A new mathematical model suggests that reducing high-speed training distances and allowing longer recovery periods could help Thoroughbred racehorses maintain stronger, healthier bones.
Getting a racehorse fit enough to compete involves a careful balance. Training helps bones adapt to the demands of racing, but repeated loading can also cause microscopic damage that leaves them vulnerable to injury.
Researchers at the University of Melbourne have developed a mathematical model to explore that balance, examining how different combinations of training and rest affect bone adaptation, damage and repair.
Their findings suggest that lower training volumes, while retaining some high-speed work, could support bone development while reducing the accumulation of damage.
When training outpaces repair
Bone is living tissue that continually responds to the forces placed upon it. As a horse trains, its bones adapt to cope with repeated loading by changing their structure and density.
However, those same forces can also produce tiny cracks, known as microdamage.
The body repairs this damage by removing damaged bone and replacing it with new tissue. Problems arise when damage accumulates faster than the repair process can keep up, potentially increasing the risk of fracture.
Rest and less intensive exercise therefore play an important role in giving bone time to recover.
Modelling what happens inside the bone
The new research brings together models of bone adaptation, damage accumulation and repair to simulate how Thoroughbred bone responds to different training schedules over time.
The team calibrated the model using bone data from postmortem studies of racehorses that had been in training or resting.
They focused on bone within the fetlock joint, an area exposed to substantial forces during fast exercise and a common site of serious racing injuries.
Using a typical training routine reported by trainers in Victoria, Australia, as a starting point, the researchers adjusted gallop distances and the frequency and duration of rest periods.
This allowed them to explore the potential effects of different programmes without exposing live horses to experimental workloads.
High-speed distance matters
The model predicted that both speed and the total distance covered at high speed influenced the accumulation of bone damage.
Longer distances at faster speeds produced more damage, highlighting why the amount of fast work matters alongside overall fitness.
However, removing demanding exercise altogether is not the answer. Bones need an appropriate training stimulus to develop the strength required for racing.
The findings instead suggest that reducing training volume while retaining some high-speed exercise could help achieve the necessary adaptation with less accumulated damage.
Giving bones time to recover
Recovery periods also made a substantial difference.
In the simulations, two or more rest periods lasting at least six weeks each year reduced predicted bone damage by allowing more time for repair. Longer and more frequent breaks generally produced greater reductions.
The researchers also found that periods of low-intensity training could provide an alternative to some rest periods, provided horses still had at least one substantial rest each year.
These findings offer a potential direction for training management, rather than a fixed timetable suitable for every horse.
Towards more informed training decisions
The research provides a way to investigate processes that are difficult to monitor directly inside a living horse’s bones.
However, the results are predictions from a mathematical model. They do not establish that a particular schedule will prevent injuries in individual horses, or demonstrate how changes would affect race performance.
The researchers hope the approach could eventually help trainers and veterinarians develop more individual training and rehabilitation programmes, balancing the exercise needed to prepare horses for racing with sufficient time for bone repair.
Protecting bone health could also benefit horses beyond the racecourse, helping them move into second careers and enjoy a comfortable retirement.
To read the research paper: How much training is too much for a racehorse? New bone research has some answers”, published 13 October 2026, click here.
