Once available only at racetracks and high profile training facilities, equine swimming pools and underwater treadmills are becoming increasingly more popular and accessible to all horse owners. Today, private conditioning and rehabilitation facilities are easily found in highly horse populated areas and most offer haul-in day packages that allow horse owners to take advantage of the benefits of these aquatic therapies. AQUA01

Here Dr. Steve Adair, MS, DVM, Diplomate of the American College of Veterinary Surgeons and American College of Sports Medicine and Rehabilitation, gives an overview of the pros and cons of using swimming and underwater treadmills as a means of conditioning and rehabilitating the equine athlete.

Adair, an associate professor of equine surgery, currently serves as the director of equine performance medicine and rehabilitation at the University of Tennessee in Knoxville. In 2011, he presented a paper on the use of aquatic therapies, namely swimming and underwater treadmills, in conditioning and treating tendon and ligament injuries at the American Association of Equine Practitioners’ (AAEP) Convention. This December, Adair will co-lead a discussion on sports injury rehabilitation strategies at the upcoming AAEP Convention in Nashville, Tenn.

He took an interest in aquatic therapies several years ago before the University of Tennessee built their sports medicine and rehabilitation facility.

“I knew there had to be more that we could do than just standing a horse in stall or hand walking,” he said. “I knew there was more that we could do for these athletes.”


Overall benefits

Swimming and underwater treadmills primarily provide cardiovascular workouts without stressing the musculoskeletal systems, says Adair. Eliminating the weight of the rider, the concussion on the ground—“pounding” as Adair refers to it—and impact of the horse’s own weight can potentially reduce the wear and tear on a horse’s body.

“You can condition them without pounding on their joints,” he explains. “You get a really good workout without a rider on their backs and without the ground-force reactions up the hoof and through the leg. You can potentially reduce your chances of injury because you’re not ‘pounding’ on them as much. You save them a little bit.”

The lack of musculoskeletal stress also makes swimming and underwater treadmills extremely advantageous when rehabilitating injuries, adds Adair. They allow horses to maintain their cardiovascular fitness, muscle tone and improved joint movement without stressing injuries that are in the process of healing during the rehabilitation process.

“When we talk about rehabilitating injuries, we’re talking about soft tissue injuries for the most part—tendon and ligament injuries,” explains Adair. “Anything you want to exercise without full weight on it is fair game.”

Additionally, swimming and underwater treadmills force horses to use their muscles different because they are either totally non-weight bearing (swimming) or partially weight-bearing (underwater treadmill).

“They use different muscles than when they are on land,” states Adair. “That’s why you get the fantastic muscle development. You see the back and neck development and a more rounded appearance.”

Water works

The resistance of the water in both the pool and treadmill is largely responsible for the muscle development and cardiovascular workout.

“Resistance is what increases the work,” Adair explains. “It increases the amount of work to move those limbs. Say you’re in a swimming pool. It takes more muscle activation to move your arm through water than it would to move through just air. That’s due to resistance. So not only are you getting a cardiovascular workout, but you also get increased muscle action.”

In addition to the simple resistance of the water itself, both pools and underwater treadmills can increase resistance with currents.

“Bubbling air and turbulence inside water increases resistance to motion,” Adair explains. The in-ground underwater treadmill at the University of Tennessee has both jets and blowers to add resistance. “I can turn on the jets and blowers and create a pretty significant current in the treadmill itself. That increases the workload so you get a great cardiovascular workout because it takes more muscle action and contraction to move that limb through the turbulent water.”



Swimming allows a horse work in a completely non-weight bearing environment and provides one of the best cardiovascular workouts available. However, there are some drawbacks due to mechanics of how horses actually swim.

“Horses aren’t natural swimmers,” says Adair. “For the most part, all of them will propel themselves with their hind legs, and they use their front legs like rudders to steer. They really don’t ‘dog paddle.’ They become really lordotic, meaning they really arch their back. They are very violent as far as the propulsion with their rear legs.”

Due to the unnatural arching of their backs—basically their spine hollows out and compresses—and violent kicking action, swimming isn’t recommended for horses with rear limb injuries or back pain.

“If you do have a rear limb injury, especially something involving a joint like a stifle, you could potentially make it worse simply because of the violent kicking action they have in the rear.”

Hydrostatic pressure, the pressure of the weight of the water on the body, can also be a problem for a swimming horse.

“Their ventilation isn’t as natural based on the pressure of the water in the pool on their chest,” Adair explains. “You can get some ventilation perfusion mismatches. So they’re not ventilating as naturally as they would if they were on the ground or on the treadmill even. If you had a horse with any type of pulmonary issues, you could potentially make those worse.”

Despite its limitations, swimming is a great cardiovascular conditioning option for most horses.

“If you’re taking a normal, healthy individual and you’re trying to get them fit for a sale or show, it’s a heckuva of a workout,” he says. “It does give them fantastic muscle and a fantastic cardiovascular workout.”


Underwater treadmills

Unlike traditional, dry treadmills which can reach speeds of 45 to 50 mph, underwater treadmills don’t move near as fast, about 15 mph max.

Underwater treadmills come as in-ground and above ground units. With the in-ground underwater treadmill, the horse is walked onto the water-covered treadmill. In the above ground unit, the horse is walked onto a treadmill with a waterproof container and the water is added. Although in-ground underwater treadmills hold more water to increase buoyancy, water levels are more adjustable in above ground units.

Adair has both types of underwater treadmills at the Equine Performance and Rehabilitation department at the University of Tennessee.

“I think I can treat much more with an underwater treadmill with less risk than swimming,” says Adair. “It’s much more adaptable to different injuries and isn’t as limited as a pool. You can put a horse with stifle issue or back issues in (an underwater) treadmill. You can vary water height and speed and decrease the chances of worsening any type of problem.”

