Impact of acute exposure to air pollution on the cardiorespiratory performance of military firemen.

The objective of the present study was to determine the impact of acute short-term exposure to air pollution on the cardiorespiratory performance of military firemen living and working in the city of Guarujá, São Paulo, Brazil. Twenty-five healthy non-smoking firemen aged 24 to 45 years had about 1 h of exposure to low and high levels of air pollution. The tests consisted of two phases: phase A, in Bertioga, a town with low levels of air pollution, and phase B, in Cubatão, a polluted town, with a 7-day interval between phases. The volunteers remained in the cities (Bertioga/Cubatão) only for the time required to perform the tests. Cumulative load 10 +/- 2 min-long exertion tests were performed on a treadmill, consisting of a 2-min stage at a load of 7 km/h, followed by increasing exertion of 1 km h-1 min-1 until the maximum individual limit. There were statistically significant differences (P < 0.05) in anaerobic threshold (AT) between Cubatão (35.04 +/- 4.91 mL kg-1 min-1) and Bertioga (36.98 +/- 5.62 mL kg-1 min-1; P = 0.01), in the heart rate at AT (AT HR; Cubatão 152.08 +/- 14.86 bpm, Bertioga 157.44 +/- 13.64 bpm; P = 0.001), and in percent maximal oxygen consumption at AT (AT%VO2max; Cubatão 64.56 +/- 6.55%, Bertioga 67.40 +/- 5.35%; P = 0.03). However, there were no differences in VO2max, maximal heart rate or velocity at AT (ATvel) observed in firemen between towns. The acute exposure to pollutants in Cubatão, SP, caused a significant reduction in the performance at submaximal levels of physical exertion.

Impact of acute exposure to air pollution on the cardiorespiratory performance of military firemen

The objective of the present study was to determine the impact of acute short-term exposure to air pollution on the cardiorespiratory performance of military fireman living and working in the city of Guarujá, São Paulo, Brazil. Twenty-five healthy non-smoking firemen aged 24 to 45 years had about 1 h of exposure to low and high levels of air pollution. The tests consisted of two phases: phase A, in Bertioga, a town with low levels of air pollution, and phase B, in Cubatão, a polluted town, with a 7-day interval between phases. The volunteers remained in the cities (Bertioga/Cubatão) only for the time required to perform the tests. Cumulative load 10 ± 2 min-long exertion tests were performed on a treadmill, consisting of a 2-min stage at a load of 7 km/h, followed by increasing exertion of 1 km h-1 min-1 until the maximum individual limit. There were statistically significant differences (P < 0.05) in anaerobic threshold (AT) between Cubatão (35.04 ± 4.91 mL kg-1 min-1) and Bertioga (36.98 ± 5.62 mL kg-1 min-1; P = 0.01), in the heart rate at AT (AT HR; Cubatão 152.08 ± 14.86 bpm, Bertioga 157.44 ± 13.64 bpm; P = 0.001), and in percent maximal oxygen consumption at AT (AT percentVO2max; Cubatão 64.56 ± 6.55 percent, Bertioga 67.40 ± 5.35 percent; P = 0.03). However, there were no differences in VO2max, maximal heart rate or velocity at AT (ATvel) observed in firemen between towns. The acute exposure to pollutants in Cubatão, SP, caused a significant reduction in the performance at submaximal levels of physical exertion.

[Early and late physiological effects of balloon mitral valvuloplasty]. / Adaptações fisiológicas precoces e tardias após valvotomia mitral por cateter balão.

