The effect of previous conditioning exercise on diaphyseal and metaphyseal bone to imposition and withdrawal of training in young Thoroughbred horses.

The research paper studies how prior conditioning exercise impacts the response of specific horse bones to training and its withdrawal in young Thoroughbred horses. It found that the horses which had undergone regular exercise from a young age had stronger and larger bones than those which only had spontaneous exercise, and this difference remained even after adjusting for training workload.

Research Methodology

• The study involved 19 Thoroughbred horses aged 2 to 3 years, divided into two groups – those that only had spontaneous exercise at pasture (PASTEX group), and those who had both spontaneous exercise at pasture and additional imposed exercise from a very young age (CONDEX group).
• Researchers studied the diaphysis of the proximal phalangeal bone and the third metacarpal bone (Mc3), as well as the Mc3 proximal metaphysis.
• They employed quantitative computed tomography scans to analyze aspects like bone mineral content, size, density, periosteal and endosteal circumference, cortical thickness, and an estimation of bone strength.

Findings

• At the beginning of the observation period, the horses in the CONDEX group exhibited larger and stronger bones than those in the PASTEX group.
• The differences between the two groups persisted even when adjustments were made for training workload.
• The increase in bone strength was due to an increase in size, not density.
• While bone density increased during training, it dropped during paddock rest. However, bone strength continued to rise due to slow growth.
• The most significant variance in response to training (with respect to diaphyseal bone mineral content, bone strength index, or cortical thickness) was linked to the cumulative workload index at the gallop.

Conclusions

• No differences were observed in bone response to training except for the endosteal circumference at 55% of the Mc3 length from the carpometacarpal joint space between the CONDEX and PASTEX groups. This suggests that young horses may be exercised slightly more aggressively than what is currently believed.

This study enlightens a better understanding of the bone response to training and rest in Thoroughbred horses, and that previous conditioning exercise could potentially lead to greater bone strength and resilience.