hen a subject performs incremental exercising testing, exercise hyperpnea increases toward the end of the exercise. This is due to an increase in acidosis, which is caused by accumulating lactic acid. 1 Lactic acid is produced once the working skeletal muscle cells reach the anaerobic threshold (AT). 2 Usually circulating bicarbonate compensates for this lactic acidosis to begin with. This period is called the isocapnic buffering stage. 3 However, beyond a certain point work intensity becomes so great that lactic acid production can no longer be compensated by circulating bicarbonate and hyperventilation begins. This point is called the respiratory compensation point (RCP). 2 We have previously reported that in heart failure the ability of skeletal muscle to uilize oxygen is increased during mild exercise by increasing the arteriovenous oxygen difference. 4 However, there are few reports of aerobic metabolism after AT. The time from AT to the RCP (RCP-AT time), ie, the duration of isocapnic buffering, varies from subject to subject, although the normal value is believed to be approximately 2 min. 3,5 RCP-AT time depends on the rate of aerobic and anaerobic metabolism after AT, and for subjects with reduced exercise tolerance, such as chronic heart failure patients, this period seems to be shorter. However, the significance of this period is not yet fully understood, and it has not been determined whether the duration of this period is correlated with any indicators of exercise tolerance, such as the anaerobic threshold.Thus, we studied the correlation between the RCP-AT time and the anaerobic threshold and also investigated the correlation between RCP-AT time and the ∆V • O2/∆WR, which is thought to indicate the peripheral blood flow and also the aerobic exercise tolerance. We hypothesized that RCP-AT time may be a new indicator that shows the rate of aerobic and anaerobic metabolism after the AT point. Methods Study PatientsWe studied 37 patients with chronic heart failure (19 men and 18 women); all patients were in New York Heart Association functional class II or III. Their diagnoses were dilated cardiomyopathy and coronary artery disease, and their mean age was 57.8±6.3 years. The nature and the purpose of the study and the risks involved were explained, and informed consent was obtained from each subject before his or her voluntary consent to entry into the study. Ventilatory ParametersPatients performed the cardiopulmonary exercise test under expired gas analysis. Expired gases were monitored continuously in all patients by a breath-by-breath expired gas analyzer (AE280S, Minato Ikagaku, Tokyo, Japan). Oxygen uptake (V • O2), carbon dioxide output (V • CO2), and minute ventilation (V • E) were measured. Anaerobic threshold (AT) was determined as the break point in the V-slope method. 1 The respiratory compensation point (RCP) was determined as the point at which the ratio of minute ventiJpn Circ J 1999; 63: 274 -277 (Received August 5, 1998; revised manuscript received December 24, 1998; accepted December...

Blood viscosity (etaB) is low in athletes, but the effect of exercise training on etaB during endurance exercise at an anaerobic threshold (AT) intensity in non-athletes is not well known, although it is known that exercise training sometimes induces the hyperviscosity syndrome. Fourteen subjects were recruited and divided into 2 groups: those who trained at an AT intensity for 30 min/day, 3 times weekly for 1 year (Group T, n=8), and sedentary subjects (Group C, n=6). The test protocol consisted of a single 30-min treadmill exercise at each individual's AT intensity, which was determined in advance. The etaB, plasma viscosity (etaP), and hematocrit were measured just before and at the end of the treadmill exercise. The subjects were not allowed to drink any water before exercise. In the Group C subjects, the hematocrit and etaP increased significantly and the etaB tended to increase. However, in the Group T subjects, the hematocrit and etaP did not increase and the etaB decreased significantly. These data indicate that long-term exercise training attenuates the increase in blood viscosity during exercise.

No abstract

No abstract

No abstract

No abstract

Key words：chronic hemodialysis, percutaneous coronary intervention, cardiac rehabilitation, anaerobic threshold, cardiopulmonary exercise test 〈Abstract〉 We evaluated three chronic hemodialysis patients who were treated with percutaneous coronary intervention （PCI）or coronary surgery in a 3-month exercise-based cardiopulmonary rehabilitation program. A 57-year-old and a 58-year-old female underwent PCI, and a 63-year-old-male received a coronary bypass graft（CABG). Cardiopulmonary exercise testing（CPX）was performed using breath-by-breath gas sampling on two occasions： before and 3 months after rehabilitation. The anaerobic threshold（AT), exercise time, oxygen uptake（VO2), Barthel index, and vitality index were measured. The AT, exercise time, peak VO2, and vitality index increased in 3 patients. The Barthel index did not change from the baseline. Cardiovascular exercise with CPX should be considered in chronic hemodialysis patients undergoing coronary intervention. Further research is needed to develop appropriate methods for cardiovascular rehabilitation and evaluate the long-term effects of cardiovascular exercise on the aerobic capacity, physical functioning, and quality of life.