Throughout the life of a racehorse, there’s no question that his body will change in a multitude of ways. But what can you do today to boost the impact of strengthening and conditioning tomorrow?

A group of leading equine orthopedic researchers is trying to figure out how you can promote optimal muscoskeletal development in your young horses — giving them the best possible grounding for soundness and success in the long term.

Story by Lindsay Day
Photos by Brian Acton

Our bodies are constantly in flux. The deceivingly simple process of staying alive requires a constant balance between losing cells and creating new ones to take their place. By the time you finish reading this sentence, upwards of 200,000 cells in your body will have died and been replaced.

The variety of things our cells do also contributes to the ever-changing make-up of our body. How our cells behave is influenced, in turn, by the sorts of activities we engage in day to day. Regular weight-lifting at the gym, for example, will cause muscle cells to become more active and physically increase in size.

Dr. Allen Goodship, Director of the Institute of Orthopedics and Musculoskeletal Science at the Royal Veterinary College in London, England, has been studying the process of musculoskeletal adaptation in the horse — how bones, muscles, joints and tendons respond and adapt to the physical forces imposed on them. Like others in this field of research, he is particularly interested in the ways this process might be optimized as a horse grows and develops. What can we do with our young horses, he wants to know, to give them the best opportunity for physical success in the future?

“We know that the bones in your body respond to the amount of load you put on them and the pattern of loading they are subjected to,” explains Goodship. “So when it comes to the development of the young horse, it would seem sensible that as the skeleton is growing and developing you begin to introduce the pattern and type of loading that it is going to experience as an adult in athletic performance, so that the body develops and adapts to resist those loads in an optimal way.”

The musculoskeletal system of the horse includes the boney skeleton as well as its supporting structures – the muscles, tendons, ligaments, joints and cartilage. But when it comes to their ability to adapt in response to increasing physical demands, not all tissues of the musculoskeletal system are created equally. Unlike bone and muscle, which continue to respond to conditioning throughout life, cartilage and tendon show a limited capacity to both adapt and repair in the mature horse, a characteristic that may make them particularly vulnerable to injury with age. Encouraging the optimal development of these tissues is therefore thought to be of utmost importance.

Based on their growing understanding of musculoskeletal growth in the horse, Goodship and his colleagues believe that it may be possible to influence the development of these less adaptable tissues within the first two years of the horse’s life. “We know biologically that some of these tissues have this window of opportunity for plasticity in the early stages of development that we feel is then lost when they become adults,” says Goodship.

The theory is that through optimal management practices and a balanced exercise program at a young age, it may be possible to improve the final quality of tissues, potentially increasing their resistance to injury later in life.
“It’s a concept we are developing,” says Goodship. “Some of it has scientific support, and some of it we are still working out.”

What researchers do know is that stabling without turnout can have harmful effects in the growing horse in terms of bone density, cartilage and tendon composition, and gait development. It appears that free exercise in the form of turnout is essential to the healthy development of the musculoskeletal system in the young horse.

Where additional exercise has been introduced to young horses at pasture, there is some indication that cartilage and tendon in particular may respond in a beneficial way. One study noted an increase in cartilage cell viability when a controlled exercise program was introduced in addition to pasture turnout. In another study, ultrasounds showed an increase in the rate of growth of the superficial digital flexor tendon.

Whether or not these changes affect the horse’s future, susceptibility to injury remains an open question that Goodship and his colleagues would like to answer. “What we haven’t been able to do is follow those animals all the way through into their adult racing careers to see whether or not there are significant benefits,” says Goodship. “It’s still in the early stages,” he adds, “but it’s a philosophy we think is worth pursuing.”

While some exercise is beneficial, too much can be damaging, warns Goodship. “The important thing is that whatever you impose on a young horse, it should be introduced gradually and it should be closely monitored to make sure the horse isn’t showing any signs of early injury or disease.”

“In rehabilitation, the same sort of thing applies,” he continues. “When we inject stem cells into a tendon for example, that is only the first part of the therapy. The most important part is how you rehabilitate and condition that tendon as the new tissue is growing. The philosophy is the same across the board, in development and training right through to rehabilitation after injury. The trick is getting the right type of exercise, the right intensity and the right graded increase over time. And the people that can optimize that are often the ones whose animals or athletes under their management do best.”

Getting it right is something Goodship believes may depend as much on the individual horse as it does on anything else. “That’s why you have to monitor the individual and tailor the exercise program to their individual personality and physiology,” he says. “It’s both a science and an art.”

Pick up this issue of Trot to read the rest of this story, which covers key points about bone, tendon, and cartilage.