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Objective: To conduct a longitudinal investigation of cardiac vagal activity (CVA) by measuring resting HR and calculating the cardiac vagal index (CVI) in individuals undergoing sympathectomy for the treatment of primary hyperhidrosis., Methods: This was a descriptive longitudinal study involving 22 patients, 13 of whom were female. The mean age was 22.5 ± 8.8 years. The palms, soles, and axillae were the most commonly affected sites. Resting HR was measured by an electrocardiogram performed 20 min before the 4-second exercise test (4sET), which was used in order to evaluate CVA at three different time points: before surgery, one month after surgery, and four years after surgery., Results: Resting HR (expressed as mean ± SE) was found to have decreased significantly at 1 month after surgery (73.1 ± 1.6 bpm before surgery vs. 69.7 ± 1.2 bpm at one month after surgery; p = 0.01). However, the HR values obtained at four years after surgery tended to be similar to those obtained before surgery (p = 0.31). The CVI (expressed as mean ± SE) was found to have increased significantly at one month after surgery (1.44 ± 0.04 before surgery vs. 1.53 ± 0.03 at one month after surgery; p = 0.02). However, the CVI obtained at four years after surgery tended to be similar to that obtained before surgery (p = 0.10)., Conclusions: At one month after sympathectomy for primary hyperhidrosis, patients present with changes in resting HR and CVA, both of which tend to return to baseline at four years after surgery.

Background: Little has been studied on heart rate and its relationship with metabolic disorders., Objective: To identify possible association between heart rate (HR) and metabolic disorders in children and adolescents., Methods: This cross-sectional study evaluated 2.098 subjects, aged between 7 and 17 years. The variables evaluated were: HR, systolic (SBP) and diastolic blood pressure (DBP), pulse pressure (PP), double-product (DP), myocardial oxygen consumption (mVO2), lipids, glucose and uric acid levels, body mass index (BMI) and waist circumference (WC). The values of HR at rest and effort were divided into quartiles. The association between continuous values of HR and cardiometabolic indicators was tested by linear regression., Results: LDL cholesterol presented a significantly higher mean (p = 0.003) in schoolchildren with resting HR greater or equal to 91 bpm, compared to students with less than 75 bpm. Compared with the quartiles of effort HR, SBP, DBP, glucose and uric acid presented high values when HR was greater or equal than 185 bpm. SBP, glucose and HDL cholesterol demonstrated a significant association with resting HR. Uric acid was observed as a predictor of increased effort HR., Conclusion: Schoolchildren with a higher resting HR have higher mean of LDL cholesterol. For effort HR, there was an increase in blood pressure, glucose and uric acid levels. Uric acid has been shown to be a predictor of elevated effort HR.

Background:: High resting heart rate is considered an important factor for increasing mortality chance in adults. However, it remains unclear whether the observed associations would remain after adjustment for confounders in adolescents., Objectives:: To analyze the relationship between resting heart rate, blood pressure and pulse pressure in adolescents of both sexes., Methods:: A cross-sectional study with 1231 adolescents (716 girls and 515 boys) aged 14-17 years. Heart rate, blood pressure and pulse pressure were evaluated using an oscillometric blood pressure device, validated for this population. Weight and height were measured with an electronic scale and a stadiometer, respectively, and waist circumference with a non-elastic tape. Multivariate analysis using linear regression investigated the relationship between resting heart rate and blood pressure and pulse pressure in boys and girls, controlling for general and abdominal obesity., Results:: Higher resting heart rate values were observed in girls (80.1 ± 11.0 beats/min) compared to boys (75.9 ± 12.7 beats/min) (p ≤ 0.001). Resting heart rate was associated with systolic blood pressure in boys (Beta = 0.15 [0.04; 0.26]) and girls (Beta = 0.24 [0.16; 0.33]), with diastolic blood pressure in boys (Beta = 0.50 [0.37; 0.64]) and girls (Beta = 0.41 [0.30; 0.53]), and with pulse pressure in boys (Beta = -0.16 [-0.27; -0.04])., Conclusions:: This study demonstrated a relationship between elevated resting heart rate and increased systolic and diastolic blood pressure in both sexes and pulse pressure in boys even after controlling for potential confounders, such as general and abdominal obesity., Fundamento:: A frequência cardíaca de repouso é considerada um importante fator de aumento de mortalidade em adultos. Entretanto, ainda é incerto se as associações observadas permanecem após ajuste para fatores de confusão em adolescentes., Objetivos:: Analisar a relação entre frequência cardíaca de repouso, pressão arterial e pressão de pulso em adolescentes dos dois sexos., Métodos:: Estudo transversal com 1231 adolescentes (716 meninas e 515 meninos, idade de 14-17 anos). Frequência cardíaca, pressão arterial e pressão de pulso foram avaliadas com esfigmomanômetro oscilométrico validado para essa população. Peso e altura foram medidos com balança eletrônica e estadiômetro, respectivamente, e a circunferência abdominal, com uma fita inextensível. Análise multivariada com regressão linear investigou a relação entre frequência cardíaca de repouso, pressão arterial e pressão de pulso em meninos e meninas, controlando para obesidade geral e abdominal., Resultados:: Valores maiores de frequência cardíaca de repouso foram observados em meninas (80,1 ± 11,0 bpm) em comparação a meninos (75,9 ± 12,7 bpm) (p ≤ 0,001). Frequência cardíaca de repouso associou-se com pressão arterial sistólica em meninos [Beta = 0,15 (0,04; 0,26)] e meninas [Beta = 0,24 (0,16; 0,33)], com pressão arterial diastólica em meninos [Beta = 0,50 (0,37; 0,64)] e meninas [Beta = 0,41 (0,30; 0,53)], e com pressão de pulso apenas em meninos [Beta = -0,16 (-0,27; -0,04)]., Conclusões:: Este estudo demonstrou a relação da frequência cardíaca de repouso elevada com aumento das pressões arteriais sistólica e diastólica em ambos os sexos e com pressão de pulso em meninos, mesmo após controle para potenciais fatores de confusão, como obesidade geral e abdominal.

