Mild to moderate overweight in dogs: is there an impact on routine hematological and biochemical profiles, echocardiographic parameters and cardiac autonomic modulation?

Obesity is considered the most common nutritional disease of dogs. Even though overt obesity is more likely to impair health, even moderately overweight dogs are at greater risk for requiring medication for chronic health problems earlier in life. Although the number of overweight dogs far exceeds the number of obese ones, most of the studies published so far focused on derangements in a mixed overweight/obese population (Body condition score - BCS ≥7/9) rather than in separated groups. This study aimed to evaluate the impact of mild to moderate obesity on routine hematological and biochemical profile and cardiovascular parameters in dogs. Nine healthy lean (BCS =4-5/9) and 24 overweight dogs (BCS = 6-7/9) were enrolled. Complete blood count, serum biochemistry analyses, echocardiographic parameters, and cardiac autonomic function by heart rate variability (HRV) were determined. In our study population, although total protein, globulin and phosphorus concentrations were increased in overweight compared to lean dogs, all complete blood count and biochemical parameters were within reference ranges for both groups. Parameters usually increased in obese dogs, like triglycerides and cholesterol concentrations, were within reference ranges in our overweight population. There were no significant changes in echocardiographic parameters, but HRV had a significant decrease in high frequency (HF) power (P = 0.02), suggesting a depression in parasympathetic activity. Our findings show that mild to moderate overweight dogs do not show the hematological and echocardiographic alterations already reported for mixed overweight/obese populations but might have impaired cardiac autonomic modulation. Although not enough to make conclusions, our data raise the question of whether research studies should place overweight and obese dogs in the same category.

Cardiovascular and Autonomic Responses after a Single Bout of Resistance Exercise in Men with Untreated Stage 2 Hypertension.

The aim of this paper is to assess the integrated responses of ambulatory blood pressure (BP), cardiac autonomic modulation, spontaneous baroreflex sensitivity (BRS), and vascular reactivity after a single bout of resistance exercise (RE) in men with stage 2 hypertension who have never been treated before. Ten hypertensive men were subjected to a RE session of three sets of 20 repetitions and an intensity of 40% of the 1-repetition maximum (RM) test in seven different exercises. For the control (CTR) session, the volunteers were positioned on the exercise machines but did not perform any exercise. Forearm blood flow was measured by venous occlusion plethysmography. We also analyzed the heart rate variability (HRV), ambulatory BP, blood pressure variability (BPV), and BRS. All measurements were performed at different timepoints: baseline, 20 min, 80 min, and 24 h after both RE and CTR sessions. There were no differences in ambulatory BP over the 24 h between the RE and CTR sessions. However, the area under the curve of diastolic BP decreased after the RE session. Heart rate (HR) and cardiac output increased for up to 80 and 20 min after RE, respectively. Similarly, forearm blood flow, conductance, and vascular reactivity increased 20 min after RE (p < 0.05). In contrast, HRV and BRS decreased immediately after exercise and remained lower for 20 min after RE. We conclude that a single bout of RE induced an increase in vascular reactivity and reduced the pressure load by attenuating AUC of DBP in hypertensive individuals who had never been treated with antihypertensive medications.

Modulation of cardiac renin-angiotensin system, redox status and inflammatory profile by different volumes of aerobic exercise training in obese rats.

Overactivation of the classical arm of the renin-angiotensin (Ang) system (RAS) occurs during inflammation, oxidative stress and obesity-induced cardiomyopathy. The activation of the protective arm of RAS may act to counterbalance the deleterious effects of the classical RAS. Although aerobic exercise training (AET) shifts the balance of the RAS towards the protective arm, little is known about the molecular adaptations to different volumes of AET. The aim of this study was to evaluate the impact of AET volume on the modulation of RAS, as well as on cardiac biomarkers of oxidative stress and inflammation, in a diet-induced obesity model. Male Wistar rats were fed either control (CON) or high fat (HF) diet for 32 weeks. At week 20, HF group was subdivided into sedentary, low (LEV, 150 min/week) or high (HEV, 300 min/week) exercise volume. After 12 weeks of exercise, body mass gain, systolic blood pressure and heart rate were evaluated, as well as RAS, oxidative stress and inflammation in the heart. Body mass gain, systolic blood pressure and heart rate were higher in HF group when compared with SC group. Both trained groups restored systolic blood pressure and heart rate, but only HEV reduced body mass gain. Regarding the cardiac RAS, the HF group exhibited favoring of the classical arm and both trained groups shifted the balance towards the counterregulatory protective arm. The HF group had higher B1R expression and lower B2R expression than the control group, and B2R expression was reverted in both trained groups. The HF group also presented oxidative stress. The LEV and HEV groups improved the cardiac redox status by reducing Nox 2 and nitrotyrosine expression, but only the LEV group was able to increase the antioxidant defense by increasing Nrf2 signaling. While the HF group presented higher TNF-α, IL-6 and NFκB expression, and lower IL-10 expression, than the SC group, both training protocols improved the inflammatory profile. Although both trained groups improved the deleterious changes related to obesity cardiomyopathy, it is clear that the molecular mechanisms differ between them. Our results suggest that different exercise volumes might reach different molecular targets, and this could be a relevant factor when using exercise to manage obesity.

