Abstract

The purpose of this study was to determine postural effects on upper and lower limb peripheral resistance (PR) after submaximal exercise. Twelve subjects (6 men, 6 women) completed submaximal cycle ergometer tests (60 age-predicted maximum heart rate) in the supine and upright seated positions. Each test included 20 min. of rest, 20 min. of cycling, and 15 min. of recovery. Stroke volume and heart rate were determined by impedance cardiography, and blood pressure was measured by auscultation during rest, immediately after exercise, and at min. 1-5, 7.5, 10, 12.5, and 15 of recovery. Peripheral resistance was calculated from values of mean arterial pressure and cardiac output. No significant postural differences in PR were noted during rest for either limb. Immediately after exercise, PR decreased (55 to 61) from resting levels in both limbs, independent of posture. Recovery ankle PR values were significantly different between posture. Upright ankle PR returned to 92 of the resting level within four minutes of recovery, compared to 76 of the resting level after 15 min. in the supine posture. Peripheral resistance values in the supine and upright arm were not affected by posture and demonstrated a gradual pattern of recovery similar to the supine ankle recovery response (85 to 88 of rest within 15 min.). The accelerated recovery rate of PR after upright exercise may result from local vasoconstriction mediated by a central regulatory response to stimulation from gravitational pressure on lower body circulation. Verf.-Referat