Continued from page 1...
Does Your Horse Have a Metabolic Disorder?
L-carnitine (LC) and acetyl-l-carnitine (ALC) are normally present in skeletal muscle. At rest, L-carnitine predominates while levels of acetyl-L-carnitine rise precipitously with exercise. LC and ALC are readily interconverted in the cell and supplementation with ALC also increases levels of LC.1 It is well known that LC is required to carry long chain fatty acids across the mitochondrial membranes so they can be burned in the mitochondria as fuel, but it is the metabolic activity of ALC that is of most interest.
The documented roles of ALC of importance in exercising muscle include:
• ALC has antioxidant activity while LC does not1
• By capturing and recycling excess acetyl groups produced in the breakdown of pyruvate from glucose, ALC supports muscle aerobic energy generation2
• The captured acetyl groups are also used to replenish phosphocreatine stores during recovery after exercise2
• ALC supports normal activation of the AMP-activated protein kinase (AMPK) enzyme system which directs glucose into energy pathways and inhibits glycogen formation3
Signs of Poor Muscular Metabolism/Adaptation
• High resting muscle tone. Muscles at rest, even when fit, should feel firm, not hard. They should have the consistency of a beef roast.
• Poorly developed musculature, loss of bulk
• Sensitivity to palpation
• Trembling or tightening triggered by palpation
• Deterioration of gait without obvious skeletal lameness; “colt sore”
• Failure to meet training milestones
• Poor attitude toward work
• Deterioration of performance
• Excessive sweating
L-leucine is the most abundant amino acid in skeletal muscle. Both L-leucine and it's metabolite beta-hydroxymethylbutyrate (HMB) are highly anabolic – stimulating muscle protein synthesis while inhibiting breakdown.4 It is a significant source of aerobic TCA intermediates during exercise5 where it's oxidation conserves glycogen and reduces lactate levels by diverting pyruvate metabolism away from conversion to lactate and redirecting it into alanine. There is also evidence that even increased dietary total protein intake may not provide sufficient L-leucine for optimal muscle function during exercise.6
Methylation is a biochemical reaction involving the transfer of a methyl group – CH3. Methylation influences all body functions via control of DNA transcription and is a key detoxification pathway. In muscle, methylation is required for the synthesis of creatine, carnitine, CoQ10 and the major antioxidant, glutathione.
Betaine (trimethylglycine - TMG) is a methylated version of the amino acid glycine which functions as a methyl group donor in methylation reactions. It is a powerful osmolyte, optimizing cellular hydration and strength generation during rehydration with both endurance and sprinting activity.7 Betaine supplementation also improves the anabolic response to exercise8 and enhances power, force and endurance. 9, 10
Beta-alanine is a unique structural conformation of the amino acid alanine. It is not incorporated into enzymes or other proteins but combines with L-histidine to form carnosine, a major intracellular buffer controlling pH of muscle cells. Beta-alanine supplementation sustains optimal energy production in muscle under conditions which call for high power output. 11, 12 It is also one of only a very few supplements that may be of benefit even to highly trained athletes. 13
Like all proteins, muscle maintenance and hypertrophy depend on adequate levels of key essential amino acids or protein tissue assembly will stop. L-lysine has long been recognized as the first limiting amino acid in common equine diets, meaning it is the one most likely to be deficient. 14
Sulfur is an important mineral for plant growth and required for the formation of the essential amino acid L-methionine in grasses. Since the institution of acid rain pollution control measures, sulfur in soils in many areas has dropped significantly, resulting in lower methionine levels in grasses, hays and grains. 15
In addition to being a structural amino acid in protein synthesis, L-methionine is required for the formation of taurine, SAM-e and glutathionine. Together with lysine, it generates L-carnitine. These are compounds of great importance to metabolism and muscle function.
The correct supplementation is a powerful legal support for normal muscle bulk, function and performance.
About Dr. Kellon
Dr. Eleanor Kellon, staff veterinary specialist for Uckele Health & Nutrition, is an established authority in the field of equine nutrition for over 30 years, and a founding member and leader of the Equine Cushings and Insulin Resistance (ECIR) group, whose mission is to improve the welfare of horses with metabolic disorders via integration of research and real-life clinical experience. Prevention of laminitis is the ultimate goal. www.ecirhorse.org
Uckele Health & Nutrition, maker of CocoSoya, is an innovation-driven health company committed to making people and their animals healthier. On the leading edge of nutritional science and technology for over 50 years, Uckele formulates and manufactures a full spectrum of quality nutritional supplements incorporating the latest nutritional advances. www.uckele.com.
1. Marzo A et al. Effect of acetyl-L-carnitine treatment on the levels of levocarnitine and its derivatives in streptozotocin-diabetic rats. Arzneimittelforschung. 1993 Mar;43(3):339-42.
2. Seller SE et al. Carnitine Acetyltransferase Mitigates Metabolic Inertia and Muscle Fatigue during Exercise. Cell Metab. 2015 Jul 7;22(1):65-76
3. Zhang Z et al. Acetyl-l-carnitine inhibits TNF-alpha-induced insulin resistance via AMPK pathway in rat skeletal muscle cells. FEBS Lett. 2009 Jan 22;583(2):470-4
4. Wilkinson DJ, et al. Effects of leucine and its metabolite β-hydroxy-β-methylbutyrate on human skeletal muscle protein metabolism. J Physiol. 2013 Jun 1;591(11):2911-23.
5. Knapik J et al. Leucine metabolism during fasting and exercise. J Appl Physiol. 1991 Jan;70(1):43-7.
6. Mero A. Leucine supplementation and intensive training. Sports Med. 1999 Jun;27(6):347-58.
7. Armstrong LE et al. Influence of betaine consumption on strenuous running and sprinting in a hot environment. J Strength Cond Res. 2008 May;22(3):851-60
8. Apicella JM et al. Betaine supplementation enhances anabolic endocrine and Akt signaling in response to acute bouts of exercise. Eur J Appl Physiol. 2013 Mar;113(3):793-802
9. Hoffman JR et al. Effect of betaine supplementation on power performance and fatigue. J Int Soc Sports Nutr. 2009; 6: 7.
10. Lee EC et al. Ergogenic effects of betaine supplementation on strength and power performance. J Int Soc Sports Nutr. 2010; 7: 27.
11. Saunders B et al. β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis. Br J Sports Med. 2017 Apr;51(8):658-669.
12. Trexler ET et al. International society of sports nutrition position stand: Beta-Alanine. J Int Soc Sports Nutr. 2015 Jul 15;12:30.
13. Zanella BP et al. Effects of beta-alanine supplementation on performance and muscle fatigue in athletes and non-athletes of different sports: a systematic review. J Sports Med Phys Fitness. 2017 Sep;57(9):1132-1141
14. Ott EA et al. Lysine Supplementation of Diets for Yearling Horses. J Ani Sci. 1981 Dec; 53(6) 1496–1503.
15. Menz FC, Seip HM. Acid rain in Europe and the United States: an update. Envir Sci & Pol. 2004 Aug; 7(4) 253-265.