PURPOSE: To evaluate the early and late cardiorespiratory responses after balloon mitral valvuloplasty. METHODS: Nine female patients aged 35 +/- 9 years with mitral stenosis, in class II or III (NYHA) underwent up-right ergoespirometric test, resting electrocardiogram and echocardiogram before, 3 to 5 days (early evaluation) and 8 to 12 months (late evaluation) after mitral valvuloplasty. All patients were treated with digitalis and diuretics. RESULTS: During late evaluation, 44% patients were in class II and 56% were in class I (NYHA). The resting heart rate decreased (87 +/- 11 bpm vs 85 +/- 7 bpm vs 75 +/- 9 bpm) and the number of steps increased (4 +/- 1 steps vs 5 +/- 2 steps vs 6 +/- 1 steps); the peak oxygen uptake improved only in the late evaluation (16 +/- 3 mL/kg/min vs 18 +/- 4 mL/kg/min vs 22 +/- 7 mL/kg/min). The anaerobic threshold, minute ventilation (VE) and ventilatory equivalent for oxygen showed no change. The heart rate (1st step: 124 +/- 18 bpm vs 112 +/- 13 bpm vs 87 +/- 15 bpm), O2 uptake (1st step: 10 +/- 2 mL/ kg/min vs 8 +/- 2 mL/kg/min vs 8 +/- 2 mL/kg/min) and VE decreased during submaximal exercise in early and late phases. The mitral valve area decreased in the late evaluation (0.94 cm2 vs 1.66 cm2 vs 1.20 cm2). CONCLUSION: Although partial restenosis tended to occur in these patients, they improved the functional class and cardiorespiratory performance and cardiocirculatory load during submaximal exercise.

[Cardiorespiratory response during exercise in heart transplant recipients. Comparative ergoespirometric analysis with normal health subjects]. / Respostas cardiorrespiratórias durante exercício em portadores de transplante cardíaco. Análise ergoespirométrica comparativa com indivíduos normais.

PURPOSE: To evaluate the cardiorespiratory response of heart transplant (HT) recipients. METHODS: Nine HT recipients (GI) underwent ergospirometric tests and were compared to 9 apparently healthy, sedentary subjects with similar sex, age, weight and height (GII). All were male patients aging 48 +/- 12 years, in functional class I (NYHA) an average of 23 +/- 21 months after HT. They were receiving cyclosporin, azathioprine, prednisone, dipyridamole and antihypertensive drugs. The tests were symptom-limited and they were interrupted due to exhaustion. RESULTS: During peak exercise, GI had a significantly lower physical performance related to lower VO2, VE, VEO2, HR, endurance time and work load. At the anaerobic threshold, VO2, endurance time and work load levels were also significantly lower in GI. The physical performance was similar between the groups in the 40W load. CONCLUSION: The cardiorespiratory performance in GI was significantly lower at peak exercise and similar to GII in the 40W load, showing the HT benefits cardiac patients during usual activities.

Adaptaçöes fisiológicas precoces e tardias após valvotomia mitral por cateter baläo / Early and late physiological effects of balloon mitral valvuloplasty

OBJETIVO - avaliaçäo näo invasiva das respostas cardiopulmonares ao exercício a curto e longo prazo após valvotomia por cateter baläo. MÉTODOS - Estudaram-se 9 pacientes do sexo feminino, 35ñ9 anos, com estenose mitral, tipo funcional II ou III, em uso de digitálicos e diuréticos, através de teste ergoespirométrico, eletrocardiograma e ecocardiograma, antes e após valvotomia em fase precoce (3 a 5 dias) e tardia (8 a 12 meses). RESULTADOS - Os pacientes evoluíram para tipo funcional II (44 por cento) ou I (56 por cento), na fase tardia. Houve reduçÝo da freqüência cardíaca de repouso (87ñ11bpm vs 85ñ7bpm vs 75ñ9bpm) e elevaçäo do número de estágios (4ñ1 estágios vs 5ñ2 estágios vs 6ñ1 estágios); a capacidade aeróbica máxima aumentou apenas na fase tardia (16ñ3mL/kg/min vs 18ñ4mL/kg/min vs 22ñ7mL/kg/min). O limiar anaeróbico, a ventilaçäo pulmonar e o equivalente ventilatório do O2 (Oxigênio 2) permaneceram inalterados. Nas cargas submáximas de exercício ocorreu reduçäo da freqüência cardíaca (estágio I: 124ñ18bpm vs 112ñ13bpm vs 87ñ15bpm), consumo de O2 (Oxigênio 2) (estágio I: 10ñ2mL/kg/min vs 8ñ2mL/kg/min vs 8ñmL/kg/min) e ventilaçäo pulmonar, nas fases precoce e tardia. A área valvar mitral mostrou reduçöes na fase tardia (0,94cm² vs 1,66cm² vs 1,20cm²). CONCLUSÄO - Apesar da tendência à reestenose parcial, houve melhora no tipo funcional e no desempenho cardiopulmonar com diminuiçäo da sobrecarga circulatória no exercício submáximo.

