Abstract des Autors

Physiological responses were compared in nine stable male cardiac patients (mean+/-standard error (SE): age, 68.3+/-8.1 years; height, 172.7+/-3.9 cm; weight, 72.8+/-14.5 kg) during stationary cycling in the supine, recumbent, and upright positions. A discontinuous exercise protocol was performed in which each stage included 3 minutes of exercise and 1 minute of recovery. Each subject's workload started at 150 kgm/min and increased by 150 kgm/min per stage until volitional fatigue. Testing sessions were randomized and performed 1 week apart. Subjects continued their normal medication regimen. All subjects were participants in a community-based cardiac rehabilitation program. Dependent variables were assessed at two different intensities; submaximal (300 kgm/min) and maximal. A two-way repeated measures ANOVA found no significant differences in systolic blood pressure (SBP), diastolic blood pressure (DBP), minute ventilation (VE), respiratory exchange ratio (R), rate pressure product (RPP), and rating of perceived exertion (RPE) at submaximal (300 kgm/min) and maximal exercise efforts. Heart rate (HR) was significantly lower in the supine position compared with either the upright or recumbent positions during the submaximal workload. In addition, oxygen uptake (VO2) was significantly lower in the supine position at the submaximal workload compared with both upright and recumbent. No difference in HR or VO2 was observed at maximal exercise. Regressions of HR on VO2 showed similar slopes and intercepts for supine, recumbent, and upright ergometry. Analysis of the electrocardiogram (ECG) records suggests that more ectopy and ST segment depression were noted in the supine and recumbent positions when compared with the upright position. These ECG changes were evident in patients with preexisting myocardial ischemia during exercise. Finally, based on maximal exertional data, exercise HR prescriptions may be developed for upright ergometry when patients have been assessed in the supine or recumbent positions or vice versa. Verf.-Referat