ISSN:
1439-6327
Keywords:
Maximum cardiac output
;
Acetylene rebreathing
;
Arm ergometry
;
Gas chromatography
;
Maximum oxygen intake
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary An acetylene rebreathing technique suitable for the measurement of cardiac output in maximum exercise is described; results have a coefficient of variation of 2.9–3.6%, and show good agreement with observations made by other methods during arm and leg work. Gas samples are analysed by gas chromatograph, using silica gel and molecular sieve/glass columns. Recirculation of the foreign gas is avoided by collection of the final gas sample after 7 sec of rebreathing. Allowance is also made for other systematic errors, including the dead space of the sampling needles and solution of gas in the lung parenchyma. Arm work has a similar oxygen cost to leg work if extraneous movements are avoided; however, the maximal attainable oxygen intake is less in arm exercise (28% in 5 young men). The heart rate in sub-maximum effort is 36–39 beats/min greater for arm work; however, the maximum heart rate is unchanged. The cardiac stroke volume is 25% smaller for both sub-maximum and maximum arm work, while the arterio-venous oxygen difference is slightly greater than in leg work. Both stroke volume and arterio-venous difference increase somewhat between 60 and 100% of aerobic power, but the main burden of increasing oxygen transport is accepted by the increase in heart rate.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00698024
