Certain exercise regimens and intensities could increase insulin sensitivity in horses, thereby reducing insulin resistance, according to the results of a recently completed study.

"Exercise has been shown to improve insulin sensitivity in horses; however, it was unclear what exercise intensity is required for this improvement," explained study author Tanja Maria Hess, MV, PhD, assistant professor in the Department of Animal Sciences at Colorado State University’s College of Agricultural Sciences.

"A better understanding of the effect of different exercise regimens on insulin sensitivity is needed to develop effective management strategies and exercise recommendations by which owners may reduce insulin resistance-related health risks," she relayed.

To that end, Hess and colleagues employed 31 healthy horses of mixed breeds residing at the Second Calvary and Guard Regiment of the Brazilian Army, in Rio de Janeiro. "The majority of the horses in this study were young and not obese, thus lowering the risk of insulin resistance," the team noted.

Prior to the start of the study, which was carried out in 2007, two qualified individuals evaluated each horse’s body condition score, and researchers tested each horse’s fasting blood-glucose and insulin levels and calculated proxies for insulin sensitivity.

During the study the horses resided in individual box stalls unless they were turned out or being exercised. Each horse consumed 6 kg of a commercially available concentrate (split into three 2 kg feedings) and 4 kg of Bermudagrass hay (split into two 2 kg feedings) daily.

The team placed all horses on a strict physical activity schedule detailed in the table below:

November 2006-January 2007 Turnout 8 hours 4 days/week Turnout
February Walk
60 minutes
6 hours
3 days/week
3 days/week
March Walk and Trot
90 minutes
8 hours
3 days/week
2 days/week
April-June Turnout 8 hours 4 days/week Turnout
July-October Walk and Trot 90 minutes 5 days/week Moderate
November 2007-January 2008 Turnout 8 hours 4 days/week Turnout

Upon reviewing the study results, researchers determined the horses’ base insulin concentrations were highest during the months of turned out only and lowest during the months they received moderate exercise. Likewise, the team found insulin sensitivity was highest during months the horses were exercised moderately and lowest during months the horses were only turned out. In both scenarios, levels were in the middle when the horses received light exercised..

"Moderate exercise intensity performed five days a week seems to benefit insulin sensitivity," Hess concluded. "Turnout may not be sufficient to improve insulin sensitivity, but an exercise regimen comparable with light or moderate intensity exercise, as performed in the study, may be recommended as a management strategy to improve insulin sensitivity."

She relayed that the next step is to evaluate a population of obese horses at risk for insulin resistance in a similar study.

The study, "Comparison of Insulin Sensitivity of Horses Adapted to Different Exercise Intensities," appeared in the November 2011 issue of the Journal of Equine Veterinary Science. The abstract can be viewed online.