Exercise of young thoroughbred horses increases impact strength of the third metacarpal bone.

This research study explored how varying exercise routines among young thoroughbred horses influenced the mechanical properties of their bone material, finding that intensive exercise led to a substantial increase in the horses’ bone impact strength.

Research Objectives

• The researchers aimed to investigate the effect of exercise on the bone material properties of young thoroughbred horses.
• This research was motivated by a lack of knowledge on how exercise impacts bone’s material properties.
• The hypothesis for the study was that substantial differences in training regimens would lead to noticeable changes in the horses’ bone mechanical properties.

Methodology

• The study involved eight thoroughbred racehorses, split between two different exercise regimens for 19 weeks when they were approximately 19 months old.
• The control group consisted of four horses that were only walked for 40 minutes daily.
• The exercise group (also four horses) had additional 20-minute trotting sessions daily, plus progressively intensive treadmill workouts.
• Longitudinal beam specimens of the mid-diaphysis of the metacarpal were subjected to mechanical testing until they failed or broke.

Findings

• No significant difference was observed for Young’s modulus (a measure of material stiffness) or bending strength between the two groups.
• The position within the bone cortex from which the specimens were sourced seemed to influence these properties somewhat.
• The specimens from the exercised horses showed slightly higher toughness, indicated by the area under the load-deformation curve (work).
• Impact strength (resistance to force or shock leading to deformation) in the bones of the exercised horses was substantially higher than in the control group horses.
• Bones from both groups showed higher impact strength in their outer cortex compared to their inner cortex.
• Impact strength seemed positively correlated with the amount of microcracking produced during testing, implying that the bone responded to increased loading by enhancing its ability to microcrack and, therefore, improve its toughness.

Implications and Conclusions

• This research adds to the understanding of how exercise influences the material properties of bone, specifically in the context of young racehorses.
• The findings suggest that intensive exercise can help enhance bone impact strength and toughness in maturing horses.
• This knowledge could guide the development of training programs for young thoroughbred racehorses to maximize their skeletal health and improve their performance.