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Blood volume changes in outdoor exercise of 8‐10 hour duration
Author(s) -
Pugh L. G. C. E.
Publication year - 1969
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1969.sp008697
Subject(s) - plasma volume , blood volume , volume (thermodynamics) , dehydration , zoology , chemistry , medicine , endocrinology , anesthesia , biology , biochemistry , physics , quantum mechanics
1. Blood volume was measured with carbon monoxide on six hill‐walkers before and immediately after a 28‐mile walk on two occasions. The subjects had free access to food and fluid. 2. Blood volume increased and haematocrit fell significantly on both occasions compared with the control observations. The mean increase of blood volume was 204 ml. or 3·9% ( P < 0·01) and the mean reduction of haematocrit was 2·1% ( P < 0·02). Plasma volume calculated from these results increased by 233 ml. or 7·3%. There was no significant change in red cell volume or plasma protein concentration. 3. These changes are the opposite of those taking place in short‐term exercise and suggest that in the absence of dehydration a compensatory adjustment of blood volume takes place during exercise of many hours duration.