Genetic Response to Training Found

Researchers measured the way muscle genes are switched on and off when a Thoroughbred exercises and found that these genes work together to adapt to exercise training.

"As any trainer knows, different muscles respond and adapt to training in different ways," said Beatrice A. McGivney, PhD, of the University of Dublin in Ireland. "A person who is a long distance runner and another person who is a weight lifter do a lot of exercise, but their muscles respond differently and look differently. We have previously identified the genes that are required for normal functioning muscle in horses. Following this, we looked at what genes are switched on or off following training."

While every cell in a horse contains the same genes inherited from the sire and the dam, only the genes required in a specific tissue are expressed (turned on) in that particular tissue. For example, there are genes specifically associated with eye function that are expressed in the eye. Similarly, there are genes that are only switched on in muscle tissue.

"In addition, specific genes are also turned on and off under different physiological conditions--for example, during exercise," McGivney said.

She and her colleagues set out to identify genes that play an important role in exercise and muscle performance in Thoroughbreds. They aim to take what they learn to develop genetic tests that breeders and trainers can use; knowing which genes switch on during training provides an important framework for future studies on disease and performance, McGivney said. Eventually, re

searchers, veterinarians, and trainers could use this information to develop better training programs, and they might consider itwhen pairing sires and dams to breed athletes. "This belief is supported by the fact that myostatin, a gene which was switched off following exercise, is related to best race distance in Thoroughbreds. The Myostatin protein acts as a 'brake' on muscle growth and exercise causes a reduction in the production of myostatin, thereby releasing this 'brake' and facilitating muscle growth," she said.

"While this study only looked at Thoroughbred horses, which all undertook the same exercise regime, it is predicted that different types of exercise would result in different changes," she added. "Different types of exercise result in different physiological changes in the horse's muscle and abilities and these differences are likely to be reflected in the genetic changes."

The study, "Characterization of the equine skeletal muscle transcriptome identifies novel functional responses to exercise training," was published in July online ahead of print in BMC Genomics.

The abstract is available on PubMed.

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