Skip to main content

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

  • Amanda Waller (a1), George J Heigenhauser (a1) and Michael I Lindinger (a1)

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.

Corresponding author
*Corresponding author:
Hide All
1Lindinger, MI, McKeen, G and Ecker, GL (2004). Time course and magnitude of changes in total body water, extracellular fluid volume and plasma volume during submaximal exercise and recovery in horses. Equine and Comparative Exercise Physiology 1: 131139.
2Waller, A and Lindinger, MI (2005a). Time course and magnitude of fluid and electrolyte shifts during recovery from high intensity exercise in Standardbred racehorses. Equine and Comparative Exercise Physiology 2: 7787.
3Ecker, GL and Lindinger, MI (1995). Water and ion losses during the cross-country phase of eventing. Equine Veterinary Journal Supplement 20: 111119.
4Hyyppa, S, Saastamoinen, M and Poso, AR (1996). Resortation of water and electrolyte balance in horses after repeated exercise in hot and humid conditions. Equine Veterinary Journal Supplement 22: 108112.
5Waller, A and Lindinger, MI (2005b). Physicochemical analysis of acid–base status during recovery from high intensity exercise in Standardbred racehorses. Equine and Comparative Exercise Physiology 2: 119127.
6Schott, HC, Dusterdieck, KF, Eberhart, SW, Woody, KA, Refsal, KR and Coenen, M (1999). Effects of electrolyte and glycerol supplementation on recovery from endurance exercise. Equine Veterinary Journal Supplement 30: 384393.
7McCutcheon, LJ, Geor, RJ, Hare, MJ, Ecker, GL and Lindinger, MI (1995). Sweating rate and sweat composition during exercise and recovery in ambient heat and humidity. Equine Veterinary Journal Supplement 20: 153157.
8Schott, HC and Hinchcliff, KW (1993). Fluids, electrolytes and bicarbonate. In: Hinchcliff, KW and Sams, RA (eds) Veterinary Clinics of North America: Equine Practice – Drug Use in Performance Horses. Philadelphia, PA: WB Saunders, pp. 577604.
9Marlin, DJ, Scott, CM, Mills, PC, Louwes, H and Vaarten, J (1998). Rehydration following exercise: effects of administration of water versus an isotonic oral rehydration solution (ORS). Veterinary Journal 156: 4149.
10Stewart, PA (1983). Modern quantitative acid–base chemistry. Canadian Journal of Physiology and Pharmacolgy 61: 14411461.
11Lindinger, MI and Waller, A (2007). Muscle and blood acid–base physiology during exercise and in response to training. In: Hinchcliff, KW, Geor, RJ and Kaneps, AJ (eds) Equine Exercise Physiology. New York: Elsevier Press, pp. 350381.
12Szucsik, A, Baliskonis, V and McKeever, KH (2006). Effect of seven common supplements on plasma electrolyte and total carbon dioxide concentration and strong ion difference in Standardbred horses subjected to a simulated race test Equine and Comparative Exercise Physiology 3: 3744.
13Marlin, DJ, Scott, CM, Schroter, RC, White, S, Nyrop, KA, Maykuth, PL and Harris, PA (1996). Physiological responses in nonheat acclimated horses performing treadmill exercise in cool (20°C/40%RH), hot dry (30°C/40%RH) and hot humid (30°C/80%RH) conditions. Equine Veterinary Journal. Supplement 22: 7084.
14Marlin, DJ, Scott, CM, Schroter, RC, Mills, PC, Harris, RC, Harris, PA, Orme, CE, Roberts, CA, Marr, CM, Dyson, SJ and Barrelet, F (1999). Physiological responses of horses to a treadmill simulated speed and endurance test in high heat and humidity before and after humid heat acclimation. Equine Veterinary Journal 31: 3142.
15Poso, RA and Hyyppa, S (1999). Metabolic and hormonal changes after exercise in relation to muscle glycogen concentrations. Equine Veterinary Journal Supplement 30: 332336.
16Constable, PD (1997). A simplified strong ion model for acid–base equilibria: application to horse plasma. Journal of Applied Physiology 83: 297311.
17Lindinger, MI, Heigenhauser, GJF, McKelvie, RS and Jones, NL (1992). Blood ion regulation during repeated maximal exercise and recovery in humans. American Journal of Physics 262: R126R136.
18Brownlow, MA and Hutchins, DR (1982). The concept of osmolality: its use in the evaluation of “dehydration” in the horse. Equine Veterinary Journal 14: 106110.
19Waller, A, Smithurst, KJ, Ecker, GL, Geor, RJ and Lindinger, MI (2005). Cyclical plasma electrolyte and acid–base responses to meal feeding in horses over a 24-h period. Equine and Comparative Exercise Physiology 2: 159169.
20Lindinger, MI, Heigenhauser, GJF and McKelvie, RS (1995). K+ and Lac−  distribution in humans during and after high-intensity exercise: role in muscle fatigue attenuation? Journal of Applied Physiology 78: 765777.
21Lindinger, MI and Ecker, GL (1995). Ion and water losses from body fluids during a 163 km endurance ride. Equine Veterinary Journal Supplement 18: 314322.
22McCutcheon, LJ and Geor, RJ (1998). Sweating. Fluid and ion losses and replacement. In: Hinchcliff, KW (ed.) Veterinary Clinics of North America: Equine Practice; Fluids, Electrolytes and Thermoregulation in Horses. Philadelphia: WB Saunders, pp. 7579.
23Parks, CM and Manohar, M (1984). Blood–gas tensions and acid–base status in ponies during treadmill exercise. American Journal of Veterinary Research 45: 1519.
24Stutz, WA, Topliff, DR, Freeman, DW, Tucker, WB, Breazile, JW and Wall, DL (1992). Effect of dietary cation–anion balance on blood parameters in exercising horses. Equine Veterinary Science 12: 164167.
25Sosa Leon, LA, Hodgson, DR, Carlson, GP and Rose, RJ (1998). Effects of concentrated electrolytes administered via a paste on fluid, electrolyte, and acid–base balance in horses. American Journal of Veterinary Research 59: 898903.
26Maughan, RJ and Lindinger, MI (1995). Preparing for and competing in the heat: the human prespective. Equine Veterinary Journal Supplement 20: 815.
27Gisolfi, CV, Summers, RW, Schedl, HP and Bleiler, TL (1992). Intestinal water absorption from select carbohydrate solutions in humans. Journal of Applied Physiology 73: 21422150.
28Dyer, J, Fernandez-Castano Merediz, E, Salmon, KS, Proudman, CJ, Edwards, GB and Shirazy-Beechey, SP (2002). Molecular characterization of carbohydrate digestion and absorption in equine small intestine. Equine Veterinary Journal 34: 349358.
29Friend, TH (2000). Dehydration, stress, and water consumption of horses during long-distance commercial transport. Journal of Animal Science 78: 25682580.
30McConaghy, FF, Hodgson, DR, Evans, DL and Rose, RJ (1995). Equine sweat composition: effects of adrenaline infusion, exercise and training. Equine Veterinary Journal. Supplement 20: 158164.
31Kerr, MG and Snow, DH (1983). Composition of sweat of the horse during prolonged epinephrine (adrenaline) infusion, heat exposure, and exercise. American Journal of Veterinary Research 44: 15711577.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Equine and Comparative Exercise Physiology
  • ISSN: 1478-0615
  • EISSN: 1479-070X
  • URL: /core/journals/equine-and-comparative-exercise-physiology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed