intensidade de máxima capacidade aeróbia de ratos nadadores. Os animais foram mantidos sob condições ambientais adequadas e sob ciclo claro/escuro de 12 horas iniciando às 06:00h com luz clara (560nm; 60lux). A determinação da AE ao longo do dia foi utilizada para definição dos horários em que seriam iniciados todos os procedimentos, sendo nadir e acrofase desta variável correspondentes a 12:00 (ZT 6) e 20:00h (ZT 14), respectivamente. Ratos machos albinos da linhagem Wistar foram distribuídos aleatoriamente em grupos para aplicação do TI iniciando nestes momentos do dia, aos 90 dias de idade. Para os testes conduzidos no período noturno foi empregada luminosidade especial afim de minimizar a influência da luz na secreção fisiológica da melatonina (>600nm; 600nm; <15lux). At 92 days-old a solution with or with no exogenous melatonin (10 mg.kg-1, I.P.) were administered to rats that were or not submitted to tlim 30 minutes after. Euthanasia was conducted one hour after tlim to biological material withdraw. Laboratory techniques of Western Blotting and ELISA were employed, and commercial kits and biochemical techniques. Melatonin significantly increases the tolerance to the proposed exercise, however, post hoc assumptions showed significant differences only between animals that assessments begun at SPA acrophase, when endogenous melatonin is usually higher in nocturnal rats. Significantly higher inflammatory and tissue damage markers were found to exercised animals assessed at wakefulness period (higher SA) that received exogenous melatonin, where were also found higher tlim. Thus, the massive ergogenic effect of melatonin leads to higher periods of muscle contraction, which superimposed melatonin protective effect on the tissue damage and its anti-inflammatory action. The proposed exercise resembles cyclic long duration sports, as marathons. However, direct inferences between models should be carefully conducted once the Human Being presents wakefulness period during daily hours, when melatonin is found at lower concentrations, so, the interpretation of melatonin action may differ between species.DoutoradoBiodinamica do Movimento HumanoDoutor em Educação Físic

Repeated sprint ability tests and intensity-time curvature constant to predict short-distance running performances

Anaerobic efforts are commonly required through repeated sprint during efforts in many sports, making the anaerobic pathway a target of training. Nevertheless, to identify improvements on such energetic way it is necessary to assess anaerobic capacity or power, which is usually complex. For this purpose, authors have postulated the use of short running performances to anaerobic ability assessment. Thus, the aim of this study was to find a relationship between running performances on anaerobic power, anaerobic capacity or repeated sprint ability. Methods Thirteen military performed maximal running of 50 (P50), 100 (P100) and 300 (P300) m on track, beyond of running-based anaerobic sprint test (RAST; RSA and anaerobic power test), maximal anaerobic running test (MART; RSA and anaerobic capacity test) and the W′ from critical power model (anaerobic capacity test). Results By RAST variables, peak and average power (absolute and relative) and maximum velocity were significantly correlated with P50 (r = −0.68, p = 0.03 and −0.76, p = 0.01; −0.83, p < 0.01 and −0.83, p < 0.01; and −0.78, p < 0.01), respectively. The maximum intensity of MART was negatively and significantly correlated with P100 (r = −0.59) and W′ was not statistically correlated with any of the performances. Conclusion MART and W′ were not correlated with short running performances, having a weak performance predicting probably due to its longer duration in relation to assessed performances. Observing RAST outcomes, we postulated that such a protocol can be used during daily training as short running performance predictor