Title page for ETD etd-02102005-131245


Type of Document Dissertation
Author Hess, Tanja Maria
Author's Email Address thess@vt.edu
URN etd-02102005-131245
Title Potassium-free and potassium-containing electrolytes affect plasma ions and acid-base status of endurance horses
Degree PhD
Department Animal and Poultry Sciences
Advisory Committee
Advisor Name Title
Kronfeld, David S. Committee Chair
Geor, Raymond J. Committee Member
Houston, Michael E. Committee Member
Saker, Korinn E. Committee Member
Splan, Rebecca K. Committee Member
Keywords
  • calcium
  • equine
  • endurance exercise
  • neuromuscular hyperexcitability
  • potassium
Date of Defense 2005-01-10
Availability unrestricted
Abstract
Effects of potassium supplementation were evaluated in four studies in endurance horses during races and treadmill exercise. In the first and second studies a potassium-free experimental formula was compared to potassium rich commercial formulas. The first study showed that supplementation increased plasma [K+], and that the extra sodium in the potassium-free experimental formulas helped to attenuate acidosis at the end of the ride. In the second study supplementation also increased plasma [K+], however speeds were lower and no increases were observed in plasma concentrations during the race. Supplementation of potassium during recovery helped to restore plasma [K+]. Higher plasma [Ca++] was found in horses supplied with experimental feeds, due to a lower dietary cation anion balance (DCAB). Three eliminated horses had heart rate arrhythmias and labile heart rates accompanied with higher plasma [K+] and lower [Ca++] than finishers. Also horses supplied with the experimental sodium-rich formula were less dehydrated than the ones receiving commercial formulas. The third study involved an 80 km endurance exercise test on the treadmill, and plasma [K+] was affected by potassium supplementation during exercise and recovery. The supply of potassium caused higher plasma [K+] helping to restore body stores. Also chloride supply in the electrolyte formulas maintained plasma [Cl-] levels during exercise and affected plasma concentrations during recovery. The fourth study showed that potassium supply affects plasma concentration, but also increases lactate production and glucose during sub-maximal exercise. A potassium-free electrolyte supply caused higher plasma [Ca++] during exercise. Higher sodium supply in the potassium-free electrolytes improved hydration during exercise. These studies show that potassium should supplemented after exercise and but not be done during exercise because of the risk of increased neuromuscular excitability.
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