Heat and exercise. Effects on blood volume

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Bibliographische Detailangaben
Deutscher übersetzter Titel:Hitze und koerperliches Training. Die Auswirkungen auf das Blutvolumen
Autor:Harrison, Michael H.
Erschienen in:Sports medicine
Veröffentlicht:3 (1986), 3, S. 214-223, Lit.
Format: Literatur (SPOLIT)
Publikationstyp: Zeitschriftenartikel
Medienart: Gedruckte Ressource Elektronische Ressource (online)
Sprache:Englisch
ISSN:0112-1642, 1179-2035
DOI:10.2165/00007256-198603030-00005
Schlagworte:
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Erfassungsnummer:PU198706030445
Quelle:BISp

Abstract

The ability of the cardiovascular system to meet the competing demands of skin and muscle for blood flow without compromising regulation of blood pressure is a critical factor influencing the capacity for prolonged work in hot environments. Unfortunately, this competition is exacerbated by the progressive reduction in blood volume (haemoconcentration) which can occur during exercise int he heat. Thermal stress alone induces haemoconcentration only above the upper limit of the prescriptive zone. Exercise performed in a supine or seated position is associated with an initial rapid haemoconcentration, which, if the environmental temperature is high, is followed by a slower, secondary haemoconcentration. Exercise performed in a standing position is associated with variable changes in blood volume, and effects of a superimposed thermal stress are small unless dehydration supervenes. The magnitude of exercise-induced primary haemoconcentration is limited, probably by oedema-preventing mechanisms, and is inversely related to the magnitude of any preceding postural haemoconcentration. Dehydration reduces absolute blood volume (induces hypovalaemia), and accentuates exercise haemoconcentration. Heat acclimatisation attenuates dehydration by inducing hypervolaemia, but still appears to accentuate exercise haemoconcentration. During exercise in the heat haemoconcentration represents an undesirable response, the effects of which can be mitigated by heat acclimatisation, endurance training, and preventing dehydration. Verf.-Referat