Making Sense of Muscle Metabolism in Horses

The strength of any horse lies in part on its muscular well-being. Optimal nutrition and thoughtful training strategies result in muscle accretion over time, observable on physical examination. On a microscopic level, though, what happens to muscle cells as training progresses, from week to week, month to month?

Using sophisticated analytical technologies, researchers recently dove into this metabolic netherworld in an effort to characterize the metabolites found in skeletal muscle of exercised horses.^* Metabolites are the end products of cellular regulatory processes. The field of study that measures metabolites in response to environmental stimulus, like exercise, is referred to as metabolomics. It utilizes mass spectrometry or nuclear magnetic resonance spectrometry to analyze many different metabolites in a biologic sample.

In this study, the researchers collected muscle biopsies from unexercised Standardbreds and sent them to a laboratory so metabolites could be identified and quantified. The same horses then trained for 12 weeks, after which muscle biopsies were again harvested and examined for metabolites. The metabolite composition of the two sets of samples were compared.

Training significantly altered the skeletal muscle metabolome, according to the researchers. Of particular interest, exercise-induced changes to the metabolome resulted in an increase in almost every type of measured lipid molecule, as well as the branched-chain amino acids (valine, leucine, and isoleucine), tyrosine (another amino acid), and phenylalanine (a precursor for tyrosine, dopamine, and adrenaline).

What does this mean for the horse owner? While still in its infancy, metabolomic screening could ultimately be used to “track the impact of training and fitness on equine health.”

“Once a better understanding of muscle metabolism and the metabolites involved in training and recovery has been achieved, researchers will be able to tweak the nutritional needs of competitive horses to facilitate the production of energy and removal of wastes. In turn, this could possibly lead to a better understanding of training-related conditions such as recurrent exertional rhabdomyolysis,” suggested Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research.

Kentucky Equine Research helps horses recover from training and competition through multiple products, including:

• Nano-Q10, a highly bioavailable form of coenzyme Q10, also known as ubiquinone, involved in numerous reactions in the body, primarily the production of energy, and is found in highest concentrations in mitochondria; and
• Restore, a paste or powder that replenishes valuable electrolytes lost during exercise, expediting muscle recovery.

^*Klein, D.J., K.H. McKeever, E.T. Mirek, and T.G. Anthony. 2020. Metabolomic response of equine skeletal muscle to acute fatiguing exercise and training. Frontiers in Physiology 11:110.