Exercise modifies the age-related change in crimp pattern in the core region of the equine superficial digital flexor tendon.

This research paper examines the impact of exercise on the age-related changes in the microscopic structure of the equine superficial digital flexor tendon, which is often implicated in significant horse injuries. The findings indicate that exercise routines involving galloping may alter the natural, age-related reduction in the wave-like structure of the tendon’s collagen fibrils, potentially increasing the risk of injury.

Objective of the Study

• The aim of this study was to investigate the effect of exercise on the structural changes associated with age in the equine superficial digital flexor tendon. More specifically, it focused on how exercise impacts the crimp (or wavy) pattern of the collagen fibrils that make up the tendon and provide its tensile strength.

Methodology

• The study was conducted on superficial digital flexor tendons from 18 horses that presented for necropsy, with nine horses being exercised and the other nine non-exercised, based on their recent functions.
• The crimp morphology characteristics, namely the crimp angle and crimp period length, were determined and compared between the exercised and the non-exercised groups, especially in horses below 10 years of age.

Key Findings

• The study found that five of the eight exercised horses below the age of 10 years showed significantly lower crimp angle in the central region of the tendon compared to the periphery. Three of these five animals also exhibited a significantly lower crimp period length in the centre.
• None of the non-exercised horses in this age group demonstrated such regional differences.
• The changes in the central region crimp morphology did not occur in non-exercised horses that may have previously undergone galloping activity, suggesting such changes were either absent or had returned to normal over time.

Implications of the Study

• This study implies that regular, intense exercise like galloping might alter the natural age-related reduction of the crimp angle in the tendon’s core. This occurs likely due to the increased number of rapid high-strain cycles that the collagen fibrils in exercised horses experience.
• These alterations can potentially weaken the tendon by causing cumulative subclinical microscopic damage, increasing the risk of complete or partial tendon rupture, a common injury in sport horses.

Conclusion

• The article concludes that consistent exercise regimens, particularly those involving galloping, modify the normal age-related pattern of the equine superficial digital flexor tendon. This modification may contribute to a greater risk of injury, providing important information for the management and prevention of such injuries in horses.