Researchers Evaluate Overtraining's Effects on Horses

Researchers Evaluate Overtraining's Effects on Horses

Researchers working toward developing a test to identify overtraining learned the practice can have negative effects on the horse.


Are you overtraining your horse? You might soon be able to answer this question with a simple home test. A team of Dutch researchers is currently trying to find the specific biomarkers that would make such a test possible.

The team's most recent research, which focused on pinpointing biomarkers in muscle tissue, not only revealed signs of horses overworking but also showed how devastating overtraining can be, said Marinus te Pas, PhD, senior researcher of genomics and bioinformatics in the Animal Breeding and Genomics Centre at Wageningen UR Livestock Research, in Lelystad.

“The present study was a first step that showed that overtraining adversely affected both muscle tissue (function) and health-threatening functions like stress—including apoptosis (programmed death) of cells—and immune functions,” said te Pas. “We now know the genes responsible, and we can use this information to develop a simple test (based on urine, blood, or saliva samples).”

Te Pas and his fellow researchers—Inge Wijnberg, DVM, PhD, and Han van der Kolk, DVM, PhD, both of Utrecht University in The Netherlands—followed two groups of young Standardbred geldings in training over an 18-week period. One group of horses followed a “regular” training protocol, while the other group followed an “intense” training protocol followed by a four-week period of “detraining” (a very low-intensity protocol). In common practice, “detraining” is intended to “undo” the harmful effects of intense training, te Pas said.

The researchers performed muscle biopsies on each horse several times during the research period to analyze molecular changes caused by the training regimen. However, contrary to what they had expected, the biopsies revealed changes not only to muscle-specific processes but also to body-wide processes, said te Pas.

Regular training most affected muscle-specific protein metabolism and increased carbon dioxide export from tissues, he said. With intense training, energy metabolism rose, and fatty tissues and the heart were affected.

The researchers found that overtraining’s effects were significantly harmful to the horse’s heart, musculoskeletal system, and immune system, he added. They also found that despite its good intentions, “detraining” did not reduce the adverse effects of certain aspects of overtraining. In fact, te Pas said, based on his findings, he said he would not recommend instituting detraining protocols to compensate for overtraining.

While the study did reveal important biomarkers in overtraining, those biomarkers are currently only detectable in muscle tissue, requiring a muscle biopsy—a complicated procedure, he said.

“Since no one would like to use biomarkers using muscle tissue, we need to translate the results to be detected in (blood) plasma, saliva, or urine,” said te Pas. “This would be the next research step that would allow us to develop the biomarker that can be used by trainers.”

Depending on funding sources, a practical overtraining biomarker test could be ready within three years, te Pas said.

The study, "Skeletal muscle transcriptome profiles related to different training intensities and detraining in Standardbred horses: A search for overtraining biomarkers," will appear in an upcoming issue of the Veterinary Journal

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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