Fisiologia do exercício aplicada ao sistema cardiovascular / Exercise physiology applied to the cardiovascular system

As adaptiaçöes do sistema cardiovascular durante o exercício säo caracterizadas por meio de mecanismos de regulaçäo e de índices de limitaçäo funcional. O processo de regulaçäo da funçäo cardiovascular no exercício é um mecanismo de ajuste do sistema de transporte de oxigênio à demanda metabólica. Um sistema regulador preciso aumenta o débito cardíaco a partir de informaçöes aferentes de origem central e periférica, no sentido de proprocionar ao músculo esquelético aoporte de oxigênio adequado às nessidades energéticas. O aumento do débito cardíaco é consequente ao incremento da frequência cardíaca por reduçäo do tônus vagal e aumento da descarga simpática, como também ao aumento do volume de ejeçäo sistólico, principalmente por aumento do enchimento diastólico. O principal índice de limitaçäo indicador da capacidade funcional do sistema cardiovascular é o consumo máximo de oxigênio (Vo2max). A captaçäo máxima de oxigênio é funçäo do débito cardíaco máximo e da extraçäo máxixa de oxigênio periférc. O VO2 max, que é, portanto, o principal indicador da capacidade funcional, pode ser limitado por fatores "centrais" diretamente relacionados ao ajuste do débito cardíaco, como a mecanismos de limitaçäo "periférica" decorrentes da regressäo das características morfológicas e funcionais do músculo esquelético.

The influence of isotonic exercise on cardiac hypertrophy in arterial hypertension: impact on cardiac function and on the capacity for aerobic work.

Intense physical training through isotonic exercises has controversial effects in individuals with moderate to severe hypertension. In this study, normotensive Wistar rats and rats with renovascular hypertension (Goldblatt II) were subjected to intense physical exercise involving two 50-min swimming sessions per day for a period of 12 weeks. At the end of the study, we evaluated the effect of training on arterial pressure, the capacity for aerobic work and cardiac function. Our results demonstrate that intense physical training has no effect on the arterial blood pressure of normotensive rats or of animals with moderate renovascular hypertension. Hypertensive animals with cardiac hypertrophy require a greater period of training in order to attain the same capacity for aerobic work as normotensive rats. This difference may result from an inability of the former animals to increase cardiac compliance, thereby impeding more extensive usage of the Frank-Starling mechanism to subsequently increase the systolic cardiac performance. Cardiac hypertrophy induced by exercise did not summate with that induced by arterial hypertension. Physical exercise normalized the end-diastolic left ventricular pressure in hypertensive animals without any corresponding increase in the compliance of the chamber. The first derivative of left ventricular pulse pressure (+/- dP/dt) was greater in the hypertensive trained group than in the hypertensive sedentary rats. These observations suggest that a systolic dysfunction of the left ventricle involving an elevated residual volume secondary to arterial hypertension may be corrected by physical exercise such as swimming.

[Effect of propranolol and metoprolol on cardiorespiratory and metabolic response to exercise]. / Efeito do propranolol e metoprolol nas respostas cárdio-respiratórias e metabólicas ao exercício.

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.

Effect of exercise during pregnancy, graded as a percentage of aerobic capacity: maternal and fetal responses of the rat.