Objective: To determine the probability of oxygen desaturation in healthy individuals undergoing the incremental shuttle walk test (ISWT)., Methods: We enrolled 83 healthy subjects: 55 males (including 1 smoker) and 28 females. We determined pre-ISWT FEV1, FEV6, HR and SpO2, as well as post-ISWT HR and SpO2., Results: Mean values overall were as follows: age, 35.05 ± 12.53 years; body mass index, 24.30 ± 3.47 kg/m2; resting HR, 75.12 ± 12.48 bpm; resting SpO2, 97.96 ± 1.02%; FEV1, 3.75 ± 0.81 L; FEV6, 4.45 ± 0.87 L; FEV1/FEV6 ratio, 0.83 ± 0.08 (no restriction or obstruction); incremental shuttle walk distance, 958.30 ± 146.32 m; post-ISWT HR, 162.41 ± 18.24 bpm; and post-ISWT SpO2, 96.27 ± 2.21%. In 11 subjects, post-ISWT SpO2 was higher than was pre-ISWT SpO2. In 17 subjects, there was a 4% decrease in SpO2 after the ISWT. There were no statistically significant differences between the groups with and without post-ISWT oxygen desaturation in terms of age, gender, FEV1, FEV6, FEV1/FEV6, pre-ISWT SpO2, incremental shuttle walk distance, HR, or percentage of maximal HR. In the individuals with post-ISWT oxygen desaturation, the body mass index was higher (p = 0.01) and post-ISWT SpO2 was lower (p = 0.0001)., Conclusions: Healthy individuals can present oxygen desaturation after the ISWT. Using the ISWT to predict subtle respiratory abnormalities can be misleading. In healthy subjects, oxygen desaturation is common after the ISWT, as it is during any intense physical activity.