Exercise-induced cardiac opioid system activation attenuates apoptosis pathway in obese rats.

AIM: To compare the effect of 150 min vs. 300 min of weekly moderate intensity exercise training on the activation of the opioid system and apoptosis in the hearts of a diet-induced obesity model. METHODS: Male Wistar rats were fed with either control (CON) or high fat (HF) diet for 32 weeks. At the 20th week, HF group was subdivided into sedentary, low (LEV, 150 min·week-1) or high (HEV, 300 min·week-1) exercise volume. After 12 weeks of exercise, body mass gain, adiposity index, systolic blood pressure, cardiac morphometry, apoptosis biomarkers and opioid system expression were evaluated. RESULTS: Sedentary animals fed with HF presented pathological cardiac hypertrophy and higher body mass gain, systolic blood pressure and adiposity index than control group. Both exercise volumes induced physiological cardiac hypertrophy, restored systolic blood pressure and improved adiposity index, but only 300 min·week-1 reduced body mass gain. HF group exhibited lower proenkephalin, PI3K, ERK and GSK-3ß expression, and greater activated caspase-3 expression than control group. Compared to HF, no changes in the cardiac opioid system were observed in the 150 min·week-1 of exercise training, while 300 min·week-1 showed greater proenkephalin, DOR, KOR, MOR, Akt, ERK and GSK-3ß expression, and lower activated caspase-3 expression. CONCLUSION: 300 min·week-1 of exercise training triggered opioid system activation and provided greater cardioprotection against obesity than 150 min·week-1. Our findings provide translational aspect with clinical relevance about the critical dose of exercise training necessary to reduce cardiovascular risk factors caused by obesity.

Analysis between two optical biometric devices in patients with cataract / Análise entre dois dispositivos de biometria óptica em pacientes com catarata

ABSTRACT Objective: To evaluate the correlation of optical biometry and target with variable ages, anterior chamber depth, axial length, R1/K1 and R2/K2 established by two optical biometry devices in patients with cataract. Methods: The study included the analysis of 348 medical records, from which 503 cataract eyes were selected, which underwent evaluation by the optical biometric devices IOL Master 700 and Lenstar LS 900 in the period of April to July 2017. Data collected were: age, anterior chamber depth, axial length, R1/K1 and R2/K2. Results: The average of the biometrics obtained using Lenstar was 21.02, varying 3.46, more or less, with an average target of -0.02, varying 0.45. In relation to the IOL Master it was 21.19, with a variation of 3.40 and average target of -0.01, a variation of 0.11. It can be observed that despite close values in relation to the mean, there was significance (p<0.001). Axial length (p<0.001) and R1/K1 (p<0.001) had an influence on the difference of the biometric values between the devices. Conclusion: A high degree of clinical and statistical correspondence was observed between the results obtained by the biometry devices in patients with cataract.

RESUMO Objetivos: Avaliar a correlação da biometria óptica e target com as variáveis idade, profundidade da câmara anterior, comprimento axial, R1/K1 e R2/K2 estabelecidos por dois dispositivos de biometria óptica em pacientes com catarata. Métodos: O trabalho abrangeu a análise de 348 prontuários dos quais foram selecionados 503 olhos com catarata ,que passaram pela avaliação nos dispositivos de biometria óptica IOL Master 700 e Lenstar LS 900 no período de abril a julho de 2017. Os dados colhidos foram: idade, profundidade da câmara anterior, comprimento axial, R1/K1 e R2/K2 . Resultados: A média da biometria obtida utilizando o Lenstar foi de 21,02, variando 3,46 para mais ou para menos, com target médio de -0,02, variando 0,45. Já em relação ao IOL Master foi de 21,19, com variação de 3,40 e target médio de -0,01, variação de 0,11. Pode-se observar que apesar de valores próximos em relação à média, houve significância (p < 0,001). Houve a concordância da biometria em relação ao comprimento axial (p < 0,001) e R1/K1(p < 0,001). Conclusão: Observou-se alto grau de correspondência clínica e estatística entre os resultados obtidos pelos dispositivos de biometria em pacientes com catarata.

Exercise training dose differentially alters muscle and heart capillary density and metabolic functions in an obese rat with metabolic syndrome.

NEW FINDINGS: What is the central question of this study? Regular exercise is recommended as a non-pharmacological approach for the prevention and treatment of metabolic syndrome. However, the impact of different combinations of intensity, duration and frequency of exercise on metabolic syndrome and microvascular density has not been reported. What is the main finding and its importance? We provide evidence on the impact of aerobic exercise dose on metabolic and microvascular alterations in an experimental model of metabolic syndrome induced by high-fat diet. We found that the exercise frequency and duration were the main factors affecting anthropometric and metabolic parameters and microvascular density in the skeletal muscle. Exercise intensity was related only to microvascular density in the heart. We evaluated the effect of the frequency, duration and intensity of exercise training on metabolic parameters and structural capillary density in obese rats with metabolic syndrome. Wistar-Kyoto rats were fed either a standard commercial diet (CON) or a high-fat diet (HFD). Animals that received the HFD were randomly separated into either a sedentary (SED) group or eight different exercise groups that varied according to the frequency, duration and intensity of training. After 12 weeks of aerobic exercise training, the body composition, aerobic capacity, haemodynamic variables, metabolic parameters and capillary density in the heart and skeletal muscle were evaluated. All the exercise training groups showed reduced resting systolic blood pressure and heart rate and normalized fasting glucose. The minimal amount of exercise (90 min per week) produced little effect on metabolic syndrome parameters. A moderate amount of exercise (150 min per week) was required to reduce body weight and improve capillary density. However, only the high amount of exercise (300 min per week) significantly reduced the amount of body fat depots. The three-way ANOVA showed a main effect of exercise frequency and duration for the improvement of metabolic syndrome and capillary density in skeletal muscle. Exercise intensity was a main factor in reversing microvascular rarefaction in the heart.

High, but not low, exercise volume shifts the balance of renin-angiotensin system toward ACE2/Mas receptor axis in skeletal muscle in obese rats.

Metabolic syndrome is a cluster of metabolic risk factors that is linked to central obesity, elevated blood pressure, insulin resistance (IR), and dyslipidemia, where the renin-angiotensin system (RAS) may provide a link among them. This study aimed to evaluate volume exercise effects comparing low vs. high volume of chronic aerobic exercise on RAS axes in skeletal muscle in a diet-induced obesity (DIO) rat model. For this, male Wistar-Kyoto rats were fed a standard chow (SC) diet or a high-fat (HF) diet for 32 wk. Animals receiving the HF diet were randomly divided into low exercise volume (LEV, 150 min/wk) and high exercise volume (HEV, 300 min/wk) at the 20th week. After 12 wk of aerobic treadmill training, the body mass and composition, blood pressure, glucose and lipid metabolism, RAS axes, insulin signaling, and inflammatory pathway were performed. HEV slowed the body mass gain, reduced intra-abdominal fat pad and leptin levels, improved total and peripheral body composition and inflammatory cytokine, reduced angiotensin II type 1 receptor expression, and increased Mas receptor protein expression compared with the HF animals. Sedentary groups (SC and HF) presented lower time to exhaustion and maximal velocity compared with the LEV and HEV groups. Both exercise training groups showed reduced resting systolic blood pressure and heart rate, improved glucose tolerance, IR, insulin signaling, and lipid profile. We conclude that the HEV, but not LEV, shifted the balance of RAS toward the ACE2/Mas receptor axis in skeletal muscle, presenting protective effects against the DIO model.

