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Maximal muscular vascular conductances during whole body upright exercise in humans
That muscular blood flow may reach 2.5 l kg â1 min â1 in the quadriceps muscle has led to the suggestion that muscular vascular conductance must be restrained during whole body exercise to avoid hypotension. The main aim of this study was to determine the maximal arm and leg muscle vascular cond...
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Published in: | The Journal of physiology 2004-07, Vol.558 (1), p.319-331 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | That muscular blood flow may reach 2.5 l kg â1 min â1 in the quadriceps muscle has led to the suggestion that muscular vascular conductance must be restrained during whole body
exercise to avoid hypotension. The main aim of this study was to determine the maximal arm and leg muscle vascular conductances
(VC) during leg and arm exercise, to find out if the maximal muscular vasodilatory response is restrained during maximal combined
arm and leg exercise. Six Swedish elite cross-country skiers, age (mean ± s.e.m. ) 24 ± 2 years, height 180 ± 2 cm, weight 74 ± 2 kg, and maximal oxygen uptake 5.1 ± 0.1 l min â1 participated in the study. Femoral and subclavian vein blood flows, intra-arterial blood pressure, cardiac output, as well
as blood gases in the femoral and subclavian vein, right atrium and femoral artery were determined during skiing (roller skis)
at â¼76% of and at with different techniques: diagonal stride (combined arm and leg exercise), double poling (predominantly arm exercise) and
leg skiing (predominantly leg exercise). During submaximal exercise cardiac output (26â27 l min â1 ), mean blood pressure (MAP) (â¼87 mmHg), systemic VC, systemic oxygen delivery and pulmonary (â¼4 l min â1 ) attained similar values regardless of exercise mode. The distribution of cardiac output was modified depending on the musculature
engaged in the exercise. There was a close relationship between VC and in arms ( r = 0.99, P < 0.001) and legs ( r = 0.98, P < 0.05). Peak arm VC (63.7 ± 5.6 ml min â1 mmHg â1 ) was attained during double poling, while peak leg VC was reached at maximal exercise with the diagonal technique (109.8
± 11.5 ml min â1 mmHg â1 ) when arm VC was 38.8 ± 5.7 ml min â1 mmHg â1 . If during maximal exercise arms and legs had been vasodilated to the observed maximal levels then mean arterial pressure
would have dropped at least to 75â77 mmHg in our experimental conditions. It is concluded that skeletal muscle vascular conductance
is restrained during whole body exercise in the upright position to avoid hypotension. |
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ISSN: | 0022-3751 1469-7793 1469-7793 |
DOI: | 10.1113/jphysiol.2003.059287 |