1. A number of variables were studied in pregnant rats that underwent strenuous exercise during pregnancy. They were: total weight gain, daily weight gain, length of pregnancy, number of offspring. Also the weight, the heart weight and fibre/capillary ratio of the newborn male rats and their VO2 max at 90 days were measured. 2. The exercise was graded in accordance to previous aerobic capacity as determined by VO2 max with relative loads of 60% (E60), 70% (E70), 80% (E80) and 90% (E90) of VO2 max being applied to the various groups (N = 6 per group). 3. The total weight gain and daily weight gain was significantly less in the E70, E80 and E90 groups. Weight gain in the anabolic phase (0-14d) was not different, but during the first week the weight gain in the E90 group was significantly less than control group. In the catabolic phase the observations were similar the first week of the anabolic phase. 4. Length of pregnancy, heart weight offspring and VO2 max of 90-day-old male rats were not significantly different. The number of offspring of the E90 group was significantly smaller than the control, E60 and E70 groups. 5. The offspring body weight was less in the E70, E80 and E90 groups than control group and was significantly less in the E90 group compared to the E60 and E70 groups. 6. The fibre/capillary ratio of the offspring was different in the E90 group compared to the control group. 7. These results suggest that the effect of exercise depends on the relative work load applied to the mother and these effects are particularly marked at high work loads.

Effect of exercise training during pregnancy: maternal and fetal responses of the rat

Pregnancy duration, offspring number, body weight gain per day, as well as offspring body and heart weights were studied in pregnant Wistar rats subjected to exercise training at relative work loads of 60, 70, 80 or 90% of maximum oxygen consumption (VO2max) (N = 6 for each group). Pregnancy duration, offspring number and heart weight of the rats subjected to exercise during pregnancy were not different from the control group not subjected to exercise training. Body weight gain per day of pregnant rats subjected to exercise was 4.64 + or - 0.21, 4.79 + or - 0.12 g, respectively, for work loads of 70,80 or 90% of VO2max. This decrease of body weight gain per day was ignificantly different (P<0.05) from the control group (5.69 + or - 0.22 g). The offspring body weight decreased in the rats submitted to work loads of 70,80 and 90% of VO2max(5.3-0 + or - 0.02 and 5.24 + or - 0.01g, respectively) by comparison to the control group value (5.73 + or - 0.07 g). These results suggest that only intense exercise could impair body weight gain in pregnant rats and their offspring

Oxygen consumption and ventilation during constant-load exercise in runners and cyclists.

The effect of using specialized or no specialized muscle groups on ventilatory threshold (VT) and on maintenance of steady-state oxygen consumption during long term exercise on treadmill and on cycle ergometer was studied in ten endurance runners and nine cyclists. Initially, maximum oxygen consumption (VO2max) and VT were determined. Oxygen consumption (VO2) ventilation (VE) respiratory rate (f), and blood lactate (in the beginning and at the end of exercise) were measured during exercise at constant relative loads of 60, 70, and 80% of VO2max. In the runners, both VO2max and VT (expressed as % VO2max and VO2 l/min) were greater on treadmill than on cycle ergometer and in the cyclists, VO2max was higher on cycle ergometer than on treadmill, but no differences in VT were detected between the two tests. The VO2, VE, and f drifts correlated with blood lactate level as well as with the calculated VT. The results suggest that the effect of using specialized or no specialized muscle groups on the maintenance of VO2 steadiness is achieved through training-induced changes on the level of blood lactate and, in VT.

Effect of exercise training during pregnancy: maternal and fetal responses of the rat.

Pregnancy duration, offspring number, body weight gain per day, as well as offspring body and heart weights were studied in pregnant Wistar rats subjected to exercise training at relative work loads of 60, 70, 80 or 90% of maximum oxygen consumption (VO2max) (N = 6 for each group). Pregnancy duration, offspring number and heart weight of the rats subjected to exercise during pregnancy were not different from the control group not subjected to exercise training. Body weight gain per day of pregnant rats subjected to exercise was 4.64 +/- 0.21, 4.79 +/- 0.22 and 4.72 +/- 0.12 g, respectively, for work loads of 70, 80 or 90% of VO2max. This decrease of body weight gain per day was significantly different (P less than 0.05) from the control group (5.69 +/- 0.22 g). The offspring body weight decreased in the rats submitted to work loads of 70, 80 and 90% of VO2max (5.30 +/- 0.05, 5.34 +/- 0.02 and 5.24 +/- 0.01 g, respectively) by comparison to the control group value (5.73 +/- 0.07 g). These results suggest that only intense exercise could impair body weight gain in pregnant rats and their offspring.