With an underwater treadmill, a horse is still partially weight bearing.

“In the underwater treadmill, we cannot make them totally non-weight bearing, or even approach it,” said Adair. “Some of it depends on the size of the horse. If I took a miniature or small pony and put it in my underwater treadmill, I could make them non-weight bearing, but for your average-sized horse, or even a larger Warmblood-type, I’m looking at 65 percent in weight bearing.”

The reduction in weight-bearing is due to buoyancy, the power of the water to lift a body upward.

“You can increase buoyancy by increasing salinity,” notes Adair. “Think about going to the Dead Sea, it’s hyperosmolar. It’s so salty that you can float and not sink. Same thing goes with treadmills and pools. Salt will add another five to ten percent buoyancy.”

In the underwater treadmill, horses have their workload increased due to the resistance of the water, but the buoyancy decreases the impact forces on the limbs.

“If you had a horse with a bowed tendon, you’re actually not loading that tendon to its fullest extent in the underwater treadmill because you’re not fully weight-bearing due to buoyancy,” he adds.

Buoyancy is changed by varying water levels, and that can come in handy when tailoring workouts to specific injuries.

“If you wanted to tailor the therapy to joint motion, certainly raising and lowering the water will change the amount of flexion,” Adair says. “If you take the water at hoof level, as it rises, you get more flexion in the joints. Once it reaches the hock or carpus (knee) flexion levels out, and once it reaches the elbow it flattens out.”

Due to the non-violent movement of a horse on an underwater treadmill, Adair said he will start putting injured horses in the unit when they’ve been cleared for hand walking.

“They get a better cardiovascular workout with less stress on their limbs than hand walking alone,” he says. “Really the only thing I don’t put in the treadmill is something that’s got stitches or an open wound.”


Cross Training

Neither swimming nor underwater treadmill workouts should be a horse’s sole source of conditioning. Typically, horses at rehabilitation and conditioning centers split time between aquatic conditioning and standard flat groundwork.

“Here they go on a resistance-free walker or Equineciser in the morning and then in the underwater treadmill, or vice versa,” says Adair.

Although some horse owners mistakenly assume that these aquatic therapies have the potential to decrease bony density due to reduced or eliminated ground contact, Adair says that’s just not the case.

“If you’re talking about a normal horse that’s in a pool or treadmill for 30 minutes, every single day—as long as they’re turned out or have some other form of conditioning, you’re not going to have any decreases in bone density. Where you are going to see decreases in bone density is standing a horse in a stall. That’s well accepted that they’re going to have a significant decrease in bone density within a month.”

What you do see in some cases is a decrease in proprioceptive input—the body’s ability to recognize and control the movement of their body.

“Even though you’re not totally making a horse non-weight bearing, you certainly are decreasing the proprioceptive input when you put them into the treadmill because you are decreasing weight bearing,” he says. “With any aquatic therapy—swimming or treadmill—you need to try to do some kind of ground or flat work to make sure you do maintain that proprioceptive input and recognition, so they know where their feet are.”


Picking a facility

For safety reasons, you always want to use a well-established facility, run by experienced personnel. While there are no established protocols for introducing horses to swimming pools or treadmills, both require a period of training and adjustment for the horse.

“It’s very important that the handlers be thoroughly familiar with the equipment and must be able to read the horse’s temperament,” Adair says. “The handler should be able to anticipate and correct problems with the horse before they develop.”

When choosing a facility, Adair encourages horse owners to work with facilities managed by properly certified personnel, which means either a veterinarian or license human physical therapist. However, he acknowledges those facilities aren’t always available. The main difference he says is a veterinarian’s ability to monitor lameness during the therapy.

“I can look at a horse from a medical aspect not just a conditioning aspect,” he says. “Every horse we put in the treadmill goes through a lameness exam. I know what degree of lameness they have. I can check them daily for worsening lameness. I think you get better supervision that way, but the problem is there’re not a lot of facilities that provide that. Most places, a veterinarian comes in once a week and the rest of the time they’re under the management of very knowledgeable non-veterinarians.”

Adair encourages horse owners to ask a lot of questions when picking any type of swimming or underwater treadmill facility.

“You want to see a plan,” he says. “You want to know what the process is. How do you train them? How do you decide when to take them up to the next level? Say they’re doing 15 minutes in the underwater treadmill. What makes you decide to take them up to 30 minutes a day? You want some rationale other than he’s been doing that for weeks and we decided it was time to take him up.”


Indications for Aquatic Therapy

  • Rehabilitation after injury or surgery
  • Soft tissue injuries
  • Post-arthroscopic surgery
  • Replacement for hand-walking
  • Non-displaced fractures
  • Joint stiffness, osteoarthritis
  • Increased muscle development
  • Encourages symmetric gait and back development
  • Cardiovascular conditioning
  • Reconditioning after a lay-up


Contraindications for Aquatic Therapy

  • Acute joint inflammation
  • Skin infections
  • Open wounds
  • Upper limb lameness (Underwater treadmill, OK; Made worse with swimming)
  • Back pain (Underwater treadmill, OK; Made worse with swimming)
  • Acute Myositis (muscle inflammation)
  • Cardiovascular compromise
  • Respiratory disease (possibly limiting for horse with EIPH, or “bleeders”)
  • Freshly repaired fractures

*Source: Henry S. Adair III, MS, DVM, Diplomate ACVS, ACVSMR in “Aquatic Therapy for Conditioning and Treatment of Tendon and Ligament Injuries” as presented at the 2011 American Association of Equine Practicioners Annual Convention in San Antonio, Texas.

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Tanya Randall is an avid barrel racer and regular contributor to Barrel Horse News. Email comments on this article to [email protected].


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