Exercise capacity is reduced in pulmonary arterial hypertension and in chronic left heart failure, but it is not known whether the cardiopulmonary exercise testing profile is different in the two conditions at the same severity of functional limitation.Nineteen patients with pulmonary arterial hypertension and 19 with chronic heart failure underwent a 6-min walk test and symptom-limited maximal incremental cycle ergometry.The patients with pulmonary arterial hypertension and chronic heart failure did not differ in New York Heart Association Functional Class (mean¡SEM 2.8¡0.1 versus 2.8¡0.2), 6-min walking distance (395¡30 versus 419¡20 m), peak work-rate, oxygen consumption, ventilation and cardiac frequency. However, patients with pulmonary arterial hypertension exhibited higher dyspnoea scores (5.8¡0.6 versus 3.8¡0.5) higher ventilatory equivalents for carbon dioxide (58¡3 versus 44¡3 at the anaerobic threshold) and lower peak oxygen pulse (5.9¡0.4 versus 8.7¡0.5 mL?beat -1 , or 53¡4 versus 64¡4% of the predicted value).It is concluded that the cardiopulmonary exercise testing profile in pulmonary arterial hypertension differs from that in chronic heart failure by showing more dyspnoea at comparable work-rates, related to greater reductions in ventilatory efficiency and stroke volume.
Cerebral blood flow has been reported to increase during dynamic exercise, but whether this occurs in proportion to the intensity remains unsettled. We measured middle cerebral artery blood flow velocity (vm) by transcranial Doppler ultrasound in 14 healthy young adults, at rest and during dynamic exercise performed on a cycle ergometer at a intensity progressively increasing, by 50 W every 4 min until exhaustion. Arterial blood pressure, heart rate, end-tidal, partial pressure of carbon dioxide (PETCO2), oxygen uptake (VO2) and carbon dioxide output were determined at exercise intensity. Mean vM increased from 53 (SEM 2) cm.s-1 at rest to a maximum of 75 (SEM 4) cm.s-1 at 57% of the maximal attained VO2 (VO2max), and thereafter progressively decreased to 59 (SEM 4) cm.s-1 at VO2max. The respiratory exchange ratio (R) was 0.97 (SEM 0.01) at 57% of VO2max and 1.10 (SEM 0.01) at VO2max. The PETCO2 increased from 5.9 (SEM 0.2) kPa at rest to 7.4 (SEM 0.2) kPa at 57% of VO2max, and thereafter decreased to 5.9 (SEM 0.2) kPa at VO2max. Mean arterial pressure increased from 98 (SEM 1) mmHg (13.1 kPa) at rest to 116 (SEM 1) mmHg (15.5 kPa) at 90% of VO2max, and decreased slightly to 108 (SEM 1) mmHg (14.4 kPa) at VO2max. In all the subjects, the maximal value of vm was recorded at the highest attained exercise intensity below the anaerobic threshold (defined by R greater than 1). We concluded that cerebral blood flow as evaluated by middle cerebral artery flow velocity increased during dynamic exercise as a function of exercise intensity below the anaerobic threshold.(ABSTRACT TRUNCATED AT 250 WORDS)
These results suggest that decreased aerobic exercise capacity after intake of beta-blockers is accompanied by decreased ventilation at any metabolic rate. However, this occurs without detectable change in the sympathetic nervous system tone or in metabo- or chemosensitivity and is therefore probably of hemodynamic origin.
The SBP and HR responses to resistance training are related to the duration of exercise. Sets with < or =10 repetitions of high intensity should be preferred to longer sets with low intensity. Pauses between exercise sets should exceed 1 min. Blood pressure should be measured during the last repetitions of the exercise set.
The SBP and HR responses to resistance training are related to the duration of exercise. Sets with < or =10 repetitions of high intensity should be preferred to longer sets with low intensity. Pauses between exercise sets should exceed 1 min. Blood pressure should be measured during the last repetitions of the exercise set.
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