Unlabelled: Patients with dilated cardiomyopathy and implantable cardioverter-defibrillator (ICD) are a high-risk group for arrhythmias. They regularly undergo cardiopulmonary exercise testing (CPET) to assess cardiac reserve and to guide clinical decisions or therapeutic adjustments. Data from previous studies demonstrate that prognosis in patients with heart failure (HF) worsens with the presence of appropriate shocks., Objective: The purpose of this study was to evaluate the value of CPET parameters to predict shocks and other arrhythmic events in HF patients with ICD, in order to identify a high-risk group for arrhythmias., Methods: This was a prospective single-center registry of 61 consecutive patients (mean age 55 +/- 15 years, 18% female), with dilated cardiomyopathy (ischemic etiology in 57%) and ICD, who underwent symptom-limited maximal CPET six months or less before device implantation. Minimum follow-up was 180 days. The primary endpoint was appropriate shock and the composite endpoint was appropriate shock and/or ventricular fibrillation (VF) and/or sustained ventricular tachycardia (VT), which were then correlated with hemodynamic variables (heart rate and blood pressure) and CPET parameters., Results: During a mean follow-up of 27 months, eight patients died (13%), two of them from arrhythmic cause (3.3%), and 16 (26%) patients received at least one appropriate ICD shock, eight (13%) due to VF. Sustained VT was recorded in 23 patients (38%) and nonsustained VT in 42 patients (69%). CPET showed that the group with the primary end point had lower peak VO2, anaerobic threshold and chronotropic reserve. On multivariate analysis, resting heart rate was the only independent predictor of appropriate shock (HR 1.06; 95% CI 1.01-1.10; p = 0.025). Univariate analysis identified peak VO2, anaerobic threshold, VE/VCO2 slope, resting heart rate and heart rate decrease during the first minute of recovery, and systolic blood pressure during exercise as predictive of the composite endpoint (shock/VF/sustained VT). Multivariate analysis identified resting heart rate and peak VO2 as independent predictors, with HR 1.04; 95% CI 1.00-1.09 (p = 0.050) and HR 0.88; 95% CI 0.78-0.98 (p = 0.026), respectively. The best cut-off for resting heart rate to predict the composite and primary endpoints was > 76 bpm (area under the ROC curve: 0.67; 95% CI 0.53-0.78 and 0.65; 95% CI 0.51-0.76, respectively)., Conclusion: Resting heart rate and peak VO2 were identified in multivariate analysis as good predictors of arrhythmic events and resting heart rate was the only independent predictor of appropriate shock in HF patients with ICD. Both advanced stage heart failure and sympathetic overdrive may be associated with the development of malignant arrhythmias.

Background: Resting heart rate (which ranges from 60 to 80 bpm) is one of the simplest cardiovascular parameters, and has been considered as a predictor of cardiovascular and all-cause mortality., Objective: To determine the predictive value of resting heart rate (RHR) before exercise stress testing (ET) for cardiovascular (CV) and all-cause mortality., Methods: This was a case-control study using data from the database of the Exercise Testing Laboratory of a cardiac hospital and the death records of the Health Department of a city located in the South of Brazil from January 1995 to June 2007. A total of 7,055 patients were studied; 1,645 (23.3%) in the case group (deceased) and 5,410 (76.7%) in the control group (alive). The cut-off value of RHR for mortality was derived from the ROC curve, and a multivariate analysis was performed for the selected variables. The study's outcome measures were cardiovascular and all-cause mortality., Results: Six hundred and seventy-four patients died of cardiovascular diseases (9.5%); the cut-off value was RHR ≥ 78 bpm). After adjusting for selected variables, the odds ratio (OR) of RHR ≥ 78 bpm was 3.5 (95% CI 2.9 to 4.2) for CV mortality and 3.6 (95% CI 3.2 to 4.0) for all-cause mortality., Conclusion: Resting heart rate ≥ 78 is an independent predictor of cardiovascular and all-cause mortality.

Objective: The main objective of this study was to assess the influence of soy protein intake and weight training on resting energy expenditure (REE) in postmenopausal women., Methods: This 160-week clinical trial enrolled 60 women, with a mean age of 59 (7) years, allocated into four groups: G1 (soy protein plus exercise), G2 (placebo plus exercise), G3 (soy protein and no exercise) and G4 (placebo and no exercise). Soy protein and placebo (maltodextrin) were randomly distributed in powder form in servings of 25 grams/day. Ten weight exercises were performed, three times a week, with three sets of 8-12 repetitions per exercise per session, at a load of 60-80% of the one-repetition maximum (1RM). The REE was calculated from the O2 and CO2 values obtained by indirect calorimetry (Quinton QMC), performed for 30 minutes under controlled temperature and humidity. For statistical analysis, ANOVA, Student t test and multiple regression were performed with the Stata 9.2 software package. Significance was set at p<0.05., Results: The study sample was homogeneous with regard to all variables. Significant increases in REE (p <0.05) were detected in G1 (158 kcal/day, 17%) and G2 (110 kcal/day, 9%), whereas a 4% decrease was detected in G4 (p<0.05)., Conclusion: Weight training is a determining factor for increased resting energy expenditure in postmenopausal women. This effect can be boosted by dietary consumption of soy protein.

