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Does usefulness of potassium supplementation depend on speed?
Equine Vet J Suppl. 2006 AugEV

Abstract

REASONS FOR PERFORMING STUDY

Electrolyte mixtures given to counter sweat loss usually contain abundant potassium. However, increases in plasma [K+] occur with exercise and supplementation may further increase plasma levels, potentially increasing the risk of neuromuscular hyperexcitability and development of adverse clinical sequellae. This proposition requires study.

OBJECTIVES

To compare effects of a K-rich electrolyte supplement (EM+K) to a K-free one (EM-K) on plasma [K+], [Ca++] and acid-base status during an endurance incremental exercise test on the treadmill.

METHODS

The test consisted of 3 bouts (simulating loops in an endurance race) of 12 km performed at 6, then 7, then 8 m/sec with 25 min rest stops (S1, S2) between loops on 13 endurance trained Arabian horses (7 EM-K, 6 EM+K). Electrolytes were supplied orally 60 mins before exercise (Pre) and at each stop. Blood samples were taken before exercise and during exercise, each S and 120 mins of recovery (R). Blood was analysed for pH, PCO2, packed cell volume (PCV), plasma [Na+], [K+], [Cl-], [Ca++], glucose, and lactate [La-]; plasma [H+] and osmolality (osm) were calculated. The dietary cation anion difference (DCAD) was calculated to be -27 meq/dose EM-K and 109 meq in EM+K, respectively.

RESULTS

Plasma [H+] decreased during the 6 and 7 m/sec loops, increased during the 8 m/sec loop, and returned to Pre at S1, S2 and R. Plasma [K+] was higher at 8 m/sec and plasma [Ca++] was overall lower in the EM+K group compared to EM-K. Other findings included higher overall PCV, overall glucose, and [La-] during the 8 m/sec loop (P<0.040) in EM+K compared to EM-K horses.

CONCLUSIONS

EM+K supplementation leads to higher plasma [K+] increasing the risk of neuromuscular hyperexcitability during exercise. Acute effects of a lower DCAD in EM-K may have led to higher plasma [Ca++]. Potassium-rich electrolytes may have triggered the release of epinephrine, contributing to higher PCV, glucose release and increased lactate production.

POTENTIAL RELEVANCE

Lower plasma [K+] and higher plasma [Ca++] with EM-K supplementation may help reduce the risk of conditions associated with neuromuscular hyperexcitability occurring especially during higher speeds in endurance races.

Authors+Show Affiliations

Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0306, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17402396

Citation

Hess, T M., et al. "Does Usefulness of Potassium Supplementation Depend On Speed?" Equine Veterinary Journal. Supplement, 2006, pp. 74-9.
Hess TM, Kronfeld DS, Carter RA, et al. Does usefulness of potassium supplementation depend on speed? Equine Vet J Suppl. 2006.
Hess, T. M., Kronfeld, D. S., Carter, R. A., Treiber, K. H., Byrd, B. M., Staniar, W. B., Smith, L. T., Gay, L. A., & Harris, P. A. (2006). Does usefulness of potassium supplementation depend on speed? Equine Veterinary Journal. Supplement, (36), 74-9.
Hess TM, et al. Does Usefulness of Potassium Supplementation Depend On Speed. Equine Vet J Suppl. 2006;(36)74-9. PubMed PMID: 17402396.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Does usefulness of potassium supplementation depend on speed? AU - Hess,T M, AU - Kronfeld,D S, AU - Carter,R A, AU - Treiber,K H, AU - Byrd,B M, AU - Staniar,W B, AU - Smith,L T, AU - Gay,L A, AU - Harris,P A, PY - 2007/4/4/pubmed PY - 2007/5/3/medline PY - 2007/4/4/entrez SP - 74 EP - 9 JF - Equine veterinary journal. Supplement JO - Equine Vet J Suppl IS - 36 N2 - REASONS FOR PERFORMING STUDY: Electrolyte mixtures given to counter sweat loss usually contain abundant potassium. However, increases in plasma [K+] occur with exercise and supplementation may further increase plasma levels, potentially increasing the risk of neuromuscular hyperexcitability and development of adverse clinical sequellae. This proposition requires study. OBJECTIVES: To compare effects of a K-rich electrolyte supplement (EM+K) to a K-free one (EM-K) on plasma [K+], [Ca++] and acid-base status during an endurance incremental exercise test on the treadmill. METHODS: The test consisted of 3 bouts (simulating loops in an endurance race) of 12 km performed at 6, then 7, then 8 m/sec with 25 min rest stops (S1, S2) between loops on 13 endurance trained Arabian horses (7 EM-K, 6 EM+K). Electrolytes were supplied orally 60 mins before exercise (Pre) and at each stop. Blood samples were taken before exercise and during exercise, each S and 120 mins of recovery (R). Blood was analysed for pH, PCO2, packed cell volume (PCV), plasma [Na+], [K+], [Cl-], [Ca++], glucose, and lactate [La-]; plasma [H+] and osmolality (osm) were calculated. The dietary cation anion difference (DCAD) was calculated to be -27 meq/dose EM-K and 109 meq in EM+K, respectively. RESULTS: Plasma [H+] decreased during the 6 and 7 m/sec loops, increased during the 8 m/sec loop, and returned to Pre at S1, S2 and R. Plasma [K+] was higher at 8 m/sec and plasma [Ca++] was overall lower in the EM+K group compared to EM-K. Other findings included higher overall PCV, overall glucose, and [La-] during the 8 m/sec loop (P<0.040) in EM+K compared to EM-K horses. CONCLUSIONS: EM+K supplementation leads to higher plasma [K+] increasing the risk of neuromuscular hyperexcitability during exercise. Acute effects of a lower DCAD in EM-K may have led to higher plasma [Ca++]. Potassium-rich electrolytes may have triggered the release of epinephrine, contributing to higher PCV, glucose release and increased lactate production. POTENTIAL RELEVANCE: Lower plasma [K+] and higher plasma [Ca++] with EM-K supplementation may help reduce the risk of conditions associated with neuromuscular hyperexcitability occurring especially during higher speeds in endurance races. UR - https://www.unboundmedicine.com/medline/citation/17402396/Does_usefulness_of_potassium_supplementation_depend_on_speed L2 - https://doi.org/10.1111/j.2042-3306.2006.tb05517.x DB - PRIME DP - Unbound Medicine ER -