My horse Esprit on the Aquatred at the University of Tennessee Veterinary Medical Center.

Event horses log hundreds of hours of conditioning work over the course of their careers. We set our watches and go pounding around the field, cranking out a carefully programmed agenda of trot and gallop sets. But the high level of fitness that is required for eventing also comes at the cost of extra wear and tear on our horses’ limbs.

Some years ago, I was campaigning an aging upper-level eventer who, after a decade in the sport, had developed some garden variety arthritis. My vet, Dr. Steve Adair of the University of Tennessee Veterinary Medical Center, had an compelling idea: Why not do some of his fitness work in the hospital’s underwater treadmill? “There is a certain amount of weight reduction so you’re not having the concussive forces on the limbs,” Dr. Adair explains. “You get a longevity of the joint because you don’t have to work them as hard on dry land. Also, working in the water you can really get an exaggerated flexion so if you have stiff joints it helps with joint mobility.”

UT’s first treadmill, an above-ground AquaPacer … 

… which was replaced in spring 2013 by an in-ground Aquatred.

We put him on a twice-a-week winter program and the results were astonishing. Not only did he breeze effortlessly around his spring events, he literally looked and felt like a different horse. My lanky, catlike OTTB now had a bulked-up topline and strong, powerful glutes — it was like he had started lifting weights. But what really surprised me was the difference it made in our dressage. He felt freer through his shoulder and better able to “sit” in collected work.

“I think that the underwater treadmill targets a different set of muscles than what you get with your flatwork,” Dr. Adair explains. “It has been shown to improve the core muscles, and when you improve the core muscles you improve the overall stability of the horse. When you have core stability and muscle fitness and cardiovascular fitness, you’re going to have a better athlete overall.”

The concept of using water resistance for conditioning is nothing new. Swimming racehorses is a common practice, either in specially designed pools or in open water.

Racehorses swimming off Reen Pier in West Cork, Ireland:

According to Dr. Adair, swimming is great cardiovascular exercise but can be problematic, as horses aren’t natural swimmers. They use their back end for propulsion via a violent kicking-out motion that can exacerbate stifle issues, and they travel inverted, which encourages an upside-down muscle development that is undesirable for sport horses. They also lose their proprioceptive input, which is based on their ability to feel the ground, so if you were to condition horses exclusively in the swimming pool, they could become clumsier under saddle.

The underwater treadmill has long been a staple of injury rehabilitation therapy, but in recent years it has edged its way into the sport horse community for a different purpose. Veteran four-star eventer Beth Perkins of Rutherfordton, N.C., is one top rider who has embraced the technology not just for fitness but for improved general performance. This is the third year in a row she has incorporated the HydroHorse Treadmill at nearby Still Creek Farm into Sal Dali’s preparations for Rolex.

Beth Perkins and Sal Dali at Rolex 2013. Photo by Jenni Autry.

Owned by Cynthia Barclay, the 16-year-old OTTB is a big-boned, rangy horse with high withers and a tendency toward a hollow topline. The underwater treadmill, Perkins says, has refashioned his musculature in a way that has made a tangible difference under saddle. She notes that straightness has been a recurring struggle for Sal due to an old racing injury. While there’s no way to force a horse to work equally off both sides while riding — they can always find a way to compensate for weaknesses — it’s impossible to cheat in the water. “It has helped him learn to use himself more evenly,” Perkins says.

Increased strength and mobility through the shoulder is another benefit. Not only has the treadmill helped Sal develop a more expressive trot, Perkins believes it has improved his jumping ability as well. “It strengthens the connective tissue they need to get their front end up and out of the way,” she says.

Sal’s pre-Rolex treadmill program began at the end of last year with several sessions of half-hour walks. Trot sets were gradually incorporated, with jets turned on to decrease drag, and at the season’s peak, he’ll be doing three sets of 7- or 8-minute trots. The 3-day-a-week program supplements a traditional conditioning schedule, and oftentimes he’ll do the treadmill as a warmup for jumping or in addition to a regular gallop with an abridged long trot set beforehand.

Of course, your horse doesn’t have to be on the road to Rolex to benefit from a underwater treadmill conditioning program. Look for a facility in your area that has one, as they’re becoming increasingly commonplace in rehab centers, high-performance barns and vet clinics. It may take a few sessions to acclimate, but most horses, once they understand what is being asked of them, take the new exercise in stride. My horse Esprit strides happily into water with ears pricked and seems to genuinely enjoy the work.

Beth recommends building up your horse’s underwater treadmill program gradually. I’ve had great experiences working with the technicians at both Still Creek and UT to develop a custom conditioning schedule for my horses — they’re very much interested in under-saddle feedback and working to address specific problems and goals. For Esprit, a typical workout includes 45 minutes in the water once a week, with 9-, 7- and 5-minute trot sets spread out over a distance of about 3-and-a-half miles. Even with a significantly reduced dry-land conditioning program due to the inclement weather we’ve experienced this winter, Esprit skipped around his first prelim event of the season and recovered virtually immediately.

Esprit conditioning last winter at the Aqua Rehab Center at Still Creek Farm (Columbus, N.C.).

One underwater treadmill critique I’ve heard circulated is that it can soften a horse’s hooves, although that hasn’t been my experience. Some horses certainly have more high-maintenance feet than others, but Dr. Adair insists that with proper care and dressing, the treadmill shouldn’t do them any harm: “The amount of moisture absorbed during a 30-minute session in the Aquatred is minuscule compared to what they get standing in the dew in the morning. We have rehab horses here going in the treadmill five days a week, and they don’t have any problems.”

Another myth is that the deep water might spook event horses and make them less reluctant to jump into water complexes because of unsureness about depth. In my opinion, that theory doesn’t hold any water either, so to speak; if anything, I think it makes them more comfortable with water’s drag and splash.

Have you used an underwater treadmill for fitness and conditioning? Share your experience in the comments section below.

Go Eventing!