Background: Although studies have demonstrated the occurrence of postexercise hypotension (PEH) in resistance exercises, there is still no consensus on an ideal protocol., Objective: To evaluate the effects of different rest intervals (RI) between resistance exercise (RE) sets on postexercise blood pressure (BP)., Methods: Sixteen sedentary non-hypertensive young men performed three RE protocols with RI of 1 (P1), 2 (2) and 3 (P3) minutes between the sets, as well as a control protocol (CON), in a counterbalanced manner. The RE protocols consisted of three sets of eight repetitions in six exercises. The loads used in the 1st, 2nd, and 3rd exercise sets were 80%, 70% and 60% of one repetition maximum (1RM), respectively. Measurements were taken at rest (RES), 15 (T15), 30 (T30), 45 (T45), 60 (T60), 75 (T75), and 90 (T90) minutes after the session. Factorial analysis of variance (Anova) was carried out, followed by post hoc LSD., Results: No significant change was found in systolic BP after the protocols. A significant increase in diastolic BP was verified after CON at timepoints T45 and T90. Significant reduction in diastolic BP occurred after P1 and P3, with duration of 30 and 15 minutes, respectively. No significant differences were found in the systolic and diastolic BP responses between the protocols with different RI., Conclusion: RI does not seem to influence systolic BP reduction after an RE session. However, reductions in diastolic BP (P1 and P3) lasting up to 30 minutes were observed.

Purpose: To investigate the effects of L-carnitine supplementation, over thirty days, on the resting metabolic rate (RMR) and oxidation of free fatty acids (FFA) under rested or exercised conditions., Subjects and Methods: Twenty-one overweight active volunteers (40 to 58 years old) were randomized into two groups: supplemented (GS; N = 11; 1,8 g/day of L-carnitine) or placebo (GP; N = 10; maltodextrin). Caloric intake, anthropometry, RMR, VO(2max), respiratory exchange ratio and plasma FFA were measured., Results: No significant changes were found in the caloric intake (-244,66 vs. -126,00 kcal/day), body composition (-0.07 vs. -0.17 kg/m(2)), RMR (0.06 vs. -0.02 kcal/day), respiratory exchange ratio at rest (3.69 vs. -1.01) and exercise (0.01 vs. -0.01) or VO(2max) (0.50 vs. 1.25 mL/kg/min) between GS and GP. Plasma FFA levels were increased under resting conditions only in the GP group (0.27), but no significant changes were observed before or after physical activity in any of the groups., Conclusion: Supplementation with L-carnitine caused no changes in the variables analyzed in this study.

Background: Physical inactivity in adolescence is related to body fat accumulation, which apparently can increase the probability of onset and development of metabolic changes., Objective: To verify the predisposition to cardiovascular risk factors in adolescents with different levels of energy expenditure., Methods: A total of 108 young men and 132 young women aged between 12 and 16 years were selected. Daily energy expenditure was obtained using the questionnaire proposed by Bouchard et al. The sample was previously divided according to the quartiles of energy expenditure (Kcal/kg/day) into three groups: sedentary (SG), moderately active (MG), and active (AG). The enzyme-colorimetric method was used to determine the total cholesterol (TC), HDL-C, and triglycerides (TG) levels. LDL-C was calculated using the Friedewald et al's formula. The one-factor analysis of variance was used for statistical analysis, considering p<0.05., Results: For the male gender, significant differences were found between the groups for the TC variable (mg/dl); AG (121.56+/-19.15) was different from MG (142.70+/-27.65) and from SG (145.63+/-36.54). Likewise, MG was different from SG (F=3.70 and p=0.03). For the TG variable (mg/dl), AG (65.69+/-18.95) was different from MG (82.25+/-33.73) and from SG (97.44+/-45.95). Also, MG was different from SG (F=3.40 and p=0.04). For the female gender, no significant differences were found in relation to daily energy expenditure., Conclusion: More active young men show lower TC and TG levels in comparison with their moderately active and sedentary peers.

The aim of this study was to evaluate if obese women with the lowest values of caloric intake (CI) determined by food questionnaire also present the lowest values of resting metabolic rate (RMR), which could lead to excessive weight gain, caused by changes in energy balance. With this purpose, 77 obese women, with IMC>30 kg/m2, aged 20 to 45 years, had their physical activity level and CI evaluated. According to the values of CI obtained from food intake reports, the participants were divided in 3 groups: low (G1), medium (G2), high (G3) CI and were submitted to indirect calorimetry. Height, weight, body surface area (BSA), fat free mass and fat mass measured by bioimpedance were evaluated. The highest values of weight, BSA an fat mass were obtained in G1, as well as values above 1.2 for the CI:RMR ratio, which indicates a probable underestimation of CI. The highest values of physical activity and RMR were observed in the G3 (with high caloric intake). In conclusion, this paper shows that a tendency towards underestimation of self-reported caloric intake exists among obese women and that the maintenance of weight in some patients can be due to their low level of physical activity.