Physical exercise restores microvascular function in obese rats with metabolic syndrome.

BACKGROUND: Obesity and metabolic syndrome are related to systemic functional microvascular alterations, including a significant reduction in microvessel density. The aim of this study was to investigate the effects of exercise training on functional capillary density in the skeletal muscle and skin of obese rats with metabolic syndrome. METHODS: We used male Wistar-Kyoto rats that had been fed a standard commercial diet (CON) or high-fat diet (HFD) for 32 weeks. Animals receiving the HFD were randomly divided into sedentary (HFD+SED) and training groups (HFD+TR) at the 20(th) week. After 12 weeks of aerobic treadmill training, the maximal oxygen uptake (VO2max); hemodynamic, biochemical, and anthropometric parameters; and functional capillary density were assessed. In addition, a maximal exercise test was performed. RESULTS: Exercise training increased the VO2max (69 ± 3 mL/kg per min) and exercise tolerance (30 ± 1 min) compared with the HFD+SED (41 ± 6 mL/kg per min, P < 0.05 and 16 ± 1 min, P < 0.001) and with the CON (52 ± 7 mL/kg per min and 18 ± 1 min, P < 0.05) groups. The HFD+TR group also showed reduced retroperitoneal fat (0.03 ± 0.00 vs. 0.05 ± 0.00 gram/gram, P < 0.001), epididymal fat (0.01 ± 0.00 vs. 0.02 ± 0.00 gram/gram, P < 0.001), and systolic blood pressure (127 ± 2 vs. 150 ± 2 mmHg, P<0.001). The HFD+TR group also demonstrated improved glucose tolerance, as evaluated by an intraperitoneal glucose tolerance test, fasting plasma glucose levels (5.0 ± 0.1 vs. 6.4 ± 0.2 mmol/L, P<0.001) and fasting plasma insulin levels (26.5 ± 2.3 vs. 38.9 ± 3.7 µIU/mL, P < 0.05). Glucose tolerance did not differ between HFD+TR and CON groups. Exercise training also increased the number of spontaneously perfused capillaries in the skeletal muscle (252 ± 9 vs. 207 ± 9 capillaries/mm(2)) of the training group compared with that in the sedentary animals (260 ± 15 capillaries/mm(2)). CONCLUSIONS: These results demonstrate that exercise training reverses capillary rarefaction in our experimental model of metabolic syndrome and obesity.

Efeito da frequência, da duração e da intensidade do exercício físico crônico sobre os parâmetros da síndrome metabólica e microcirculação em ratos obesos / Effect of frequency, duration and intensity of chronic exercise on the parameters of the metabolic syndrome and microcirculation in obese mice

A Síndrome Metabólica (SM) é definida por um conjunto de anormalidades metabólicas, incluindo obesidade central, tolerância diminuída à glicose, dislipidemia e hipertensão. A prevalência da SM aumenta com aidade e é associada com o maior risco de desenvolvimento de diabetes e doenças cardiovasculares. A interação de uma predisposição poligenética com influências ambientais, como ingestão excessiva de gordura, calorias e estilo de vida sedentário, são os responsáveis pelo aumento destas anormalidades. Vários estudos demonstraram a capacidade do exercício em reverter diversos fatores de risco associados com a SM. Contudo, o nível ótimo de exercício necessário para prevenir e tratar essas anormalidades ainda não está completamente definido.Nós estudamos o efeito da duração da sessão de treinamento, do número de sessões semanais e da intensidadedo exercício físico sobre os parâmetros metabólicos, hipertensão e a microcirculação de ratos obesos. Os experimentos foram realizados em ratos Wistar Kyotomachos, alimentados com dieta comercial padrão (CON) ou dieta hiperlipídica (HFD) por 32 semanas. Os animais que receberam dieta HFD foram randomicamente separados em grupo sedentário (HFD + SED), e em 8 grupos de treinamento, distribuídos pela frequência semanal de treinamento (3 ou 5 vezes), duração da sessão (30 ou 60 minutos) e pela intensidade do treinamento (60 ou 80% do Teste Incremental Máximo), sendo: 1) HFD + TR 3.30.60; 2) HFD + TR 3.30.80; 3) HFD + TR 3.60.60; 4) HFD + TR 3.60.80; 5) HFD + TR 5.30.60; 6) HFD + TR 5.30.80; 7) HFD + TR 5.60.60; 8) HFD + TR 5.60.80...

