Researchers in Oklahoma are studying how the horse’s skeletal muscle tolerates strenuous exercise, in what will be one of the most comprehensive assessments of skeletal muscle function undertaken in any species.
In the landmark study, Dr Michael Davis and his team at Oklahoma State University’s College of Veterinary Medicine are aiming to gain a better understanding of the horse’s skeletal muscle function, and how a horse’s skeletal muscle tolerates, or doesn’t tolerate, the high temperatures and high levels of lactic acid typical of strenuous exercise.
Skeletal muscle, also called voluntary muscle, is the most common of the three types of muscle. Skeletal muscles are attached to bones by tendons, and they produce all the movements of body parts in relation to each other. Unlike smooth muscle and cardiac muscle, skeletal muscle is under voluntary control.
Davis said the findings would eventually shape what other labs do for every other species including humans.
“A basic understanding of how skeletal muscle responds to high temperatures generated during exercise and whether or not you can improve that tolerance through conditioning is going to benefit anything that’s exercising,” Davis said.
Davis is a professor at the university’s College of Veterinary Medicine, the Oxley Endowed Chair in Equine Sports Medicine and the director of the Comparative Exercise Physiology Laboratory.
“When the horse exercises, the muscle temperature goes up tremendously and the muscle starts producing a lot of lactic acid. The belief is that this contributes to the horse eventually tiring, but we don’t know that for sure. Now we have the right instrumentation to be able to determine how well the horse’s muscles tolerate those kinds of conditions.
“We also have the ability to look at the horse’s muscle over time. We can see whether or not the muscle of the horse tolerates heat and lactic acid more and is able to continue to work correctly even in the face of temperatures up to 108 or 110 degrees Fahrenheit with pH values down close to six.”
The study has taken eight horses who had been out of work for some time and were completely unfit. A muscle biopsy is used to analyze the muscle tissue under different conditions. Then, the horses undergo a 10-week conditioning programme, similar to what trainers would use at a racetrack to get the horse fit. Once the horses are fit, another biopsy is taken to see whether the horse’s skeletal muscle has changed with regards to how well it handles high temperatures and low pH.
Davis said the study will provide a better understanding of what conditioning is doing and what it isn’t doing.
“Being able to identify horses that are particularly sensitive to high temperature or low pH may mean that those horses may need a different training programme, or may simply need to do a different sport than what somebody originally had in mind for them,” he said.
The work is being funded by a Grayson-Jockey Club grant and Davis said that while the project doesn’t necessarily have an immediate application, it will allow other researchers to come up with projects that will be immediately applicable because there will be a much better understanding of how the horse works.
“This is a far-reaching project that is going to shape many different projects down the road. This has been a long process. While we have had the machines for nearly 10 years, we had to test them, test the assays and make sure everything was in line before we started spending grant money. But we’re really hitting our stride now. We are generating data that is going to mean a lot to many different people and that’s exciting.”