Objective: Describe arterial blood pressure response in adolescents undergoing exercise stress testing., Methods: This was a cross-sectional study conducted with 218 adolescents (131 of whom were males), aged between 10 to 19 years, undergoing exercise stress testing. Maximum heart rate, total exercise time, maximum oxygen uptake, systolic blood pressure (SBP) and diastolic (DBP) at rest, during maximal physical exertion and at six minutes of recovery were measured., Results: At rest, SBP values were greater in males and no difference was found in DBP between genders, although both increased with age. During exercise, SBP rose and DBP fell in both genders. SBP variation was greater in men, particularly in those over 14 years of age., Conclusion: Analysis of results showed that during physical exercise, SBP had a direct relationship with the individuals age, weight, height and body mass index, whereas DBP bore a relationship to age only.

Objectives: To compare the resting energy expenditure (REE, kcal/d) measured to the disposable equation of literature and to associate this to body composition., Methods: Twenty-eight sedentary women were volunteers [weight: 79 +/- 12 kg; stature: 164 +/- 5 cm; age: 36 +/- 11 years; body mass index (BMI, kg/m(2)): 29 +/- 4]. The body composition was estimated with anthropometry methods; REE was measured by indirect calorimetry and was estimated by the main equations of the literature. Equations were developed to estimate REE and the best of them was REE-Our., Results: The different time of harvest produced a similar result to REE measured. The Harris and Benedict, FAO/WHO/UNO only weight, and weight plus height, Schofield and REE-Our equations results were statistically similar to REE measured. The Siervo and Falconi, Schofield and Henry and Rees equations did not have correlation with the measured calorimetry. The best-isolated predictor of the REE was the body mass and the best association when adjusted to unit (kg) was lean body mass. The equation developed in the present work was: REE(kcal/d)= 21837 - 14,448 * Weight(kg) + 54,963 * Lean Mass(kg)--9,341 * Stature(cm)--4,349 * Age(years)--19753 * Body Density(g/ml)., Conclusion: The REE prediction equations can prompt to errors and seem to be population specific. The best prediction result was with the equation developed with anthropometrics variables of the volunteers (measured= 1617 +/- 237 kcal/d; REE-Our= 1616 +/- 167 kcal/d).

Objective: To compare, retrospectively, the values of maximum heart rate (MHR) and the decrease of the heart rate at the first minute of recovery, which were obtained in an exercise test (ET) performed in two different ergometers and at different moments., Methods: Sixty individuals (from 29 to 80 years old), submitted to cardiopulmonary ET in a cycle of lower limbs (CLL) in our laboratory and who had previous ET (up to 36 months) in a treadmill (TRM) in other laboratories, under identical conditions of medications of negative chronotropic action., Results: MHR was similar in CLL: 156 +/- 3 and TRM: 154 +/- 2 bpm (p=0.125), whereas dHR was higher in CLL: 33 +/- 2, EST: 26 +/- 3 bpm (mean +/- standard error of the mean) (p<0.001). In hemodynamic variables studied, the systolic blood pressure and the double product were higher in the ET-CLL (p<0.001). The electrocardiogram (ECG) was similar in both ETs, except due to more frequent supraventricular arrhythmias in CLL., Conclusion: a) With some diligence from the examiner and previous knowledge of MHR in a previous ET it is possible to obtain high levels of MHR in an ET-CLL; b) interrupting the MHR-based ET forecast through equations tends to lead to sub-maximum efforts; c) dHR differs in active and passive recoveries; d) new ways to analyze the HR behavior under exercise, which is not only the value of MHR, are necessary to characterize an ET as maximum.

This study was conducted among health care personnel (registered nurses and nurse aides) in a public hospital in São Paulo, Brazil. Work was organized in 12-hour daytime or nighttime shifts, followed by 36 hours off. The study aimed to evaluate how the nursing staff perceived the duration and quality of sleep both during and off work days, as well as their perception of alertness during working hours. There were significant differences between night and day in the duration of sleep (Student t test = 10.82; p < 0.000). Quality of daytime sleep after working night shifts was perceived as worse than nighttime sleep (Wilcoxon test, Z = 2.67; p < 0.007). Significant differences were detected in self-evaluation of alertness after the 2nd, 6th, and 10th hour of night shifts (Friedman = 63.0; p < 0.00). Alertness was perceived as worse during dawn hours. This is an indication of sleepiness at work and can have serious consequences for both health care workers and patients.

