Swimming Can Improve Horse Glucose, Insulin Levels
When insulin’s up, surf’s up? While you might not send your horse surfing, researchers have learned that swimming can help regulate his insulin levels.

Both blood glucose and blood insulin values improved in Thoroughbreds training on a daily swimming routine, making this low-intensity exercise program a good way to help manage insulin regulation, said Paolo Baragli, DVM, PhD, and Micaela Sgorbini, DVM, PhD, researchers in the University of Pisa Department of Veterinary Sciences, in Italy.

“With swimming, we can maintain adequate levels of glucose uptake (and even improve it) without having negative outcomes related to the hoof impact on the ground,” he said.

In their study, Baragli, Sgorbini, and their fellow researchers worked 12 Thoroughbred geldings gradually up to a daily swimming session of 60 minutes in an equine pool. They compared insulin and glucose levels before and after a full month of the routine. To do so, they tested plasma insulin and glucose concentrations at multiple intervals (5, 15, 25, 35, 45, and 60 minutes) after an intravenous injection of glucose, at the start and the end of the training month. They also monitored the horses’ heart rates and blood lactate levels during exercise.

They found significantly higher blood glucose levels before the training period than afterward—an indication that the swimming helped the horses’ cells take up the glucose, they said. Meanwhile, blood insulin levels at 45 and 60 minutes post-glucose injection were much higher before the training period compared to after. That means the horses managed their insulin response to glucose better after a month of swimming sessions.

While traditional training on the ground might have similar effects on glucose and insulin values, swimming offers additional options, the researchers said.

“Swimming pool training is very useful for horses that have recovered from surgical treatment of orthopedic problems that need to train aerobically without forcing their skeletal apparatus once it has recovered,” Sgorbini added. “In this perspective, I suggest training horses in swimming pools under the supervision of veterinarians or trainers with an expertise in this field.”

Baragli added, “Only a veterinarian can decide if and when a horse can replace ground exercise with swimming. If a horse is lame, you first must have a proper diagnosis because there some kinds of lameness are contraindicated for swimming (such as most muscle, ligament, and tendon pathologies).”

Based on their study results, the team believes swimming could have particular benefits for horses with insulin dysregulation issues. “When insulin is dysregulated, such as with equine metabolic syndrome, affected horses don’t need training per se, but simply exercise (as is the case with human obesity) to lose weight and to reduce insulin resistance,” Sgorbini said.

But even healthy horses can benefit from a swimming program, he continued. “I’m primarily a researcher in horse behavior and welfare,” Baragli said. “So I see a welfare perspective here, as well. I believe that, when possible, swimming could be a greater opportunity to vary the monotony of certain training programs without losing stamina, thus allowing us to train not only the body but even the mind. That’s a very interesting application, I believe.”

Swimming pools are ideal because they provide for better control of timing and circumstances, he said. But even natural bodies of water make good swimming areas for horses, provided they’re safe (from strong currents and underwater obstacles, for example). “Also keep in mind that, like with humans, salt water can sustain the body better than fresh water can,” Baragli said.

The study, “How swimming affects plasma insulin and glucose concentration in Thoroughbreds: A pilot study,” was published in the Veterinary Journal.