Treinamento físico e frequência cardíaca em ratos idosos: avaliação da frequência cardíaca intrínseca e da modulação autonômica, do repouso ao exercício de intensidade progressiva escalonada / Exercise training and heart rats in old rats: intrinsic heart rate and autonomic modulation assessment from rest to progressive intensity exercise

Estudou-se o efeito do treinamento físico sobre: a freqüência cardíaca (FC), a freqüência cardíaca intrínseca (FCI) o efeito vagal (EV), o efeito simpático (ES), o tônus vagal (TV) e o tônus simpático (TS) de ratos idosos em repouso, na esteira, e ao exercício, de intensidade progressiva (4 estágios de 5 min. a 5, 7,5, 10 e 15 m.min-1). Foram utilizados 20 ratos Wistar machos, divididos em dois grupos: treinado (T, 28+2 meses, 460+36 g), submetido a 10 semanas de treinamento físico de moderada intensidade e sedentário (S, 28+2 meses, 461+43 g), apenas manipulados durante este período. Verificou-se a resposta da FC a doses crescentes de agonistas adrenérgico (isoproterenol) e muscarínico (metacolina). T apresentou FC de repouso e ao exercício de intensidade progressiva menor do que o grupo S, o mesmo acontecendo com a FCI. Não houve diferença na atividade vagal ou na influência simpática em nenhuma das condições estudadas. Tanto a FC, quanto a FCI aumentaram do repouso para o exercício e com o aumento da intensidade. A atividade vagal diminuiu e a atividade simpática aumento do repouso para o exercício e com o aumento da intensidade / This investigation was undertaken in order to study intrinsic heart rate and autonomic contributions to heart rate during an acute bout of exercise on 10 sedentary (S) and 10 trained (T) old rats (28+2 months old). Exercise training was performed 5 times a week for 10 weeks on a motor treadmill at 12 m.min-1 for 60 min since the fourth week. heart rate was recorded at rest on the treadmill and during exercise at 5, 7.5, 10 and 15 m.min-1, for 5 min per stage. Intrinsic heart rate as well as vagal and sympathetic effects were studied after the administration of methylatropine (3mg.kg-1) and propranolol (7 mg.kg-1). Exercise training reduced heart rate and intrinsic heart rate both at rest and during exercise. There was no change in either vagal or sympathetic contribution to heart rate at rest or exercise. We concluded that in old rats heart rate at rest and during exercise of light, moderate and high intensity is reduced due to a decrease in intrinsic heart rate. As exercise intensity increases vagal contributions to heart rate become less important while sympathetic contributions become more evident...

Efeito do treinamento físico de nataçäo sobre o sistema cardiovascular de ratos normotensos / Effect of swimming training on the cardiovascular system in normotensive rats

Uma das principais adaptaçöes ao treinamento físico (TF) aeróbio é a bradicardia de repouso, observada tanto em humanos (Goldsmith, Bigger, Steinman & Fleiss, 1992, 1992; Kenney, 1985; Puig, Freitas, Carvalho, Puga, Ramos, Fernandes, Costa & Freitas, 1993; Katona, McLean, Dighton & Guz, 1982) como em animais de experimentaçäo (Bolter, Hughson & Critz, 1973; Negräo, Moreira, Santos, Farah & Krieger, 1992; Brum, 1995; Kalil, 1997). No entanto, a evoluçäo da frequência cardíaca (FC) e da pressäo arterial (PA) durante o período de TF e o curso temporal para que a bradicardia de repouso ocorra ainda näo estäo totalmente esclarecidos. Foram estudados 16 ratos Wistar machos. Oito foram treinados (T) durante 8 semanas, utilizando um protocolo de nataçäo de baixa intensidade e oito foram mantidos sedentários (S). A PA sistólica e a FC foram registradas batimento-a-batimento, duas vezes por semana durante o período de TF através de um esfigmomanômetro de cauda...

