Effect of central hypervolemia on cardiac performance during exercise

Sheldahl, L.M.; Wann, L.S.; Clifford, P.S.; Tristani, F.E.; Wolf, L.G.; Kalbfleisch, J.H.

Journal of Applied Physiology Respiratory Environmental and Exercise Physiology 57(6): 1662-1667

1984


ISSN/ISBN: 0161-7567
PMID: 6511540
DOI: 10.1152/jappl.1984.57.6.1662
Accession: 005225799

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Abstract
To investigate the effect of different levels of central blood volume on cardiac performance during exercise, M-mode echocardiography was utilized to determine left ventricular size and performance during cycling exercise in the upright posture (UP), supine posture (SP) and head-out water immersion (WI) . At submaximal work loads requiring a mean O2 consumption (.ovrhdot.VO2) of 1.2 l/min and 1.5 l/min, mean left ventricular end-diastolic and end-systolic dimensions were significantly greater (P < 0.05) with WI than UP. In the SP during exercise, left ventricular dimensions were intermediate between UP and WI. Heart rate did not differ significantly among the 3 conditions at rest and at submaximal exercise up to a mean .ovrhdot.VO2 of 1.8 l/min. At a mean .ovrhdot.VO2 of 2.4 l/min, heart rate in the UP was significantly greater than WI (P < 0.01) and the SP (P < 0.05). Maximal .ovrhdot.VO2 did not differ statistically in the 3 conditions. These data indicate that a change in central blood volume results in alterations in left ventricular end-diastolic and end-systolic dimensions during moderate levels of exercise and a change in heart rate at heavy levels of exercise.