BRANCH CHAIN AMINO ACIDS & TYING-UP…

Posted by Ranvet NZ , 10 Apr, 2009

Vitamins/Supplements

Nutrient Engineering Affects Performance!

Post-exertional rhabdomyolysis otherwise known as ‘tying-up' imposes not only significant welfare implications to horses afflicted but also significant loss of days training and substantial monetary loss indicated for treatment.

There are a number of theories in regards to causative agents. The condition is likely multi-factorial meaning there is more than one singular contributing factor to a horse suffering an episode. One factor all theories have in common is that the syndrome results from metabolic abnormalities within muscle cells that are triggered by physical exertion. In particular, several of these theories suggest that uncompensated over production of free radicals may result in oxidative damage of structural cellular components. Clinical symptoms presenting themselves by the way of pain, loss of neuromuscular responsiveness, tissue damage and leakage of intracellular enzymes into the extracellular fluid. Due to this leakage, a tentative diagnosis may be confirmed by an elevation in serum AST activity in blood samples drawn 24 hours after the onset of functional deficit/clinical signs.
One potential cause of excessive production of free radicals is an inability of oxidative metabolism to limit the acidification of muscle cells during work, which results from a local deficiency of branch chain amino acids (BCAA's) at the sites of muscle oxidation. This suggests that supplemental BCAA's provided to muscle cells during work could postpone the onset of or alleviate the severity of post-exertional myopathy in equine athletes susceptible to this condition.

The five branch chain amino acids – leucine, isoleucine, valine, glutamine and carnitine are classed as ‘essential' amino acids and are most plentiful in muscle tissue – making up over one third of the volume of muscle protein. Insufficient provision may result in muscle cell damage including reduced ability of muscles to contract and relax during extreme exertion, muscle fatigue, lactic acidosis and delayed recovery as muscle tissue completes the repair process. Research has demonstrated that plasma concentrations of leucine, isoleucine and carnitine decrease during exercise, suggesting that the utilization of these amino acids is accelerated during strenuous work.
Research also supports that the effect of administration prior to hard work may be more to spare muscle tissue from breakdown during strenuous activity, therefore being a more favourable and efficacious supplementation
schedule for horses prone to episodic ‘tying-up'.

The following beneficial effects have been reported following pre-exercise supplementation of
key amino acids (BCAA's);

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