Dissociação clínico-morfológica em portadores de estenose mitral / Clinico-morphological dissociation in patients with mitral valve stenosis

PURPOSE--To study characteristics of the natural history of mitral stenosis (MS) in patients that have no correlation between mitral valve areas (MVA) and symptoms. METHODS--We studied 18 patients with MS, that presented no correlation between MVA and functional class (FC), 16 (89) were female and two (11) men, with age ranging from 16 to 54 (mean 33) years. Patients assigned to group A (8 cases) had FC III and MVA > or = 1.5 cm2 and group B (10 cases) FC I/II and MVA < 1.1 cm2. FC and MVA at the start (initial time-It) and after 12 months or before surgical correction (SC) or percutaneous mitral balloon valvuloplasty (PBV) (final time-Ft) were compared. All patients with predict O2 uptake (PRED VO2) at It were evaluated. RESULTS--Five (63) patients of group A, that maintained MVA > or = 1.5 cm2, changed to FC I/II but three (38) needed a SC or PBV (2 with lesser MVA at Ft). At group B, six (60) patients needed SC or PBV. CONCLUSION--MS patients with MVA > or = 1.5 and FC III, providing MVA do not decrease, improves their FC, becoming it more compatible with MVA PRED VO2. The cases of group B presented the greatest probability of needing SC or PVB.

Avaliação cardiorrespiratória ao exercício no idoso sadio / Cardiopulmonary Exercise Test in the Evalution of Healthy Elderly Men

PURPOSE--To study methodological aspects and results of cardiopulmonary exercise tests in elderly. METHODS--Twenty-five men (mean age 65 +/- 5 years) performed a cardiopulmonary exercise test using a bicycle ergometer and a progressive continuous work load increase protocol was employed. A computadorized system (2001 CAD/Net System-MGC), which includes a gas analyser and a pneumotacograph, was used for on line monitoring of oxygen and carbon dioxide expired fraction and also of pulmonary flow. RESULTS--We observed the following values of oxygen uptake, pulmonary ventilation and respiratory gas exchange: rest=4 +/- 1 ml/kg-1/min-1, 11 +/- 2 l/min-1 and 0.80 +/- 0,1, respectively: anaerobic threshold=12 +/- 3 ml/kg-1/min-1, 29 +/- 6 l/min-1 and 0.90 +/- 0.1, respectively: respiratory compensation point=18 +/- 4ml/kg-1/min-1, 47 +/- 1 l/min-1 and 1.07 +/- 0.1, respectively, and peak of exercise = 13 +/- 5 ml/kg-1/min-1, 76 +/- 18 l/min-1 and 1.21 +/- 0.2, respectively. The anaerobic threshold and the respiratory compensation point were achieved at 53 +/- 11 and 77 +/- 9//of peak oxygen uptake respectively. The elderly shown slightly increased values of the relation volume dead/tidal volume at rest with a slightly smaller decrease of its values during exercise in comparison to data obtained from young healthy untrained subjects. The heart rate prescription for exercise based on the heart rate reserve was higher than that based on the cardiorespiratory and metabolic responses (113-126bpm vs 96-114bpm). CONCLUSION--The cardiorespiratory and metabolic responses pattern in the elderly is quite heterogeneous. The heart rate prescription for exercise based on conventional stress tests seems to overestimate cardiorespiratory and metabolic capacity in healthy elderly men. The determination of anaerobic threshold and respiratory compensation point from cardiopulmonary exercise test data optimize exercise prescription for healthy elderly men

Atividade física para o idoso: características, benefícios e modalidades / Physical activity for the elderly: characteristics, benefits and modalities

A atividade física pode atenuar a reduçäo da capacidade funcional, os fatores de risco de doenças cardiovasculares, os distúrbios do aparelho locomotor e até mesmo a depressäo e ansiedade que acompanham o sedentarismo e a senescência. As avaliaçöes cardiorespiratória, metabólca e biomecânica permitem determinaçäo objetiva da capacidade física e orientam a prescriçäo do exercício. A elaboraçäo de programa de treinamento físico deve ser individualizada e considerar, além das características do exercício, a capacidade física e a condiçäo clínica do geronte