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Electrolyte supplementation after prolonged moderate-intensity exercise results in decreased plasma [TCO2] in Standardbreds

Published online by Cambridge University Press:  01 November 2007

Amanda Waller*
Affiliation:
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ont., CanadaN1G 2W1
George J Heigenhauser
Affiliation:
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ont., CanadaN1G 2W1
Michael I Lindinger
Affiliation:
Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ont., CanadaN1G 2W1
*
*Corresponding author: awaller@uoguelph.ca
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Abstract

The present study used the physicochemical approach to characterize the changes in acid–base status that occur in Standardbreds after post-exercise electrolyte supplementation. Jugular venous blood was sampled from six conditioned Standardbreds on two separate occasions, at rest and for 24 h following a competitive exercise test (CET) designed to simulate the speed and endurance test of a 3-day event. After the CETs, horses were given water ad libitum and either a hypotonic commercial electrolyte solution, via nasogastric tube followed by a typical hay/grain meal, or a hay/grain meal alone. The electrolyte supplementation resulted in c. 2 mmol l− 1 decreased plasma [TCO2] during the recovery period as compared with control. The primary contributor to the decreased [TCO2] with electrolyte supplementation was a decreased strong ion difference ([SID]), as a result of the non-significant increase in plasma [Cl− ]. Additionally, electrolyte supplementation resulted in faster restoration of hydration status compared with control, as evidenced by faster recovery of plasma [protein] and total weak acid concentration ([Atot]). It is concluded that oral administration of a hypotonic electrolyte solution after prolonged moderate-intensity exercise diminishes the post-exercise alkalosis, and that recovery of hydration status is still incomplete 24 h after exercise when no electrolytes are given. Thus, supplementation with electrolytes according to estimated sweat losses may attenuate post-exercise increases in plasma [TCO2], which is of significant practical interest to the horse racing community, as a testing threshold of greater than 37 mmol l− 1 is used by many racing jurisdictions to determine whether a horse has been administered an alkalinizing agent.

Type
Research Papers
Copyright
Copyright © Cambridge University Press 2008

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