Após 12 semanas de treinamento aeróbio em esteira ergométrica foram avaliadas as variáveisdo teste incremental máximo (tempo de exaustão, distância total percorrida, velocidade máxima e consumo máximo de oxigênio), parâmetros hemodinâmicos (pressão arterial sistólica (PAS) e frequência cardíaca de repouso (FC)), parâmetros metabólicos (peso corporal, % de gordura corporal, peso da gordura epididimal e retroperitoneal, colesterol total, triglicerídeos eteste intraperitoneal de tolerância à glicose). O treinamento aumentou a tolerância ao exercício e reduziu a PAS,FC, diâmetro dos adipócitos e depósitos de gordurano hepatócito nos grupos de treinamento. Uma significativa redução na glicose sanguínea foi detectada somente nos grupos que treinaram 5 vezes na semana e os depósitos de gordura (epididimal, retroperitoneal e gordura total determinada através do DEXA) foram significativamente reduzidos somente nos grupos 5.60.60 e 5.60.80. Na microcirculação, apesar de uma nítida redução na densidade capilar funcional dos animais que ingerirama HFD (cerca de 16% no músculo esquelético e 12% na pele,quando comparados ao grupo CON) e da melhoria desta condição através do exercício, nenhuma diferença significativa foi constatada tanto no músculo grácil quanto na pele. Nossos achados indicam que o exercício é efetivo na redução dos parâmetros hemodinâmicos, diâmetro do adipócito e esteatose hepática em qualquer frequência, volume e intensidade usada neste estudo. Além disso, nós demonstramos que o controle glicêmico é altamente dependente da frequência do exercício, assim como a utilização de maiores cargas de treinamento (alta frequência e grande volume) é requerida para reduziros depósitos de gordura corporal...

Efeito da ingestão de cafeína sobre os parâmetros da potência crítica / 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.

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.

A influência de diferentes distâncias na determinação da velocidade crítica em nadadores / The influence of different distances on determination of critical velocity in swimmers

O objetivo do presente estudo foi verificar a influência da utilização de diferentes combinações de distâncias sobre os valores da Velocidade Crítica (VC) e Capacidade de Trabalho Anaeróbio (CTAn). Participaram do estudo dezenove nadadores com experiência em treinamento na modalidade. A VC foi determinada através do coeficiente angular da reta de regressão linear entre a distância e o tempo obtido em cada repetição. Para a determinaçãoda VC, foram utilizadas cinco distâncias (50, 100, 200, 400 e 800m) com intervalo de 24 horas entre elas. Posteriormente, foram feitas quatro combinações entre as distâncias: VC1 (50, 100 e 200m), VC2 (100, 200 e 400m), VC3 (200, 400 e 800m) e VC4 (50, 100, 200, 400 e 800m). O teste de Shapiro-Wilk foi utilizado para determinar a normalidade das amostras. Para comparações entre a VC e as diferentes combinações de tiros, utilizou-se ANOVA one way (p<0,05). A combinação com distâncias menores (VC1) proporcionou maiores valores da VC (1,47 ± 0,13), causando com isso uma diminuição na CTAn (11,91 ± 2,61). A utilização de tiros de média e longa distância proporcionou um valor mais baixo para a VC (1,38 ± 0,10, 1,34 ± 0,09 e 1,36 ± 0,09) e maior para a CTAn (19,84 ± 6,74, 27,44 ± 6,91 e 18,43 ± 5,21) quando comparados com os tiros curtos, respectivamente para VC2, VC3 e VC4. Através dos dados obtidos, conclui-se que a distância dos tiros possui grande influência sobre os valores da VC e da CTAn, podendo com isso superestimar ou subestimar a velocidade correspondente à máxima fase estável do lactato.

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.

Efeito da ingestão de cafeína sobre o limiar de esforço percebido (LEP) / Effect of ingestion of caffeine on perceived exertion threshold (PET)

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 ciclo ergômetro, 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 menor que 0,01), e os testes de 80 e 100% apresentaram menor taxa de aumento da percepção subjetiva de esforço (PSE) (P menor que 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%.

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 smaller that 0,01) and the tests between 80% and 100% presented lower increasing ratings of perceived exertion (RPE) (P smaller that 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.