Purpose: Heart rate variability (HRV) has been studied at rest as a non-invasive tool for the assessment of cardiac autonomic control and, its attenuation is related to cardiovascular risk. However, during exercise, when important neural changes take place, HRV behaviour is not well established. The aim of this investigation was to study the heart rate (HR) and HRV responses during the different metabolic phases of maximal graded exercise in young men., Methods: Seventeen men (age 28 +/- 6 years) were submitted to a graded cardiopulmonary exercise test in a cycloergometer (30W/3 min). To study HR and HRV (standard-deviation), the electrocardiographic signal was amplified and acquired beat-to-beat in a computer at a frequency of 125 Hz (AT/Codas)., Results: The HR increases concomitantly to the increase in exercise intensity. The HRV was significantly lower than rest values after exercise intensities of 60% of peak exercise oxygen uptake, 45-60% of maximal power and, after anaerobic threshold intensity., Conclusion: This results suggest that HRV measured by standard deviation of HR decreases during exercise phases when HR increment is determined mainly due to vagal withdrawal.

Purpose: To analyse the performance of the artificial cardiac stimulation with the VVIR pacemaker whose sensor is adjusted by the variations of the autonomic nervous system in Chagas disease patients with deficiency of the conduction system., Methods: Forty-seven Chagas disease patients have been studied, 28 male between 24 and 68 years old, 36 patients had complete AV block, 8 had 2nd degree AV block and the other 3 had sinusnode disease. The patients were in class I (4), II (15), III (16) and IV (12) according to the NYHA. A 12-month-follow-up with constant clinical evaluations was carried out after pacemaker implantation. Patients were divided in 2 different groups according to the HR at rest--group 1: > 65 beats per minute (bpm) and group 2: < or = 65 bpm, for a comparative study considering: 1) HR at stress test after the implantation; 2) arterial blood pressure at rest after the implantation and, 3) evaluation of the identified electrodes such as TIR-60-UP and others., Results: The group 1 had greater HR at rest, and a smaller variation of values at stress than group 2. This shows that with this type of stimulation system it is possible to control each patient separately. The values of blood pressure at rest and during stress were not different between groups. According to the factors analysed the TIR-60-UP electrode had the same performance as the others., Conclusion: The VVIR pacemaker with the sensor adjusted by the ANS variations has provided the Chagas patients with a restoration of their physiological mechanisms. 74% of them had the improvement of either one or 2 functional classes.

The aim of this study was to assess the influence of detraining and training on the autonomic control of heart rate (HR), using time and frequency (spectral analysis) domain components of heart rate variability. Sixteen professional football players (26.7 +/- 3.8 years; 74.9 +/- 4.1 kg; 177 +/- 6.3 cm) were analysed at the end of a 1 month holiday (detraining) and after a 6 week training period (training). HR was recorded over 15 minutes with Holter equipment. The athletes rested in a supine position, in a quiet place and all test were performed between 8 and 10 AM. The subjects were requested to refrain from meals or caffeine for 12 hours before testing. In spite of the high intensity of the training period, there was no significant change in results from detraining condition to training condition. These results can have two possible explanations: (i) the high level of cardiovascular capacity in the detraining trial originated by the recreative physical activity that the players underwent during their holidays, and/or (ii) the training period was not long enough to promote any relevant effect on the autonomic control of HR.

Purpose: To study the effects of intravenous propranolol and metoprolol on cardiorespiratory and metabolic responses to exercise., Methods: Two groups of anaesthetized dogs (sodium pentobarbital, 33 mg/kg) were studied at rest and moderate exercise (induced by electrical stimulation) before and after metoprolol (0.4 mg/kg, n = 7) or propranolol (0.2 mg/kg, n = 10). Haemodynamic, metabolic and respiratory variables were measured., Results: There was a decrease in heart rate both at rest and during exercise after metoprolol and propranolol administration. The cardiac output, stroke volume and peripheral vascular resistance presented decreased responses to exercise after both drugs. O2 consumption and CO2 production were not altered significantly at rest but increased in a lesser degree during exercise. Propranolol administration reduced ventilation during rest and exercise, although the ventilatory response to exercise remained the same. Metoprolol administration did not affect ventilation at rest but reduced the ventilatory response to exercise leading to an increase of the PaCO2., Conclusion: Propranolol and metoprolol effects on cardiovascular and metabolic variables measured at rest and during exercise were the same. The ventilatory effect with metoprolol administration was different from the observed with propranolol.