Early Exercise and Future Tendon Health

Japanese researchers report in a recent study that applying structured exercise regimens early in horses' lives can potentially alter the development of their tendons to benefit future athletic ability and limit tendon injury later in life. These results were based on the fact that exercise regimens didn't appear to have deleterious effects on tendocytes, or tendon cells.

According to Alicia L. Bertone, DVM, PhD, Dipl. ACVS, from the Comparative Orthopedic Research Laboratory at The Ohio State University, "Tendon injuries are an important cause of wastage in athletic horses, particularly (when injuries occur in) energy storing tendons--such as the superficial digital flexor tendon (SDFT)--which act like springs to contribute to movement."

To determine if a structured exercise program imposed early in a horse's life could improve the quality of developing tendons to limit exercise-related injuries later, a group of researchers from the Japan Racing Association Equine Research Institute divided 14 foals into exercise and control groups.

All foals were turned out on pasture for four hours per day, but horses in the exercise group received an additional period of treadmill exercise five times per week. When the horses reached 15 months of age, the researchers evaluated the microscopic structure, biochemical composition, and biomechanical properties of the SDFTs and the common digital extensor tendons (CDET--a positional tendon).

Overall, no important differences in tendon characteristics between the SDFT and the CDET or between the exercise and control groups were identified.

"It is possible that no difference in tendon development occurred because the exercise program was still within the normal physiologic range, which minimized any adaptive changes in the tendon," suggested Bertone.

Alternatively, changes in cellular metabolism or gene expression--factors that were not measured in this study--might have occurred, potentially resulting in altered tendon matrix production or tenocyte efficiency to repair tendon micro-damage.

Because the imposed, structured exercise program did not result in any notable deleterious changes to the SDFT, the researchers recommended the introduction of athletic training to young horses to limit tendon injuries later in life.

According to Bertone, "Further research in this field is clearly indicated considering the importance of tendon injuries in horses."

The study, "Can exercise modulate the maturation of functionally different immature tendons in the horse?" was published in the Journal of Applied Physiology in December 2007.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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