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Int J Sports Med 1982; 03(4): 230-233
DOI: 10.1055/s-2008-1026093
© Georg Thieme Verlag Stuttgart · New York

Hemoglobin, Hematocrit, and Calculated Plasma Volume Changes Induced by a Short, Supramaximal Task

A. Rotstein, O. Bar-Or, R. Dlin
  • Department of Research and Sports Medicine Wingate Institute for Physical Education and Sports, Netanya, Israel 42902
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Publication Date:
14 March 2008 (online)

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Abstract

The influence of a short, supramaximal task of 30 s duration on plasma volume (PV) was tested in 14 female physical education students. Hemoglobin (Hb), hematocrit (Hct), and osmolality (Osm) were tested pre- and post-exercise. Performance of the exercise test, consisting of 30 s all-out pedaling against a load of 4.4 J/kg body weight per pedal revolution, brought about a significant elevation in the measured variables. The changes in Hct, Hb, and Osm were 3.14%, 0.92g·dl-1, and 9.58 mOs/kg-1, respectively. The changes in PV, calculated from the increase in Hct alone and from changes in Hct and Hb, was found to be -10.4% and -11.2%, respectively. It is suggested that very short periods of maximal exercise can bring about some 10%-15% drop in PV. Mechanisms for this decrease are not clear. It could result from changes in tissue osmolality, filtration pressure, or opening up of collapsed capillaries.

Key words

plasma volume - maximal exercise - hematocrit - hemoglobin - osmolality

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